ANESTHESIA FOR LUNG RESECTION
Pre-operative considerations
Lung resections are usually carried out for the diagnosis and treatment of pulmonary tumours and less commonly for complications of infection and bronchiectasis.
Tumours
Pulmonary tumours may be either benign or malignant or can have an intermediate nature hematomas account for 90% of benign pulmonary tumours. They are usually peripheral pulmonary lesions and represent disorganized normal pulmonary tissue.
Bronchial edema are usually but occasionally locally invasive.
Malignant pulmonary tumors are divided into small cell and non small cell carcinomas
• squamous cell
• Adenocarcinoma
• Large cell
Small cell carcinoma usually presents as central masses with endobronchial lesions. Adenocarcinoma and large cell carcinoma are more typically peripheral lesions that often involve the pleural.
Clinical manifestation
Symproms may include cough, hemoptesis, dyspnea, wheezing, weight loss, fever or productive sputum.
Pleuritic chest pain or pleural effusion suggests pleural extension.
Involvement of mediastinal structure is suggested by
• hoarseness that result from compression of recurrent laryngeal nerve.
• Horner’s synd caused by involvement of the symp chain
• An elevated hemidiaphragm due to compression of phrenic nerve
• Dysphagia from compression of the esophagus
• Or supra vena cava synd.
Distant metastasis most commonly involve the brain, liver, bone and adrenal glands. Lung carcinoma can produce paraneoplastic syndrome due to ectopic hormone production and immunologic cross reactively between the tumor and normal tissues such as cushing’s syndrome, Lambert Eatsn syndrome.
Treatment
Surgery is the treatment of choice for the curative treatment of lung cancer
Resectability and operability.
Resectability is determined by the anatomic stage of the tumor, anatomic staging include: chest radiography, CT, bronchoscopy, mediastinoscopy.
Types of surgery:
Labectomy via a post thoracotomy through the fifith or sixth intercostals space is the procedure of choice for nmost lesions.
Segmental or wedge resections may be performed in patient with small peripheral lesions and poor pulmonary reserve.
Pneumonectomy is necessary for curative treatment for lesions involving the left or right main bronchus.
Operability is dependent on the extent of the procedure and physiologic status of the patient.
Pulmonary function test offer useful preliminary guidelines.
Preoperative laboratory criteria for pneumonectomy
ABG paCO2 ˃ 45 high risk patient
paO2 ˂ 50
FEV1 ˂ 2L
Predicted postop FEV1 ˂ 300ml or 40% of predicted
FEV1/FVC ˂ 50% of predicted
Maximum breathing capacity ˂ 50% of predicted
Maximum Vo2 ˂ 10ml/kg/m
The most commonly used criteria for operability is a predicted postop FEV1 greater than 800ml
Postop FEV1 = % blood flow to remaining lung X total FEV1
Anesthetic Consideration
1. Preoperative management
The majority of patient undergoing pulmonary resection have underlying lung disease. Preoperative assessment of such patient include careful history and examination, lung function tests, arterial blood gases, radiological studies. It should be emphasized that smoking is a risk factor for both COPD and CAD. Evaluation of cardiac function may include CHO, dobutamine stress echo.
Ppremedication
Patient with moderate to severe respiratory compromise should receive little or no sedative premedication.
Anticholinergics are very useful in reducing copious secretions and improve visualization during laryngoscopy and facilitate the use of fiberoptic bronchoscope.
2. Intraoperative management
Venous access
At least one large bore IV line (14-16g) is mandatory for all thoracic surgeries.
Central venous access, a blood warmer and rapid infusion device are desirable if extensive blood loss is anticipated.
Monitoring
Direct art pr monitoring is indicated for one lung anesthesia, resection of large tumours, patient with limited pulmonary reserve or cardiac dysfunction.
Pulmonary artery is indicated in patient with pulmonary hypertension or cor pulmonale.
Induction of anesthesia
After adequate pre-oxygenation, an IV anesthetic is used for induction in most patient. The selection of an induction agent should be based on the patient’s preoperative status.
Direct laryngoscopy should be performed only after deep anesthesia to prevent bronchospasm and to blunt the cardiovascular pressor response.
Endotracheal intubation is facilitated with succinylcholine or non-depolarizing agent.
Most thoracotomies can be performed with an ordinary ETT but one lung anesthesia may require the insertion of double lumen ETT.
Positioning
Most lung resections are performed with the patient in lateral decubitus position.
Maintenance of anesthesia
All anesthetic techniques have been successfully used for thoracic surgeries, but the combination of potent halogenated agent with an opioid is prefereed.
Advantages of halogenated agents
1. Dose dependent bronchodilatation
2. Depression of airway reflexes
3. The ability to use high FiO2
4. Rapid adjustment in anesthetic depth
5. Minimal effect on HPV
Advantage of opioids
1. Minimal hemodynamic effect
2. Depression of airway reflexes
3. Residual postop analgesia
Maintenance of muscle paralysis with muscle relaxant facilitate reb spreading as well as anesthesia management.
Fluid management only consists of basic maintenance requirements and replacement of blood loss with blood or colloid.
Excessive fluid administration in the lateral decubitus position may promote lower lung yndrome (gravity dependent transudation of fluid into the dependent lung) which increase intrapulmonary shunting and promotes hypoxemia specially during one lung ventilation.
Management of one lung ventilation
The greatest risk of one lung ventilation is hypoxemia. To reduce this risk the period of one lung ventilation should be kept to minimum, 100% O2 should be used.
Adjustment of vent parameters of peak airway pr rise progressively ˃ 30cmH2O tidal volume may be reduced to 6 – 10ml/kg and vent rate increased to maintain minute ventilation.
Hypoxemia during one lung anesthesia require one or more of the following intervention
Consistently effective measures
1. Periodic inflation of the collapsed lung with O2
2. Early ligation or clamping of the ipsilateral pulmonary artery
3. 5 – 10 cmH20 of CPAP to the collapsed lung
Marginally effective measures
1. Continuous insufflations of O2 into the collapsed lung
2. Changing the tidal volume and respiratory rate
3. 5 – 10 cmH2O of PEEP to the ventilated lung
Causes of persistent hypoxemia
Surgical manipulation or traction can displace endobronchial tube or the bronchial blocker causing obstruction, excessive secretion of blood clots in the airway or pneumothorax on the dependent ventilated side.
Alternative to one lung ventilation
1. Apneic oxygenation
Vent can be stopped for short period if 100% O2 is insufflated at a rate greater than O2 consumption.
Progressive respiratory acidosis limits the use of this technique to 10-20 min in most patient
2. High frequency positive pressure ventilation and high frequency set vent
A standard entrocheal tube may be used with either techniques allowing ventilation of both lungs.
Mediastinal bounce (to and pro movement) may interfere with surgery.
3. Postoperative management
General Care
Most patient are extubated early to decrease the risk of pulmonary barotraumas and infection patient with marginal pulmonary reserve should be left intubated until standard extubation criteria are met. Double lumen tube should be replaced with regular single lumen ETT.
Routine postope care should include maintenance of semiupright position, supplemental O2, incentive spirometry, close ECG and hemodynamic monitoring, postop radiograph and aggressive pain relief.
Postop analgesia
Techniques for postop pain relief may include
1. Parental opioids through patient controlled analgesia device
2. Intercostals blocks with long acting agent such as 0-5% ropivacaine may be done intraoperative under direct vision or postoperative via standard techniques
3. Thoracic lumbar epidural analgesia by opioids with or without local anesthetics can provide excellent analgesia
4. Intrapleural analgesia
Postoperative complications
Minor postop complications
1. Blood clots and thick secretion obstruction of the airways and result in atelectasis
Therapeutic bronchoscopy should be considered for persistent atelectasis
2. Air leaks from the operative hemithorax most air leaks stop after few days.
3. Bronchopleural fistular presents as sudden large leak from the chest tube that may be associated with an increasing pneumothorax and partial lung collapse.
More serious postop complication
1. Postop bleeding
Signs of hemorrhage include increased chest tube drainage ˃ 200ml/h, hypotension tachycardia and falling hematocrit.
2. Tortion of lobe or segment can occur as the remaining lung on the operative side expand tpo occupy the hemithorax.
3. Acute herniation of the heart into the operative hemithorax can occur through a pericardial defect.
Herniation into the right hemothorax results in sudden severe hypotension with elevated CVP.
Herniation into the left hemithorax results in sudden compression of the heart a AV groove resulting in hypotension, ischemia and infarction.
4. Injury to the phrenic nerve, vagus, left recurrent laryngeal.
5. Paraplegia can rarely follow thoracotomy due to spinal cord ischemia due to injury to left lower intercostals arteries.
Sunday, October 31, 2010
Friday, October 29, 2010
Anesthetic considerations for Pediatric Chest Trauma
Anesthetic considerations for Pediatric Chest Trauma
ANESTHETIC CONSIDERATIONS FOR PEDIATRIC CHEST TRAUMA
Hala samir El Mohamady, MD
Dept. of Anesthesiology, Intensive Dare, and Pain management, Faculty of Medicine, Ain Shams University
Abstract
Thoracic trauma is a major cause of morbidity and mortality in children.
The anesthesiologist needs to be prepared to manage such pediatric patient who may have severe multisystem injuries
with underlying respiratory derangements, ongoing blood loss, and cardiac dysfunction.
Many principles used in adult patients can be applied in pediatric patients; however the unique anatomy and physiology
of children must always be remembered.
For pediatric patients timely resuscitation and optimal care to avoid secondary injury is a considerable challenge for any
anesthesiologists.
Prevention of childhood injury remains the cornerstone of reducing the number of children who present for posttraumatic
surgical intervention. Beyond prevention, the next best step is the accurate diagnosis and treatment of
traumatic injury. Anesthesiologists contribute to this step by providing timely resuscitation and optimal care to avoid
secondary injury.
Introduction
Blunt and penetrating chest trauma is a major cause of
morbidity and mortality in children. Most pediatric
cases are caused by blunt trauma while penetrating
trauma is more common in adolescent boys.
Fortunately, children have an extremely compliant
body that may absorb considerable force and energy
with minimal external signs of injury. Conversely,
external signs of injury or rib fractures are an indicator
of significant potential soft tissue damage (1, 2). Young
children are less mineralized and more pliable, and
they tend to bend, but not break. Significant
intrathoracic injuries often occur without rib fractures;
however, the risk of mortality increases with the
number of ribs fractured (3) .Also Mortality from chest
trauma increases with the presence of abdominal (20%)
or head injury (35%) (4).
Evaluation and Management
Airway
Just as in the adult, the initial assessment should
concentrate on the A, B, C's (airway, breathing, and
circulation). It is important to remember the differences
in the pediatric airway, which include a large occiput,
large tongue, anterior larynx;
floppy, stiff Q-shaped epiglottis, and short trachea.
Unlike the adult, the cricoid is the narrowest part of
airway and so intubated patients should have a leak
around the endotracheal tube (ETT). The large tongue
and floppy epiglottis can contribute to airway
obstruction in an unconscious child. Appropriate jaw
thrust can lift the tongue off the back of the pharynx
and minimize airway compromise. A shoulder roll may
be required to place the head in an optimal position for
intubation; however, the presence of possible cervical
spine injury may preclude its use (5).
Any child that presents with respiratory compromise
should immediately receive supplemental oxygen with
continuous oxygen saturation monitoring. A changing
or altered mental status may indicate a closed head
injury, or severe hypovolemia.
Intubation should be considered in any child who is
combative, unconscious, or obtunded, to maintain
cerebral oxygenation and perfusion and to help
decrease the risk of secondary brain injury.
Infants and neonates are obligate nose breathers, so
occluded nasal passages from maxillofacial, neck, or
head trauma may prevent them from breathing
effectively.
Oral intubation is preferable to nasal intubation
because it is easier, faster, and less likely to result in
bleeding. Up to 50% of all pediatric trauma patients
will have brain trauma, including possible basilar skull
fracture. The cervical spine must always be protected
and the neck collar should remain in place until the
physician is absolutely sure there is no neck injury. Inline
stabilization (not traction) should be applied while
the patient is being intubated to prevent further spinal
cord injury (6). All pediatric trauma patients should be
considered at risk for aspiration particularly one with
thoracic injuries, rapid sequence induction with cricoid
pressure should be used until the airway is secured.
Cricoid pressure may destabilize an unstable neck in a
small child or infant and should be applied carefully by
experienced personnel. The ideal ETT should have a
leak at pressure <20-25 cm H20 if patient has normal
lungs. In patients with severe pulmonary trauma, a
larger ETT or cuffed ETT will facilitate ventilation. In
these patients, a leak at pressure 25-30 cm H20 will
maximize ventilation without increasing the risk of
developing subglottic stenosis (5).
Breathing
The trachea can be easily compressed; nasal flaring,
use of accessory muscles, and a "rocking boat" pattern
Ain Shams Journal of Anesthesiology Vol 2; Jan 2009
41
may indicate tracheal obstruction. The obstruction may
need to be relieved by intubation. Very rarely,
percutaneous cricothyrotomy or tracheotomy may be
required. Infants and small children are much more
dependent on diaphragmatic movement for respiration.
Anything that decreases the efficacy of diaphragmatic
motion will interfere with adequate breathing in these
patients (e.g. abdominal trauma and incorrectly
performed bag and mask ventilation. A nasogastric
tube should be expeditiously placed to deflate the
stomach.
The mediastinum in young children is very mobile and,
in the presence of a pneumothorax or hemothorax, can
easily allow compression of the heart and great vessels,
leading to a tension pneumothorax. Treatment for
pneumothorax is decompression with either a needle
placed at the mid-clavicular line of the second
intercostal space or placement of a chest tube (7).
Circulation
A change in blood pressure (BP) occurs only after there
is a 30% to 40% decrease in estimated blood volume
(EBV); therefore, BP is not a very good measure of
circulatory status. On the other hand, hypotension
indicates significant blood loss.
A systolic blood pressure of 90 mmHg or less in a child
is considered a predictive indicator of major trauma (8).
Early signs of hypovolemia include persistent
tachycardia, delayed capillary refill, and diminished
pulse pressure. Central pulses should be strong. An
absent or decreased radial pulse indicates
approximately a 10% reduction in intravascular
volume. Weakened axillary or femoral pulses signify a
loss of about 15%. It is important to calculate estimated
blood volume as soon as possible (Table 1).
Balanced salt solution (lactated Ringers or normal
saline 20 mL/kg) is most commonly used for volume
resuscitation. If there is minimal or no response to this
bolus, then an additional 2 boluses can be given while
preparations are being made to transfuse blood. The
initial dose of blood is 10 mL/kg of packed red blood
cells.
Table 1: Estimated Blood Volume in Children (2)
neonate -90 mL/kg
infant - 80 mL/kg
child -70 mL/kg
Estimated wt = (age x 2) +10
Intravenous access can often be difficult to establish in
a small child. It may be necessary to cut down on the
saphenous vein or place an intraosseous line. Femoral
lines are usually the easiest and least risky central lines
to place in these situations. The presence of a cervical
collar or possible neck injury may prevent access to the
internal jugular or subclavian vein (8).
Central Nervous System
The presence of head trauma in a patient with chest
trauma is a significant predictor of mortality. The
Glasgow Coma Scale (GCS) is not reliable in children
under 1 year of age because spontaneous motor
movements after CHI are common, which can
artificially elevate the, GCS also children may not be
able to cooperate and follow commands because of
their age or level of anxiety (9).
Specific Injuries
Pulmonary Contusion
pulmonary contusion (or lung contusion) is the most
frequent injury caused by chest trauma. It is usually
caused by blunt trauma but also explosions or a shock
wave associated with penetrating trauma can cause
lung contusion (10, 11).
Pathophysiology
Pulmonary contusion results in bleeding and fluid
leakage into lung tissue, which can become stiffened
and lose its normal elasticity. The water content of the
lung increases over the first 72 hours after injury,
potentially leading to frank pulmonary edema in more
serious cases. As a result of these and other
pathological processes, pulmonary contusion
progresses over time and can cause hypoxia. The larger
the area of the injury, the more severe respiratory
compromise will be (12).
Ventilation/perfusion mismatch
Normally, the ratio of ventilation to perfusion is about
one-to-one; the volume of air entering the alveoli
(ventilation) is about equal to that of blood in the
capillaries around them (perfusion). This ratio is
reduced in pulmonary contusion; fluid-filled alveoli
cannot fill with air, oxygen does not fully saturate the
hemoglobin, and the blood leaves the lung without
being fully oxygenated. Insufficient inflation of the
lungs, which can result from inadequate mechanical
ventilation or an associated injury such as flail chest,
can also contribute to the ventilation/perfusion
mismatch. So the mismatch between ventilation and
perfusion grows, blood oxygen saturation is reduced
(13). Pulmonary hypoxic vasoconstriction, in which
blood vessels near the hypoxic alveoli constrict in
response to the lowered oxygen levels, can occur in
pulmonary contusion. The vascular resistance increases
in the contused part of the lung, leading to a decrease
in the amount of blood that flows into it (14), directing
blood to better-ventilated areas. Although reducing
blood flow to the unventilated alveoli is a way to
compensate for the fact that blood passing unventilated
alveoli is not oxygenated, the oxygenation of the blood
remains lower than normal. If it is severe enough, the
hypoxemia resulting from fluid in the alveoli cannot be
Anesthetic considerations for Pediatric Chest Trauma El Mohamady HS
42
corrected just by giving supplemental oxygen; this
problem is the cause of a large portion of the fatalities
that result from trauma (13) .
Management
No treatment is known to speed the healing of a
pulmonary contusion; the main care is supportive (14)
Attempts are made to discover injuries accompanying
the contusion to prevent additional injury, and to
provide supportive care while waiting for the contusion
to heal (19). Monitoring, including keeping track of fluid
balance, respiratory function, and oxygen saturation
using pulse oximetry is also required as the patient's
condition may progressively worsen. Monitoring for
complications such as pneumonia and acute respiratory
distress syndrome is of critical importance (15).
Treatment aims to prevent respiratory failure and to
ensure adequate blood oxygenation (16) . The child with
mild pulmonary contusions may not need more than
good pain control, supplemental oxygen, observation,
pulmonary toilet, and early mobilization (17). More
severe injuries will be progressively more difficult to
treat. The presence of intrapulmonary shunts and
decreased compliance may necessitate mechanical
ventilation and positive end-expiratory pressure
(PEEP) (17). Overhydration can exacerbate edema and
worsen oxygenation; hypovolemia can produce
hypoperfusion and increase the risk of multiorgan
failure. So maintenance of euvolemia is important.
Inotropic agents may be required in patients with
severe pulmonary contusion. The administration of
steroids in these patients can increase the risk of
pneumonia(18).When the contusion does not respond to
other treatments, extracorporeal membranous
oxygenation may be used, pumping blood from the
body into a machine that oxygenates it and removes
carbon dioxide prior to pumping it back in(19).
Rib Fractures
Rib fractures are present in approximately one third of
children who present with thoracic trauma. The
presence of rib fracture should alert the physician to the
possibility of other significant thoracic and
extrathoracic injuries. The severity of other injuries
increased with the number of ribs fractured, as did the
mortality. All children with at least 4 fractured ribs had
other injuries. Treatment consists of maximizing
oxygenation and ventilation as necessary, treatment of
associated injuries, and ensuring good analgesia.
Intravenous opioids, patient-controlled analgesia, or
epidural analgesia can all be effective. The technique
selected will depend on the patient's underlying
condition and age (20).
Airway Obstruction
Maxillofacial trauma or laryngotracheal injury can lead
to airway obstruction. Patients may present with
hoarseness, stridor, subcutaneous emphysema, or
intercostals or sternal retractions. Injuries to the great
vessels in the neck can result in an expanding
hematoma that may compromise the airway.
Management includes jaw thrust, clearing of debris
from the oropharynx, intubation as necessary and
rarely, a cricothyrotomy or tracheostomy (21, 17) .
Pneumothorax
Pneumothorax is the most common immediately or
potentially life-threatening thoracic injury in a child.
Children higher rate of oxygen consumption and
smaller functional residual capacity makes them more
susceptible to hypoxia. The highly mobile and
compliant mediastinum in children allows the
mediastinal contents to shift to the contralateral side,
which can compromise blood return and cardiac output
so decompression of the tension pneumothorax is life
saving.
Definitive treatment is with a chest tube. The
pneumothorax may be stable until positive pressure
ventilation is instituted. Any patient who becomes
hypoxic and/or hypotensive after institution of positive
pressure ventilation, should be considered to have a
tension pneumothorax until proven otherwise.
Persistent air leak after the placement of appropriate
chest tubes may indicate a tracheobronchial tree injury.
One-lung ventilation is often necessary and can be
tricky in a small, unstable patient when operative repair
is needed (7).
Hemothorax
Pulmonary hematoma or massive hemorrhage is rare
unless accompanied by laceration to a vessel as their
lung has high levels of tissue thromboplastin and low
circulatory pressure, thereby limiting bleeding from
parenchymal injuries.
Unexplained hypotension, or chest tube output that is
initially greater than 15 mL/kg or continued bleeding
of 2-3 mL/kg/hr consider hemothorax and chest
exploration may be needed(22).
Traumatic Aortic Rupture
Injury to the great vessels has been shown to increase
mortality to more than 50%. Diagnosis of aortic rupture
is made by history and aortography. Tracheal deviation
to the right, and unequal blood pressures in the arms
may be signs of aortic rupture. On chest radiograph, a
widened mediastinum, abnormal contour of the aortic
knob, nasogastric tube deviation to the right,
depression of the left main bronchus, left hemothorax
may indicate aortic rupture necessitating urgent
exploration (23).
Flail Chest
Immediate treatment consists of applying pressure to
the flail segment to reduce chest wall instability and
minimize circulatory and ventilatory impairment. Most
Ain Shams Journal of Anesthesiology Vol 2; Jan 2009
43
children will require internal stabilization with
endotracheal intubation and mechanical ventilation.
Fluid restriction after initial resuscitation and insurance
of adequate gas exchange will minimize complications
(24) .
Myocardial Contusion and Other Cardiac Injuries
Cardiac trauma in children is relatively uncommon.
The severity of injury can vary from cardiac
concussion, which has no histologic manifestations and
is transient, to myocardial muscle or valve rupture.
These children will usually be unstable and mortality is
high (24, 25). The most common ECG abnormalities
included persistent sinus tachycardia, ST-T wave
abnormalities, conduction abnormalities, and
premature ventricular contractions (26).
Cardiac Tamponade
Cardiac tamponade is much more common with
penetrating injuries. The classic finding of Beck's triad
(muffled heart tones, increased central venous pressure,
decreased blood pressure) may be difficult to
appreciate in the small, hypovolemic child. Most
penetrating cardiac injuries will present with
hemopericardium and tamponade. Treatment is with
pericardiocentesis (7).
Anesthetic Management
Approximately 20% will require operative intervention
because of abdominal injuries, which may be
associated with massive blood loss (27).
A patient that is not already intubated, should undergo
a rapid sequence induction with cricoid pressure.
Children can desaturate much more quickly than
adults, so a modified rapid sequence induction is often
preferable. Cricoid pressure will need to be applied
carefully in the child with an unstable neck. Most of
these patients will be volume depleted and resuscitation
will be ongoing.
Induction agents that do not decrease blood pressure or
heart rate should be chosen. Ketamine or etomidate are
good choices, although small doses of thiopental or
propofol can be used in more stable patients,
particularly if they have an associated head injury (28) .
Standard monitors should be applied. Pulse oximetry
may be difficult to obtain in a small, cold
vasoconstricted patient; therefore, it is prudent to use
multiple probes in several locations. Respiratory
variation in the waveform of the pulse oximeter may
indicate hypovolemia. Bradycardia usually indicates
hypoxia, ischemia, acidosis, or hypothermia and should
be rapidly corrected. Persistent tachycardia can signify
hypovolemia and acute blood loss. End tidal carbon
dioxide (ETCO2) is less accurate in smaller patients
because they have a relatively higher dead space to
tidal volume ratio than adults. Hypovolemic patients
will have even more dead space, and patients with
thoracic injuries may have increased shunting as well.
A low ETC02 may reflect low cardiac output, because
there is less blood flow to lungs (29).
At least 2 intravenous (IV) catheters should be placed,
preferably one above and one below the diaphragm,
and blood obtained for crossmatch.
If there is difficulty obtaining peripheral IV access, a
central venous or intraosseous catheter can be placed.
Femoral venous catheters are often the easiest to get
access to, have easy landmarks and the lowest
complication rate. A subclavian catheter should always
be placed on the side of the suspected injury, especially
if there is already a chest tube on that side. Maintaining
body temperature with radiant warming lights, warm
fluids, or a forced air warmer is critical. Hypothermia
and vasoconstriction can increase coagulopathy and
bleeding, adversely affecting perfusion. Small children
have a large body surface area to mass, and
temperature control can be exceptionally difficult.
Actively warm patients if they arrive cold. The only
exception is in patients with severe closed head injury,
in whom mild hypothermia is preferred. Rewarming
may lead to increased acidosis (rewarming shock).
Invasive blood pressure monitoring will be important
and can be challenging to place. It may be necessary to
cut down on the radial artery, or to place the catheter in
the femoral, axillary, dorsalis pedis, or post tibial
arteries.
The presence of significant hypovolemia can cause
hypoperfusion and metabolic acidosis. Once
resuscitation has started, perfusion may occur to
previously underperfused areas, causing washout of
acid, vasodilatation, decreased cardiac output, and
continuing hypotension. Metabolic acidosis usually
improves with fluid resuscitation. However, in patients
with severe trauma, the acidosis may need to be treated
with sodium bicarbonate, as long as ventilation is
adequate. The Dose of bicarbonate is wt (kg) x 0.15 x
base deficit. However, since many of these patients
will have a base deficit of more than 10 mEq/L, 2 x
weight is a good starting dose.
The fluids most often used in resuscitation in children
are balanced salt solution (lactated Ringers or
Plasmalyte) or albumin.
Blood should be available and the child should be
transfused for the same indications as in adults.
Consider administration of fresh frozen plasma (FFP)
and platelets after the equivalent of 1 to 2 estimated
blood volumes have been transfused. FFP has the
highest citrate content per unit. Citrate binds with
calcium, so severe hypocalcemia may develop (citrate
intoxication) especially if FFP is administered rapidly.
Citrate toxicity is treated with calcium chloride (CaCl2)
10 mg/kg or calcium gluconate 30 mg/kg.
Hyperkalemia can occur as a result of massive blood
transfusion. One-week-old blood contains 5 mEq/L
potassium; while three-week-old blood, has 22 mEq/L
potassium. In a small child, this amount of potassium
may be significant. Treatment is with CaCl2 10 mg/kg,
Anesthetic considerations for Pediatric Chest Trauma El Mohamady HS
44
hyperventilation, and bicarbonate. If hyperkalemia
persists then glucose (0.5 gm/kg) and insulin (1
unit/5gms glucose) can be administered (7).
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pulmonary contusion". Seminars in Thoracic and
Cardiovascular Surgery 20 (1): 39–45.
15- Sutyak JP, Wohltmann CD, Larson J (2007): "Pulmonary
contusions and critical care management in thoracic trauma".
Thoracic Surgical Clinics 17 (1): 11–23.
16- Moloney JT, Fowler SJ, Chang W (2008). "Anesthetic
management of thoracic trauma". Current Opinion in
Anaesthesiology 21 (1): 41–46.
17-Ruddy RM (2005). "Trauma and the paediatric lung". Paediatric
Respiratory Reviews 6 (1): 61–67.
18- Petersen MD, Henderson B (1996): Thoracoabdominal Trauma,
in JK Hall, JM Berman (eds): Pediatric Trauma Anesthesia and
Critical Care. Armonk, NY, Futura Publishing Co, Inc, pp 245-
273.
19-. Cooper A (1995). Thoracic injuries. Semin Pediatr Surg 4:109-
116.
20- Pettiford BL, Luketich JD, Landreneau RJ (2007). "The
management of flail chest". Thoracic Surgery Clinics 17 (1):
25–33.
21-. Reilly JP, Brandt ML, Mattox KL (1998): Thoracic trauma in
children.J Trauma 34:329-331.
22- Scherer LR: Thoracic Trauma, in Oldham KT, Colobani
PM,Fogalis RP (eds) (1997): Surgery of Infants and Children:
Scientific Principles and Practice. Lippincott-Raven,
Philadelphia, PA, pp 455-461.
23- Cooper A (1995). Thoracic injuries. Semin Pediatr Surg 4:109-
116.
24- Cox CS, Black TB, Duke JH, et al (1998): Operative treatment of
truncal vascular injuries in children and adolescents. J Ped Surg
33:462-467.
25- Stafford PW, Harmon CM (1993): Thoracic trauma in children.
Current opinion. Pediatrics 5:325-332.
26- Baum VC (2002): Cardiac trauma in children. Paed Anesth 12:
110-117.
27- Hirsch R, Landt Y, Porter S (1997): Cardiac troponin 1 in
pediatrics:Normal values and potential use in the assessmentof
cardiac injury. J Pediatrics 130:872-877.
28- Gross M, Lynch F, Canty T (1999): Management of pediatric
liver injuries: A 13 year experience at a pediatric trauma
center.J Ped Surg 34:811-817.
29-Cote C, Todres D, Goudsouzian N, Ryan J (eds) (2001): A
Practice of Anesthesia for Infants and Children. WB
Saunders,Philadelphia, PA.
ANESTHETIC CONSIDERATIONS FOR PEDIATRIC CHEST TRAUMA
Hala samir El Mohamady, MD
Dept. of Anesthesiology, Intensive Dare, and Pain management, Faculty of Medicine, Ain Shams University
Abstract
Thoracic trauma is a major cause of morbidity and mortality in children.
The anesthesiologist needs to be prepared to manage such pediatric patient who may have severe multisystem injuries
with underlying respiratory derangements, ongoing blood loss, and cardiac dysfunction.
Many principles used in adult patients can be applied in pediatric patients; however the unique anatomy and physiology
of children must always be remembered.
For pediatric patients timely resuscitation and optimal care to avoid secondary injury is a considerable challenge for any
anesthesiologists.
Prevention of childhood injury remains the cornerstone of reducing the number of children who present for posttraumatic
surgical intervention. Beyond prevention, the next best step is the accurate diagnosis and treatment of
traumatic injury. Anesthesiologists contribute to this step by providing timely resuscitation and optimal care to avoid
secondary injury.
Introduction
Blunt and penetrating chest trauma is a major cause of
morbidity and mortality in children. Most pediatric
cases are caused by blunt trauma while penetrating
trauma is more common in adolescent boys.
Fortunately, children have an extremely compliant
body that may absorb considerable force and energy
with minimal external signs of injury. Conversely,
external signs of injury or rib fractures are an indicator
of significant potential soft tissue damage (1, 2). Young
children are less mineralized and more pliable, and
they tend to bend, but not break. Significant
intrathoracic injuries often occur without rib fractures;
however, the risk of mortality increases with the
number of ribs fractured (3) .Also Mortality from chest
trauma increases with the presence of abdominal (20%)
or head injury (35%) (4).
Evaluation and Management
Airway
Just as in the adult, the initial assessment should
concentrate on the A, B, C's (airway, breathing, and
circulation). It is important to remember the differences
in the pediatric airway, which include a large occiput,
large tongue, anterior larynx;
floppy, stiff Q-shaped epiglottis, and short trachea.
Unlike the adult, the cricoid is the narrowest part of
airway and so intubated patients should have a leak
around the endotracheal tube (ETT). The large tongue
and floppy epiglottis can contribute to airway
obstruction in an unconscious child. Appropriate jaw
thrust can lift the tongue off the back of the pharynx
and minimize airway compromise. A shoulder roll may
be required to place the head in an optimal position for
intubation; however, the presence of possible cervical
spine injury may preclude its use (5).
Any child that presents with respiratory compromise
should immediately receive supplemental oxygen with
continuous oxygen saturation monitoring. A changing
or altered mental status may indicate a closed head
injury, or severe hypovolemia.
Intubation should be considered in any child who is
combative, unconscious, or obtunded, to maintain
cerebral oxygenation and perfusion and to help
decrease the risk of secondary brain injury.
Infants and neonates are obligate nose breathers, so
occluded nasal passages from maxillofacial, neck, or
head trauma may prevent them from breathing
effectively.
Oral intubation is preferable to nasal intubation
because it is easier, faster, and less likely to result in
bleeding. Up to 50% of all pediatric trauma patients
will have brain trauma, including possible basilar skull
fracture. The cervical spine must always be protected
and the neck collar should remain in place until the
physician is absolutely sure there is no neck injury. Inline
stabilization (not traction) should be applied while
the patient is being intubated to prevent further spinal
cord injury (6). All pediatric trauma patients should be
considered at risk for aspiration particularly one with
thoracic injuries, rapid sequence induction with cricoid
pressure should be used until the airway is secured.
Cricoid pressure may destabilize an unstable neck in a
small child or infant and should be applied carefully by
experienced personnel. The ideal ETT should have a
leak at pressure <20-25 cm H20 if patient has normal
lungs. In patients with severe pulmonary trauma, a
larger ETT or cuffed ETT will facilitate ventilation. In
these patients, a leak at pressure 25-30 cm H20 will
maximize ventilation without increasing the risk of
developing subglottic stenosis (5).
Breathing
The trachea can be easily compressed; nasal flaring,
use of accessory muscles, and a "rocking boat" pattern
Ain Shams Journal of Anesthesiology Vol 2; Jan 2009
41
may indicate tracheal obstruction. The obstruction may
need to be relieved by intubation. Very rarely,
percutaneous cricothyrotomy or tracheotomy may be
required. Infants and small children are much more
dependent on diaphragmatic movement for respiration.
Anything that decreases the efficacy of diaphragmatic
motion will interfere with adequate breathing in these
patients (e.g. abdominal trauma and incorrectly
performed bag and mask ventilation. A nasogastric
tube should be expeditiously placed to deflate the
stomach.
The mediastinum in young children is very mobile and,
in the presence of a pneumothorax or hemothorax, can
easily allow compression of the heart and great vessels,
leading to a tension pneumothorax. Treatment for
pneumothorax is decompression with either a needle
placed at the mid-clavicular line of the second
intercostal space or placement of a chest tube (7).
Circulation
A change in blood pressure (BP) occurs only after there
is a 30% to 40% decrease in estimated blood volume
(EBV); therefore, BP is not a very good measure of
circulatory status. On the other hand, hypotension
indicates significant blood loss.
A systolic blood pressure of 90 mmHg or less in a child
is considered a predictive indicator of major trauma (8).
Early signs of hypovolemia include persistent
tachycardia, delayed capillary refill, and diminished
pulse pressure. Central pulses should be strong. An
absent or decreased radial pulse indicates
approximately a 10% reduction in intravascular
volume. Weakened axillary or femoral pulses signify a
loss of about 15%. It is important to calculate estimated
blood volume as soon as possible (Table 1).
Balanced salt solution (lactated Ringers or normal
saline 20 mL/kg) is most commonly used for volume
resuscitation. If there is minimal or no response to this
bolus, then an additional 2 boluses can be given while
preparations are being made to transfuse blood. The
initial dose of blood is 10 mL/kg of packed red blood
cells.
Table 1: Estimated Blood Volume in Children (2)
neonate -90 mL/kg
infant - 80 mL/kg
child -70 mL/kg
Estimated wt = (age x 2) +10
Intravenous access can often be difficult to establish in
a small child. It may be necessary to cut down on the
saphenous vein or place an intraosseous line. Femoral
lines are usually the easiest and least risky central lines
to place in these situations. The presence of a cervical
collar or possible neck injury may prevent access to the
internal jugular or subclavian vein (8).
Central Nervous System
The presence of head trauma in a patient with chest
trauma is a significant predictor of mortality. The
Glasgow Coma Scale (GCS) is not reliable in children
under 1 year of age because spontaneous motor
movements after CHI are common, which can
artificially elevate the, GCS also children may not be
able to cooperate and follow commands because of
their age or level of anxiety (9).
Specific Injuries
Pulmonary Contusion
pulmonary contusion (or lung contusion) is the most
frequent injury caused by chest trauma. It is usually
caused by blunt trauma but also explosions or a shock
wave associated with penetrating trauma can cause
lung contusion (10, 11).
Pathophysiology
Pulmonary contusion results in bleeding and fluid
leakage into lung tissue, which can become stiffened
and lose its normal elasticity. The water content of the
lung increases over the first 72 hours after injury,
potentially leading to frank pulmonary edema in more
serious cases. As a result of these and other
pathological processes, pulmonary contusion
progresses over time and can cause hypoxia. The larger
the area of the injury, the more severe respiratory
compromise will be (12).
Ventilation/perfusion mismatch
Normally, the ratio of ventilation to perfusion is about
one-to-one; the volume of air entering the alveoli
(ventilation) is about equal to that of blood in the
capillaries around them (perfusion). This ratio is
reduced in pulmonary contusion; fluid-filled alveoli
cannot fill with air, oxygen does not fully saturate the
hemoglobin, and the blood leaves the lung without
being fully oxygenated. Insufficient inflation of the
lungs, which can result from inadequate mechanical
ventilation or an associated injury such as flail chest,
can also contribute to the ventilation/perfusion
mismatch. So the mismatch between ventilation and
perfusion grows, blood oxygen saturation is reduced
(13). Pulmonary hypoxic vasoconstriction, in which
blood vessels near the hypoxic alveoli constrict in
response to the lowered oxygen levels, can occur in
pulmonary contusion. The vascular resistance increases
in the contused part of the lung, leading to a decrease
in the amount of blood that flows into it (14), directing
blood to better-ventilated areas. Although reducing
blood flow to the unventilated alveoli is a way to
compensate for the fact that blood passing unventilated
alveoli is not oxygenated, the oxygenation of the blood
remains lower than normal. If it is severe enough, the
hypoxemia resulting from fluid in the alveoli cannot be
Anesthetic considerations for Pediatric Chest Trauma El Mohamady HS
42
corrected just by giving supplemental oxygen; this
problem is the cause of a large portion of the fatalities
that result from trauma (13) .
Management
No treatment is known to speed the healing of a
pulmonary contusion; the main care is supportive (14)
Attempts are made to discover injuries accompanying
the contusion to prevent additional injury, and to
provide supportive care while waiting for the contusion
to heal (19). Monitoring, including keeping track of fluid
balance, respiratory function, and oxygen saturation
using pulse oximetry is also required as the patient's
condition may progressively worsen. Monitoring for
complications such as pneumonia and acute respiratory
distress syndrome is of critical importance (15).
Treatment aims to prevent respiratory failure and to
ensure adequate blood oxygenation (16) . The child with
mild pulmonary contusions may not need more than
good pain control, supplemental oxygen, observation,
pulmonary toilet, and early mobilization (17). More
severe injuries will be progressively more difficult to
treat. The presence of intrapulmonary shunts and
decreased compliance may necessitate mechanical
ventilation and positive end-expiratory pressure
(PEEP) (17). Overhydration can exacerbate edema and
worsen oxygenation; hypovolemia can produce
hypoperfusion and increase the risk of multiorgan
failure. So maintenance of euvolemia is important.
Inotropic agents may be required in patients with
severe pulmonary contusion. The administration of
steroids in these patients can increase the risk of
pneumonia(18).When the contusion does not respond to
other treatments, extracorporeal membranous
oxygenation may be used, pumping blood from the
body into a machine that oxygenates it and removes
carbon dioxide prior to pumping it back in(19).
Rib Fractures
Rib fractures are present in approximately one third of
children who present with thoracic trauma. The
presence of rib fracture should alert the physician to the
possibility of other significant thoracic and
extrathoracic injuries. The severity of other injuries
increased with the number of ribs fractured, as did the
mortality. All children with at least 4 fractured ribs had
other injuries. Treatment consists of maximizing
oxygenation and ventilation as necessary, treatment of
associated injuries, and ensuring good analgesia.
Intravenous opioids, patient-controlled analgesia, or
epidural analgesia can all be effective. The technique
selected will depend on the patient's underlying
condition and age (20).
Airway Obstruction
Maxillofacial trauma or laryngotracheal injury can lead
to airway obstruction. Patients may present with
hoarseness, stridor, subcutaneous emphysema, or
intercostals or sternal retractions. Injuries to the great
vessels in the neck can result in an expanding
hematoma that may compromise the airway.
Management includes jaw thrust, clearing of debris
from the oropharynx, intubation as necessary and
rarely, a cricothyrotomy or tracheostomy (21, 17) .
Pneumothorax
Pneumothorax is the most common immediately or
potentially life-threatening thoracic injury in a child.
Children higher rate of oxygen consumption and
smaller functional residual capacity makes them more
susceptible to hypoxia. The highly mobile and
compliant mediastinum in children allows the
mediastinal contents to shift to the contralateral side,
which can compromise blood return and cardiac output
so decompression of the tension pneumothorax is life
saving.
Definitive treatment is with a chest tube. The
pneumothorax may be stable until positive pressure
ventilation is instituted. Any patient who becomes
hypoxic and/or hypotensive after institution of positive
pressure ventilation, should be considered to have a
tension pneumothorax until proven otherwise.
Persistent air leak after the placement of appropriate
chest tubes may indicate a tracheobronchial tree injury.
One-lung ventilation is often necessary and can be
tricky in a small, unstable patient when operative repair
is needed (7).
Hemothorax
Pulmonary hematoma or massive hemorrhage is rare
unless accompanied by laceration to a vessel as their
lung has high levels of tissue thromboplastin and low
circulatory pressure, thereby limiting bleeding from
parenchymal injuries.
Unexplained hypotension, or chest tube output that is
initially greater than 15 mL/kg or continued bleeding
of 2-3 mL/kg/hr consider hemothorax and chest
exploration may be needed(22).
Traumatic Aortic Rupture
Injury to the great vessels has been shown to increase
mortality to more than 50%. Diagnosis of aortic rupture
is made by history and aortography. Tracheal deviation
to the right, and unequal blood pressures in the arms
may be signs of aortic rupture. On chest radiograph, a
widened mediastinum, abnormal contour of the aortic
knob, nasogastric tube deviation to the right,
depression of the left main bronchus, left hemothorax
may indicate aortic rupture necessitating urgent
exploration (23).
Flail Chest
Immediate treatment consists of applying pressure to
the flail segment to reduce chest wall instability and
minimize circulatory and ventilatory impairment. Most
Ain Shams Journal of Anesthesiology Vol 2; Jan 2009
43
children will require internal stabilization with
endotracheal intubation and mechanical ventilation.
Fluid restriction after initial resuscitation and insurance
of adequate gas exchange will minimize complications
(24) .
Myocardial Contusion and Other Cardiac Injuries
Cardiac trauma in children is relatively uncommon.
The severity of injury can vary from cardiac
concussion, which has no histologic manifestations and
is transient, to myocardial muscle or valve rupture.
These children will usually be unstable and mortality is
high (24, 25). The most common ECG abnormalities
included persistent sinus tachycardia, ST-T wave
abnormalities, conduction abnormalities, and
premature ventricular contractions (26).
Cardiac Tamponade
Cardiac tamponade is much more common with
penetrating injuries. The classic finding of Beck's triad
(muffled heart tones, increased central venous pressure,
decreased blood pressure) may be difficult to
appreciate in the small, hypovolemic child. Most
penetrating cardiac injuries will present with
hemopericardium and tamponade. Treatment is with
pericardiocentesis (7).
Anesthetic Management
Approximately 20% will require operative intervention
because of abdominal injuries, which may be
associated with massive blood loss (27).
A patient that is not already intubated, should undergo
a rapid sequence induction with cricoid pressure.
Children can desaturate much more quickly than
adults, so a modified rapid sequence induction is often
preferable. Cricoid pressure will need to be applied
carefully in the child with an unstable neck. Most of
these patients will be volume depleted and resuscitation
will be ongoing.
Induction agents that do not decrease blood pressure or
heart rate should be chosen. Ketamine or etomidate are
good choices, although small doses of thiopental or
propofol can be used in more stable patients,
particularly if they have an associated head injury (28) .
Standard monitors should be applied. Pulse oximetry
may be difficult to obtain in a small, cold
vasoconstricted patient; therefore, it is prudent to use
multiple probes in several locations. Respiratory
variation in the waveform of the pulse oximeter may
indicate hypovolemia. Bradycardia usually indicates
hypoxia, ischemia, acidosis, or hypothermia and should
be rapidly corrected. Persistent tachycardia can signify
hypovolemia and acute blood loss. End tidal carbon
dioxide (ETCO2) is less accurate in smaller patients
because they have a relatively higher dead space to
tidal volume ratio than adults. Hypovolemic patients
will have even more dead space, and patients with
thoracic injuries may have increased shunting as well.
A low ETC02 may reflect low cardiac output, because
there is less blood flow to lungs (29).
At least 2 intravenous (IV) catheters should be placed,
preferably one above and one below the diaphragm,
and blood obtained for crossmatch.
If there is difficulty obtaining peripheral IV access, a
central venous or intraosseous catheter can be placed.
Femoral venous catheters are often the easiest to get
access to, have easy landmarks and the lowest
complication rate. A subclavian catheter should always
be placed on the side of the suspected injury, especially
if there is already a chest tube on that side. Maintaining
body temperature with radiant warming lights, warm
fluids, or a forced air warmer is critical. Hypothermia
and vasoconstriction can increase coagulopathy and
bleeding, adversely affecting perfusion. Small children
have a large body surface area to mass, and
temperature control can be exceptionally difficult.
Actively warm patients if they arrive cold. The only
exception is in patients with severe closed head injury,
in whom mild hypothermia is preferred. Rewarming
may lead to increased acidosis (rewarming shock).
Invasive blood pressure monitoring will be important
and can be challenging to place. It may be necessary to
cut down on the radial artery, or to place the catheter in
the femoral, axillary, dorsalis pedis, or post tibial
arteries.
The presence of significant hypovolemia can cause
hypoperfusion and metabolic acidosis. Once
resuscitation has started, perfusion may occur to
previously underperfused areas, causing washout of
acid, vasodilatation, decreased cardiac output, and
continuing hypotension. Metabolic acidosis usually
improves with fluid resuscitation. However, in patients
with severe trauma, the acidosis may need to be treated
with sodium bicarbonate, as long as ventilation is
adequate. The Dose of bicarbonate is wt (kg) x 0.15 x
base deficit. However, since many of these patients
will have a base deficit of more than 10 mEq/L, 2 x
weight is a good starting dose.
The fluids most often used in resuscitation in children
are balanced salt solution (lactated Ringers or
Plasmalyte) or albumin.
Blood should be available and the child should be
transfused for the same indications as in adults.
Consider administration of fresh frozen plasma (FFP)
and platelets after the equivalent of 1 to 2 estimated
blood volumes have been transfused. FFP has the
highest citrate content per unit. Citrate binds with
calcium, so severe hypocalcemia may develop (citrate
intoxication) especially if FFP is administered rapidly.
Citrate toxicity is treated with calcium chloride (CaCl2)
10 mg/kg or calcium gluconate 30 mg/kg.
Hyperkalemia can occur as a result of massive blood
transfusion. One-week-old blood contains 5 mEq/L
potassium; while three-week-old blood, has 22 mEq/L
potassium. In a small child, this amount of potassium
may be significant. Treatment is with CaCl2 10 mg/kg,
Anesthetic considerations for Pediatric Chest Trauma El Mohamady HS
44
hyperventilation, and bicarbonate. If hyperkalemia
persists then glucose (0.5 gm/kg) and insulin (1
unit/5gms glucose) can be administered (7).
REFERENCES:
1- Ross AK: Pediatric trauma (2001). Anesthesia management.
Anesthesiol Clin North America;19(2):309-37.
2- Tepas JJ: Pediatric Tepas JJ (1996). Pediatric Trauma, in
Feliciano, Morre, Maddox (eds): Trauma. Norwalk, Appleton
& Lange, pp 1075-1096.
3-. Garcia VF, Gotschall CS, Martin MA (1990): Rib fractures in
children:A marker of severe trauma. J Trauma 30:695-700.
4- Peng RY, Bongard FS (1999): Pedestrian versus motor vehicle
accidents:An analysis of 5,000 patients. J Am Coll Surg
189:343-348.
5- Mazurek AJ, Hall SC: Pediatric Trauma in Cote, Todres,
Goudsouzian and Ryan (eds) (2001): A Practice of Anesthesia
for Infants and Children. WB Saunders,
Philadelphia,Pennsylvania, pp 334-352.
6-. Mazurek AJ, Hall SC: Pediatric Trauma in Cote,
Todres,Goudsouzian and Ryan (eds) (2001): A Practice of
Anesthesia for Infants and Children. WB Saunders,
Philadelphia,Pennsylvania, pp 334-352.
7- Rita Agarwal: Anesthesia for Pediatric Chest Trauma (2002).
Seminars in Cardiothoracic and Vascular Anesthesia, Vol 6, No
2 (June), 83-94.
8- Engum SA, Mitchell MK, Scherer LR (2000): Prehospital triage in
the injured pediatric patient. J Ped Surg 35:82-87.
9-. Hall JK, Berman JM (eds) (1996): Pediatric Trauma Anesthesia
and Critical Care. Futura Publishing Company, Inc, Armonk,
New York.
10- Moloney JT, Fowler SJ, Chang W (2008): "Anesthetic
management of thoracic trauma" Current Opinion in
Anaesthesiology 21 (1): 41–46.
11-Sasser SM, Sattin RW, Hunt RC, Krohmer J (2006): "Blast lung
injury". Prehospital Emergency Care 10 (2): 165–72.
12- Ullman EA, Donley LP, Brady WJ (2003): "Pulmonary trauma
emergency department evaluation and management".
Emergency Medicine Clinics of North America 21 (2): 291–
313.
13 -Kishen R, Lomas G (2003): "Thoracic trauma", in Gwinnutt CL,
Driscoll P: Trauma Resuscitation: The Team Approach.
Informa Healthcare, 55–64.
14- Bastos R, Calhoon JH, Baisden CE (2008): "Flail chest and
pulmonary contusion". Seminars in Thoracic and
Cardiovascular Surgery 20 (1): 39–45.
15- Sutyak JP, Wohltmann CD, Larson J (2007): "Pulmonary
contusions and critical care management in thoracic trauma".
Thoracic Surgical Clinics 17 (1): 11–23.
16- Moloney JT, Fowler SJ, Chang W (2008). "Anesthetic
management of thoracic trauma". Current Opinion in
Anaesthesiology 21 (1): 41–46.
17-Ruddy RM (2005). "Trauma and the paediatric lung". Paediatric
Respiratory Reviews 6 (1): 61–67.
18- Petersen MD, Henderson B (1996): Thoracoabdominal Trauma,
in JK Hall, JM Berman (eds): Pediatric Trauma Anesthesia and
Critical Care. Armonk, NY, Futura Publishing Co, Inc, pp 245-
273.
19-. Cooper A (1995). Thoracic injuries. Semin Pediatr Surg 4:109-
116.
20- Pettiford BL, Luketich JD, Landreneau RJ (2007). "The
management of flail chest". Thoracic Surgery Clinics 17 (1):
25–33.
21-. Reilly JP, Brandt ML, Mattox KL (1998): Thoracic trauma in
children.J Trauma 34:329-331.
22- Scherer LR: Thoracic Trauma, in Oldham KT, Colobani
PM,Fogalis RP (eds) (1997): Surgery of Infants and Children:
Scientific Principles and Practice. Lippincott-Raven,
Philadelphia, PA, pp 455-461.
23- Cooper A (1995). Thoracic injuries. Semin Pediatr Surg 4:109-
116.
24- Cox CS, Black TB, Duke JH, et al (1998): Operative treatment of
truncal vascular injuries in children and adolescents. J Ped Surg
33:462-467.
25- Stafford PW, Harmon CM (1993): Thoracic trauma in children.
Current opinion. Pediatrics 5:325-332.
26- Baum VC (2002): Cardiac trauma in children. Paed Anesth 12:
110-117.
27- Hirsch R, Landt Y, Porter S (1997): Cardiac troponin 1 in
pediatrics:Normal values and potential use in the assessmentof
cardiac injury. J Pediatrics 130:872-877.
28- Gross M, Lynch F, Canty T (1999): Management of pediatric
liver injuries: A 13 year experience at a pediatric trauma
center.J Ped Surg 34:811-817.
29-Cote C, Todres D, Goudsouzian N, Ryan J (eds) (2001): A
Practice of Anesthesia for Infants and Children. WB
Saunders,Philadelphia, PA.
Thursday, October 28, 2010
Tuesday, October 26, 2010
paravertebral block
Thoracic Paravertebral Block
Joe Loader, Pete Ford*
The thoracic paravertebral
block was first described
in the treatment of chronic
pain. More recently, the
technique has also been
used to provide surgical
analgesia for a variety of
applications, including
thoracic, breast, and general
surgery. It is possible to
provide analgesia lasting into
the postoperative period,
and certain procedures may
be performed without the
need for general anaesthesia.
spinal column. The space is defined medially
by the vertebral body and the intervertebral disc and
foramina, antero-laterally by the pleura and posteriorly
by the superior costotransverse ligament, running
between adjacent transverse processes. Above and below,
the space communicates freely with adjacent levels. The
paravertebral space is also in communication with the
vertebral foramina. The ventral and dorsal primary rami
traverse the space, carrying sensory afferents and form
the spinal nerves. In addition, the space contains the
sympathetic trunk which communicates with the spinal
nerves via the gray and white rami communicantes.
Thus local anaesthetics introduced into this space may
produce sensory, motor and sympathetic blockade over
several dermatomes.
TECHNIQUE FOR PVB
Obtain consent before starting. It is essential to ensure that full
resuscitation facilities are available and that monitoring including
ECG, pulse oximetry and blood pressure measurement is in place.
Intravenous access should be secured.
Equipment
Skin preparation (e.g. chlorhexadine 2%), skin marker, Tuohy needle
(22G), extension tubing, 20ml Leur-lock syringe, 0.5% bupivacaine
PVB may be performed awake, in which case the sitting position may
be preferable, or with the patient anaesthetised in the lateral position.
The site of surgery determines the level of PVB as shown in Table 1.
Table 1. Dermatomal sites for different surgical procedures
Surgery Dermatomes Level of PVB
Thoracotomy T3 – T9 T3 – T9
Breast surgery T1 – T6 T1 – T5
Cholecystectomy T4 – L1 T6 – T12
Inguinal herniorrhaphy T10 – L2 T10 – L2
Use the scapula and the processus prominens as landmarks. The
processus prominens is the most prominent upper thoracic vertebral
prominence and is the spinous process of T1. The most inferior
palpable part of the scapula lies at the level of T7.
Locate the spinous processes corresponding to the required levels
of block and make a mark 2.5cm lateral to each of them (Figure 3).
Under aseptic conditions, a skin wheal of local anaesthetic is placed
at each mark. If sedation is used, then supplemental oxygen should
be administered.
A B
If bone is not contacted, the needle should be withdrawn and redirected
superiorly, and if still not successful, inferiorly.
When the needle contacts bone, the depth is noted, the
needle is then withdrawn and re-directed inferiorly to ‘walk-off’ 1cm
past the inferior edge of the transverse process. A ‘click’
can sometimes be felt as the needle passes through the superior
costotransverse ligament. It is imperative to locate the transverse
process before advancing the needle any further to prevent inadvertent
pleural puncture.
To increase the duration of the block it is possible to insert a catheter
and run a continuous infusion or administer intermittent boluses of
local anaesthetic.
ADVANTAGES OF PVB
• Simple and quick to learn
• Avoids the potential complications of a thoracic epidural
• Reduced postoperative pain
• Lower postoperative analgesic requirements
• Reduced postoperative nausea
• Reduced incidence of chronic pain after breast surgery.
CONTRAINDICATIONS
Absolute
• Cellulitis or cutaneous infection at site of needle puncture
• Empyema
• Tumour occupying the paravertebral space
• Allergy to local anaesthetic drugs.
Relative
• Coagulopathy
• Kyphoscoliosis - deformity may predispose to pleural puncture
• Previous thoracotomy - scarring may cause adhesions to the parietal
pleura and increase the risk of pneumothorax.
COMPLICATIONS
• Sympathetic blockade and hypotension
• Horner’s syndrome is frequent, short duration and of no lasting
consequence, but patients should be warned. Incidence is between
5 and 20%
• Vascular puncture
• Haematoma
• Pneumothorax. The incidence is between 0.01 to 0.5%. Risk of
bilateral pneumothorax should be considered if performing bilateral
blocks. If pleural puncture occurs, a chest radiograph should be
obtained to exclude pneumothorax A chest radiograph is not
routinely required otherwise.
• There is one single report of a haemothorax, using a loss of resistance
technique
Sunday, October 24, 2010
VIDEO ASSISTED THORACOSCOPIC SURGERY
VIDEO ASSISTED THORACOSCOPIC SURGERY
Principles of thoracoscopic surgery
The minimal requirement for VAT are: rigid telescope, a light source with cable, a camera and an image processor.
The optimal devices are: slave monitor, semiflexible telescope and a video recorder.
- VATS require high light output power as blood is in the operative field absorb 50% of the light.
- The access site must be placed at sufficient distance from the target pathology to allow for adequate room.
- The thoracic is rigid and the access sites are limited to the intercostals space.
- Single lung anesthesia is necessary to deflate the lung’
- All movement should be under direct vision to prevent damage to surrounding tissue.
- The surgeon should be able to handle complication and converting to open procedures.
- Specific instruments include stapling device, laser, dissectors and retractors.
Indications
The common indications are:
1. Cancer staging
2. Diagnosis of pleural disease
3. Management of persistent pneumothorax, retained hemothorax, infected pleural space including empyema
4. Pericardial drainage
5. Thoracic sympathectomy
with surgical advances other indications have been added to the list:
with surgical advances other indications have been added to the list:
· Thoracic duct ligation
· Removal of thoracic cyst
· Vagotomy
· Lobar resection
· Esophageal surgery
Contraindications
1. Pleural symphysis caused by previous thoracic surgery or pleurodesis
2. Bleeding disorders
3. End stage pulmonary fibrosis
4. Respiratory insufficiency and hempdynamic instability
Advantages
1. Shorter length of hospital stay
2. Less postoperative pain
3. Preserved pulmonary function
4. Superior cosmotic result
5. Shorter recovery time
Anesthetic management of VATS
Preoperative evaluation
Preoperative evaluation
A thorough history and physical exam with special attention to the cardiorespiratory status is necessary for all patients. Routine lab investigation include full blood count, electrolyte levels, ECG, chest radiograph and CT scan help to make diagnosis and identify potential problems. Spirometry tests include FVC
FEV₁
FEV₁ // FVC
Preoperative optimization of respiratory function is achieved by bronchodilator, cessation of smoking, incentive spirometry and physiotherapy.
Intraoperative management
The goals of anesthesia include maintaining stable cardiovascular function, optimizing oxygenation and ventilation, minimizing airway reactivity and preventing respiratory depression in the postoperative period.
Monitoring
In addition to standard monitoring techniques, invasive arterial pressure and central venous pressure monitoring may be needed in patient with limited cardio-respiratory reserve.
Anesthetic techniques
Thoracoscopic surgery has been performed under local, regional or general anesthesia
- General anesthesia is usually induces with an IV agent such as propofol or thiopentone and maintained with inahalational agent in air/O2 misture
N2O is preferably avoided because of the risk of expansion of air filled spaces.
Advantage of inhalation agents to be mentioned
Narcotic analgesia attenuate stress response, reduce requirement of inhalational agent and produce analgesia
- Most VAT require patient to be placed in lateral decubitus position.
- One lung anesthesia is required
- Postoperative analgesia strategies include oral opioids, PCA, local anesthetic infiltration, intercostals block, paravertebral block and epidural analgesia.
- Post op care
- Carbon dioxide insufflations
It may be used to accelerate lung deflation.
Rapid or excessive insufflations of the gas may cause mediastinal shift resulting in hemodynamic instability, bradycardia, hypertension, hypoxia and surgical emphysema.
Gas flow is restricted to 2L/m with the pressure limited to 10mmHG
Complications
o hypoxemia caused by v/p mismatch
o Chest pain caused by thermal damage to the parietal pleura and the periosteum over the ribs.
o Respiratory complication: sputum retention, atelectasis
o bleeding due to injury to blood vessels or lung perforation.
CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD)
COPD is characterized by the progressive development of airway limitation that is not fully reversible.
The term COPD encompasses chronic bronchitis and emphysema.
Chronic bronchitis is defined as the presence of a productive cough for more than 3 months for more than 2 successive years.
Chronic bronchitis follows prolonged exposure of the airways to non specific irritant and characterized by hypersecretion of mucous and inflammatory changes in the bronchi.
Pulmonary emphysema is defined as enlargement of air spaces and destruction of lung parenchyma, loss of lung elasticity, and closure of small airways. Obstruction to expiratory airflow can also lead to the formation of bullae with compression of the adjacent lung tissues.
Diagnostic and Clinical Features
A chronic productive cough and progressive exercise limitation are the hallmarks of persistent expiratory airflow obstruction.
Patient with predominant chronic bronchitis present with chronic productive cough, whereas patient with predominant emphysema complain of dyspnea
Chronic bronchitis emphysema
Mechanism of airway decreased airway lumen due loss of elastic recoil of the
Obstruction to mucous and inflammation lung
Dyspnea moderate severe
FEV₁ decreased decreased
PaO2 marked decrease moderate decrease
(blue bloater) (pink buffer)
PaCO2 increased normal - decrease
Diffusing Capacity normal decreased
HT increased normal
Corpulmonale marked mild
Prognosis poor good
Pulmonary Function tests
Pulmonary Function tests reveal
1. Decrease in FEV₁ / FVC ration
2. Decrease in F. expiratory flow
3. Increase in RV and normal to increase FRC, TLC
Chest Radiography
Radiologic abnormalities may be minimal but it meight show
· Hyperlucency and hyperinflation
· Flattening of the diaphragm
· Very vertical cardiac silhouette
· Emphasematous bullae
ABG
ABG can be used to categorize patient with COPD as
Pink buffers
PaO2 usually high than 60mmHg and PaO2 is normal
Individual characterized as pink buffers are typically thin and free of signs of right heart failure and have severe emphysema.
Blue bloaters
PaO2 usually less than 60mmHg and
PaCO2 chronically increased to more than 45mm
Blue bloater typically exhibit cough and sputum production
Consequences of these two Arterial BIood Gas pattern
Blue bloater:
Arterial hypoxemia and respiratory acidosis lead to increase in pulmonary vascular resistance with resultant pulmonary hypertension.
Chronic pulmonary hypertension cause right ventricular hypertrophy and failure (Cor pulmonale) arterial hypoxemia also cause secondary erythrocytosis.
Pink buffers:
Loss of pulmonary cap. Vascular bed decrease
Lung diffusing capacity.
Since paO2 is only mildly decrease, pulmonary V.C. is minimal and erythrocytosis does not occur.
Spirometric Classification of COPD
0: at risk normal spirometry
Chronic sympt
FEV₁ / FVC ˂ 70%
I: mild FEV₁ ≥ 80% of predicted
with or without chronic symptoms
II: moderate FEV₁ / FVC ˂ 70%
50% ˂ FEV₁ ˂ 80%
with or without symptoms
III: severe FEV₁ / FVC ˂ 70%
FEV₁ 30-50% of predicted
With or without chronic symptoms
IV: very severe FEV₁ / FVC ˂ 70%
FEV₁ ˂ 30%
FEV₁ ˂ 50% + chronic respiratory failure
Treatment of COPD
1. Cessation of smoking and supplemental O2
2. Drug therapy
- Bronchodilator, β agonist, anticholinergic, antibiotics
3. Lung volume reduction surgery
Anesthetic management of patient with COPD
Preoperative management
The history and physical examination of patient with COPD provide more accurate assessment of the likelihood of post-op pulmonary complications.
A history of poor exercise tolerance, chronic cough or unexplained dyspnea combined with diminished breath sounds, wheezing and prolonged expiratory phase predict an increased risk of post-op pulmonary complications.
Preop pulmonary Functions tests
The results of pulmonary function tests and ABG can be useful for predicting pulmonary function after lung resection but they do not reliably predict the likelihood of post-op pulmonary complications after non-thoracic surgery.
Indications for pre-op tests typically include:
1. Hypoxemia on room air or the need for home oxygen therapy without a known etiology
2. Bicarbonate more than 33mEq/L or PaCO2 ˃ 50mmHg
3. History of respiratory failure
4. Severe shortness of breath due to respiratory disease
5. Planned pneumonectomy
6. Determining the response to bronchodilator
7. Suspected pulmonary hypertension
Risk reduction strategies
1. Preoperative
- Encourage cessation of smoking for at least 6 weeks
- Treat evidence of expiratory airflow obstruction
- Treat respiratory infection with antibiotics
- Patient education regarding lung expansion maneuver’s
2. Intraoperative
- Use of minimally invasive surgical technique
- Consider use of regional anesthesia
- Avoid prolonged surgery ˃ 3 hours
3. Postoperative
- Institute lung expansion maneuvers (voluntary deep breathing, incentive spyrometry, CPAP)
- Maximize analgesia
Acute effects of smoking cessation
The adverse effects of CO on oxygen carrying capacity and effects of nicotine on the cardiovascular system are short lived.
- The elimination half life of CO2 is approximately 4-6h when breathing room air.
Within 12h after cessation of smoking the PaO2 at which Hb is 50% saturated increase from 22.9 to 26.4mmHg and plasma level of carboxyHb decrease from 6.5% to 1%
- The sympathomimetic effects of nicotine on the heart are transient, lasting only 20-30mins.
- Other long term benefits of smoking cessation include: improvement in ciliary function, decrease in sputum production
Intraoperative management
Regional anesthesia is suitable for lower intra-abdominal and lower extremities procedures. However, regional anesthetic techniques that produce sensory anesthesia above T6 are not recommended as they may impair the ventilatory functions requiring active exhalation such as expiratory reserve volume, peak expiratory flow and maximum minute ventilation. Clinically this is manifested as a cough that is inadequate to clear airway secretions.
Loss of proporioception from the chest, and unusual position like lithotomy or lateral position, often accentuate dyspnea in awake patient.
It must be appreciated that COPD patient can be extremely sensitive to the ventilator depressed effects of sedative drugs. When used, it should be given in small incremental doses.
- General Anesthesia
General anesthesia is often provided with volatile anesthetics. Volatile anesthetics produce bronchodilatation and have ability to be rapidly eliminated through the lung minimizing postop resifual ventilator depression.
Nitrous oxide should be avoided in patient with bullae and patient with pulmonary hypertension. Opioids may be less desirable as they cause prolonged postop respiratory depression.
Ventilation should be controlled with small moderate tidal volume and slow rates to avoid air trapping humidification of inspired gases and use of low gas flow help to keep airway secretion moist.
Arterial CO2 measurement should be used to guide ventilation. Ventilation should be adjusted to maintain a normal arterial pH.
Hemodynamic onitoring should be dictated by any underlying cardiac dysfunction and the extent of surgery.
Postoperative management
Lung expansion maneuvers
They decrease the risk of atelectasis by increasing lung volumes.
They include:
Deep breathing exercises
Chest physiotherapy
Incentive spirometry
Positive pressure breathing techniques
Pain control
Postop. Neuroaxial analgesia with opioids may permit early tracheal extubation, early ambulation, which help to increase FRC and improve oxygenation.
Postoperative neuroaxial analgesia is recommended after high risk thoracic abdominal and major vascular surgery.
Mechanical ventilation
Continued mechanical ventilation during the immediate postop period may be necessary in patient with severe COPD who have undergone major abdominal or intra-thoracic surgery.
FiO2 and ventilator settings should be adjusted to maintain paO2 60-100mmHG and paCO2 in a range that maintains pH at 7.35 – 7.45.
The decision to discontinue mechanical ventilation and tracheal extubation is based on the patient clinical status and indices of pulmonary function.
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