PULMONARY ARTERY PRESSURE MONITORING

PULMONARY ARTERY PRESSURE MONITORING

Pulmonary artery pressure monitoring is measuring the pressure in the pulmonary artery leading to the lungs. It also allows for indirect measurement of left heart pressures since the pulmonary veins have no valves in them and collects the information needed to calculate cardiac output and resistance. The PA catheter assesses all 3 components of stroke volume: preload, afterload, and contractility.

The catheter is 60-100 cm long and the caliber is 4-8 Fr (a standard suction catheter is 14 French)...the balloon will hold 0.5-1.5 ml of air and get 8-13 mm big when inflated
Distal Port:
• terminates in the pulmonary artery
• used to monitor pulmonary artery pressure and pulmonary capillary wedge pressure when the balloon is inflated
• provides a port for mixed venous blood samples
Balloon Inflation Port:
• used to inflate the balloon at the end of the PA catheter with no more than 1.5 ml of air
• has a locking device for safety
• is inflated during insertion to allow the catheter to float into correct position
• when inflated will measure pulmonary capillary wedge pressure, which is equal to the pressure in the left atrium and ventricle during diastole

Proximal Injectate Port:
• is usually blue in color
• provides a port for injecting fluid when measuring CO
• measures RA/CVP
• can be used as an IV infusion site if CVP monitoring not needed
Proximal Infusion Port:
• is usually white in color and AKA venous infusion port
• lumen opens into the RA
• can be used to infuse fluids or meds without interruption
• is not attached to the transducer

Cardiac Output Port:
• a white square port with pins that connects to the CO cable
• the CO cable connects to the monitor
• has temperature sensitive wires that terminate near the distal tip

• is used for thermodilution CO measurement

Other Ports:
• Pace Port for a ventricular or atrial pacemaker
• SvO2 monitoring port

Indications for PAP Monitoring:
• to assist in making a differential diagnosis
• to guide the management of the patient with heart/lung disease/shock of all types
• to monitor hemodynamic pressures during fluid resuscitation
• inotropic/vasoconstrictor/vasodilator drug infusion therapy
• to assess complications of MI and heart failure
• to monitor hemodyanamics with complicated surgical procedures

Contraindications:
• severe coagulopathy
• patient receiving thrombolytics (eg-TPA)
• prosthetic right heart valve - catheter may cause the valve to malfunction
• endocardial pacemaker - catheter may dislodge or knot around the electrode
• severe pulmonary hypertension - increased risk of PA rupture
• severe vascular disease - catheter may puncture an abnormal vessel
• significant immunodeficiency
• if there are no skilled physicians/staff
• if the patient's disease or injury can't be modified or corrected by therapy
TECHNIQUE OF INSERTION:

1. follow the steps of CVP catheter insertion.
2. then, the swan ganz catheter which has been filled with fluid and attached to transducer is passed to SVC.
3. location of the catheter tip in a central vein is confirmed by pressure changes to respiration or coughing. it should look like CVP tracings.
4. with  the catheter in the RV, the balloon is inflated with 1.5 ml of air and the catheter is advanced.

5. further advancement of the cathetr will produce a dramatic change in pressurefrom that of RA to RV in the range of 25/0 mmHg.
6. the catheter is advanced through RV until it enters the mean PA this can be recognised by an increase of diastolic pressure 25/12 mmHg.


7. the catheter is advanced further until it wedges in abranch of PA. it will usually have the appearance of arterial pressure pattarn with a, c, and v waves comonents transmitted retrogradely from LA.
8. PCW position is verified by the characteristic above mentioned waveform, a mean pressure slighty lower than mean PA pressure, and the ability to withdraw arterialised blood.
9. after achieving a wedge position, the balloon is deflated. this should produce a typical PA pressure tracing.

 Complications during insertion:

• pneumothorax
• venous air embolism
• dysrhythmias
• dislodgement of the catheter guide wire
• excessive bleeding

Complications after insertion:
• dysrhythmias - especially right bundle branch block/third degree block
• infection
• catheter dislodgement
• thrombophlebitis
• pulmonary rupture

Tension pneumothorax may occur if the pleura is punctured and/or the lung is perforated during insertion. Sudden hypotension, unequal breath sounds, respiratory distress, tracheal deviation, and increased PIP (if on the ventilator) are signs that a pneumothorax has occurred. Needle tap or chest tube placement should be performed as soon as possible.

Venous air embolism can occur as the person inhales while the needle is in the vein, if the end is open to the atmosphere. That's one reason why the doctor will put his finger over the hub of the needle once it's in the vein. You can have the patient perform a Valsalva maneuver while the catheter is being inserted to avoid this. If it occurs, the patient will become tachypneic with chest pain and hypotension. Roll them onto their left side and administer 100% oxygen.

Once the catheter is in position, get an x-ray to determine placement...the tip should be in  The mediastinum. If it's beyond the mediastinum, it's too far and may cause an error in the CO measurement or damage to the vessel. Most of the time the catheter will be in a zone 3 area of the lung, but it it's in zone 1 or 2 the PA pressure will be influenced by alveolar pressure. Since the tip is flow-directed into the lung, it will usually end up in zone 3, so the influence of PEEP is minimized. Remember, in zone 1 the capillaries are always closed, so the wedge would not be accurate because the capillaries wouldn't be open to the LA. In zone 2, the capillaries open during systole and close during diastole, so the pressures would change with systole/diastole. Only in zone 3 are the capillaries always open.

To draw blood from a pulmonary artery catheter, you must withdraw about 5 ml of waste very slowly and discard, then draw the sample, again very slowly. If you withdraw the blood too fast, the sample will be contaminated with arterial blood.

Wedging Protocol:
The frequency of wedging depends on the patient...if the wedge is correlating closely with the pulmonary artery diastolic pressure, then you don't need to wedge as often. The balloon should be slowly inflated with no more than 1.5 ml of air (and you may not need that much for the catheter to wedge).