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