[Effects of cervical plexus block on lung ventilation].

BACKGROUND

Carotid endarterectomy is a preventative operation to reduce the incidence of embolic stroke. The prime concern during surgery is the protection of the brain during carotid artery cross-clamping. Since blood flow to the brain is provided via the non-affected carotid artery and collateral circulation, it is essential to maintain consciousness in the patient during surgery, in order to assess the effects of cross-clamping. Regional anaesthesia has therefore been regarded as the method of choice for this kind of surgery. Cervical plexus analgesia can be achieved at two levels: superficial--when skin branches of the plexus are blocked, and deep--when short and long nerves are blocked. Successful block of the cervical plexus depends of effective analgesia achieved at both levels. This can be achieved by a single injection as described by Winnie, or multiple injection at C2, C3 and C4 as described by Moore. Among possible complications, the most common is transient phrenic nerve block with diaphragm dysfunction.

METHODS

We have compared the effects of cervical plexus block performed according to Winnie (group W), or Moore (group M) on spirometry, arterial oxygen saturation and carbon dioxide tension, in seventy-five patients scheduled for endarterectomy.

RESULTS

Group W consisted of 44 patients, and group M--of 31 patients. VC, FVC, FEV1 and PIF decreased in all patients. There were no statistically significant differences between the groups. Transient paralysis of the diaphragm, confirmed by chest x-ray, occurred in 8 (19.5%) patients of group W, and in 4 (14.3%) patients of group M. Gas exchange remained unchanged.

CONCLUSIONS

We proved that cervical plexus block is associated with moderate depression of respiratory function without impairment of gas exchange. The block may be complicated by transient unilateral diaphragm paralysis.