Thoracic combined spinal-epidural (CSE) anaesthesia

Abstract

The experimental delivery of spinal anaesthetics to the desired heights in the body, even above the termination of the spinal cord (thoracic level), has been shown to be potentially very valuable. Since there is no blockade of the lower extremities, little caudal spread, a significantly larger portion of the body experiences no venal dilation, and may offer a compensatory buffer to adverse changes in blood pressure intra-operatively. Further, the dosing of the anaesthetic is exceedingly low, given the highly specific block to only certain nerve function along a section of the cord. Thirdly, the degree of muscle relaxation achievable without central or peripheral respiratory or circulatory depression is superior to that with general anaesthesia. Results from Magnetic Resonance Imaging (MRI) studies indicate that the spinal cord lies anteriorly within its thecal boundaries in the apex of the thoracic curve. Intrathecal injections, therefore, at thoracic levels may have a greater absolute margin of error before needle contact with neural tissue - although the consequences of inadvertent contact are possibly more disastrous. The thoracic CSE technique has been practised in twelve patients with cardiovascular and/or pulmonary problems. Despite bad haemodynamic situations and/or severe end-stage lung problems, abdominal surgery (i.e. cholecystectomy, bowel and vascular surgery) could be performed successfully with the thoracic CSE method, with low impact on the patient. Anaesthetic care of the patients would have been more difficult, with consequently larger impacts on haemodynamic and pulmonary function, should these surgeries have occurred under general anaesthesia - the usual anaesthetic technique of choice. CSE techniques can be used in the thoracic region in patients who otherwise would receive general anaesthesia. High risk patients, with limited cardio-respiratory reserves, present challenges to the anaesthesiologist. Using the thoracic CSE technique in the thoracic space is extending the boundaries of regional anaesthesia.