Anaesthesia for extracorporeal shock wave lithotripsy.

The anaesthetic considerations of patients presenting for extracorporeal shock wave lithotripsy are described. Regional anaesthesia with sedation may be preferable to general anaesthesia for patients undergoing this form of therapy. If regional anaesthesia is contra-indicated, general anaesthesia using controlled ventilation with muscle relaxation, supplemented with a narcotic and a low concentration of volatile anaesthetic has been found to be a suitable alternative. The additional epidural preparation time has to be balanced against the benefits of easier patient transfer, especially during multi-stage procedures, and better postoperative analgesia. The epidural catheter can be left in situ in patients who require multiple treatments or who may experience severe ureteric pain as the resulting 'sand mass' is passed. Epidural space localisation using a 'loss of resistance to saline' technique is recommended, in order to avoid the possible risk of damage to the spinal cord and emerging nerves (due to the presence of an air-water interface). Patients with cardiac insufficiency need special consideration, in view of the effects of immersion on right and left heart filling pressures.