Spinal anaesthesia produces few adverse effects on the respiratory system as long as unduly high blocks are avoided. As control of the airway is not compromised, there is a reduced risk of airway obstruction or the aspiration of gastric contents. This advantage may be lost if too much sedation is given. There is little risk of unrecognised hypoglycaemia in an awake patient. Diabetic patients can usually return to their normal food and insulin regime soon after surgery as they experience less sedation, nausea and vomiting.
Spinal anaesthesia provides excellent muscle relaxation for lower abdominal and lower limb surgery.
Blood loss during operation is less than when the same operation is done under general anaesthesia. This is because of a fall in blood pressure and heart rate and improved venous drainage with a resultant decrease in oozing. Splanchnic blood flow. Because it increases blood flow to the gut, spinal anaesthesia may reduce the incidence of anastomotic dehiscence. The bowel is contracted during spinal anaesthesia and sphincters are relaxed although peristalsis continues.