As with general anaesthesia, continuous, close monitoring of the patient is mandatory. Some patients are not psychologically suited to be awake, even if sedated, during an operation. They should be identified during the preoperative assessment. Likewise, some surgeons find it very stressful to operate on conscious patients. Even if a long-acting local anaesthetic is used, a spinal is not suitable for surgery lasting longer than approximately 2 hours.
Patients find lying on an operating table for long periods uncomfortable.
If an operation unexpectedly lasts longer than this, it may be necessary to convert to a general anaesthetic or supplement the anaesthetic with intravenous ketamine or with a propofol infusion if that drug is available. When an anaesthetist is learning a new technique, it will take longer to perform than when one is more practised. When one is familiar with the technique, spinal anaesthesia can be very swiftly performed. There is a theoretical risk of introducing infection into the sub-arachnoid space and causing meningitis. This should never happen if equipment is sterilised properly and an aseptic technique is used.