A streamlined protocol for the use of the semi-sitting position in neurosurgery: a report on 48 consecutive procedures.

The semi-sitting position has lost favor among neurosurgeons partly due to unproven assumptions of increased complications. Many complications have been associated with this position; the most feared: venous air embolism and paradoxical air embolism. We report on this retrospective study of the outcome over 4 years of 48 neurosurgical patients operated on consecutively using a standardized protocol: 41 (85%) in the semi-sitting position, and seven (15%) in the prone position. Procedures included: tumor resection (34), posterior fossa decompression (12), cyst resection (1) and resection of arteriovenous malformation (1). Pre-operative workup was standardized. Vigilant intra-operative observation was done by an experienced neuroanesthetist. Pertinent data was extracted from surgical records. Of the 48 patients, 10 (20.8%) were found to have a patent foramen ovale (PFO) on trans-esophageal echocardiography. Of these, four (40%) patients underwent procedures in the semi-sitting position while six (60%) did not. A clinically significant venous air embolism (VAE) was detected during 2 of the 41 semi-sitting procedures (4.9%). Neither patient suffered any obvious sequelae. No other morbidity was encountered associated with surgical position. Our study suggests that a model similar to ours is effective in preventing major complications associated with the semi-sitting position. The semi-sitting position is a safe, practical position that should be considered in appropriate cases. The fear of dreadful complications seems unwarranted.