Introduction: The intraoperative positioning of patients harbouring a posterior fossa lesion is still controversial. In particular, the semisitting position has progressively been abandoned in many centres, mainly due to the perception of an increased risk of complications related to the positioning, such as air embolism, arterial hypotension or peripheral nerve damage. The aim of this study was to determine the incidence of neurological and anaesthetic complications directly associated to the semi-sitting position in an high-volume centre.
Methods: A retrospective cohort analysis of patients undergoing posterior fossa surgery in the semi-sitting position was performed.
Results: From January 2009 to December 2011, 410 operations in the semi-sitting position were performed. All patients were investigated pre-operatively to detect PFO.
During surgery, venous air embolism (VAE) was detected in 74 patients (18%). In 53 cases (71%) VAE was associated to respiratory changes (a drop in ETCO2 =5 mmHg or an O2Sat drop below 90%) or hemodynamic changes (a drop in SysBP=20 points), which were resolved in the course of the operation. Median and mean length of stay were, respectively, 6 and 9.16 days (sd= 11.27) in patients without intra-operative VAE and 6 days and 11.22 days (sd= 15.93) in patients with VAE during surgery (p= 0.16).
There were no surgical complications directly related to the semisitting position, such as acute subdural haematoma secondary to tension hydrocephalus, peripheral nerve damage or quadriplegia secondary to brainstem or spinal cord hypotensive ischemia. Overall, 13 patients required a surgical cavity haematoma evacuation and 17 patients required a shunt for an acute or subacute hydrocephalus; respectively these accounted for 3.17% and 4.14% of our cases.
Conclusions: In a high-volume centre, the semi-sitting positions is a safe and effective choice for posterior fossa and cervical spine surgery. Major complications rates are low and the mean post-operative length of staying is unaffected by the position itself.
Patient Care: We believe that, in a trained high-volume center, the semi-sitting position is a valuable choice for posterior fossa surgery and, in our opinion, it provides several advantages, which could lead to better surgical results.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the pre-operative investigations and the intraoperative monitoring for the semi-sitting position 2) know the main complications possibly related to the semi-sitting position and how to prevent them 3)Discuss the actual risks and the advantages of the semisitting position for posterior fossa surgery 4) consider the semisitting position as a valuable choice when approaching the posterior fossa.