Semisitting Position and Venous Air Embolism in Neurosurgical Patients with Patent Foramen Ovale: A Systematic Analysis

The semisitting position (SSP) offers significant advantages for neurosurgeons but presents numerous challenges to anesthesiologists. One major concern is venous air embolism (VAE). The incidence of patent foramen ovale (PFO) is approximately 10-35%. Typically, PFO causes a left-to-right shunt, but there is also a possibility of paradoxical embolism. Patients who undergo sitting craniotomies are routinely evaluated using a preoperative transthoracic echocardiogram (TTE) or transesophageal echocardiogram (TEE). Even in the presence of a PFO, neurosurgeons frequently prefer to perform surgery in the SSP. The incidence of venous air embolism in the sitting position is 23-45%. However, the rate of clinically significant air embolism is significantly lower. We conducted herein a systematic review of the incidence rates of PFO, venous air embolism, and complications in patients undergoing semisitting neurosurgical procedures. According to our analysis, the incidence of VAE was similar in both unknown and known PFO status patients (23.5% vs. 24.5%; p = 0.88) undergoing semisitting neurosurgical procedures. Other complications, such as hypotension, MI, stroke and perioperative deaths, could not be compared between the two groups due to inadequate power. However, there is a lack of level A evidence from currently available observational studies. Definitive evidence-based recommendations and guidelines based on well-designed studies are required to address this problem.