Transient ischemic attacks from arterial gas embolism induced by glossopharyngeal insufflation and a possible method to identify individuals at risk
Breath-hold divers report transient, severe neurological symptoms that could be caused by arterial gas embolism after glossopharyngeal insufflation. This technique is often used to overinflate the lungs and stretch the chest prior to breath-holding and can increase the transpulmonary pressure to around 7–8 kPa, so introducing risk of pulmonary barotrauma. Airway pressure, blood pressure and static spirometry (nitrogen dilution) were measured simultaneously in ten subjects attempting to identify individuals at risk. Compared to baseline, total lung capacity (TLC) after glossopharyngeal insufflation increased by 19 % along with increased vital capacity (23 %) and residual volume (6 %) (P < 0.05), while mean relaxed airway pressure (P aw) at TLC increased from 3.62 ± 0.93 to 7.26 ± 2.04 kPa as a result of performing glossopharyngeal insufflation (P = 0.0001). Blood pressure fell during glossopharyngeal insufflation and attained relaxed airway pressure correlated positively to baseline mean arterial pressure in the subjects. Two of the subjects had glossopharyngeal insufflation-related accidents before the study and two subjects (with the highest P aw during GI; 9 and 10.3 kPa respectively) suffered glossopharyngeal insufflation-related accidents within 6 months after our study, with one suffering a non-fatal drowning accident. The principal finding of this study was that some subjects were able to use GI to reach P aw high enough to suggest a risk of pulmonary barotrauma, while other subjects would lose consciousness due to hypotension while still within safe limits of pulmonary pressure. This mechanism could offer an alternative explanation to drowning in breath-hold divers, and indicates that glossopharyngeal insufflation should be avoided or done with extreme caution.