Gas embolism: helium is more lethal than carbon dioxide.

The search for alternatives to carbon dioxide (CO2) for insufflation during laparoscopy has included the consideration of helium. Helium is attractive because it is noncombustible and has no pharmacologic effects. Unfortunately, it is also relatively insoluble in blood, which potentially could exacerbate a venous gas embolism. We performed rapid intravenous injections of CO2 and helium into 4 dogs in amounts ranging from 5 to 10 ml of gas per kilogram body weight. Recovery after CO2 injection always occurred within 1 min. In 4 of 6 instances, the helium injection was fatal. Our results confirm that helium is more lethal than CO2 when injected intravenously. This implies that the use of helium for insufflation during laparoscopy might place patients at greater risk for adverse effects should venous gas embolism occur.