Monday April 6, 2009

Q; What amount of air is usually needed to cause clinical symptoms in Venous Air Emboilsm (VAE)?

Answer: Around 50 ml

Most occurrences of VAE go unreported because they are asymptomatic due to very small amount of air entering system, but entrapment of large quantities of intravascular gas may lead to severe neurologic injury, cardiovascular collapse, or even death. The factors that determine the subsequent morbidity and mortality include the rate of air entrainment, the volume of air introduced, and the position of the patient at the time of the embolism. Although very small volumes of air can lead to severe sequelae, generally it is accepted that atleast 50 mL of air is required to cause clinical symptoms.

But again, all precautions should be taken to avoid even any small amount of air to get introduce into vascular system as there are case reports in literature showing lethal effect with as little as 20 mL of air (the length of an unprimed IV infusion set) or even 0.5 mL of air in the left anterior descending coronary artery causing ventricular fibrillation.

Related previous pearl: Venous Air Embolism - VAE - immediate maneuvers

Reference:

Venous Air Embolism - emedicine.com