What gas is commonly used to fill the balloon in an intra-aortic balloon pump?

The gas commonly used to fill the balloon in an intra-aortic balloon pump is helium. This choice is correct primarily because helium has several advantageous properties that make it ideal for this application. Helium is lighter than other gases, which allows for rapid inflation and deflation of the balloon. This quick response is crucial for the functioning of the intra-aortic balloon pump, as it needs to synchronize with the cardiac cycle to effectively assist in improving myocardial perfusion and reducing left ventricular workload.

Additionally, helium has a low density and low viscosity, which helps in minimizing the resistance to flow, allowing the balloon to meet the demands of inflation and deflation efficiently. The use of helium also reduces the risk of embolism compared to gases that are more soluble in blood, making it a safer choice for patients during cardiac support.

Intra-aortic balloon pumps rely on the timed inflation and deflation of the balloon to assist the heart's pumping ability, and using helium enables this process to occur with minimal delay and maximum effectiveness.