What could cause a sudden decrease in ETCO2 from 35 to 0 during a total hip replacement procedure?

A sudden decrease in end-tidal carbon dioxide (ETCO2) levels from 35 to 0 during a total hip replacement procedure can indeed be attributed to venous air emboli. When air enters the venous system, it can lead to a range of physiological changes. In particular, bubbles can obstruct blood flow, preventing the delivery of carbon dioxide to the lungs, which is where it is normally expelled from the body. This results in a dramatic drop in ETCO2 readings, indicating that carbon dioxide is not being effectively removed from the bloodstream.

In surgical contexts, especially those involving manipulation of large blood vessels or cavities, the risk of air entering the venous system can increase, leading to this serious complication. This sudden change in ETCO2 often prompts immediate investigation to address the underlying cause and ensure patient safety.

Other factors, such as hypothermia, tourniquet release, or circuit disconnects, while they may cause various changes in physiology or capnography readings, do not typically lead to an immediate and complete cessation of ETCO2. These factors could cause reduced ETCO2 readings but would not typically bring the level down to zero as seen with significant air embolism. Understanding the implications of venous air emboli is