Pulmonary oedema, larygospasm and arterial gas embolisms?

[bleeb]

There's been increased recognition of the phenomenon of Immersion Pulmonary Edema (IPE) in divers in recent years, some of which is a results of people posting their unpleasant experiences here on ScubaBoard. From some of what's been published lately, I gather there are some similarities and some differences from PE in swimmers, apparently most frequently in highly fit people swimming in triathalons. With all the jostling, thrashing around and waves of a triathalon swim, breathing in water might be slightly more likely, with the accompanying increased chance in larygospasm. In these highly fit individuals who may already be working hard, could they then be sucking hard enough to cause a pulmonary edema? Is this one area researchers are looking at?

And where this works back to diving: If a diver suffered a larygospasm and popped some alveoli, is there an gas embolism component when someone suffers IPE?

 

[Duke Dive Medicine]

There's been increased recognition of the phenomenon of Immersion Pulmonary Edema (IPE) in divers in recent years, some of which is a results of people posting their unpleasant experiences here on ScubaBoard. From some of what's been published lately, I gather there are some similarities and some differences from PE in swimmers, apparently most frequently in highly fit people swimming in triathalons. With all the jostling, thrashing around and waves of a triathalon swim, breathing in water might be slightly more likely, with the accompanying increased chance in larygospasm. In these highly fit individuals who may already be working hard, could they then be sucking hard enough to cause a pulmonary edema? Is this one area researchers are looking at?

One important thing that you touched on is that IPE is a coat of many colors, so to speak. In a triathlete, it's probably related to higher-than-normal cardiac output coupled with a blunted response of the pulmonary vasculature when the athlete is immersed. In others, including divers, there could be a cardiac component, e.g. heart failure that is either subclinical or asymptomatic on the surface, but becomes problematic with immersion and increased exercise.

Re laryngospasm: the phenomenon you're describing is negative pressure pulmonary edema. It's been documented in postoperative patients who suffer from laryngospasm after removal of the breathing tube and is a possible culprit in some diving accidents, one of which has been extensively covered here. I don't think it's a factor in triathletes with IPE because we can demonstrate significantly elevated pulmonary artery pressures in susceptible athletes simply by immersing them in cold water. Also, most triathletes who we've seen who suffer from IPE have had multiple incidents and have not described water aspiration.

And where this works back to diving: If a diver suffered a larygospasm and popped some alveoli, is there an gas embolism component when someone suffers IPE?

A diver wouldn't need to have IPE in order to suffer an AGE if a laryngospasm occurred under water. A diver could aspirate water through, say, a torn regulator diaphragm... this could lead to laryngospasm, panic, and rapid ascent. Pulmonary edema wouldn't need to be a factor.

 

[Saturation]

Laryngospasm from inhaling water, or worse cold water, only affects the larynx and maybe pharynx, not the trachea or lungs. In cases I've witnessed or been personally involved, all healthy divers, it resolves in seconds, so staying calm and waiting is key. If the diver panics and attempts to surface and can't exhale, barotrauma of all sorts can occur, but it won't be IPE.

IPE occurs in the lung parenchyma, as a filling with fluid and does not involve the upper airways.