The dangers of rebreathing: Fluid study showing pooling of exhaled gases.

Infant breathing model while in prone position (facedown). From Itzhak & Greenblatt (2019).

This photograph of an experimental model infant demonstrates the plume cloud of exhaled gases but in liquid form. It is obvious to see how this could be problematic because of rebreathing. In our paper, Dr. Eisenhut and I raise how rebreathing contributes to lowered oxygen and raised carbon dioxide levels in blood as well as increased acid content (acidosis). All of these impact skeletal muscles like the diaphragm causing contractile dysfunction, delayed relaxation followed by increased muscle tone (hypertonicity) and vulnerability to developing diaphragm spasms, flutter and cramps (prolonged spasms). The latter is proposed to cause sudden silent respiratory arrests in infants leading to secondary cardiac arrest and death. The process is very rapid, taking under 10 minutes in total, and is consistent with SIDS and many other sudden unexpected deaths in all ages.

Rebreathing is just one of many factors that contribute to cumulative escalating diaphragm fatigue. Infants are most vulnerable because their respiratory muscles are immature and prone to work overload.

With thanks to Drs. Itzhak and Greenblatt. Their paper can be found here.