Dyspnea on immersion: mechanisms in patients with bilateral diaphragm paralysis

Patients with bilateral diaphragm paralysis are able to inflate their lungs by two mechanisms: relaxing the abdominal wall or expanding the rib cage. Each maneuver promotes lung expansion by shifting support of the abdominal contents from the abdominal wall to the diaphragm. We describe a patient with bilateral diaphragm paralysis who experienced acute dyspnea when immersed in water to the level of the abdomen and discuss the precipitation of dyspnea in the context of the strategies available to these patients for lung inflation.