Incomplete Cushing's reflex in extracorporeal membrane oxygenation

Area of Science:

• Neurology
• Cardiology
• Critical Care Medicine

Background:

• Cushing's triad (hypertension, bradycardia, irregular respiration) is a classic sign of increased intracranial pressure.
• Extracorporeal membrane oxygenation (ECMO) is a life-support measure used in critical cardiorespiratory failure.
• HeartMate-II is a left ventricular assist device often used as a bridge to transplant.

Observation:

• A patient on veno-arterial ECMO for right ventricular failure developed sudden bradycardia.
• The patient was comatose with no changes in blood pressure or respiration.
• Brain imaging revealed uncal herniation due to diffuse cerebral edema.

Findings:

• Bradycardia was the only presenting sign of Cushing's triad in this ECMO patient.
• Intracranial hypertension manifested solely as bradycardia, without other typical Cushing's triad components.
• This suggests that ECMO can alter the presentation of intracranial hypertension.

Implications:

• Clinicians should consider intracranial hypertension in comatose patients with unexplained bradycardia, especially those on ECMO.
• The sole presence of bradycardia may indicate severe intracranial pressure in patients with advanced circulatory support.
• This case underscores the need for vigilant neurological monitoring in critically ill patients on ECMO.