Podcast 871: Increased Intracranial Pressure and the Cushing Reflex

Contributor: Travis Barlock MD

Education Pearls:

• The Cushing Reflex is a physiologic response to elevated intracranial pressure (ICP)

• Cushing's Triad: widened pulse pressure (systolic hypertension), bradycardia, and irregular respirations

• Increased ICP results from systolic hypertension, which causes a parasympathetic reflex to drop heart rate, leading to Cushing's Triad. 

• The Cushing Reflex is a sign of herniation

• Treatment includes:

• Hypertonic saline is comparable to mannitol and preferable in patients with hypovolemia or hyponatremia

• Give 250-500mL of 3%NaCl

• 20% Mannitol - given at a dose of 0.5-1 g/kg

• Each additional dose of 0.1 g/kg reduces ICP by 1 mm Hg

• 23.4% hypertonic saline is more often given in the neuro ICU

• 8.4% Sodium bicarbonate lowers ICP for 6 hours without causing metabolic acidosis

• Non-pharmacological interventions:

• Raise the head of the bed to 30-45 degrees

• Remove the c-collar to improve blood flow to the head

• Hyperventilation induces hypocapnia, which will vasoconsrict the cerebral arterioles

• You hyperventilate on the way to the OR. Otherwise, maintain normocapnia.

References

1. Alnemari AM, Krafcik BM, Mansour TR, Gaudin D. A Comparison of Pharmacologic Therapeutic Agents Used for the Reduction of Intracranial Pressure After Traumatic Brain Injury. World Neurosurg. 2017;106:509-528. doi:10.1016/j.wneu.2017.07.009

2. Bourdeaux C, Brown J. Sodium bicarbonate lowers intracranial pressure after traumatic brain injury. Neurocrit Care. 2010;13(1):24-28. doi:10.1007/s12028-010-9368-8

3. Dinallo S, Waseem M. Cushing Reflex. [Updated 2023 Mar 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK549801/

4. Godoy DA, Seifi A, Garza D, Lubillo-Montenegro S, Murillo-Cabezas F. Hyperventilation therapy for control of posttraumatic intracranial hypertension. Front Neurol. 2017;8(JUL):1-13. doi:10.3389/fneur.2017.00250

Summarized by Jorge Chalit, OMSII | Edited by Meg Joyce & Jorge Chalit, OMSII