From the Guidelines
Cushing reflex is a life-threatening medical emergency characterized by a triad of hypertension, bradycardia, and irregular breathing patterns, occurring in response to increased intracranial pressure, as noted in the 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay 1.
Definition and Pathophysiology
Cushing reflex is a physiological response to increased intracranial pressure, which can be caused by various conditions such as brain injury, hemorrhage, tumor, or other disorders affecting the brain. This reflex is a protective mechanism aimed at maintaining cerebral perfusion when the brain is under pressure. The body attempts to preserve blood flow by increasing systemic blood pressure, which is accompanied by a slowing heart rate due to baroreceptor activation.
Clinical Presentation and Management
The clinical presentation of Cushing reflex includes a triad of symptoms: hypertension, bradycardia, and irregular breathing patterns. Recognition of this reflex is crucial in neurological assessment as it often precedes brain herniation and can be life-threatening if not promptly addressed. Management of Cushing reflex involves reducing intracranial pressure through measures such as elevation of the head, hyperventilation, osmotic diuretics like mannitol, or surgical decompression.
Key Considerations
- Cushing reflex is a late sign of increased intracranial pressure and indicates compression of the brainstem, specifically the medulla oblongata.
- The reflex is a medical emergency requiring immediate intervention to reduce intracranial pressure.
- Prompt recognition and management of Cushing reflex are critical to prevent life-threatening complications such as brain herniation.
- The 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay provides recommendations for the management of bradycardia in the setting of neurologic disorders, including Cushing reflex 1.
From the Research
Definition of Cushing Reflex
- Cushing reflex, also known as Cushing's reflex or Cushing's response, is a physiological nervous system response to increased intracranial pressure (ICP) that results in Cushing's triad 2.
- The triad consists of three primary signs: increased blood pressure, irregular breathing, and a reduction in heart rate (bradycardia) 2.
Causes and Triggers
- The Cushing reflex can be triggered by various factors, including traumatic brain injury, intracranial hemorrhage, and other conditions that lead to increased ICP 3.
- Acute elevations in intra-abdominal pressure, such as those occurring during abdominal compartment syndrome, can also lead to increased ICP and trigger the Cushing reflex 2.
Clinical Significance
- The Cushing reflex is a critical response to increased ICP, as it helps to maintain cerebral perfusion pressure and prevent further brain damage 3.
- However, the reflex can also have negative consequences, such as decreased urine output and increased serum vasopressin levels, which can exacerbate the condition 2.
Treatment and Management
- Treatment of increased ICP and the Cushing reflex typically involves a multimodal approach, including medical and surgical interventions 4, 3.
- Medical options may include the use of hypertonic saline, mannitol, and other hyperosmolar therapies to reduce ICP, as well as measures to control blood pressure and ensure adequate cerebral perfusion 4, 5.
- Surgical options may include CSF drainage, decompression of surgical lesions, and other procedures to reduce ICP and alleviate the underlying cause of the Cushing reflex 3.