Cushing’s Triad

What Is It, Causes, Assessment Findings, Treatment, and More

Author: Ashley Mauldin, MSN, APRN, FNP-BC

Editors: Ahaana Singh, Ian Mannarino, MD, MBA

Illustrator: Aileen Lin

What is Cushing’s triad?

Cushing’s triad refers to a set of signs that are indicative of increased intracranial pressure (ICP), or increased pressure in the brain. Cushing’s triad consists of bradycardia (also known as a low heart rate), irregular respirations, and a widened pulse pressure. A widened pulse pressure occurs when there is a large difference between the systolic blood pressure (the blood pressure when the heart is contracting) and the diastolic blood pressure (the blood pressure when the heart is relaxing). Cushing’s triad is indicative of a medical emergency and medical attention is required. 

What causes Cushing’s triad?

• Increased ICP results in a lack of oxygen in brain tissue and a restriction of cerebral blood flow in the brain. 

  • This is most commonly caused by a head injury, bleeding in the brain (i.e. hematoma or hemorrhage), tumor, infection, stroke, excess cerebrospinal fluid, or swelling of the brain. 

• Increased ICP activates the Cushing reflex, a nervous system response resulting in Cushing’s triad. 

  • As the ICP begins to increase, it eventually becomes greater than the mean arterial pressure, which typically must be greater than the ICP in order for the brain tissue to be adequately oxygenated. 

    • The difference in pressure causes a decrease in the cerebral perfusion pressure (CPP), or the amount of blood and oxygen the brain is receiving, therefore leading to the brain not receiving enough oxygen (also known as a brain ischemia). 

      • To compensate for the lack of oxygen, the sympathetic nervous system is activated, causing an increase in systemic blood pressure and an initial increase in heart rate. 

        • The increased blood pressure then signals the carotid and aortic baroreceptors to activate the parasympathetic nervous system, causing the heart rate to decrease. 

  • As the pressure in the brain continues to rise, the brain stem may start to dysfunction, resulting in irregular respirations followed by periods where breathing ceases completely. This progression is indicative of a worsening prognosis. 

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What are the signs and symptoms of Cushing's triad?

• Widened pulse pressure

• Bradycardia 

• Irregular respirations (also known as Cheyne–Stokes respirations) 

  • Cheyne-Stokes respirations consist of periods of slow, deep breaths followed by periods of apnea, when breathing comes to a complete stop. 

• Hypertension, or increased blood pressure 

• Additional symptoms 

  • Headaches

  • Vomiting

  • Blurred vision

  • Weakness

  • Changes in behavior or level of consciousness

What are the assessment findings of Cushing’s triad?

• Procedural diagnosis is necessary to definitively diagnose Cushing’s triad by measuring ICP.

  • Lumbar puncture (spinal tap) in which the cerebrospinal fluid is measured.

  • Continuous monitoring by a catheter placed in the ventricle of the brain. 

• Clinical evaluation can be performed to help determine the underlying cause.

  • Medical history review

  • Physical examination 

• Imaging may be required to determine the underlying cause.

  • CT scans 

  • MRI

How do you treat Cushing’s triad?

Treatment is aimed at decreasing the ICP, as well as reversing the cause of the increased intracranial pressure. Prescribed treatment is often individualized and will depend on the severity of the symptoms. 

• Medications

  • Mannitol (osmotic diuretic medication) is often provided intravenously and can be highly effective in lowering ICP and increasing cerebral perfusion pressure (CPP). 

  • Other medications often used in combination with mannitol:

    • Diuretics (e.g. furosemide)

    • Steroids (e.g. methylprednisolone)

    • Sedatives (e.g. propofol) 

• Hyperventilation, or breathing very fast, is recommended to help lower ICP. 

• Laying in the reverse Trendelenburg position (with the head elevated) 

• Drainage of the extra cerebrospinal fluid may be required to decrease the pressure. 

• Rarely, a craniotomy, or removal of a small portion of the skull, may be performed to alleviate the rising pressure. 

If Cushing's triad is left untreated for too long, 

• Herniation can occur, causing the brain tissue to shift to the opposite side of the brain or down towards the brainstem (uncal herniation). 

  • Uncal herniation can lead to various symptoms, including loss of certain reflexes, loss of consciousness, and potentially death. 

• Infarction, or death of the brain tissue, can occur. 

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