Definition
The Cushing reflex classically presents as an increase in systolic and pulse pressure, reduction of the heart rate (bradycardia), and irregular respiration. It is caused by increased pressure inside the skull. These symptoms can be indicative of insufficient blood flow to the brain (ischemia) as well as compression of arterioles.
In response to rising intracranial pressure (ICP), respiratory rate increases. The increase in ventilation is exhibited as an increase in rate rather than depth of ventilation, so the Cushing reflex is often associated with slow, irregular breathing. Mayer waves, which are waves in arterial blood pressure that can be seen in an electrocardiograph (ECG) register or blood pressure traces, are a symptom of a physiological response to falling blood flow. This often results in an increase in blood pressure.
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