In head trauma patient, why there is bradycardia + increase blood pressure?
CUSHING REFLEX
The Cushing reflex is a hypothalamic response to ischemia, usually due to poor perfusion (delivery of blood) in the brain.
The Cushing reflex consists of an increase in sympathetic outflow to the heart as an attempt to increase arterial blood pressure and total peripheral resistance, accompanied by bradycardia.
The ischemia activates the sympathetic nervous system, causing an increase in the heart's output by increasing heart rate and contractility along with peripheral constriction of the blood vessels. This accounts for the rise in blood pressure, ensuring blood delivery to the brain. The increased blood pressure also stimulates the baroreceptors (pressure sensitive receptors) in the carotids, leading to an activation of the parasympathetic nervous system, which slows down the heart rate, causing the bradycardia.
The Cushing reflex is usually seen in the terminal stages of acute head injury.
The Cushing reflex was first described by Harvey Cushing in 1902.
source : http://signsandsyndromes.com/cushing-reflex
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CUSHING TRIAD
Cushing's triad is a sign of increased intracranial pressure.
It is the triad of :
1. Hypertension (progressively increasing systolic blood pressure)
2. Bradycardia
3. Widening pulse pressure (an increase in the difference between systolic and diastolic pressure over time)
Cushing's triad suggests a cerebral hemorrhage in the setting of trauma or an space occupying lesion (e.g. brain tumor) that is growing and a possible impending fatal herniation of the brain.
Cushing's triad is named after an American neurosurgeon Harvey Williams Cushing (1869-1939).
source : http://classictriads.com/triads/cushings-triad
Thanks to Dr Johar (A&E) for asking us these questions
Learning issue : Differentiate between Cushing's disease and cushing's syndrome?
A115262
7 comments:
just some additional info,
the cerebral ischemia cause decrease in pH and increase in pCO2. the central chemoreceptor sense it and activate the sympathetic nervous system.
and,
the increase in ICP which impinge on the vagal nerve can mechanically stimulate the parasympathetic nervous system and cause bradycardia as well.
oh ya, one more thing.. from the info i found,
cushing triad is
-bradycardia,
-hypertension (with widened pulse pressure), and
-irregular/a change in respiratory pattern
herniation/high pressure on brainstem causes the irregular respiratory pattern.
source: http://www.emedmag.com/html/pre/cov/covers/121501.asp
So, basically Cushing's Triad mesti ada bradycardia and hypertension la ? Yang 3rd point tu which one is correct ? >.<
I guess Cushing Reflex cause Cushing's Triad right ?
Irregular breathing pattern a/w apneoa
See this:
http://egnahcaes.wordpress.com/2012/01/07/difference-between-cushings-sign-and-cushings-reflex/
:)
what is the relation cushing reflex . and cushing disease
cushings disease is a long term illness with too much cortisol being produced. Moon shaped face, male facial pattern hair growth, anxiety, hyperhydrosis. Cushings reflex is due to actue head trauma. BP up, HR down, and irreg. resp. patterns known as cheyen stokes. It is usually terminal. herniation at brainstem causes the irreg. resp. pattern ....from your hometown paramedic :)
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