<prompt> The triad of hypertension, bradycardia and irregular respiration is seen in:Cushings reflexBezold-Zarisch reflexHerring-Bruer reflexBainbridges reflex  <response>: Ans. a. Cushings reflex Ref: Ganong 24e p607; Schwartz 9e p1521; Bailey 25e p483The triad of hypertension, bradycardia and irregular respiration is seen in Cushings reflex.Elevated intracranial pressure, as caused by space occupying lesion like brain tumor or head trauma with associated intracranial bleeding e.g. epidural subduralcerebral- haemorrhage, results in an increased systemic blood pressure BP and bradycardiaQ rather than tachycardia and irregular breathing. This response is called Cushings reflex or phenomenon. Cushings TriadIncrease in systolic blood pressureQ Widening of pulse pressureReduction of the heart rateQ bradycardiaIrregular respirationQ caused by impaired brainstem functionCushing ReflexCushing reflex also referred to as the vasopressor response, is a physiological nervous system response to increased intracranial pressure ICP that results in Cushings triad of increased blood pressure, irregular breathing, and a reduction of the heart rateQ.It is usually seen in the terminal stages of acute head injury and may indicate imminent brain herniationQ.These symptoms can be indicative of insufficient blood flow to the brain ischemia as well as compression of arteriolesQ.Etiology:It is a special CNS ischemic response that results from increased intracranial tension or increased CSF pressure around the brain in cranial vault.Causes of increased ICT may be space occupying lesions such as brain tumorQ, cerebral abscess, head traumaQ with associated intra cranial bleeding epidural subdural cerebral-haemorrhagePathophysiology:When the ICT or CSF pressure rises to equal the arterial pressure, it compresses the whole brain as well as the arteries in the brain and cuts off the blood supply to the brain, thereby activating the CNS ischemic responseCompromised blood supply, local hypoxia and hypercapnia of RVLM rostral ventrolateral medulla neurons or vasomotor area increase their discharge and evoke Cushings reaction raising systemic arterial pressureQ.Cushing ReflexThe resultant rise in systemic arterial pressure due to ischemic stimulation of vasomotor regions in medulla tend to restore the blood flow to medulla, thereby protecting the vital centers of brain from loss of nutrition if ICT rises enough to compress cerebral arteries.The rise in BP is proportional to increase in intracranial tension over a considerable range and causes a reflex decrease in heart rate via the arterial baroreceptors. This is why bradycardia rather than tachycardia is characteristically seen in patients with increased intra cranial pressureQ.Bezotd-Jarisch reflex In experimental animals, injections of serotonin, veratridine, capsaicin, phenyldiguanide. and some other drugs into the coronary arteries supplying the left ventricle cause apnea followed by rapid breathing, hypotension, and bradycardia the coronary chemoreflex or Bezold-Jarisch reflex. The receptors are probably C fiber endings, and the afferents are vagal. The response is not produced by injections into the blood supply of the atria or the right ventricle.Hering-Bruer reflex The Hering-Breuer inflation reflex is an increase in the duration of expiration produced by steady lung inflation, and the Hering-Breuer deflation reflex is a decrease in the duration of expiration produced by marked deflation of the lung.Bainbridges reflex Rapid infusion of blood or saline in anesthetized animals sometimes produces a rise in heart rate if the initial heart rate is low. This effect was described by Bainbridge in 1915, and since then it has been known as the Bainbridge reflex. 