A Patient with increased BP and decreased hea rate is likely to have

Cushing's reflex , is a physiological nervous system response to increased intra cranial pressure.Results in cushings triad - increased BP, irregular breathing and bradycardia. Usually seen in terminal stages of head injury . It can also be seen after iv administration of epinephrine. In head injury- CPP=MAP-ICP. CPP- cerebral perfusion pressure. MAP- Mean aerial pressure. ICP- intra cranial pressure Head injury causes increased ICP thus lowering CPP causing ischemia. When ICP approaches the level of mean systemic pressure , cerebral perfusion falls . Bodys response to fall in cerebral perfusion is raise systemic blood pressure and dialate cerebral vessels which increases cerebral blood volume and increases ICP followed by lowering CPP.And causes a vicious cycle. When aerial pressure lowers , a reflex called CNS ischaemic response is initiated by the hypothalamus . Hypothalamus activates sympathetic nervous system causing peripheral vasoconstriction and increased cardiac output. This increases aerial pressure and cerebral blood flow is restored. This response stimulates the baroreceptors in the carotid bodies thus slowing the hea rate drastically- bradycardia(baroreceptor reflex -refer image) 2) Marey's law- Explained by barereceptor reflex States that' hea rate is inversely propoional to blood pressue '(but not the vice versa) . Bainbridge reflex- infusion of saline or blood --- increased venous filling of atria--- stimulation of tachycardia producing atrial receptor(TPAR)---tachycardia