METABOLIC RESPONSE TO TRAUMA
INTRODUCTION
Homeostasis is the co-ordinated physiological process which maintains most of the steady states of the organism. Metabolic response to trauma refers to certain physiological responses activated after trauma which serves for “self preservation” and maintenance of homeostasis; but which may become pathological if uncontrolled or prolonged. Resuscitation, surgical intervention and critical care can return the severely injured patient to a situation in which homeostasis becomes possible once again It is important to recognise that the response to injury is graded and it evolves with time: the more severe the injury, the greater the response. These response components include physiological consequences(increased cardiac output and ventilation,
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ADH, elaborated by the supraoptic and paraventricular nuclei of the hypothalamus and stored in the posterior pituitary, increases the permeability of the collecting ducts with reabsorption of water from the urine leading to antidiuresis. Factor that stimulate its secretion include
• Osmoreceptors that detect increased osmolality of the plasma (above 280 mOsm1L) near the supraoptic and paraventricular nuclei
• Haemorrhage is a very potent stimulator
• Decreased tension of the atrial walls, great veins and pulmonary vessels, as occurs in hypovolaemia, stimulates increased ADH
• Renin-angiotensin mechanism: Angiotensin, released as a result of decreased renal blood volume or pressure, directly stimulates ADH secretion
• Cutaneous and Visceral Pain: Visceral manipulation, pain and emotional stress also stimulate ADH secretion.
• Drugs: Ether, nicotine, morphine and barbiturates can stimulate ADH secretion while alcohol inhibits