All of us must have suffered from diarrhoea at least once in our lifetime. How do you feel thereafter? Well most of us must have experienced weakness, dizziness, dryness of mouth and anorexia. Our skin also becomes dry and loose. During diarrhoea the stools are loose and have high water content - an indicator that water is being lost in higher than normal amounts. The stools also contain a high amount of: electrolytes due to enhanced peristaltic movements i.e. increased movements of the stomach and inteslines. This results in the deficiency of water and electrolytes in the body which is referred to as dehydration. Dehydration results in reduction in the extracellular blood volume and hence a reduction in the total blood volume which is often referred to as hypovolemia. Low blood volume is associated with hypotension and a low cardiac output. In response to hypotension, the heart tries to compensate by increasing the number of cardiac cycles per minute which is indicated by a high pulse rate. You will often find that during diarrhoea the patients have low blood pressure but usually a higher than normal pulse rate. As the severity of dehydration increases, despite enhanced cardiac? Cycles, adequate amount of blood and nutrients do not reach all body parts/organs. The patient is therefore cold to touch at the extremities. Another complication that may arise if severe dehydration does not receive prompt medical care is ischemic damage to the tissues of various organs due to reduced supply of oxygen and nutrients. Of most significance is damage to the kidneys and brain. Reduced blood volume results in reduced glomerular filtration rate and hence a low urine output. This in turn can 'result in accumulation of toxic waste products in the blood which can be measured by the level of blood urea nitrogen levels. Other associated changes can be observed in the form of azotemia - abnormal high level of urea and creatinine and metabolic acidosis which develop during acute renal failure. Acute renal failure is particularly observed during severe diarrhoea coupled with delayed or absence of adequate fluid management. Another consequence, which we were discussing, involved changes in the nervous system. They can be as mild as dizziness due to less supply of oxygen, glucose and other nutrients to the brain cells or as severe as resulting in coma due to excessive accumulation of nitrogenous waste products and other toxic metabolites in the blood. It would thus be evident that maintenance of adequate blood volume is imperative to prevent dehydration and its consequences some of which call be life threatening.

By now, you must have understood the seriousness of diarrhoea and can understand that it is the highest cause of illness and death especially in children.