B. Nagarjuna, G. Prabhakar Siva
BACKGROUND Disorders of acid-base homeostasis complicate a variety of disease conditions and contribute to morbidity and mortality. Unless promptly recognised, these disorders disrupt normal functioning of various organ systems and ultimately prove fatal. The clinical settings in which such acid-base disorders occur are numerous that attempting to list out all the causes of acid-base disturbances will be exhaustive and unwarranted. Nevertheless, to make some generalisation, it can be said, diseases of the lungs and kidneys (the two important organs involved in acid-base homeostasis) contribute to an important proportion of such acid-base disturbances. MATERIALS AND METHODS In all patients, preliminary history regarding duration of diarrhoea, presence of vomiting and oliguria was recorded. Clinical examination was focussed on identifying the degree of dehydration, acidotic breathing if any, vital signs and systemic examination to rule out coexisting diseases that might confound the acid-base picture. In all patients, routine urinalysis for albumin, sugar and deposits was done. Also, urine was analysed for acetone, since patients with diarrhoea could starve resulting in starvation ketoacidosis. In all patients, haemoglobin estimation was routinely done. It is mandatory to know the haemoglobin level for determining oxygen content of blood in ABG analysis. If any patient was found to have renal failure (defined as serum creatinine >2 mg%). Serial measurements were made as appropriate and after treatment. RESULTS 14 out of 52 patients with acute diarrhoea had ARF. All 14 patients had increased anion gap metabolic acidosis. 7 out of 52 patients with acute diarrhoea had severe metabolic acidosis (pH <7.2). Out of these 7 patients, 5 had renal failure and 2 patients had normal renal parameters. CONCLUSION The most common acid-base disturbance observed in patients with acute diarrhoeal disease is normal anion gap metabolic acidosis. Other acid-base patterns observed include increased anion gap metabolic acidosis and a normal ABG study. A normal ABG must be interpreted in the clinical context because mixed acid-base disorders may produce normal values in ABG analysis. The acid-base abnormality observed in post diarrhoeal ARF is increased anion gap metabolic acidosis. Metabolic acidosis is a prognostic factor and early recognition and prompt correction of metabolic acidosis improves the outcome in acute diarrhoeal disease and post diarrhoeal ARF.
