Diagnosis and management of metabolic alkalosis.

Elevated pH and elevated plasma bicarbonate level above normal characterise metabolic alkalosis. When bicarbonate is elevated pCO2 must also be elevated to maintain pH to its normal range. Therefore with metabolic alkalosis, the compensation is to decrease alveolar ventilation, and increase pCO2. The causes of metabolic alkalosis are gastro-intestinal hydrogen and chloride loss and due to renal cause. For metabolic alkalosis to continue both generation and maintenance of high levels of bicarbonate are necessary. The diagnosis of metabolic alkalosis is established by noting pH, serum bicarbonate (elevated) and pCO2 (compensatory) elevation. To establish the causes it is necessary to determine intravascular volume, supine and standing blood pressure and renin angiotension alolosterone axis. In chloride responsive alkalosis in which the conditions are extracellular volume depletion, hypokalaemia and hypochloraemia correction of intravascular volume with sodium chloride is needed. In severe metabolic alkalosis of any cause dilute hydrochloric acid (0.1 N HCl) may be infused intravenously but haemolysis may be a complication. In emergency situation with severe hypokalaemia dialysis with higher K+, Cl- and low HCO3- bath will be appropriate.

Role of human leucocyte antigens matching in renal transplantation.

Matching human leucocyte antigens between donors and recipients of solid organ transplantation is essential for short and long term graft survival. Some physicians believe that human leucocyte antigens matching is not essential in renal transplantation. The beneficial effects of human leucocyte antigens-B antigen matching are seen if graft is functioning at least 2 years or more and benefits of human leucocyte antigens-A antigen matching seen if graft is functioning at least for 3 years or more. The one year graft survival rate in first transplant (UNOS registry, USA) being 95% in human leucocyte antigens identical donor, 91% in one haplomatched living related donor and 81% in cadaver related donor. Due to poor techniques to identify the antigens, even six antigen-matched kidneys are rejected. The other reasons with six antigens matching being immunological reaction to non-human leucocyte antigens and non-immunological factors. Kidneys from unrelated donor like spouse with 5 or 6 antigen mismatch (0 to 1 antigen match only) have graft survival approximately equivalent to three-antigen match (haplomatch) family donor. With ischaemia, there is up regulation of antigens on the endothelial surface and predispose to post-transplant rejection. The beneficial effect of maternal graft survival over paternal graft survival suggests prior antigen exposure similar to blood transfusion may help to develop some degree of tolerance.