| Metabolic
acidosis (predominantly lactic acidosis) has been now recognized as a principal
pathophysiological feature of severe manifestations of P. falciparum
malaria like cerebral
malaria and severe anemia. It is the single most important determinant of survival and can
lead to respiratory distress syndrome. Lactic acidosis has been identified as an important
cause of death in severe malaria. Lactic
acidosis in severe malaria has been attributed to several causes:
- Increased production of lactic acid by
parasites (through direct stimulation by cytokines)
- Decreased clearance by the liver
- Most importantly the combined effects of
several factors that reduce oxygen delivery to tissues
- Marked reductions in the deformability of
uninfected RBCs may compromise blood flow through tissues
- Dehydrated and hypovolemia can exacerbates
microvascular obstruction by reducing perfusion pressure
- Destruction of RBCs
and anemia further
compromises oxygen delivery.
Mean venous blood lactate concentrations
have been found to be almost twice as high in fatal cases as in survivors and to correlate
with levels of tumour necrosis factor and interleukin 1-alpha. The lactate concentrations
fell rapidly in survivors but fell only slightly, or rose, in fatal cases. Sustained
hyperlactataemia has been found to be the best overall prognostic indicator of outcome.
Management:
- Maintenance of airway patency and oxygen
delivery; intubate if the patient is unconscious, in severe shock, or otherwise unstable
- Establish an intravenous (IV) line;
replace adequate intravascular fluid volume if the patient has tachycardia, hypotension,
or other signs of poor tissue perfusion like poor capillary refill.
- Monitor for cardiac dysrhythmias.
- The use of sodium bicarbonate is
controversial and generally should be avoided
References:
- Miller LH, Baruch DI, Marsh K et al. The
pathogenic basis of malaria. Nature 2002;415:673-9
- Krishna S, Waller DW, ter Kuile F et al.
Lactic acidosis and hypoglycaemia in children with severe malaria: pathophysiological and
prognostic significance. Trans R Soc Trop Med Hyg. 1994 Jan-Feb;88(1):67-73.
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