Colleagues,

Could anyone help with the physiology –

From the history provided by others: 50 year old gentleman with longstanding exertional pains in his muscles of uncertain aetiology, felt increasingly tired, lightheaded with tingling in his arms and legs. He was sweaty and felt he was going to pass out.

On admission to A+E,  his blood gases showed pH 7.59, pCO2 2.25, pO2 17.4, Bic 16.1 mmol/l, BE -3 with lactate 6.1 mmol/l. This was repeated at  6.5 mmol/l. (K 4, adj Ca 2.12, creat 87, normal LFTs)

I assume he has a partially compensated acute respiratory alkalosis. From the Oxford Textbook, the suggestion is that alkalosis has an effect on phosphofructokinase stimulating glycolysis. The more pyruvate formed the more lactate. Given that alkalosis, will stop NH3 release and stimulate bicarbonate loss, the effect will be to inhibit lactate renal excretion. The Oxford textbook suggests that mild increase in lactate would occur unless there was liver dysfunction – not evident in above case.

Tietz (3^rd edition) suggests that with chronic respiratory alkalosis, lactate may increase to 2-4 mmol/l from enhanced glycolysis and lactate with levels probably ‘owning to a decrease in hepatic blood flow’.

At review his lactate was 0.8 mmol/l. Repeat Gases weren’t undertaken or a bicarbonate requested.

Is anyone willing to speculate whether the lactate could rise to 6.5 mmol/l in someone with normal BPand pulse during this scenario?

Thank you for your help

Peter Galloway

Glasgow