Orthostatic reactions and blood volumes after moderate physical activation during acute febrile infections

Abstract

In 18 patients suffering from viral, mycoplasma or bacterial infections, orthostatic reaction and total haemoglobin were measured after termination of fever and 1 and 3 months thereafter. The results of the 3 months control were considered to represent the individual's normal values. The patients were randomized into two groups, one of which was subjected to a physical activity programme when febrile and the other, serving as control group, was confined to bed according to traditional clinical routine. The orthostatic reaction was measured as the mean heart rate during 10 min tilting on a tilt table. Plasma and red cell volumes were calculated from total haemoglobin, haemoglobin concentration and erythrocyte volume fraction. After fever heart rate during tilt was, in both groups, significantly higher than at the 3 months control but it was lower in the trained group (86 +/- 4 beats/min) than in the control group (100 +/- 3 beats/min) (P less than 0.05). Plasma volume and red cell volume being both numerically reduced in our patients after fever, showed a significant increase 3 months after illness only in the untrained control group. The results suggests that physical activity during acute febrile infections prevents the illness/bed rest-induced orthostatic deterioration and blood volume reduction.