effect of acute heat exposure on the blood components and blood volume in man

ABSTRACT

This experiment was done on eighteen [18] male healthy volunteers; they were exposed to 25 degree and 40 percent relative humidity [R.H.] in an acclimatisation chamber for 60 minutes [control time] preceeded by a period of 80 minutes at 40 degree and 40 percent RH [test time]. The haemoglobin, haematocrite, red blood cells, reticulocyte, platelet, total and differential leucocytic counts were estimated. The individual differences in blood volume and haematocrite between control and test time were also calculated from haemoglobin and haematocrite. The reticulocytic and red cell count remained unchanged denoting no effect of heat stress on erythropoiesis, similarly total and differential leucocytic count showed non-statistical significant change while platelet count were significantly increased. The combined data of haemoglobin and haematocrite revealed no statistical changes though there was great individual variation in blood volume. Haemodilution was evident in 56 percent of cases and 44 percent showed haemoconcentration. As haemodilution occurred in heat tolerant individuals calculation of blood volume might be used as a simple test to differentiate between heat tolerant and heat non-tolerant people