Clinical use of a portable electronic device to measure haematocrit
A small portable device called the blood electrometer (HEM) was developed to assist clinicians to distinguish patients with extreme blood loss from those with normal packed cell volumes. Blood was collected in 5 ml lithium heparin tubes from 80 normal controls and 24 patients in an intensive care unit. BEM and accurate microcentrifugal techniques were compared. Intraclass correlation coefficients between the techniques of r =0,96 and r =0,93 were found in the normal controls and patients respectively. Because the BEM operates on the principle of conductivity, changes in some of the biochemical variables which could influence conductivity were investigated in the patients. Mean plasma total protein and albumin concentrations were lower compared with normal reference ranges. Six of the 24 patients were acidotic and 4 alkalotic. Leucocyte counts obtained randomly from 13 patients were elevated. Changes in measurements which could influence conductivity did not affect the BEM reading. We conclude that the portable BEM could be of great value in circumstances where a fixed power source is not available and rapid haematocrit measurements in a large number of patients are required.