Simultaneous Monitoring of Brain and Skin Oxygenation During Haemorrhagic Shock in Piglets

Abstract

Phosphorescence quenching and visible lightguide spectrophotometry were used to measure brain cortex oxygen partial pressure and skin oxygen saturation, respectively, during stepwise haemorrhage and re-transfusion in four 4–7-day-old anaesthetised piglets. In three cases, the effect of administration of adrenalin (epinephrine) was investigated. Brain cortex partial pressure was measured using a conventional phosphorescence pO₂ probe (bc_locpO₂) and using a self-contained phosphorescence microsensor (bc_micropO₂). Peripheral tissue oxygen saturation was measured on the skin of the abdomen (abS_sO₂) and the distal right foreleg (flS_sO₂) using visible lightguide spectrophotometry. Haemorrhage of 65 ml reduced mean arterial blood pressure (MABP) from 75.5 ± 11.0 mmHg (mean ± standard deviation) to 42 ± 2.6 mmHg. Mean bc_locpO₂ fell from 30.1 ± 3.1 to 13.1 ± 2.5 mmHg and mean bc_micropO₂ fell from 33.8 ± 11.4 to 13.3 ± 9.5 mmHg. abS_sO₂ and flS_sO₂ values fell from 47.4 ± 8.1 % and 43.6 ± 10.9 %, respectively, to 21.9 ± 5.5 % and 23.8 ± 14.0 %. Infusion of adrenalin produced a mean transient increase in MABP to 137 ± 2.6 mmHg, falling to 75.7 ± 16.3 mmHg within 3 min. bc_locpO₂ also increased to 24.1 ± 14.6 mmHg, but there were no significant changes in bc_micropO, abS_sO₂ or flS_sO₂. Following reinfusion all parameters returned to values that were not statistically different from their pre-haemorrhage values. The dynamic recordings of all the oxygenation parameters indicated that they were sensitive indicators of the degree of haemorrhage during the experiments.