Injury abolishes the spontaneous haemodynamic recovery from simple haemorrhage

Abstract

Blunt trauma can be regarded as a combination of haemorrhage and tissue injury. The haemodynamic response to haemorrhage is well known. We wanted to examine the effect of injury on aspects of the haemodynamic and metabolic response to haemorrhage. Young Large White pigs, anaesthetised with alphaxalone/alphadolone (15 mg kg−1 h−1), were subjected to a haemorrhage of 30% of their total blood volume, with or without a background of brachial nerve afferent nociceptive stimulation (NS) to mimic injury. Shed blood was re-infused after a 30-min shock period. Haemodynamic, gut blood flow (GBF), and plasma lactate measurements were made and oxygen transport variables calculated and analysed using repeated measures ANOVA (Table 3). Haemorrhage (H) resulted in: (i) a tachycardia, (ii) hypotension, which recovered during the shock phase, (iii) a reduction in gut blood flow, which recovered during the shock phase, but, (iv) no increase in plasma lactate concentration. Nerve stimulation resulted in the expected ‘pressor response' of tachycardia and increased blood pressure. Trauma, modelled using haemorrhage with nerve stimulation (HNS), differed haemodynamically and metabolically from haemorrhage alone: there was, (i) no recovery of mean arterial pressure (MAP) during the shock phase (P So, the combination of haemorrhage plus injury (mimicked by afferent nociceptive stimulation) results in greater haemodynamic and metabolic disruption than haemorrhage alone. This needs to be considered in the development of better treatments for blunt trauma patients.