HAEMODYNAMIC ALTERATIONS SECONDARY TO ACUTE HAEMORRHAGE: A PROSPECTIVE EXPERIMENTAL STUDY

Objective To analyse the haemodynamic response to acute haemorrhage in a paediatric animal model. Methods Prospective experimental animal study in 10 mechanically ventilated piglets weighing 8.4 ± 1 kg, monitored with pulmonary thermodilution by Swan–Ganz catheter and femoral arterial thermodilution by the PiCCO method. Withdrawal of 40 ml/kg of blood in 30 minutes was performed. Modification of heart rate (HR), mean arterial pressure (MAP), central venous pressure (CVP), pulmonary capillary pressure (PCP), cardiac index (CI), systemic vascular resistance index (SVRI), left ventricular contractility (Dp/dtmax), intrathoracic blood volume index (ITBI), global end-diastolic volume (GEDV), extravascular lung water index (ELWI), stroke volume index (SVI) and systolic volume variation (SVV) was analysed. Results Haemorrhage produced a significant decrease in MAP (85.8 to 57.3 mm Hg), CI (4.5 to 2.8 l/min/m2), SVI (39.1 to 18 ml/m2), CVP (8.8 to 5.8 mm Hg), ITBI (738 to 413.6 ml/m2) and GEDV (193.5 to 121.6 ml), with a compensatory increase in HR (122.9 to 182.1 beats/min) and SVRI (1667 to 1864.6 dyn × cm5/m2). The haemodynamic alterations persisted 30 minutes after the end of blood extraction. Changes in the blood volume parameters (ITBI and GEDV) were larger than in the pressure parameters (CVP and PCP) and better correlated with CI modifications. There were no significant alterations of PCP, Dp/dtmax, ELWI and SVV. Conclusions Volume parameters (ITBI, GEDV and SVI) were more sensitive than pressure parameters (CVP and PCP) to measure haemodynamic alterations produced by haemorrhage. Systolic volume variation was not a sensitive indicator of hypovolaemia.