Objective To analyze the systemic, intestinal and cerebral perfusion after acute hemorrhage in a pediatric animal model.

Methods Experimental study in 10 mechanically ventilated piglets weighing 8.4±1 kg. Arterial and venous blood analysis, cerebral and somatic (renal site) near-infrared spectroscopy (NIRS), gastric tonometry and energy expenditure by indirect calorymetry were performed before, after withdrawal of 40 mL/kg of blood in 30 minutes, and 30 minutes later.

Results Acute hemorrhage produced a progressive decrease in arterial pH (7.38 to 7.28), arterial CO3H (26.4 to 19.5 mEq/L), venous PO2 (40.4 to 31.6 mmHg), venous oxygen saturation SvO2 (69.2 to 44.4%), gastric intramucosal pHi (7.19 to 6.99), cerebral saturation (52.4 to 39.4%), oxygen consumption (57.1 to 51 ml/min) and carbon dioxide production (27.9 to 19.7 ml/min) measured by indirect calorimetry. An increase of BE (basse exces) (2.5 to −7.6), lactic acid (0.9 to 5.6 mmol/l), venous PCO2 (52.2 to 59.2 mmHg), O2 arterial-venous gap (143.6 to 149.8 mmHg), and CO2 arterial-venous gap (5 to 18.6 mmHg) was observed. Non significant changes occurred in PaO2 (184 to 181 mmHg), SaO2(100 to 99.6%), renal saturation (59.6 to 56.2%) and energy expenditure (286.4 to 281.3 kcal).

Conclusions 1. Acute hemorrhage produced important alterations of systemic, cerebral and intestinal perfusion and lactic acidosis measured by arterial and venous blood gases, cerebral NIRS and gastric tonometry. 3. NIRS in renal site did not measure changes in somatic perfusion. 4. Indirect calorimetry measures did not correlate with arterial-venous blood gas differences.