Microvascular gut oxygenation measured by Pd-porphyrin phosphorescence during severe hemorrhagic shock and low volume resuscitation with DCLHb^™in pigs

Introduction

Diaspirin crosslinked hemoglobin (DCLHb™, Baxter Healthcare Corp) is a hemoglobin based blood substitute which has been demonstrated to restore systemic blood pressure following hypovolemic shock at a low dose in pigs. In this study microvascular pO₂ of the pig gut (pO₂microv) was measured with a light guide attached to a phosphorimeter and using Pd-porphyrin quenching of phosphorescence [1], during shock and resuscitation. Resuscitation with DCLHb^™ was compared to resuscitation with a combination of crystalloid and colloid.

Methods

Ten pigs (16 kg) were anesthetized, and ventilated with 33% O₂ and 67% N₂. Catheters were inserted, a length of ileum was extracted from the peritoneal cavity, and the fibre of a phosphorimeter placed on the serosa of the last 10 cm of the ileum. During preparation, Pd-porphyrin bound to albumin was injected intravenously. After stable baseline (BL), a severe hemorrhagic shock was induced by withdrawing 40 ml/kg (50% of circulating blood volume) of blood over 1 h. After 45 min of shock (ES) all pigs were randomly assigned to two groups. Resuscitation was performed over 20 min with either DCLHb™ (10%, 5 ml/kg) (DCLHb, n = 5) or a combination of lactated Ringers' solution (75 ml/kg) and gelofusine (15 ml/kg) (coll/cryst, n = 5). Observations were made every 15 min for 2h after resuscitation. Pd-porphyrin measurements were performed every 20 s.

Conclusion

Low volume resuscitation with DCLHb™ in pigs results in a more sustained improvement of microvascular pO₂, measured by Pd-porphyrin phosphorescence, compared to resuscitation with a combination of large volume colloid and crystalloid.