Stroma-free hemoglobin-based oxygen carriers (HBOC) have been developed to overcome problems associated with transfusion of allogeneic blood. We have studied the efficacy of the first licensed veterinary blood substitute, hemoglobin glutamer-200 bovine (Oxyglobin; Biopure, Cambridge, MA, USA, Hb-200), in a canine model of acute hypovolemia and examined whether clinically commonly used criteria are adequate to guide fluid resuscitation with this product. Twelve anesthetized dogs were instrumented for measurements of physiological variables including hemodynamic, oxygenation, and blood gas and acid-base parameters. Dogs were bled to a mean arterial pressure (MAP) of 50 mmHg for 1 h followed by resuscitation with either shed blood (controls) or Hb-200 until heart rate (HR), MAP and central venous pressure (CVP) returned to baseline. Recordings were repeated immediately and 3 h after termination of fluid resuscitation. Hemorrhage (average 32 mL/kg) caused significant decreases in total hemoglobin (Hb), mean pulmonary arterial pressure (PAP), cardiac output (CO) and oxygen delivery (DO2I), increases in HR and systemic vascular resistance (SVRI), and lactic acidosis. In controls, only re-transfusion of all shed blood returned HR, MAP and CVP to prehemorrhage values, whereas in other dogs this endpoint was reached with infusion of 10 mL/kg Hb-200. Unlike blood transfusion, Hb-200 infusion failed to return CI and DO2I to baseline and to increase arterial oxygen content (CaO2) and total Hb; SVRI further increased. Thus, commonly used criteria (HR, MAP, CVP) to guide transfusion therapy in patients posthemorrhage prove insufficient when HBOCs with pronounced vasoconstrictive action are used and lead to inadequate volume repletion.

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When sheep rapidly eat a meal of dry feed a period of antinatriuresis and antidiuresis is rapidly initiated and lasts for 2-3 hrs. This is followed by a postprandial period of natriuresis and diuresis. This study tested the hypothesis that the postprandial natriuresis was due to a reduction in the secretion of aldosterone. In unanesthetized ewes of about 50 kg body wt, measurements were made of sodium and potassium excretion beginning in the terminal phase of the feed-induced antinatriuresis and continuing through the period of postprandial natriuresis. Aldosterone, given by constant infusion at a physiological dose (10 microgram/h), inhibited the natriuresis. Spironolactone, a competitive inhibitor of aldosterone given as a single intravenous injection of 5 mg/kg body wt, did not significantly increase the natriuresis. These results support the stated hypothesis. Neither aldosterone nor spironolactone had a significant effect on potassium excretion. This finding supports earlier view that aldosterone has only a small role in the homeostatic control of potassium excretion in sheep.

A modified procedure for infiltrating the coeliac plexus for the treatment of chronic pain syndromes is described. The injection of the analgesic is made through a fine needle introduced via a transabdominal approach under CT guidance. The advantages of this technique, compared with the dorsal approach, are a more accurate placement of the solution and the ability to carry out this procedure in very sick patients. No complications have been observed.