EFFECTS OF ALMITRINE BISMESYLATE IN A MICROSWINE MODEL OF HYPOXEMIC HYPOTHERMIA

We have developed an anesthetized microswine model of hypoxemic hypoth ermia and rewarming for testing prophylaxes and treatments. The respir atory stimulant almitrine bismesylate (ALM) was considered as a potent ial field expedient therapy for hypoxemic hypothermia. Preliminary exp eriments demonstrated that five consecutive 100 mu g.kg(-1) ALM intrav enous (iv) doses given to normothermic microswine 3-4 min apart increa sed minute ventilation from an average of 3.4 L.min-1 to 4.5 L.min(-1) (n = 2). However, when either a single iv ALM dose of 150 mu g.kg(-1) (n = 1) or three consecutive 100 mu g.kg(-1) iv doses given 15 min ap art (n = 1) to hypoxemic hypothermic microswine with a mean esophageal temperature (Tes) = 28.8 degrees C, and a mean arterial O-2 partial p ressure (PaO2) = 49 mmHg, the hypoxemia was potentiated (mean PaO2 = 3 2 mmHg) and respiratory arrest ensued. Other experiments using continu ous ALM iv infusion (1.0 mu g.kg(-1).min(-1)) in hypoxemic hypothermic microswine (n = 6, Tes = 30.6 +/- 0.5, PaO2 = 55.4 +/- 12.9) did not demonstrate significant (p less than or equal to 0.05) cardiorespirato ry differences (ventilation, heart rate, blood pressure, blood gases) when compared to hypoxemic hypothermic controls (n = 6, Tes = 30.7 +/- 0.5, PaO2 = 53.3 +/- 13.6). These results suggest that high dose iv b olus administration of ALM is not indicated as a potential field exped ient therapy for hyperemic hypothermia, while further work is required to assess the potential efficacy of other continuous low dose iv infu sion regimens.