Correlation between arterial oxygen and carbon dioxide levels and response to almitrine bismesylate in normal dogs

The objectives of this study were: 1) to test the action of small doses of almitrine bismesylate (0.004 mg/Kg body weight/min) on the arterial blood gases and on pulmonary and systemic circulation during hypoventilation under controlled mechanical ventilation; and 2) to investigate possible correlations between arterial blood. O2 and CO3 levels and the response to the drug. Twenty one dogs divided into two groups were studied under controlled ventilation in a double-blind fashion: hypoventilation + placebo (HP) (seven dogs); hypoventilation + almitrine (HA) (fourteen dogs). The results showed no significant variations of the gas ex-change and hemodynamic varibles in the HP group. In the HP group, during almitrine bismesylate infusion, despite the lack of variation in the pulmonary ventilation, the PaO2 increased from 46.1 torr to 51.7 torr, the PaCO2 decreased from 61.9 torr to 57.7 torr. There were no significant variations of hemodynamic variables in the HA group. Thus we conclude that the drug improved arterial blood gases (PaO2 increased) with small increase in alveolar ventilation (PaCO2 decreased) despite the lack of changes in pulmonary ventilation, and that the drug has action on the arterial PO2 potentiated by hypoxemia and hypercapnia

Gas exchange during differential mechanical ventilation after unilateral lung injury induced by hydrochloric acid: experimental study in dogs

In order to test gas exchange in lungs with unilateral injury, when mechanical ventilation is needed, three groups (G-I, G-II, G-III) of seven dogs each were studied. Injury was induced in the left lung by injecting 0,lN, 1.0 ml per kg of body weight of hydrochloric acid, pH = 2.00. For groups I and II a conventional volumetric artificial ventilator was used. G-I was the control group. In group II a bilateral positive end-expiratory pressure (PEEP) was introduced during the last phase (phase 3) of the experiment, and in group III, a prototype of a volume cycled ventilator, with separated bellows, was used delivering tidal volumes separately to each lung through a Carlens' tube. In G-III, PEEP was introduced only to the injured lung in the last phase of the experiment. Phase l (Fl), basal phase, was similar in the three groups; phase 2 (F2) was the period after instillation of hydrochloric acid and phase 3 was the period after a 5 cmH2O bilateral PEEP was used in G-II, and a selective PEEP to the left lung was used in G-III. In each phase of the experiment, hemodynamic and gas exchange variables were obtained. Our results allowed the following conclusions: the differential lung ventilation technique maintained the alveolar ventilation of the dogs and the differential lung ventilation with unilateral PEEP was better for gas exchange (phase 3) than the conventional ventilation with bilateral PEEP (CPPB).