| Research Abstract |
The effects of bupivacaine to asphyxia were evaluated in ventilated young dogs. Ten preparations were studied. Animals were assigned to one of two groups. The animals in group 1 ( n : 5 ) had a high FiO2 (Fio2 1.0 ), which was inflated to induce hyperoxemia (PaO2 511.5 18.2 mmHg : Mean SE) for study. The animals in group 2 ( n : 5 ) had a low Fio2 ( Fio2 0.16 ), which was inflated to induce asphyxia (PaO2 51,8 6.4 mmHg ) for study. The infusion rate of dupivacaine of 0.5 mg/kg/min during study. Measurements included electrocardiogram : heart rate, QRSinterval and pattern, blood pressure, arterial PH, and blood gases. In all animales, identical symptoms of toxicity occured in the following order : convulsions, hypotension, arrhythmia, and circulatory collapse. The dose of dupivacaine required to produce convulsion in the hypoxic dog tended to be lower than in the hyperoxemic dog, although the difference was not statistically significant ( P<0.1 ). However, the mean dose of bupivacain resulting in cardiovascular collaps was significantly lower in hypoxemic dog ( 37.6 8.4 mg/kg ) than in hyperoxemic dog ( 44.5 9.4 mg/kg ). Mean arterial blood pressure, heart rate, QRS interval on Eog, arterial PH, PaCO2 to infusion of bupivacaine in all animals were normal for our laboratory. In addition, the data indicate that the hypoxic dog may be more sensitive to the cardiotoxic effect of bupivacaine than the hyperoxemic animal.
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