Abstract

NATALINI, Cláudio Corrêa  and  POLYDORO, Alexandre da Silva. Effects of the high-flow modified to-and-fro anesthestic system on blood gas and respiratory rate in halothane anesthetized horses. Cienc. Rural [online]. 1997, vol.27, n.4, pp. 601-605. ISSN 0103-8478.  http://dx.doi.org/10.1590/S0103-84781997000400013.

Ten healthy adult horses male or female, mean body weight of 424±44.1kg, were anesthetized with romifidine, tiletamine/zolazepam and halothane for 60 minutes using a modified to-and-fro rebreathing anesthetic system, added of 1 liter mechanical dead space. The gas flow rate was 10 liters oxygen/minute during all inhalation anesthetic time. Variables analysed were arterial blood pH, carbon dioxide partial pressure (PaCO₂) and oxygen partial pressure (PaO₂), and respiratory rate (RR). The horses were allowed to breath spontaneously, and were positioned in right lateral recumbency the arterial O₂ values were significantly higher during halothane anesthesia when compared to the baseline values, and significantly lower after induction with tiletamine/zolazepam although arterial hypoxemia were not present. The arterial PaCO₂ values were significantly higher from baseline values during halothane anesthesia occurring arterial hypercapnia and mild respiratory acidosis. The arterial pH changes paralleled the changes in PaCO₂. Respiratory rate values were significantly lower during halothane anesthesia when compared to baseline values. All values remained within accepted range for lateral recumbent spontaneously breathing anesthetized horses.

Keywords : equine; horses; anesthesia; anaesthesia; halothane.