ABSTRACT
The use of PETCO2 in detecting accidental bronchial intubation was investigated. The PETCO2 was measured in six mongrel dogs after occluding the left mainstem bronchus in three conditions; pentobarbital anaesthesia, 0.8% halothane insufflation together with pentobarbital anaesthesia, and simultaneous left pulmonary artery and bronchial airway occlusion with intravenous pentobarbital anaesthesia. An external flow probe measured left pulmonary artery blood flow. The PETCO2 decreased after bronchial occlusion during pentobarbital (35 +/- 3 vs 30 +/- 5 mmHg) and halothane-pentobarbital (30 +/- 6 vs 25 +/- 6 mmHg) conditions (P less than 0.05). However, within three minutes of bronchial occlusion, the values of PETCO2 had returned to their pre-occlusion values. After five minutes of bronchial occlusion pulmonary artery blood flow in the non-ventilated lung decreased (P less than 0.05) during pentobarbital (770 +/- 533 ml.min-1 vs 575 +/- 306 ml.min-1) and halothane-pentobarbital (495 +/- 127 ml.min-1 vs 387 +/- 178 ml.min-1) conditions. Simultaneous bronchial and pulmonary artery occlusion prevented any changes in PETCO2. It was concluded that accidental one-lung ventilation results in small and transient decreases in PETCO2. A redistribution of blood flow from the non-ventilated to ventilated lung occurs which restores PETCO2 to the original values observed with two-lung ventilation.
Subject(s)
Airway Obstruction/metabolism , Bronchi , Carbon Dioxide/metabolism , Intubation, Intratracheal/adverse effects , Pulmonary Circulation , Tidal Volume , Airway Obstruction/physiopathology , Animals , Blood Pressure/physiology , Carbon Dioxide/blood , Dogs , Halothane , Hypoxia/metabolism , Hypoxia/physiopathology , Intubation, Intratracheal/instrumentation , Lung/metabolism , Lung/physiopathology , Monitoring, Physiologic , Oxygen/blood , Pentobarbital , Pressure , Pulmonary Artery/physiopathology , Pulmonary Atelectasis/metabolism , Pulmonary Atelectasis/physiopathology , Pulmonary Circulation/physiology , Pulmonary Ventilation/physiology , Respiratory Dead Space/physiologyABSTRACT
A Doberman-German Shepherd cross-bred male dog, previously diagnosed as malignant hyperthermia susceptible, was mated to an unrelated nonsusceptible German Shepherd cross-bred female. The resultant litter was subjected to hematological, biochemical and erythrocyte osmotic fragility testing in an endeavor to predict the susceptibility of individuals to malignant hyperthermia. Laboratory evaluations were repeated at one year of age and the litter subjected to the halothane challenge test. No significant difference in erythrocyte osmotic fragility was found between malignant hyperthermia susceptible and nonsusceptible siblings at six weeks or at one year of age. Erythrocyte osmotic fragility, in both malignant hyperthermia susceptible and nonsusceptible animals, increased between six weeks and one year of age. Dantrolene sodium was an effective treatment for malignant hyperthermia in the dog when administered early in an episode and in adequate dosage. The initial sign of a malignant hyperthermia episode was a very rapid increase in end tidal partial pressure of carbon dioxide. This finding reinforces the value of capnographic monitoring in anesthesia.
