Cardiopulmonary effects of bilateral hemithorax ventilation and diagnostic thoracoscopy in dogs.

OBJECTIVE

To describe alterations in respiratory and cardiovascular variables during diagnostic thoracoscopy, using bilateral hemithorax ventilation with sustained pneumothorax.

ANIMALS

7 adult dogs.

PROCEDURE

Each dog was anesthetized and instrumented for 2 episodes of cardiopulmonary monitoring that were performed at an interval of more than 14 days. The first anesthetic episode served as a control procedure for the thoracoscopy treatment performed during the second anesthetic episode. Multiple cardiopulmonary variables were evaluated by comparing changes from baseline values within treatments and between treatments.

RESULTS

Arterial oxygen tension decreased significantly from baseline values during thoracoscopy but was unchanged during sham treatment. Arterial carbon dioxide tension, clinical shunt fraction, and systemic mean arterial pressure increased during thoracoscopy. In contrast, these variables were unaffected by the sham treatment. Heart rate and cardiac index increased during sham and thoracoscopy treatments; however, the increase was significantly greater during thoracoscopy. Total peripheral vascular resistance significantly decreased from baseline values for both treatments, but the decrease was greater during thoracoscopy. Significant changes were not observed for oxyhemoglobin saturation or pulmonary vascular resistance during either treatment. Dogs recovered without major clinical complications.

CONCLUSIONS

Significant changes were found for several cardiopulmonary variables during bilateral hemithorax ventilation with sustained pneumothorax for diagnostic thoracoscopy of clinically normal dogs.

CLINICAL RELEVANCE

Diagnostic thoracoscopy with bilateral hemithorax ventilation and sustained pneumothorax is well tolerated in clinically normal dogs and may provide a diagnostic modality enabling intrathoracic procedures with less morbidity than thoracotomy for dogs with intrathoracic disease.