PNEUMOTHORAX INDUCED BY CONTROLLED, CONTINOUS CO2 INFUSION IN HORSES: CLINICAL EVALUATION.

Abstract

Six male horses of varied age, weighing 424 ± 35.9 kg, were submitted to exploratory thoracoscopy in standing position. The horses were sedated with 0.06 mg/Kg of romifidine intravenously (i.v.), followed by 0.05 mg/Kg of butorphanol tartarate i.v. for analgesia, and infiltrative local anesthesia with approximately 20 mL of 2% lidocaine in the chosen access site. Animals were restrained in a stock during the entire procedure. Pneumothorax was induced by controlled CO2 infusion (maintained for 20 minutes). The following parameters were evaluated: occurrence of bilateral pneumothorax, initial and final intrathoracic pressure, and total CO2 volume used to sustain pneumothorax. Two, out of six animals developed bilateral pneumothorax. Residual pneumothorax was evaluated radiographically immediately after the procedure. Clinical parameters were assessed for five days following thoracoscopy, along with the evaluation of plasmatic fibrinogen levels. Except for plasmatic fibrinogen levels that peaked 72 hours after the procedure (p < 0.05), no differences were found in other parameters evaluated. We conclude that a 20-minute long pneumothorax during horacoscopy in horses is safe, leading to no significant post-operative clinical changes. The techniques employed here for accessing the thoracic cavity were effective in the induction and subsequent reduction of pneumothorax, reaching a full recovery of pre-existing negative intrathoracic pressure. KEY-WORDS: Pneumothorax. Thoracoscopy. Horses.