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- Author or Editor: Hélène Michaux x
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Objective—To describe the optimal thoracoscopic approach to the bovine pleural cavity and evaluate the short-term effects of thoracoscopy on cardiovascular and pulmonary function of healthy cattle.
Sample—6 healthy adult Holstein cows (12 hemithoraxes).
Procedures—For each cow, thoracoscopy was performed in both the left and right hemithoraxes with a 24-hour interval between procedures. Cows were sedated and restrained in a standing position for each thoracoscopic examination. Examination of each hemithorax lasted for 30 minutes. Arterial blood gas variables, heart rate, and respiratory rate were assessed at predetermined times before, during, and after the procedures to monitor cardiovascular and pulmonary function. Thoracic ultrasonography was performed immediately and at 24 hours and 1 week after each thorascopic examination to evaluate the extent of residual pneumothorax.
Results—Insertion of the laparoscope into the pleural cavity at the ninth intercostal space 15 cm ventral to the transverse processes of the thoracic vertebrae provided optimal visibility of structures in both the left and right hemithoraxes. Most structures of the pleural cavity were equally visible from both sides except the esophagus and the dorsal branch of the vagus nerve, which were best observed in the left hemithorax, and the pericardium, which was best observed in the right hemithorax. Mild increases in heart and respiratory rates and moderate decreases in arterial oxygen saturation and Pao2 were detected during the procedures.
Conclusions and Clinical Relevance—Standing thoracoscopy was well tolerated in healthy adult dairy cattle and needs to be evaluated in cattle with pulmonary disease.
Objective—To determine whether dobutamine stress tests (DST) can be used to detect cardiac dysfunction in dogs with early left ventricular dysfunction (ELVD) induced by rapid right ventricular pacing (RRVP).
Animals—7 adult male Beagles.
Procedure—A pacemaker was surgically implanted in each dog at the level of the right ventricular apex. Electrocardiography, Doppler sphygmomanometry, and Doppler echocardiography were performed before and during a DST prior to activation of the pacemaker and every 3 to 4 days during the period of RRVP. Dobutamine stress tests were performed by infusing dobutamine at incremental dosages ranging from 12.5 to 42.5 µg/kg of body weight/min.
Results—Clinical signs of congestive heart failure were not observed during the pacing period. However, all dogs developed ELVD associated with significant changes in values for most Doppler echocardiographic variables obtained prior to DST. Adverse cardiac effects were not detected during DST. Most Doppler echocardiographic indices of cardiac function were significantly altered in response to dobutamine infusion during the pacing period, compared with prepacing values. However, a dobutamine-induced 2-fold increase in cardiac output was maintained.
Conclusions and Clinical Relevance—Dobutamine stress tests can be safely performed in dogs with experimentally induced ELVD. Dobutamine stress tests may be a sensitive, noninvasive diagnostic method, complementary to standard clinical examinations, for detection of early cardiac dysfunction in dogs asymptomatic for dilated cardiomyopathy. (Am J Vet Res 2001;62:448–455)