Effects of positive end-expiratory pressure and 30% inspired oxygen on pulmonary mechanics and atelectasis in cats undergoing non-bronchoscopic bronchoalveolar lavage.

Objectives The objective of this study was to determine if modification of inspired oxygen concentration or positive end-expiratory pressure (PEEP) would alter bronchoalveolar lavage (BAL)-induced changes in pulmonary mechanics or atelectasis, as measured using ventilator-acquired pulmonary mechanics and thoracic CT. Methods Six experimentally asthmatic cats underwent anesthesia and non-bronchoscopic BAL, each under four randomized treatment conditions: 100% oxygen, zero PEEP; 30% oxygen, zero PEEP; 100% oxygen, PEEP 2 cmH2O; and 30% oxygen, PEEP 2 cmH2O. Pulse oximetry was used to estimate oxygen saturation (SpO2). Ventilator-acquired pulmonary mechanics and thoracic CT scans were collected prior to BAL and at 1, 5 and 15 mins post-BAL. Results While receiving 100% oxygen, no cat had SpO2 <91%. Some cats receiving 30% oxygen had decreased saturation immediately post-BAL (mean ± SD 70.8 ± 31%), but 6/8 of these had SpO2 >90% by 1 min later. There was a significant increase in airway resistance and a decrease in lung compliance following BAL, but there was no significant difference between treatment groups. Cats receiving no PEEP and 30% oxygen conserved better aeration of the lung parenchyma in BAL-sampled areas than those receiving no PEEP and 100% oxygen. Conclusions and relevance Alterations in pulmonary mechanics or atelectasis may not be reflected by SpO2 following BAL. The use of 30% inspired oxygen concentration failed to show any significant improvement in pulmonary mechanics but did diminish atelectasis. In some cats, it was also associated with desaturation of hemoglobin. The use of PEEP in this study did not show any effect on our outcome parameters. Further studies using higher PEEP (5-10 cmH2O) and intermediate inspired oxygen concentration (40-60%) are warranted to determine if they would confer clinical benefit in cats undergoing diagnostic BAL.

Multicenter evaluation of the administration of crotalid antivenom in cats: 115 cases (2000-2011).

OBJECTIVE: To evaluate use of crotalid antivenom, frequency of hypersensitivity reactions, and risk factors for hypersensitivity reactions and death in envenomed cats. DESIGN: Retrospective multicenter case series. ANIMALS: 115 envenomed cats treated with antivenom and 177 envenomed cats treated without antivenom. Procedures-Medical records from 5 institutions were searched by means of a multiple-choice survey with standardized answers for patient data including signalment, diagnosis, antivenom administration criteria, premedication, product, dose, administration rate, hypersensitivity reactions, and mortality rate. RESULTS: 95 of 115 (82.6%) cats received whole IgG antivenom, 11 (9.57%) received F(ab')2 antivenom, and 4 (3.48%) received Fab antivenom. The majority (101/115 [878%]) of cats received 1 vial of antivenom. In all cats, the median dilution of antivenom was 1:60 (range, 1:10 to 1:250) administered over a median period of 2.0 hours (range, 0.3 to 9.0 hours). There was no mortality rate difference between cats that did (6.67%) or did not (5.08%) receive antivenom. A type I hypersensitivity reaction was diagnosed in 26 of 115 (22.6%) cats. The use of premedications did not decrease type I hypersensitivity or improve mortality rate. Cats that had a type I hypersensitivity reaction were 10 times as likely to die as were those that did not have such a reaction. CONCLUSIONS AND CLINICAL RELEVANCE: The mortality rate of cats treated with antivenom was low. The administration of premedications did not improve mortality rate or prevent hypersensitivity reactions. The only variable associated with mortality rate was development of a type I hypersensitivity reaction. The rate of antivenom administration should be further evaluated as a possible risk factor for type I hypersensitivity reactions.