A Simple, Unique Field Ventilator for Large Ungulates: Another Use for Your Leaf Blower
Field anesthesia of wild ungulates commonly involves the use of opioid-based drug combinations. Hypoxemia, hypercarbia, and acidemia are common problems resulting from respiratory depression seen with opioid-based anesthesia. Oxygen supplementation and/or respiratory support are generally recommended when using opioids. Oxygen supplementation alone reduces hypoxemia but does not improve ventilation and gas exchange.1 Intermittent, positive-pressure, field ventilation has generally been accomplished in large ungulates by the use of single or multiple, in-series, high flow demand valves using 100% oxygen as the driving gas.3 These systems require pressurized oxygen tanks to be carried into the field, which is cumbersome and can be dangerous. Bellows-type ventilators are large, difficult to transport, and also require pressurized driving gases. Blower- or fan-driven ventilators have been used in veterinary medicine to ventilate large domestic species,4 including one using an electric vacuum cleaner as the drive source5. A simple, effective ventilator, utilizing either an electric or gas-powered leaf blower as the drive source, was designed to be used as an emergency field ventilator during a giraffe anesthesia study.2 This ventilator is made of commonly available parts, has a pop-off valve and pressure gauge to prevent over-inflation, an expiratory valve to provide post-expiratory end pressure (PEEP), and is relatively compact and easy to carry into the field. This device was used to ventilate three captive, sub-adult giraffe ranging in estimated weight from 580 to 700 kg. Inspiratory pressures of 20 cm H2O were reached quickly (<2 sec), paO2 values were significantly increased, and paCO2 values were significantly decreased over pre-ventilation values, indicating adequate ventilation efficiency.
This study was funded through a grant from the Morris Animal Foundation (#D03ZO-63).
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2. Citino, S.B., M. Bush, W. Lance, M. Hofmeyr, and D. Grobler. 2006. Use of thiafentanil (A3080), medetomidine, and ketamine for anesthesia of captive and free-ranging giraffe (Giraffa camelopardalis), Proc. Am. Assoc. Zoo Vet. Pp. 211–213.
3. Horne, W.A., M.N. Tchamba, and M.R. Loomis. 2001. A simple method of providing intermittent positive-pressure ventilation to etorphine-immobilized elephants (Loxodonta africana) in the field. J. Zoo Wildl. Med. 32:519–522.
4. Orima, H., M. Tagawa, H. Ejima, M. Shimizu, M. Fujita, and M. Washizu. 1992. Blower-driven artificial respirator for large animals. J. Vet. Med. Sci. 54:177–178.
5. Moore, A.G., J.D. McCrady, J. Vasku, M.E. Geddes, and H.E. Hoff. 1964. A respirator for large animals. Southwest Vet. 18:22–24.