Principles of mechanical ventilation.

Successful therapeutic mechanical ventilation of veterinary patients is one of the most rewarding aspects of critical care medicine. It requires an enormous commitment on the part of the hospital, including human and mechanical resources, as well as on the part of the owners or agents for the patient. The commitment of the latter is emotional as well as financial, and appropriate client education and communication are essential to a successful outcome. In this article, it is not the author’s intention to give exhaustive details regarding ventilator settings, drug dosages and regimens, or therapeutic strategies. Generally covered are indications for ventilation, the necessary setup and equipment for successful ventilation, some of the pitfalls and complications, and approaches to weaning ventilator patients. Each of these topics has generated complete texts and countless papers providing much greater detail. The goal of this article is to familiarize the practitioner with basic concepts behind all aspects of therapeutic ventilation. The list of references should provide a beginning for more detailed information. The basic cost per day for a patient on the ventilator at Angell Memorial Animal Hospital (AMAH) is $550.00–650.00. This covers the wear and tear and maintenance on the machine, some basic monitoring (pulse oximetry), and the oxygen supplied. The costs of blood gas measurement, blood pressure monitoring, catheter placements, medications, and fluids are all added on an individual basis. Not accounting for diagnostics and special procedures, the cost to the client can run $500.00 to $1000.00 per day. Is it worth it? As yet unpublished data from the Veterinary Medical Teaching Hospital at the University of California at Davis show that over a period of 7 years, 55% (22/40) of patients that were ventilated because of hypoventilation survived to be weaned. Twenty (50%) were discharged from the hospital alive. Twenty percent (9/45) of patients being ventilated because of hypoxemic respiratory failure were successfully weaned from the ventilator. Five (11%) of those weaned were discharged alive. Twelve animals were ventilated because of both hypercapnia and hypoxemia; of these, 4 (33%) were weaned and 2 (17%) were discharged alive. Overall survival to Vet Clin Small Anim 32 (2002) 1087–1100