High alveolar-arterial oxygen and end tidal-arterial carbon dioxide gradients in mechanically ventilated rats

摘要

During the course of a study involving rats lightly anesthetized with an inhalation agent, paralyzed with a neuromuscular blocking agent, and mechanically ventilated, arterial oxygen partial pressure (P_aO_2) was consistently lower than anticipated. There was also a discrepancy between end tidal carbon dioxide (EtCO_2) concentration and arterial CO_2 partial pressure (P_aCO_2). The studies were approved by the Texas Tech University Health Sciences Center (TTUHSC) Animal Care and Use Committee. Prior to study, the animals, outbred Sprague Dawley (CrhCD[SD]BR) male rats from Charles River Laboratories, Wilmington, Mass. weighing 250 g on average were housed in shoebox cages with hardwood chip contact bedding (P.J. Murphy, Montville, N. J.) in the TTUHSC Laboratory Animal Care Facility. Water and food (Harlan Teklad Rodent Diet 8640; Harlan Teklad, Bartonville, III.) were provided ad libitum, and a 12/12-h light/dark cycle was used. Air changes averaged between 12 to 15/h.