Thomas Edling

To determine whether end-tidal partial pressure of carbon dioxide (PETCO2) correlated with PaCO2 in isoflurane-anesthetized African grey parrots receiving intermittent positive pressure ventilation (IPPV). Prospective study. 14 healthy mature African grey parrots (Psittacus erithacus timnus). Each bird was anesthetized via mask with isoflurane, intubated, and connected to a pressure-limited intermittent-flow ventilator. Respiratory rate was altered while holding peak inspiratory pressure constant (5 cm H2O) to achieve a PETCO2 in 1 of 3 ranges: < 30 mm Hg, 30 to 40 mm Hg, and > 40 mm Hg. Blood was collected from the superficial ulnar artery of each bird at least once during each of the 3 ranges. Arterial blood samples were collected for blood gas analysis while PETCO2 was recorded simultaneously. A strong correlation between PETCO2 and PaCO2 was detected over a wide range of partial pressures, although PETCO2 consistently overestimated PaCO2 by approximately 5 mm Hg. End-tidal partial pressure of CO2 and PaCO2 also correlated well with arterial blood pH, and the acute response of the bicarbonate buffer system to changes in ventilation was similar to that of mammals. Results indicated that PETCO2 reliably estimates PaCO2 in isoflurane-anesthetized African grey parrots receiving IPPV and suggest that IPPV combined with capnography is a viable option for anesthetic maintenance in avian anesthesia.