The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

A SAFER METHOD OF PERFORMING APNEA TESTS USING CARBOGEN AND CAPNOGRAPHY FOR PATIENTS ON APRV.

Maria G. Madden, Nader Habashi, Chris Kircher, Peter Saunders, Sabrina Cho, Ryan Martin; University of Maryland Medical Center/Shock Trauma, Baltimore, MD

Introduction: When evaluating brain death in traumatically injured patients, apnea testing is a preferred method for diagnosis determination. Unfortunately, due to the high acuity of injury, removing a patient from mechanical ventilation can lead to de-recruitment of the lungs and cause additional adverse side effects. For potential organ donors, the loss of recruitment may make it impossible for procurement of the lungs. To increase patient safety and limit adverse side effects, the use of carbogen has been approved for apnea testing in our facility. Using carbogen alleviates the need to remove the patient from mechanical ventilation, while leading to safer, more efficient results. The protocol targets pH and PaCO2 for the determination of a positive apnea test and evaluates ETCO2 to determine the test end point. Case Summary: The patient was on a Drager Evita XL. Settings were: APRV, Phigh of 28, Plow of 0, Thigh of 5.5 and a Tlow of 0.55 seconds. The patient was pre-oxygenated and PaCO2 normalized and ETCO2 was being monitored. The pre-apnea test ABG was used to determine the target ETCO2 to reach the target PaCO2 and pH using the formula: Initial pH – 7.20/0.006. Adjustments were made to minimize alarms during the test and automatic tube compensation (ATC) and oxygen monitoring were disabled. The ventilator’s air hose was connected to a carbogen tank (97% oxygen and 3% carbon dioxide). The Thigh was changed to 30 seconds, giving a release rate of 2 breaths per minute, and FIO2 set at 21%. During the test, ventilator waveforms and ETCO2 were monitored to identify any signs of spontaneous breathing. Results were achieved in 8 minutes and 50 seconds with no signs of lung de-recruitment. The formula was shown to be accurate in determining when the pH and PaCO2 would be met using ETCO2. Discussion: The carbogen apnea test provides less chance of pulmonary or cardiac side effects, predictable end point test compared to the standard apnea test, and a safer environment for the patient. Sponsored Research - None ABG AND VENTILATOR SETTINGS