TY - JOUR T1 - Apnea testing: the effects of insufflation catheter size and flow rate on pressure and volume within a test lung JF - Respiratory Care DO - 10.4187/respcare.02499 SP - respcare.02499 AU - Nicholas R. Henry AU - S. Gregory Marshall Y1 - 2013/08/20 UR - http://rc.rcjournal.com/content/early/2013/08/20/respcare.02499.abstract N2 - Background: The apnea test (AT) is used to determine the absence of a respiratory drive when determining brain death. Current guidelines for performing the AT do not specify the size of insufflation catheter (IC) to use with each endotracheal tube (ETT) size despite previous case reports describing procedure-related complications with the use of varying IC sizes. The objective of this study is to identify an appropriate size of IC to use with each ETT size as a way to minimize the generated pressure and volume within the lungs when performing the AT. Methods: ETT sizes 6.0-10.0mm were inserted into an intubation manikin connected to a test lung sequentially. The peak pressures and volumes generated within the test lung were recorded when performing the AT using IC sizes 10-16 French and “cut oxygen supply tubing” at oxygen flow rates of 6-15 Lpm. The MANOVA and Tukey’s HSD statistical methods were used to analyze data at an alpha level of 0.05. Results: The MANOVA method identified significant differences among pressures and volumes when performing the AT (p<0.001) and the Tukey’s method identified significant differences among the pressures and volumes associated with IC:ETT ratios ≥0.7 and IC:ETT ratios <0.7 (p<0.05). Conclusions: Selection of an IC with an external diameter <70% of the ETT internal diameter at 6 Lpm may prevent increased pressures and volumes within the lungs while performing the AT. This recommendation coupled with current American Academy of Neurology guidelines for the determination of brain death may reduce the incidence of procedure related complications. ER -