Apnea testing using the oxygen insufflation method for diagnosis of brain death may compromise pulmonary function

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Introduction:The aim of our study was to compare the reliability and safety of the classical I-AT with the continuous positive airway pressure apnea test (CPAP-AT).Material and methods:In the group of 48 patients (group O), an I-AT was performed at the end of BD diagnostic procedures, and approximately 1–1.5 h later CPAP-AT with 100% FiO2 and CPAP of 10 cm H2O, provided by ventilator in CPAP mode. After pre oxygenation with 100% FiO2 for 10 min, the PaO2/FiO2 ratio was recorded prior to I-AT at time-point one (T1) and prior to CPAP-AT at time-point two (T2). Group O was categorized into subgroup N-H (non-hypoxemic), consisting of 41 patients with good lung function, and subgroup H (hypoxemic) consisting of 7 patients with poor lung function. Within each subgroup PaO2/FiO2 at T1 and T2 were compared.Results:In Group O, PaO2/FiO2 decreased from 321 ± 128 mm Hg at T1 to 291 ± 119 mm Hg at T2 (p = 0.004). In subgroup N-H, PaO2/FiO2 declined from 355 ± 103 to 321 ± 100 mm Hg (p = 0.008), and in subgroup H, PaO2/FiO2 remained almost unchanged. Additionally, in 4 patients from subgroup N-H, PaO2/FiO2 decreased below 200 mm Hg at T2.Conclusions:Our study indicates that I-AT may compromise pulmonary function and this may support the recommendation of safer CPAP-AT alternative.HighlightsI-AT may compromise pulmonary function in some patientsIn some non-hypoxemic patients, PaO2/FiO2 ratio may decrease below the cutoff value of 200 mm Hg after I-AT.This may justify considering the alternative, safer CPAP-AT.

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