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

Area of Science:

• Pulmonary Medicine
• Respiratory Physiology

Background:

• The intermittent apnea test (I-AT) is a standard procedure for assessing respiratory function.
• Concerns exist regarding the potential impact of I-AT on pulmonary gas exchange.

Purpose of the Study:

• To compare the reliability and safety of the classical I-AT with the continuous positive airway pressure apnea test (CPAP-AT).
• To evaluate the effect of I-AT on oxygenation and compare it to CPAP-AT.

Main Methods:

• A study involving 48 patients (Group O) compared I-AT and CPAP-AT.
• The PaO2/FiO2 ratio was measured before each test (T1 for I-AT, T2 for CPAP-AT).
• Patients were categorized into non-hypoxemic (N-H) and hypoxemic (H) subgroups.

Main Results:

• Overall, the PaO2/FiO2 ratio decreased significantly from T1 to T2 (321±128mmHg to 291±119mmHg, p=0.004).
• In the N-H subgroup, PaO2/FiO2 declined significantly (355±103 to 321±100mmHg, p=0.008).
• In the H subgroup, PaO2/FiO2 remained largely unchanged. Four patients in the N-H subgroup experienced a drop below 200mmHg at T2.

Conclusions:

• The intermittent apnea test (I-AT) may compromise pulmonary function.
• The findings support the CPAP-AT as a potentially safer alternative to I-AT for respiratory assessments.