In morbidly obese patients with normal lungs, the use of postextubation continuous positive airway pressure (CPAP) support with a positive end-expiratory pressure (PEEP) of 12 cm H2O permits maintenance of the positive effects on pulmonary oxygenation achieved by mechanical ventilation; however, oxygenation does not persist after termination of CPAP. This was among findings of a randomized controlled trial presented at the American Thoracic Society (ATS) 2022 International Conference, held in San Francisco, California, May 13 to 18, 2022.
Investigators for the prospective trial, which was conducted in Germany, hypothesized that ventilation with individualized PEEP (PEEPIND) in combination with continuous CPAP support in the initial hours following extubation is associated with better oxygenation compared with the use of PEEP alone. Patients with a body mass index (BMI) of >35 kg/m2 who were scheduled to undergo bariatric laparoscopic abdominal surgery were included in the study. Participants were ventilated with PEEPIND, which was defined as “the PEEP value with the lowest regional ventilation inhomogeneity as determined by electrical impedance tomography (EIT) during a standardized decremental PEEP-trial.”
A total of 46 patients were enrolled in the study — 21 in the CPAP group and 25 in the control group. Overall, 20 of the participants were women. Patients were 44±12 years of age and had a mean BMI of 46.9±7.1 kg/m2.
Individuals in the CPAP arm received continuous CPAP support for 2 hours after extubation, compared with standard treatment for individuals in the control group, who received supplemental nasal oxygen insufflation to attain an oxygen saturation (SpO2) level of ≥90%, when necessary. Arterial oxygen partial pressure (PaO2)/fractional inspired oxygen (FiO2) ratio was measured 2 hours and 4 hours following extubation, respectively.
Results of the study showed that the median PEEPIND was 18 cm H2O, which did not differ significantly between the groups (P =.76). Although oxygenation (PaO2/FiO2 ratio) prior to extubation was comparable (P =.32), the PaO2/FiO2 ratio in the CPAP group was significantly higher during CPAP support (472±73 mm Hg in the intervention arm vs 317±72 mm Hg in the control arm; P <.001).
At 2 hours after termination of CPAP support, no significant differences in oxygenation were detected (365±141 mm Hg in the intervention group vs 317±72 mm Hg in the control group; P <.174).
The researchers concluded that despite the promising results shown with postextubation CPAP support in morbidly obese patients with normal lungs, the improvement in oxygenation did not persist after termination of CPAP support, suggesting atelectasis formation.
Girrbach F, Brechtelsbauer K, Hezel A, et al. Post-extubation CPAP support and oxygenation in morbidly obese patients — a prospective randomized controlled trial. Presented at: American Thoracic Society (ATS) 2022 International Conference; May 13-18, 2022; San Francisco, CA. Abstract P8.