High-flow nasal cannula oxygenation bests apnoeic oxygenation during Foreign body removal by rigid bronchoscopy

Bronchoscopy often results in hypoxemia. Throughout the process, the partial pressure of oxygen (PaO2) typically declines by 20 mmHg, with the greatest reduction occurring during bronchoalveolar lavage. In order to prevent bronchoscopy-induced hypoxaemia, oxygen may be supplied by low or high gas fluxes. For oxygen treatment, the high-flow nasal cannula (HFNC) was launched recently. This device distributes heated, humidified air with a predetermined percentage of inspired oxygen (FiO2) and a maximum flow rate of 60 L/min through nasal prongs. It maintains blood oxygenation throughout the apnea stage of bronchoscopy, provides a flow-dependent positive airway pressure, and increases end-expiratory lung capacity to promote oxygenation. A recently published research compared the safety and effectiveness of oxygenation using a high-frequency nasal cannula (HFNC) to the usual apnoeic oxygenation approach during foreign body (FB) removal using a rigid bronchoscope.

Subjects slated for FB removal using a rigid bronchoscope participated in a prospective, blinded, randomized, controlled experiment. Men and women between the ages of 10 and 40 were considered for inclusion. The main result was the lowest oxygen saturation level measured by pulse oximeter during the surgery, while the secondary outcome was the incidence of postoperative atelectasis. Nearly 64 individuals were randomly assigned to either the HFNC oxygenation group (N = 32) or the apnoeic oxygenation group (N = 32). There were no statistically significant variations in age, gender, weight, or cardiovascular characteristics between the study groups. At various periods, intraoperative oxygen saturation was 4 percent greater in the HFNC group. The end-tidal carbon dioxide measured during induction and 15 minutes after termination did not differ significantly between the two groups; however, it was significantly higher in the apneic oxygenation group immediately after the procedure, 5 minutes after termination, and 10 minutes after termination. No deleterious effects were recorded as a result of the elevated end-tidal carbon dioxide levels.

Gas exchange is often reduced during bronchoscopy due to sedation and mismatching between ventilation and perfusion. Atelectasis may develop from increased airway resistance caused by the bronchoscope and gas aspiration via it. Positive end-expiratory pressure (PEEP) supplied by the HFNC seems to promote alveolar recruitment, increase functional residual capacity, and raise intrathoracic pressure during HFNC usage. In patients having rigid bronchoscopy for FB removal, HFNC was superior to apnoeic oxygenation in obtaining oxygen saturations greater than 92%. HFNC increased oxygen saturation and decreased end-tidal carbon dioxide levels in comparison to normal apneic oxygenation. Additionally, it resulted in fewer interruptions of the process and fewer bronchoscopy trial attempts.

References –

Twab, Samar M. Abdel,; Abdo, Fagr F.; Derh, Maha S. El High-flow nasal cannula oxygenation in comparison with apnoeic oxygenation during foreign body removal by rigid bronchoscopy: A randomised controlled trial, Indian Journal of Anaesthesia: May 2022 - Volume 66 - Issue 5 - p 344-349

doi: 10.4103/ija.ija_782_21