Objective To investigate the efficacy of a modified mask on patients with postoperative hypoxemia after cardiac surgery treated with high-flow nasal canula (HFNC).

Methods Sixty-eight patients undergoing cardiac surgery who developed hypoxemia after extubation were enrolled in the study and randomly divided into two groups using the random number table method for respiratory therapy with HFNC therapy and modified mask combined with HFNC, respectively. Respiratory and circulatory aspects at different time points (pre-treatment, 0.5 h, 1 h, 6 h, 24 h post-treatment), as well as reintubation rate of mechanical ventilation, treatment time, intensive care unit ICU stay and total hospital stay, incidence of pulmonary infections and in-hospital mortality were compared between the two groups.

Results Compared with the HFNC group, the modified mask combined with HFNC group showed statistically significant increase in partial pressure of oxygen (PaO₂) and improvements in oxygenation index (PaO₂/FiO₂) and decrease in respiratory rate (RR) (P < 0.05);the change in mean arterial pressure level (MAP) was significantly higher than that in the HFNC group (P < 0.05). There was no significant difference in pH, PaCO₂, Lac, HR, and left ventricular ejection fraction (LVEF) between the two groups (P>0.05). The reintubation rate of mechanical ventilation in the modified mask combined with HFNC group was lower than that in the HFNC group, and the treatment time and ICU stay were significantly shorter than those in the HFNC group (P < 0.05 to P < 0.01). The differences in total hospital stay, incidence of pulmonary infection and in-hospital mortality were not statistically significant (P>0.05).

Conclusions In patients with acute hypoxemia after cardiac surgery, a modified mask combined with HFNC therapy can increase PaO₂ without increasing PaCO₂, further improve oxygenation and circulation, and reduce treatment time, reintubation rate of mechanical ventilation, and ICU stay. However, there are no significant differences in total hospital stay, incidence of pulmonary infections, and in-hospital mortality between the two groups.