Objective To investigate the clinical efficacy of humidified high flow nasal cannula oxygen inhalation (HFNC) versus conventional nasal cannula oxygen inhalation on hypoxemia after complex ventral hernia surgery in elderly patients.

Methods The retrospective cohort study was conducted. The clinical data of 80 elderly patients with hypoxemia after complex ventral hernia surgery who were admitted to Huadong Hospital Affiliated to Fudan University from January 2021 to June 2022 were collected. There were 44 males and 36 females, aged (74±7)years. Of the 80 patients, 40 cases undergoing HFNC were allocated into HFNC group, and 40 cases undergoing conventional nasal cannula oxygen inhalation were allocated into conventional group, respectively. Observation indicators: (1) postoperative blood gas analysis; (2) postoperative complications. Measurement data with normal distribution were represented as Mean±SD, and comparison between groups was conducted using the independent sample t test. Measurement data with skewed distribution were represented as M(Q₁,Q₃), and comparison between groups was conducted using the rank sum test. Count data were represented as absolute numbers or percentages, and comparison between groups was conducted using the chi-square test or Fisher exact probability. Repeated measurement data were analyzed using the repeated ANOVA.

Results (1) Postoperative blood gas analysis. Before surgery and at 12 hours, 24 hours, 3 days after surgery, the partial pressure of blood oxygen was (13.5±2.3)kPa, (13.4±3.2)kPa, (13.8±2.3)kPa, (13.7±2.0)kPa for the HFNC group, and (12.7±2.1)kPa, (12.9±2.4)kPa, (12.3±2.5)kPa, (13.9±2.1) kPa for the conventional group. The partial pressure of carbon dioxide was (5.6±0.7)kPa, (5.0±0.6)kPa, (4.7±0.6)kPa, (4.9±0.6)kPa for the HFNC group, and (5.6±0.6)kPa, (4.4±0.8)kPa, (5.0±4.8)kPa, (5.1±1.1)kPa for the conventional group. The saturation of blood oxygen was 97.8%±2.2%, 98.1%±2.1%, 98.9%±1.8%, 99.2%±2.0% for the HFNC group, and 97.8%±3.1%, 97.8%±2.1%, 99.0%±1.5%, 98.8%±2.0% for the conventional group. The oxygenation index was 259±28, 300±45, 352±46, 353±57 for the HFNC group, and 262±29, 297±54, 304±63, 345±53 for the conventional group, respectively. There was a significant difference in the interven-tion effect of partial pressure of blood oxygen between the two groups (F_group=4.09, P<0.05) and no significant difference in the time effect or interaction effect (F_time=2.37, F_interaction=1.71, P>0.05). There were significant differences in the time effect and interaction effect of partial pressure of carbon dioxide between the two groups (F_time=7.23, F_interaction=13.21, P<0.05) and no significant difference in the intervention effect (F_group=1.02, P>0.05). There was a significant difference in the time effect of saturation of blood oxygen between the two groups (F_time=5.54, P<0.05) and no significant difference in the intervention effect or interaction effect (F_group=1.78, F_interaction=0.46, P>0.05). There were signifi-cant differences in the intervention effect, time effect, interaction effect of oxygenation index between the two groups (F_group=8.21, F_time=42.07, F_interaction=3.49, P<0.05). (2) Postoperative complications. The time in intensive care unit and cases with pulmonary infection were 3(3,3)days and 3 for the HFNC group, versus 6(5,7)days and 10 for the conventional group, showing significant differences between the two groups (Z=27.50, χ²=4.50, P<0.05). Cases with atelectasis and endotrachead intubation were 0 and 1 for the HFNC group, versus 4 and 7 for the conventional group, showing no significant difference between the two groups (P>0.05). There was no death in either group.

Conclusion Humidified high flow oxygen inhalation has certain advantages over conventional nasal cannula oxygen inhalation in improving partial pressure of blood oxygen and oxygenation index after complex ventral hernia surgery in elderly patients.