High-flow nasal oxygen reduces the incidence of hypoxia in sedated hysteroscopy for assisted reproduction

Abstract

Backgrounds and aims: Pain is the main reason for hysteroscopy failure. In day-surgical settings, hysteroscopy procedures are commonly performed with the patient under sedation. Hypoxia is the most common adverse event during sedation and can lead to severe adverse events. This study aimed to compare the incidence of hypoxia when using high-flow nasal oxygen (HFNO) with that when using regular nasal oxygen in patients undergoing hysteroscopy with sedation.

Materials and methods: In this single-center, prospective, randomized, single-blinded study, 960 female patients undergoing elective diagnostic or operative hysteroscopy were randomly enrolled into the following two groups: the regular nasal group [O₂ (3-6 L/min) covered by an HFNO] and the HFNO group [O₂ (30-60 L/min)] from September 2021 to December 2021. All women were sedated with propofol (1.5 mg/kg) and remifentanil (1.5 μg/kg) in the operating room. The primary outcome was the incidence of hypoxia (75% ≤ SpO₂ < 90%, < 60 s).

Results: HFNO decreased the incidence of hypoxia (75% ≤ SpO₂ < 90%, < 60 s), subclinical respiratory depression (90% ≤ SpO₂ < 95%) and severe hypoxia (SpO₂ < 75% for any duration or 75% ≤ SpO₂ < 90% for ≥ 60 s) from 24.38 to 0.83%, from 11.25 to 1.46% and from 3.75 to 0%, respectively (P < 0.001).

Conclusion: In procedures conducted to treat female infertility, HFNO can reduce hypoxia during hysteroscopy in patients sedated with propofol, and it can prevent the occurrence of subclinical respiratory depression and severe hypoxia.

Keywords: deep sedation; high-flow nasal oxygen; hypoxia; hysteroscopy; in vitro fertilization; propofol.

FIGURE 1

Surgical position, a hysteroscope and a high-flow nasal oxygen device. (A) Lithotomy position. (B) Outlook of the hysteroscope with a rigid 6.5-mm outer diameter and a 22° fore-oblique. (C) The 6.5-mm diameters of the hysteroscope. (D) Nasal cannula covered by the HFNO cannula. (E) High-flow nasal oxygen device and the parameters set in the study: adjustable temperature (37°C), gas flow (30–60 L/min) and oxygen concentration (100%).

FIGURE 2

CONSORT flowchart of study. HFNO, high-flow nasal oxygen.

FIGURE 3

Incidence of hypoxia events and their interventions. (A) Incidence of hypoxia events in both groups. Compared with the regular nasal group, HFNO significantly decreased the incidence of hypoxia (75% ≤ SpO2 < 90%, < 60 s), subclinical respiratory depression (90% ≤ SpO₂ < 95%) and severe hypoxia (SpO₂ < 75% for any duration or 75% ≤ SpO₂ < 90% for ≥ 60 s) from 24.38 to 0.83%, from 11.25 to 1.46% and from 3.75 to 0% (*P < 0.001, respectively). (B) Interventions during hypoxia. Compared with the regular nasal group, lower proportion in the HFNO group required oxygen improvement by jaw lifting or mask ventilation. In the regular nasal group, 132 patients needed their airway opened to relieve hypoxia, accounting for approximately 70% (69.84%) of the 189 patients; of these, 64 (33.86%) required jaw lifting and 68 (35.98%) required mask ventilation. However, in the HFNO group, only two patients required jaw lifting and two needed mask ventilation, which, respectively, accounted for 18.18% (^#P < 0.001, respectively). No patients were intubated in either group.

FIGURE 4

Diagram of the minimum SpO₂ during the procedure. The violin plot visually represents the distribution of minimum SpO₂. The minimum SpO₂ during the procedure was 98% [12% (53–100%)] in the regular nasal group and 100% [0% (86–100%)] in the HFNO group (⁺P < 0.001). In the regular nasal group, the dark dotted line represents the medium SpO₂ and is located at 98%, representing that most patients could maintain SpO₂ at 98%. The lowest dotted line at 53% indicates there had one patient who experienced severe hypoxia in the study. Almost all patients in the HFNO group were able to maintain an oxygenation level of 100%, and patients seldom experienced hypoxia. No patients in the HFNO group experienced severe hypoxia.