Effects of different fractions of inspired oxygen on gas embolization during hysteroscopic surgery: A double-blind randomized controlled trial

Background: Gas embolism is a common complication of hysteroscopic surgery, which causes serious concern among gynecologists and anesthesiologists due to the potential risk to the patients. The influencing factors of gas embolism in hysteroscopic surgery have been extensively studied. However, the effect of the oxygen concentration inhaled by patients on gas embolism during hysteroscopic surgery remains elusive. So, we designed a double-blind randomized controlled trial to determine whether different inhaled oxygen concentrations influence the occurrence of gas embolism during hysteroscopic surgery. Methods: This prospective, double-blind, randomized controlled trial enrolled 162 adult patients aged between 20 and 65 years undergoing elective hysteroscopic surgery who were randomly divided into three groups with fractions of inspired oxygen of 30%, 50% and 100%. Transthoracic echocardiography (4-chamber view) was used to evaluate whether the gas embolism occurred. Before the start of surgery, 4-chamber view was continuously monitored. Results: The number of gas embolism in group A, B and C was 36 (69.2%), 30 (55.6%) and 24 (44.4%) respectively. The incidence of gas embolism gradually decreased with the increase of inhaled oxygen concentration( P =0.031). Conclusions: In hysteroscopic surgery, a higher oxygen concentration inhaled by patients could reduce the incidence of gas embolism, indicating that a higher inhaled oxygen concentration, especially 100%, could be recommended for patients during hysteroscopic surgery. Trial registration Chinese Clinical Trial Registry(23/05/2020, ChiCTR2000033202)