[Clinical study on echocardiography combined with end-tidal CO2 monitoring in preventing the venous air embolism during operative hysteroscopy].

OBJECTIVE: To explore the value of transthoracic echocardiography(TTE) combined with partial pressure of end-tidal CO2 (P ETCO2) monitoring in preventing venous air embolism(VAE) during hysteroscopy operation.

METHODS: From August 2010 to August 2012, 300 cases undergoing hysteroscopic surgery under general anaesthesia were enrolled in this study. With the echocardiography combined with P ETCO2 monitoring during hysteroscopic surgery, the time of VAE appearing in the right atrium , the extent of air embolism(grade 0-4), the changes of P ETCO2, peripheral oxygen saturation (SpO2), blood pressure (Bp), the amount of fluid intravasation and the blood loss were recorded in detail . Take the 24 cases that the grades of VAE in grade 3 or above and a decrease in P ETCO2 ≥ 5 mm Hg (1 mm Hg = 0.133 kPa) as intervention group. Stop operation immediately, the left side and raise your right shoulder, oxygen inhalation and dexamethasone 10 mg intravenous drip were given to the intervention group; the control group (5 cases in grade 3 or above and a decrease in P ETCO2<5 mm Hg) only stop operation immediately, observation patient's condition closely.

RESULTS: (1) The occurrence of VAE: air embolism occurred in 34 patients among all 300 patients, all of 34 patients had evidence of gas embolism in the inferior vena cava, right atrium(RA) and right ventricle chamber, and 29 patients had evidence of continuous groups of gas emboli. There were 32 cases with the decrease in P ETCO2 > 2 mm Hg, 14 cases with SpO2 less than 95%, and 4 cases with a drop in Bp ≥ 20%. (2) The change of the decrease of P ETCO2 and the grades of VAE: the decrease of P ETCO2 and the grades of VAE were positively correlated (r = 0.601, P < 0.01), continuous groups of gas emboli signal in RA, when the drop of P ETCO2 ≥ 5 mm Hg, 8 of the 34 cases whose drop of P ETCO2 ≥ 10 mm Hg, 7 cases in grades 4. The decrease of P ETCO2 [(7.5 ± 2.4) mm Hg versus (11.1 ± 4.1) mm Hg], the amount of fluid intravasation[(688 ± 150) ml versus (925 ± 268) ml] and the blood loss[(71 ± 36) ml versus (127 ± 56) ml] all had statistical difference in grade 3 and 4 (P < 0.05) . The sensitivity of P ETCO2 was better than SpO2 and Bp in detecting of VAE. (3) The cases of P ETCO2 continue to decline and recovery time between the two groups:2 cases' P ETCO2 continued to decline in the intervention group, but 4 cases in the control group. The recovery time of the two groups was (4.8 ± 1.6) and (8.3 ± 1.9) min, respectively, which reached statistical difference between (P < 0.05).

CONCLUSIONS: TTE combined with P ETCO2 monitoring can effectively predict the occurrence of air embolism in hysteroscopic surgery; Continuous groups of gas emboli signal in RA accompanied by a decrease in P ETCO2 ≥ 5 mm Hg indicates that the occurrence of air embolism; the more the amount of intravasation of distension fluid and the blood loss, the more the air into the body. Timely intervention can effectively prevent the development of air embolism when the VAE in grade 3 or above accompanied by a decrease in P ETCO2 ≥ 5 mm Hg.