Abstract: Objective To explore the effect of mechanical ventilation on sublingual microcirculation and right heart function in patients with high altitude pulmonary edema (HAPE). Methods Thirty HAPE patients were randomly divided into HAPE group(conventional treatment) with 14 cases and MV group (mechanical ventilation treatment) with 16 cases, 20 healthy volunteers who did not develop HAPE were randomly selected as the control group. We performed tests including the total of perfused vessel density (TVD), perfused vessel density (PVD), proportion of perfused vessels (PPV) and microcirculation flow index (MFI), left and right diameter of right atrium, anteroposterior diameter of right ventricle, internal diameter of main pulmonary artery, pulmonary artery systolic pressure, blood gas analysis in HAPE group before-after treatment, after healing and in control group. At the same time, the lung rales, lung shadow disappearance time, and clinical cure time were observed in the MV group and HAPE group. Results Compared with the control group, the pH value of the MV group and the HAPE group increased before treatment; blood oxygen saturation (SaO₂) decreased; carbon dioxide partial pressure (PaCO₂) decreased; blood lactic acid (Lac) increased (P＜0.01). Compared with the HAPE group, the MV group relieved hypoxemia, respiratory alkalosis and reduced blood lactic acid more quickly after 2 h or 6 h treatment(P＜0.05 or P＜0.01). Compared with the control group, the TVD, PVD, PPV and MFI values of the MV group and the HAPE group were significantly lower than those before treatment (P＜0.01). The TVD, PVD, PPV and MFI values of the MV group increased after 24 h treatment, which were better than those of the HAPE group (P＜0.05). Compared with the control group, the left and right atrium diameters of the MV and HAPE groups increased before treatment, the anteroposterior diameter of the right ventricle, the inner diameter of the main pulmonary artery, and the pulmonary artery systolic pressure all significantly increased (P＜0.01). After treatment, the left and right diameters of the right atrium, the anteroposterior diameter of the right ventricle, the internal diameter of the main pulmonary artery, and the systolic pressure of the pulmonary artery all decreased in MV group and HAPE group. After 24-hour treatment, MV group was better than the HAPE group (P＜0.05). Compared with HAPE group, the MV group did shorten the disappearance time of lung rales and shadows, and the clinical cure time (P＜0.01). Conclusions Mechanical ventilation may quickly relieve hypoxemia, significantly improve microcirculation disorders and right heart failure, thereby shorten hospitalization of patients with HAPE.

Key words: rapidly entering the plateau, pulmonary edema, sublingual microcirculation, cardiac function