ABSTRACT
Objective:To evaluate the changes in the systemic circulation and microcirculation in the patients undergoing gastrointestinal surgery under general anesthesia in Xining area.Methods:A total of 27 patients, aged 18-60 yr, underwent gastrointestinal surgery under general anesthesia in Xining area (2 260 m), of long lived (more than two generations) Han nationality, with no alternating life between plateau and plain, with no cardiopulmonary abnormalities, were enrolled.Anesthesia was induced with midazolam, sufentanil, etomidate, and cisatracurium and maintained with propofol, remifentanil and cisatracurium.At 5 min before induction of anesthesia (T 1), 10 min after induction of anesthesia (T 2), 1 h after start of operation (T 3), immediately after the end of operation (T 4), and 30 min after recovery from anesthesia (T 5), systemic circulation indexes including cardiac output (CO), stroke volume (SV), stroke volume variability (SVV), systemic vascular resistance index (SVRI), and mean arterial pressure (MAP) and heart rate (HR) were recorded, and sublingual microcirculation indexes including total vascular density (TVD), perfused vessel density (PVD), portion of perfused vessels (PPV), and microvascular flow index (MFI) were determined by sidestream dark field imaging. Results:Systemic circulation Compared with the baseline at T 1, CO and HR were significantly decreased at T 2-4, SVV was decreased at T 5, SVRI was increased at T 3 and T 4, and MAP was decreased at T 2 ( P<0.05). Compared with those at T 2, CO and SV were significantly increased at T 5, SVV was decreased at T 5, SVRI was increased at T 3 and T 4, and MAP was increased at T 4 and T 5 ( P<0.05). Compared with those at T 3, SV was significantly decreased at T 4, CO was increased at T 5, and SVV and SVRI were decreased at T 5 ( P<0.05); Compared with those at T 4, CO, SV and HR were significantly increased at T 5, and SVV and SVRI were decreased at T 5 ( P<0.05). Microcirculation Compared with those at T 1, TVD, PVD, PPV and MFI were significantly decreased at T 2-4, and PPV and MFI were decreased at T 5 ( P<0.05). Compared with those at T 2, TVD was significantly increased at T 5, PVD was increased at T 4 and T 5, and PPV was increased at T 3 and T 4 ( P<0.05). TVD was significantly higher at T 5 than at T 3( P<0.05). TVD was significantly higher at T 5 than at T 4 ( P<0.05). Conclusions:The density of microcirculation and blood flow rate are decreased after induction of general anesthesia and during anesthesia operation, which are most significant at the initial stage after induction, and decoupling between systemic circulation and microcirculation occurs during operation and anesthesia resuscitation in the patients at high altitude.