Effects and risks of hypothermia during blood purification in the treatment of postoperative cardiogenic shock in valvular heart diseases

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To implement hypothermia during blood purification to investigate its effect and risk in the treatment of postoperative cardiogenic shock in valvular heart disease. A non-blinded prospective randomized controlled trial (RCT) was conducted. Patients with valvular heart disease suffering from postoperative cardiogenic shock admitted to intensive care unit (ICU) of Wuhan Asian Heart Hospital from January 2011 to December 2014 were enrolled, and they were randomly divided into normothermic continuous blood purification (CBP) group (NT group) and hypothermia CBP group (HT group) according to random number table and envelope enclosed method. The patients in both groups were given continuous renal replacement therapy (CVVH), the blood temperature in NT group was remained at 36.5-37.3 °C , and it was controlled at 34.0-35.0 °C in HT group. The data were collected before and 1, 2, 3 days after treatment, including cardiac index (CI), the oxygen supply/oxygen consumption ratio (DO₂/VO₂), acute physiology and chronic health evaluation III (APACHE III) score, multiple organ dysfunction (MODS) score. The length of ICU stay, duration of mechanical ventilation, duration of CBP, ICU mortality and the incidence of complication were recorded. A total of 95 patients were enrolled, with 47 patients in NT group, and 48 in HT group. There was no significant difference in gender, age, preoperative cardiac function, cardiothoracic ratio and type of valve replacement between two groups. Compared with those before treatment, no significant difference was found in CI, DO₂/VO₂ ratio, APACHE III score, MODS score on 1, 2, 3 days after treatment in NT group (all P > 0.05). But in HT group, DO₂/VO₂ ratio was significantly improved on 1 day after treatment (2.5 ± 0.7 vs. 1.8 ± 0.4, P < 0.05), CI (mL · s⁻¹ · m⁻²: 50.01 ± 8.34 vs. 31.67 ± 11.67), APACHE III score ( 50.6 ± 6.2 vs. 77.5 ± 5.5), and MODS score (6.0 ± 1.5 vs. 9.3 ± 3.4) were significantly improved 3 days after treatment (all P < 0.05). Compared with those in NT group, DO₂NO2 ratio in HT group was significantly increased from 1 day after treatment (2.5 ± 0.7 vs. 1.8 ± 0.4, P < 0.05), and CI (mL · s⁻¹ · m⁻²: 38.34 ± 10.00 vs. 35.01 ± 6.67), APACHE III score (68.9 ± 7.1 vs. 81.2 ± 7.3), and MODS score (8.9 ± 2.7 vs. 10.6 ± 2.4) were significantly improved from 2 days after treatment (all P < 0.05). In respect of clinical outcomes, compared with NT group, the length of ICU stay (days: 6.9 ± 3.4 vs. 12.5 ± 3.5, t = 2.024, P = 0.017) and duration of mechanical ventilation (days: 4.2 ± 1.3 vs. 7.5 ± 2.7, t = 1.895, P = 0.034) in HT group was significantly shortened, duration of CBP was also significantly shortened (days: 4.6 ± 1.4 vs. 10.5 ± 4.0, t = 2.256, P = 0.019), and ICU mortality was significantly lowered (12.50% vs. 23.40, χ² = 1.987, P = 0.024), but there was no significant difference in incidence of infection (54.17% vs. 53.19%, χ² = 0.689, P = 0.341), ventricular arrhythmia (31.25% vs. 36.17%, χ² = 0.772, P = 0.237), and muscle fibrillation (14.58% vs. 8.51%, χ² = 0.714, P = 0.346), and blood loss (mL: 617.0 ± 60.7 vs. 550.9 ± 85.2, t = 1.290, P = 0.203) between HT group and NT group. The incidence of bradycardia in HT group was significantly higher than that of the NT group (29.17% vs. 14.89%, χ² = 2.368 P = 0.029). Blood purification under hypothermia is a safe and effective therapeutic procedure for postoperative cardiogenic shock in patients with valvular heart disease, and it may improve the prognosis of postoperative patients.