碳水化合物热卡摄入比例变化对重症慢性阻塞性肺病患者通气和代谢的影响

目的：比较10例重症COPD患者在机械通气时，进行等热量不同碳水化合物热卡比例的全胃肠外营养，观察COPD患者通气及代谢的变化。方法：应用间接热卡仪测定能量需要量，给予三种等热量不同碳水化合物热卡的营养液，即40％糖、40％脂肪、20％蛋白质，60％糖、20％脂肪、20％蛋白质和75％糖、5％脂肪、20％蛋白质，并用间接热卡仪测定二氧化碳产生量（VCO2）、氧耗量（VO2）、呼吸商（RQ）、每分通气量（VE）、肺泡通气量（VA）、死腔通气量（Vd），并测定二氧化碳分压（PaCO2）等通气及代谢参数。结果：随着碳水化合物热卡摄入比例的增加，COPD患者的VCO2、VO2、RQ、VE、VA、Vd、PaCO2等通气及代谢指标均无显著变化，碳水化合物热卡摄入量与VCO2、VE、VA、PaCO2无显著相关关系，而RQ与VA呈显著正相关（r＝0．439，P＜0．05）。结论：在COPD患者的营养支持中，合理能量的摄入对减少营养支持并发症的发生更为重要。

Metabolic and respiratory effects of carbohydrate calories in patients with COPD during mechanical ventilation

Objective: The cause of nutritionally related hypercapnia is generally thought to be excess carbohydrate(CHO) or glucose calories. To assess the effect of carbohydrate calories on CO2 metabolism and ventilation, this study evaluated patient resPonses to carbohydrate loads on measured metabolic and respiratory parameters. Methods: Using indirect calorimetry, carbon dioxide production (VCO2), oxygen consumption (VO2), exhaled minute ventilation (VE) as well as the derived variables of respiratory quotient (RQ), deadspace ventilation (Vd) and alveolar ventilation (VA) were pefored in 10 mechanically ventilated patients with COPD, who received TPN in the form of three isocarloric nutritional regimens;40 percent CHO/40 percent fat/20 percent protein,60 percent CHO/20 percent fat/20 percent protein.Caloric requirements were based on meastired energy expenditure by indirect calorimetry. Arterial blood gas analysis was measured stimultancously. Results: VCO2, CO2, RQ, VE. VA. Vd' and PaCO2 did not change with increasing CHO proportion. The carbohydrate caloric intake showed no correlations to VC2,VE, VA, and PaCO2. There was not a significant correlation between VCO2 and VE, but RQ showed a significant correlation to VA(r =0. 439, P < 0.05). Conclusions: Our data suggested mederate caloric intake appears to be more important in avoiding nutritionally related increases in VCO2 in mechanically ventilated patients with COPD.