Bartlett R H, Dechert R E, Mault J R, Ferguson S K, Kaiser A M, Erlandson E E
Surgery. 1982 Oct;92(4):771-9.
Despite the emphasis on surgical nutrition, clinical research and practice are usually based on gross estimation of caloric requirements and no specific knowledge of caloric balance. One reason for this is the difficulty of measuring O2 and CO2 exchange in critically ill patients. We designed a system for intensive care unit (ICU) bedside measurement of O2 consumption (VO2), CO2 production (VCO2), respiratory quotient (RQ), and indirect calorimetry (E). We measured these variables daily in 57 surgical ICU patients at risk for multiple organ failure. Measured VO2 and E varied widely (+/- 40%) from estimated values. Seventeen patients had a cumulative negative balance of at least 10,000 calories; 13 died. This caloric deficient was reversed by caloric intake in three of these patients; one died. Fifteen patients had positive caloric balance. Only four of these died, but the CO2 load produced by hypercaloric feeding created ventilator weaning problems in some patients. Ventilator weaning was facilitated by decreasing total calories and substituting fat for carbohydrate to reduce the RQ. The incidence of multiple organ failure was higher in patients with large caloric deficits, although cause and effect are not inferred. We conclude that respirometry and indirect calorimetry are helpful for management and essential for nutritional research.
尽管强调外科营养，但临床研究和实践通常基于对热量需求的粗略估计，且对热量平衡缺乏具体认识。造成这种情况的一个原因是在危重症患者中测量氧气和二氧化碳交换存在困难。我们设计了一种用于重症监护病房（ICU）床边测量氧气消耗（VO₂）、二氧化碳产生（VCO₂）、呼吸商（RQ）和间接热量测定（E）的系统。我们每天对57名有发生多器官功能衰竭风险的外科ICU患者测量这些变量。测量得到的VO₂和E与估计值相比差异很大（±40%）。17名患者累计热量负平衡至少10,000卡路里；13人死亡。其中3名患者通过热量摄入纠正了这种热量不足；1人死亡。15名患者热量平衡为正。这些患者中只有4人死亡，但高热量喂养产生的二氧化碳负荷在一些患者中导致了脱机困难。通过减少总热量并以脂肪替代碳水化合物以降低呼吸商，有助于脱机。热量严重不足的患者多器官功能衰竭的发生率更高，尽管不能推断因果关系。我们得出结论，呼吸测定法和间接热量测定法有助于管理，对营养研究至关重要。
