Ruan Huijuan, Yang Qi, Zhao Xuelin, Tang Qingya, Feng Yi
Department of Clinical Nutrition, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China. Email:
Department of Cardiothoracic Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Asia Pac J Clin Nutr. 2025 Feb;34(1):66-75. doi: 10.6133/apjcn.202502_34(1).0006.
This study aimed to investigate the respiratory quotient (RQ) levels and its trend in the early postoperative period of patients with heart disease. Additionally, we explored factors influencing RQ and evaluated the predictive capabilities of RQ and lactic acid for various outcomes.
In this prospective observational study, participants included were heart disease patients aged 18-80 years who underwent elective open-heart surgery and were subsequently admitted to the cardiothoracic surgery ICU post-operation. Indirect calorimetry (IC) measurements were conducted on patients dur-ing the first three days after surgery to assess their RQ levels. Clinical data, including personal information, postoperative characteristics, and duration of surgery, were documented based on the patient's medical history.
In this study, 135 patients, of whom 57.04% were male, underwent a total of 247 IC measurements following cardiac surgery. On the first, second, and third days of admission to the ICU, the RQ values were 0.77±0.09, 0.80±0.07, and 0.78±0.05, respectively. The ROC curve analysis showed that on the first day of admission to the ICU, RQ was a better predictor of prolonged mechanical ventilation, LOS in ICU, and LOS in hospital compared to lactate level. However, on the second day of ICU admission, neither RQ nor lactate level could predict longer durations of mechanical ventilation, LOS in ICU, and LOS in hospital.
RQ may serve as a potential predictor for LOS in patients after cardiac surgery.
本研究旨在调查心脏病患者术后早期的呼吸商（RQ）水平及其变化趋势。此外，我们探讨了影响RQ的因素，并评估了RQ和乳酸对各种结局的预测能力。
在这项前瞻性观察研究中，纳入的参与者为年龄在18至80岁之间、接受择期心脏直视手术且术后入住心胸外科重症监护病房（ICU）的心脏病患者。在术后的头三天对患者进行间接测热法（IC）测量，以评估其RQ水平。根据患者的病史记录临床数据，包括个人信息、术后特征和手术时长。
在本研究中，135例患者接受了心脏手术后共247次IC测量，其中男性占57.04%。入住ICU的第一天、第二天和第三天，RQ值分别为0.77±0.09、0.80±0.07和0.78±0.05。ROC曲线分析表明，入住ICU的第一天，与乳酸水平相比，RQ是机械通气时间延长、ICU住院时间和住院时间的更好预测指标。然而，在入住ICU的第二天，RQ和乳酸水平均无法预测机械通气时间延长、ICU住院时间和住院时间。
RQ可能是心脏手术后患者住院时间的潜在预测指标。
