Bauer K, Ketteler J, Laurenz M, Versmold H
Department of Pediatrics, Freie Universität Berlin, Universitätsklinikum Benjamin Franklin, 12 200 Berlin, Germany.
Pediatr Res. 2001 Mar;49(3):394-401. doi: 10.1203/00006450-200103000-00014.
Energy expenditure measurements in ventilated preterm infants are difficult because indirect calorimetry underestimates energy expenditure during gas leaks around uncuffed endotracheal tubes routinely used in preterm infants or during nasal continuous positive airway pressure (CPAP). We, therefore, developed a breath collector that simultaneously sampled expired air expelled at the ventilator outlet and escaping via the tube leak from the infant's mouth and nose. Our breath collector was combined with a proprietary calorimeter (Deltatrac II). In vitro validation was done by methanol burning (VO(2), 13.8 mL/min; VCO(2), 9.2 mL/min) during intermittent positive pressure ventilation (IPPV) with two commonly used ventilators (Sechrist IV-100B and Infant Star). Measurement error was determined at different ventilator flows, peak inspiratory pressures of 12-24 cm H(2)O, and during a complete tube leak. The mean measurement error with both ventilators was low (VO(2) +/- 3 %, VCO(2) +/- 2 %) even during a complete tube leak and did not increase with peak inspiratory pressure. The system response time was 2 min. In vivo measurements at the bedside were performed in 25 preterm infants (body weight, 537-1402 g). Energy expenditure during IPPV was 40 +/- 9 kcal/kg per day and 46 +/- 15 kcal/kg per day during nasal CPAP. The tube leak in the preterm infants studied during IPPV was 0 to 47 %, and during nasal CPAP 84 to 97 %. In conclusion, indirect calorimetry performed with our breath collector was accurate during IPPV and nasal CPAP and was unaffected by tube leaks.
测量通气早产儿的能量消耗很困难，因为间接热量测定法会低估能量消耗，这发生在早产儿常规使用的无套囊气管内导管周围漏气期间，或鼻持续气道正压通气（CPAP）期间。因此，我们开发了一种呼气收集器，它能同时采集从呼吸机出口呼出的气体以及经婴儿口鼻处导管泄漏逸出的气体。我们的呼气收集器与一台专利热量计（Deltatrac II）相结合。通过使用两台常用呼吸机（Sechrist IV - 100B和Infant Star）进行间歇性正压通气（IPPV）期间甲醇燃烧（VO₂，13.8 mL/分钟；VCO₂，9.2 mL/分钟）来进行体外验证。在不同的呼吸机流量、12 - 24 cm H₂O的吸气峰压以及完全导管漏气期间测定测量误差。即使在完全导管漏气期间，两台呼吸机的平均测量误差都很低（VO₂±3%，VCO₂±2%），并且不会随吸气峰压增加。系统响应时间为2分钟。对25名早产儿（体重537 - 1402 g）进行了床边体内测量。IPPV期间的能量消耗为每天40±9 kcal/kg，鼻CPAP期间为每天46±15 kcal/kg。在研究的早产儿中，IPPV期间导管漏气率为0至47%，鼻CPAP期间为84至97%。总之，使用我们的呼气收集器进行间接热量测定法在IPPV和鼻CPAP期间是准确的，并且不受导管漏气影响。
