Pandit P B, Courtney S E, Pyon K H, Saslow J G, Habib R H
University of Medicine and Dentistry of New Jersey/Robert Wood Johnson Medical School, Camden, New Jersey, USA.
Pediatrics. 2001 Sep;108(3):682-5. doi: 10.1542/peds.108.3.682.
Constant-flow nasal continuous positive airway pressure (NCPAP) often is used in preterm neonates to recruit and maintain lung volume. Physical model studies indicate that a variable-flow NCPAP device provides more stable volume recruitment with less imposed work of breathing (WOB). Although superior lung recruitment with variable-flow NCPAP has been demonstrated in preterm neonates, corroborating WOB data are lacking.
To measure and compare WOB associated with the use of variable-flow versus constant-flow NCPAP in preterm neonates.
Twenty-four preterm infants who were receiving constant-flow NCPAP (means, SD) and had birth weight of 1024 +/- 253 g, gestational age of 28 +/- 1.7 weeks, age of 14 +/- 13 days, and FIO(2) of 0.3 +/- 0.1 were studied. Variable-flow and constant-flow NCPAP were applied in random order. We measured changes in lung volume and tidal ventilation (V(T)) by DC-coupled/calibrated respiratory inductance plethysmography as well as esophageal pressures at NCPAP of 8, 6, 4, and 0 cm H(2)O. Inspiratory WOB (WOB(I)) and lung compliance were calculated from the esophageal pressure and V(T) data using standard methods. WOB was divided by V(T) to standardize the results.
WOB(I) decreased at all CPAP levels with variable-flow NCPAP, with a maximal decrease at 4 cm H(2)O. WOB(I) increased at all CPAP levels with constant-flow CPAP. Lung compliance increased at all NCPAP levels with variable-flow, with a relative decrease at 8 cm H(2)O, whereas it increased only at 8 cm H(2)O with constant-flow NCPAP. Compared with constant-flow NCPAP, WOB(I) was 13% to 29% lower with variable-flow NCPAP.
WOB(I) is decreased with variable-flow NCPAP compared with constant-flow NCPAP. The increase in WOB(I) with constant-flow NCPAP indicates the presence of appreciable imposed WOB with this device. Our study, performed in neonates with little lung disease, indicates the possibility of lung overdistention at CPAP of 6 to 8 cm H(2)O with the variable-flow device. Further study is necessary to determine the efficacy of variable-flow NCPAP in neonates with significant lung disease and its use over extended periods of time.continuous-flow and variable-flow NCPAP, work of breathing, premature neonates, lung compliance.
持续气流经鼻持续气道正压通气（NCPAP）常用于早产儿以募集和维持肺容积。物理模型研究表明，可变气流NCPAP装置能提供更稳定的容积募集，且呼吸功（WOB）负担更小。尽管在早产儿中已证实可变气流NCPAP在肺募集方面更具优势，但缺乏相应的WOB数据佐证。
测量并比较早产儿使用可变气流与持续气流NCPAP时的WOB。
对24例接受持续气流NCPAP的早产儿进行研究，其平均出生体重为1024±253g，胎龄28±1.7周，年龄14±13天，吸入氧分数（FIO₂）为0.3±0.1。可变气流和持续气流NCPAP随机应用。通过直流耦合/校准呼吸感应体积描记法测量肺容积和潮气量（V(T)）的变化，以及在8、6、4和0cmH₂O的NCPAP水平下的食管压力。使用标准方法根据食管压力和V(T)数据计算吸气WOB（WOB(I)）和肺顺应性。将WOB除以V(T)以使结果标准化。
使用可变气流NCPAP时，在所有CPAP水平下WOB(I)均降低，在4cmH₂O时降幅最大。使用持续气流CPAP时，在所有CPAP水平下WOB(I)均升高。使用可变气流时，在所有NCPAP水平下肺顺应性均升高，在8cmH₂O时相对降低，而使用持续气流NCPAP时仅在8cmH₂O时升高。与持续气流NCPAP相比，可变气流NCPAP的WOB(I)低13%至29%。
与持续气流NCPAP相比，可变气流NCPAP可降低WOB(I)。持续气流NCPAP导致WOB(I)升高表明该装置存在明显的额外WOB负担。我们在肺部疾病较轻的新生儿中进行的研究表明，使用可变气流装置时，在6至8cmH₂O的CPAP水平下可能存在肺过度膨胀。有必要进一步研究以确定可变气流NCPAP在患有严重肺部疾病的新生儿中的疗效及其长期使用情况。持续气流和可变气流NCPAP、呼吸功、早产新生儿、肺顺应性。
