Schmalisch G, Wauer R R
Abteilung Neonatologie, Humboldt-Universität zu Berlin.
Pneumologie. 1995 Aug;49(8):461-5.
Ventilatory measurements especially in preterm infants are hampered by the additional apparatus dead space (face mask, pneumotach, shutter, ...). The apparatus dead space can be higher than the physiological dead space and affects gas exchange and blood gases significantly. For lung function testing in premature or term infants a background flow (flow-through technique) is frequently used to eliminate the apparatus dead space. This background flow must be higher than the maximum inspiratory flow (maxVin). For its optimization ventilatory measurements were performed in 62 sleeping infants aged 2 to 28 days (birth weight 760-5000 g). maxVin correlated strongly with minute ventilation VE (r = 0.90; p < 0.001). The ratio maxVin/VE decreased significantly (p < 0.05) with increasing frequency: from 4.4 +/- 0.8 (f < 40/min); 4.1 +/- 0.7 (f = 40-59/min); 3.8 +/- 0.5 (f = 60-79/min) to 3.4 +/- 0.4 (f > 80/min). With increasing frequency the flow signal becomes sinusoidal and the ratio maxVin/VE tends to pi. Therefore, during tidal breathing the background flow should be at least three but not more than the six times VE to avoid an impairment of measurements.
通气测量，尤其是在早产儿中，会受到额外的仪器死腔（面罩、呼吸流速计、快门等）的影响。仪器死腔可能高于生理死腔，并对气体交换和血气产生显著影响。对于早产儿或足月儿的肺功能测试，通常采用背景气流（流通技术）来消除仪器死腔。这种背景气流必须高于最大吸气流量（maxVin）。为了优化通气测量，对62名年龄在2至28天（出生体重760 - 5000克）的睡眠婴儿进行了通气测量。maxVin与分钟通气量VE密切相关（r = 0.90；p < 0.001）。随着频率增加，maxVin/VE比值显著降低（p < 0.05）：从4.4 ± 0.8（f < 40次/分钟）；4.1 ± 0.7（f = 40 - 59次/分钟）；3.8 ± 0.5（f = 60 - 79次/分钟）降至3.4 ± 0.4（f > 80次/分钟）。随着频率增加，流量信号变为正弦波，maxVin/VE比值趋于π。因此，在潮气呼吸期间，背景气流应至少为VE的三倍，但不超过六倍，以避免测量受到影响。
