細野 茂春

Abstract Background Providing positive‐pressure ventilation (PPV) to the lungs is essential for neonatal resuscitation. Accurate PPV requires a precise measurement of tidal volume and airway pressure, with airway obstruction and mask leakage being the primary concerns for ineffective ventilation. This study aimed to investigate the differences between tidal volume and airway pressure measured by a respiratory function monitor (RFM) and the actual values delivered to the lungs in scenarios involving mask leaks, using a system comprising a PPV device, a face mask, and an artificial lung model. Methods Three experiments were conducted to assess mask leakage (1) under varying lung conditions, (2) under different ventilation rates, and (3) using different PPV devices. Two RFMs were used, one in the test lung and the other in the mask. Trends in those data were assessed by means of a correlation graph. Results Mask leakage resulted in an underestimation of the actual tidal volume, with the effect intensifying as the leak percentage increased. PPV devices using a compressed gas source demonstrated less reduction in lung tidal volume (from 15 to 12 mL) owing to mask leaks compared with those without such a source (from 16 to 5 mL). Conclusions Significant discrepancies were observed between RFM readings and test lung values for tidal volume. These findings highlight the importance of accurate monitoring to prevent lung injury caused by excessive tidal volume, particularly in the presence of mask leaks. Accurately measuring tidal volume in the presence of mask leaks presents a significant challenge for the future.

BACKGROUND: The objective of the present study was to verify the speed and accuracy of fetal ultrasonic Doppler (fetal Doppler) in measuring heart rate of newborns at rest, including preterm, low-birthweight infants, and its efficacy during neonatal resuscitation, including cases of neonatal asphyxia. METHODS: A three-lead electrocardiogram and fetal Doppler were used to measure resting heart rates in 100 newborns, including 48 preterm, low-birthweight infants, at 0 to 72 h after birth. Times to display heart rate were compared between electrocardiogram and fetal Doppler by the Bland-Altman analysis and Wilcoxon signed-rank test. The time required for the fetal Doppler to measure heart rate during neonatal resuscitation was also assessed. RESULTS: In 100 newborns, the mean error of the resting heart rate in 1,293 measurement points was 0.07 beats/min. To display the heart rate, the fetal Doppler required a median time of 5 s, and electrocardiogram required a median time of 10 s (P < 0.001). During neonatal resuscitation, the heart rate was measured within 10 s in 18 of 21 cases (86%) and displayed with a median time of 5 s; this was measured in all neonatal asphyxia cases (9/9, 100%). CONCLUSIONS: Fetal Doppler can measure heart rate in newborns accurately and rapidly and is useful for evaluating heart rate not only at rest but also during neonatal resuscitation, especially in asphyxia.