Zuiki Masashi, Naito Yuki, Kitamura Kazumasa, Tsurukawa Shinichiro, Matsumura Utsuki, Kanayama Takuyo, Komatsu Hiroshi
Department of Pediatrics, National Hospital Organization Maizuru Medical Center, 2410 Yukinaga, Maizuru, Kyoto, 625-8502, Japan.
Eur J Pediatr. 2021 Jan;180(1):241-246. doi: 10.1007/s00431-020-03761-x. Epub 2020 Aug 3.
Hypercapnia occurs in ventilated infants even if tidal volume (V) and minute ventilation (V) are maintained. We hypothesised that increased physiological dead space (V) caused decreased minute alveolar ventilation (V; alveolar ventilation (V) × respiratory rate) in well-ventilated infants with hypercapnia. We investigated the relationship between dead space and partial pressure of carbon dioxide (PaCO) and assessed V. Intubated infants (n = 33; mean birth weight, 2257 ± 641 g; mean gestational age, 35.0 ± 3.3 weeks) were enrolled. We performed volumetric capnography (V), and calculated V and V when arterial blood sampling was necessary. PaCO was positively correlated with alveolar dead space (V) (r = 0.54, p < 0.001) and V (r = 0.48, p < 0.001), but not Fowler dead space (r = 0.14, p = 0.12). Normocapnia (82 measurements; 35 mmHg ≤ PaCO < 45 mmHg) and hypercapnia groups (57 measurements; 45 mmHg ≤ PaCO) were classified. The hypercapnia group had higher V (median 0.57 (IQR, 0.44-0.67)) than the normocapnia group (median V/V = 0.46 (IQR, 0.37-0.58)], with no difference in V. The hypercapnia group had lower V (123 (IQR, 87-166) ml/kg/min) than the normocapnia group (151 (IQR, 115-180) ml/kg/min), with no difference in V.Conclusion: Reduction of V in well-ventilated neonates induces hypercapnia, caused by an increase in V. What is Known: • Volumetric capnography based on ventilator graphics and capnograms is a useful tool in determining physiological dead space of ventilated infants and investigating the cause of hypercapnia. What is New: • This study adds evidence that reduction in minute alveolar ventilation causes hypercapnia in ventilated neonates.
即使维持潮气量（V）和分钟通气量（V），机械通气的婴儿仍会出现高碳酸血症。我们推测，在机械通气良好但出现高碳酸血症的婴儿中，生理死腔（V）增加会导致肺泡分钟通气量（V；肺泡通气量（V）×呼吸频率）降低。我们研究了死腔与二氧化碳分压（PaCO）之间的关系，并评估了V。纳入了气管插管的婴儿（n = 33；平均出生体重，2257±641 g；平均胎龄，35.0±3.3周）。我们进行了容积式二氧化碳描记法（V），并在需要进行动脉血采样时计算V和V。PaCO与肺泡死腔（V）（r = 0.54，p < 0.001）和V（r = 0.48，p < 0.001）呈正相关，但与Fowler死腔无相关性（r = 0.14，p = 0.12）。将正常碳酸血症（82次测量；35 mmHg≤PaCO < 45 mmHg）和高碳酸血症组（57次测量；45 mmHg≤PaCO）进行分类。高碳酸血症组的V（中位数0.57（四分位间距，0.44 - 0.67））高于正常碳酸血症组（V/V中位数 = 0.46（四分位间距，0.37 - 0.58）），V无差异。高碳酸血症组的V（123（四分位间距，87 - 166）ml/kg/min）低于正常碳酸血症组（151（四分位间距，115 - 180）ml/kg/min），V无差异。结论：机械通气良好的新生儿中V降低会导致高碳酸血症，这是由V增加引起的。已知信息：•基于呼吸机图形和二氧化碳描记图的容积式二氧化碳描记法是确定机械通气婴儿生理死腔和研究高碳酸血症原因的有用工具。新发现：•本研究补充了证据，表明肺泡分钟通气量降低会导致机械通气新生儿出现高碳酸血症。
