Reduction in minute alveolar ventilation causes hypercapnia in ventilated neonates with respiratory distress

Autor: Takuyo Kanayama, Kazumasa Kitamura, Yuki Naito, Utsuki Matsumura, Masashi Zuiki, Hiroshi Komatsu, Shinichiro Tsurukawa
Rok vydání: 2020
Předmět:
Zdroj: European Journal of Pediatrics
ISSN: 1432-1076
0340-6199
DOI: 10.1007/s00431-020-03761-x
Popis: Hypercapnia occurs in ventilated infants even if tidal volume (VT) and minute ventilation (VE) are maintained. We hypothesised that increased physiological dead space (Vd,phys) caused decreased minute alveolar ventilation (VA; alveolar ventilation (VA) × respiratory rate) in well-ventilated infants with hypercapnia. We investigated the relationship between dead space and partial pressure of carbon dioxide (PaCO2) and assessed VA. Intubated infants (n = 33; mean birth weight, 2257 ± 641 g; mean gestational age, 35.0 ± 3.3 weeks) were enrolled. We performed volumetric capnography (Vcap), and calculated Vd,phys and VA when arterial blood sampling was necessary. PaCO2 was positively correlated with alveolar dead space (Vd,alv) (r = 0.54, p < 0.001) and Vd,phys (r = 0.48, p < 0.001), but not Fowler dead space (r = 0.14, p = 0.12). Normocapnia (82 measurements; 35 mmHg ≤ PaCO2 < 45 mmHg) and hypercapnia groups (57 measurements; 45 mmHg ≤ PaCO2) were classified. The hypercapnia group had higher Vd,phys (median 0.57 (IQR, 0.44-0.67)) than the normocapnia group (median Vd,phys/VT = 0.46 (IQR, 0.37-0.58)], with no difference in VT. The hypercapnia group had lower VA (123 (IQR, 87-166) ml/kg/min) than the normocapnia group (151 (IQR, 115-180) ml/kg/min), with no difference in VE.Conclusion: Reduction of VA in well-ventilated neonates induces hypercapnia, caused by an increase in Vd,phys. 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.
Databáze: OpenAIRE