Capnometry after an inspiratory breath hold, PLATCO2, as a surrogate for PaCO2 in mild to moderate Pediatric Acute Respiratory Distress Syndrome: A feasibility study

Objective: Accurate and reliable noninvasive methods to estimate gas exchange are necessary to guide clinical decisions to avoid frequent blood samples in children with pediatric acute respiratory distress syndrome (PARDS). We aimed to investigate the correlation and agreement between end‐tidal PCO2 measured immediately after a 3‐s inspiratory‐hold (PLATCO2) by capnometry and PaCO2 measured by arterial blood gases (ABG) in PARDS. Measurements and Main Results: All patients were in volume‐controlled ventilation mode. The regular end‐tidal P P CO ETCO ( ) 2 2 (without the inspiratory hold) was registered immediately after the ABG sample. An inspiratory‐hold of 3 s was performed for lung mechanics measurements, recording PETCO2 in the breath following the inspiratory‐hold. (PLATCO2). End‐tidal alveolar dead space fraction (AVDSf) was calculated as [( – )/ PP P aCO ETCO aCO ] 2 2 2 and its surrogate (S)AVDSf as [( CO – )/ CO PLAT 2 ETCO PLAT 2 P ] 2 . Measurements of PaCO2 were considered the gold standard. We performed concordance correlation coefficient (ρc), Spearman's correlation (rho), and Bland–Altmann's analysis (mean difference ± SD [limits of agreement, LoA]). Eleven patients were included, with a median (interquartile range) age of 5 (2–11) months. Tidal volume was 5.8 (5.7–6.3) mL/kg, PEEP 8 (6–8), driving pressure 10 (8–11), and plateau pressure 17 (17–19) cm H2O. Forty‐one paired measurements were analyzed. PaCO2 was higher than PETCO2 (52 mmHg [48–54] vs. 42 mmHg [38–45], p < 0.01), and there were no significant differences with PLATCO2 (50 mmHg [46–55], p > 0.99). The concordance correlation coefficient and Spearman's correlation between PaCO2 and PLATCO2 were robust (ρc = 0.80 [95% confidence interval [CI]: 0.67–0.90]; and rho = 0.80, p < 0.001.), and for PETCO2 were weak and strong (ρc = 0.27 [95% CI: 0.15–0.38]; and rho = 0.63, p < 0.01). The bias between PLATCO2 and PaCO2 was −0.4 ± 3.5 mmHg (LoA −7.2 to 6.4), and between PETCO2 and PaCO2 was −8.5 ± 4.1 mmHg (LoA −16.6 to −0.5). The correlation between AVDSf and (S)AVDSf was moderate (rho = 0.55, p < 0.01), and the mean difference was −0.5 ± 5.6% (LoA −11.5 to 10.5) Conclusion: This pilot study showed the feasibility of measuring end‐tidal CO2 after a 3‐s end‐inspiratory breath hole in pediatric patients undergoing controlled ventilation for ARDS. Encouraging preliminary results warrant further study of this technique.

Citación

Pediatric Pulmonology, Vol. 58, N° 10 (2023) p. 2899-2905

Palabras clave

PARDS, Pediatric, Capnography, Mechanical ventilation

Licencia

Atribución-NoComercial-CompartirIgual 3.0 Chile (CC BY-NC-SA 3.0 CL)

Licencia URL

http://creativecommons.org/licenses/by-nc-sa/3.0/cl/

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