Accuracy evaluation of mainstream and sidestream end-tidal carbon dioxide monitoring during noninvasive ventilation: a randomized crossover trial (MASCAT-NIV trial)

Masaaki Sakuraya; Eri Douno; Wakana Iwata; Akihiro Takaba; Kosuke Hadama; Natsuki Kawamura; Toshinori Maezawa; Kei Iwamoto; Yuya Yoshino; Kenichi Yoshida

doi:10.1186/s40560-022-00603-w

Accuracy evaluation of mainstream and sidestream end-tidal carbon dioxide monitoring during noninvasive ventilation: a randomized crossover trial (MASCAT-NIV trial)

J Intensive Care. 2022 Mar 18;10(1):17. doi: 10.1186/s40560-022-00603-w.

Authors

Masaaki Sakuraya¹, Eri Douno^{2

3}, Wakana Iwata², Akihiro Takaba², Kosuke Hadama², Natsuki Kawamura², Toshinori Maezawa², Kei Iwamoto^{2

4}, Yuya Yoshino^{2

5}, Kenichi Yoshida²

Affiliations

¹ Department of Emergency and Intensive Care Medicine, JA Hiroshima General Hospital, Jigozen 1-3-3, Hatsukaichi, Hiroshima, 738-8503, Japan. masaaki.sakuraya@gmail.com.
² Department of Emergency and Intensive Care Medicine, JA Hiroshima General Hospital, Jigozen 1-3-3, Hatsukaichi, Hiroshima, 738-8503, Japan.
³ Department of Emergency and Critical Care Medicine, Urasoe General Hospital, Okinawa, Japan.
⁴ Critical Care Medical Center, Hiroshima Prefectural Hospital, Hiroshima, Japan.
⁵ Emergency and Critical Care Center, Kurashiki Central Hospital, Okayama, Japan.

Abstract

Background: The end-tidal partial pressure of carbon dioxide (P_ETCO₂) can be used to estimate the arterial partial pressure of carbon dioxide (PaCO₂) in patients who undergo mechanical ventilation via endotracheal intubation. However, no reliable method for measuring P_ETCO₂ during noninvasive ventilation (NIV) has been established. The purpose of this study was to evaluate the correlation and agreement between PaCO₂ and P_ETCO₂ measured by these two methods and to compare them in patients who underwent NIV after extubation.

Methods: This study was a randomized, open-label, crossover trial in a mixed intensive care unit. We included patients who were planned for NIV after extubation and for whom the difference between P_ETCO₂ and PaCO₂ was ≤ 5 mmHg. We compared mainstream capnography using an inner cup via face mask (the novel method) with sidestream capnography (the previous method) during NIV. The relationships between PaCO₂ and P_ETCO₂ were evaluated by computing the Pearson correlation coefficient, and the agreement between PaCO₂ and P_ETCO₂ was estimated using the Bland-Altman method.

Results: From April 2020 to October 2021, 60 patients were included to the study. PaCO₂ and P_ETCO₂ were well correlated in both methods (the novel methods: r = 0.92, P < 0.001; the previous method: r = 0.79, P < 0.001). Mean bias between PaCO₂ and P_ETCO₂ measured using the novel method was 2.70 (95% confidence interval [CI], 2.15-3.26) mmHg with 95% limits of agreement (LoA) ranging from - 1.61 to 7.02 mmHg, similar to the result of measurement during SBT (mean bias, 2.51; 95% CI, 2.00-3.02; 95% LoA, - 1.45 to 6.47 mmHg). In contrast, measurement using the previous method demonstrated a larger difference (mean bias, 6.22; 95% CI, 5.22-7.23; 95% LoA, - 1.54 to 13.99 mmHg).

Conclusion: The current study demonstrated that the novel P_ETCO₂ measurement was superior to the previous method for PaCO₂ prediction. During NIV, the novel method may collect as sufficient exhalation sample as during intubation. Continuous P_ETCO₂ measurement combined with peripheral oxygen saturation monitoring is expected to be useful for early recognition of respiratory failure among high-risk patients after extubation. Trial registration UMIN-CTR UMIN000039459. Registered February 11, 2020.

Keywords: Blood gas analysis; End-tidal partial pressure of carbon dioxide; Mainstream capnography; Noninvasive ventilation; Partial pressure of carbon dioxide; Post-extubation.