Correlation between the hysteresis of the pressure-volume curve and the recruitment-to-inflation ratio in patients with coronavirus disease 2019

Ryuichi Nakayama; Naofumi Bunya; Shinshu Katayama; Yuya Goto; Yusuke Iwamoto; Kenshiro Wada; Keishi Ogura; Naoya Yama; Shintaro Takatsuka; Masumi Kishimoto; Kanako Takahashi; Ryuichiro Kakizaki; Keigo Sawamoto; Shuji Uemura; Keisuke Harada; Eichi Narimatsu

doi:10.1186/s13613-022-01081-x

Correlation between the hysteresis of the pressure-volume curve and the recruitment-to-inflation ratio in patients with coronavirus disease 2019

Ann Intensive Care. 2022 Nov 12;12(1):106. doi: 10.1186/s13613-022-01081-x.

Authors

Affiliations

¹ Department of Emergency Medicine, Sapporo Medical University School of Medicine, South 1, West 16, 291, Minami 1-Jo Nishi 16-Chome, Chuo-Ku, Sapporo, Hokkaido, 060-8556, Japan. ryuichin.smu99@gmail.com.
² Department of Emergency Medicine, Sapporo Medical University School of Medicine, South 1, West 16, 291, Minami 1-Jo Nishi 16-Chome, Chuo-Ku, Sapporo, Hokkaido, 060-8556, Japan.
³ Division of Intensive Care, Department of Anesthesiology and Intensive Care Medicine, Jichi Medical University School of Medicine, Shimotsuke, Tochigi, 329-0498, Japan.
⁴ Department of Intensive Care Medicine, School of Medicine, Sapporo Medical University, Sapporo, Hokkaido, Japan.
⁵ Division of Radiology and Nuclear Medicine, Sapporo Medical University Hospital, Sapporo, Japan.
⁶ Department of Diagnostic Radiology, Sapporo Medical University School of Medicine, Sapporo, Japan.
⁷ Center for Medical Education, Sapporo Medical University, Sapporo, Japan.
⁸ Department of Clinical Engineering, Sapporo Medical University Hospital, Sapporo, Japan.

Abstract

Background: Since the response to lung recruitment varies greatly among patients receiving mechanical ventilation, lung recruitability should be assessed before recruitment maneuvers. The pressure-volume curve (PV curve) and recruitment-to-inflation ratio (R/I ratio) can be used bedside for evaluating lung recruitability and individualing positive end-expiratory pressure (PEEP). Lung tissue recruitment on computed tomography has been correlated with normalized maximal distance (NMD) of the quasi-static PV curve. NMD is the maximal distance between the inspiratory and expiratory limb of the PV curve normalized to the maximal volume. However, the relationship between the different parameters of hysteresis of the quasi-static PV curve and R/I ratio for recruitability is unknown.

Methods: We analyzed the data of 33 patients with severe coronavirus disease 2019 (COVID-19) who received invasive mechanical ventilation. Respiratory waveform data were collected from the ventilator using proprietary acquisition software. We examined the relationship of the R/I ratio, quasi-static PV curve items such as NMD, and respiratory system compliance (C_rs).

Results: The median R/I ratio was 0.90 [interquartile range (IQR), 0.70-1.15] and median NMD was 41.0 [IQR, 37.1-44.1]. The NMD correlated significantly with the R/I ratio (rho = 0.74, P < 0.001). Sub-analysis showed that the NMD and R/I ratio did not correlate with C_rs at lower PEEP (- 0.057, P = 0.75; and rho = 0.15, P = 0.41, respectively). On the contrary, the ratio of C_rs at higher PEEP to C_rs at lower PEEP (C_rs ratio (higher/lower)) moderately correlated with NMD and R/I ratio (rho = 0.64, P < 0.001; and rho = 0.67, P < 0.001, respectively).

Conclusions: NMD of the quasi-static PV curve and R/I ratio for recruitability assessment are highly correlated. In addition, NMD and R/I ratio correlated with the C_rs ratio (higher/lower). Therefore, NMD and R/I ratio could be potential indicators of recruitability that can be performed at the bedside.

Keywords: Coronavirus disease 2019; Mechanical ventilation; Respiratory distress syndrome.