Assessment of Inspiratory Effort in Spontaneously Breathing COVID-19 ARDS Patients Undergoing Helmet CPAP: A Comparison between Esophageal, Transdiaphragmatic and Central Venous Pressure Swing

Abstract

Introduction: The clinical features of COVID-19 are highly variable. It has been speculated that the progression across COVID-19 may be triggered by excessive inspiratory drive activation. The aim of the present study was to assess whether the tidal swing in central venous pressure (ΔCVP) is a reliable estimate of inspiratory effort. Methods: Thirty critically ill patients with COVID-19 ARDS underwent a PEEP trial (0–5–10 cmH2O) during helmet CPAP. Esophageal (ΔPes) and transdiaphragmatic (ΔPdi) pressure swings were measured as indices of inspiratory effort. ΔCVP was assessed via a standard venous catheter. A low and a high inspiratory effort were defined as ΔPes ≤ 10 and >15 cmH2O, respectively. Results: During the PEEP trial, no significant changes in ΔPes (11 [6–16] vs. 11 [7–15] vs. 12 [8–16] cmH2O, p = 0.652) and in ΔCVP (12 [7–17] vs. 11.5 [7–16] vs. 11.5 [8–15] cmH2O, p = 0.918) were detected. ΔCVP was significantly associated with ΔPes (marginal R2 0.87, p < 0.001). ΔCVP recognized both low (AUC-ROC curve 0.89 [0.84–0.96]) and high inspiratory efforts (AUC-ROC curve 0.98 [0.96–1]). Conclusions: ΔCVP is an easily available a reliable surrogate of ΔPes and can detect a low or a high inspiratory effort. This study provides a useful bedside tool to monitor the inspiratory effort of spontaneously breathing COVID-19 patients.

Effects of CPAP and FiO2 on respiratory effort and lung stress in early COVID-19 pneumonia: a randomized, crossover study

“…While the inability of Helmet-CPAP to reduce dynamic stress was previously reported [ 6 , 15 , 16 ], and likely reflects low potential for lung recruitment in early COVID-19 pneumonia [ 13 , 14 ], the increase in esophageal swing is less intuitive. A possible explanation is that the Helmet added an inspiratory load by not maintaining its pressure throughout the respiratory cycle [ 25 , 26 ].…”

“…Interestingly, Menga et al reported an increasing trend in respiratory effort with Helmet-CPAP compared to high flow nasal oxygen, but airway pressure was not monitored [ 15 ]. Conversely, no other study investigating the effects of Helmet-CPAP on respiratory effort had a baseline esophageal swing available for comparison, as patients kept breathing through the Helmet even when CPAP was set at zero cmH 2 O [ 6 , 16 ].…”

“…Due to the physiological design of the study, and to the lack of comparable investigations at the time it was performed, a formal sample size was not calculated. Consistent with similar physiological studies [ 15 , 16 , 23 , 24 ], we aimed to recruit a convenience sample size of 30 patients and 7 healthy controls.…”

“…Indeed, the few prospective investigations available in early COVID-19 pneumonia have suggested that CPAP does not reduce respiratory effort, nor the total lung stress [ 6 , 15 , 16 ]. However, CPAP was not compared with lower degrees of respiratory support ( e.g.…”

Setting positive end-expiratory pressure: role in diaphragm-protective ventilation

“…Morais et al indeed found a decrease of respiratory effort at high PEEP, as mentioned before [29], as mentioned before. Additionally, in COVID-19-patients on helmet continuous airway pressure ventilation, respiratory effort – quantified with diaphragmatic pressure swings – decreased with increasing PEEP levels [31]. Lastly, in healthy volunteers receiving noninvasive ventilation, an increase in PEEP also resulted in a decrease of respiratory effort [32].…”