RESUMO
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 (Crs). 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 Crs at lower PEEP (- 0.057, P = 0.75; and rho = 0.15, P = 0.41, respectively). On the contrary, the ratio of Crs at higher PEEP to Crs at lower PEEP (Crs 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 Crs ratio (higher/lower). Therefore, NMD and R/I ratio could be potential indicators of recruitability that can be performed at the bedside.
RESUMO
Background: In patients with severe coronavirus disease (COVID-19), the use of acrylonitrile hemofilters can reduce cytokine concentrations. However, acrylonitrile hemofilters can easily coagulate, and the effect of hemofilters on improvement in patient prognosis remains unclear. Therefore, we aimed to investigate the changes in serum cytokine concentrations, alleviation of organ damage, and improvement in patient prognosis with continuous renal replacement therapy (CRRT) using a cellulose triacetate (CTA) filter with excellent anticoagulation property in patients with severe COVID-19. Methods: This was a retrospective, single-center study conducted by the Advanced Critical Care Center in Sapporo Medical University Hospital, Japan. Seven patients with severe COVID-19 between March 01 and June 30, 2020, were included. The patients were under mechanical ventilation and received continuous blood purification therapy with a CTA filter. We summarized the CRRT status and patient prognosis and measured their serum cytokine (interleukin [IL]-1ß, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor-α, and interferon-γ) and serum marker levels, before and after CRRT. In addition, we evaluated the changes in their respiratory status, hemodynamics, and organ dysfunction scores. The average age of the patients was 61.5 years, and five patients were male. Extracorporeal membrane oxygenation was used in five patients. The treatment outcome included three deaths. Results: The median CRRT duration was 7 days. The hemofilter was replaced once a day. After CRRT, the IL-6 concentration decreased from 393 to 85 pg/mL (p = 0.016), the Krebs von den Lungen-6 concentration decreased from 554 to 350 U/mL, and the PaO2/FiO2 ratio increased significantly from 90 to 248, and therefore, oxygenation improved. In addition, the norepinephrine dose and lactate level decreased, and the circulation tended to improve; however, the renal function and Sequential Organ Failure Assessment score did not change. Conclusions: The serum IL-6 level decreased, and the respiratory status improved upon CRRT using a CTA filter in patients with severe COVID-19.
