[Impact of extracorporeal carbon dioxide removal combined with continuous renal replacement therapy on diaphragmatic function in patients with acute respiratory distress syndrome].

OBJECTIVE: To investigate the effects of extracorporeal carbon dioxide removal (ECCO2 R) combined with continuous renal replacement therapy (CRRT) on respiratory efficiency and diaphragm function in patients with acute respiratory distress syndrome (ARDS) received mechanical ventilation.

METHODS: A prospective randomized controlled study was conducted. Sixty patients with mild to moderate ARDS admitted to the department of respiratory and critical care medicine of Henan Provincial People's Hospital from January 2019 to January 2021 were enrolled, and they were divided into observation group and control group according to the random number table method, with 30 cases in each group. All patients received antibiotics, anti-inflammatory, and mechanical ventilation therapy. On this basis, the observation group received ECCO2 R and CRRT, while the control group received bedside CRRT. Baseline data including gender, age, etiology, acute physiology and chronic health evaluation II (APACHE II), etc., were recorded. Arterial blood gas analysis [including arterial partial pressure of oxygen (PaO2 ), arterial partial pressure of carbon dioxide (PaCO2 ), and oxygenation index (PaO2 /FiO2 )] was performed at 12 hours and 24 hours during the treatment, and respiratory mechanics parameters [including tidal volume, respiratory rate, maximum expiratory pressure (MEP), and maximum inspiratory pressure (MIP)] were recorded, and rapid shallow breathing index (RSBI) was calculated. The levels of glutathione peroxidase (GSH-Px), malondialdehyde (MDA), and superoxide dismutase (SOD) in serum were detected by enzyme-linked immunosorbent assay (ELISA). Diaphragm thickness and diaphragm activity were measured by ultrasonography at 24 hours during the treatment.

RESULTS: There were no significantly differences in age, gender, etiology, and APACHE II score between the two groups, indicating that the baseline data of the two groups were balanced and comparable. Compared with the 12 hours after treatment, the PaO2 and PaO2 /FiO2 in the observation group significantly increased, PaCO2 significantly decreased, RSBI significantly decreased, MEP and MIP significantly increased, and serum GSH-Px and MDA significantly decreased, while SOD significantly increased at 24 hours during the treatment. In the control group, only PaCO2 significantly decreased. Compared with the control group, the PaCO2 significantly decreased in the observation group at 12 hours and 24 hours [mmHg (1 mmHg≈0.133 kPa): 55.05±7.57 vs. 59.49±6.95, 52.77±7.88 vs. 58.25±6.92, both P < 0.05], but no significantly differences in PaO2 and PaO2 /FiO2 . Compared with the control group, the observation group showed significant decreases in RSBI at 12 hours and 24 hours (times×min-1 ×L-1 : 85.92±8.83 vs. 90.38±3.78, 75.73±3.86 vs. 90.05±3.66, both P < 0.05), significant increases in MEP and MIP [MEP (mmH2 O, 1 mmH2 O≈0.01 kPa): 86.64±5.99 vs. 83.88±4.18, 93.70±5.59 vs. 85.04±3.73; MIP (mmH2 O): 44.19±6.66 vs. 41.17±3.13, 57.52±5.28 vs. 42.34±5.39, all P < 0.05], and significant decreases in serum GSH-Px and MDA [GSH-Px (mg/L): 78.52±8.72 vs. 82.10±3.37, 57.11±4.67 vs. 81.17±5.13; MDA (μmol/L): 7.84±1.97 vs. 8.71±0.83, 3.67±0.78 vs. 8.41±1.09, all P < 0.05], as well as a significant increase in SOD (U/L: 681.85±49.24 vs. 659.40±26.47, 782.32±40.56 vs. 676.65±51.97, both P < 0.05). Compared with the control group, the observation group showed significant increases in diaphragm thickness and diaphragm activity at 24 hours of treatment [diaphragm thickness (cm): 1.93±0.28 vs. 1.40±0.24, diaphragmatic thickening fraction: (0.22±0.04)% vs. (0.19±0.02)%, quiet breathing diaphragm displacement (cm): 1.42±0.13 vs. 1.36±0.06, deep breathing diaphragm displacement (cm): 5.11±0.75 vs. 2.64±0.59, all P < 0.05].

CONCLUSIONS: ECCO2 R combined with CRRT can reduce work of breathing and oxidative stress levels in ARDS patients receiving non-invasive ventilation, and protect diaphragm function.