Clinical Characteristics and Outcomes of COVID-19 Acute Respiratory Distress Syndrome Patients Requiring Invasive Mechanical Ventilation in a Lower Middle-Income Country

Optimizing the connection of CRRT and ECMO lines with additional pressure regulator on the therapeutic effect, filter life, and incidence of complications

BACKGROUND

Extracorporeal membrane oxygenation (ECMO) is used for severe cardiopulmonary failure, with veno-arterial ECMO for cardiogenic shock and veno-venous ECMO for acute respiratory failure. ECMO's application has expanded to ICUs, emergency departments, and operating rooms. ECMO patients are at high risk for complications, including acute kidney injury (AKI), often requiring renal replacement therapy (RRT), posing significant management challenges.

METHODS

From August 2015 to June 2022, 120 patients were cured with veno-venous ECMO (n = 60) or veno-arterial ECMO (VA-ECMO, n = 60) combined with CRRT in our hospital. In the control group (n = 60), the input end (arterial end) of CRRT was connected to the ECMO oxygenator. The reinfusion end (venous end) of CRRT was connected to the oxygenator of ECMO for CRRT + ECMO treatment. In the experimental group (n = 60), the input end (arterial end) of CRRT was connected to the oxygenator of ECMO, and an additional pressure regulating device was installed on the connection of the 2 lines. The observation indexes including clinical therapeutic effect, clinical therapeutic effect, the incidence of complications, and the incidence of complications were compared.

RESULTS

There was a notable decrease in serum creatinine, and the differences in blood urea nitrogen, procalcitonin, and C-reactive protein after operation were statistically significant (P < .05). The filter use time in the study group was notably longer (P < .01). There exhibited no remarkable difference in the incidences of bleeding, thrombosis, numbness of hands and feet, metabolic alkalosis, disseminated intravascular coagulation, organ dysfunction syndrome, hyperbilirubinemia, and infection.

CONCLUSION

This study demonstrates that additional pressure regulation devices are installed at the line connection between the CRRT input end and the CRRT return end to ensure that the flow rate of ECMO does not affect the CRRT treatment. ECMO and CRRT provide a safe pressure range so that the ECMO line can be safely connected to the CRRT machine at physiological pressure, reducing the occurrence of complications related to CRRT machine interruption and improving the efficiency of CRRT without affecting the efficiency of ECMO, ensuring patient safety.

Cytokine Levels and Severity of Illness Scoring Systems to Predict Mortality in COVID-19 Infection

Various scoring systems and cytokines have been cited as predicting disease severity in COVID-19 infection. This study analyzed the link between mortality rate, levels of cytokines, and scoring systems such as the Glasgow Coma Scale (GCS), Acute Physiologic Assessment and Chronic Health Evaluation II (APACHE II), Sequential Organ Failure Assessment (SOFA), and Charlson Comorbidity Index in patients infected with COVID-19. Adult patients infected with COVID-19 were followed up in the intensive care unit (ICU) and analyzed prospectively. We measured serum cytokine levels (Interleukin-10 (IL-10), Interleukin-8 (IL-8), Interleukin-6 (IL-6), Interleukin-1β (IL-1β), tumor necrosis factor-alpha (TNF-α) and High mobility group box 1 (HMGB-1)) and recorded GCS, APACHE II, SOFA, and Charlson comorbidity index scores on admission to the ICU. Receiver operating curve (ROC) analysis was performed to predict mortality from IL-1β, IL-6 IL-10, IL-8, TNF-α, and HMGB-1 values. Study participants were grouped as follows: Group A, survivors, and Group B, deceased, during the 28-day follow-up. The mean age was 65.69 (±13.56) in Group A (n = 36) and 70.85 (±10.06) in Group B (n = 27). The female/male ratio was 23/40. Age, sex, body mass index (BMI), comorbid illnesses, GCS, APACHE II, SOFA, and Charlson scores, duration of hospitalization or ICU admission, therapeutic choices, and lymphocyte, PMNL, NLR, platelet, D-dimer, fibrinogen, GGT, CRP, procalcitonin, and lactate levels were similar between the groups. The frequency of acute kidney injury (AKI) was higher in Group B (p = 0.005). Serum IL-10, IL-8, IL-6, IL-1β, TNF-α, HMGB-1, ferritin, and LDH values were higher, and PaO₂/FiO₂ was lower in Group B than in Group A. ROC analysis showed that there was an association between serum IL-1β (>1015.7), serum IL-6 (>116.7), serum IL-8 (>258.4), serum IL-10 (>247.5), serum TNF-α (>280.7), and serum HMGB-1 (>23.5) and mortality. AKI gave rise to a greater risk of mortality (odds ratio: 7.081, p = 0.014). Mortality was associated with serum IL-10, IL-8, IL-6, IL-1β, TNF-α, and HMGB-1 but not with GCS, APACHE II, SOFA, or Charlson comorbidity index scores. AKI increased the risk of mortality by seven times. Our findings suggest that cytokine levels (serum IL-10, IL-8, IL-6, IL-1β, TNF-α, and HMGB-1) were predictors of mortality in COVID-19 infection. In addition, our results might give an opinion about the course of COVID-19 infection.

Unilateral acute lung injury in pig: a promising animal model

Background

Acute lung injury (ALI) occurs in 23% unilateral. Models of unilateral ALI were developed and used previously without clearly demonstrating the strictly unilateral nature and severity of lung injury by the key parameters characterizing ALI as defined by the American Thoracic Society (ATS). Thus, the use of unilateral ALI remained rare despite the innovative approach. Therefore, we developed a unilateral model of ALI and focused on the crucial parameters characterizing ALI. This model can serve for direct comparisons between the injured and intact lungs within single animals, thus, reducing the number of animals required for valid experimental conclusions.

Methods

We established the model in nine pigs, followed by an evaluation of key parameters in six pigs (main study). Pigs were ventilated using an adapted left double-lumen tube for lung separation and two ventilators. ALI was induced in the left lung with cyclic rinsing (NaCl 0.9% + Triton® X-100), after which pigs were ventilated for different time spans to test for the timing of ALI onset. Ventilatory and metabolic parameters were evaluated, and bronchoalveolar lavage (BAL) was performed for measurements of inflammatory mediators. Finally, histopathological specimens were collected and examined in respect of characteristics defining the lung injury score (LIS) as suggested by the ATS.

Results

After adjustments of the model (n = 9) we were able to induce strictly left unilateral ALI in all six pigs of the evaluation study. The median lung injury score was 0.72 (IQR 0.62–0.79) in the left lung vs 0.14 (IQR 0.14–0.16; p < 0.05) in the right lung, confirming unilateral ALI. A significant and sustained drop in pulmonary compliance (Cdyn) of the left lung occurred immediately, whereas Cdyn of the right lung remained unchanged (p < 0.05). BAL fluid concentrations of interleukin-6 and -8 were increased in both lungs.

Conclusions

We established a model of unilateral ALI in pigs, confirmed by histopathology, and typical changes in respiratory mechanics and an inflammatory response. This thoroughly evaluated model could serve as a basis for future studies and for comparing pathophysiological and pharmacological changes in the uninjured and injured lung within the same animal.