SCCM Resource Library-Respiratory Muscle Wasting Is Associated With Mortality in ICU COVID-19 Patients

Video Transcription

I'm a current PGY-1 internal medicine resident at Brooke Armory Medical Center, Fort Sam Houston,  Texas. I have interest in pulmonary critical care fellowship and have research interest in sepsis outcomes, respiratory muscle dysfunction, and predictive modeling.  There are no relationships to disclose regarding the work conducted on this talk.  Severe COVID-19 infections are associated with high rates of ICU admission and need for mechanical ventilation. Some reports have stated that as high as 80-80% of those admitted  to an ICU with COVID require mechanical ventilation. Thus, there has been strong interest to predict outcomes of patients with severe COVID-19 given the extraordinary strain  on the healthcare system and the need for novel therapies to improve the high mortality rate  seen with this devastating disease. Currently, most predictive modeling, including the 4C mortality score for COVID-19 and the COVID-19 inpatient risk calculator, are beneficial in  risk stratifying and predicting inpatient mortality. However, most of these scores rely  solely on demographic and clinical variables. There is a need to find better risk stratification  models to predict outcomes in these patients. Sarcopenia, or the state of generalized muscle  wasting and dysfunction, has been demonstrated to be associated with poor outcomes across various  patient populations, including surgical, critical care, and oncologic. More recently, thoracic sarcopenia, or the skeletal muscle wasting at the thoracic vertebral level,  has emerged as a prognostic factor in certain patient populations that undergo CT chest imaging,  including those undergoing cardiothoracic surgery or those with respiratory disorders. For example,  Troeschel et al. demonstrated in 128 patients who underwent pneumonectomy that those with increased thoracic muscle assessed by CT imaging had improved overall long-term survival.  Similarly, Moon et al. demonstrated in 180 patients diagnosed with idiopathic pulmonary fibrosis that low thoracic muscle mass was a strong risk factor for all-cause mortality.  There is a lack of research investigating the role of thoracic sarcopenia in critical illness.  The aims of this study were, one, to implement a new technique to assess degree of respiratory muscle wasting through use of computed tomography and body composition analysis.  Aim two was to investigate the impact of respiratory muscle wasting as assessed by CT  imaging on the outcomes of patients with severe COVID-19 infection. Our hypothesis was respiratory  muscle wasting is associated with poor outcomes in patients with COVID-19 infection.  This was a retrospective single-center cohort study conducted between March 2020 and December 2020. Inclusion criteria included patients found to be COVID-positive at time of  primary infection requiring admission to the medical ICU and who had received at least a chest  CT scan within two days of admission. Exclusion criteria included patients transferred from  outside hospitals, patients who underwent ECMO, pregnancy, patients who underwent major surgery  during their stay, and presence of end-stage liver disease. Patients were stratified into  two groups for analysis, those with the lowest gender-specific quartile respiratory muscle index  and those with the second through fourth gender-specific quartiles of respiratory muscle index. Primary outcomes of inpatient mortality and secondary outcomes included duration of  mechanical ventilation, rates of tracheostomy, and length of stay. Respiratory muscle analysis  were conducted on cross-sectional slices of CT chest scans at the fifth thoracic vertebral level  as seen in the figure. Slice-o-matic software is utilized for all body composition analysis and was conducted by two separate readers who were trained in the software.  Respiratory muscle included the pectorals groups, serratus anterior, intercostal, subscapularis,  trapezius, and erector spinae muscles. Respiratory muscle index was then calculated by dividing each  individual's cross-sectional muscle area by their height in meters squared. Statistical analysis  was performed with Stata software. Overall, 99 patients met inclusion criteria with a medium BMI  of 30.3, ages 64 years, SOFA score of 4, and 67 percent were male. 19 patients comprised the  respiratory muscle wasting group. Those within the respiratory muscle wasting group were found  to be significantly older and with reduced BMI. Mean respiratory muscle index was 26.8 centimeters  squared by meters squared compared to 39.2 centimeters squared by meters squared in the  non-respiratory muscle wasting group. Presented here are basic COVID labs and treatments received by patients. Notably, patients were similar between groups regarding admission CRP,  ferritin, platelet, and LDH counts. Those in the respiratory muscle wasting group had significantly  decreased creatinine kinase levels. Otherwise, there was no difference in COVID-targeted  therapies received, namely that of corticosteroids or antiviral therapies such as remdesivir.  Regarding outcomes, there was no significant difference in rates of mechanical ventilation, duration of mechanical ventilation, rates of tracheostomy, or ICU length of stay between  groups. Those with respiratory muscle wasting were significantly associated with inpatient mortality  with a p-value of 0.019. On multivariate logistic regression, patients with respiratory muscle wasting were significantly associated with in-hospital mortality when adjusting for  admission platelet level. Odds ratio of 3.3, 95 percent confidence interval of 1.02 to 10.46,  and a p-value of 0.047. Overall, we demonstrated that respiratory muscle wasting is associated  with inpatient mortality in those admitted to a medical ICU for severe COVID-19 infections. Notable limitations include that this was a single-center retrospective study.  The patients included were somewhat heterogeneous regarding therapy received as not all underwent  mechanical ventilation. About 40 percent in this cohort received mechanical ventilation.  Finally, not all COVID-19 patients received CT chest scans early on admission. Thus, this may represent a cohort with increased concomitant thoracic processes such as pulmonary  embolism. The rate of pulmonary embolism in this cohort was relatively low at 10 percent.  Future directions include performing serial analysis of CT chest scans  over time in patients with mechanical ventilation dependence as a way to predict ventilator weaning.  Prospective studies are also needed to investigate the effects of various therapies, including respiratory muscle training and ventilation modes on the impact on ventilation  weaning success.

Video Summary

This study aimed to assess respiratory muscle wasting in patients with severe COVID-19 infection using computed tomography (CT) imaging and investigate its impact on patient outcomes. It was a retrospective single-center cohort study conducted between March 2020 and December 2020. The study found that respiratory muscle wasting was associated with increased inpatient mortality in patients admitted to the medical ICU for severe COVID-19 infections. However, there were no significant differences in rates of mechanical ventilation, duration of mechanical ventilation, rates of tracheostomy, or ICU length of stay between patients with and without respiratory muscle wasting. Further research is needed to explore the effects of respiratory muscle training and ventilation modes on weaning success in COVID-19 patients.

Asset Subtitle

Pulmonary, Infection, Worldwide Data, 2022

Asset Caption

INTRODUCTION: We previously reported an association between respiratory muscle wasting (RMW) and outcomes in patients requiring invasive mechanical ventilation (MV) for acute respiratory failure. We hypothesized that RMW is also associated with poor outcomes in patients with severe COVID-19 infection.
METHODS: After obtaining institutional review board approval, all patients admitted to the medical intensive care unit (ICU), between March 2020 and December 2020, with laboratory confirmed COVID-19 and received chest computed tomography (CT) were retrospectively identified. Exclusion criteria included outside hospital transfers, patients who underwent major surgery, were pregnant, < 18 years of age, or had end stage liver disease. Respiratory skeletal muscle cross-sectional area was assessed at the 5th thoracic vertebral level using Slice-O-Matic® software. The area was used to calculate respiratory muscle index (RMI). Patients were divided into two groups, 1) the lowest gender-specific quartile of RMI and 2) second-fourth gender-specific RMI quartiles for comparative analysis.
RESULTS: Overall, 99 patients met inclusion criteria with a median BMI of 30.3 kg/m2 (IQR 25.4-34.8), age of 64 years (IQR 51-74), ICU admission sequential organ failure assessment (SOFA) score of 4 (IQR 3-6), and 67% (67/99) were male. High-dose corticosteroids were administered as part of institutional COVID-19 protocol in 60% (59/99). Overall, 43% (43/99) required invasive mechanical ventilation and 31% (31/99) expired during hospitalization. On univariate analysis, presence of respiratory muscle wasting (p=0.019) and reduced ICU admission platelet count (p=0.001) were found to be associated with in-hospital mortality. There was no difference in mortality when comparing gender, medical comorbidities, SOFA score, inflammatory markers, neutrophil-to-lymphocyte ratio, or COVID-19 targeted therapies. On multivariate logistic regression, patients with respiratory muscle wasting were significantly associated with in-hospital mortality when adjusting for admission platelet level (OR 3.3, 95% CI 1.02-10.46, p=0.047).
CONCLUSION: Presence of RMW in patients with severe COVID-19 infection is associated with in-patient mortality. Knowledge of this can help guide future research and risk stratification of critically ill COVID-19 patients.

Meta Tag

Content Type Presentation

Knowledge Area Pulmonary

Knowledge Area Infection

Knowledge Area Worldwide Data

Knowledge Level Intermediate

Knowledge Level Advanced

Membership Level Select

Tag Respiratory Failure

Tag Epidemiology Outcomes

Tag Mortality

Tag COVID-19

Tag Mechanical Ventilation

Year 2022

Keywords

respiratory muscle wasting

severe COVID-19 infection

computed tomography imaging

patient outcomes

inpatient mortality

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