Weakness as a complication of COVID-19 in critically ill patients: clinical features and prognostic factors in a case series

Introduction. Weakness is a frequent complication in those critically ill clue to COVID-19. This study describes its characteristics and the factors that can condition and predict it. Patients and methods. We conducted a prospective, descriptive, observational study of patients admitted to the intensive care unit (ICU) due to COVID-19 between April and May 2020 with muscle weakness. A motor balance equal to or lower than 3/5 according to the modified Medical Research Council muscle strength scale was considered to be severe clinical impairment. Altogether 25 analytical studies, 16 neurophysiological studies and one muscle biopsy were performed, with a telephone follow-up at one month, a comparative analysis between the groups with and without severe compromise, and determination of cut-off points for analytical parameters to predict severe involvement using ROC curves. Results. The sample consisted of 25 patients with a mean age of 58 years (standard deviation +/- 9). The median length of stay in the ICU was 27.5 days. All the electromyograms exhibited a myogenic pattern and 75% also showed neuropathy. The group with severe clinical involvement had higher levels of D-dimer (p = 0.08), lactate dehydrogenase (p = 0.03) and interleukin-6 (p = 0.10), and the combination of the alteration of any two of these three parameters predicted severe involvement with a sensitivity of 100% and a specificity of 76.9%. At one month of follow-up, 36% were unable to walk autonomously and 92% continued with muscle weakness. Conclusions. Weakness in severe COVID-19 patients has a major clinical impact. Its early detection and study by means of predictors of its development may allow for better management. The absence in some cases of classical risk factors for ICU-acquired weakness suggests a different pathophysiology.