The assessment of intensive care unit-acquired weakness in adult patients at risk of post intensive care syndrome

Abstract

Intensive care unit-acquired weakness (ICUAW) is a syndrome of generalised neuromuscular weakness that develops in critically ill patients for which there is no alternative explanation other than the critical illness itself, and which has a prevalence of 25% to 80% in ICU survivors. The diagnosis and grading of ICUAW is made by excluding other causes of neuromuscular weakness and by repetitive clinical examination of muscle strength using the Medical Research Council Sum-Score (MRC-SS). The aim of the study was to evaluate ICUAW, and diagnostic methods available for this condition, in ICU survivors at risk of post intensive care syndrome (PICS) in a South African tertiary public sector hospital. METHODOLOGY: A prospective, single-centre observational study was conducted in a multi-disciplinary tertiary ICU in Eastern Cape. Patients at risk for post intensive care syndrome were included in the study. Patients were evaluated for ICUAW at six weeks and six months post-hospitalisation with the MRC-SS and handheld dynamometry (HDD). Full criteria ICUAW is defined as an MRC-SS of less than 48 out of 60. RESULTS: We enrolled 150 patients in the study, of which 103 patients completed the six month follow-up. At six weeks and six months, respectively, 3 and 2 patients’ MRC SS were less than 48/60. The median MRC-SS was 58/60 (IQR: 52-60) at six weeks and 60/60 (IQR: 58-60) at six months. There was an average change of 32,75% in the mean force from six weeks to six months for all muscle actions on both sides, with p < 0.001 indicating a significant difference. Fair correlations (r = 03-0.5) were observed between the MRC scale and HHD measurements for each muscle action from six weeks to six months. The correlation between the MRC scale and HHD proved to be significant (p < 0.001). CONCLUSION: There is a low incidence of the full criteria of ICUAW in relatively young and previously healthy ICU survivors at risk for PICS. Both the MRC-sum scores and HHD measurements showed a significant improvement over six months and there was an acceptable correlation between them. The findings of this study indicate that the strength assessed by both methods is related and tends to change in a similar direction over time.