Intensive care unit–acquired weakness: unanswered questions and targets for future research

Simone Piva,Nazzareno Fagoni,Nicola Latronico

doi:10.12688/f1000research.17376.1

Simone Piva, Nazzareno Fagoni + Show 1 more

Open Access

https://doi.org/10.12688/f1000research.17376.1

Copy DOI

Journal: F1000Research	Publication Date: Apr 17, 2019
Citations: 73	License type: CC BY 4.0

Affiliation: University of Brescia

Abstract

Intensive care unit–acquired weakness (ICU-AW) is the most common neuromuscular impairment in critically ill patients. We discuss critical aspects of ICU-AW that have not been completely defined or that are still under discussion. Critical illness polyneuropathy, myopathy, and muscle atrophy contribute in various proportions to ICU-AW. Diagnosis of ICU-AW is clinical and is based on Medical Research Council sum score and handgrip dynamometry for limb weakness and recognition of a patient’s ventilator dependency or difficult weaning from artificial ventilation for diaphragmatic weakness (DW). ICU-AW can be caused by a critical illness polyneuropathy, a critical illness myopathy, or muscle disuse atrophy, alone or in combination. Its diagnosis requires both clinical assessment of muscle strength and complete electrophysiological evaluation of peripheral nerves and muscles. The peroneal nerve test (PENT) is a quick simplified electrophysiological test with high sensitivity and good specificity that can be used instead of complete electrophysiological evaluation as a screening test in non-cooperative patients. DW, assessed by bilateral phrenic nerve magnetic stimulation or diaphragm ultrasound, can be an isolated event without concurrent limb muscle involvement. Therefore, it remains uncertain whether DW and limb weakness are different manifestations of the same syndrome or are two distinct entities. Delirium is often associated with ICU-AW but a clear correlation between these two entities requires further studies. Artificial nutrition may have an impact on ICU-AW, but no study has assessed the impact of nutrition on ICU-AW as the primary outcome. Early mobilization improves activity limitation at hospital discharge if it is started early in the ICU, but beneficial long-term effects are not established. Determinants of ICU-AW can be many and can interact with each other. Therefore, future studies assessing early mobilization should consider a holistic patient approach with consideration of all components that may lead to muscle weakness.

Highlights

Intensive care unit–acquired weakness (ICU-AW), defined as “clinically detected weakness in critically ill patients in whom there is no plausible etiology other than critical illness”[1], is the most common neuromuscular impairment and it affects the clinical course and outcomes of ICU patients[2]
ICU-AW can be ascribed to a critical illness polyneuropathy (CIP), a critical illness myopathy (CIM), or severe muscle disuse atrophy
Conclusions and Future directions ICU-AW is a common complication in ICU patients and has a clinically relevant impact on short- and long-term outcomes

Summary

Introduction

Intensive care unit–acquired weakness (ICU-AW), defined as “clinically detected weakness in critically ill patients in whom there is no plausible etiology other than critical illness”[1], is the most common neuromuscular impairment and it affects the clinical course and outcomes of ICU patients[2]. In a large sub-study of 730 patients in the EPaNIC (Early Parenteral Nutrition Completing Enteral Nutrition in Adult Critically Ill Patients) trial, an abnormal motor nerve action potential amplitude measured at 8 days after ICU admission was independently associated with increased 1-year mortality[21]. With a prevalence rate ranging between 20 and 40%, delirium, hypoactive delirium, is associated with deleterious clinical outcomes, including prolonged mechanical ventilation, increased ICU and hospital LOS, increased mortality, and impaired cognitive function for up to 12 months after discharge[49,50,51] They are clearly distinct entities, delirium and ICU-AW are possibly related and may even interact negatively with each other[4]. A recent post-hoc analysis of a randomized controlled trial showed that early, goaldirected mobilization is not harmful in patients with impaired consciousness and might be effective in achieving higher mobility levels and better functional status at hospital discharge[82]

Conclusions and Future directions

Findings

PubMed Abstract