Diagnostic accuracy of quantitative neuromuscular ultrasound for the diagnosis of intensive care unit-acquired weakness: a cross-sectional observational study

Abstract

BackgroundNeuromuscular ultrasound is a noninvasive investigation, which can be easily performed at the bedside on the ICU. A reduction in muscle thickness and increase in echo intensity over time have been described in ICU patients, but the relation to ICU-acquired weakness (ICU-AW) is unknown. We hypothesized that quantitative assessment of muscle and nerve parameters with ultrasound can differentiate between patients with and without ICU-AW. The aim of this cross-sectional study was to investigate the diagnostic accuracy of neuromuscular ultrasound for diagnosing ICU-AW.MethodsNewly admitted ICU patients, mechanically ventilated for at least 48 h, were included. As soon as patients were awake and attentive, an ultrasound was made of four muscles and two nerves (index test) and ICU-AW was evaluated using muscle strength testing (reference standard; ICU-AW defined as mean Medical Research Council score <4). Diagnostic accuracy of muscle thickness, echo intensity and homogeneity (echo intensity standard deviation) as well as nerve cross-sectional area, thickness and vascularization were evaluated with the area under the curve of the receiver operating characteristic curve (ROC–AUC). We also evaluated diagnostic accuracy of z-scores of muscle thickness, echo intensity and echo intensity standard deviation.ResultsSeventy-one patients were evaluated of whom 41 had ICU-AW. Ultrasound was done at a median of 7 days after admission in patients without ICU-AW and 9 days in patients with ICU-AW. Diagnostic accuracy of all muscle and nerve parameters was low. ROC–AUC ranged from 51.3 to 68.0% for muscle parameters and from 51.0 to 66.7% for nerve parameters.ConclusionNeuromuscular ultrasound does not discriminate between patients with and without ICU-AW at the time the patient awakens and is therefore not able to reliably diagnose ICU-AW in ICU patients relatively early in the disease course.Electronic supplementary materialThe online version of this article (doi:10.1186/s13613-017-0263-8) contains supplementary material, which is available to authorized users.

Changes in Quantitative Muscle Ultrasound for Diagnosis of Intensive Care Unit-Acquired Weakness in Critically Ill Patients

“…In contrast, muscle ultrasound is a non-invasive, painless, and commonly used bedside technique that is entirely independent of patient cooperation. It is hence of great signi cance for assessing and monitoring muscular waste in critically ill patients [13,21]. The present study con rmed that patients with ICU-AW had a signi cant reduction of muscle TH and CSA than those of patients without ICU-AW, especially in the lower extremities.…”

“…However, these studies did not test the possibility of discrimination value of the muscle parameters by ultrasound between patients with and without ICU-AW. Witteveen's study performed ultrasonographic TH of tibialis anterior muscle, BB muscle, exor carpi radialis muscle, and RF muscle thus nding that for these muscles, the diagnostic accuracy of muscle parameters was rather low with ROC-AUC ranging from 51.3 to 68.0% [21]. Nevertheless, the study failed to observe the changes in muscle parameters over time, and CSA which is considered as a crucial property for contraction and strength of muscle was not involved in the study [13].…”

Muscular Ultrasound, Syndecan-1 and Procalcitonin Serum Levels to Assess Intensive Care Unit-Acquired Weakness

“…The incidence rate of 53% of patients diagnosed with ICU-AW in our study was comparable to previous reports. 1,3,17,29 Difficulties to rapidly diagnose ICU-AW in a majority of sedated and mechanically ventilated critically ill patients, as confirmed in the present study, are of importance for ICU physicians. 2,17,30 Clinical evaluation of the critically ill by using the MRC-SS alone could not detect ICU-AW, particularly at the time of assessment 1.…”

“…15,16 In contrast, muscular ultrasound (MUS) is independent from patient cooperation and is a painless, non-invasive, and commonly available bedside technique with emerging relevance for the diagnosis and monitoring of neuromuscular disorders in critically ill patients. [15][16][17][18] Increased echogenicity of skeletal muscles was observed by MUS in ICU patients and was correlated with neuromuscular dysfunction. [19][20][21][22] The pathogenesis of increased muscle echogenicity is uncertain.…”

Acute effect of passive cycle-ergometry and functional electrical stimulation on nitrosative stress and inflammatory cytokines in mechanically ventilated critically ill patients: a randomized controlled trial

“…This dysfunction is associated with inflammatory deregulation that apparently contributes to the onset of myopathy. The mechanism of muscle loss due to immobility has not been fully clarified to date, and the synergism among oxidative and nitrosative stress, inflammatory cytokines, and immobility presumably causes or accelerates muscle atrophy (2).…”