Early Measurement of Quadriceps Response to Neuromuscular Electrical Stimulation to Identify Future ICU-Acquired Weakness.

OBJECTIVES

To evaluate whether early measurement of quadriceps response to neuromuscular electrical stimulation (NMES) on mechanically ventilated patients could predict future ICU-acquired weakness (ICU-AW).

DESIGN

Prospective observational study.

SETTING

Le Havre Hospital medico-surgical ICU.

PATIENTS: All mechanically ventilated patients (> 24 hr), with no prospect of extubation in the following 24 hours.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN

RESULTS

Eighty patients were enrolled in the study. Quadriceps response to NMES was measured using ultrasound and shear wave elastography (SWE) after 24 hours of mechanical ventilation, or on the day of neuromuscular blocker cessation if any (baseline). Stimulation intensity was adjusted to induce a quadriceps contraction causing knee extension (heel lifting). Changes in thickness (ultrasound) and stiffness (SWE) of the quadriceps during NMES were collected. An Medical Research Council sum score less than 48 within 24 hours of extubation diagnosed ICU-acquired weakness. A predictive model A, based on the quadriceps response to NMES at baseline, was compared with a model B, derived from identified risk factors, and a combined model (A + B). Of the 80 individuals, 39 (49%) developed ICU-AW. Time delay between intubation and baseline was 3.0 days, and between baseline and extubation was 7.5 days. Stimulation intensity at baseline showed an area under the curve (AUC) of 0.77, with a higher intensity required in individuals who developed ICU-AW (+21.6 mA; p < 0.001). Quadriceps thickness and stiffness during NMES at baseline were 3.83 ± 2.35 cm and 102.76 ± 74.1 kPa, respectively. Model A reached an AUC of 0.87 (95% CI, 0.79-0.95), which was not statistically different from model B. The combined model had the largest AUC (0.94; 95% CI, 0.89-0.99).

CONCLUSIONS

A model based on the quadriceps response to NMES after 24 hours of mechanical ventilation, or on the day of neuromuscular blocker cessation seems promising to anticipate future ICU-AW.