Background: Prolonged mechanical ventilation is associated with muscle weakness, pharyngeal dysfunction, and symptomatic aspiration. The authors hypothesized that muscle strength measurements can be used to predict pharyngeal dysfunction (endoscopic evaluation-primary hypothesis), as well as symptomatic aspiration occurring during a 3-month follow-up period.
Methods: Thirty long-term ventilated patients admitted in two intensive care units at Massachusetts General Hospital were included. The authors conducted a fiberoptic endoscopic evaluation of swallowing and measured muscle strength using medical research council score within 24 h of each fiberoptic endoscopic evaluation of swallowing. A medical research council score less than 48 was considered clinically meaningful muscle weakness. A retrospective chart review was conducted to identify symptomatic aspiration events.
Results: Muscle weakness predicted pharyngeal dysfunction, defined as either valleculae and pyriform sinus residue scale of more than 1, or penetration aspiration scale of more than 1. Area under the curve of the receiver-operating curves for muscle strength (medical research council score) to predict pharyngeal, valleculae, and pyriform sinus residue scale of more than 1, penetration aspiration scale of more than 1, and symptomatic aspiration were 0.77 (95% CI, 0.63-0.97; P = 0.012), 0.79 (95% CI, 0.56-1; P = 0.02), and 0.74 (95% CI, 0.56-0.93; P = 0.02), respectively. Seventy percent of patients with muscle weakness showed symptomatic aspiration events. Muscle weakness was associated with an almost 10-fold increase in the symptomatic aspiration risk (odds ratio = 9.8; 95% CI, 1.6-60; P = 0.009).
Conclusion: In critically ill patients, muscle weakness is an independent predictor of pharyngeal dysfunction and symptomatic aspiration. Manual muscle strength testing may help identify patients at risk of symptomatic aspiration.