Cough response to aspiration in thin and thick fluids during FEES in hospitalized inpatients

The modifications of fluid viscosity and/or volume are common strategies in dysphagia management, with increased viscosity or reduced volume intended to reduce aspiration. Little attention has been given to whether cough response to aspiration varies across different viscosities and volumes.

This prospective observational study investigated aspiration prevalence and cough response to aspiration in thin and thick fluids of two different volumes in patients referred for flexible endoscopic evaluation of swallowing (FEES) in an acute hospital setting.

Consecutive inpatients (N = 180) referred for FEES were recruited: stroke 51 (28%); other neurological condition (traumatic brain injury, progressive neurological) 33 (18%); cardiovascular critical care 51 (28%); respiratory illness/condition 23 (13%); spinal injury 9 (5%); and other 13 (7%). A standardized protocol was completed on 268 FEES (180 first FEES, 88 repeat FEES). Penetration-aspiration scale (PAS) scores were obtained for thin and mildly thick fluids at two volumes: 5 ml teaspoon and 50 ml continuous drinking.

The incidence of aspiration (PAS > 5) was 32% for thin fluids and 18% for thick fluids. There was a significant association between cough response to aspiration and viscosity (p < .001) and volume (p < .001). There was a higher prevalence of silent aspiration in thick fluids than thin fluids. Some patients demonstrated variable cough responsiveness to aspiration across different viscosities and volumes. With 5 ml volumes, 20 patients coughed when they aspirated thin fluids but silently aspirated thick fluids. In comparison, discrepancies in the 50 ml volume were fewer, with three patients coughing when they aspirated thin fluids but silently aspirating thick fluids.

Cough response to aspiration differs across bolus volumes and viscosities. The finding of inconsistent cough response to aspiration in some patients strongly encourages the use of instrumental assessment to guide decisions regarding diet modifications.