Discriminant Ability of the 3-Ounce Water Swallow Test to Detect Aspiration in Acute Postoperative Cardiac Surgical Patients

Abstract

Dysphagia is a common complication of cardiac surgery (CS) contributing to morbidity and mortality. Although early dysphagia detection is important, no current screening guidelines or validated tools exist in the cardiac intensive care setting. We therefore aimed to examine the discriminant ability of the 3-ounce water swallow test (3 oz. WST) to detect aspiration in acute postoperative CS patients. 196 postoperative CS patients were enrolled in this prospective single-center study. Participants completed the 3 oz. WST and a standardized Flexible Endoscopic Evaluation of Swallowing. Independent duplicate ratings of the penetration aspiration scale (PAS) were performed in a blinded fashion (100% agreement criteria). Receiver operating characteristic curve and area under the curve (AUC) analyses were performed with sensitivity, specificity, positive, and negative predictive values (PPV, NPV) derived. Fifty-four CS patients (28%) were confirmed aspirators (PAS ≥ 6), of whom 48% (n = 26) were silent aspirators (PAS = 8). Both the sensitivity and specificity of the 3 oz. WST to identify instrumentally confirmed aspiration was 63% (AUC: 0.63, 95% CI: 0.54, 0.72), and PPV was 39% and NPV 82%. The 3 oz. WST demonstrated fair discriminant ability to detect aspiration in acute postoperative CS patients. The high rate of silent aspiration may explain, in part, these findings given that the screening fail criteria include an overt cough response. In isolation, the 3 oz. WST does not represent a sensitive screen of aspiration in postoperative CS patients with a need to identify alternative screening tools for this setting.

Keywords: 3-ounce; Aspiration; Cardiac Surgery; Dysphagia; Screen; Swallow; Water Screen.