OBJECTIVES: Frailty and sarcopenia are known risk factors for adverse liver transplant outcomes and mortality. We hypothesized that frailty or sarcopenia could identify the risk for common serious transplant-related adverse respiratory events. METHODS: For 107 patients (74 men, 33 women) transplanted over 1 year, we measured frailty with gait speed, chair stands, and Karnofsky Performance Scale (KPS) and sarcopenia with Skeletal Muscle Index on computed tomography at L3. We recorded the stress-tested cardiac double product as an index of cardiac work capacity. Outcomes included days of intubation, aspiration, clinical pneumonia, reintubation/tracheostomy, days to discharge, and survival. We modeled the outcomes using unadjusted regression and multivariable analyses controlled for (i) age, sex, and either Model for End-Stage Liver Disease-Na (MELDNa) or Child–Turcotte–Pugh scores, (ii) hepatocellular carcinoma status, and (iii) chronic obstructive pulmonary disease and smoking history. Subgroup analysis was performed for living donor liver transplant and deceased donor liver transplant recipients. RESULTS: Gait speed was negatively associated with aspiration and pulmonary infection, both in unadjusted and MELDNa-adjusted models (adjusted odds ratio for aspiration 0.10 [95% confidence interval [CI] 0.02–0.67] and adjusted odds ratio for pulmonary infection 0.12 [95% CI 0.02–0.75]). Unadjusted and MELDNa-adjusted models for gait speed (coefficient −1.47, 95% CI −2.39 to −0.56) and KPS (coefficient −3.17, 95% CI −5.02 to −1.32) were significantly associated with shorter intubation times. No test was associated with length of stay or need for either reintubation or tracheostomy. DISCUSSION: Slow gait speed, an index of general frailty, indicates significant risk for post-transplant respiratory complications. Intervention to arrest or reverse frailty merits exploration as a potentially modifiable risk factor for improving transplant respiratory outcomes.

Objective: Dysphagia management relies on the evaluation of the temporospatial kinematic events of swallowing performed in videofluoroscopy (VF) by trained clinicians. The upper esophageal sphincter (UES) opening distension represents one of the important kinematic events that contribute to healthy swallowing. Insufficient distension of UES opening can lead to an accumulation of pharyngeal residue and subsequent aspiration which in turn can lead to adverse outcomes such as pneumonia. VF is usually used for the temporal and spatial evaluation of the UES opening; however, VF is not available in all clinical settings and may be inappropriate or undesirable for some patients. High resolution cervical auscultation (HRCA) is a noninvasive technology that uses neck-attached sensors and machine learning to characterize swallowing physiology by analyzing the swallow-induced vibrations/sounds in the anterior neck region. We investigated the ability of HRCA to noninvasively estimate the maximal distension of anterior-posterior (A-P) UES opening as accurately as the measurements performed by human judges from VF images. Methods and procedures: Trained judges performed the kinematic measurement of UES opening duration and A-P UES opening maximal distension on 434 swallows collected from 133 patients. We used a hybrid convolutional recurrent neural network supported by attention mechanisms which takes HRCA raw signals as input and estimates the value of the A-P UES opening maximal distension as output. Results: The proposed network estimated the A-P UES opening maximal distension with an absolute percentage error of 30% or less for more than 64.14% of the swallows in the dataset. Conclusion: This study provides substantial evidence for the feasibility of using HRCA to estimate one of the key spatial kinematic measurements used for dysphagia characterization and management. Clinical and Translational Impact Statement: The findings in this study have a direct impact on dysphagia diagnosis and management through providing a non-invasive and cheap way to estimate one of the most important swallowing kinematics, the UES opening distension, that contributes to safe swallowing. This study, along with other studies that utilize HRCA for swallowing kinematic analysis, paves the way for developing a widely available and easy-to-use tool for dysphagia diagnosis and management.

Dysphagia, commonly referred to as abnormal swallowing, affects millions of people annually. If not diagnosed expeditiously, dysphagia can lead to more severe complications, such as pneumonia, nutritional deficiency, and dehydration. Bedside screening is the first step of dysphagia characterization and is usually based on pass/fail tests in which a nurse observes the patient performing water swallows to look for dysphagia overt signs such as coughing. Though quick and convenient, bedside screening only provides low-level judgment of impairment, lacks standardization, and suffers from subjectivity. Recently, high resolution cervical auscultation (HRCA) has been investigated as a less expensive and non-invasive method to diagnose dysphagia. It has shown strong preliminary evidence of its effectiveness in penetration-aspiration detection as well as multiple swallow kinematics. HRCA signals have traditionally been collected and investigated in conjunction with videofluoroscopy exams which are performed using barium boluses including thin liquid. An HRCA-based bedside screening is highly desirable to expedite the initial dysphagia diagnosis and overcome all the drawbacks of the current pass/fail screening tests. However, all research conducted for using HRCA in dysphagia is based on thin liquid barium boluses and thus not guaranteed to provide valid results for water boluses used in bedside screening. If HRCA signals show no significant differences between water and thin liquid barium boluses, then the same algorithms developed on thin liquid barium boluses used in diagnostic imaging studies, it can be then directly used with water boluses. This study investigates the similarities and differences between HRCA signals from thin liquid barium swallows compared to those signals from water swallows. Multiple features from the time, frequency, time-frequency, and information-theoretic domain were extracted from each type of swallow and a group of linear mixed models was tested to determine the significance of differences. Machine learning classifiers were fit to the data as well to determine if the swallowed material (thin liquid barium or water) can be correctly predicted from an unlabeled set of HRCA signals. The results demonstrated that there is no systematic difference between the HRCA signals of thin liquid barium swallows and water swallows. While no systematic difference was discovered, the evidence of complete conformity between HRCA signals of both materials was inconclusive. These results must be validated further to confirm conformity between the HRCA signals of thin liquid barium swallows and water swallows.

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