Clinical Decision Making in the ICU: Dysphagia Screening, Assessment, and Treatment.

Clinicians often perceive the intensive care unit as among the most intimidating environments in patient care. With the proper training, acquisition of skill, and approach to clinical care, feelings of intimidation may be overcome with the great rewards this level of care has to offer. This review-spanning the ages of birth to senescence and covering oral/nasal endotracheal intubation and tracheostomy-presents a clinically relevant, directly applicable review of screening, assessment, and treatment of dysphagia in the patients who are critically ill for clinical speech-language pathologists and identifies gaps in the clinical peer-reviewed literature for researchers.

Subclinical dysphagia in persons with Prader-Willi syndrome.

Prader-Willi Syndrome (PWS) is caused by a genetic imprinting abnormality resulting from the lack of expression of the paternal genes at 15q11-q13. Intellectual disability, low muscle tone, and life-threatening hyperphagia are hallmarks of the phenotype. The need for the Heimlich maneuver, death from choking, and pulmonary infection occur in a disproportionally high number of persons with PWS. The widely held belief is that eating behaviors are responsible for choking and aspiration; yet, no investigation had sought to determine if swallowing impairments were present in persons with PWS. To address this research and clinical gap, simultaneous videofluoroscopy and nasal respiratory signals were used to record swallowing function and breathing/swallowing coordination in 30 participants with PWS. Subjects consumed thin liquid and barium cookies under two randomized conditions as follows: (i) controlled (cues to swallow and standardized bolus sizes); (ii) spontaneous (no cues or bolus size control). Under videofluoroscopy, the cohort showed disordered pharyngeal and esophageal swallowing in both conditions with disturbances in timing, clearance, and coordination of swallowing with the respiratory cycle. No participant showed a sensory response such as attempting to clear residue or coughing; thereby supporting the lack of overt symptoms. We conclude that the high death rate from choking and pulmonary infection in children and adults with PWS may be related, in part, to underlying, asymptomatic dysphagia. The combination of rapid eating and dysphagia would increase the risk of aspiration-related morbidity and mortality. © 2016 Wiley Periodicals, Inc.

Breathing and Swallowing: The Next Frontier.

The anatomical overlap of the pathways for air passage and nutrition necessitate precise coordination between the two vital functions. Neuroanatomic structures in the brainstem for sucking, breathing, and swallowing are also in close proximity and must swiftly coordinate the processes. In a healthy neonate, the oropharyngeal experience and stimulation of early feeding enables respiratory control during suckling to develop. Despite wide variability among the methods used to investigate breathing and swallowing coordination in infancy, a consistent finding of postswallow exhalation has been reported. Postswallow exhalation is significant because the positive airflow of exhalation is believed to provide airway clearance. Preterm neonates and infants swallow during all phases of the respiratory cycle, but ultimately progress to the most commonly reported pattern, which is inhale-swallow-exhale. This pattern is similar to the adult pattern of exhale-swallow-exhale. Monitoring respiratory signals during nonnutritive sucking and early feeding may help to identify newborns with increased risk of aspiration and assist with clinical decision making.

Deglutitive subglottic air pressure and respiratory system recoil.

The purpose of this experiment was to confirm the presence of positive subglottic air pressure during swallowing, known as deglutitive subglottic air pressure (DPsub), in a group of healthy individuals. We also sought to determine if respiratory system recoil is responsible for generating the pressure. Ten healthy volunteers underwent direct DPsub measurement via percutaneous puncture of the cricothyroid membrane. Simultaneous DPsub and nasal airflow volumes were recorded while participants swallowed calibrated boluses over a wide range of lung volumes. Body plethysmography was used to determine functional residual capacity and residual volume. A custom respiratory recoil measurement system was used to measure recoil pressures. Regression analysis of lung volume on DPsub and lung volume on recoil pressure yielded strong linear relationships (P < 0.0001, R (2) = 0.71 and P < 0.0001, R (2) = 0.69, respectively). A mixed-model analysis of the effect of method (direct puncture or recoil) on pressure showed that there was no effect (F = 0.63; P = 0.43). By confirming the presence of DPsub in healthy adults and showing that respiratory system recoil is the most likely mechanism that generates DPsub, treatment of persons with dysphagia has even greater potential to be expanded to include consideration of factors that affect respiratory control and recoil forces.

The coordination of breathing and swallowing in chronic obstructive pulmonary disease.

RATIONALE: During deglutition, a strongly preferred exhale-swallow-exhale pattern has been shown in healthy adults. Disruption of this pattern can provoke prandial aspiration. Impaired coordination of breathing and swallowing has been measured in patients with chronic obstructive pulmonary disease (COPD) during the exacerbated state, but no reports describe the coordination of breathing and swallowing in stable patients with COPD during oral intake. OBJECTIVES: To test the hypothesis that persons with moderate to severe COPD would show disordered coordination of breathing and swallowing during oral intake when compared with a matched, healthy control group. METHODS: This study used a prospective, repeated measures design using 25 subjects with COPD and 25 control subjects. Respiratory inductance plethysmography and nasal thermistry were used simultaneously to track respiratory signals. Submental surface EMG was used to mark the presence of each swallow within the respiratory cycle. Data were recorded while participants randomly and spontaneously swallowed solids and semi-solids. MEASUREMENTS AND MAIN RESULTS: Logistic regression showed that participants with COPD swallowed solid food during inhalation more frequently than normal subjects (P = 0.002) and had a significantly higher rate of inhaling after swallowing semi-solid material (P < 0.001). Subjects with COPD also swallowed pudding at low Vt significantly more often than they did the cookie (P = 0.006). Conversely, the control subjects swallowed cookie at low Vt significantly more often than pudding (P = 0.034). Significant differences in deglutitive apnea durations were also found. CONCLUSIONS: Patients with COPD exhibit disrupted coordination of the respiratory cycle with deglutition. Disrupted breathing-swallowing coordination could increase the risk of aspiration in patients with advanced COPD and may contribute to exacerbations.

Direct measurement of subglottic air pressure while swallowing.

OBJECTIVE: The subglottic pressure theory for swallowing asserts that laryngeal mechanoreceptors have a role in the regulation of swallowing function. The primary purpose of this study was to determine if subglottic air pressure is generated during swallowing in a healthy, nontracheostomized person. METHODS: This pilot investigation used a prospective, repeated-measures design in a single subject. Direct measurement of subglottic air pressure was obtained through percutaneous puncture of the cricothyroid membrane. Swallows were timed with four randomly assigned lung volumes: total lung capacity, tidal volume, functional residual capacity (FRC), and residual volume. RESULTS: Lung volumes above FRC generated positive subglottic pressure during the swallow, whereas lung volumes below FRC generated consistently negative subglottic pressures. The degree and polarity of the pressure was directly related to lung volume at the time of the swallow. CONCLUSION: These findings illustrate that during normal swallowing, positive subglottic air pressure is likely present. Previously, subglottic air pressure during swallowing had been measured in tracheostomy patients only.

Lung volume effects on pharyngeal swallowing physiology.

The experiment was a prospective, repeated-measures design intended to determine how the variation of lung volume affects specific measures of swallowing physiology. Swallows were recorded in 28 healthy subjects, who ranged in age from 21 to 40 yr (mean age of 29 yr), by using simultaneous videofluoroscopy, bipolar intramuscular electromyography, and respiratory inductance plethysmography. Each subject swallowed three standardized pudding-like consistency boluses at three randomized lung volumes: total lung capacity, functional residual capacity, and residual volume. The results showed that pharyngeal activity duration of deglutition for swallows produced at residual volume was significantly longer than those occurring at total lung capacity or at functional residual capacity. No significant differences were found for bolus transit time or intramuscular electromyography of the superior constrictor. The results of this experiment lend support to the hypothesis that the respiratory system may have a regulatory function related to swallowing and that positive subglottic air pressure may be important for swallowing integrity. Eventually, new treatment paradigms for oropharyngeal dysphagia that are based on respiratory physiology may be developed.

Physiologic effects of open and closed tracheostomy tubes on the pharyngeal swallow.

Studies linking aspiration and dysphagia to an open tracheostomy tube exemplify the possibility that the larynx may have an influence on oropharyngeal swallow function. Experiments addressing the effects of tracheostomy tube occlusion during the swallow have looked at the presence and severity of aspiration, but few have included measurements that capture the changes in swallowing physiology. Also, hypotheses for the importance of near-normal subglottic air pressure during the swallow have not been offered to date. As such, the aim of this study was to compare the depth of laryngeal penetration, bolus speed, and duration of pharyngeal muscle contraction during the swallow in individuals with tracheostomy tubes while their tubes were open and closed. The results of this series of experiments indicate that within the same tracheostomized patient, pharyngeal swallowing physiology is measurably different in the absence of subglottic air pressure (open tube) as compared to the closed tube condition.

The coordination of breathing and swallowing in Parkinson's disease.

Multiple investigations have determined that healthy adults swallow most often during exhalation and that exhalation regularly follows the swallow, even when a swallow occurs during inhalation. We hypothesized that persons with idiopathic Parkinson's disease would demonstrate impaired breathing and swallowing coordination during spontaneous eating. Twenty-five healthy volunteers and 25 Parkinson's disease patients spontaneously swallowed calibrated pudding and cookie portions while simultaneous nasal airflow and respiratory inductance plethysmography were used to track spontaneous breathing. Surface EMG was used to record the timing of each swallow within the respiratory cycle. When compared to the healthy control group, those with Parkinson's disease swallowed significantly more often during inhalation and at low tidal volumes. The Parkinson's participants also exhibited significantly more postswallow inhalation for both consistencies. Only the healthy subjects exhibited significantly longer deglutitive apnea when swallows that occurred during inhalation were compared with those that occurred during exhalation. The high incidence of oropharyngeal dysphagia and risk of aspiration pneumonia found in Parkinson's disease patients may be partially attributable to impaired coordination of breathing and swallowing.