Assessment of dysphagia with the use of pulse oximetry

Comparative analysis of videofluoroscopy and pulse oximetry for aspiration identification in patients with dysphagia after stroke and non-dysphagics

PURPOSE

Dysphagia is a prevalent symptom observed in acute stroke. Several bedside screening tests are employed for the early detection of dysphagia. Pulse oximetry emerges as a practical and supportive method to augment the existing techniques utilized during bedside swallowing assessments. Desaturation levels, as measured by pulse oximetry, are acknowledged as indicative of aspiration by certain screening tests. However, the predictive capability of pulse oximetry in determining aspiration remains a subject of controversy. The objective of this study was to compare aspiration and oxygen desaturation levels by time and aspiration severity in dysphagic patients compared to healthy controls. It also aimed to evaluate the accuracy of pulse oximetry by comparing it with VFSS findings in detecting aspiration in both liquid (IDDSI-0) and semi-solid (IDDSI-4) consistencies.

MATERIALS AND METHODS

Eighty subjects (40 healthy and 40 acute stroke patients) participated. Patients suspected of dysphagia underwent videofluoroscopy as part of the stroke unit's routine procedure. Baseline SpO2 was measured before VFSS, and stabilized values were recorded. Sequential IDDSI-0 and IDDSI-4 barium tests were conducted with 5 ml boluses. Stabilized SPO2 values were recorded during swallowing and 3-min post-feeding. Patients with non-dysphagia received equal bolus monitoring. Changes in SPO2 during, before, and after swallowing were analyzed for each consistency in both groups.

RESULTS

The study revealed a statistically significant difference in SPO2 between patients with dysphagia and controls for IDDSI-4 and IDSSI-0. In IDDSI-4, 20% of patients experienced SpO2 decrease compared to 2.5% in control group (p = 0.013). For IDDSI-0, 35% of patients showed SpO2 decrease, while none in the control group did (p = 0.0001). Aspiration rates were 2.5% in IDDSI-4 and 57.5% in IDDSI-0. In IDDSI-0, SpO2 decrease significantly correlated with aspiration (p = 0.0001). In IDDSI-4, 20.5% had SpO2 decrease without aspiration, and showing no significant difference (p = 0.613). Penetration-Aspiration Scale scores had no significant association with SpO2 decrease (p = 0.602). Pulse oximetry in IDDSI-4 had limited sensitivity (0%) and positive predictive value, (0%) while in IDDSI-0, it demonstrated acceptable sensitivity (60.9%) and specificity (100%) with good discrimination capability (AUC = 0.83).

CONCLUSIONS

A decrease in SPO2 may indicate potential aspiration but is insufficient alone for detection. This study proposes pulse oximetry as a valuable complementary tool in assessing dysphagia but emphasizes that aspiration cannot be reliably predicted based solely on SpO2 decrease.

Contribution of Wireless Wi-Fi Intraoral Cameras to the Assessment of Swallowing Safety and Efficiency

BACKGROUND

Clinical evaluation of swallowing provides important clinical information but is limited in detecting penetration, aspiration, and pharyngeal residue in patients with suspected dysphagia. Although this is an old problem, there remains limited access to low-cost methods to evaluate swallowing safety and efficiency.

PURPOSE

The purpose of this technical report is to describe the experience of a single center that recently began using a wireless Wi-Fi intraoral camera for transoral endoscopic procedures as an adjunct to clinical swallowing evaluation. We describe the theoretical structure of this new clinical evaluation proposal. We present descriptive findings on its diagnostic performance in relation to videofluoroscopic swallowing study as the gold standard in a cohort of seven patients with dysphagia following head and neck cancer. We provide quantitative data on intra- and interrater reliability. Furthermore, this report discusses how this technology can be applied in the clinical practice of professionals who treat patients with dysphagia and provides directions for future research.

CONCLUSIONS

This preliminary retrospective study suggests that intraoral cameras can reveal the accumulated oropharyngeal secretions and postswallow pharyngolaryngeal residue in patients with suspected dysphagia. Future large-scale studies focusing on validating and exploring this contemporary low-cost technology as part of a clinical swallowing evaluation are warranted.

The Influence of Side-Lying Position on Oropharyngeal Swallow Function in At-Risk Infants: An Exploratory Study

This investigation assessed the effect of side-lying position on infant oropharyngeal swallow physiology. Infant modified barium swallow studies (MBS) recordings were retrospectively examined in matched-pairs comparing at-risk infants swallowing in both an upright/cradled position and a side-lying position. Swallow parameters were measured independently and through a consensus coding approach. Infants fed in side-lying position showed a decrease in airway invasion severity as compared with when those same infants were fed in an upright/cradled position (P = .009). Bolus location at the time of swallow initiation was higher when infants were fed in side-lying position as compared with cradle position (P = .024), representing decreased risk of airway invasion. Infants fed in side-lying position demonstrated fewer swallows per breaths (P = .032). This pilot study validates the need for additional research to further define the mechanisms related to this improvement, and to determine how diagnosis and medical stability moderate these findings.

An Investigation of Pulse Oximetry Levels during Swallowing in Healthy Adults and in Individuals with Severe and Very Severe Chronic Obstructive Pulmonary Disease

To compare pulse oximetry (PO) levels during swallowing in healthy adults and adults with severe chronic obstructive pulmonary disease (COPD). Participants included two groups of 60 healthy adults, balanced for gender. The young group ranged from 18 to 38 years, and the older group from 60 to 87 years. In addition, there were 11 participants with COPD aged 43 to 82 years. PO levels were collected as each participant swallowed 10 mL of water, 10 mL of applesauce, and a piece of diced pear (three trials each). Analyses for the healthy groups revealed neither statistically significant main effects for bolus type nor interactions between gender and age. For between-subject effects, there was no main effect for gender, but there was a large main effect for age, and a gender and age interaction. In the group with COPD, there were no significant differences across bolus types; however, PO measures were consistently lower than the healthy groups for all bolus types. Healthy adults exhibited stable PO levels across bolus types. Adults with COPD, although exhibiting significantly lower PO levels, also remained stable. For clinicians who monitor PO measures, these results offer a more comprehensive understanding of the nature of these measures during swallowing in these groups.

Dysphagia and its effects on swallowing sounds and vibrations in adults

BACKGROUND

To utilize cervical auscultation as a means of screening for risk of dysphagia, we must first determine how the signal differs between healthy subjects and subjects with swallowing disorders.

METHODS

In this experiment we gathered swallowing sound and vibration data from 53 (13 with stroke, 40 without) patients referred for imaging evaluation of swallowing function with videofluoroscopy. The analysis was limited to non-aspirating swallows of liquid with either thin (< 5 cps) or viscous ([Formula: see text]) consistency. After calculating a selection of generalized time, frequency, and time frequency features for each swallow, we compared our data against our findings in a previous experiment that investigated identical features for a different group of 56 healthy subjects.

RESULTS

We found that nearly all of our chosen features for both vibrations and sounds showed significant differences between the healthy and disordered swallows despite the absence of aspiration. We also found only negligible differences between dysphagia as a symptom of stroke and dysphagia as a symptom of another condition.

CONCLUSION

Non-aspirating swallows from healthy controls and patients with dysphagia have distinct feature patterns. These findings should greatly help the development of the cervical auscultation field and serve as a reference for future investigations into more specialized characterization methods.

Utility of Pulse Oximetry to Detect Aspiration: An Evidence-Based Systematic Review

Pulse oximetry is a commonly used means to measure peripheral capillary oxyhemoglobin saturation (SpO₂). Potential use of pulse oximetry to detect aspiration is attractive to clinicians, as it is readily available, quick, and noninvasive. However, research regarding validity has been mixed. This systematic review examining evidence on the use of pulse oximetry to detect a decrease in SpO₂ indicating aspiration during swallowing is undertaken to further inform clinical practice in dysphagia assessment. A multi-engine electronic search was conducted on 8/25/16 and updated on 4/8/17 in accordance with standards published by the Preferred Reporting for Items for Systematic Reviews and Meta-Analysis Protocols (PRISMA). Inclusion criteria included use of pulse oximetry to detect aspiration with simultaneous confirmation of aspiration via a gold standard instrumental study. Keywords included dysphagia or aspiration AND pulse oximetry. Articles meeting criteria were reviewed by two blinded co-investigators. The search yielded 294 articles, from which 19 were judged pertinent and reviewed in full. Ten met the inclusion criteria and all were rated at Level III-2 on the Australian Diagnostic Levels of Evidence. Study findings were mixed with sensitivity ranging from 10 to 87%. Potentially confounding variables were observed in all studies reviewed, and commonly involved defining "desaturation" within a standard measurement error range (~ 2%), mixed populations, mixed viscosities/textures observed during swallowing, and lack of comparison group. The majority of studies failed to demonstrate an association between observed aspiration and oxygen desaturation. Current evidence does not support the use of pulse oximetry to detect aspiration.

Measurement of Oxygen Desaturation Is Not Useful for the Detection of Aspiration in Dysphagic Stroke Patients

Background

Dysphagia is one of the most dangerous symptoms of acute stroke. Various screening tools have been suggested for the early detection of this condition. In spite of conflicting results, measurement of oxygen saturation (SpO₂) during clinical swallowing assessment is still recommended by different national guidelines as a screening tool with a decline in SpO₂ ≥2% usually being regarded as a marker of aspiration. This paper assesses the sensitivity of SpO₂ measurements for the evaluation of aspiration risk in acute stroke patients.

Methods

Fifty acute stroke patients with moderate to severe dysphagia were included in this study. In all patients, fiberoptic endoscopic evaluation of swallowing (FEES) was performed according to a standardised protocol. Blinded to the results of FEES, SpO₂ was monitored simultaneously. The degree of desaturation during/after swallows with aspiration was compared to the degree of desaturation during/after swallows without aspiration in a swallow-to-swallow analysis of each patient. To minimise potential confounders, every patient served as their control.

Results

In each subject, a swallow with and a swallow without aspiration were analysed. Overall, aspiration seen in FEES was related to a minor decline in SpO₂ (mean SpO₂ without aspiration 95.54 ± 2.7% vs. mean SpO₂ with aspiration 95.28 ± 2.7%). However, a significant desaturation ≥2% occurred only in 5 patients during/after aspiration. There was no correlation between aspiration/dysphagia severity or the amount of aspirated material and SpO₂ levels.

Conclusions

According to this study, measurement of oxygen desaturation is not a suitable screening tool for the detection of aspiration in stroke patients.

The effect of tongue strength on meal consumption in long term care

PURPOSE

As many as 74% of residents in long-term care (LTC) are anticipated to have swallowing difficulties (dysphagia). Low food intake is commonly reported in persons with swallowing problems, but food intake may also be affected by fatigue in the swallowing muscles. As fatigue sets in during mealtimes, the strength of the tongue may decline. Tongue strength is also known to decline with age but it is unclear how this functional change may influence food intake. In this pilot study, we explored the relationship between tongue strength and meal consumption in persons not previously diagnosed with dysphagia.

METHODS

The Iowa Oral Performance Instrument was used to collect maximum anterior isometric tongue-palate pressures from 12 LTC residents (5 male; mean age: 85, range 65-99). Residents were also screened for dysphagia with applesauce and a water swallow test. Each resident was observed at three different meals to record the length of time taken to eat the meal, amount of food consumed, and any indication of overt signs of swallowing difficulty (e.g. coughing).

RESULTS

Residents who displayed observable swallowing difficulties at mealtimes had significantly lower tongue strength than those without swallowing difficulties (p < 0.01). Those with lower tongue strength took significantly longer to complete meals (p < 0.05) and consumed less food. Tongue strength was not predictive of performance on the water screen and the water swallow test was not a good predictor of which participants were observed to display mealtime difficulties.

CONCLUSION

Among seniors in long term care, reduced tongue strength is associated with longer meal times, reduced food consumption, and the presence of observable signs of swallowing difficulty. Further exploration of these relationships is warranted.

Dysphagia Screening: Contributions of Cervical Auscultation Signals and Modern Signal-Processing Techniques

Cervical auscultation is the recording of sounds and vibrations caused by the human body from the throat during swallowing. While traditionally done by a trained clinician with a stethoscope, much work has been put towards developing more sensitive and clinically useful methods to characterize the data obtained with this technique. The eventual goal of the field is to improve the effectiveness of screening algorithms designed to predict the risk that swallowing disorders pose to individual patients' health and safety. This paper provides an overview of these signal processing techniques and summarizes recent advances made with digital transducers in hopes of organizing the highly varied research on cervical auscultation. It investigates where on the body these transducers are placed in order to record a signal as well as the collection of analog and digital filtering techniques used to further improve the signal quality. It also presents the wide array of methods and features used to characterize these signals, ranging from simply counting the number of swallows that occur over a period of time to calculating various descriptive features in the time, frequency, and phase space domains. Finally, this paper presents the algorithms that have been used to classify this data into 'normal' and 'abnormal' categories. Both linear as well as non-linear techniques are presented in this regard.

Swallowing accelerometry signal feature variations with sensor displacement

Dual-axis accelerometry has recently shown promise as a non-invasive method for detecting swallowing impairment using signal processing and pattern classification algorithms. However, it is unknown whether variations in sensor placement alter signal characteristics, threatening the accuracy of signal processing classifiers for aspiration detection. To address this question, water swallows were recorded in 14 healthy adults using a dual-axis accelerometer in 13 different positions (baseline, and 2, 4, 6 and 8 mm above, below and to the right of baseline). The baseline position was midline, immediately below the thyroid cartilage during quiet breathing. After segmentation and pre-processing, signal features were extracted in multiple domains (time, frequency, time-frequency). The effect of sensor position on signal feature distributions was examined with non-parametric statistical analysis. The analysis showed that the sensor could be displaced by as much as 4 mm inferior and lateral to the baseline position and by up to 6 mm above the baseline location without significantly altering time-frequency features. In other words, when considering the baseline position as the origin, the admissible region for sensor placement spans 10 mm in the superior-inferior axis and 8 mm in the medial-lateral direction. Results of this study suggest that time-frequency representations of accelerometry signals are most robust to sensor placement variations around the baseline position. The implication of this finding is that a swallowing accelerometry classifier based on time-frequency features can likely tolerate small variations in sensor location without degradation in classification performance.

Characteristics of Dry Chin-Tuck Swallowing Vibrations and Sounds

OBJECTIVE

The effects of the chin-tuck maneuver, a technique commonly employed to compensate for dysphagia, on cervical auscultation are not fully understood. Characterizing a technique that is known to affect swallowing function is an important step on the way to developing a new instrumentation-based swallowing screening tool.

METHODS

In this study, we recorded data from 55 adult participants who each completed five saliva swallows in a chin-tuck position. The resulting data were processed using previously designed filtering and segmentation algorithms. We then calculated nine time-, frequency-, and time-frequency-domain features for each independent signal.

RESULTS

We found that multiple frequency- and time-domain features varied significantly between male and female subjects as well as between swallowing sounds and vibrations. However, our analysis showed that participant age did not play a significant role on the values of the extracted features. Finally, we found that various frequency features corresponding to swallowing vibrations did demonstrate statistically significant variation between the neutral and chin-tuck positions but sounds showed no changes between these two positions.

CONCLUSION

The chin-tuck maneuver affects many facets of swallowing vibrations and sounds and its effects can be monitored via cervical auscultation.

SIGNIFICANCE

These results suggest that a subject's swallowing technique does need to be accounted for when monitoring their performance with cervical auscultation-based instrumentation.

A comparative analysis of swallowing accelerometry and sounds during saliva swallows

BACKGROUND

Accelerometry (the measurement of vibrations) and auscultation (the measurement of sounds) are both non-invasive techniques that have been explored for their potential to detect abnormalities in swallowing. The differences between these techniques and the information they capture about swallowing have not previously been explored in a direct comparison.

METHODS

In this study, we investigated the differences between dual-axis swallowing accelerometry and swallowing sounds by recording data from adult participants and calculating a number of time and frequency domain features. During the experiment, 55 participants (ages 18-65) were asked to complete five saliva swallows in a neutral head position. The resulting data was processed using previously designed techniques including wavelet denoising, spline filtering, and fuzzy means segmentation. The pre-processed signals were then used to calculate 9 time, frequency, and time-frequency domain features for each independent signal. Wilcoxon signed-rank and Wilcoxon rank-sum tests were utilized to compare feature values across transducers and patient demographics, respectively.

RESULTS

In addition to finding a number of features that varied between male and female participants, our statistical analysis determined that the majority of our chosen features were statistically significantly different across the two sensor methods and that the dependence on within-subject factors varied with the transducer type. However, a regression analysis showed that age accounted for an insignificant amount of variation in our signals.

CONCLUSIONS

We conclude that swallowing accelerometry and swallowing sounds provide different information about deglutition despite utilizing similar transduction methods. This contradicts past assumptions in the field and necessitates the development of separate analysis and processing techniques for swallowing sounds and vibrations.

Aging-related changes in swallowing, and in the coordination of swallowing and respiration determined by novel non-invasive measurement techniques

AIM

Previous studies have shown that the process of swallowing changes with aging, a phenomenon known as presbyphagia. These subtle and subclinical age-related changes make older adults more vulnerable to dysphagia during disease insults. However, there are limited studies of the swallowing process in older adults, because measurements are typically invasive or require exposure to X-rays. In the present study, we used integrated non-invasive measurements to determine aging-related changes of swallowing, and in the coordination of swallowing and respiration for a population of healthy participants.

METHODS

The non-invasive system provided measurements of larynx movement with piezoelectric sensors, submental muscle activity with surface electromyography and respiration-swallowing coordination by measurement of nasal airflow. We recruited 112 healthy participants from the community, 35 in a young-age group (age 20-30 years), 38 in a middle-age group (age 31-50 years) and 39 in an old-age group (age 51-70 years).

RESULTS

The oropharyngeal swallowing parameters of the old-age group had delayed onset latency and longer swallowing apnea duration relative to the other groups, and these differences were greater for larger boluses. The middle- and old-age groups had less expiratory-expiratory respiratory phase pattern than the young-age group. The probability of piecemeal deglutition was highest in the old-age group and lowest in the young-age group. These results show that the phases of oropharyngeal swallowing and the coordination of swallowing with respiration gradually change with aging.

CONCLUSIONS

We used integrated non-invasive measurements to document age-related changes in swallowing, and in the coordination of swallowing and respiration in healthy adults.

Swallowing disorders in tracheostomised patients: a multidisciplinary/multiprofessional approach in decannulation protocols

Safe removal of tracheal cannula is a major goal in the rehabilitation of tracheostomised patients to achieve progressive independence from mechanical support and reduce the risk of respiratory complications. A tracheal cannula may also cause significant discomfort to the patient, making verbal communication difficult. Particularly when cuffed, tracheal cannula reduces the normal movement of the larynx which can further compromise the basic swallowing defect. A close connection between respiratory, phonating, swallowing and feeding abilities to be recovered, implies a strict integration among different professionals of the rehabilitation team. An appropriate management of tracheostomy cannula is closely connected with assessment and treatment of swallowing disorders in order to limit the development of severe pulmonary and nutritional complications, but at present there are no uniform protocols in the scientific literature. Furthermore, several studies report as an essential criterion for decannulation the presence of good patient consciousness, which is often altered in patients with tracheostomy, but a general agreement is lacking.

Physiological factors related to aspiration risk: a systematic review

Penetration-aspiration is considered the most serious component of oropharyngeal dysphagia. Clinicians regularly evaluate the pathophysiology of swallowing and postulate reasons or mechanisms behind penetration-aspiration. In this article we share the results of a two-stage literature review designed to elucidate the association between abnormalities in physiological measures of swallowing function and the occurrence of penetration-aspiration. In the first stage, a broad scoping review was undertaken using search terms for nine different structures involved in oropharyngeal swallowing. In the second stage, based on the results of the initial search, a more focused systematic review was undertaken which explored the association between aspiration and abnormalities in respiratory, tongue, hyoid, and laryngeal function in swallowing. A total of 37 articles underwent detailed quality review and data extraction in the systematic review. The results support measurement of tongue strength, anatomically normalized measures of hyoid movement, bolus dwell time in the pharynx while the larynx remains open, respiratory rate, and respiratory swallow phasing as parameters relevant to aspiration risk.

Assessing swallowing disorders online: a pilot telerehabilitation study

OBJECTIVE

Dysphagia (a swallowing disorder) is known to occur in numerous clinical populations, but unfortunately because of issues accessing speech pathology services, not all patients are able to receive dysphagia intervention and rehabilitation services in a timely manner. Existing research supports the use of telehealth technology for providing various aspects of speech pathology service; however, to date there is limited evidence to support the utilization of telerehabilitation in the assessment and management of dysphagia. The aim of this research was to provide pilot information on the basic feasibility and validity of conducting dysphagia assessments via telerehabilitation.

MATERIALS AND METHODS

Ten simulated patients, actors portraying patients with a range of swallowing difficulties, were used rather than actual patients to minimize any potential patient risk from unidentified aspiration. Dysphagia was assessed simultaneously by a face-to-face (FTF) and telerehabilitation speech pathologist (T-SP). Each simulated patient was assessed using a Clinical Swallowing Examination (CSE) protocol that was modified to suit a telerehabilitation environment. The CSE was administered with the support of an assistant via an Internet-based videoconferencing telerehabilitation system using a bandwidth of 128 kilobits per second.

RESULTS

Results revealed high to excellent levels of agreement between the T-SP and the FTF-SP across all parameters of the CSE. Agreement for aspiration risk was excellent.

CONCLUSION

The pilot data indicate that the current model of administering a CSE via telerehabilitation has potential to be a feasible and valid method for the remote assessment of swallowing disorders.

Classification of healthy and abnormal swallows based on accelerometry and nasal airflow signals

BACKGROUND

Dysphagia assessment involves diagnosis of individual swallows in terms of the depth of airway invasion and degree of bolus clearance. The videofluoroscopic swallowing study is the current gold standard for dysphagia assessment but is time-consuming and costly. An ideal alternative would be an automated abnormal swallow detection methodology based on non-invasive signals.

OBJECTIVE

Building upon promising results from single-axis cervical accelerometry, the objective of this study was to investigate the combination of dual-axis accelerometry and nasal airflow for classification of healthy and abnormal swallows in a patient population with dysphagia.

METHODS

Signals were acquired from 24 adult patients with dysphagia (17.8±8.8 swallows per patient). The abnormality of each swallow was quantified using 4-point videofluoroscopic rating scales for its depth of airway invasion, bolus clearance from the valleculae, and bolus clearance from the pyriform sinuses. For each scale, we endeavored to automatically discriminate between the 2 extreme ratings, yielding 3 separate binary classification problems. Various time, frequency, and time-frequency domain features were extracted. A genetic algorithm was deployed for feature selection. Smoothed bootstrapping was utilized to balance the two classes and provide sufficient training data for a multidimensional feature space.

RESULTS

A Euclidean linear discriminant classifier resulted in a mean adjusted accuracy of 74.7% for the depth of airway invasion rating, whereas Mahalanobis linear discriminant classifiers yielded mean adjusted accuracies of 83.7% and 84.2% for bolus clearance from the valleculae and pyriform sinuses, respectively. The bolus clearance from the valleculae problem required the lowest feature space dimensionality. Wavelet features were found to be most discriminatory.

CONCLUSIONS

This exploratory study confirms that dual-axis accelerometry and nasal airflow signals can be used to discriminate healthy and abnormal swallows from patients with dysphagia. The fact that features from all signal channels contributed discriminatory information suggests that multi-sensor fusion is promising in abnormal swallow detection.

Effects of liquid stimuli on dual-axis swallowing accelerometry signals in a healthy population

Background

Dual-axis swallowing accelerometry has recently been proposed as a tool for non-invasive analysis of swallowing function. Although swallowing is known to be physiologically modifiable by the type of food or liquid (i.e., stimuli), the effects of stimuli on dual-axis accelerometry signals have never been thoroughly investigated. Thus, the objective of this study was to investigate stimulus effects on dual-axis accelerometry signal characteristics. Signals were acquired from 17 healthy participants while swallowing 4 different stimuli: water, nectar-thick and honey-thick apple juices, and a thin-liquid barium suspension. Two swallowing tasks were examined: discrete and sequential. A variety of features were extracted in the time and time-frequency domains after swallow segmentation and pre-processing. A separate Friedman test was conducted for each feature and for each swallowing task.

Results

Significant main stimulus effects were found on 6 out of 30 features for the discrete task and on 5 out of 30 features for the sequential task. Analysis of the features with significant stimulus effects suggested that the changes in the signals revealed slower and more pronounced swallowing patterns with increasing bolus viscosity.

Conclusions

We conclude that stimulus type does affect specific characteristics of dual-axis swallowing accelerometry signals, suggesting that associated clinical screening protocols may need to be stimulus specific.

Identification and nursing management of dysphagia in individuals with acute neurological impairment (update)

BACKGROUND

Dysphagia, or difficulty in swallowing, is a serious and life threatening medical condition that affects a significant number of individuals with neurological impairment. Nurses, who are available to patients 24 hours a day, are in the ideal position to identify individuals with swallowing difficulties and initiate interventions that may prevent further complications until a formal assessment can be undertaken. Appropriate assessment of swallowing function is essential to the accurate identification and diagnosis of deficits in swallowing and to the effective management of dysphagia.

OBJECTIVES

What is the nursing role in the recognition and management of dysphagia in adults with neurological impairment?Is there evidence on the effectiveness of nursing interventions in the recognition and management of dysphagia?

INCLUSION CRITERIA

Types of participants- Adult patients over the age of 18 years with neurogenic dysphagia secondary to acute neurological impairment were the chief population of interest; studies of nurses caring for these patients were also included.Types of interventions- This review included studies which used various interventions which focussed on the nursing role in recognition and nursing management of dysphagia; any formal observation of ability to swallow undertaken / documented by nurses; Clinical / Bedside Swallowing Assessment undertaken by nurses; and/or pulse oximetry monitoring.Types of outcomes- Early recognition by nurses of those with difficulty swallowingTypes of studies- Original quantitative research studies with a range of study designs such as randomised controlled trials, quasi-randomised trials, observational and descriptive studies.

EXCLUSION CRITERIA

Studies focussing solely on diagnostic procedures ordered or undertaken by either medical professionals or speech-language pathologist (such as videofluoroscopy/VFSS) were not of interest to this review.

SEARCH STRATEGY

A comprehensive search of a wide variety of published and unpublished sources was undertaken for the period between January 1998 and January 2008 using as main keywords: dysphagia (text word and MH) or gag reflex or swallow or "deglutition disorder" (text word and MH); problem or impair or difficult; neurological and impair or stroke or bedside swallowing assessment; MH "Brain Diseases+" or neurological and impair* or disorder* disease* or malfunction.

METHODOLOGICAL QUALITY

Quantitative papers selected for retrieval were assessed by two independent reviewers for methodological validity prior to inclusion in the review. Any disagreements that arose between the reviewers were resolved through discussion, or with a third reviewer.

DATA EXTRACTION

The data extracted included specific details about the interventions, populations, study methods and outcomes of significance to the review question and specific objectives.

DATA SYNTHESIS

Due to significant variability in study methodology, populations and interventions, no statistical meta-analysis was possible. Results are presented in narrative and tabular form instead.

RESULTS

Forty-two quantitative studies were retrieved and, of these, 17 met the inclusion and quality criteria, representing a wide range of quantitative research methodologies.

CONCLUSIONS

The evidence from this updated review indicates that nurses are well-placed to conduct dysphagia assessments and that there are several tools available that may be suitable for them to use. It is important that formal dysphagia screening protocols are in place and that nurses are trained to use them. If nurses screen patients with an acute neurological impairment within 24 hours of admission, it may reduce the time that patients spend without appropriate methods of nutrition and hydration and improve clinical outcomes. Dysphagia screening by nurses does not replace assessment by other health professionals; instead it enhances the provision of care to patients at risk allowing for early recognition and intervention to occur.

Swallow segmentation with artificial neural networks and multi-sensor fusion

Swallow segmentation is a critical precursory step to the analysis of swallowing signal characteristics. In an effort to automatically segment swallows, we investigated artificial neural networks (ANN) with information from cervical dual-axis accelerometry, submental MMG, and nasal airflow. Our objectives were (1) to investigate the relationship between segmentation performance and the number of signal sources and (2) to identify the signals or signal combinations most useful for swallow segmentation. Signals were acquired from 17 healthy adults in both discrete and continuous swallowing tasks using five stimuli. Training and test feature vectors were constructed with variances from single or multiple signals, estimated within 200 ms moving windows with 50% overlap. Corresponding binary target labels (swallow or non-swallow) were derived by manual segmentation. A separate 3-layer ANN was trained for each participant-signal combination, and all possible signal combinations were investigated. As more signal sources were included, segmentation performance improved in terms of sensitivity, specificity, accuracy, and adjusted accuracy. The combination of all four signal sources achieved the highest mean accuracy and adjusted accuracy of 88.5% and 89.6%, respectively. A-P accelerometry proved to be the most discriminatory source, while the inclusion of MMG or nasal airflow resulted in the least performance improvement. These findings suggest that an ANN, multi-sensor fusion approach to segmentation is worthy of further investigation in swallowing studies.

Bedside screening tests vs. videofluoroscopy or fibreoptic endoscopic evaluation of swallowing to detect dysphagia in patients with neurological disorders: systematic review

AIM

This paper is a report of a systematic review conducted to determine the effectiveness and feasibility of bedside screening methods for detecting dysphagia in patients with neurological disorders.

BACKGROUND

Dyspaghia affects 22-65% of patients with neurological conditions. Although there is a large variety of bedside tests to detect dysphagia, it is unknown which have the best psychometric properties and are feasible for nurses to use.

DATA SOURCES AND REVIEW METHODS

An electronic database search was carried out using Medline (PubMed), Embase, CINAHL, and PsychLit, including all hits up to July 2008. The search terms were dysphagia, sensitivity, specificity, diagnosis, and screening. The methodological quality of included studies was assessed.

RESULTS

Thirty-five out of 407 studies were included in the review. Eleven studies with sufficient methodological quality revealed that trial swallow tests using water had sensitivities between 27% and 85% and specificities between 63% and 88%. Trial swallow tests with different viscosities led to sensitivities ranging from 41% to 100% and specificities of 57% to 82%. Combining water tests with oxygen desaturation led to sensitivities between 73% and 98% and specificities between 63% and 76%. Single clinical features, such as abnormal gag, generally had low sensitivity and specificity.

CONCLUSION

A water test combined with pulse oximetry using coughing, choking and voice alteration as endpoints is currently the best method to screen patients with neurological disorders for dysphagia. Further research is needed to establish the most effective standardized administration procedure for such a water test, and to assess the value of pulse oximetry, in addition to a trial swallow to detect silent aspiration.

The use of pulse oximetry as a screening assessment for paediatric neurogenic dysphagia

PURPOSE

Early screening and intervention for dysphagia is crucial to offset potential outcomes such as compromised nutrition or reduced respiratory function. Current paediatric dysphagia screening tests are subjective with poor sensitivity and specificity. The present study examined whether an objective method, pulse oximetry (measuring oxygen saturation (SpO2) levels), could differentiate between children with and without dysphagia, in relation to (1) Average pre-feeding baseline SpO2 levels; (2) Average feeding SpO2 levels; (3) Average post-feeding SpO2 levels; and (4) The number of events of oxygen desaturation pre-, during and after feeding.

METHODS

Nine participants with chronic neurological disability (CND) (7 F, 2 M) (9; 7-15; 11 years) and nine control participants matched for age (9; 5-16; 0 years) and sex were assessed using a clinical bedside evaluation (CBE) and pulse oximetry.

RESULTS

A statistically significant difference was found in SpO2 levels between the two groups (p < 0.001) during oral feeding only (sensitivity, 88.9%; specificity, 88.9%). Only three children with dysphagia experienced 'events' of SpO2 desaturation during feeding.

CONCLUSION

Pulse oximetry may provide a useful adjunct to the CBE for dysphagia screening, with average SpO2 levels during feeding predicting those with and without dysphagia with moderate levels of sensitivity and specificity. The finding of individual variation in desaturation 'events', however, warrants the provision of further data on large homogenous populations to provide definitive criterion for pathological SpO2 levels associated with dysphagia during oral feeding.

Can pulse oximetry or a bedside swallowing assessment be used to detect aspiration after stroke?

BACKGROUND AND PURPOSE

Desaturation during swallowing may help to identify aspiration in stroke patients. This study investigated pulse oximetry, bedside swallowing assessment (BSA), and videofluoroscopy as tests for detecting aspiration after stroke.

METHODS

Swallowing was assessed in 189 stroke patients (mean+/-SD age, 70.9+/-12.3 years) within 5 days of symptom onset with a modified BSA (water replaced by radio-opaque contrast agent, followed by chest radiography to detect aspiration). Simultaneous pulse oximetry recorded the greatest desaturation from baseline for 10 minutes from modified BSA onset. Videofluoroscopy was undertaken in 54 (28%) patients.

RESULTS

Modified BSA showed a safe swallow in 98 (51.9%), unsafe swallow in 85 (45.0%), and silent aspiration in 6 (3.2%) patients. During swallowing, desaturation by >2% occurred in 27 (27.6%) and by >5% in 3 (3.1%) of the 98 safe-swallow patients on modified BSA. Of the 85 unsafe-swallow patients, only 28 (32.9%) desaturated by >2% and 6 (7.1%) by >5%. Desaturation did not occur in any of the 6 silent aspirators. With the modified BSA to detect aspiration, sensitivity and specificity, respectively, were 0.31 and 0.72 for desaturation >2% and 0.07 and 0.97 for desaturation >5%. By videofluoroscopy, sensitivity and specificity for detecting aspiration were 0.47 and 0.72 for modified BSA, 0.33 and 0.62 for desaturation >2%, and 0.13 and 0.95 for desaturation >5%. Combining a failed modified BSA with desaturation >2% or >5% did not significantly improve predictive values.

CONCLUSIONS

Modified BSA and pulse oximetry during swallowing, whether alone or in combination, showed inadequate sensitivity, specificity, and predictive values for detection of aspiration compared with videofluoroscopy in stroke patients.

A radial basis classifier for the automatic detection of aspiration in children with dysphagia

Background

Silent aspiration or the inhalation of foodstuffs without overt physiological signs presents a serious health issue for children with dysphagia. To date, there are no reliable means of detecting aspiration in the home or community. An assistive technology that performs in these environments could inform caregivers of adverse events and potentially reduce the morbidity and anxiety of the feeding experience for the child and caregiver, respectively. This paper proposes a classifier for automatic classification of aspiration and swallow vibration signals non-invasively recorded on the neck of children with dysphagia.

Methods

Vibration signals associated with safe swallows and aspirations, both identified via videofluoroscopy, were collected from over 100 children with neurologically-based dysphagia using a single-axis accelerometer. Five potentially discriminatory mathematical features were extracted from the accelerometry signals. All possible combinations of the five features were investigated in the design of radial basis function classifiers. Performance of different classifiers was compared and the best feature sets were identified.

Results

Optimal feature combinations for two, three and four features resulted in statistically comparable adjusted accuracies with a radial basis classifier. In particular, the feature pairing of dispersion ratio and normality achieved an adjusted accuracy of 79.8 ± 7.3%, a sensitivity of 79.4 ± 11.7% and specificity of 80.3 ± 12.8% for aspiration detection. Addition of a third feature, namely energy, increased adjusted accuracy to 81.3 ± 8.5% but the change was not statistically significant. A closer look at normality and dispersion ratio features suggest leptokurticity and the frequency and magnitude of atypical values as distinguishing characteristics between swallows and aspirations. The achieved accuracies are 30% higher than those reported for bedside cervical auscultation.

Conclusion

The proposed aspiration classification algorithm provides promising accuracy for aspiration detection in children. The classifier is conducive to hardware implementation as a non-invasive, portable "aspirometer". Future research should focus on further enhancement of accuracy rates by considering other signal features, classifier methods, or an augmented variety of training samples. The present study is an important first step towards the eventual development of wearable intelligent intervention systems for the diagnosis and management of aspiration.

Using a monitored test to assess risk of aspiration in postoperative patients

Pulmonary aspiration is associated with high morbidity and mortality rates. Older adult patients have been shown to be particularly at risk for aspiration. A randomized controlled trial was conducted to investigate the efficacy of a simple, noninvasive screening test-the monitored sip test-in identifying patients at risk for aspiration, including "silent aspirators." Based on clinical judgment using the study's outcome measures, incidence of aspiration-related lung injury was high (ie, 37.5%); however, no identification of patients at risk for aspiration occurred after either the use of the monitored sip test or routine cautious introduction of fluids during the data collection phase of the study.

Effect of Tactile Stimulation on Lingual Motor Function in Pediatric Lingual Dysphagia

There is a scarcity of empirical evidence on effective treatments of swallowing dysfunction in young children who do not suck or swallow. There is no literature testing the effects of shaping a reflex or specifically shaping a swallow reflex. The purpose of this retrospective study was to investigate and isolate the specific regional mechanical functions of the tongue during swallowing. This study included 45 patients who did not swallow because of multiple congenital anomalies and gastroenterologic dysfunctions before and after corrective surgery and had histories of unsuccessful traditional feeding therapies. Evaluation included clinical gastroenterologic, nutritional, and neurologic examination, routine laboratory tests, and radiologic swallowing studies. A ten-year study analyzed the behavioral science procedures shaping both a swallow reflex and lingual surface geometry. Treatment variables were (1) a tactile stimulus to the posterior tongue and (2) sequential tactile stimuli to varied locations on the lingual surface. There were significant differences in lingual responses for all patients who were transferred from artificial feedings to independent prototypical swallowing capability and acquired oral consumption of recommended daily hydration and nutrition in 5-7 days of treatment. The initial tactile stimulus and six-level sequential stimuli resulted in six sequential lingual responses within each wavelike swallow reflex. Results of stimuli shaping varied lingual responses across 45 patients with severe multiple medical and anatomical deficits in swallowing, suggest that the etiology was not relevant in this population. These behavioral science approaches are novel treatment for pediatric lingual dysphagia.

Pulse oximetry does not reliably detect aspiration on videofluoroscopic swallowing study

OBJECTIVE

To examine the reliability of pulse oximetry for identifying aspiration by comparing it with the videofluoroscopic swallowing study (VFSS).

DESIGN

Nonrandomized, prospective, double-blind study.

SETTING

VFSS laboratory in a teaching hospital.

PARTICIPANTS

Sixty patients from among 130 patients with clinically diagnosed dysphagia between September and December 2002.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Simultaneously monitoring the arterial oxygen saturation (Sp o 2 ) by pulse oximetry while patients were performing VFSS. A decrease in Sp o 2 exceeding 3% was considered as significant desaturation. Bolus or portion of bolus passing through the vocal cords and entering the subglottic space was defined as aspiration on VFSS. The results of pulse oximetry and VFSS were compared.

RESULTS

No significant correlation existed between desaturation measured by pulse oximetry and aspiration on VFSS (chi 2 test, P =.87). The positive predictive rate of pulse oximetry in detecting aspiration on VFSS was 39.1%, and the negative predictive rate was 59.4%.

CONCLUSIONS

Aspiration occurring on VFSS cannot be predicted based on decrease in Sp o 2 in pulse oximetry. The application of pulse oximetry to detect aspiration during regular meals requires further investigation.

Pulse oximetry in supportive and palliative care

Pulse oximetry is a valuable, non-invasive method used for estimating oxyhaemoglobin saturation. It can give a bedside indication of the oxygenation and thus provide a valuable insight into the cause of breathlessness. Its use can help palliative care teams to determine the need to prescribe or to withhold oxygen therapy. The technology is well established and relatively inexpensive. Factors that influence readings include low perfusion states at the end of life. With a thorough understanding of its uses and limitations, pulse oximetry can assist multidisciplinary teams in providing better care to ill patients in the palliative care setting.

Early assessments of dysphagia and aspiration risk in acute stroke patients

BACKGROUND AND PURPOSE

Dysphagia is common after stroke and is a marker of poor prognosis. Early identification is important. This article reviews the merits and limitations of various assessment methods available to clinicians.

METHODS

An electronic database search was performed of MEDLINE, EMBASE, and the Cochrane database using such terms as stroke, aspiration, dysphagia, and assessment; extensive manual searching of articles was also conducted.

RESULTS

Bedside tests are safe, relatively straightforward, and easily repeated but have variable sensitivity (42% to 92%), specificity (59% to 91%), and interrater reliability (kappa=0 to 1.0). They are also poor at detecting silent aspiration. Videofluoroscopy gives anatomic and functional information and allows testing of therapeutic techniques. However, swallowing is assessed under ideal conditions that are different from clinical settings, and reliability is often poor (kappa=0 to 0.75) in the absence of assessor training. Fiberoptic endoscopy allows swallow assessment and sensory testing but requires specialized staff and equipment. Oxygen desaturation during swallowing may be predictive of aspiration (sensitivity, 73% to 87%; specificity, 39% to 87%) but is more useful in combination with bedside testing than in isolation. Other methods of swallow testing are invasive and require specialized staff and equipment.

CONCLUSIONS

Although bedside tests remain an important early screening tool for dysphagia and aspiration risk, further refinements are needed to improve their accuracy.

Treatment of lipid disorders after stroke

The efficacy of lipid disorder therapy for the primary and secondary prevention of coronary heart disease is established. There are, however, no completed studies specifically directed at reducing the risk of stroke with lipid therapy. Although observational cohort studies have failed to demonstrate an association between lipid disorders and stroke incidence, recently completed trials of subjects at risk for coronary heart disease have shown that statins and fibric acid derivatives reduce not only the risk of myocardial infarction and death, but also that of brain infarction and transient ischemic attacks. Lipid drugs are well tolerated and treatment complications are relatively low. It seems prudent to conclude that the stroke patient with an undesirable lipid profile who has a history of coronary heart disease should receive specific treatment for the lipid disorder. Recommendations are more problematic for stroke patients with lipid disorders but no history of coronary heart disease; most should receive therapy for primary prevention of heart disease. Lipid treatment trials focused on stroke risk reduction are urgently needed.

Recent developments in diagnosis and intervention for aspiration and dysphagia in stroke and other neuromuscular disorders

This review discusses the impact of the evidence-based report on dysphagia diagnosis and treatment in stroke patients prepared in 1999 by ECRI under contract with the Agency for Healthcare Research and Quality (AHRQ). Subsequent research findings are highlighted and research design and reporting problems in the field are discussed. Progress has been made toward standardizing training and rating of videofluoroscopic studies of swallowing (VFSS); however, a consensus does not yet exist. A randomized, controlled trial demonstrated that treatment directed by fiber-optic endoscopic evaluation of swallowing with sensory testing (FEESST) or VFSS resulted in approximately equivalent pneumonia rates. These two different methods provide both overlapping and complementary information. There is discussion of the research design problems of mixed patients versus homogeneous populations, case-control diagnostic studies, inappropriate calculations of diagnostic sensitivity/specificity using imperfect "gold standards," the lack of concurrent control groups in treatment studies, and the misuse of statistical significance tests and P values in examining matching of patient characteristics in comparative studies and in identifying important variables in regression analysis.

Diagnosis and management of cricopharyngeal achalasia and other upper esophageal sphincter opening disorders

Recent literature on disorders of the upper esophageal sphincter is reviewed, including discussion of advances in measurement, diagnosis, treatment, and management. The etiology of upper esophageal sphincter disorders is summarized, along with its pathophysiology, with reference to gastroesophageal reflux disease. Medical and surgical options for improving pharyngeal clearance and minimizing aspiration are also discussed, as is the use of percutaneous esophageal gastrostomy feeding tubes.