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

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.

Predictors of dysphagia screening and pneumonia among patients with intracerebral haemorrhage in China: a cross-sectional hospital-based retrospective study

OBJECTIVES

This study aimed to investigate factors associated with undergoing dysphagia screening (DS) and developing pneumonia, as well as the relationship between DS and pneumonia in patients with intracerebral haemorrhage (ICH).

DESIGN

Our study was a cross-sectional hospital-based retrospective study.

STUDY DESIGN AND SETTINGS

We derived data from the China Stroke Centre Alliance, a nationwide clinical registry of ICH from 1476 participating hospitals in mainland China. To identify predictors for pneumonia, multivariable logistic regression models were used to identify patient characteristics that were independently associated with DS and pneumonia.

PARTICIPANTS

We included 31 546 patients in this study with patient characteristics, admission location, medical history, hospital characteristics and hospital grade from August 2015 to July 2019.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcomes were DS and pneumonia during acute hospitalisation.

RESULTS

In total, 25 749 (81.6%) and 7257 (23.0%) patients with ICH underwent DS and developed pneumonia. Compared with patients without pneumonia, those who developed pneumonia were older and had severe strokes (Glasgow Coma Scale 9-13: 52.7% vs 26.9%). Multivariable analyses revealed that a higher pneumonia risk was associated with dysphagia (OR, 4.34; 95% CI, 4.02 to 4.68), heart failure (OR, 1.85; 95% CI, 1.24 to 2.77) and smoking (OR, 1.12; 95% CI, 1.12 to 0.20). DS was associated with lower odds of pneumonia (OR, 0.65; 95% CI, 0.44 to 0.95).

CONCLUSION

Our findings further confirm that dysphagia is an independent risk factor for pneumonia; one-fifth of patients with ICH did not undergo DS. However, comprehensive dysphagia evaluation and effective management are crucial. Nursing processes ensure the collection of complete and accurate information during evaluation of patients. There is a need to increase the rate of DS in patients with ICH, especially those with severe stroke or older. Further, randomised controlled trials are warranted to determine the effectiveness of DS on clinical outcomes.

Food-Grade Activated Charcoal for Contrast-Enhanced Photoacoustic Imaging of Aspiration: A Phantom Study

Aspiration pneumonia has the highest attributable mortality of all medical complications post-stroke, or in individuals with progressive neurological diseases. For optimum health outcomes for individuals with dysphagia, a non-invasive and convenient method for objectively detecting aspiration is needed. This study introduces a potential new aspiration screening method based on photoacoustic imaging (PAI), a medical imaging technology that measures the optical contrast of tissue rather than mechanical or elastic properties. In this preliminary study, a tissue-mimicking neck phantom was designed to test the performance of PAI for aspiration screening with a charcoal solution as a contrast agent. A 1064 nm wavelength light source was illuminated on the anterior of the neck phantom to induce the photoacoustic effect. The resulting photoacoustic signal of the charcoal contrast in the mock trachea was detected by a linear transducer array with a 2.25 MHz central ultrasound frequency. The phantom results showed that charcoal solution at 10 mg/ml exhibited strong photoacoustic signals when flowing into the phantom trachea. By overlaying the photoacoustic signals of the charcoal contrast on top of the ultrasound image, we were able to simultaneously visualize the movement of food contrast and a cross-section of tissue structures during mock swallowing. Moreover, we confirmed the ability to detect the flow of charcoal contrast at a small bolus volume of ~ 7 μl through the phantom, suggesting high sensitivity to detect small aspiration events. The study suggests that PAI holds promise to be developed as an aspiration detection tool with charcoal powder as a contrast agent.

Peripheral Organ Injury After Stroke

Stroke is a disease with high incidence, mortality and disability rates. It is also the main cause of adult disability in developed countries. Stroke is often caused by small emboli on the inner wall of the blood vessels supplying the brain, which can lead to arterial embolism, and can also be caused by cerebrovascular or thrombotic bleeding. With the exception of recombinant tissue plasminogen activator (rt-PA), which is a thrombolytic drug used to recanalize the occluded artery, most treatments have been demonstrated to be ineffective. Stroke can also induce peripheral organ damage. Most stroke patients have different degrees of injury to one or more organs, including the lung, heart, kidney, spleen, gastrointestinal tract and so on. In the acute phase of stroke, severe inflammation occurs in the brain, but there is strong immunosuppression in the peripheral organs, which greatly increases the risk of peripheral organ infection and aggravates organ damage. Nonneurological complications of stroke can affect treatment and prognosis, may cause serious short-term and long-term consequences and are associated with prolonged hospitalization and increased mortality. Many of these complications are preventable, and their adverse effects can be effectively mitigated by early detection and appropriate treatment with various medical measures. This article reviews the pathophysiological mechanism, clinical manifestations and treatment of peripheral organ injury after stroke.

Japanese clinical practice guidelines for aspiration and pharyngeal residual assessment during eating and swallowing for nursing care

AIM

This clinical practice guideline aims to provide and recommend methods of assessing aspiration and pharyngeal residue during eating and swallowing and methods of selecting and implementing nursing care for adults to prevent the development of aspiration pneumonia through early and appropriate management of oropharyngeal dysphagia.

METHODS

In April 2018, the Japan Academy of Nursing Science established the Supervisory Committee in Nursing Care Development/Standardization Committee to develop clinical practice guidelines for aspiration and pharyngeal residual assessment during eating and swallowing for nursing care. This clinical practice guideline was developed according to the Minds Manual for Guideline Development 2017, with the aim of providing a specific pathway for nurses to determine the policy for selecting management for oropharyngeal dysphagia based on research evidence and multifaceted factors including the balance of benefits and harms and patients' values.

RESULTS

Based on the 10 clinical questions related to assessment by physical assessment, the Repetitive Saliva Swallowing Test, Modified Water Swallowing Test, Food Test, cervical auscultation, observation using an ultrasound diagnostic device, and an endoscope, 10 recommendations have been developed. Eight recommendations have been evaluated as the Grading of Recommendations Assessment, Development and Evaluation (GRADE) 2C, and the other two have been evaluated as no GRADE.

CONCLUSION

The first reliable clinical practice guideline has been produced from an academic nursing organization that focuses on assessment for nursing care and incorporates the latest 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.

Development of a Non-invasive Device for Swallow Screening in Patients at Risk of Oropharyngeal Dysphagia: Results from a Prospective Exploratory Study

Oropharyngeal dysphagia is prevalent in several at-risk populations, including post-stroke patients, patients in intensive care and the elderly. Dysphagia contributes to longer hospital stays and poor outcomes, including pneumonia. Early identification of dysphagia is recommended as part of the evaluation of at-risk patients, but available bedside screening tools perform inconsistently. In this study, we developed algorithms to detect swallowing impairment using a novel accelerometer-based dysphagia detection system (DDS). A sample of 344 individuals was enrolled across seven sites in the United States. Dual-axis accelerometry signals were collected prospectively with simultaneous videofluoroscopy (VFSS) during swallows of liquid barium stimuli in thin, mildly, moderately and extremely thick consistencies. Signal processing classifiers were trained using linear discriminant analysis and 10,000 random training-test data splits. The primary objective was to develop an algorithm to detect impaired swallowing safety with thin liquids with an area under receiver operating characteristic curve (AUC) > 80% compared to the VFSS reference standard. Impaired swallowing safety was identified in 7.2% of the thin liquid boluses collected. At least one unsafe thin liquid bolus was found in 19.7% of participants, but participants did not exhibit impaired safety consistently. The DDS classifier algorithms identified participants with impaired thin liquid swallowing safety with a mean AUC of 81.5%, (sensitivity 90.4%, specificity 60.0%). Thicker consistencies were effective for reducing the frequency of penetration-aspiration. This DDS reached targeted performance goals in detecting impaired swallowing safety with thin liquids. Simultaneous measures by DDS and VFSS, as performed here, will be used for future validation studies.

Swallowing and Aspiration Risk: A Critical Review of Non Instrumental Bedside Screening Tests

BACKGROUND AND PURPOSE

The presence of dysphagia and aspiration in stroke patients is associated with increased mortality and morbidity. Early recognition and management of these two conditions via reliable, minimally invasive bedside procedures before complications arise remains challenging in everyday clinical practice. This study reviews the available bedside screening tools for detecting swallowing status and aspiration risk in acute stroke by qualitatively observing reference population study design, clinical flexibility, reliability and applicability to acute-care settings.

METHODS

The primary search was conducted using the PubMed, Embase, and Cochrane Library databases. The search was limited to papers on humans written in English and published from 1991 to 2016. Eligibility criteria included the consecutive enrollment of acute-stroke inpatients and the development of a protocol for screening aspiration risk during oral feeding in this population.

RESULTS

Of the 652 sources identified, 75 articles were reviewed in full however, only 12 fulfilled the selection criteria. Notable deficiencies in most of the bedside screening protocols included poor methodological designs and inadequate predictive values for aspiration risk which render clinicians to be more conservative in making dietary recommendations.

CONCLUSIONS

The literature is dense with screening methods for assessing the presence of dysphagia but with low predictive value for aspiration risk after acute stroke. A standard, practical, and cost-effective screening tool that can be applied at the bedside and interpreted by a wide range of hospital personnel remains to be developed. This need is highlighted in settings where neither trained personnel in evaluating dysphagia nor clinical instrumentation procedures are available.

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.

[How reliable are non-instrumental assessment tools for dysphagia?]

BACKGROUND

The requirement for otorhinolaryngologists and phoniatricians to diagnose dysphagia and evaluate its extent is on the rise, particularly in light of demographic changes. The gold standards in confirmatory diagnostics are fiberoptic endoscopic evaluation of swallowing (FEES) and the videofluoroscopic swallowing examination (VFS). Standardized assessments, such as questionnaires or assessments involving probatory swallows are often applied as screening or supportive measures. This article aims to give a critical overview of the assessment tools frequently used in clinical routine. Test quality is assessed, particularly compared to FEES and VFS.

METHODS

A selective literature search using PubMed has been conducted.

RESULTS

On the basis of this lierature search, 48 assessment tools were identified. These can be classified into screening tools, instrument-based tools (implementation standards and evaluation protocols) and questionnaire-based assessment inventories.

DISCUSSION

In order to diagnose and evaluate dysphagia on the basis of assessment critieria, clinicians should be aware of indications for, as well as the advantages, disadvantages and test quality of the assessment tools. Considering the different assessment tools for anamnesis and probatory swallowing, rather low sensitivities and specificities for possible penetration and aspiration are evident. In cases where these symptoms of dysphagia are not evident and reliably assessable, confirmatory assessment via FEES or VFS is essential.

Bedside diagnosis of dysphagia: a systematic review

Dysphagia is associated with aspiration, pneumonia, and malnutrition, but remains challenging to identify at the bedside. A variety of exam protocols and maneuvers are commonly used, but the efficacy of these maneuvers is highly variable. We conducted a comprehensive search of 7 databases, including MEDLINE, Embase, and Scopus, from each database's earliest inception through June 9, 2014. Studies reporting diagnostic performance of a bedside examination maneuver compared to a reference gold standard (videofluoroscopic swallow study or flexible endoscopic evaluation of swallowing with sensory testing) were included for analysis. From each study, data were abstracted based on the type of diagnostic method and reference standard study population and inclusion/exclusion characteristics, design, and prediction of aspiration. The search strategy identified 38 articles meeting inclusion criteria. Overall, most bedside examinations lacked sufficient sensitivity to be used for screening purposes across all patient populations examined. Individual studies found dysphonia assessments, abnormal pharyngeal sensation assessments, dual axis accelerometry, and 1 description of water swallow testing to be sensitive tools, but none were reported as consistently sensitive. A preponderance of identified studies was in poststroke adults, limiting the generalizability of results. No bedside screening protocol has been shown to provide adequate predictive value for presence of aspiration. Several individual exam maneuvers demonstrated reasonable sensitivity, but reproducibility and consistency of these protocols was not established. More research is needed to design an optimal protocol for dysphagia detection.

Dysphagia associated with cervical spine and postural disorders

Difficulties with swallowing may be both persistent and life threatening for the majority of those who experience it irrespective of age, gender, and race. The purpose of this review is to define oropharyngeal dysphagia and describe its relationship to cervical spine disorders and postural disturbances due to either congenital or acquired disorders. The etiology and diagnosis of dysphagia are analyzed, focusing on cervical spine pathology associated with dysphagia as severe cervical spine disorders and postural disturbances largely have been held accountable for deglutition disorders. Scoliosis, kyphosis–lordosis, and osteophytes are the primary focus of this review in an attempt to elucidate the link between cervical spine disorders and dysphagia. It is important for physicians to be knowledgeable about what triggers oropharyngeal dysphagia in cases of cervical spine and postural disorders. Moreover, the optimum treatment for dysphagia, including the use of therapeutic maneuvers during deglutition, neck exercises, and surgical treatment, is discussed.

Guideline clinical nutrition in patients with stroke

Stroke is regularly accompanied by dysphagia and other factors associated with decreased nutritional intake. Dysphagia with aspiration pneumonia and insufficient nutritional intake lead to worse outcome after stroke.

This guideline is the first chapter of the guideline “Clinical Nutrition in Neurology” of the German Society for Clinical Nutrition (DGEM) which itself is one part of a comprehensive guideline about all areas of Clinical Nutrition. The thirty-one recommendations of the guideline are based on a systematic literature search and review, last updated December 31, 2011. All recommendations were discussed and consented at several consensus conferences with the entire DGEM guideline group. The recommendations underline the importance of an early screening and assessment of dysphagia and give advice for an evidence based and comprehensive nutritional management to avoid aspiration, malnutrition and dehydration.

Evaluation of dysphagia in early stroke patients by bedside, endoscopic, and electrophysiological methods

We aimed in this study to evaluate dysphagia in early stroke patients using a bedside screening test and flexible fiberoptic endoscopic evaluation of swallowing (FFEES) and electrophysiological evaluation (EE) methods and to compare the effectiveness of these methods. Twenty-four patients who were hospitalized in our clinic within the first 3 months after stroke were included in this study. Patients were evaluated using a bedside screening test [including bedside dysphagia score (BDS), neurological examination dysphagia score (NEDS), and total dysphagia score (TDS)] and FFEES and EE methods. Patients were divided into normal-swallowing and dysphagia groups according to the results of the evaluation methods. Patients with dysphagia as determined by any of these methods were compared to the patients with normal swallowing based on the results of the other two methods. Based on the results of our study, a high BDS was positively correlated with dysphagia identified by FFEES and EE methods. Moreover, the FFEES and EE methods were positively correlated. There was no significant correlation between NEDS and TDS levels and either EE or FFEES method. Bedside screening tests should be used mainly as an initial screening test; then FFEES and EE methods should be combined in patients who show risks. This diagnostic algorithm may provide a practical and fast solution for selected stroke patients.

Classification of penetration--aspiration versus healthy swallows using dual-axis swallowing accelerometry signals in dysphagic subjects

Swallowing accelerometry is a promising noninvasive approach for the detection of swallowing difficulties. In this paper, we propose an approach for classification of swallowing accelerometry recordings containing either healthy swallows or penetration-aspiration (entry of material into the airway) in dysphagic patients. The proposed algorithm is based on the wavelet packet decomposition of swallowing accelerometry signals in combination with linear discriminant analysis as a feature reduction method and Bayes classification. The proposed algorithm was tested using swallowing accelerometry signals collected from 40 patients during the regularly scheduled videoflouroscopy exam. The participants were instructed to swallow several 5-mL sips of thin liquid barium in a head neutral position. The results of our numerical analysis showed that the proposed algorithm can differentiate healthy swallows from aspiration swallows with an accuracy greater than 90%. These results position swallowing accelerometry as a valid approach for the detection of swallowing difficulties, particularly penetration-aspiration in patients suspected of dysphagia.

A method for removal of low frequency components associated with head movements from dual-axis swallowing accelerometry signals

Head movements can greatly affect swallowing accelerometry signals. In this paper, we implement a spline-based approach to remove low frequency components associated with these motions. Our approach was tested using both synthetic and real data. Synthetic signals were used to perform a comparative analysis of the spline-based approach with other similar techniques. Real data, obtained data from 408 healthy participants during various swallowing tasks, was used to analyze the processing accuracy with and without the spline-based head motions removal scheme. Specifically, we analyzed the segmentation accuracy and the effects of the scheme on statistical properties of these signals, as measured by the scaling analysis. The results of the numerical analysis showed that the spline-based technique achieves a superior performance in comparison to other existing techniques. Additionally, when applied to real data, we improved the accuracy of the segmentation process by achieving a 27% drop in the number of false negatives and a 30% drop in the number of false positives. Furthermore, the anthropometric trends in the statistical properties of these signals remained unaltered as shown by the scaling analysis, but the strength of statistical persistence was significantly reduced. These results clearly indicate that any future medical devices based on swallowing accelerometry signals should remove head motions from these signals in order to increase segmentation accuracy.

Scaling analysis of baseline dual-axis cervical accelerometry signals

Dual-axis cervical accelerometry is an emerging approach for the assessment of swallowing difficulties. However, the baseline signals, i.e., vibration signals with only quiet breathing or apnea but without swallowing, are not well understood. In particular, to comprehend the contaminant effects of head motion on cervical accelerometry, we need to study the scaling behavior of these baseline signals. Dual-axis accelerometry data were collected from 50 healthy adult participants under conditions of quiet breathing, apnea and selected head motions, all in the absence of swallowing. The denoised cervical vibrations were subjected to detrended fluctuation analysis with empirically determined first-order detrending. Strong persistence was identified in cervical vibration signals in both anterior-posterior (A-P) and superior-inferior (S-I) directions, under all the above experimental conditions. Vibrations in the A-P axes exhibited stronger correlations than those in the S-I axes, possibly as a result of axis-specific effects of vasomotion. In both axes, stronger correlations were found in the presence of head motion than without, suggesting that head movement significantly impacts baseline cervical accelerometry. No gender or age effects were found on statistical persistence of either vibration axes. Future developments of cervical accelerometry-based medical devices should actively mitigate the effects of head movement.

The effects of head movement on dual-axis cervical accelerometry signals

Background

Head motions can severely affect dual-axis cervical acceloremetry signals. A complete understanding of the effects of head motion is required before a robust accelerometry-based medical device can be developed. In this paper, we examine the spectral characteristics of dual-axis cervical accelerometry signals in the absence of swallowing but in the presence of head motions.

Findings

Data from 50 healthy adults were collected while participants performed five different head motions. Three different spectral features were extracted from each recording: peak frequency, spectral centroid and bandwidth. Statistical analyses showed that peak frequencies are independent of the type of head motion, participant gender and age. However, spectral centroids are statistically different between the anterior-posterior (A-P) and superior-inferior (S-I) directions and between different motion. Additionally, statistically different bandwidths are observed for head tilts down and back between the A-P and the S-I directions.

Conclusions

These differences indicate that head motions induce additional non-dominant spectral components in dual-axis cervical recordings. The results presented here suggest that head motion ought to be considered in the development of medical devices based on dual-axis cervical accelerometery signals.

Novel preventive and therapuetic strategy for post-stroke pneumonia

Pneumonia is a significant complication of ischemic stroke that increases mortality. Post-stroke pneumonia is defined as newly developed pneumonia following stroke onset. Clinically and chronologically, post-stroke pneumonia is divided into two types of aspiration pneumonia. First, acute-onset post-stroke pneumonia occurs within 1 month after stroke. Second, insidious or chronic-onset post-stroke pneumonia occurs 1 month after the stroke. The mechanisms of pneumonia are apparent aspiration and dysphagia-associated microaspiration. Stroke and the post-stroke state are the most significant risk factors for aspiration pneumonia. The preventive and therapeutic strategies have been developed thoroughly and appropriate antibiotic use, and both pharmacological and nonpharmacological approaches for the treatment of post-stroke pneumonia have been studied rigorously. Increases in substance P levels, oral care, and swallowing rehabilitation are necessary to improve swallowing function in post-stroke patients, resulting in a reduction in the incidence of post-stroke pneumonia in a chronic stage. The stroke must be a cause of aspiration pneumonia.

State of the art in aspiration assessment and the idea of a new non invasive predictive test for the risk of aspiration in stroke

BACKGROUND

Dysphagia is a common but severe complication in acute stroke. New bedside tests are necessary to assess the risk of aspiration and avoid unnecessary alimentary restrictions but they must be completed by evaluated instruments.

OBJECTIVE

We evaluated the prognostic validity of the recognition of forms (rf) test related to the assessment by speech and language therapists (SLT).

DESIGN

Double blinded screening tests.

SETTING

Geriatric department of general hospital.

SUBJECTS

50 patients with acute stroke admitted consecutively.

METHODS

All patients were assessed by SLT, mini mental status test, short test for assessing deficits of memory and attention and abilities of daily living-test. The rf-test was performed twice with a two week interval.

RESULTS

Assessment by SLT demonstrated aspiration in 29 of 50 patients. 18 patients failed the rf-test, giving a specificity of 90% (positive predictive value 89%), a sensitivity of 55% (negative predictive value 59%). 5 of 7 patients with aspiration pneumonia failed the test. Test-retest-correlation was 0,827. Performance in the rf-test was related significantly to results of the activities of daily living-test.

CONCLUSIONS

Bedside tests to exclude aspiration in patients with acute stroke are necessary. No test so far combines high sensitivity with acceptable specificity. Compared to other bedside tests the rf-test has a high specificity while sensitivity is low. On behalf of good predictivity rf-test may be an interesting supplement to swallow tests in case of stroke and seems to be a candidate for more extended studies.

Hypoxaemia and stroke

The topic of hypoxaemia after stroke was last reviewed in this journal in 2001. Since then a lot of new information on the subject has been published, and while some questions have been resolved, new problems have emerged. This article discusses new research in the light of what is already known and outlines areas of persisting uncertainty.

Time and time-frequency characterization of dual-axis swallowing accelerometry signals

Single-axis swallowing accelerometry has shown potential as a non-invasive clinical swallowing assessment tool. Previous swallowing accelerometry research has focused exclusively on the anterior-posterior vibration detected on the surface of the neck. However, hyolaryngeal motion during pharyngeal swallowing occurs in both the anterior-posterior and superior-inferior directions, suggesting that dual-axis accelerometry may be worthy of investigation. With this motivation, the present paper provides a characterization of dual-axis swallowing accelerometry signals from healthy adults in the time and time-frequency domains. Time-domain analysis revealed that signals in the two axes exhibited different probability density functions, and minimal cross-correlation and mutual information. Time-frequency analysis highlighted inter-axis dissimilarities in the scalograms, pseudo-spectra and temporal evolution of low- and high-frequency content. Therefore, it was concluded that the two axes contain different information about swallowing and that the superior-inferior axis should be further investigated in future swallowing accelerometry studies.

Dysphagia: implications for older people

This review opens with an outline definition of dysphagia, its causes, and why it is vital that people involved in the health care of older people should be aware of it. A brief consideration of prevalence is followed by an overview of assessment options. We conclude with a section on management.