Richard E. Ellis

Comparative Review of Techniques for Recording Respiratory Events at Rest and during Deglutition

Abstract. The coordination between swallowing and respiration is essential for safe feeding, and noninvasive feeding-respiratory instrumentation has been used in feeding and dysphagia assessment. Sometimes there are differences of interpretation of the data produced by the various respiratory monitoring techniques, some of which may be inappropriate for observing the rapid respiratory events associated with deglutition. Following a review of each of the main techniques employed for recording resting, pre-feeding, feeding, and post-feeding respiration on different subject groups (infants, children, and adults), a critical comparison of the methods is illustrated by simultaneous recordings from various respiratory transducers. As a result, a minimal combination of instruments is recommended which can provide the necessary respiratory information for routine feeding assessments in a clinical environment.

The synchronization of respiration and swallow sounds with videofluoroscopy during swallowing

Simultaneous recording of adult subjects sipping small amounts of fluid from a cup have been obtained by videofluoroscopy together with feeding respiratory patterns and swallow sounds from the Exeter Dysphagia Assessment Technique (EDAT). These allowed visual representations of respiration and swallow sounds to be superimposed on a videofluoroscopy recording using a split-screen technique. Sequentially numbered, 1/50 sec, half-frame photographic prints were examined and schematic drawings of the relevant radiographs were made. These were superimposed on to the actual EDAT printed chart of the same swallow event, theri exact time relationship with respiration and cervical swallow sounds being preserved. The results allow events in the barium videofluoroscopy to be related to events in the feeding respiratory pattern and swallow sounds recorded by EDAT.

Structural Analysis of Glycosaminoglycans and Proteoglycans by Means of Raman Microspectrometry

Raman spectra have been determined for hyaluronan, chondroitin-4-sulfate, chondroitin-6-sulfate, aggrecan monomers and aggregates. The nature of the saccharides and the pattern of sulfation can be discerned. There were only small spectral changes with pH and ionic composition. Differences between hydroxyl vibrations, bulk water and solution conditions are shown. The spectrum of aggrecan is dominated by chondroitin sulfate contribution. The sulfation pattern and ratio of protein to glycosaminoglycan and the secondary structure of the core protein were determined.

Non-invasive assessment of swallowing and respiration in Parkinson's disease.

Abstract Oro-pharyngeal dysphagia is well recognised but often underestimated in people with Parkinsons disease. Asymptomatic patients may fail to receive timely advice or therapy, thus placing them at risk. The aim of this study was to determine whether subclinical abnormalities in swallowing and discrete changes in function such as those produced by prompting can be detected by non-invasive methods. We examined 12 people with idiopathic Parkinsons disease and 14 elderly comparison subjects. Five components of respiratory synchronisation and swalowing efficiency were monitored using the Exeter Dysphagia Assessment Technique. Ten feeding trials were administered under standard quiet conditions. The patients were then restudied using verbal prompts when the spoon was presented to the mouth. The duration of two oro-pharyngeal events and the frequency of respiratory variables were compared for unrelated and related samples. Results showed the oral and pharyngeal parts of the swallow to be significantly slower in those with Parkinsons disease. These patients required significantly more swallows to clear a 5-ml bolus, and fewer swallows were followed by expiration. When the patients were verbally prompted, there was a significant reduction in the duration of the oral part. This study demonstrates that non-invasive methods can be used to detect subclinical difficulties with swallowing amongst a group of asymptomatic patients with PD and that these methods are sensitive to small changes in function produced by a verbal cue.

Aspiration with Dysphagia: the Interaction Between Oropharyngeal and Respiratory Impairments

AbstractIndividuals with neurodisability and dysphagia often aspirate food because of oropharyngeal impairments and poor control of respiration. This study explored the interaction between these factors in 32 participants aged 3–33 years. Each person underwent a modified barium swallow study, during which respiration was recorded and displayed simultaneously on the video screen, in terms of inspiration, expiration, and velocity of airflow (TV data). The duration of time that material remained in the pharynx before the swallow (either because of pharyngeal delay or residue from the previous swallow) was called the pharyngeal dwell time (PDT). The mean PDT of the 5 slowest swallows for each participant was calculated for both liquids and thick purees. The proportions of time spent in inspiration and expiration during the PDT in seconds and a score representing the abnormality of inspiration, including its frequency and velocity, were recorded. The volume of material in the pharynx prior to these swallows was also estimated. Twelve participants aspirated liquids and 3 of the 12 also aspirated thick purees. PDTs were longer among aspirators (6.2 s) than nonaspirators (2.4 s) when consuming liquids. Also, the percentage of the PDT spent in inspiration was greater among aspirators than nonaspirators when taking liquids (31% vs. 11%) or thick purees (35% vs. 14%). During the PDT, aspirators showed more abnormal respiratory patterns for liquids but not for purees. There were no differences in the volumes of liquid or puree in the pharynx before the swallow between aspirators and nonaspirators. A plot of the PDT against a combined respiratory impairment score (i.e., percentage of the PDT spent in inspiration and respiratory abnormality) predicted aspirators with a sensitivity of 83% and specificity of 95%. Aspiration results from oropharyngeal impairments with inadequate respiratory integration. Further research is needed to investigate whether intervention to improve respiratory control can reduce aspiration in people with dysphagia.

Air swallowing in Rett syndrome

The possible causes of excessive swallowing of air leading to bloating, which is common in Rett syndrome (RS), were investigated during feeding and at rest. Seven individuals with RS aged between 4 and 33 years (three with air bloat) underwent feeding videoflouroscopy and concurrent respiration monitoring. The results were compared with a randomly selected group of 11 individuals, aged between 2 and 16 years, with quadriplegic cerebral palsy and feeding problems, some of whom had mild air bloat. All individuals from both groups had isolated pharyngeal swallows and several mouth breathed; this may account for some air swallowing but not the severe air bloat characteristic of RS. Thirty‐three individuals with RS aged between 3 and 44 years were monitored for nasal respiration, chest movements, swallowing, and vocal cord position at rest (between feeding). Twenty had air bloat, 17 of whom swallowed air during breath‐holding in the same way, and three gulped air during hyperventilation. Of the 13 without air bloat, eight did not have recurrent breath‐holding and five did, but without concurrent air swallowing. Several methods for reducing air swallowing in apnoea were investigated. The most successful was a dummy with an air leak, but this was poorly tolerated and could only be used for short periods of time. Apnoeas and air bloat are often worse when individuals are distressed and may in some individuals be reduced by anxiolytic medications.

Respiration patterns during feeding in Rett syndrome

Feeding problems are common in Rett syndrome in which there are characteristic oropharyngeal abnormalities. This study investigated the ways in which individuals regulated their respiration accordingly, and how this affected their overall feeding ability. Respiration during feeding was studied in 28 individuals, recording nasal airflow, chest and abdominal movements, and swallow sounds. Time to first swallow was defined as that between introduction of liquid/solid on a spoon and the first swallow. Six individuals also had videofluoroscopy with simultaneous respiration monitoring. Results indicated different respiratory patterns according to the time to first swallow and neurological status; the amount of time spent in apnoea was particularly important. Videofluoroscopy showed that apnoeas occurred most often when liquid was delayed in the pharynx, but this could be overcome in subjects with a lower level of disability. The carers estimate of the time for feeding was significantly related to the time spent in apnoea with liquids.

Dysphagia following strokes: Clinical observations of swallowing rehabilitation employing Palatal Training Appliances

A retrospective study was undertaken to evaluate the progress of a group of dysphagic stroke patients for whom a dental prosthesis the Palatal Training Appliance (PTA), was used in the active rehabilitation of the swallowing mechanism. Patients selected were those who had sustained a stroke uncomplicated by other neurological illness, during one 12-month period, and whose dysphagia caused anxiety to the medical staff in the hospital ward. Thirty severely dysphagic stroke patients satisfied these criteria. The study recorded the duration and type of supplementary feeding required during hospitalization. Thirteen patients had evidence of aspiration before the PTA was fitted and 5 afterwards. Seven patients died, but only 1 was recorded as having a febrile illness which may have contributed to the death. At discharge, which averaged 10 weeks after admission, 22 of the 23 survivors were taking an adequate oral diet. It was also noted that almost half of the patients who wore dentures before the cerebrovascular event were unable to control them afterwards, adding to their neurological swallowing difficulties. The fitting of a PTA and correction of unstable dentures appeared to help both motivation and function. The results show an improvement in the rehabilitation of oral feeding compared with previous reports by other authors, who did not use the dental appliance. There did not appear to be any medical contraindication to its use.

Dysphagia in cerebral palsy: A comparative study of the exeter dysphagia assesment technique and a multidisciplinary assessment

Eighteen children with cerebral palsy in a special school, most of whom had feeding difficulties, were studied to compare the diagnostic value of the Exeter Dysphagia Assessment Technique (EDAT) with an exhaustive clinical assessment undertaken by a multidisciplinary team experienced in the diagnosis and treatment of dysphagia of neurological origin. Four feeding skills were assessed by each method independently, viz. anticipation, intraoral sensory perception, oral-motor efficiency, and pharyngeal triggering. Comparison of the two sets of results showed agreement in at least 78% of the assessed skills. The possible reasons for the few discrepancies are discussed. The noninvasive EDAT equipment was easy to use with the children, who had a range of type and severity of cerebral palsy. The test was undertaken in their familiar surroundings and took 15 to 20 min per child. Interpretation of the results showed that EDAT provided a rapid, reliable diagnostic aid which assisted in the assessment of the degree of feeding impairment within each of the four feeding skills tested.

Ultrasonographic study of sucking and swallowing by newborn infants.

SIRWeber and colleagues (DMCN, 28, 19-24) included in their results on bottle-fed babies a trace (their Fig. 2) drawn from a video screen showing suck-swallow cycles and a respiratory trace recorded from a Graseby Dynamics Apnoea Alarm. Commenting on the co-ordination of swallowing and breathing, the authors state: ‘In some of the babies the swallows occurred consistently in the end-expiratory pause (between expiration and inspiration). This was noted particularly in fourand five-day-old babies. In others, notably babies at two days of age, the breath was held during either inspiration or expiration, in association with a swallowing motion’. In our series of observations on bottle-fed babies, made on a much larger sample than that reported by Weber et al. and using different techniques to record sucking, swallowing and respiration, we have found that the pattern for two-day-old babies is commonly a form which we have called ‘immature’. It later develops, over about five to eight days, into a more ‘mature’ pattern. We were disturbed to find that the patterns we had observed over many measurements did not agree with those of Weber et al. In particular, our recordings show that the swallow of a mature infant is almost always preceded by an inspiration and followed by an expiration. In those cases when swallowing occurs on expiration, the expiratory flow is arrested as a swallow takes place and then ccntinues before an inspiration. We have no record, from over 100 recordings, of an infant swallowing at end-expiration. To confirm our findings we have Fig. 1. Signals from three transducers recorded simultaneously from eight-day-old baby during resting respiration. Upper trace: thermistor anemometer held at naris. Centre trace: pressure drop across naris, indicating direction of nasal airflow. Bottom trace: Graseby Apnoea Monitor output (E = expiration, I = inspiration). Difference in height of anemometer trace is partly due to inhaled air more easily avoiding the transducer.