Esophago/pharyngo/laryngeal interrelationships: airway protection mechanisms

Mandibular advancement impairs swallowing ability more than head extension but less than mouth opening in the supine position

Mandibular advancement in the supine position may influence swallowing during dental treatment under intravenous sedation. This study investigated the influence of mandibular advancement in the supine position on swallowing ability, compared with head extension and mouth opening. The water swallowing test was performed in 13 healthy, awake, supine, adult subjects under four head and mandibular positions. An electromyogram of the suprahyoid muscles was recorded; the duration and peak amplitude were examined. A greater volume of water remained in the mouth during mouth opening and mandibular advancement relative to the neutral position; the volume in the mandibular advancement position was larger and smaller than that in the head extension position and during mouth opening, respectively. The duration of the electromyogram in the head extension position was longer than that in the mandibular advancement position, without differences in the amplitude. Thus, swallowing ability in the supine position was more impaired with mandibular advancement, relative to neutral and head extension positions, but less than that observed with mouth opening. Although unconfirmed by electromyogram, our findings suggest that head extension might improve airway patency by reducing the impairment of swallowing ability compared with mandibular advancement.

Short-Term Effects of Cold Liquids on the Pharyngeal Swallow in Preterm Infants with Dysphagia: A Pilot Study

Cold stimulation reduces airway compromise in adults with dysphagia. However, there is no sufficient evidence to support its use in the pediatric population. The primary goal of this pilot study is to assess the effect of cold liquid on the pharyngeal swallow mechanism in preterm infants with dysphagia. We hypothesized that thermal stimulation from cold liquid will decrease the risk of airway compromise in dysphagic preterm infants. Nine preterm infants with clinical symptoms of dysphagia were included. Video fluoroscopic swallow studies were used to assess the swallowing mechanism of each participant. The occurrence of swallow dysfunctions under room temperature liquid swallows (RTS) vs. short period cold liquid swallows (CS) was compared. Paired t test was used to test significance. The occurrence of deep penetration (p = 0.007) and aspiration (p = 0.002) decreased significantly in the CS condition compared with the RTS condition. There was a trend of less nasopharyngeal reflux with CS but did not reach statistical significance (p = 0.084). No differences were noted for mild penetration (p = 0.824). CS reduced airway compromise in dysphagic preterm infants compared to RTS. These data provide important information regarding the immediate effects of CS on pharyngeal swallowing in preterm infants with dysphagia. However, further investigation regarding its sustained effects is required before introducing to clinical practice.

The feasibility of office-based propofol sedation for dental care in patients with intellectual disability by sedation practitioners

BACKGROUND

The quality of oral health care for intellectually disabled patients is a significant challenge due to behavioral issues. Intravenous propofol sedation may be useful to relieve the anxiety and fear, and make dental procedures more acceptable. The aim of this study was to evaluate the safety and effectiveness of propofol sedation, by trained nonmedical sedation practitioners, during dental treatments in an office-based setting.

METHODS

Intellectually disabled patients (124) were subjected to restorative dental procedures and moderately sedated using intravenous propofol. Vital signs, cooperation of the patient, and sedation depth were continuously assessed.

RESULTS

Propofol sedation was effective for dental treatment. All procedures resulted in a sufficient level of sedation without moderate or severe complications.

CONCLUSION

Propofol sedation can be safely and effectively performed in an office-based setting by sedation practitioners, who have experience in propofol sedation and are trained in the care of patients with disabilities.

Aspirating and Nonaspirating Swallow Sounds in Children

Background:

Cervical auscultation (CA) may be used to complement feeding/swallowing evaluations when assessing for aspiration. There are no published pediatric studies that compare the properties of sounds between aspirating and nonaspirating swallows.

Aim:

To establish acoustic and perceptual profiles of aspirating and nonaspirating swallow sounds and determine if a difference exists between these 2 swallowing types.

Methods:

Aspiration sound clips were obtained from recordings using CA simultaneously undertaken with videofluoroscopic swallow study. Aspiration was determined using the Penetration-Aspiration Scale. The presence of perceptual swallow/breath parameters was rated by 2 speech pathologists who were blinded to the type of swallow. Acoustic data between groups were compared using Mann Whitney U-tests, while perceptual differences were determined by a test of 2 proportions. Combinations of perceptual parameters of 50 swallows (27 aspiration, 23 no aspiration) from 47 children (57% male) were statistically analyzed using area under a receiver operating characteristic (aROC), sensitivity, specificity, and positive and negative predictive values to determine predictors of aspirating swallows.

Results:

The combination of post-swallow presence of wet breathing and wheeze and absence of GRS and normal breathing was the best predictor of aspiration (aROC = 0.82, 95% CI, 0.70-0.94). There were no significant differences between these 2 swallow types for peak frequency, duration, and peak amplitude.

Conclusion:

Our pilot study has shown that certain characteristics of swallow obtained using CA may be useful in the prediction of aspiration. However, further research comparing the acoustic swallowing sound profiles of normal children to children with dysphagia (who are aspirating) on a larger scale is required.

Both head extension and mouth opening impair the ability to swallow in the supine position

Head position and mouth opening in the supine position may impair the ability to swallow. If this does occur, it would lead to retention of intra-oral fluids during dental treatment, which would lead to stimulation of the cough reflex. This study was conducted to investigate how head position and mouth opening affect swallowing ability. The water swallowing test was performed in 13 healthy adult subjects in the supine position. The subjects were asked to swallow 10 mL of water that was injected into the mouth in a single attempt. After swallowing, the residual intra-oral water was suctioned and its volume was measured. An electromyogram (EMG) of the suprahyoid (SH) muscles was also recorded during the test. The duration of SH muscle activity and peak amplitude of SH EMG were examined. The water swallowing test was performed under three head positions (neutral, extended and flexed) and four mouth opening patterns (interincisal distances of 0, 20, 30 and 40 mm). The wider the subject opened the mouth, the more the water remained in the mouth after swallowing. The residual volume of water was more in the extended position compared with that in the neutral and flexed positions. Peak amplitude of SH EMG decreased with mouth opening. Duration of SH muscle activity was longer in the extended position than in the neutral and flexed positions. Head extension and mouth opening can induce difficulty in swallowing in the supine position by extending the duration of SH muscle activity while reducing its intensity.

Paced glottic closure for controlling aspiration pneumonia in patients with neurologic deficits of various causes

OBJECTIVES

We undertook to determine whether paced vocal fold adduction can check aspiration in patients with various neurologic conditions.

METHODS

Five patients with fluoroscopically documented aspiration and repeated pneumonias were enrolled. Two previously reported patients with hemispheric stroke were compared to 3 additional subjects with brain stem-basal ganglia and cerebellar stroke, cerebral palsy, and multiple sclerosis. A modified Vocare stimulator was implanted subcutaneously and linked to the ipsilateral recurrent laryngeal nerve via perineural electrodes. Vocal fold adduction and glottic closure were effected with pulse trains (42 Hz; 1.2 mA; 188 to 560 micros) and recorded with Enhanced Image J. Fluoroscopy results with and without stimulation were assessed by 2 independent blinded reviewers. Pneumonia rates were compared before, during, and after the 6- to 12-month enrollment periods.

RESULTS

There was statistically significant vocal fold adduction (p < 0.05) for all patients, further verified with bolus arrest (p < 0.05 for thin liquids, thick liquids, and puree depending on the speech-language pathologist). Pneumonia was prevented in 4 of the 5 patients during enrollment. In the fifth patient, who had brain stem-basal ganglia and cerebellar stroke, we were unable to completely seal the glottis and open the cricopharyngeus enough to handle his secretions.

CONCLUSIONS

Vocal fold pacing for aspiration pneumonia from a variety of neurologic insults appears to be appropriate as long as the glottis can be sealed. It is not sufficient when the cricopharyngeus must be independently opened.

Neuronal activation in the medulla oblongata during selective elicitation of the laryngeal adductor response

Swallow and cough are complex motor patterns elicited by rapid and intense electrical stimulation of the internal branch of the superior laryngeal nerve (ISLN). The laryngeal adductor response (LAR) includes only a laryngeal response, is elicited by single stimuli to the ISLN, and is thought to represent the brain stem pathway involved in laryngospasm. To identify which regions in the medulla are activated during elicitation of the LAR alone, single electrical stimuli were presented once every 2 s to the ISLN. Two groups of five cats each were studied; an experimental group with unilateral ISLN stimulation at 0.5 Hz and a surgical control group. Three additional cats were studied to evaluate whether other oral, pharyngeal, or respiratory muscles were activated during ISLN stimulation eliciting LAR. We quantified < or = 22 sections for each of 14 structures in the medulla to determine if regions had increased Fos-like immunoreactive neurons in the experimental group. Significant increases (P < 0.0033) occurred with unilateral ISLN stimulation in the interstitial subnucleus, the ventrolateral subnucleus, the commissural subnucleus of the nucleus tractus solitarius, the lateral tegmental field of the reticular formation, the area postrema, and the nucleus ambiguus. Neither the dorsal motor nucleus of the vagus, usually active for swallow, nor the nucleus retroambiguus, retrofacial nucleus, and the lateral reticular nucleus, usually active for cough, were active with elicitation of the laryngeal adductor response alone. The results demonstrate that the laryngeal adductor pathway is contained within the broader pathways for cough and swallow in the medulla.

Tratamento cirúrgico para aspiração

Introdução: Quando o mecanismo protetor da laringe está comprometido, o paciente pode apresentar aspiração traqueal, com graves complicações pulmonares. Objetivo: Relatar 15 casos de tratamento cirúrgico para o controle da aspiração crônica, incluindo as técnicas cirúrgicas empregadas, seus resultados e complicações. Forma de estudo: Avaliação retrospectiva. Material e método: No período de 1997 a 2000, 15 pacientes foram submetidos à cirurgia para controle da aspiração, na AACD - São Paulo/SP. As técnicas cirúrgicas empregadas foram classificadas em: oclusão laríngea supraglótica; oclusão laríngea glótica; oclusão subglótica ou separação laringotraqueal. Foi avaliado o perfil dos pacientes em relação a sexo, idade, etiologia de base, traqueotomia prévia, via preferencial de alimentação, redução das infecções pulmonares, tempo de seguimento pós-operatório e complicações. Resultados: Oito pacientes eram do sexo masculino e sete do feminino, com idade média de nove anos e dois meses. A doença etiológica de base mais comum foi a encefalopatia crônica. Dez pacientes foram submetidos à traqueotomia previamente à cirurgia. Nove pacientes apresentaram, no pós-operatório, dieta via oral de pelo menos 50% do volume requerido. Os 15 pacientes evoluíram com diminuição no número e na gravidade das infecções pulmonares. O tempo de seguimento pós-operatório variou de quatro a 36 meses. Um paciente evoluiu com deiscência parcial na técnica de oclusão laríngea supraglótica. Conclusão: A cirurgia para controle da aspiração traqueal, nas três técnicas utilizadas, foi eficaz para prevenção da aspiração, refletindo na melhora clínica e na qualidade de vida dos pacientes.