Mechanisms of airway protection during retching, vomiting, and swallowing

Abstract

We investigated the mechanisms of airway protection and bolus transport during retching and vomiting by recording responses of the pharyngeal, laryngeal, and hyoid muscles and comparing them with responses during swallowing and responses of the gastrointestinal tract. Five dogs were chronically instrumented with electrodes on the striated muscles and strain gauges on smooth muscles. Retching and vomiting were stimulated by apomorphine (5-10 ug/kg iv). During retching, the hyoid and thyroid descending and laryngeal abductor muscles were activated; between retches, the hyoid, thyroid, and pharyngeal elevating, and laryngeal adductor muscles were activated. Vomiting always occurred during the ascending phase of retching and consisted of three sequential phases of hyoid and pharyngeal muscle activation culminating in simultaneous activation of all recorded elevating and descending laryngeal, hyoid, and pharyngeal muscles. Retrograde activation of esophagus and pharyngeal muscles occurred during the later phases, and laryngeal adductor was maximally activated in all phases of the vomit. During swallowing, the laryngeal adductor activation was followed immediately by brief activation of the laryngeal abductor. We concluded that retching functions to mix gastric contents with refluxed intestinal secretions and to impart an orad momentum to the bolus before vomiting. During retches, the airway is protected by glottal closure, and between retches, it is protected by ascent of the larynx and closure of the upper esophageal sphincter. The airway is protected by maximum glottal closure during vomiting. During swallowing, the airway is protected by laryngeal elevation and glottal closure followed by brief opening of the glottis, which may release subglottal pressure expelling material from the laryngeal vestibule.

Neurogenesis of cough, other airway defensive behaviors and breathing: A holarchical system?

“…That is, what is the makeup of the control system that ensures that multiple behaviors will not be expressed simultaneously; resulting in mechanically inappropriate motor acts? For example, in awake animals behaviors that include laryngeal abduction do not occur during vomiting under normal conditions (Lang et al, 2002). The identity of the regulatory mechanism preventing laryngeal abduction or the occurrence of behaviors that include dilation of the larynx during vomiting is unknown, but it is very important to prevent aspiration.…”

Digestive and respiratory tract motor responses associated with eructation

“…Aseptic techniques were used to implant recording devices on the muscles of the digestive and respiratory tracts in 10 mixed-breed dogs (17-25 kg body wt) of either sex, as described previously (14,17). Recording devices were placed on appropriate muscles in the thorax, abdomen, and cervical region during separate surgeries to minimize risk of infection and stress to the animals.…”

“…Strain gauge force transducers (n ϭ 6) were sewn onto the seromuscular layer of the gastric fundus, corpus, antrum, duodenum, jejunum, and ileum. The lead wires from these recording devices were brought out of the abdomen through a stainless steel cannula, as described previously (14,17).…”

“…A midline incision was placed on the ventral surface of the neck, and the esophageal, pharyngeal, laryngeal, and hyoid muscles were carefully exposed as described previously (14,17). Bipolar silver wire electrodes were sewn onto the mylohyoideus (MH, n ϭ 3), geniohyoideus (GH, n ϭ 5), thyrohyoideus (TH, n ϭ 10), hyopharyngeus (HP, n ϭ 4), hyoglossis (HG, n ϭ 3), stylopharyngeus (StP, n ϭ 3), thyropharyngeus (TP, n ϭ 9), cricopharyngeus (CP, n ϭ 10), esophagus (n ϭ 9), sternohyoideus (SH, n ϭ 3), sternothyroideus (STh, n ϭ 3), cricothyroideus (n ϭ 4), cricoaretynoideus dorsalis (n ϭ 3), thyroaretynoideus (TA, n ϭ 3), and esophagus (n ϭ 10).…”

Interação entre o grupamento parafacial/núcleo retrotrapezóide e a região de kölliker-fuse na modulação do padrão respiratório.

“…Outros padrões não respiratórios que recrutam os neurônios motores pós-inspiratórios seriam durantes os processos de defecação e vômitos (FUKUDA;FUKAI, 1986;LANG et al, 2002;MILLER, 1999).…”