Автор: Putnikov
создано: 14.01.2010 09:23
Patients with a tracheostomy
http://emedicine.medscape.com/article/324096-overview
The frequency of aspiration in patients with a tracheostomy is 50-83%. The tracheostomy tube affects airway protection and swallowing in many ways. It impairs the glottic closure reflex, reduces subglottic pressure and laryngeal elevation, impairs hypopharyngeal and laryngeal sensation, and leads to disuse muscle atrophy.
Tracheostomy alters the essence of normal respiratory flow by diverting air through the neck instead of the pharynx, especially when an inflated tracheostomy tube cuff is present. The previous belief that an inflated tracheostomy tube cuff prevents aspiration of food has been refuted. An inflated cuff causes secretions to stagnate and collect above it, and these secretions can trickle down past the cuff and potentially lead to infection. Increasing the pressure of the cuff may lead to malacia, stenosis, fistula of the tracheal wall, or dragging of the cuff on the larynx as the larynx elevates during a swallow (laryngeal excursion).
Subglottic airway pressure is disrupted in patients with open tracheostomy tubes. The expiratory phase is shortened because the function of the normal vocal folds to maintain lung volumes throughout the physiologic prolongation of the expiratory phase is impaired. Furthermore, reduced subglottic pressure precludes effective coughing. Superior and anterior laryngeal excursion during swallowing facilitates vertical closure of the laryngeal vestibule, assisting in airway protection and opening of the upper esophageal sphincter. The tracheostomy tube may attach the larynx to the surrounding neck tissue, anchoring it in position and reducing laryngeal elevation.
The tracheostomy desensitizes laryngeal and hypopharyngeal receptors, delaying onset of the laryngeal adductor reflex response and leading to aspiration. The sensory response, and hence the organization of the swallowing mechanism, can be improved by restoring the transglottic airflow by downsizing the tracheostomy tube, placing a fenestrated tube, or occluding the tracheostomy tube with a cap or with a 1-way speaking valve.
Endotracheal intubation also affects swallowing function, directly and indirectly. The direct effect of the endotracheal tube on laryngeal structures is caused by laryngeal trauma, which manifests as vocal-fold and supraglottic edema, granulation tissue in the posterior larynx, subluxation of 1 or both arytenoid cartilages, and permanent or temporary palsy of the recurrent laryngeal nerve. Supraglottic and glottic edema reduces the patient's ability to sense the presence of secretions in the larynx or hypopharynx, which in turn can inhibit the timely triggering of the pharyngeal swallow response, causing aspiration.
Indirect effects on swallowing caused by endotracheal intubation relate to the coordination required between respiration and the swallowing function. An increased respiratory rate in patients with suboptimal oxygenation can disrupt the regular swallowing and respiration pattern and predispose the patient to aspiration of saliva and secretions. For example, continuous, positive airway pressure delays the latency of the swallow response and reduces the number of swallows, because it alters the peripheral sensory receptors that assist with the triggering of a pharyngeal swallow.
To restore glottic closure, subglottic pressures, and transglottic airflow, 1-way speaking valves are used. The value of the occlusion of the tracheostomy tube may be related to the provision of a closed aerodigestive tract, which enables the patient to effectively react to aspiration. Other important benefits include improved communication, improved olfaction, and assistance with decannulation. Restoration of glottic function can also be accomplished by downsizing the standard cuffed tracheostomy tube toward stepwise decannulation.
Patients receiving mechanical ventilation often cannot control the duration of inspiratory and expiratory airflow. Therefore, ventilator settings, such as tidal volume and flow rate, may need to be adjusted during meals. (Tidal volume may need to be increased, and flow rate may need to be reduced.) The patient may have to relearn the inspiratory and expiratory phases of the breathing cycle for optimal coordination with swallowing.
Stroke пациенты обычно попадают в stroke-центры,т.е специализированные ICU,занимающиеся только такими пациентами.Частота трахеостомий в таких центрах значительно ниже,чем в травма ICU или нейрохирургических ICU.Максимальные усилия прилагаются к ранней диагностике ишемического инсульта и раннему тромболизису (в течение 3 часов после появления симптомов).Что позволяет практически полностью восстановить утраченные функции.В общем и целом,не существует никаких гайдлайнс по поводу того,когда и кому делать трахеостомию.Все зависит от степени агрессивности данного конкретного центра. MRI обладает самой высоской сенситивносью и специфичностью в диагностике инсульта.KTне позволяет раннюю диагностику stroke.
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Re: Без контроля 
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Re: Без контроля 
Re: Без контроля