Intubation granuloma is a benign growth of granulation tissue in the larynx or trachea, which arises from tissue trauma due to endotracheal intubation. This medical condition is described as a common late complication of tracheal intubation, specifically caused by irritation to the mucosal tissue of the airway during insertion or removal of the patient's intubation tube. Endotracheal intubation is a common medical procedure, performed to assist patient ventilation and protect the airway. However, prolonged endotracheal intubation, the use of inappropriate intubation equipment, or improper airway manipulation by the medical team may directly lead to mechanical trauma, resulting in laryngeal granuloma formation in the subglottis of the larynx. Diagnosis of intubation granulomas are achieved through identifying proliferating tissues in the vocal folds via laryngoscopy.
Primary treatment for intubation granulomas tends to involve surgical excision of the granuloma. However, single treatment methods alone often result in high incidences of recurrence, hence combined therapy is suggested. Secondary methods involve low dose radiotherapy and corticosteroid drug treatments. For extreme cases of refractory granulomas, in which the aforementioned treatment methods all prove ineffective, botulinum toxin injections and oral zinc sulfate treatments are administered. Other significant risk factors are associated with intubation granuloma formation as well, such as a patient's age, sex, intubation history and pre-existing medical conditions, which indirectly predispose certain patients to intubation-related injuries.
Signs and symptoms Persistent sore throat, hoarseness, and vocal fatigue following intubation procedures are common symptoms of intubation granuloma, and patients may report mild discomfort associated with the sensation of a rough foreign body lodged in the back of the throat. These symptoms often provoke observable clinical signs such as frequent coughing, throat-clearing, and hoarseness accompanied by dysphonia, reduced voice quality and restricted vocal range. Severe intubation granulomas cause pharyngitis and pain upon pressed phonation, coughing or throat clearing. In some cases, the patient may even experience dyspnea, or shortness of breath due to airway obstruction by the granuloma. However, since granulomas and other vocal cord polyps may take weeks or months to develop, intubation granulomas may sometimes be clinically evident only when the aforementioned symptoms persist for, or reappear after a longer period of time post-extubation. Initial symptoms may also be overlooked as they coincide with typical side-effects of intubation. Case reports of patients diagnosed and treated for intubation granulomas concur with this observation, as the diagnosis is often made weeks or months after the patient is extubated.
Causes Tracheal and laryngeal trauma leading to an intubation granuloma are caused by traumas during the intubation processes, directly resulting from technical circumstances such as specifications of the breathing tube equipment, method of insertion, and intubation duration.Intubation duration Statistically, patients intubated for more than 48 hours will experience some form of laryngeal injury attributed to intubation, and approximately half of the injuries will result in the development of granulation tissue in the vocal fold. While there is no consensus on the maximal permissible duration of safe endotracheal intubation, the risk of trauma-related laryngeal granuloma formation increases significantly with prolonged durations of tracheal intubation. However, there are also studies which have not found statistically significant correlations between prolonged intubation duration with the degree of laryngeal injury, and intubation granuloma cases have also been reported in patients who have been intubated for only a few hours. Intubation tube diameter Appropriate intubation tube sizes are defined as those small enough to minimise risks of mucosal trauma while large enough to maintain adequate ventilation. This is especially important in the field of pediatrics, where the development of a child's trachea may vary according to age. Age-based calculations of appropriately sized intubation tubes are conducted in accordance with the Khine formula, which are based on internal diameters. Unfortunately, these formulas do not account for variances in outer diameter and cuff dimensions, which may result in varying tube sizes. Alternatively, height-based calculations are also available. According to PALS (2010) guidelines, the use of length-based resuscitation tapes has proven to be more accurate than age-based estimates of endotracheal intubation tubes. Cuff pressure The addition of an endotracheal tube cuff decreases the likelihood of selecting oversized breathing tubes for the patient, while also preventing microaspiration and the leakage of respiratory gases during intubation. However, hyperinflation of the cuff places excessive pressure on the tracheal wall, causing trauma or ischaemia to nearby tissue and hence increasing the risk of granuloma formation. Cuff pressures can be monitored during endotracheal intubation via manometers to prevent nitrous oxide induced hyperinflation. General guidelines suggest that cuff pressure should be maintained between 20 and 30 cm to minimise risks of intubation-related trauma.
Diagnosis Intubation granulomas are most commonly presented in the form of red or pale spherical lesions in the subglottis of the larynx and may be defined as protruding, inflamed fibrovascular tissue. While it is possible for intubation granulomas to form in both the larynx or trachea, they are most characteristically located in the posterior third aspect of the larynx, stemming from the posterior vocal fold directly above the vocal process cartilage. Diagnosis of granulomas are confirmed via videolaryngostroboscopy and the electromyography by identifying proliferating tissue originating in the vocal process. Furthermore, granuloma severity can be determined using screening images of laryngoscopy and graded in accordance to Farwell's grading system.
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