Abstract: The overall aim of the present study was to evaluate demographic pattern of laryngo-tracheal stenosis following prolonged endotracheal intubation. Prolonged trans-laryngeal intubation is associated with increased laryngeal injury, glottic and sub-glottic stenosis, infectious complications and tracheal injury such as tracheomalacia and tracheal stenosis. Several studies assessing the laryngeal complications are available in Caucasoid populations. Minimal data is available in the literature related to Iran. It was a prospective analytical study in Otolaryngology- Head and Neck Surgery Department, Ahwaz Jondishapour University of Medical Sciences, from 2005 until 2007 (19 months) in Ahwaz, Iran. This is a prospective study of 98 patients (61 patients were male), who were intubated for more than 48 h in Imam Khomeini, Golestan and Razi Hospital critical care unit with different causes and were referred to Otolaryngology emergency ward with respiratory distress. All patients underwent laryngeal video endoscopy and laryngeal computed tomography scan by an otolaryngologist surgeon who was blinded to the intubation variables. Twenty five patients had been presented by laryngo-tracheal stenosis and the most common site of that was sub-glottic area (sixteen patients). Statistical analytic findings showed that from several factors (such as tube size (p = 0.088), skill of intubating doctor (consultant or registrar; p = 0.146), duration of intubation (p = 0.002) and emergency intubation (p = 0.240) only prolonged intubation (p = 0.002) was associated with higher incidence of laryngo-tracheal stenosis. In conclusion, Laryngo-tracheal stenosis after prolonged endotracheal intubation is directly associated with duration of intubation. The most common site of laryngeal stenosis was sub-glottic area.
INTRODUCTION
Prolonged trans-laryngeal intubation is associated with increased laryngeal injury, glottic and sub-glottic stenosis, infectious complications and tracheal injury such as tracheomalacia and tracheal stenosis (Cummings, 2005; Granja et al., 2002). Converting intubation to a tracheotomy also may facilitate suctioning, feeding and mobility; promote early return of speech and decrease the work of breathing (Granja et al., 2002). Meticulous surgical technique, aggressive treatment of postoperative infections and the use of the high-volume, low-pressure cuffed tube help minimize the risk of tracheal stenosis (Rajagopalan et al., 2002). Evidence suggests that the risk of long-term airway complications significantly increases with trans-laryngeal intubation beyond the tenth day (Granja et al., 2002; Panda et al., 1999). Tracheal stenosis and sub-glottic stenosis are complications predisposed by previous endotracheal tube intubation, high tracheostomy or cricothyroidotomy and trauma to the airway. Patients at increased risk for tracheal stenosis include children and patients tracheotomized for closed head trauma. While the indications for intubation are varied, it is commonly used for ventilatory assistance, relief of upper airway obstruction and to aid in tracheobronchial toileting.
With the advent of high volume low-pressure tubes, it is common for the patients to be ventilated through the endotracheal tube for up to three weeks. The complication of intubation depends on multiple factors and can also at times be a major source of morbidity to the patient during recovery. Laryngeal complications after prolonged intubations have varied incidence rates in the literature. Hoarseness of voice, cough, dysphagia, aspiration and stridor can develop after extubation, immediately. Laryngeal evaluation of such patients becomes necessary to assess the nature of airway injury. Common injuries following long-term intubation can manifest in the form of erythema, ulceration, granulomas, arytenoid dislocations (Cummings, 2005; Rangachari et al., 2006; Kastanos et al., 2000) sub-glottic stenosis and vocal fold immobility; (Rajagopalan et al., 2002; Panda et al., 1999). While several studies assessing the laryngeal complications are available in Caucasoid populations; minimal data is available in the literature related to Iran. Therefore we retrospectively evaluated the etiologic risk factors of laryngo-tracheal stenosis in patients after prolonged intubation to determine the association with risk factors. The medical ethics committee of the Otorhinolaryngology-Head and Neck surgery department approved the study and informed consent was obtained from all subjects. The most references recommended that the conversion from trans-laryngeal intubation to tracheotomy be made as early as possible to minimize the duration of trans-laryngeal intubation (Cummings, 2005; Hsu et al., 2005; Granja et al., 2002; Heffner, 2001; Valsh and Shorten, 1999).
MATERIALS AND METHODS
In this prospective analytical study 98 (sixty one patients were male) patients who were referred to ENT emergency wards of Imam Khomeini, Golestan and Razi University Hospitals with respiratory distress were included from April 2005 until March 2007. All ninety eight patients have age >20 years old, extubated at the intensive care unit of above named Hospitals after at least 48 h of intubation were included in the study. Laryngeal examination with a rigid 70° and direct laryngeal video-endoscopy was done for all patients. Subjects were evaluated by chief resident of otolaryngology ward who was blinded to the intubation variables using the 70° telescopes. Anesthesia (10% Lidocaine spray) was offered to patients with active gag reflexes. The tip of the rigid telescope was immersed in hot water to prevent fogging of the lens. With one hand holding the tongue of the subject, the examiner inserted the telescope through the oral cavity. A color video camera and color monitor were used for visual feedback. Using the image on the monitor, the examiner guided the telescope to view the laryngeal surface of the epiglottis, the anterior commissure, the subglottic area and the pyriform fossae. The images obtained on the color monitor were video recorded. Laryngeal computed tomography scan (CT scan) was done for all patients for evaluation of sub glottic stenosis. The association of laryngeal findings with demographic details along with intubation variables nature of intubation (emergency or elective), size of endotracheal tube, skill of intubating personnel (Consultant/Resident) and cuff pressure during the intubated period, total period of intubation were studied. The results were analyzed by using SPSS (version: 13) statistical software. Parametric (normally distributed) data were analyzed using t-test for group comparisons. Nonparametric (skewed) data were analyzed using Kruskal-Wallis test. Univariate correlation between presence of laryngeal complications and parametric variables was done using Spearman`s coefficient of correlation. Chi-square test was used to analyze datum and p value of (<0.05) was accepted as being statistically significant.
RESULTS AND DISCUSSION
Laryngeal abnormalities were seen in thirty six of the ninety eight patients during examination on post extubation period by ENT surgeon with helping laryngeal rigid endoscopy and laryngeal CT scan. At the end of laryngeal rigid endoscopy, physical examination and CT scan findings reveal that twenty five patients had laryngo-tracheal stenosis. Vocal cord granuloma was the most common feature in the set of abnormal findings on laryngeal rigid endoscopy in six patients; other abnormalities were arytenoids dislocation in three patients and unilateral vocal cord palsy in two patients. Figure 1 shows the laryngeal sequelae distribution among the patients under investigation. All of individual factors such as age, sex, height and weight had not any significant analytical relationship with laryngeal complication. Table 1 shows data regarding intubation variables and their association with the laryngeal sequelae on laryngeal endoscopy in patients. Multivariate and Univariate analysis of the intubation variables showed that between several factors include: larger endotracheal tube size (p = 0.088), skill of intubating doctor (consultant or registrar; p = 0.146), nature of intubation (Table 2), (elective or emergency; p = 0.240) and prolonged intubation (p = 0.002) (Table 3).
The presence of laryngeal complications (laryngo-tracheal stenosis) associated with the laryngeal rigid endoscopy and CT scan findings after extubation was related only to the duration of intubation significant factors (p = 0.001). The most common site of laryngeal involvement was sub-glottic stenosis. Twenty five patients had tracheolaryngeal stenosis, with laryngeal CT scan and endoscopy findings. In this study the most common site of laryngeal stenosis was sub-glottic area (sixteen patients).
Laryngeal injuries following intubation have a reported incidence from
60% to 90% and permanent sequelae are reported to be about 15% in the
world literature (Cummings, 2005; Rangachari et al., 2002). The
time to switch over from endotracheal tubes to tracheostomy is controversial
(Panda et al., 1999) Current data suggest that ventilation through
high volume low-pressure endotracheal tubes are the method of choice of
artificial airway up to 3 weeks (Hsu et al., 2005). The laryngeal
injuries can vary from mucosal injuries like vocal cord erythema, edema,
granulations and ulcerations to more permanent sequelae like vocal cord
palsy(Heffner, 2001) arytenoids dislocation (Cummings, 2005; Granja
et al., 2002) and sub-glottic stenosis (Kastanos et al., 2000;
Santos et al., 1999; Whited et al., 1994). In this study
vocal cords and the arytenoids were not the only components of the larynx
involved in injuries. There were patients with vocal cord paralysis, arytenoids
dislocations or tracheal and sub-glottic stenosis in this study population.
Laryngeal injuries are seen in patients intubated with larger size endotracheal
tube. The determination of tube size of an adult patient is usually based
on the physician`s assessment of neck morphology and external features
of the larynx. There is no standard formula to serve as a guide to appropriate
tube size. A size eight endotracheal tube is generally used for adults
and size 7 or 7.5 for small built adults. In this study the size of endotracheal
intubation tube had not any significant statistical relation with tracheolaryngeal
stenosis (p = 0.088) Kastanos et al., (2000) showed increased incidence
of laryngeal injuries with higher cuff pressures. In our study
population, 90% of the patients had a standard cuff pressure of 30 cm
H2O. The cuff restricts the flow of blood through the tracheal
tissues thus causing ischemic damage. The use of high-volume, low-pressure
endotracheal tubes are also a routine practice in this intensive care
unit. These tubes have a cuff with a large resting volume and diameter
and a thin compliant wall that allows a seal with the trachea to be achieved
without stretching its wall. This reduces the risk of injury to tracheal
tissues; thereby reducing the risk of significant cuff-induced complications
following prolonged intubation. The association of more laryngeal complications
with emergency intubations is an expected occurrence. Intubations done
in the emergency sitting have the disadvantages of less preparation, inadequate
patient sedation and less co-operation on the part of the patient that
can be responsible for higher occurrence of laryngeal injuries. In this
study the emergency intubating had not any significant statistical relation
with tracheolaryngeal stenosis (p = 0.240). The skill of the intubating
physician also plays an important role in the genesis of laryngeal injuries.
The residents and trainees with less skill and experience have comparatively
greater association with complications than the consultants. Use of appropriate
tube size and monitoring of duration of intubation is essential in the
prevention of laryngeal complications (p = 0.002). Only about 20% of the
patients had permanent sequelae. This study shows that, at the post extubation
period, duration of intubation was the only predictor of post extubation
laryngeal sequelae. Use of appropriate tube size and monitoring of duration
of intubation is of paramount importance. A systematic laryngeal examination
after extubation, whenever indicated, decreases the secondary sequelae
by initiating appropriate measures when necessary. It is highly suggested
to early otorhinolaryngology consultation for the patients who are intubated
in Intensive Care Unit (ICU) for any etiologies it seems to large analytical
studies with bigger cohorts are needed to define the role of medical disorders
and other parameters in producing laryngeal complications in patients
with prolonged intubation.
| Fig. 1: | Laryngeal sequelae distribution |
| Table 1: | Statistics intubation attributes |
| Table 2: | Intubation nature and laryngeal complication |
| Table 3: | Intubation duration and laryngeal complication |