Introduction
The delicate structures of the larynx can be compromised by innumerable causes[1]. One of them is the endotracheal intubation.
The endotracheal intubation allows to the ventilation assistance in anaesthetized
patients or under ventilation mechanics, being able to be of shortness or long duration.
The presence of pipes or nasotracheals in direct contact with the structures of the
aerial ways can provoke injuries of mucus, derive from, mainly, of traumatic and drawn
out intubations, the use of pipes of great bore and of the raised pressure in the
ballonet of probes[2].
The traumatic intubation can occur in emergency situations, that demand rapidity in
the access of the aerial ways, in the difficult exposition of glottis or when carried
through by professionals inexperienced[1]
[2].
The complications of the secondary aerial ways to the endotracheal intubation are
frequent, even so have diminished significantly in recent years. Many occur with light
symptoms and of short duration. However, in many cases the injuries are serious and
permanent, involving the structures of the larynx and the trachea, and demand surgery
correction[2]
[3].
The some complications have global incidence varying of 0% the 18%[4]
[5]. Prospective study, it found index of 63% of acute injuries of the larynx in patients
submitted to the orotracheal intubation and that they had been reversible in 30 days[6].
Due to configuration of glottis in “V”, the main injuries occur in the posterior portion
of the larynx, in the vocal processes, where the sounding lead meets in close contact
with the mucous, being able to result in ulceration of the region that involves the
epithelium of the interarytenoid mucous, healing with fibrosis and setting of the
arytenoids cartilages in the median line, simulating picture of bilateral paralysis
of the folds vocals[2].
Diverse types of larynx and windpipes, secondary injuries to the endotracheal intubation,
have been described[7]. Soon in the introduction of the cannula for it verbal via, during the attempts
of exposition of glottis with the laryngoscope, are described, extractions, injury
of lip, language and pharynx vocal lacerations in epiglottis, folds, esophagus and
trachea, hematomas and accession of vocal folds, displacement and strain of arytenoids
cartilages[8]. With the time complications occur as frostbite of mucous, stricture and granulomas[1]
[2]. In the pathophysiology of these injuries, the ischemia of the mucous is the common
denominator, particularly for the use of tracheal pipes of bigger diameter and for
the raised intracuff pressure[7].
The factors of risk for the endotracheal after-intubations complications are of three
types: factors related to the patient, related with the requirements technician to
reach and to keep the intubation, and factors related to medic[3].
Between the factors of risk related the patient include age, because the mucous larynx
if become more fragile with the age and are more susceptible injury[9], history of intubation and tobbaco[10].
Between the risk factors associates with conditions techniques to reach and to keep
the intubation met it drawn out duration of intubation (the risk of complications
increases with the duration of the intubation)[8]
[9], the size of endotracheal pipe (in particular sounding leads whose size is bigger
or equal the 8 they would result in more complications of what the sounding leads
lesser bore)[8]
[11] agitation of the patient (especially extubation-reintubation episodes), bad positioning
of the sounding lead (placed very high or very below of glottis, with a balloon located
in the ring cricoids) poor humidification of inspired air and the infection local[8]
[9].
Finally, between the related factors of risk with the doctor, are the lack of experience
and the difficulty of rank of the endotracheal pipe in the appropriated place[9].
Currently with more necessary diagnostic techniques we can confirm the illness with
more security. In these cases, the examination videolaryngostroboscopy and the electromyography
of the vocal muscle are decisive in the clarification of diagnstic[12]
[13].
This revision of literature was motivated by the comment in the practical clinic of
a great number of laryngeal aftermaths in patients submitted to the orotracheal intubation.
Of that is ahead important the knowledge, for the professionals of the area of health,
the types of complications and its causes, with intention to prevent them, adopting
measured of prevention of these injuries.
Discussion
Symptoms
The laryngeal symptoms are disturbances of the speech or complaints related to the
aerial ways. The disturbances of the speech can be told or be perceived by the professional
listener as dysphonia or hoarseness, whisper, complete aphony, vocal fatigue and incapacity
to support the speech and the volume adequately. Other symptoms can include pain of
throat, fullness and sensation of strange body in the throat. The majority of these
phonatory symptoms is supported by an increase in the disturbance parameters that
reflect in variations in the intensity and frequency in the vibration of the vocal
folds[14]
[15]
[16].
The pharyngolaryngotracheal symptoms as pains of throat, difficulty to speak, cough,
increase of secretions, pain to swallow, are also common in the one post-surgical[1].
In relation to the phonatory symptoms, it is important to notice that they auto are
limited and disappear inside of 24 the 48 hours. When become persistent for more than
72 hours, the anesthesiologist must suspect of injury of the vocal folds. When the
phonatory symptoms are followed of infirmity of aerial ways, as stridor, dyspneia
or aspiration, the injury in the cricoaritenoid joint is suggestive and is important
that if it makes an evaluation of the aerial superior ways[17].
Factors Associated
Great part of the larynx injuries after-intubation if decides spontaneously, for the
capacity of regeneration of the epithelium. However, in determined circumstances that
take to the aggravation of the tissue perfusion and deficient healing, the evolution
of this process can aggravate and originate laryngeal injuries of changeable gravity,
as it occurs in weak patients, diabetic, with hemodynamic alterations or systemic
infections[1].
Some factors are suggested for the formation of granulomas: the adult, feminine sort,
anemia age, hypotension, malnutrition, respiratory infection, diabetes mellitus and
other fellow creatures to the predisposing and/or triggering factors in general way[18]
[19].
It was observed that the risk and the incidence of paralysis of the vocal folds had
increased with the age and was three times bigger in patients with age between 50-69
years. The risk also duplicated in patients who had as comorbidity, diabetes mellitus
and arterial hypertension[20].
The fact of diabetes mellitus to be associated with peripheral neuropathy can increase
the susceptibility to the paralysis of the vocal folds[21]. On the other hand, the arterial hypertension is associated the atherosclerotic
alterations arterial of the larynx. Associated to this, the insufficiency of the microcirculation
in the recurrent laryngeal nerve also can be caused by compression mechanics for the
ballonet of the tracheal pipe. Therefore, the recurrent nerve and its peripheral ramifications,
muscles and fabrics of the larynx can be more vulnerable the mechanical damages and
to the pressure of the cuff of the tracheal pipe in patients with diabetes mellitus
and hypertension of what in others patients[20].
Relation with the time
In a generalized manner, drawn out time is considered the superior periods the 24
or 48 hours of orotracheal intubation, varying between some studies[22]
[23]
[24].
The constant movements of the neck, carried through for the patient in agitation state,
provoke friction of the sounding lead and its ballonet throughout the respiratory
treatment. In the patient without sedation reflected movements of deglutition and
fouling of the vocal folds are gifts also on the tracheal pipe. Thus, how much bigger
the time of the intubation greater is the risk of occurrence of these injuries[2].
Were verified 2% of stenosis of the larynx in patients with orotracheal intubation
between three and five days and 5% of stenosis of the larynx with orotracheal intubation
between six and ten days. This study it showed that the gravity of the larynx illness
directly was related to the duration of the orotracheal intubation[25]. In 73 patients, in which was carried the tracheotomy in 6th day of orotracheal
intubation, one evidenced that the lesser time of exposition of the larynx to the
trauma of the orotracheal cannula seems to cause few complications[26].
The risk and the incidence of paralysis of the vocal folds had increased with the
duration of the intubation. The risk was folded for duration of the orotracheal intubation
between 3-6 hours and was seven times bigger for duration between 6-9 hours[20]. The relation between the drawn out intubation and an increase of the risk of immobility
of the vocal folds was clear in before studies[11]
[27].
In the case of granulomas, even so they occur, more commonly, in intubations drawn
out, also had been diagnosised in intubated patients for short period of time. This
leads to believe that the intubation time does not seem to be the only determinative
factor for the appearance of lesion[7]. The fact of that some patients develop granulomas exactly after few hours of intubation,
also was detached by others authors[28]
[29].
Relation with the tube size
The inadequate diameter of the intubation sounding leads and the difficulty in keeping
immobilized the intubated patient are predisposing factors to the development of injuries
of aerial ways. Thus, the choice of the diameter of the cannula is an aspect important
to be considered, a time that, for the configuration of glottis in V, the posterior
portion of the larynx keeps soul contact with it. To if using tracheal cannula more
calibrous, this region suffers the consequences from the ischemia caused for its compression
on the mucous. In these conditions, one soon observes necrosis and superficial ulceration
of the mucosa after extubation[1]
[2].
Relation with the pressure
When if they use tracheal cannula with ballonet, sends regards that the pressure in
its interior if keeps inferior to the one of the pressure of hair perfusion, that
is, minor who 30 cmH2O[30]
[31].
Experimental study in intubated rats was become fulfilled, varying the pressure in
the ballonet of 20 the 100 mmHg. This was evidenced that the sprouting of injuries
directly was related to the rise of the pressure in the interior of the ballonet,
especially when exceeds the pressure of hair perfusion (25 mmHg), generating, sequentially,
ischemia on the mucous, damage to the sanguineous supplement for the perichondrium,
local ulceration, secondary settling of bacteria and chondritis[30].
On the other hand, after histological analysis of the tracheal mucous of dogs in the
place of contact with the ballonet, observed when comparative epithelial injuries
to the normal respiratory epithelial, as areas of superficial erosion and eyelash
falls, exactly with the use of only 13 pressures of cmH2O[31]. It is standed out that great part of these injuries if decides spontaneously, for
the capacity of regeneration of epithelial[32].
The measure of the pressure of the ballonet is not carried through routinely in the
surgical center or the units of therapy intensiva[2]. The great importance of the monitoring of the pressure in the interior of the ballonet
comes being evidenced for some authors, for being simple maneuver, of low cost, carried
through with digital manometer portable[31]
[33].
Edema
The space of Reinke, the superficial layer of the proper blade of the vocal fold,
is crucial for the vibration of the vocal folds. The endolaring breaking, of this
structural layer, for the aggressive intubation, can result in edema of the vocal
folds, hindering, due to rigidity of the vocal fold, the perfect wavelike movement
it mucous, consequently leading to an alteration in the phonatory quality. For low
the lymphatic draining, the resorption of edema that it occupies this space of Reinke
can be slow, what it would make it difficult the vocal recovery, being able to become
the persistent dysphonia[1]
[17].
Ulcer
The classic “ulcer of contact” was originally described for Chevalier Jackson, whom
it affirms to be caused by the high pressures exerted for the pipe against the posterior
part of the larynx and due to mechanic abrasion[34].
In a sample of 82 patients, one met 77 patients (94%) with some laryngeal damage in
the initial laryngoscopy. Of these 76 (98.7%) had presented ulceration in the mucous
in the posterior portion of both true the vocal folds. Exactly the area where the
tracheal pipe makes direct contact with larynx[4].
It was verified that the ulcer proceeds to the appearance of laryngeal granuloma[26].
Laceration
The laceration of vocal fold, constituted of a direct glottis injury, is cause of
vocal consequences and occurs frequent when a intubation in emergency conditions is
effected, it are of the structures of reanimation or surgical block. Moreover, some
factors of risk can be related to the occurrence of laceration in the vocal fold:
inexpertly of the professional, difficulty in displaying the anatomy of the patient,
use of sounding leads of bore more raised in a patient with inadequate relaxation
of its glottis[8].
The healing of the lacerations of mucosa of the larynx can occur to the cost of tacks
and fibroses. When if they install in the previous commissure of glottis promote great
damage of the voice, for compromising the phonatory portion. Already the cicatricial
processes that involve the posterior portion of glottis can determine nip of the glottic
light, generating symptoms as dyspnea and weak and weak voice. It has situations where
the arytenoids muscles are injured and fibrosis that form in this place hinders the
complete abduction them vocal folds, which if keep in the medium region, simulating
paralysis larynx picture[1].
The lacerations that reach the layers deepest of the proper blade and the vocal ligament
mainly harm the wavelike movement of mucous, modifying the vocal quality and hindering
the modulation of voice[1].
Cartilaginous Trauma
The arytenoids cartilages are more vulnerable to the traumas of intubation for being
located in the posterior region of glottis. The aggressive orotracheal intubation
with a pipe of inadequate diameter or when the endotracheal pipe is inserted, while
the vocal folds are still in the medium position, can damage both the vocal folds
and the cricoaritenoid joints. In the same way, the removal of the endotracheal, concomitant
pipe the cough can dislodge arytenoids and still result in one glottis incompetente[15]
[35]. These sub-dislocations cause asymmetries of the vocal folds and its movements.
Some patients with larynx asymmetries develop secondary injuries, as the vocal nodules,
had to the constant muscular compensations during the speech[1].
Dysphonia
One of the symptoms most frequent presented by the patients in the postoperative period
is the hoarseness, that can be present in 14,4% to 50% of the patients submitted to
the orotracheal intubation. Its frequency if must to the raised incidence of laryngeal
injuries during the orotracheal intubation, mainly when carried through without the
choke neuromuscular[36]
[37]. This symptom, in the great majority of the times, is temporary, lasting on average
the two three days. However, in 10% of the cases the hoarseness becomes permanent,
modifying the quality of life of the patient who had normal voice before the surgery[1].
The majority of the injuries are caused by the direct injury on the vocal folds, causing
edema or ulcerations or for alteration of the mobility of the cricoaritenoid joint
and for the effect of mold caused for the translarynx cannula. Such effect disappears,
most of the time, with the regression of the inflammatory process[35].
Dysphonia and after-decannulation bronchoaspiration result, habitually, of the limitation
of the fouling of the vocal folds. When recovery of the mobility of the cricoaritenoid
joint exists and the effect of mold for the cannula subsides, have the return of the
voice and the control of the bronchoaspiration to normal[26].
Dysphagia
The drawn out orotracheal intubation can provide to injuries in the verbal socket,
pharynx and larynx, that cause reduction of the motor patterns and local sensitivity
and compromise the process of the deglutition, determining the oropharyngeal dysphagia.
These can unchain problems as the malnutrition and the aspiratory pneumonia, getting
worse significantly the clinical state of the hospitalized patient[38].
It was demonstrated that patient submitted to the orotracheal intubation they present
alterations in pharynx the verbal phase and of the deglutition, frequently followed
of larynx penetration and aspiration, being common the presence of more than an alteration
for each evaluated adult, determining lack of functionality in the process of the
deglutition. Moreover, the functions related to these structures, as the breath, says
and the deglutition to it, is not carried through during the institution of the orotracheal
intubation, propitiating reduction of the larynx function and consequent inactivity
of the musculature in the period of its utilization[4].
Paresis and paralysis of vocal preach
The incidence of paralysis of vocal fold varies of 1%[39] the 37%[27]. This discrepancy exists because some classify as paralysis the paresis orotracheal
after-intubation[7].
Paresis of the vocal folds is the reduction in varied degree of the mobility of the
vocal folds, separately or not, caused for the direct trauma of the endotracheal cannula,
mucous or muscular alterations or alteration of the mobility of the cricoaritenoid
joint. The paresis after-intubation is, most of the time, transitory, returning the
vocal folds to normal after the regression from the inflammatory alterations[40].
When the consequent injury to the orotracheal intubation if extends to the intrinsic
muscles of the larynx, can unchain paresis or paralyses of the vocal, temporary or
definitive folds. The paralysis or setting of the vocal folds is frequently unilateral,
but it can be bilateral. Respiratory insufficiency can be presented after as stridor
and up to six hours the decannulation. The unilateral paralyses harm the vocal emission
sufficiently; therefore the paralyzed vocal fold is located more laterally than the
healthy one hindering the perfect contact between them during the speech. In these
conditions, the voice becomes weak and weak, resulting in fatigue and exhausting muscular
effort during the speech. In the bilateral paralyses the respiratory symptoms of dyspneia
predominate a time that both the vocal folds are hindered of if abducting. In these
cases, the voice is little commited[1]
[26].
Moreover, the induced larynx dysfunction for the orotracheal intubation can premake
use the patients to the aspiration after-extubaton[14], factor of risk for pneumonia, what it would increase the postoperative morbidity
and mortality.
It is probable that the paralysis of the vocal folds after the intubation has origin
in damages to the nerves caused for the compression of the microcirculation, affecting
the nerves of the larynx. It has some possible mechanisms for this: the tracheal pipe
can cause acute inflammation in the larynx, that is, erythema, ulceration and granulomas,
and these pathological changes can induce to the vocal paralysis; the pressure of
the ballonet of the endotracheal pipe could potentially compress the recurrent nerve
and its peripheral branches in the larynx, causing degeneration and sub-paralysis
of the nerve. This insufficient microcirculation for the supplying of the recurrent
nerve and its peripheral ramifications, due to compression mechanics of the ballonet,
can cause ischemia and neuronal degeneration e, subsequently, paralysis and immobility
of the vocal folds[20].
The translarynx pipe can also cause sensorial denervation of the larynx for the constant
pressure[14], compromising the normal protection of the laryngeal mechanisms and eliminating
the reflected arc that mediates the phase of the laryngeal abduction the muscular
function of pharynx[42].
It was observed that the left vocal fold showed to be two more vulnerable times to
the paralysis of what the right vocal fold. This can occur due to insertion of the
pipe, the right for left, and to the setting of the tracheal pipe in the right angle
of the mouth, what it would more injure it with frequency[20].
Studies using the eletromyogram (EMG) to test laryngeal the nerve inferior, in the
occurrence of immobility of the larynx after-intubation, did not disclose parcel neurogenic
(no alteration of the conduction of the nerve or potentials of denervation)[43]. For the fact of that the innevartion of the larynx is complex, the presence of
a normal EMG necessarily does not mean to conclude that it has absence of abnormalities
of nerve[8]. The paralysis is accepted for the majority of the authors as of origin purely mecanic[43].
Polyp
After the extubation, the frustrate and overwhelming attempts of the patient in emitting
the voice of “more clean” form, unchains muscular efforts adds and tension of the
cervical musculature and the larynx. This inadequate standard of speech can become
habitual and the traumatic and constant impact of the vocal folds during speaks will
give to origin the secondary injuries on the mucous covering of the larynx, as the
vocals polyps.
Granulomas
Granulomas are rounded off injuries, of diverse unilateral or bilateral colorations
(rosy, whitish or wine), most of the time pediculated, presenting itself with smooth
or irregular surface. Its pedicles of implantation if insert in the posterior of glottis,
especially to the level of the vocal apophysis, local region where the cannula keeps
soul contact with the mucosa of larynx[7].
It was observed enters the main etiologies, the vocal abuse (33.3%), gastroesophageal
reflux (30.3%), the orotracheal intubation (22.7%) and idiopathic origin (9%)[44].
Granulomas are, in general, a unspecific inflammatory process formed by fabric of
granulation[45]. The healing of the larynx that if carries through for second intention complex
and is influenced by constant movement of nip and expansion of this, occurred during
the breath, speech and deglutition. The repairing of the ulcers of the epithelium
is initiated in the basal membrane when she is unbroken. However, if this was destroyed,
the healing process is slow, initiating from the edges of the fabric ulcerated[46].
The vocal symptoms after appear the 15 to 20 days of the removal of the tracheal pipe,
however when small they cannot cause symptoms. When experience symptoms implant in
the previous phonatory glottic portion cause damage to the vocal emission[1]. Os add include sensation of strange body, cough, cough and pain in the topography
of larynx[7].
The occurrence of granulomas has fort predominance in the masculine sort, except in
the cases of after-intubation. In a sampling group of 66 laryngeal patients with granulomas,
of which 15 if had developed intubation after, of these, six belonged to masculine
sort and nine to female sort[44]. To explain this fact, we can evoke the larynx configuration of the woman, who presents
minors consequently dimensions and, allows to a bigger contact of the cannula with
the mucosa of the aereal ways[12]
[47]. Moreover, the fragile perichondrium that recovers the vocal apophysis of the arytenoids
cartilages and the poor vascularization of the local mucous is factors adds that they
become the region most vulnerable the traumas of intubation[7].
Granulomas of larynx endotracheal after-intubation is one of the complications most
common, varying between 26,7%[26] and 44%[11]. Its appearance occurs in about 21 days, while it approximately has spontaneous
regression in a period of three months, in the majority of cases[6]
[11]
[26].
The diagnosis is made through anamneses, otolaryngologic examination, videolaryngoscopy,
videolaryngostroboscopy or even though for the indirect laryngoscopy[48].
As in the cases after-intubation the causal factor of granulomas it is not perpetuated,
generally its spontaneous regression is observed, or by means of aggressive phototherapy
or still resolution after surgical removal, in general carried through in most voluminous
or the bilateral cases[44].
The botulinum toxin injection in the larynx is a great advance in the treatment of
granulomas, being a safe and efficient procedure and that it can be used in the cases
that do not answer to the clinic treatment.
Stenosis larynx
Important cause of hoarseness after the extubation, larynx stenosis is one of most
frightful. All the boarded factors can contribute for its sprouting. Beyond the serious
vocal commitment, the patient presents intense dyspneia. In centers exactly considered
of excellence in intensive cares, the occurrence of stenosis of larynx for orotracheal
intubation varies of 0,5%[4] the 14%[50].
In the practical clinic, the majority of the patients who presents with stenosis tracheal
after-intubation possess mature fibrotic scars, with minimum evidence of inflammation
of the aerial ways. These patients had been typically submitted to the intubation
in a relatively distant past, and some of them could have been treat for asthma before
the correct diagnosis. The precocious phase of stenosis tracheal after-intubation
is characterized by ulceration of the mucosa and perichondritis, followed for exophytic
granulation fabric formation. Later, the granulation fabric gradually is substituted
by a mature fibrotic scar, that if contracts and originates the classic injury of
estenosis[40]
[51]
[52].
With the intubation the use of techniques of closed ventilation is common, being the
cannula in narrow contact with the subglottic wall. This region is narrowest of the
superior aerial ways, becoming, therefore, most susceptible to injure the contact
to it with rigid cannula. This contact takes edema of mucosa and hyperemia, stasis
of secretion and local infection, being able to develop itself, later, weaved of granulation
and necrosis. When of the withdrawal of the cannula, intubation after drawn out, the
wall of the subglottic region already is in healing phase, with collagen formation
that, after the maturation, is contracted circumferentially, being able to provoke
partial or complete stenosis[50]
[53].
When these alterations evolve for subglottic stenosis, almost always, in children,
become fulfilled it tracheotomy. This propitiates to the medical time for the evaluation
and for the definitive behavior but, during this interval of time, it becomes the
daily routine of the difficult tracheotomizated patient and traumatic[54]. Beyond it, stenosis demands cares that can involve multiple endoscopy, endoscopic
dilatations, endoscopic resections, cryosirurgical, laser resections, tracheoplasty,
graft of cartilage and cricotracheal resections, with the treatment if extending for
months or years, needing, to the times, even of definitive tracheotomy[55]
[56]
[57]
[58]
[59].
