Inhalation Burns

The Scar Solution Natural Scar Removal

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Burns of the larynx, trachea, and bronchi may be caused by inhalation of hot gases, steam, particulate matter in smoke, or of chemical substances released in industrial explosions or combustion. We have encountered burns due to house fires, motor vehicle accidents, electrical exposure, gas explosion, airplane crash, TV set explosion, and chemical inhalation (ammonia and hydrochloric acid), among many other origins of burns.16 It is often difficult to know precisely what the mixture of damaging agents was. In addition to heat, injury may be produced by irritant gases such as aldehydes, ammonia, and hydrochloric acid, and by particulate matter. Moylan and Chan observed by bronchoscopy that one-third of burn patients had evidence of inhalation injury.17 Ninety-seven percent of these had facial burns and 75% were injured in a

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figure 9-10 Findings in a patient who developed progressively severe dyspnea late after anterior chest trauma. A, Bronchoscopic examination shows tight, well-healed stenosis in midtrachea. B, Gross appearance of the site of left-sided transverse laceration of mediastinal trachea (arrow). The wedge defect brings to mind a woodsman's attack on a tree trunk. C, Resected specimen of stenosis. The stenotic airway is about one-fourth or less of the normal tracheal cross section. Also, see Figures 21 and 22 (Color Plate 14).

figure 9-10 Findings in a patient who developed progressively severe dyspnea late after anterior chest trauma. A, Bronchoscopic examination shows tight, well-healed stenosis in midtrachea. B, Gross appearance of the site of left-sided transverse laceration of mediastinal trachea (arrow). The wedge defect brings to mind a woodsman's attack on a tree trunk. C, Resected specimen of stenosis. The stenotic airway is about one-fourth or less of the normal tracheal cross section. Also, see Figures 21 and 22 (Color Plate 14).

figure 9-11 A 26-year-old patient suffered multiple trauma in a motor vehicle accident 5 months earlier, with initial bilateral pneumo-thoraces which responded to tube drainage. With late onset of dyspnea, a right main bronchial stenosis with nearly complete occlusion was identified. Two attempts were made at different institutions to dilate the stenosis. A, Inspiratory chest x-ray shows apparently good bilateral expansion. B, Expiratory film shows continued full expansion on the right due to air trapping. C, Bronchoscopy reveals nearly complete occlusion of the right main bronchus at the origin. Obstruction is not complete, however. Resection of the stenosis and reanastomosis of the right main bronchus allowed her to return to climbing in the Grand Tetons. Also, see Figure 23 (Color Plate 14).

figure 9-11 A 26-year-old patient suffered multiple trauma in a motor vehicle accident 5 months earlier, with initial bilateral pneumo-thoraces which responded to tube drainage. With late onset of dyspnea, a right main bronchial stenosis with nearly complete occlusion was identified. Two attempts were made at different institutions to dilate the stenosis. A, Inspiratory chest x-ray shows apparently good bilateral expansion. B, Expiratory film shows continued full expansion on the right due to air trapping. C, Bronchoscopy reveals nearly complete occlusion of the right main bronchus at the origin. Obstruction is not complete, however. Resection of the stenosis and reanastomosis of the right main bronchus allowed her to return to climbing in the Grand Tetons. Also, see Figure 23 (Color Plate 14).

closed space. Seventy-five percent of these patients developed severe respiratory complications and one-third of them died as a result of airway burns.

The patient often also suffers from cutaneous burns of varying extent and depth. When first examined, the patient may have significant burns of the oropharynx, largely of thermal origin. These commonly heal and regress so that the glottis may soon appear quite normal. Varying degrees of persisting injury are observed in the subglottic larynx and upper trachea, the worst being just beneath the glottis with gradual diminution of the effects of the burn proceeding distally.16 These burns appear to result more from chemicals and particulates in smoke, except in the case of steam burns. An exaggerated necrotizing process

figure 9-12 Example of complex tracheobronchial injury in an 8-year-old girl, thrown from a vehicle and crushed as it rolled over. A, Initial chest roentgenogram. Bilateral pneumothoraces (intubated) and extensive emphysematous dissection of chest wall muscles and planes. There is little evidence of rib fractures or displacement, due to flexibility of the rib cage in childhood. At the initial hospital, laparotomy was negative. Tracheal transection was identified and presumptive repair was done under cardiopulmonary bypass. B, Subsequent chest film shows complete opacification of the left chest. Eight days after injury, she was urgently transferred. The initial repair was found to be inadvertent anastomosis of trachea to right main bronchus rather than to trachea. The concurrent rupture of the left main bronchus went unrecognized. At right thoracotomy, the tracheobronchial repair and right hilum were mobilized intrapericardially. The left bronchial stump could not be freed under the aortic arch because of inflammation and early scar formation. This required mobilization via left thoracotomy. Left intrapericardial mobilization was also done and the aortic arch was freed. Finally, via sternotomy and transpericardial dissection between the vena cava and aorta, and after proximal tracheal mobilization, it was possible to implant the debrided left main bronchus in the left lateral wall of trachea above the prior anastomosis. A second anesthesia machine was used to reinflate the left lung prior to anastomosis, vastly improving oxygenation. If the pathologic findings after 8 days could have been anticipated, alternative incisions might have been possible. C, Tomogram showing final reconstruction. The upper arrow marks the glottic level. In the neocarina, the right main bronchus appears long due to deviation of the distal trachea to the right, below the left bronchial anastomosis (lower arrow). The patient's further course was excellent.

immediately below the cords was first noted in victims of The Cocoanut Grove fire and was attributed to eddy currents. Some unfortunate patients sustain injury extending into the main bronchi and below. The intensity of damage varies. Severe tracheobronchitis may be followed by mucosal sloughing. If the basal cell layer remains intact, early repair is accomplished rapidly, both clinically and experimentally. If the basal membrane is destroyed, granulations, cicatrization, and stenoses may follow.

A late complication of inhalation burn, 2 to 6 months after acute injury, is the formation of endobronchial polyposis.18,19 Significant hemoptysis occurs. Polyps regressed over 6 months without treatment in one patient and while receiving corticosteroids in another. Fatal bronchiolitis obliterans has been described as a late complication of inhalation burn following explosion in a confined space.20

Effects of inhalation injury and the intubation injury resulting during treatment are difficult to separate, especially since intubation is often performed early in the presence of respiratory symptoms. Burn injury may well make the trachea more susceptible to intubation injury. Stenoses are often of greater length than those resulting from intubation injury alone. Injury may also extend beyond the level of grossly visible changes. Often, the cartilages of the trachea appear to be only slightly injured. Peritracheal fibrosis is almost always found.

The incidence of stenosis due to burn injury is impossible to determine, given the variety and intensity of agents and the widespread use of intubation in management. Clinical reports are largely composed of patients who were intubated. Two of 38 survivors of burns treated with intubation developed subglottic stenosis in one series, and in another, 6 of 25 survivors of airway complications treated with tracheostomy developed tracheal stenosis. In a search for later sequelae of inhalation burns in 17 survivors, 4 had tracheal stenosis and 5 had significant tracheal granulomas. Gaissert and colleagues treated 18 patients with chronic airway compromise after inhalation burns; there were 18 tracheal stenoses, 14 subglottic strictures, and 2 main bronchial stenoses.16 Three patients developed laryngotracheal stenoses without intubation.

Evaluations of patients with inhalation burns include tracheal and laryngeal radiography followed by laryngoscopy and bronchoscopy under general anesthesia. In our 18 chronic patients, 14 had subglottic as well as tracheal stenoses, and in 4, the two areas were separated by a tracheal segment which was not stenosed.

If airway obstruction occurs, whether by laryngeal edema, inflammatory swelling, granulations, or later stenosis of the burned subglottic larynx and trachea, an airway is best established urgently by endotracheal intubation. Obstruction may also occur 3 weeks to 5 months after injury. If the patient has pulmonary damage that requires ventilation, a cuffed tube is necessary. Otherwise, it is preferable to avoid an inflated cuff.

For long-term management, tracheostomy becomes necessary if the patient's neck is not damaged by the burn. The tracheostomy usually lies within the damaged area of the trachea. As inflammation subsides, a T tube may be inserted to span the entire area of injury (see Chapter 39, "Tracheal T Tubes"). If the subglot-tic larynx is involved, as it often is, the T tube must extend up through the glottis. This is frequently necessary because the intensity of an inhalation burn is often greatest in the subglottic larynx. A T tube, with its upper end between the false and true vocal cords, usually permits hoarse or whispered speech as well as swallowing without aspiration. Training by a speech pathologist is advisable. If the proximal end of the T tube is sited in the subglottic location where there is burn injury, it will repeatedly become obstructed by granulation tissue.

The T tube maintains airway patency, preserves understandable phonation, and permits gradual resolution of burn injury to the mucosa and submucosa. Burn injury resolves only very slowly, and resulting cicatrization matures slowly, which is entirely parallel with the evolution of cutaneous burns. Attempts to perform surgical resection and early reconstruction of the airway are likely to fail.16 With patience and persistence by both the patient and surgeon, conservative management is most likely to result in a satisfactory airway, although not a normal one (Figure 9-13). Since cartilages remain basically intact, the goal is regression of granulations and stabilization of the mucosal and submucosal process. In 5 patients treated with T tubes only, and 4 with laryngofissure and T tube, decannulation was achieved between 4 to 61 months (mean 28 months) after injury. Four patients required permanent tracheal tubes (2 T tubes and 2 tracheostomy tubes).

Specific criteria for discontinuance of the T tube based on bronchoscopic observation or biopsy do not exist. Our management has been to attempt to remove the T tube when regression seemed adequate,

figure 9-13 Lateral cervical roentgenograms from an 18-year-old female suffering inhalation burn by toxic gases from combustion of plastic building materials. A, Diffuse upper tracheal stenosis (arrow). Posterior laryngeal calcification is visible superiorly. B, T tube in place, extending from the subglottic larynx into normal trachea. The sidearm of the T lies at the base of the neck. C, Result after 6 years of splinting is an apparently stable although narrowed subglottic larynx and proximal trachea. Dense reactive scar tissue appeared to have resolved to a degree. However, the patient went on slowly to laryngotracheal stenosis, which was successfully treated by laryngotracheal resection and reconstruction 13 years after decannulation (C). She has required several procedures for posterior commissural glottic stenosis and unilateral arytenoid fixation over subsequent years. The laryngotracheal repair has remained stable.

figure 9-13 Lateral cervical roentgenograms from an 18-year-old female suffering inhalation burn by toxic gases from combustion of plastic building materials. A, Diffuse upper tracheal stenosis (arrow). Posterior laryngeal calcification is visible superiorly. B, T tube in place, extending from the subglottic larynx into normal trachea. The sidearm of the T lies at the base of the neck. C, Result after 6 years of splinting is an apparently stable although narrowed subglottic larynx and proximal trachea. Dense reactive scar tissue appeared to have resolved to a degree. However, the patient went on slowly to laryngotracheal stenosis, which was successfully treated by laryngotracheal resection and reconstruction 13 years after decannulation (C). She has required several procedures for posterior commissural glottic stenosis and unilateral arytenoid fixation over subsequent years. The laryngotracheal repair has remained stable.

leaving a cannula or "button" in place to maintain the stoma during the test period. If resection of a limited residual stenosis is necessary, it is preferably done later than earlier, although good response has been reported to earlier repair on occasion.

Operative management is even more hazardous because so many burns involve the subglottic space, where airway reconstruction is more difficult, whether by single-stage laryngotracheal reconstruction or by laryngofissure with resurfacing and stenting. Four of 6 patients who ultimately underwent open repair of a subglottic stenosis had good results. Management of stenosis extending into the carina and main bronchi, fortunately rare, is even more difficult. We hesitate to use a T-Y tube since the bronchial ends of the tube may stimulate more reaction if they lie in areas of burn injury. Isolated bronchial stenosis has been managed by repeated dilation. An inlying stent would pose the danger of inciting granulomas.

Successful outcome of treatment does not result in a normal airway. The quality of voice is often diminished and a degree of hoarseness is present. Mild chronic wheezing and recurrent episodes of respiratory tract infections occur. We have seen a case of late recurrent obstruction, but there is no large experience with these injuries.

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