ORIGINAL ARTICLE Efficacy of Fiberoptic Laryngoscopy in the Diagnosis of Inhalation Injuries Thomas Muehlberger, MD; Dario Kunar, MD; Andrew Munster, MD; Marion Couch, MD, PhD Background: Asignificantproportionofburnpatientswith Results: Six (55%) of 11 patients had clinical findings and inhalation injuries incur difficulties with airway protection, symptoms that indicated, under traditional criteria, endo- dysphagia, and aspiration. In assessing the need for intu- tracheal intubation for airway protection. Visualization of bation in burn patients, the efficacy of fiberoptic laryngos- the upper airway with fiberoptic laryngoscopy obviated the copy was compared with clinical findings and the findings need for endotracheal intubation in all 11 patients. These of diagnostic tests, such as arterial blood gas analysis, mea- patients also failed to evidence an increased risk of aspira- surement of carboxyhemoglobin levels, pulmonary func- tion or other swallowing dysfunction. tion tests, and radiography of the lateral aspect of the neck. Conclusions: In comparison with other diagnostic cri- Objective: To determine if these patients were at risk teria, fiberoptic laryngoscopy allows differentiation of for aspiration or dysphagia, barium-enhanced fluoro- those patients with inhalation injuries who, while at scopic swallowing studies were performed. risk for upper airway obstruction, do not require intu- bation. These patients may be safely observed in a moni- Design: Prospective study. tored setting with serial fiberoptic examinations, thus avoiding the possible complications associated with in- Settings: Burn intensive care unit in an academic ter- tubation of an airway with a compromised mucosalized tiary referral center. surface. In these patients, swallowing abnormalities do not manifest. Main Outcome Measures: Need for endotracheal in- tubation and potential for aspiration. Arch Otolaryngol Head Neck Surg. 1998;124:1003-1007 NHALATION INJURY is defined as in- knowledge, there has never been a prospec- jury to the epithelial lining of the tive analysis of the potential for patients with lower tracheobronchial tree and edema and a decreased range of motion of the lower airway. It is present in facial and cervical muscles to aspirate or to approximately one third of pa- develop dysphagia after sustaining a less se- Itients treated in burn centers.1 Since the vere inhalation injury. most immediate danger to patients with in- halation injuries is upper airway obstruc- RESULTS tion due to edema, early and even prophy- lactic endotracheal intubation based on Six (55%) of 11 patients had clinical find- clinical assessment is the standard conser- ings and symptoms that suggested, with- vative approach to treating these patients.2 out fiberoptic laryngoscopy, that they Signs of respiratory failure, unconscious- should be intubated for airway protec- ness, or the presence of major burns often tion. In total, 8 patients (73%) presented make the diagnosis of severe inhalation in- with at least 4 signs and symptoms indi- jury obvious. Yet, patients without burns, cating a possible upper airway compro- stridor, hypoxemia, or major thermal inju- mise. The history taken from the 11 pa- ries suspected of having an inhalation in- tients revealed that 73% (8/11) were jury constitute a less defined subpopula- exposed to fire and smoke within an en- tion. Currently, diagnostic precision is closed space such as a house or car. Clini- From the Departments of difficult in identifying less severe injuries cal assessment showed the incidence of Surgery (Drs Muehlberger that do not require intubation. Unneces- and Munster) and Otolaryngology–Head and sary intubation places these patients at risk Neck Surgery (Drs Kunar and for damage to the larynx and subglottic re- gions; therefore, the patients with less se- This article is also available on our Couch), The Johns Hopkins Web site: www.ama-assn.org/oto. University School of Medicine, vere inhalation injuries need to be identi- Baltimore, Md. fied to safely avoid intubation. Also, to our ARCH OTOLARYNGOL HEAD NECK SURG/ VOL 124, SEP 1998 1003 ©1998 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 10/02/2021 PATIENTS AND METHODS Browder charts. An examination was performed to detect hoarseness or dysphonia as subjective changes of voice qual- ity. Other recorded clinical parameters were the presence From October 1996 to July 1997, 62 consecutive patients with of cough, difficulties or pain with swallowing, singed fa- suspected inhalation injuries were admitted to the Baltimore cial or nasal hair, facial burns, loss of consciousness, car- Regional Burn Center in Maryland. Inclusion criteria were ex- bonaceous sputum, and oral and/or nasal soot. posure to fire and smoke within an enclosed space, singed fa- Blood samples were drawn to analyze arterial blood gases cial hair, singed nasal vibrissae, facial burns, dysphonia or and to determine carboxyhemoglobin (COHb) levels. All hoarseness, oral and/or nasal soot, cough, carbonaceous spu- patients underwent pulmonary function tests to obtain res- tum, and swallowing difficulties. Exclusion criteria for this piratory flow-volume loops. The flow-volume curves were study were the presence of stridor (8 patients), altered men- considered to be abnormal and consistent with variable tation either previously existing or due to administered nar- extrathoracic airway obstruction if both a flattened configu- cotics (19 patients), and burn injuries covering more than 15% ration of the inspiratory curve suggested diminished flow rates of body surface area (13 patients) that mandated immediate and a ratio of expiratory flow to inspiratory flow at 50% of protectionoftheairwaybyintubation.Noncomplianceorleav- the vital capacity (FEF50/FIF50) exceeding 1.0 was present. ing against medical advice (4 patients), facial palsy not per- Other parameters were the mean forced expiratory volume mitting pulmonary function tests (1 patient), or intubation in 1 second (FEV1), and forced vital capacity (FVC). Radio- prior to admission to the burn unit (6 patients) also excluded graphs of the lateral aspect of the neck were obtained and patients from the study. Eleven patients (8 males, 3 females; evaluated in view of possible soft tissue changes, especially mean ± SD age, 43 ± 16 years; age range, 12-88 years) partici- since edema of the epiglottis similar to epiglottitis might be pated in our study. Two patients were in their teens; 4 patients detected. Barium-enhanced video fluoroscopic swallowing were in their third decade of life; 1 patient was in her fourth studies were performed on patients with clinical symptoms decade of life; 3 patients were in their fifth decade of life; and consistent with possible dysphagia or aspiration on hospi- 1 patient was in the ninth decade of life. Of the 11 eligible pa- tal day 2 to document and quantitate dysphagia or aspira- tients, 2 had a history of mild asthma but denied the use of tion. Dysphagia was defined as the inability to accept and inhalers or other medication in the past. Eight patients were safely transport food and liquid from the mouth to the stom- smokers. Three patients had no skin burns; the total body sur- ach. All 11 patients underwent laryngoscopy with a flexible face area burned in the remaining 8 patients ranged from 4% fiberoptic laryngoscope (Olympus American Inc, Melville, to 12%. No patient had sustained full-thickness facial burns. NY). Local anesthesia in the nares consisted of the admin- On admission to the burn unit, each patient gave a his- istration of 2% lidocaine spray or jelly. The attending phy- tory, with reference to the mechanism of injury, site of ac- sician, burn unit fellow, or otolaryngology senior resident cident, loss of consciousness, and duration of smoke ex- performed all the fiberoptic examinations. The laryngeal ex- posure. The location and percentage of total body surface amination results were recorded on videotape and were used area of all burns were recorded on standard Lund and for comparison if serial examinations were needed. physical signs and symptoms to be highest for singed Radiographs of the lateral aspect of the neck did not facial hair (91% [10/11]), dysphonia (82% [9/11]), and show soft tissue abnormalities in any of the patients. They facial burns (73% [8/11]). Hoarseness was found in 55% were reviewed independently by a radiologist and mem- (6/11) of the patients. Cough (55% [6/11]) and soot in the bers of the burn unit. oral or nasal areas (45% [5/11])were also frequently seen Findings of the fiberoptic laryngoscopy led to the di- (Figure 1). vision of patients into 2 groups. The first group consisted Arterial blood gas analysis showed 2 patients to be of 7 patients with minimal supraglottic mucosal edema, mild hypoxemic on admission with a PaO2 of 57 mm Hg and pooling of secretions, fully mobile true vocal folds, and vis- 59 mm Hg, respectively. These 2 patients had not re- ible ventricular folds. Inflammatory changes in these pa- ceived supplemental oxygen while being transported to tientswerenotsufficientlyseveretodistortsupraglotticstruc- the hospital. All other patients had significantly el- tures or to compromise the airway lumen. Some of these evated levels of arterial partial oxygen pressures (183 ± patients were found to have soot present in the nares 67 [mean ± SD] mm Hg). Carboxyhemoglobin levels were (Figure 2), oropharynx, nasopharynx, and even on the elevated in 4 patients (mean, 9.8%; range, 7.2%-14.9%). true vocal