Computed tomographic assessment of airflow obstruction in smoke inhalation injury: Relationship with the development of pneumonia and injury severity

Acute Respiratory Distress Syndrome, Mechanical Ventilation, and Inhalation Injury in Burn Patients

Respiratory failure occurs with some frequency in seriously burned patients, driven by a combination of inflammatory and infection factors. Inhalation injury contributes to respiratory failure in some burn patients via direct mucosal injury and indirect inflammation. In burn patients, respiratory failure leading to acute respiratory distress syndrome, with or without inhalation injury, is effectively managed using principles evolved for non-burn critically ill patients.

First-day computed tomography: does it has a role in the assessment of patients with inhalation lung injury?

Background

Inhalation lung injury occurs in almost one-third of all serious burns and is responsible for a considerable proportion of burn patient fatalities each year. History of closed space fire or unconsciousness at the accident site, occurrence of pharyngeal or facial burns, hoarseness, and wheezing, and laboratory tests that include blood gas abnormalities or Carboxyhemoglobin levels in blood ˃ 10% are used to diagnose inhalation lung injury. It is also characterized by radiological findings of alveolar or interstitial edema, atelectasis, and/or consolidations, as well as the presence of erythema with laryngeal or tracheal edema in the bronchoscope.

Objectives

To study the diagnostic and prognostic efficacy of radiologist score and bronchial wall thickening as radiological CT findings in inhalation lung injury.

Methods

This prospective case–control study included 48 patients with inhalation lung injury (ILI) as a case group and 10 patients without ILI were selected as the control group, all recruited from the burn and plastic department. Within the first 12 h of suspected ILI, a fiberoptic bronchoscope was done to confirm the diagnosis. An initial chest X-ray was done followed by computed tomography through which the radiologist score (RADS) together with bronchial wall thickening (BWT) was done.

Results

Duration of ventilation was higher in cases than in controls (8.50 ± 3.94 vs 3.25 ± 0.50). The hospital duration was higher in cases than in controls (13.6 ± 4.68 vs9.50 ± 4.52). The BWT was 2.12 ± 0.66 (mean ± SD) in the ILI group while the control group was 1.32 ± 0.48 (mean ± SD). Correlating between baseline PaO2 and RADS score and BWT, it was found that there was a highly significant negative correlation between PaO2 and RADS score and BWT among inhalation lung injury patients (P value 0.001). The sensitivity of BWT in the detection of the need for mechanical ventilation was 83% at a cut-off point of 1.65. Its specificity was 78% and accuracy 75%.

Conclusion

CT done within 24 h of burn patients has a good role in the diagnosis and management of ILI from the burn.

Sensing Inhalation Injury-Associated Changes in Airway Wall Compliance by Anatomic Optical Coherence Elastography

Quantitative methods for assessing the severity of inhalation (burn) injury are needed to aid in treatment decisions. We hypothesize that it is possible to assess the severity of injuries on the basis of differences in the compliance of the airway wall. Here, we demonstrate the use of a custom-built, endoscopic, anatomic optical coherence elastography (aOCE) system to measure airway wall compliance. The method was first validated using airway phantoms, then performed on ex vivo porcine tracheas under varying degrees of inhalation (steam) injury. A negative correlation between aOCE-derived compliance and severity of steam injuries is found, and spatially-resolved compliance maps reveal regional heterogeneity in airway properties.

Serious Inhalation Injuries From Military Operations in Afghanistan, Iraq, and Syria

OBJECTIVE

To characterize serious inhalation injuries seen during recent military operations, and assess whether bronchoscopic severity findings were associated with clinical presentation and outcomes.

METHODS

Service members who suffered inhalation injuries while deployed to Iraq, Afghanistan, or Syria from 2001-2018 were identified using ICD-9 and 10 codes from the Expeditionary Medical Encounter Database (EMED), which is abstracted from patient records in forward-deployed medical facilities. Further information including demographics, mechanism of injury, mortality, total burn surface area (TBSA), degree of facial burn, total Injury Severity Score (ISS), and first post-injury bronchoscopy notes were collected. Patients were excluded with ISS less than 16 or without sufficient details regarding bronchoscopy. Injuries were grouped based on bronchoscopic Abbreviated Injury Scores (AIS) into low-grade (AIS of 1), moderate-grade (AIS of 2), or high-grade (AIS of 3 or 4).

RESULTS

91 patients met inclusion criteria, with no significant differences in age, gender, paygrade, or service branch between degrees of injury. There were no statistical correlations between grade of injury and battle versus non-battle injury, blast versus non-blast mechanism, TBSA, or degree of facial burn. High-grade injuries had significantly higher ISS than low or moderate-grade injuries. After adjusting for ISS, the odds ratio of death was 10.4 (95% CI 1.47 to 74.53) for those with high-grade and 3.7 (95% CI 0.45 to 32.30) for those with moderate-grade compared to low-grade injuries.

CONCLUSION

In this cohort of deployed military members with inhalation injuries, initial bronchoscopic severity findings are strongly associated with mortality even after adjusting for ISS. The AIS may be an important prognostic tool in all of those with serious inhalation injuries.

Point-of-care endoscopic optical coherence tomography detects changes in mucosal thickness in ARDS due to smoke inhalation and burns

BACKGROUND

The prevalence of acute respiratory distress syndrome (ARDS) in mechanically ventilated burn patients is 33%, with mortality varying from 11-46% depending on ARDS severity. Despite the new Berlin definition for ARDS, prompt bedside diagnosis is lacking. We developed and tested a bedside technique of fiberoptic-bronchoscopy-based optical coherence tomography (OCT) measurement of airway mucosal thickness (MT) for diagnosis of ARDS following smoke inhalation injury (SII) and burns.

METHODS

16 female Yorkshire pigs received SII and 40% thermal burns. OCT MT and PaO₂-to-FiO₂ ratio (PFR) measurements were taken at baseline, after injury, and at 24, 48, and 72h after injury.

RESULTS

Injury led to thickening of MT which was sustained in animals that developed ARDS. Significant correlations were found between MT, PFR, peak inspiratory pressure (PIP), and total infused fluid volume.

CONCLUSIONS

OCT is a useful tool to quantify MT changes in the airway following SII and burns. OCT may be effective as a diagnostic tool in the early stages of SII-induced ARDS and should be tested in humans.

Safety of Nebulized Epinephrine in Smoke Inhalation Injury

This pilot study was conducted to profile safety of nebulized racemic epinephrine when used as a therapy for smoke inhalation injury in severely burned children. We enrolled 16 patients who were 7 to 19 years of age ([mean ± SD], 12 ± 4 years) with burns covering more than 30% of the TBSA (55 ± 17%) and smoke inhalation injury, as diagnosed by bronchoscopy at burn center admission. Patients were randomized to receive either standard of care (n = 8), which consisted of nebulized acetylcysteine, nebulized heparin, and nebulized albuterol, or to receive standard of care plus nebulized epinephrine (n = 8). Primary endpoints were death, chest pain, and adverse changes in cardiopulmonary hemodynamics (arrhythmia, arterial blood pressure, electrocardiographic [ST segment] changes, and peak inspiratory pressure). Additional endpoints included total days on ventilator, pulmonary function, and physiological cardiopulmonary measurements at intensive care unit discharge. No adverse events were observed during or after the nebulization of epinephrine, and no deaths were reported that were attributable to the administration of nebulized epinephrine. The groups did not significantly differ with regard to age, sex, burn size, days on ventilator, pulmonary function, or cardiopulmonary fitness. Results of this pilot trial indicate epinephrine to be safe when administered to pediatric burn patients with smoke inhalation injury. Current data warrant future efficacy studies with a greater number of patients.

Nebulized heparin and N-acetylcysteine for smoke inhalational injury: A case report

RATIONALE

Every year, ∼40,000 people suffer burn-related injuries in the United States. Despite recent advances, the odds of dying from exposure to fire, flames, or smoke are one in ∼1500. Smoke inhalation causes injury to the airways via a complex physiological process, and the treatment is mainly supportive. Many recent interventions aim to decrease the formation of fibrin casts, the main cause of airway damage in these patients. Among these, treatment with a combination of nebulized heparin and N-acetylcysteine (NAC) has shown benefit.

PATIENT CONCERNS

We describe the case of a 58-year-old man who presented after smoke inhalation during a fire. Soot was found in the nostrils when he was admitted to our hospital, and after he began coughing up carbonaceous material, he was electively intubated and placed on volume assist control ventilation.

DIAGNOSIS

Bronchoscopy on the first day of intensive care confirmed the injury from smoke inhalation and revealed mucosal edema and soot involving the tracheobronchial tree.

INTERVENTIONS AND OUTCOMES

Inhaled unfractionated heparin of 10,000 IU in 3 mL of 0.9% normal saline alternating every 2 hours with 3 mL of 20% NAC was started 48 hours after admission and continued for 7 days. Bronchoscopy on the fifth day of intensive care showed significant improvement in airway edema and a resolution of soot.

LESSONS

On the basis of our experience with this case and limited literature, we posit that nebulized heparin and NAC may be of benefit in patients with inhalational smoke-induced lung injury and mild-to-severe lung injury scores.