Combined carbon monoxide poisoning and smoke inhalational injury in a case of severe underlying lung disease

Acute inhalational injury secondary to burn exposure poses a high risk of morbidity and mortality among burn victims.1,2 Thermal injury, along with the inhalation of toxic gases such as carbon monoxide and cyanide, contributes to systemic toxicity and causes substantial damage to the airways and alveoli. Bronchoscopic evaluation often reveals airway erythema and edema, mucosal injury, and carbonaceous deposits.1 The management of smoke inhalational injury in patients with underlying lung disease is not well described. This perspective discusses inhalational injury and its impact on patients with underlying obstructive lung disease. We present a case of severe exacerbation of underlying obstructive lung disease in the setting of smoke inhalation. Similar cases are scarce in the literature, and guidelines on management have not been established. We reviewed the literature for similar cases, including proposed management strategies. Informed consent was obtained from the patient. Our patient was an elderly woman with underlying obstructive lung disease due to pulmonary sarcoidosis who was found unconscious during a house fire. She was intubated in the field for severe hypercarbic respiratory failure and altered mental status. She was transferred to the medical intensive care unit for further management. Inhalational injury is a comprehensive term that encompasses damage to the airway and alveoli caused by thermal or chemical injury or exposure to toxic fumes.3 Inhalational injuries carry a high mortality rate due to systemic toxicity and postexposure pulmonary complications.4 In 2016, smoke inhalation-induced lung injury was associated with in-hospital mortality of 26%.4 In those with burns with greater than 20% body surface involvement, mortality was 50%.4 Carbon monoxide poisoning is a feared toxicity from fires and smoke inhalation. Carbon monoxide poisoning is responsible for more than 50,000 emergency department visits, with mortality ranging from 1–3%.5 For patients with inhalational injury, especially in the setting of a house fire, prompt workup, including routine blood work, arterial blood gas analysis, carboxyhemoglobin measurement, cyanide level assessment, chest imaging, and bronchoscopy if clinically indicated, is usually recommended.1,3 Most burn centers have adopted standardized multidisciplinary approaches due to the high acuity and complexity of smoke inhalation cases.1,2,5,6 This comprehensive approach involves acute and aggressive airway management, treatment of concomitant systemic intoxication (carbon monoxide, cyanide), and regular airway inspections to facilitate clearance as needed.1,2,5,6 Interventions such as bronchodilators, mucolytics, and corticosteroids have been suggested to address airway inflammation and prevent further lung injury.1,2,5,6 Early and aggressive management is crucial to prevent rapid airway compromise with severe inflammation, progression to acute respiratory distress syndrome, and subsequent multiorgan dysfunction.2 Despite existing guidelines for inhalation injury, additional research is necessary to evaluate outcomes and management strategies for patients with underlying lung disease. The impact of smoke inhalation on patients with underlying obstructive lung disease remains unclear. A study performed in Turkey in 2012 in Ankara Numune Training and Research Hospital’s Burns Intensive Care Unit from 2009 to 2011 described their experience with the use of noninvasive positive pressure ventilation in patients with inhalational injuries.6 Eight out of 37 patients in the study had a diagnosis of chronic obstructive pulmonary disease (COPD); however, there was no further analysis or description of whether outcomes differed on the basis of underlying pulmonary status prior to inhalational injury.6 In a 2014 study, inhalational injury due to combustible tobacco product use while on home oxygen was examined, and patients with COPD had similar outcomes to those without underlying diagnosed lung disease.7 In 2022, a patient with COPD with underlying inhalation injury experienced prolonged, severe respiratory failure due to the inhalation of a mixed solution containing bleach and 2-butoxyethanol.8 Chemical inhalational injury results in significant dynamic hyperinflation requiring paralytics, steroids, nebulizers, and prolonged mechanical ventilation, highlighting the possibility of patients with underlying obstructive lung disease having an increased risk of bronchospasm.8 A single-site retrospective review examining 4397 patients with inhalational injury revealed that 515 had a diagnosis of COPD and 3882 did not have COPD. One study did not find a difference in the incidence of inhalational lung injury, length of stay, or number of ventilation days.9 The severity of burn size and lung injury correlated with increased mortality independent of COPD status.10 Overall, further studies are needed to further evaluate the impact of inhalational injury on patients with underlying lung disease. In our case of significant inhalational injury from smoke inhalation, given medical history of obstructive lung disease, the patient was treated with 5 days of prednisone 40 mg on admission, and triple inhaler therapy was initiated postextubation. The overall respiratory status improved significantly until day 10 of admission, when the patient presented with significant hypoxic and hypercarbic respiratory failure with an SpO2 of 70%, PCO2 > 100 mmHg, and unresponsiveness. Head computed tomography revealed no acute abnormalities. The patient was intubated and placed on mechanical ventilation. Ventilator waveform analysis revealed prolonged expiration and notable persistent airflow at the end of expiration, requiring a reduction in the respiratory rate to allow complete expiration and minimize autoPEEP. Computed tomography chest imaging (Figure 1) revealed upper lobe volume loss, fibrotic changes, and calcified lymph nodes, consistent with underlying sarcoidosis. Given the concern for ongoing exacerbation of obstructive lung disease, intravenous methylprednisone was administered, followed by bronchoscopy with bronchoalveolar lavage. Bronchoalveolar lavage was notable for bronchial cultures positive for Pseudomonas aeruginosa, so piperacillin-tazobactam was started. The patient clinically improved and was extubated on day 12 after admission. Postextubation, she was transitioned to prednisone 40 mg and then reduced to 20 mg for 2 weeks, with plans to taper it by 5 mg every week until her outpatient pulmonary appointment was scheduled 2 weeks after discharge. Inpatient pulmonary function tests revealed significant impairment, with a forced expiratory volume in one second/forced vital capacity ratio of 0.51, a forced expiratory volume in one second of 0.8 L (39% predicted), a forced vital capacity of 1.56 (61% pred), a normal TLC with a residual volume of 2.77 (148% pred), and a severely impaired DLCO of 6.09 (31.4% predicted). After a 25-day hospitalization, she was discharged with ongoing outpatient pulmonary care.Figure 1: Computed tomography scan of the thorax during admission.Six months later, the patient returned to her prehospitalization functional state. She remains on 2 L chronic oxygen therapy and is compliant with triple inhaled therapy. In summary, our patient experienced persistent airflow obstruction beyond the first week postinjury, which was particularly aggravated by bacterial ventilator-associated pneumonia and improved with prolonged steroid tapering. Further research in this area is needed to guide the complex management of these severely ill patients. The management of exacerbations in patients with underlying obstructive lung disease may require prolonged treatment with extended courses of steroids and bronchodilators, as well as mucolytics, to prevent mucus plugging postmucosal injury.1 This article also underscores the importance of considering the risk of developing severe air trapping and dynamic hyperinflation. Vigilant monitoring for signs of severe bronchospasm and appropriate individualized ventilatory strategies, including a lower respiratory rate, paralytics, or even helium–oxygen combination gas, may be necessary (Figure 2).Figure 2: Management of acute inhalational injury in patient with underlying obstructive lung disease.ARDS: Acute respiratory distress syndrome.In conclusion, the management of inhalational injury in patients with underlying chronic lung disease requires a tailored approach. Addressing both the acute effects of inhalational injury and the more prolonged impact of the exacerbation of underlying lung conditions—utilizing bronchodilators, airway clearance techniques, and corticosteroids—is critical. JJR is a shareholder in Globin Solutions Inc. JJR is a coinventor of provisional, pending, and granted patents for the use of recombinant neuroglobin and other heme-based molecules as antidotes for carbon monoxide poisoning and sodium nitrite for smoke-inhalation. JJR is an officer of Globin Solutions. JJR is a director of Globin Solutions. JJR is a cofounder of Omnibus Medical Devices LLC. The financial conflicts of interest of JJR are managed by the University of Maryland Baltimore Conflict of Interest Committee. This work is supported in part by the National Institutes of Health (grant K08 HL136857 to JJR).