1Junior Resident and Post Graduate, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
Email: lakshmimkrishna.364@gmail.com
2*Assistant Professor, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
Email: ajaypawardr@gmail.com
3Professor & Head of Department, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
4Senior Resident, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
5Junior Resident & Post Graduate, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
6Junior Resident & Post Graduate, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
7Junior Resident and Post Graduate, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
8Junior Resident and Post Graduate, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
9Junior Resident and Post Graduate, Department of Emergency Medicine, J.N Medical College, Belagavi, KLE Academy of Higher Education and Research, Deemed to be University, Belagavi, Karnataka, India 590010
10CMO, Alphonsa Hospital, Anakkara, Idukki, Kerala, India
Background: Carbon monoxide (CO) poisoning is a common and potentially life-threatening consequence of enclosed-space fires. Diagnosis is frequently delayed because conventional pulse oximetry may remain normal despite significant tissue hypoxia, a phenomenon termed silent hypoxia.
Aim: To describe the clinical presentation, physiological findings, management, and short-term outcomes of patients with suspected acute CO poisoning following an enclosed workplace fire.
Methods: This descriptive case series included ten female patients presenting to a tertiary care emergency department within eight hours of smoke exposure from an enclosed workplace fire. Clinical features, pulse oximetry, arterial blood gas (ABG) parameters, radiological findings, treatment, and outcomes were analyzed.
Results: All patients presented with neurological, respiratory, or gastrointestinal symptoms, most commonly altered sensorium and breathlessness. Pulse oximetry readings were normal in all cases (96–99% on room air). ABG analysis consistently demonstrated respiratory alkalosis with low PaCO₂ and reduced bicarbonate, while PaO₂ remained normal. Chest radiographs and ECGs were unremarkable. All patients received 100% oxygen via non-rebreather mask, resulting in rapid symptomatic improvement within 15–30 minutes. None required ventilatory support or hyperbaric oxygen therapy.
Conclusion: Normal pulse oximetry does not exclude carbon monoxide poisoning in enclosed-space fire exposure. Recognition of silent hypoxia and early administration of high-flow oxygen are essential for prompt recovery and favorable outcomes.
Keywords: Carbon monoxide poisoning, Silent hypoxia, Enclosed-space fire, Smoke inhalation, Workplace exposure, Pulse oximetry limitation, Respiratory alkalosis, Arterial blood gas, Oxygen therapy, Emergency medicine, Inhalational injury.
How to cite this article: Lakshmi M, Pawar A, Udapudi SV, Hatti MA, Anas TC, Haneef H, Unais M, Jishnu KS, Joji S, Iju M. Silent hypoxia unmasked: A case series of suspected acute carbon monoxide poisoning following an enclosed workplace fire. Int J Drug Deliv Technol. 2026;16(6s): 518-524; DOI: 10.25258/ijddt.16.6s.56
Source of support: Nil.
Conflict of interest: Nil