DOI: 10.12890/2026_006904

Defying an ominous sign: complete neurological recovery after bilateral fixed dilated pupils in hypercapnic respiratory failure

Authors

  • Sody A. Naimer Department of Family Medicine, Siaal Family Medicine and Primary Care Research Center, Haim Doron Division of Community Health, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel; Department of Emergency Medicine, Beilinson Medical Center, Petach Tikva, Israel 0000-0003-2614-147X

sodynaster@gmail.com

Keywords

Bilateral fixed dilated pupils, hypercapnic respiratory failure, pupillary abnormalities, prognostication, respiratory acidosis

Abstract

Introduction: Bilateral fixed dilated pupils (BFDP) have traditionally been regarded as an ominous sign indicating severe brainstem dysfunction and poor neurological prognosis, often prompting discussions regarding withdrawal of life-sustaining treatment. However, pupillary abnormalities can also result from reversible metabolic derangements, including severe hypercapnia, profound acidosis, and hypoxia. Current guidelines emphasize that pupillary assessment should occur after correction of confounding factors such as hypoxemia, hypotension, and metabolic disturbances.
Case description: A 66-year-old man with a history of ischemic stroke six months prior presented with prolonged generalized seizures, vomiting, and progressive loss of consciousness. On arrival to the Emergency Department, he was unconscious with bilaterally dilated, unreactive pupils. Venous blood gas analysis revealed severe respiratory acidosis with pH 6.96 and pCO2 102 mmHg. Despite intubation and mechanical ventilation, he developed profound desaturation followed by cardiac arrest with ventricular tachycardia requiring cardioversion. A brain computed tomography scan showed no new intracranial pathology. Chest radiography demonstrated massive bilateral aspiration pneumonia. Following aggressive resuscitation, mechanical ventilation, broad-spectrum antibiotics, and supportive care, his respiratory parameters and acidosis gradually improved. As his respiratory status normalized, his pupils became constricted and reactive to light. The patient was successfully weaned from mechanical ventilation and regained full consciousness with complete restoration of cognitive function.
Conclusion: Bilateral fixed dilated pupils in severe hypercapnic respiratory failure may be a transient and fully reversible phenomenon when driven by metabolic derangements rather than structural brain injury. Timely resuscitation and deferral of definitive prognosis until confounding metabolic factors have been corrected is essential to avoid premature withdrawal of life-sustaining treatment.

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References

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Published

2026-08-24

Issue

Vol. 13 No. 9 (2026)

Categories

How to Cite

1.
Naimer SA. Defying an ominous sign: complete neurological recovery after bilateral fixed dilated pupils in hypercapnic respiratory failure. EJCRIM [Internet]. 2026 Aug. 24 [cited 2026 Nov. 3];13(9). Available from: https://ejcrim.com/index.php/ejcrim/article/view/6904