FENTANYL-INDUCED PERSISTENT ENCEPHALOPATHY

Abstract

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Fentanyl is a synthetic opioid routinely used for sedation and analgesia in the intensive care unit (ICU). Though typically safe when used vigilantly for ICU-level care, it can sometimes cause serious adverse effects such as acute encephalopathy that usually improve with supportive care. We present a rare case of persistent encephalopathy caused by fentanyl. CASE PRESENTATION: An 85-year-old functionally independent woman with a history of chronic obstructive pulmonary disease (COPD) on 2 L oxygen, hypertension, and hypothyroidism presented with shortness of breath and dry cough for four days. She was intubated and mechanically ventilated for worsening respiratory distress and hypercapnia. She required deep sedation with maximum doses of fentanyl infusion 200 mcg/hr and propofol infusion 60 mcg/kg/min, and vasopressor support with norepinephrine for two days to maintain her blood pressure. Sputum cultures grew Haemophilus influenza. She was treated with 7 days of intravenous levofloxacin for tracheobronchitis and COPD exacerbation. She also received intravenous methylprednisolone and breathing treatments. Her respiratory status gradually improved and she was weaned down to minimal ventilator FiO2 and PEEP and sedation in five days, but she stayed unresponsive. Seven days off sedation, she had a partial return of consciousness but had altered mentation, quadriplegia, and absence of reflexes bilaterally. She showed minimal response to painful stimuli in all limbs. CT and MRI of the head and C-spine showed no acute pathology. Cerebrospinal fluid analysis and cultures ruled out infectious (including viral, bacterial, and fungal) etiologies. 12-hour EEG was consistent with metabolic encephalopathy. After multidisciplinary evaluation, her encephalopathy was attributed to fentanyl. Patient was eventually extubated after 16 days. One month later, she had mild improvement of neurological status with orientation only to person. She was able to slightly squeeze examiner's fingers in both hands, and foot plantar and dorsiflexion was 4/5 bilaterally with the rest of motor strength 0/5 in all extremities. She was discharged to a nursing home with unchanged neurological status. DISCUSSION: Fentanyl has a rapid onset and short duration of action making it sedation of choice in ICU. Acute encephalopathy is infrequently associated with other synthetic opioids like oxycodone and methadone [1,2]. Fentanyl uncommonly causes delayed hypoxic leukoencephalopathy which develops few days to weeks after exposure [3]. Acute persistent encephalopathy from fentanyl is rare and can lead to significant functional impairment. CONCLUSIONS: It is important for clinicians to be aware of persistent encephalopathy caused by fentanyl. Sedation should be used with caution especially in elderly patients. Intermittent pushes or shorter duration of use may prevent this rare complication. REFERENCE #1: Morales Odia Y, Jinka M, Ziai WC. Severe leukoencephalopathy following acute oxycodone intoxication. Neurocrit Care. 2010;13(1):93-97. REFERENCE #2: Haghighi-Morad M, Naseri Z, Jamshidi N, Hassanian-Moghaddam H, Zamani N, Ahmad-Molaei L. Methadone-induced encephalopathy: a case series and literature review. BMC Med Imaging. 2020;20(1):6. REFERENCE #3: Kim J, Hyung SW, Seo J, Lee H, Yu HJ, Sunwoo MK. Delayed post-hypoxic leukoencephalopathy caused by fentanyl intoxication in a healthy woman. Dement Neurocognitive Disord. 2020;19(4):170-172. DISCLOSURES: No relevant relationships by Qasim Jehangir, source=Web Response No relevant relationships by Yi Lee, source=Web Response No relevant relationships by Ali Najar, source=Web Response No relevant relationships by Jonathan Toot, source=Web Response