C48-03 Delayed Weaning From V-V ECMO Due to Acute Hypothyroidism From Neck Trauma

Introduction Weaning from VV ECMO requires recovery of native lung oxygenation and ventilation. We present a case where neck trauma caused an acute episode of hypothyroidism that delayed successful ECMO decannulation due to decreased respiratory drive. Case Description A 17 year-old boy was transferred for evaluation of severe ARDS and possible VV ECMO 6 days after being ejected during an MVC. His injuries included rib fractures with pulmonary contusions, extensive full-thickness abrasions of torso/hips/lower extremities, T-spine and clavicle fractures, and multiple facial/jaw fractures with lacerations to face and neck. Aspiration of blood and secretions occurred immediately post-injury and a surgical airway was attempted at the OSH with aggressive neck incisions. He arrived on ARDSnet settings paralyzed, deeply sedated on Norepinephrine and Vasopressin with blood cultures showing Klebsiella Pneumoniae. SaO2 70% with pO2 50 and pCO2 70; lactic acid >10 with AKI, acute hepatic dysfunction and evidence of DIC. VV ECMO was initiated emergently with immediate improvement of gas exchange but ongoing hypotension due to vasodilation with preserved cardiac output due to low SVR so hydroxocobalamin was administered. He had recovery of his multi-organ failure with CXR and oxygenation improving rapidly while using ARPV-TCAV strategy on MV FiO2 21%. He was able to tolerate 1 hour recirculation trials starting on day 9 while MV FiO2 of 21-25% but his pCO2 rose acutely without any increase in his respiratory response. TSH resulted at 9.720 MIU/L with FT4 0.47 NG/DL and T3F 1.8 PG/ML confirming acute hypothyroidism presumably due to his neck injuries and subsequent iatrogenic procedures that included attempted cricothyroidotomy at the OSH and an open tracheostomy with division of the thyroid isthmus at our center. Thyroxine was administered intravenously and after three days a recirculation trial was conducted for 24 hours and he was successfully decannulated on ECMO day 14. Thyroid function normalized and thyroxine was stopped 2 weeks later. Liberated from MV and after a short rehab stay, he was discharged home on room air. Discussion Hypothyroidism is associated with hypercarbia through a depressed central respiratory drive. Thyroid hormones help regulate the respiratory centers in the brainstem so that low thyroid hormone levels reduce the sensitivity of these centers to changes in carbon dioxide. Hypothyroidism should be considered when hypercarbia is found associated with a low minute ventilation and sedatives or other medications that may reduce the respiratory drive have been excluded as well as neuromuscular disorders.