Hypothyroidism in a Patient Presenting with Torsion of an Ovarian Cyst and a Possible Difficult Airway
March 21, 2010 by admin · Leave a Comment
Authors: Andrew Cocchiarella, MD, Shaheen Shaikh, MD, William Frost, DO, and Stephen O. Heard, MD
Department of Anesthesiology, University of Massachusetts Medical School, Worcester, MA
Introduction
| A 17-year-old female with a history of untreated hypothyroidism, familial pseudohypoparathyroidism and morbid obesity presented to the emergency room with nausea, vomiting and severe diffuse abdominal pain. After evaluation by the pediatric surgical team, she was scheduled for emergency exploratory laparotomy. |
Preoperative evaluation
| The patient’s longstanding hypothyroidism was secondary to familial pseudohypoparathyroidism that was also present in her mother, grandmother and maternal uncle. She was diagnosed with these endocrine disorders at age 8 and, due to noncompliance on the part of her family, was never effectively treated or followed. Her past medical history was also significant for developmental delay and morbid obesity (height 60”, weight 117 kg, BMI 50). She reportedly snored, but did not have apneic episodes while sleeping. Of note, she was actively vomiting while being evaluated by the anesthesia team.The patient was not cooperative with the physical examination and was unable to lie flat due to dyspnea. She was tachycardia (118/min) and hypotensive (77/36). Her respiratory rate was 18 and her oxygen saturation was 98% on room air. Her airway examination revealed a large tongue, Mallampati Class III airway, and reduced thyromental distance and neck extension. She had very poor dentition, including multiple missing teeth. A large abdominal mass extended above the umbilicus. She had no obvious peripheral veins and her only intravenous access was via a 22 gauge peripheral IV.Preoperative laboratory studies revealed hyponatremia (132mEql/L), hyperkalemia (5.5mEql/L), hypocalcemia (ionized calcium 3.0 mg/dL) and hypothyroidism (TSH 15.1 mIU/L). The bicarbonate concentration was 21mmol/L and the anion gap was 12. The hematocrit was 44%. A CT scan of the abdomen revealed a massive intraabdominal cyst.
Given the combination of a full stomach and a possibly difficult airway, we considered performing an awake fiberoptic intubation. Her developmental delay and uncooperative demeanor, however, precluded this option. We decided to proceed with an inhalational induction with maintenance of spontaneous ventilation. The patient was given a bolus of crystalloid in the holding area and her hemodynamics improved. She was also given glycopyrrolate 0.2 mg IV, metoclopramide 10 mg IV, famotidine 20 mg IV and midazolam 2 mg IV and was brought to the operating room. |
Intraoperative course
The patient was positioned in a semi-upright position and standard ASA monitors were placed. Induction was first attempted by placing a mask with 8% sevoflurane in oxygen over her face, but she was combative and would not allow a tight seal. She was then given ketamine 110 mg IV in divided doses that enabled her to tolerate the mask. Cricoid pressure was maintained throughout the induction. A slow, smooth induction with maintenance of spontaneous respiration was accomplished, though she did become hypotensive requiring several bolus doses of phenylephrine. After insertion of a second peripheral IV (20-gauge), direct laryngoscopy was performed with a Macintosh 4 blade that revealed a grade II view. A 7.0 mm endotracheal tube was inserted atraumatically on the first attempt and its proper location was confirmed with auscultation and capnography. Rocuronium 50 mg IV was then given and cricoid pressure was released. Anesthesia was subsequently maintained with isoflurane 0.8 ET% in oxygen and air, supplemented by periodic bolus doses of fentanyl.Intraoperatively the patient was fluid resuscitated with 1500 ml of crystalloid during the first hour. Though her urine output was adequate (~2 mL/kg/hr), she required a phenylephrine infusion to maintain her systolic blood pressure above 100 mm Hg. The combination of untreated hypothyroidism, hyponatremia, hyperkalemia, hypotension and the stress of the surgery prompted us to consider an Addisonian crisis. Thus hydrocortisone 100 mg IV was given approximately one hour into the case. At the same time, an infusion of levothyroxine 200 mcg was given due to the concern about precipitating myxedema coma. During the second half of the three-hour case, the patient was weaned off the phenylephrine infusion. Oxygenation and ventilation were adequate throughout the case.
 Figure 1: The 35 x 40 cm, 11 kg ovarian mass after its removal. The surgical findings included torsion of the left ovary which contained a 35 x 40 cm, 11kg cystic mass (Figure 1). A left salpingo-oophorectomy was performed, along with an appendectomy, partial omentectomy and right oophoropexy. We had several concerns that prompted our decision to leave the patient intubated postoperatively, including the possibility of a prolonged recovery from anesthesia as well as the likelihood of high postoperative opioid requirements in the setting of altered respiratory responses to hypercapnia and hypoxia due to hypothyroidism. |
Postoperative course
| In the pediatric intensive care unit (PICU), the patient was sedated with propofol and fentanyl infusions. On postoperative day 1, she was successfully extubated. She was followed closely by the pediatric endocrinology team who placed her on calcitriol and a calcium gluconate infusion. She continued to receive intravenous levothyroxine until she was able to take it by mouth. Her sodium and potassium concentrations rapidly normalized and she remained normotensive throughout her PICU course. Accordingly, stress-dose steroids were not continued. With the exception of persistent hypocalcemia (7.4 mg/dL), she was discharged home on postoperative day 6 with otherwise normal electrolyte concentrations. |
Discussion
| Familial pseudohypoparathyroidism is a rare form of hypoparathyroidism that is due to resistance of peripheral tissues to the effects of parathormone. It is associated with a phenotype characterized by short stature, obesity, developmental delay, round face, dental hypoplasia and short metacarpals and metatarsals. The primary anesthetic concern in hypoparathyroidism is hypocalcemia, which can be profound. Most patients with pseudohypoparathyroidism Type 1A (the subtype implicated in this case) also have primary hypothyroidism.
The ideal preoperative management of hypothyroidism consists of restoration of normal thyroid status. Patients receiving T3 should take their usual dose on the day of surgery due to its relatively short half-life of 1.5 days. T4, however, has a long half-life of 7 days and its administration on the morning of surgery can be considered optional. The anesthetic implications of hypothyroidism depend on the severity of the condition. Patients with markedly decreased serum T3 and T4 levels, those who manifest any severe clinical symptoms of chronic hypothyroidism, or those with myxedema coma are all at increased risk of having complications during the perioperative period. In general, untreated hypothyroidism decreases anesthetic requirements slightly. Patients may be profoundly sensitive to opioids that may be associated with prolonged recovery from anesthesia or may precipitate hypothyroid coma. Volatile agents should be used cautiously as even low concentrations may produce profound hypotension and exacerbate hypothermia. Incipient or overt hypothyroid coma is an indication for urgent perioperative thyroid hormone replacement, usually 200-400 mcg of intravenous levothyroxine (T4) followed by 100 mcg daily or 10-25 mcg of intravenous triiodothyronine (T3) every 8 hrs. Hypothyroid patients also have an increased incidence of adrenocortical insufficiency and may not mount an appropriate adrenocorticotropic hormone response to stress. Thus, stress-dose steroid coverage may be required during the perioperative period. Finally, the need for prolonged ventilatory support must be anticipated as recovery from anesthesia may be substantially delayed in hypothyroid patients. This case was challenging because of its emergent nature, the unclear severity of the patient’s longstanding hypothyroidism, and the possibility of a difficult airway in an uncooperative patient with known developmental delay. An awareness of the anesthetic implications of untreated hypothyroidism may assist in providing a good outcome in cases like this. |
References
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Case Discussion
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