Lippincott's Anesthesia Review: 1001 Questions and Answers

Chapter 15. Endocrine Diseases

Jean Kwo and Edward Bittner

    1.   Type 1 diabetes mellitus

          A.   Is characterized by a relative lack of insulin plus resistance to endogenous insulin

          B.   Always requires insulin

          C.   Affects 95% of patients with diabetes

          D.   Can be controlled with diet, weight loss, and oral hypoglycemic agents

    2.   Preoperative assessment of patients with diabetes mellitus should include

          A.   An assessment of functional status

          B.   24-Hour creatinine clearance

          C.   Pulmonary function testing

          D.   Cancellation of the surgical case if HbA1c >10%

    3.   Preferred anesthetic agent in a patient with hyperthyroidism includes

          A.   Desflurane

          B.   Ketamine

          C.   Sevoflurane

          D.   Meperidine

    4.   Multiple endocrine neoplasia (MEN) I syndrome includes

          A.   Pheochromocytoma, medullary thyroid carcinoma, parathyroid hyperplasia

          B.   Pancreas tumors, medullary thyroid carcinoma, pituitary adenoma

          C.   Pheochromocytoma, medullary thyroid carcinoma, mucosal neuromas

          D.   Pancreas tumors, pituitary adenoma, parathyroid hyperplasia

    5.   Laboratory findings in primary hypothyroidism are

          A.   Low TSH, elevated T3, elevated T4

          B.   Low TSH, low T3, low T4

          C.   Normal TSH, low T3, low T4

          D.   Elevated TSH, low T3, low T4

    6.   Obese patients may experience rapid oxygen desaturation during induction of general anesthesia because of

          A.   A decrease in lung compliance

          B.   A reduction in functional residual capacity (FRC)

          C.   A history of obstructive sleep apnea

          D.   Restrictive lung disease

    7.   A 39-year-old woman with a history of headaches, hypertension, palpitations, and nephrolithiasis is undergoing a parathyroidectomy for parathyroid adenoma. During induction, she develops severe hypertension and tachycardia. The most likely diagnosis for these signs is

          A.   Adrenal insufficiency

          B.   Carcinoid syndrome

          C.   Thyroid storm

          D.   Pheochromocytoma

    8.   Phenoxybenzamine is a

          A.   Selective α1-receptor antagonist and a nonselective β-adrenergic receptor antagonist

          B.   Reversible α1-receptor antagonist

          C.   Irreversible, nonselective α-adrenergic receptor antagonist

          D.   Selective α2-receptor agonist

    9.   A 40-year-old woman with a history of Graves disease is in the recovery room after undergoing a CT scan under general anesthesia. While in the recovery room, her blood pressure drops to 80/55 mm Hg, her heart rate increases to 140 bpm, and she becomes agitated and complains of difficulty breathing and feeling hot. The most likely diagnosis for these signs is

          A.   Thyroid storm

          B.   Carcinoid syndrome

          C.   Malignant hyperthermia

          D.   Pheochromocytoma

  10.   Treatment of thyroid storm includes

          A.   Dantrolene

          B.   Phenoxybenzamine

          C.   Octreotide

          D.   Propylthiouracil

  11.   During a postoperative check on a 53-year-old patient who underwent a total thyroidectomy earlier in the day, you notice that he is stridorous and is complaining of muscle cramps. The best treatment for these symptoms is

          A.   Administration of calcium gluconate

          B.   Opening the neck wound

          C.   Reintubation for airway protection

          D.   Administration of sodium bicarbonate

  12.   Patients with obstructive sleep apnea (OSA)

          A.   Are at increased risk of left-heart failure

          B.   Have the same perioperative complication rate as patients without OSA

          C.   May have an increased likelihood of difficult intubation

          D.   Rarely require continuous positive airway pressure (CPAP) after bariatric surgery

  13.   A 39-year-old patient with a BMI of 45 kg/m2 is scheduled for a Roux-en-Y gastric bypass. She has a history of hypertension. Your perioperative concerns include

          A.   Preparation for a rapid sequence induction, since she is at increased risk for aspiration of gastric contents

          B.   Placing her in the reverse Trendelenburg position to reduce atelectasis in dependent areas of the lung and move the chest and breast tissue caudally to allow easier access to the mouth for endotracheal intubation

          C.   Need to dose water-soluble drugs (e.g., neuromuscular-blocking agents) to actual body weight

          D.   More frequent administration of lipid-soluble drugs will be needed

  14.   During the preoperative evaluation of a critically ill patient with ischemic bowel scheduled for a second look laparotomy and possible abdominal closure, you notice multiple electrolyte abnormalities including hypophosphatemia, hypokalemia, and hypomagnesemia. A possible cause for these electrolyte abnormalities is

          A.   Renal failure

          B.   Hypoventilation

          C.   Hypoparathyroidism

          D.   Refeeding syndrome

  15.   Complications of cricoid pressure include

          A.   Esophageal obstruction

          B.   Displacement of thoracic spine

          C.   Worsening of view of airway in patients with difficult airway

          D.   Need for less pressure in parturients

  16.   You are evaluating a 55-year-old patient with type 2 diabetes mellitus for a total knee replacement. His diabetes is controlled on a regimen of Glucophage (metformin), NPH insulin twice a day, and insulin sliding scale. Perioperative instructions for glucose management should include

          A.   Give half of the NPH dose if morning blood glucose level is at least 150 mg/dL

          B.   Give regular insulin dose according to morning blood glucose level

          C.   Holding metformin for 48 hours preoperatively to avoid risk of fatal lactic acidosis

          D.   Starting insulin infusion with target glucose range of 81 to 108 mg/dL

  17.   Carcinoid tumors

          A.   Grow rapidly, and patients are often symptomatic with carcinoid syndrome

          B.   Synthesize epinephrine and norepinephrine

          C.   Can cause left-sided heart failure due to mitral and aortic valve damage

          D.   Can cause right-sided heart failure due to tricuspid and pulmonary valve damage

  18.   You are taking care of a 67-year-old patient undergoing a parathyroidectomy. The patient is hypercalcemic with a serum calcium of 20 mg/dL. Anesthetic considerations should include all of the following, except

          A.   Hypoventilation to decrease ionized calcium level

          B.   Careful titration of neuromuscular-blocking agents

          C.   Hydration with normal saline and diuresis with furosemide

          D.   Care with laryngoscopy because of risk of vertebral compression

  19.   Clinical manifestations of mineralocorticoid excess include

          A.   Hypotension

          B.   Metabolic acidosis

          C.   Hypokalemia

          D.   Tetany

  20.   Normal daily cortisol production (mg/day) in adults is

          A.   10 to 15

          B.   20 to 30

          C.   50 to 60

          D.   75 to 100

  21.   A 75-year-old patient with coronary artery disease, hypertension, and chronic obstructive pulmonary disease (COPD) is undergoing a left colectomy for cancer. He had a COPD exacerbation 4 months ago and was on steroids for a week at the time. Steroid replacement

          A.   Should be given at a dose greater than 10 times the normal daily cortisol production rate

          B.   Should not exceed 100 to 150 mg of cortisol equivalent per day

          C.   Is not necessary in this patient

          D.   Should include 100 mg of cortisol, tapered over 5 to 7 days

  22.   Physiologic effects of chronically elevated corticosteroid levels (Cushing syndrome) include all of the following, except

          A.   Hypotension

          B.   Muscle wasting

          C.   Hypokalemia

          D.   Glucose intolerance

  23.   You are taking care of a 45-year-old patient undergoing a left adrenalectomy for a pheochromocytoma. Intraoperative management includes

          A.   Use of ketamine as an induction agent to counteract the effects preoperative of α-adrenergic blockade

          B.   Long-acting antihypertensive agents should be available to treat hypertension

          C.   Judicious fluid replacement as these patients are usually volume-overloaded

          D.   Magnesium sulfate infusion to treat hypertension

  24.   A 75-year-old, 110-kg patient is scheduled for a radical prostatectomy. He has a history of hypertension and type 2 diabetes mellitus. His preoperative ECG is significant for Q waves in leads II, III, and aVF, though the patient denies having a previous myocardial infarction. His medications include insulin, Glucophage (metformin), a β-blocker, and an angiotensin-receptor blocker. Upon induction, his blood pressure drops from 150/80 to 65/40. The most likely cause of hypotension is

          A.   Use of angiotensin-receptor blocker

          B.   Diabetic autonomic neuropathy

          C.   Volume depletion

          D.   Myocardial ischemia

  25.   Patients with type 1 diabetes mellitus may be difficult to intubate because of

          A.   Increased supraglottic soft tissue due to chronic hyperglycemia

          B.   An association between type 1 diabetes and an anterior larynx

          C.   Limited joint mobility

          D.   An increased incidence of obesity in patients with type 1 diabetes

CHAPTER 15 ANSWERS

    1.   B.      Type 1 diabetes mellitus results from the autoimmune destruction of insulin-producing β cells of the pancreas and thus these patients always need insulin to prevent hyperglycemic ketoacidosis and other complications. Most patients carrying the diagnoses of diabetes (95%) have type 2 diabetes, which is characterized by a relative lack of insulin plus resistance to endogenous insulin. Type 2 diabetes can be controlled with diet and weight loss, and oral agents, though these patients may also require insulin.

    2.   A.      Complications of diabetes result largely from microangiopathy and macroangiopathy. Diabetes is a well-recognized risk factor for coronary artery disease (CAD). Cardiac autonomic neuropathy may mask angina pectoris and obscure the presence of CAD. Hence, a careful assessment of functional status and any symptoms such as increasing dyspnea on exertion and fatigue may be indicative of significant CAD. While diabetes is a leading cause of renal failure, there is no evidence that a preoperative evaluation with a 24-hour creatinine clearance is helpful. While the risk of complications of diabetes increases with increasing HbA1c levels, and there is evidence that higher HbA1c levels are associated with adverse outcomes following a variety of surgical procedures, there is insufficient evidence to recommend an upper limit of HbA1c prior to elective surgery. The risks associated with poor glycemic control should be balanced against the necessity for surgery.

    3.   C.      In patients with hyperthyroidism, the goal of anesthesia is to avoid an increase in heart rate or sympathetic activation. Ketamine, desflurane, and meperidine cause sympathetic stimulation and tachycardia. Conversely, anesthetics and techniques that reduce or blunt sympathetic activity are preferred. Sevoflurane for anesthesia, and fentanyl and its congeners for analgesia would be favored. Regional anesthesia, when practical, might also be efficacious in avoiding sympathetic activation.

    4.   D.      MEN I syndrome includes the triad of tumors of the pancreas, pituitary, and parathyroid glands and is inherited as an autosomal-dominant trait. Medullary thyroid carcinomas are a component of the MEN II endocrine syndromes, of which there are several subtypes.

    5.   D.      

Table 15-1

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    6.   B.      Obesity is associated with obstructive sleep apnea, decreased pulmonary compliance, and lung volumes suggestive of restrictive lung disease. Total pulmonary compliance decreases due to a decrease in both chest-wall compliance and lung compliance. Chest-wall compliance decreases because of excessive adipose tissue over the thorax, while lung compliance decreases because of the increased abdominal mass, which pushes the diaphragm cephalad causing an increase in pulmonary blood volume. The FRC of the lung is the volume of air present in the lungs at the end of passive expiration and reflects a balance between the elastic recoil of the lungs and the pleural pressure. With obesity, there is a shift in this balance due to adipose tissue in the chest wall and abdomen, resulting in a decreased FRC. The FRC is the reservoir of oxygen during the apneic state associated with the induction of general anesthesia. Thus, the reduction of FRC associated with obesity results in greater oxygen desaturation during the induction of general anesthesia.

    7.   D.      While inadequate anesthesia and thyroid storm may result in intraoperative hypertension and tachycardia, the most likely diagnosis is pheochromocytoma. Pheochromocytoma is a catecholamine-secreting tumor and is part of the multiple endocrine neoplasia (MEN) type II syndrome, which consists of pheochromocytoma, medullary thyroid carcinoma, and parathyroid adenoma. Symptoms associated with pheochromocytoma include paroxysmal headache, hypertension, diaphoresis, and palpitations.

    8.   C.      Phenoxybenzamine is an irreversible, nonselective α-adrenergic receptor antagonist used preoperatively for adrenergic blockade in patients with pheochromocytomas. It blocks both the postsynaptic α1 and presynaptic α2receptors in the nervous system, thereby reducing sympathetic activity. Clinical signs of the optimal dose of phenoxybenzamine are a stuffy nose and slight dizziness due to postural hypotension. Doxazosin is a reversible, selective α1-receptor antagonist that is an alternative to phenoxybenzamine for treatment of pheochromocytoma. In patients with pheochromocytoma, α-blockade is always started prior to β-blockade. Starting β-blockade first will lead to unopposed α stimulation causing further increase in the blood pressure.

    9.   A.      Thyroid storm is characterized by fever, tachycardia, altered mental status, and hypertension, presenting most often in the postanesthesia care unit or in the immediate postoperative period (24 hours). Hypertension may be followed by congestive heart failure that is associated with hypotension and shock. Thyroid storm is a state of severe hypermetabolism induced by excessive release of thyroid hormones. It can be precipitated by surgery, stress, infection, and drugs including chemotherapeutic agents, anticholinergic, and adrenergic drugs such as pseudoephedrine, amiodarone, and iodinated contrast media. Unlike malignant hyperthermia, it is not associated with muscle rigidity, an elevated creatinine kinase, or acidosis.

  10.   D.   Thyroid storm is a medical emergency and if untreated, often fatal. Supportive treatment includes cooling, hydration, and β-blockers to control heart rate. Propranolol has the additional benefit of inhibiting the peripheral conversion of T4–T3. Propylthiouracil and methimazole inhibit the synthesis of T4 by blocking the organification of tyrosine residues. Iodide blocks the release of preformed thyroid hormones, but it should be given only after the loading dose of antithyroid medication to prevent the utilization of iodine in the synthesis of new thyroid hormones. Administration of cortisol is also recommended to prevent complications from potential coexisting adrenal insufficiency.

  11.   A.   Hypoparathyroidism resulting from the unintentional removal of the parathyroid glands is a potential complication of thyroidectomy. Low blood calcium levels interfere with normal muscle contraction and nerve conduction, and can result in muscle cramps, weakness, tetany, laryngospasm, and stridor. Treatment consists of normalizing the serum calcium level with intravenous calcium. While a neck hematoma can cause airway compromise due to compression, it is unlikely to cause muscle cramps. Stridor due to bilateral vocal cord paralysis is evident immediately on extubation and would require reintubation to establish a patent airway. Sodium bicarbonate would cause a metabolic alkalosis and potentially worsen symptoms of hypocalcemia by decreasing ionized calcium levels.

  12.   C.   Patients with OSA may have an increased likelihood of difficult intubation, since the upper airway abnormalities associated with OSA (increased neck circumference, large tongue, decreased cross-sectional area of the upper airway) may also predispose to difficult intubation. Hypercapnia associated with severe OSA can lead to right-heart failure. OSA is associated with increased perioperative complications including cardiac arrhythmias, hypertension, myocardial ischemia, respiratory failure, and stroke. Supine positioning and sedative agents make the upper airway even more prone to obstruction. Thus, patients with OSA may require CPAP in the immediate postoperative period.

  13.   B.   Preoperative preparation is essential for caring for the obese patient. Perioperative concerns include difficult intravenous access, possible need for arterial blood pressure monitoring, positioning, difficult endotracheal intubation, and appropriate dosing of medications. Nondiabetic obese patients are not at increased risk of aspiration of gastric contents, as they may have smaller gastric fluid volumes at higher pH than do lean nondiabetic patients. However, obesity may increase the risk of a difficult laryngeal intubation, especially in males and patients with a higher Mallampati score. Placement of the patient in the reverse Trendelenburg position during intubation is advantageous because it reduces atelectasis, increases time to oxygen desaturation after preoxygenation, and moves the chest and abdominal tissue caudally to allow easier access to the mouth for endotracheal intubation. Obese patients have a smaller volume of distribution for water-soluble drugs. Thus, dosing of these drugs should be based on ideal body weight to avoid overdosing. Larger fat stores provide an increased volume of distribution for lipid-soluble drugs. For lipid-soluble drugs, while a loading dose should be based on actual body weight, clearance will be slower because of the larger volume of distribution, and thus, maintenance doses should be administered less frequently.

  14.   D.   Refeeding syndrome can occur in malnourished patients who are acutely fed (either enterally or parenterally). It is caused by increased adenosine triphosphate production and metabolic rate. Hypophosphatemia is the hallmark biochemical feature of refeeding syndrome. Other metabolic and electrolyte disturbances may include abnormal sodium and fluid balance; hypokalemia; hypomagnesemia; thiamine deficiency; and changes in glucose, protein, and fat metabolism. Refeeding syndrome can be avoided by slowly increasing the nutritional intake toward caloric goals.

  15.   C.   Cricoid pressure can be associated with several complications. These complications are more likely in the elderly, children, pregnant women, patients with cervical injury, patients with difficult airways, and when there is difficulty palpating the cricoid cartilage. The technique involves the application of backward pressure on the cricoid cartilage to occlude the esophagus and thus prevents the aspiration of gastric contents during induction of anesthesia. However, strong downward pressure can also displace an unstable cervical spine and worsen visualization of the airway by occluding the glottis. In contrast, parturients may need more pressure to effectively occlude the esophagus.

  16.   A.   The primary goal of intraoperative blood sugar management is to avoid hypoglycemia. The most common perioperative management regimen consists of giving the patient a fraction (usually half) of the morning intermediate-acting insulin dose. If hypoglycemia is a concern, an infusion of dextrose may be started. Short-acting insulin preparations are held because of an increased risk of hypoglycemia and their short duration of action. Metformin has a duration of action of 6 to 24 hours (up to 48 hours with the extended release formulation). While it was previously recommended that metformin be discontinued 48 hours preoperatively to avoid risk of fatal lactic acidosis, more recent data suggest that this risk is low. The optimal level of glucose control in the perioperative setting remains controversial. The American Association of Clinical Endocrinologists (AACE) and the American Diabetes Association (ADA) recommend keeping blood glucose between 140 and 180 mg/dL in critically ill patients. For noncritically ill patients treated with insulin, premeal glucose targets should generally be <140 mg/dL and random blood glucose values should be <180 mg/dL. The NICE-SUGAR trial in critically ill patients showed an increased mortality and increased incidence of severe hypoglycemia in patients randomized to intensive glucose control (target glucose range 81–108 mg/dL).

  17.   D.   Carcinoid tumors are slow-growing tumors that secrete serotonin, kallikrein, and histamine. Excess serotonin secretion can result in carcinoid syndrome, which is characterized by diarrhea, flushing, palpitations, and bronchoconstriction. However, most patients with carcinoid tumors are not symptomatic because the liver detoxifies the excess serotonin. Patients are symptomatic if they have tumors arising outside of the hepatic portal venous system or when liver metastatic disease has compromised hepatic synthetic function. The sclerosing effect of serotonin on the tricuspid and pulmonary valves can result in right-heart failure. The left heart is generally not affected because of lung metabolism of serotonin. Preoperative echocardiography should be considered in patients with carcinoid syndrome.

  18.   A.   Patients with a serum calcium >14 mg/dL should be managed with saline and diuresis to decrease their calcium level. Neuromuscular-blocking agents should be titrated carefully as severe hypercalcemia can result in muscle weakness. Prolonged hypercalcemia can result in osteoporosis and risk of vertebral compression fractures with laryngoscopy and bone fractures during transport. Hypoventilation should be avoided as acidosis increases ionized calcium levels.

  19.   C.   Hypersecretion of aldosterone results in increased sodium reabsorption in the distal renal tubule in exchange for potassium and hydrogen ions. This results in fluid retention, hypertension, metabolic alkalosis, hypokalemia, and muscle weakness.

  20.   B.   Adults normally secrete 20 to 30 mg of cortisol daily. This may increase to over 300 mg under conditions of stress.

  21.   C.   Patients who have received the equivalent of 5 mg of prednisone or more for a period of more than 2 weeks within the previous 3 months may not be able to respond appropriately to surgical stress due to adrenal suppression. These patients should receive perioperative steroid replacement therapy. The dose of steroids needed is controversial though. One recommended approach is to give a dose between 1 and 5 times the daily cortisol production (no more than 100 to 150 mg of cortisol equivalent) per day, beginning at the time of surgery and taper the replacement over 48 to 72 hours.

  22.   A.   Cushing syndrome is characterized by muscle weakness/wasting, glucose intolerance, hypertension, hypokalemia, weight gain, hypercoagulability, and osteoporosis.

  23.   D.   Intraoperative management of pheochromocytoma resection includes avoidance of drugs (e.g., ketamine, ephedrine) or techniques that may stimulate the sympathetic nervous system. Intubation should be performed after a deep level of anesthesia is achieved and hypoventilation should be avoided. Despite adequate preoperative α- and β-blockade, hypertension may still occur. These should be treated with short-acting, easily titrated agents such as nitroprusside or nicardipine. Phentolamine may also be useful because it blocks α-adrenergic receptors. Magnesium infusions have been shown useful in managing hypertension by inhibiting catecholamine release and by altering adrenergic receptor response. Patients with pheochromocytomas are often hypovolemic and become hypotensive, and hypoglycemic (lack of catecholamine-induced glucose synthesis) after tumor ligation and resection.

  24.   B.   While all of the above may cause hypotension on induction of anesthesia, the most likely cause in this patient is diabetic autonomic neuropathy. Diabetic patients with hypertension, longstanding diabetes, coronary artery disease, and old age are more likely to have autonomic dysfunction. Patients with autonomic neuropathy are unable to compensate for intravascular volume changes with an increased heart rate, and thus are more likely to have hemodynamic instability and even sudden cardiac death. This risk is increased by concomitant use of β-blockers, angiotensin-converting enzyme inhibitors, and angiotensin-receptor blockers.

  25.   C.   Limited joint mobility syndrome is due to glycosylation of tissue proteins due to chronic hyperglycemia. It is characterized by hand stiffness, though other joints (wrists, elbows, feet, spine) may be involved. Involvement of the temporomandibular joint and the cervical spine can result in difficult endotracheal intubation.