Obesity MCQS.pptx

MCQS in anaesthesia for obesity

1. Obesity MCQS

2. Chapter 1 57. Which of the following findings in the preoperative evaluation cannot be attributed to obesity with obstructive sleep apnea (OSA) in a patient planned for bariatric surgery? A. Pulmonary artery hypertension B. Congestive heart failure C. Peripheral neuropathy D. Dementia

3. 96. Which of the following is the best predictor of a difficult intubation in a morbidly obese patient? A. Pretracheal tissue volume B. Body mass index C. Mallampati score D. Thyromental distance

4. Chapter 7 26. You just placed a thoracic epidural in a morbidly obese female (5’1” and 350 lb ). You quickly administer a total of 20 mL 0.5% bupivacaine through the epidural catheter. As you reposition the patient from the sitting to the supine position, the patient complains of shortness of breath, bilateral arm weakness, and nausea. Her HR has decreased from a baseline of 98 to 41 bpm , and her systolic blood pressure has decreased from a baseline of 140s to 70s mm Hg. The most likely cause is A. Accidental intravascular injection of local anesthetic B. Local anesthetic systemic toxicity C. A high epidural block D. Anaphylactic reaction to local anesthetic or latex

5. Chapter 14 2. Each of the following would be expected in an otherwise-healthy 125-kg (BMI 40 kg/m2) man undergoing open cholecystectomy, except A. Decreased functional residual capacity B. Increased intra-abdominal pressure and risk of reflux C. Increased metabolism of volatile anesthetics D. Decreased metabolism of atracurium

6. 5. A morbidly obese 60-year-old man with a 65-pack year history of tobacco smoking is awake after an uncomplicated general anesthetic with sevoflurane for routine endoscopy and colonoscopy screening. After 45 minutes in the recovery room (PACU), while breathing 6 L/min of oxygen via nasal cannula, his pulse oximetry drops to 88%. His rest of the vital signs are stable, and the lungs are clear to auscultation. The most effective management at this point is A. Coughing with deep breathing B. Reintubation of the trachea C. Intravenous administration of doxapram D. Continuous positive-airway pressure

7. A 120-kg diabetic male is scheduled for emergent pinning of his mandible after a motor vehicle accident. His wife reports that he snores loudly every night with occurrences of breathing cessation. Medical history is also significant for hypertension controlled with a diuretic. On physical examination, he has a large tongue and a wide neck with inadequate mouth opening revealing a Mallampati grade 4 view. His BMI is 38 kg/m2 with a neck circumference of 44 cm .

8. 22. Arterial blood gas (ABG) finding that would confirm Pickwickian syndrome is A. pH = 7.44, PaCO2 = 44, PaO2 = 90, HCO3 = 24 B. pH = 7.35, PaCO2 = 44, PaO2 = 65, HCO3 = 26 C. pH = 7.42, PaCO2 = 36, PaO2 = 80, HCO3 = 22 D. pH = 7.37, PaCO2 = 55, PaO2 = 67, HCO3 = 28

9. 23. The dose of thiopental required for rapid-sequence induction would be increased , as compared with what would be required at his ideal body weight, because of changes in A. Decreased basal metabolic rate B. Increased blood volume C. Increased muscle mass D. Decreased liver metabolism

10. 30. Following a gastric bypass procedure, a 130-kg woman is extubated and breathing spontaneously in the recovery room (PACU). She is breathing at a rate of 24 breaths/min on 10 L/min of oxygen via nasal cannula, and is complaining of continued subjective dyspnea . Arterial blood gas analysis shows PaO2 = 95 mm Hg, PaCO2 = 44 mm Hg, and pH = 7.37. The parameter most closely related to her increased alveolar–arterial oxygen-tension gradient is A. Decreased minute volume B. Decreased functional residual volume C. Decreased expiratory reserve volume D. Decreased respiratory drive

11. Chapter 15 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

12. 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

13. 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

14. Chapter 20 34. A 42-year-old morbidly obese male undergoes a laparoscopic gastric bypass. The surgical procedure lasts 8 hours. Estimated blood loss is 200 mL, and he receives 4.5 L of crystalloid. In the postanesthesia care unit, his urine output is 5 to 10 mL/ hr despite an additional 1 L of crystalloid. The most likely etiology of his oliguria is A. Contrast-induced nephropathy B. Rhabdomyolysis C. Hypovolemia D. Surgical injury of ureters

15. Answers 57. D. Morbidly obese patients with OSA are often subject to persistent hypoxia, which leads to increased pulmonary vascular resistance, eventually leading to pulmonary artery hypertension. Obese patients are also known to have a higher incidence of cardiac problems, including a dilated heart and heart failure. Compression neuropathies are also common in this subpopulation. Dementia is a central-nervous-system–related complication not associated directly with obesity.

16. 96. A. Airway management in obese patients begins first with an adequate physical exam as these patients are more likely to be both more difficult to ventilate and to intubate. The best predictor of difficulty is a short, thick neck ( pretracheal tissue volume) and a history of obstructive sleep apnea .

17. 26. C. Rapid injection of large volumes of local anesthetics either epidurally or intrathecally , especially in short and obese patients can predispose them to higher-than-anticipated levels of neuraxial anesthesia . In this particular situation, the cardiac accelerator fibers were affected, and therefore, the patient experienced bradycardia and hypotension.

18. 2. D. Perioperative morbidity related to obesity is associated with changes in respiratory (e.g., difficult airway, decreased functional residual capacity), cardiovascular (e.g., increased cardiac output), and gastrointestinal (e.g., gastroesophageal reflex disease, increased abdominal pressure) systems that will impact the delivery of anesthesia . Given that metabolism of inhalational agents is increased over normal weight patients, higher minimum alveolar concentrations may be required. Atracurium (including cis-atracurium ) is metabolized via Hofmann degradation and is unaffected by the obese state.

19. 5. A. Postsurgical atelectasis is treated by physiotherapy, focusing on deep breathing while encouraging coughing. An incentive spirometer is often used to promote full expansion of the lungs. Ambulation is also highly encouraged to improve lung inflation. These measures are considered first-line options for his presumed microatelectasis . In the smoker, coughing will also clear the airways of mucous to improve aeration. Doxapram stimulates chemoreceptors in the carotid bodies, which in turn stimulates the respiratory center in the brain stem to increase tidal volume and respiratory rate.

20. 22. D. Obesity hypoventilation syndrome (aka Pickwickian syndrome) is a state in which the severely overweight patient fails to breathe rapidly or deeply enough, resulting in hypoxia and hypercarbia . If Pickwickian syndrome is suspected, the most important initial test is the demonstration of elevated carbon dioxide in the blood. This requires either an ABG or a measurement of bicarbonate levels in venous blood. Expected ABG findings would reveal a chronic, compensated respiratory acidosis .

21. 23. B. Redistribution of thiopental to inactive tissue sites rather than metabolism is the most important determinant of early awakening following a single intravenous injection.

22. 30. C. Dyspnea is a common complaint in individuals with class II or III obesity, especially following a general anesthetic . As such, individuals present with a pronounced reduction in expiratory reserve volume and an increase in the alveolar–arterial oxygen gradient.

23. 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 .

24. 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.

25. 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.

26. 34. B. Rhabdomyolysis is a recognized cause of postoperative renal insufficiency in morbidly obese patients, particularly those who have undergone gastric bypass procedures. Risk factors include the body mass index and duration of surgery. Volume loading, diuretics, and alkalinization of urine to flush the renal tubules can prevent ongoing renal tubular damage and subsequent acute renal failure.