ORAL EXAM, Tuesday, May 8 #3

RESIDENTS AND FACULTY: This is a type A stem. Preoperative topics are NOT discussed. The exam begins with the arrival of the patient in the operating room.

A 38-year-old, 100 Kg, 5'5" tall woman is brought to the operating room for drainage of a subhepatic abscess.

HPI: The patient underwent a laparoscopic cholecystectomy for cholecystitis and cholelithiasis four days ago. Subsequently she developed fever, leucocytosis, abdominal pain and tenderness, and was hospitalized 48 hours ago. Abdominal CT showed a large right subhepatic collection that could not be adequately drained by interventional radiology. She is receiving antibiotics (gentamycin, piperacillin) and intramuscular morphine for pain. She has been NPO since admission and is receiving D5 1I2NS through a 20 gauge peripheral IV catheter.

PMH: She has juvenile onset (Type I) diabetes mellitus since age 8, complicated by renal insufficiency for the past 18 months. BUN and creatinine have been stable for 6 months at 54 and 2.8 mg/dl respectively. Since hospitalized 48 hours ago, urine output has averaged 500 ml per 8-hour shift. Her medications prior to admission have been insulin - NPH 30 units in AM and 10 units in PM; regular 15 units in AM and 20 units in PM. Since admission she has been receiving regular insulin by sliding scale, and received 5 units IV 2 hours ago for a serum glucose of 280 mg/dl. She has no allergies and does not smoke or use illicit drugs.

PHYS EXAM: P 104, BP 137/75, R 26, T 38C.

She is awake, alert and well oriented. Her airway is a class III, with poor visualization of posterior pharynx, a large tongue and prominent upper incisors but good neck mobility and mouth opening. Chest auscultation reveals bi-basilar crackling rales. Cardiac exam is normal. Abdominal exam reveals diffuse tenderness. She has no peripheral edema.

Chest XRAY: Mild right basilar atelectasis.

LABS: Hgb 11 gms/dl, WBC 18,000, Na 134 meq/L, K 5.6 meq/L,

Cl 95 meq/L, C02 20 meq/L, BUN 68 mg/dl, Creatinine 3.2 mg/dl, glucose 160 mg/dl.

Her anesthesiologist from previous surgery is unavailable to provide anesthesia, but records indicate a difficult intubation with 3 attempts using a #4 miller blade. He was only able to visualize posterior arytenoids. The remainder of the 2-hour anesthetic was uneventful.

ORAL EXAM, Tuesday, May 8 #3

FACULTY: This is a type A stem. Preoperative topics are NOT discussed. The exam begins with the arrival of the patient in the operating room. Please allow 5 minutes for feedback at the end.

A. INTRA-OPERATIVE MANAGEMENT - 10 Minutes

1. Anesthetic Choice: Your colleague, who provided general anesthesia previously, recommends regional anesthesia because of airway difficulties. Agree? Why/why not? Spinal? Epidural? Would you feel the same if she weighed 55 Kg? Why/why not?

2. Induction: Is a rapid sequence induction appropriate? Why/why not? If yes, would ketamine be preferable to thiopental? Etomidate? Propofol? Why for each? If not, how would you secure the airway prior to induction? Would fiberoptic laryngoscopy be preferable to blind nasal intubation? Why/why not? Would sedation with midazolam and fentanyl be appropriate prior to awake intubation? If not, how would you achieve patient comfort? Rationale.

3. Ventilation: Peak airway pressures are 50 mmHg shortly after intubation. Could obesity cause this? Other causes? How evaluate? How would you differentiate restrictive problem due to obesity vs. aspiration? Versus endobronchial intubation? Versus bronchospasm? Most likely Dx here? How manage? Rationale.

B. POST-OPERATIVE CARE - 10 Minutes

I. Hypoxemia: You transport her to ICU intubated and she is mechanically ventilated with IMV of 6. Gradual hypoxemia ensues over 5 hours, with Sp02 =89%. DDx? Could obesity be underlying cause? How manage? CPAP vs controlled ventilation? Which? Why?

2. Pneumonia: Problem persists and purulent sputum is noted in the tracheal tube. Temperature is 103°F. DDx? Pneumonia suspected. How confirm? Gram positive cocci in sputum. Rx?

3. Extubation: Problem clears. What will be your criteria for extubation? Same for all patients? Altered by obesity? By diabetes? By renal disease? When criteria are met, how will you wean from ventilation? Is a trial by T-piece necessary? Why/why not?

4. Oliguria: Urine output decreases to 120 ml over the past 8 hours. BUN =84, Creatinine = 7.2. DDx? Manage? Furosemide vs. fluids vs. dopamine? What if creatinine 3.8? How determine pre-renal from renal causes? Is it important to differentiate? Why? What indications would you consider to determine need for dialysis? Why?

C. ADDITIONAL TOPICS - 5 Minutes

1. (CA-1, 2, or 3) Tamponade: A 38-year-old woman is brought to OR for pericardial window and possible pericardectomy to treat a malignancy-induced tamponade. BP 85/55, P 98, CVP 22. Discuss your assessment of patient prior to anesthesia. Assuming pericardiocentesis unsuccessful and patient receiving dopamine at 8 meg/kg/min, how would you induce anesthesia? What are likely causes of hypotension during anesthetic induction? Should the trachea be intubated? Why/why not? Would laryngeal mask airway suffice? Why/why not? Should spontaneous ventilation be maintained?

Why/why not?

2. (CA-2 or 3) Acute pain: You are consulted to provide pain relief for a 78-year-old man who fell and broke 4 ribs. He is now splinting his chest and not coughing while in the ICU. He has stable angina for which he takes atenolol and nitropaste daily. The surgeons request an epidural catheter. Is this reasonable? Advantages/disadvantages over PCA? Over intrapleural analgesia? Advantages/disadvantages of lumbar vs. thoracic catheter? What opioid? Why?