A 62-year-old 51 kg woman is scheduled for a thyroidectomy and a right radical neck dissection for thyroid carcinoma. She has a long history of heavy smoking and has a chronic, productive cough. She is anxious, thin, coughs frequently, and has coarse ronchi throughout both lung fields. Blood pressure is 132/80 mmHg, pulse is 92 bpm, hematocrit is 52, and room air arterial blood gas shows pH=7.38, paCO2=34 mmHg, paO2=68 mmHg. She has right-axis deviation on electrocardiogram.
I. Pulmonary function
1. How would you assess her pulmonary status?
2. What is the significance of the hematocrit?
3. What is the significance of the arterial blood gas?
4. Would you order pulmonary function tests? Explain.
5. What are your endpoints for surgical preparation?
II. Preoperative airway evaluation
1. Would you anticipate any unusual airway problems? Explain.
2. Would you expect tracheal deviation?
3. Would you expect cord paralysis?
4. Describe the innervation of the larynx.
III. Assessment of thyroid function
1. What are signs of thyrotoxicosis?
2. What is the significance to anesthesia?
3. What are guidelines in therapy?
I. Anesthetic selection
1. Is thiopental contraindicated for induction? Explain.
2. Is halothane preferred? Explain why or why not.
3. What is the effect of inhalation and intravenous agents on bronchomotor tone?
4. What is the effect of chronic obstructive pulmonary disease on anesthetic uptake?
1. Is a V5 lead more appropriate than lead II for monitoring this patient?
2. What are other alternatives?
3. Is a central venous line needed? Why or why not?
4. Compare advantages and disadvantages of left internal jugular vs left subclavian routes.
III. Acute hypotension and bradycardia
1. During neck dissection under halothane/nitrous oxide/oxygen, the blood pressure suddenly drops from 110/70 mmHg to 80/60 mmHg, and the pulse decreases from 72 to 56 bpm. What is your differential diagnosis?
2. How would you manage if this was an air embolus?
IV. Prolonged paralysis
1. Forty-five minutes after the case, consisting of succinylcholine/thiopental induction followed by halothane, she is still not breathing. What is your differential diagnosis?
2. How do you evaluate muscle relaxation at this time?
3. Train-of-four reveals the fourth twitch to be 25% of the first twitch. What is the significance of this?
4. What is your management?
I. Postoperative hypoxemia
1. The patient is on controlled ventilation at an FIO2 of 50%, and arterial blood gas shows pH=7.38, paCO2=39 mmHg, paO2=75 mmHg. Is this acceptable in light of her preoperative values?
2. You do not think this is acceptable. What is your differential diagnosis?
3. What is your treatment?
II. Postoperative respiratory distress
1. During extubation, direct laryngoscopy revealed normal motion of both cords. One hour later, she has evident stridor. What is your differential diagnosis?
The differential diagnosis includes accidental parathyroidectomy, laryngospasm, postextubation croup, expanding hematoma, or soft tissue swelling.
2. What would you do if the right vocal cord was now immobile?
3. Is subglottic edema likely? Why or why not?
4. How is this treated?