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Oral case 92

Created: 4/11/2004

A 57-year old 100 kg man is scheduled for mediastinoscopy for biopsy of a mediastinal mass thought to be lymphoma. Chest radiograph shows that the trachea is deviated to the left, secondary to the mass. He has a history of hypertension and supraventricular tachycardia, and he is on digoxin 0.25 mg and hydrochlorothiazide 50 mg per day. Blood pressure is 130/70 mm Hg, pulse is 66 bpm, respirations are 18, oral temperature is 37.2 degrees centigrade, hemoglobin is 16 gm/dl, and potassium is 3.3 mEq/l.

 Preoperative Evaluation

I. Assessment of breathing

1. Which pulmonary function tests, if any, will be helpful? Explain why.

2. What may his flow-volume loop show?

3. Does he need a preoperative bronchoscopy? Why or why not?

4. Would you want other studies? Explain your rationale.

II. Significance of tachycardia

1. Is a further cardiac workup indicated?

2. What would you want to know? Explain.

3. What is the significance of the potassium value?

4. Should surgery be postponed until the potassium is replaced?

 Intraoperative Course

I. Anesthesia airway management

1. Do you want an awake intubation or will you anesthetize the patient?

There is a serious question of whether the patient will be able to be ventilated and intubated once anesthetized and paralyzed. Consideration of awake intubation is warranted.

2. What patients are not good candidates for awake intubation?

Those with a history of difficult intubation, with an airway problem like a soft-tissue infection or a hematoma of the neck, mandibular fractures, facial deformities, morbid obesity, and cancer or radiation therapy to the neck or larynx.

2. Would you use direct laryngoscopy or a fiberoptic?

An attempt at gentle awake laryngoscopy with fiberoptic intubation as a backup plan is reasonable. After discussion with the patient, the operating room

3. How would you prepare for each?

After discussion with the patient, the operating room is prepared with topical local anesthetics, intravenous sedatives, oral, nasal, and endotracheal tubes, oxygen, suction, and a functioning fiberoptic endoscope. A surgeon should be at the bedside to perform a surgical airway if necessary. Premedication includes glycopyrrolate and nebulized lidocaine. Standard monitors are applied when the patient arrives, and supplemental oxygen is given. Sedation is carefully titrated so as not to loose protective reflexes, or cause desaturation. A vasoconstrictor like cocaine or phenylephrine is applied to the nares, and a transtracheal, glossopharyngeal and/or superior laryngeal nerve block is performed. Anesthetic spray is applied to the tongue, posterior pharynx, and hypopharynx, and then gentle laryngoscopy is attempted.

4. Are nerve blocks useful for awake intubations?

The biggest risk is having the patient lose protective airway reflexes. If both the superior laryngeal nerve, which provides sensory innervation above the vocal cords, and a transtracheal block are performed, and the patient has a full stomach, all reflexes are essentially lost.

4. He develops stridor and becomes cyanotic upon unsuccessful intubation attempt. What do you do now?

Call for help. In the interim, with the endotracheal tube on the fiberoptic endoscope, it is lowered from the nare into the posterior pharynx, until tracheal rings and carina are visualized. Then the endotracheal tube is passed into the trachea, with confirmation of placement done by verifying breath sounds and end-tidal CO2. If unsuccessful, the surgeon should secure a surgical airway.

II. Maintenance

1. Blood pressure is 180/100 mmHg after intubation. How will you proceed?

2. Is oxygen plus halothane and a succinylcholine infusion acceptable? Explain why or why not.

3. What is your preferred technique? Give reasons.

4. Would you monitor neuromuscular function? Why or why not?

III. Management of injury to the pulmonary artery

1. After the third biopsy retrieval, the mediastinoscope fills with blood. What are possible sites of hemorrhage?

2. What are the consequences of hemorrhage?

3. What is your management for the sternal split?

4. Resistance to breathing increases noticeably. What is the significance of this?

5. What is your management?

V. Management of blood loss

1. You have given four units of packed red blood cells, and the bleeding is still not controlled. What further blood products will you give? Explain.

2. Discuss crystalloid management in this setting.

3. Do you need more monitors?

4. Which other monitors would you want? Explain why.

5. The central venous pressure is 14 mmHg. What is your interpretation?

6. Do you want other data?

7. What other data do you want? Explain your rationale.

 Postoperative Care

I. Anesthesia for reoperation

1. The chest tube drainage immediately postoperatively is 500 ml/hr for two hours. Re-exploration is required. What are your drug choices for urgent surgery?

2. What type of endotracheal tube would you want? Give reasons.

II. Management of pain

1. Would patient-controlled analgesia be a reasonable choice? Explain.

2. What are your drug choices? Explain your rationale.

3. Could an epidural be used for pain control after a thoracic procedure?

4. Discuss pros and cons of narcotics vs local anesthetics for continuous epidural.

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