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Oral case 31

Created: 4/10/2004

A 23-year old 70 kg man requires open reduction and fixation of femoral, mandibular and maxillary fractures resulting from falling out of a second-story building during an alcoholic spree. He is incoherent, combative, and will not open his mouth. A friend reports that he is an insulin-dependent diabetic and also takes an antidepressant drug. Blood pressure is 90/60 mm Hg, pulse is 120 bpm, respirations are 24, temperature is 37 degrees centigrade, hematocrit is 40%, glucose is 230 mg/dL, and SGOT is 80.

 Preoperative evaluation

I. Trauma

1. What other injuries should be considered from your perspective?

2. What are the studies required before proceeding with general anesthesia?

3. A chest radiogram shows a 10% pneumothorax. Should a chest tube be inserted preoperatively? Explain.

II. Metabolic status

1. Do you need further lab studies concerning the diabetes mellitus? Which ones?

2. Serum ketones are 3+. What is your interpretation?

3. How would you manage this?

4. What are the effects of acute alcoholic intoxication?

5. Chronic alcoholism?

6. Do you want additional liver function tests? Explain.

7. How does vitamin K deficiency affect clotting factors and coagulation?

The liver synthesizes factors II, VII, IX and X, with the vitamin-K enzymatic reaction enabling the factors to bind to the phospholipid surface through calcium. Factor VII, found only in the extrinsic pathway, is first affected. Further deficiency affects both pathways.

7. How will the results of liver function tests affect you management?

Coagulation abnormalities are treated with subcutaneous vitamin K, which reverses deficiency of liver-dependent factors in six to twenty-four hours. In emergency situations, fresh frozen plasma may be given.

III. Airway evaluation

1. How can you examine the airway without opening the patient's mouth?

2. Are radiographs helpful? What would you be looking for?

3. Would you recommend tracheostomy rather than attempt intubation? Why or why not?

4. If a cervical spine fracture has not been ruled out, does this alter your plan?

 Intraoperative course

I. Monitoring

1. What monitoring is essential in a combative patient before sedation or anesthesia?

2. How do you assess fluid balance in this patient?

3. Would you require a central venous catheter? Explain.

4. Explain the anion gap.

The anion gap is used to evaluate acid/base disorders, and is calculated by subtracting the chloride and bicarbonate ion concentrations from the sodium concentration. A normal gap is between 8 and 12. An increased gap usually means that bicarbonate is being used to titrate excess acid, and usually reflects a metabolic acidosis.

5. What is your differential diagnosis of anion gap metabolic acidosis?

The presence of acid can be from diabetic ketoacidosis, alcoholic ketoacidosis, starvation ketoacidosis, lactate acidosis from hypovolemia, hypotension, hypoxia, toxins, or enzyme defects, toxins such as salicylates, paraldehyde, methanol, or ethylene glycol, hyperosmolar hyperosmotic nonketotic coma, and uremic acidosis from renal failure.

6. What is your differential diagnosis of non-anion gap metabolic acidosis?

Loss of bicarbonate can be from diarrhea, renal tubular acidosis, ureteral diversion, interstitial nephritis, ureteral obstruction, and from drugs like spironolactone and acetazolamide.

4. Would you require a Foley catheter in a diabetic with ketoacidosis? Explain.

II. Airway management

1. Assume no respiratory distress. Is an awake, blind nasotracheal intubation appropriate?

2. The patient remains combative. How would you proceed?

3. Is ketamine an appropriate choice for induction? Explain.

4. What is the effect on airway reflexes?

5. What if the patient becomes apneic?

III. Anesthetic choices

1. Does abnormal liver function influence your choice of maintenance agents? Explain.

2. What will you use?

3. What are the effects on hepatic perfusion, oxygenation, and function?

4. What are the effects of abnormal hepatic function on anesthetic recovery?

5. On dosage of muscle relaxants?

IV. Diabetic management

1. How do you determine if insulin is required intraoperatively?

2. Is it satisfactory to monitor urine glucose and ketones? Why or why not?

3. If the serum glucose is 700 mg/dl, what dangers is the patient in?

4. What treatment would you give?

 Postoperative care

I. Extubation

1. How do you proceed if the mouth is wired shut?

2. What are your criteria for safe extubation?

3. Do you have any modifications for a delirious patient?

4. How would you assess protective airway reflexes?

5. How do you plan to manage secretions?

II. Hypothermia

1. Axillary temperature is 32 degrees centigrade. What are the major risks?

2. The patient begins to shiver. What dangers do this pose?

3. Would you treat this? If so, how?

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