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Oral case 41

Created: 5/10/2004

 

A 28-year old gravida 1 para 0 woman with pregnancy-induced hypertension emergently needs cesarean section for late deceleration of the fetal heart rate. She has been treated with hydralazine, hydrochlorothiazide, and magnesium. She is a known narcotic addict on methadone therapy. Blood pressure is 170/100 mm Hg, pulse is 110, respirations are 18, and hemoglobin is 18.

 Preoperative evaluation

I. Pre-eclampsia

1. What is the importance of hypertension to anesthesia?

2. What are the effects of her antihypertensive medications and magnesium on the mother?

3. On the fetus?

4. Why is magnesium effective in this setting?

5. What drugs are teratogenic during the first trimester?

Nitrous oxide and benzodiazepines have been implicated as being teratogenic during the first trimester.

II. Narcotic addiction

1. What are the special considerations in the preoperative evaluation?

2. What are your plans for intraoperative care?

3. Will you use narcotics?

4. Will you use methadone?

III. Fetal distress

1. What is a late deceleration?

2. What is its significance?

3. Are other diagnostic tests indicated preoperatively?

 Intraoperative course

I. Selection of anesthesia

1. Would you give a regional or a general anesthetic? Explain your rationale.

2. The patient has a functioning epidural in place. Would you use it?

3. What local anesthetic would you use in the epidural for a cesarean section?

II. Monitors

1. Do you use special monitors in pre-eclampsia?

2. Do you use special monitors in fetal distress?

3. How does the use of regional anesthesia influence your monitoring decisions?

III. Intraoperative hypertension

1. After rapid sequence induction and intubation, surgeons begin and the blood pressure goes to 240/140 mm Hg. What is the cause?

2. What is the significance to the mother?

3. What is the significance to the fetus?

4. What is your treatment?

5. Discuss intravenous agent versus vapor versus antihypertensive treatment.

IV. Neonatal resuscitation

1. The child is covered with meconium upon delivery, and has a one-minute Apgar of 2. What is your interpretation?

2. What is your plan of action?

3. Describe the major buffering systems.

There are the bicarbonate, phosphate, and protein systems. The fastest one to respond is the bicarbonate system, which is mostly extracellular. Intracellular phosphate and protein systems have about 75% of the total buffering capacity of the body.

4. What is the difference between the chemistry laboratory value of CO2 and the value obtained from the arterial blood gas?

The chemistry value includes total CO2, that from bicarbonate, carbonic acid, and dissolved carbon dioxide. The arterial blood gas value is a calculation from a nomogram of the Henderson-Hasselbalch equation, which uses measured pH and paCO2 values.

3. What determines the paCO2?

The paCO2 equals total body CO2 production divided by alveolar ventilation. Therefore, changes in CO2 production or elimination alter paCO2. Decreased CO2 can be caused by decreased production from hypothermia, or neuromuscular blockade, or increased elimination from hyperventilation, or pulmonary disease that stimulates J-receptors. Increased CO2 can result from increased production due to light anesthesia, hyperthermia, or shivering, or decreased elimination due to hypoventilation, increased dead space from decreased cardiac output, pulmonary embolus, or rebreathing CO2.

3. Would you use bicarbonate?

 Postoperative care

I. Analgesia

1. The patient complains of intense abdominal pain in the recovery room. After general anesthesia was used, what would be your plan of action?

2. If an epidural catheter were still in place, what would you do?

3. How do epidural narcotics work?

4. Would you use epidural narcotics in this patient?

II. Postoperative seizure

1. In the recovery room, she has a grand mal seizure and becomes cyanotic. What is your differential diagnosis?

2. What is your treatment plan?


ArticleDate:20041005
SiteSection: Article
 
   
    
                                            
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