356 Obstetrics and Gynecology Board Review •••
❍ Why is sinus tachycardia to be avoided in postoperative patients with aortic stenosis?
Decrease in ventricular filling in diastole exacerbating inadequate cardiac output.
❍ What is the most important aspect in diagnosing myocardial infarction in the postoperative patient?
A high degree of suspicion, since only 50% of postsurgical patients have chest pain.
❍ What is the most sensitive indicator of postoperative myocardial infarction?
The creatinine phosphokinase MB isoenzyme level.
❍ In patients with coronary artery disease, what constitutes significant hypotension, and puts the patient at
risk of myocardial infarction?
Decrease in systolic blood pressure of 33% to 50% for at least 10 minutes.
❍ What should be the management of patients who have been on beta-blockers in the intraoperative and
postoperative period?
Continuing these agents, since removal can lead to severe rebound with hypertension and angina.
❍ What precautions should be taken with patients with pacemakers?
Electrocautery devices can trigger demand type pacemakers. Therefore, the electrode should be placed as far from
the pacemaker as possible. Also, a magnet should be used to convert the pacemaker from the demand to a fixed
pacing mode.
❍ How does intermittent positive pressure breathing (IPPB) therapy compare with incentive spirometry in the
prevention of atelectasis in high-risk patients?
Incentive spirometry is as effective, is cheaper, and has less complications.
❍ What glucose value is targeted in the postoperative diabetic patient?
<180 to 240 mg/dL to prevent glucosuria, dehydration, and leukocyte inhibition.
❍ What are the indications of mechanical ventilation in the postoperative patient?
Acute respiratory acidosis, ARDS, and progressive symptomatic hypoxemia unresponsive to oxygen
supplementation.
❍ What is the difference between assist-control (AC) and intermittent mechanical ventilation (IMV)?
With AC, the ventilator will provide assistance to any inspiration initiated by the patient; if necessary provide
additional breaths so that the total number of breaths per minute meets the designated set rate. IMV provides only
a set number of assisted ventilations and does not provide assistance to breaths initiated by the patient. IMV is
useful in patients who hyperventilate or those being weaned from the ventilatory support.
❍ What is the most common renal problem in the postoperative patient?
Oliguria as defined as <25 mL/hour urine output.