A 24-year old 59 kg female who is 19 weeks pregnant presents for emergency appendectomy after 36 hours of intense abdominal pain and vomiting. She has a long history of diabetes mellitus and normally takes NPH insulin 35 U every morning, and regular insulin 5 U every morning and evening. She has not eaten in 24 hours. Blood pressure is 100/80 mm Hg, pulse is 115, respirations are 22, and temperature is 38.5 degrees centigrade. Urine ketones are 2+, and hemoglobin is 14.
I. Volume and metabolic status
1. Is the patient volume significantly depleted?
2. What mechanisms would be involved?
3. Do you want other lab tests?
4. Sodium is 135, potassium is 5.1, chloride is 85, bicarbonate is 19, and glucose is 410 mg/dl. What is your interpretation?
5. How would you manage volume replacement?
6. How would you manage preoperative insulin therapy?
II. Anesthesia and pregnancy
1. She is concerned about the effect of anesthesia on premature labor, and on birth defects. What is your response?
I. Choice of anesthesia
1. The patient desires to be awake for the case. What is your response?
2. Compare and contrast regional versus general anesthesia.
3. Compare and contrast spinal versus epidural anesthesia.
4. Will you sedate prior to the procedure?
1. How will you monitor her diabetic status intraoperatively?
2. How "tightly" should her glucose be controlled?
3. Is a Foley catheter indicated?
IV. Management of intraoperative hypotension
1. Three minutes after administration of 8 mg tetracaine into the subarachnoid space, the blood pressure falls to 60/45 mm Hg. What is your differential diagnosis?
2. What is your management?
V. Intraoperative dysphoria
1. During skin closure, she is combative and dysphoric. What is your differential diagnosis?
2. What is the mechanism of this dysphoria?
I. Postoperative hypoxia
1. In the recovery room, she looks dusky. Pulse oximeter reads 85% saturation on room air, and chest radiogram shows bilateral lower lobe infiltrates. What if your differential diagnosis?
2. What is your treatment?
3. What are indications for intubation?
Operative indications include the prevention of aspiration, surgical procedures of the chest, abdomen, or cranium, or of the head and neck that disallow manual airway support. Other indications include procedures that require nonsupine positions that require control of intracranial hypertension, protection of a healthy lung from a contaminated lung, and the need to provide positive pressure ventilation. Nonoperative indications include protection of the airway for altered mental status, bronchial tree toilet, and severe injury associated with respiratory failure, such as sepsis, hypoxemia, or hypercarbia.
4. What are indications for ventilation?
5. What are the ventilatory effects of inhalational anesthetics?
They depress ventilation directly through medullary centers, and indirectly through altering intercostal muscle function. Tidal volume decreases, therefore minute ventilation decreases, and respiratory rate increases. At lower than one MAC, the ventilatory response to hypoxia is abolished, and the ventilatory response to hypercarbia is decreased by increasing MAC.
6. What are the ventilatory effects of narcotics?
They shift the carbon dioxide response curve to the right, so that increased carbon dioxide levels are necessary in order to stimulate respiration.
6. What are the effects of volatile anesthetics on hypoxic pulmonary vasoconstriction?
When alveolar oxygen in decreased, the pulmonary vasculature constricts, matching ventilation with perfusion. Inhalational gases inhibit this response.
5. What factors decrease mucociliary clearance in the bronchial tree?
Dry inhalational anesthetics, positive pressure ventilation, and high-inspired oxygen content contribute to ciliary impairment.
5. What are indications for positive end-expiratory pressure?
6. What are indications for continuous positive airway pressure?
II. Postoperative neurologic syndrome
1. On the first postoperative day, she complains of violent headache when upright, double vision, and paresthesias going down the lateral aspect of her right thigh. What is your response?