A 4-year-old 15 kg child with chronic recurrent tonsillitis is scheduled for tonsillectomy and adenoidectomy. The mother informs you that the child has a "hole in his heart", that he fatigues easily and is scheduled for a surgical repair following convalescence from this case. He has a loud systolic murmur in the second left intercostal space. Blood pressure is 90/60 mmHg, pulse is 110 bpm, respirations are 24, temperature is 37 degrees centigrade, and hemoglobin is 11.
I. Evaluation of cardiac status
1. Does the history of murmur suggest that additional information is necessary?
2. What is the cardiac diagnosis most likely to be?
3. What additional information would you like to have?
4. Relate the significance of any additional information to anesthesia.
Implications of tonsillitis
1. Why is this case being performed before surgical heart correction?
2. What is your airway management plan?
3. What are the implications of recurrent bouts of tonsillitis?
Selection of premedication
1. Is premedication indicated?
2. Should it be modified in view of this patient's history?
3. What are your drug choices and routes of administration? Explain.
B. Intraoperative course
Choice of anesthesia
1. Which intravenous agents are appropriate for pediatric anesthesia?
Thiopental is most commonly used, with larger doses of 5-6 mg/kg needed. Methohexital can be used, most commonly rectally, and the higher induction dose may lead to unwanted hiccups and musculoskeletal hyperactivity. Propofol is not FDA approved, although it has been used for intravenous induction for 10 years. Ketamine can be useful in children with cardiovascular or airway disease, but is contraindicated in Wolf-Parkinson-White syndrome, as tachycardia produced can lead to unwanted arrhythmias.
1. Which of the available inhalational agents would you choose?
2. Discuss the hemodynamic effects of halothane, enflurane, isoflurane, sevoflurane, and desflurane.
All inhalational agents decrease blood pressure secondary to myocardial depression and vasodilation. Halothane and enflurane primarily decrease myodardial contractility and output, and isoflurane and desflurane decrease systemic vascular resistance.
3. Would you use nitrous oxide? Explain.
4. Give a detailed differential pharmacology of isoflurane vs enflurane, including adult vs pediatric differences, if any.
5. What are the effects of nitrous oxide on cardiac function?
6. What are the effects of an intraventricular septal defect on uptake and speed of induction of inhalational agents?
Selection of anesthetic breathing circuit
1. Would you choose a circle absorber system or a T-piece? Explain.
2. What design of T-piece could you use, and why would it be appropriate?
3. Describe machine flow rates and the principles behind determining an anesthetic system.
Management of fluids
1. You are told that an IV is usually not started for these cases. Do you agree?
2. What is your choice for intravenous fluid?
3. Is physiologic saline a reasonable blood replacement solution? Why or why not?
4. What are some alternate solutions for fluid, if blood products are to be avoided?
Management of failure of the oxygen system
1. The circuit delivery line oxygen alarm sounds, and then the reservoir bag empties. What is your differential diagnosis?
2. How would you establish your diagnosis?
3. What is your management of the patient while establishing the diagnosis?
4. What is the fail-safe system?
C. Postoperative care
Assessment and management of stridor
1. The patient develops a croupy cough and appears cyanotic in the recovery room. What is your differential diagnosis?
2. What is your management?
Management of nausea
1. Unusually severe nausea occurs. What are some causes?
2. Describe drug therapy and explain why you would choose a particular drug.