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Topic: Appendectomy - fever, tachycardia, hypertension
A 24-year-old male has had nausea, anorexia, and abdominal pain for the last 18 hours. His temperature is 38.7° C. pulse 105/minute BP 115/70. The patient feels cold. His right lower quadrant is tender to palpation. WBC 13000. He is scheduled for an exploratory laparotomy. He is given 1gram cefazolin in the emergency department. He is induced with propofol, 150 mg fentanyl, and rocuronium. He is maintained with sevoflurane and nitrous oxide. After induction, HR 85/minute. He becomes progressively tachycardic to HR 130/minute. BP 150/85.
1) Which of the following might explain his tachycardia?
A) fever
B) hypovolemia
C) light anesthesia
D) malignant hyperthermia
E) fentanyl-induced histamine release
End-tidal CO2 42 mm with tidal volume 700 cc and rate 8/minute. An inflamed appendix with surrounding fibrinopurulent material is excised. During skin closure, the patient’s neuromuscular blockade is reversed with neostigmine 2.5 mg and glycopyrrolate 0.5 mg. The patient is extubated when responsive. HR is now 140/minute, BP 160/90 T 39° C. respiratory rate 24/minute.
2) Which of the following might explain the tachycardia and hypertension?
A) pain
B) residual paralysis with inadequate ventilation
C) fever
D) pheochromocytoma
The patient is given 10 mg IV hydralazine and 5 mg IV metoprolol. HR 135/minute, BP 130/85 T 39.3° C. His skin appears mottled. ABG is obtained: PaO2 175 PaCO2 47 pH 7.28
3) The mild respiratory acidosis is due to:
A) Hypoventilation with normal carbon dioxide production
B) increased carbon dioxide production
C) cannot know without measuring minute ventilation
Dantrolene 180 mg IV is given. HR 120/minute, BP 135/85 T 38.3° C. respiratory rate 20/minute. K+ 4.5 mEq/l WBC 16,000. Urine dipstick is negative for heme. The patient is admitted to an ICU and treated with dantrolene 70 mg iv q6 hours. T 37.8 – 38.3° C. overnight. CK 340 U/liter 12 hours postoperatively. 28 hours postoperatively, the patient’s temperature spikes to 39.2° C. with shaking chills.
4) The temperature spike and shaking chills are least likely caused by:
A) Atelectasis
B) Bacteremia from appendicitis
C) Recrudescent malignant hyperthermia
Blood cultures obtained demonstrated E.coli in 2/4 bottles.
The patient’s anesthesiologist insists that bacteremia alone could not explain the signs noted upon emergence from anesthesia. The patient has many siblings.
5) How would you best counsel the patient?
A) Obtain medical ID tag warning of MH susceptibility.
B) Refer to MH diagnostic center for caffeine-halothane contracture testing.
C) Refer the patient for testing for a ryanodine receptor mutation; if no MH-associated mutation found, this excludes MH susceptibility.
Answers:
1. A, B, C, D (Fentanyl does not cause significant histamine release.)
2. A, B, C (Regarding D, one would likely see a higher blood pressure with a
norepinephrine secreting pheochromocytoma.)
3. C (One cannot attribute hypercarbia to increased carbon dioxide
production, i.e., hypermetabolism without measuring minute ventilation.)
4. C
5. B
Narrative:
This patient presented with typical findings of acute appendicitis that was confirmed during surgery. During emergence the patient’s temperature started to increase, with tachycardia, mild hypertension, and mottling. Treatment with hydralazine may have further increased his heart rate. The patient’s infection is sufficient to explain his postoperative course, although an MH-susceptible patient could have acute appendicitis and have an acute MH crisis. Arguing against a simultaneous MH episode are the lack of significant skeletal muscle injury and the demonstration of E. coli bacteremia during a temperature spike more than 24 hours postoperatively.
The MH consultant was unsuccessful in persuading the patient’s anesthesiologist that infection alone accounted for the signs observed during emergence from anesthesia. The consultant strongly opposed labeling the patient as MH susceptible without undergoing muscle biopsy for contracture testing at a diagnostic center. Not only might the patient be labeled with an incorrect diagnosis, but all of his siblings would also be labeled MH susceptible. The consultant did not recommend testing for an MH-associated ryanodine receptor mutation because of the low likelihood that this was an MH episode. Less than 50% of patients with a well-documented MH episode have a described ryanodine receptor mutation. While finding a causal mutation can confirm MH susceptibility, absence of a mutation cannot rule out MH susceptibility.
This patient underwent muscle biopsy at an MH diagnostic center. His muscle strips reacted normally to both halothane and caffeine, effectively ruling out MH susceptibility.
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MH Hotline Consultant
Professor of Anesthesiology
UCLA School of Medicine
Los Angeles CA 90095-1778
