May 2006 Case of the Month

MH Hotline
800MH-HYPER or 800-644-9737
available 24/7
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Topic: Lithotripsy - postop fever, shivering, DIC

A 56-year-old 60-kg female underwent cystoscopy with removal of ureteral stones between 0930 - 1130 today. She was induced with propofol and relaxed with succinylcholine before endotracheal intubation. GA was maintained with sevoflurane with supplemental fentanyl. Intraoperative end-tidal CO₂ ranged between 35-38 mm. No elevation of temperature was noted during the procedure. Demerol 12.5 mg iv X 3 was given for shivering in the PACU. Temperature was 102° F at 1330. Noted increased tone and temperature up to 105.8° F by 1405. Re-intubated using propofol. Given 720 mg intravenous dantrolene between 1415 - 1515 for treatment of presumed MH. Also aggressively cooled down to 35.6° C and given rocuronium at 1445. Received Ancef in OR. Blood cultures performed. The caller, who was not the anesthesia professional for the procedure, had questions regarding the diagnosis of MH and recommendations for continued therapy.

1) Which specific laboratory test result would you like to know prior to initiating dantrolene therapy?

A) Plasma potassium level

B) Presence of urine myoglobin

C) Arterial or venous blood gas

D) CK level

In review of the data, an ABG had been obtained prior to re-intubation and starting dantrolene. With F_IO₂ 0.4, PaO₂ 88, PaCO₂ 32 pH 7.43.

2) Given the associated temperature of 105.8° F, this ABG result excludes the diagnosis of anesthetic-induced malignant hyperthermia.

A) True

B) False

The platelet count was 90,000 with PT 15 seconds and PTT 52 seconds.

3) Which of the following statements is correct:

A) Thrombocytopenia and abnormal coags are unique to sepsis.

B) Thrombocytopenia and abnormal coags cannot complicate the course of MH.

C) Thrombocytopenia and abnormal coags can complicate sepsis or severe rhabdomyolysis.

Plasma potassium was 3.0 mEq/liter, CK 150, and the WBC was 2,100 with 30% bands.

4) The diagnosis that best explains the patient’s post-anesthetic course is:

A) Drug fever

B) Urosepsis

C) Anesthetic-induced MH

D) Neuroleptic Malignant Syndrome

Answers:

1. C

2. A

3. C

4. B

Narrative:

This patient underwent cystoscopy and removal of ureteral stones. Fever with or without evidence of sepsis is a well-described sequela of this procedure. In retrospect, the prominent shivering was a response to a raised thermoregulatory setpoint caused by inflammatory cytokines. Blood gas results are highly desirable when attempting to distinguish anesthetic-induced MH from other causes of hyperthermia. This patient had a strikingly benign ABG associated with marked temperature elevation, effectively excluding the diagnosis of MH. On the other hand, one could see metabolic and respiratory acidosis due to sepsis or MH, making it difficult (or impossible) to exclude an acute MH episode. If acute MH cannot be confidently excluded, one should promptly initiate dantrolene therapy. Plasma potassium and CK level may both be normal early in the course of acute MH. The patient will have some degree of hematuria following the procedure, rendering presence of heme+ pigment on dipstick non-specific for detection of myoglobinuria. Specific determination of presence or absence of myoglobinuria will not be immediately available in this setting. There is no evidence that dantrolene therapy is intrinsically harmful in the septic patient. It is possible that focusing on MH to the exclusion of other causes of postoperative fever may result in delayed diagnosis or treatment of conditions, e.g. gram-negative bacterial sepsis.

Thrombocytopenia with elevated PT and PTT can be seen with any disorder that can be complicated by disseminated intravascular coagulation (DIC), including sepsis, severe pre-eclampsia, exertional heat stroke, MH, and other causes of severe rhabdomyolysis.
The constellation of hyperthermia, thrombocytopenia with elevated coags, and leucopenia with left shift is best explained by urosepsis in this patient.

The consultant and the caller agreed that the patient had sepsis, and no additional dantrolene was ordered. The patient subsequently became hypotensive, with a brief episode of pulseless electrical activity that was promptly treated with epinephrine. The patient was placed on dobutamine to improve cardiac output, the WBC increased to 30,000, and urine cultures demonstrated E. coli.

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Harvey K. Rosenbaum, MD
MH Hotline Consultant
Professor of Anesthesiology
UCLA School of Medicine
Los Angeles CA 90095-1778