Malignant hyperthermia; sterilization monitoring; sterilization indicators; multipack needle counts

AORN Journal,  Feb, 2007  by Bonnie Denholm

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QUESTION: I work in a freestanding ambulatory surgery center (ASC) that recently scheduled a 10-year-old boy for surgery. The patient was healthy and had not had previous surgeries, but the preoperative interview revealed a strong family history of malignant hyperthermia (MH). The patient's maternal aunt had experienced an MH crisis and the patient's mother had tested positive for MH susceptibility. Consequently, the procedure was cancelled, but I wondered if it was appropriate to have scheduled the procedure in our freestanding ASC in the first place. What are the guidelines for treating MH-susceptible patients in outpatient settings? Are there specific preoperative screening measures that should be done differently in an ASC than in a hospital-based setting?

ANSWER: According to the Malignant Hyperthermia Association of the United States (MHAUS), patients who are MH susceptible can be scheduled for surgery in outpatient settings if the anesthesia care provider uses a trigger-free anesthetic technique. (1) An example of a trigger-free anesthetic technique is one that includes propofol, opioids, or non-depolarizing muscle relaxants (eg, pancuronium) and does not include halothane or isoflurane as an inhalation agent. Nitrous oxide is safe for use as an inhaled general anesthetic, and local anesthetics (eg, lidocaine, procaine) also are safe. (2,3) When MH-susceptible patients undergo uneventful general anesthetics in ASCs, they should be monitored for at least 60 minutes in the phase I postanesthesia care unit (PACU) and at least 90 minutes in the phase 2 PACU or step-down unit before being discharged. (1,4,5)

Facility preparedness. Every patient should be considered potentially at risk for developing MH no matter where the patient is scheduled to have surgery. Previous uneventful anesthesia does not eliminate the possibility of MH, because patients may undergo multiple episodes of anesthesia before MH is triggered. (6) Personnel working in any location that administers general anesthetics and/or succinylcholine should be prepared to manage an MH crisis. (3) Preparations include stocking a supply of 36 vials of dantrolene sodium and sterile water, having access to ice, and ensuring availability of the pharmacologic agents and equipment listed in Table 1.

Staff member education. Every facility should include MH training in the orientation plan for new members of the perioperative team and other personnel who will be involved in responding to the crisis. Ongoing periodic reviews also should be scheduled. The MHAUS recommendations suggest that the perioperative team initiate mock MH drills at least twice a year to improve staff member efficiency in treating a patient during an MH crisis. (7)

Dantrolene sodium is difficult to mix, so some institutions reconstitute the outdated medication during staff member education sessions to give hands-on training during the mock drills. Perioperative nurses also may benefit from a review of the electrolyte imbalances and arterial blood gas shifts that occur with respiratory and metabolic acidosis during an MH crisis. Facilities should identify specific tasks assigned to each member of the response team to ensure effective management of an MH crisis. Procedure manuals are available from the MHAUS to assist in assigning specific tasks and to facilitate staff member education. (7)

Signs and symptoms of malignant hyperthermia. Malignant hyperthermia may present with a variety of signs and symptoms during an acute phase or may develop over a course of several hours and present in a subtler fashion. Unexplained tachycardia is often the first sign of an acute MH episode. Jaw muscle rigidity that is severe, sustained, or interferes with intubation should be considered a possible sign of an impending MH crisis.

Guidelines for MH susceptibility. Patients identified as MH susceptible who are undergoing surgery in an ASC and exhibit mild spasms in their jaw or masseter muscle rigidity should not be discharged without further observation. The following guidelines should be used if suspicious symptoms are noted.

* The patient should be observed for at least 10 hours if he or she has demonstrated mild symptoms of jaw tension but no increase in creatine kinase and no signs of myoglobinuria, muscle weakness, muscle soreness, hyperthermia, or abnormal electrolytes. The patient may be discharged after 10 to 12 hours with instructions to return to an emergency room at the first sign of elevated temperature. (3)

* The patient should be observed overnight if the patient has dark or cola-colored urine, increased temperature or pulse rate, or changes in acid-base balance.

* If the patient had severe jaw rigidity but no other symptoms, the patient should be observed overnight to ensure that there is no progression of symptoms and to decrease the risk of an MH crisis. (3-5)

Malignant hyperthermia occurs most frequently during administration of anesthesia. Initial symptoms generally are not seen in the PACU, especially after more than two hours have elapsed since the anesthetic agents were discontinued. (8) When patients present with symptoms of a fever in the PACU, it generally is due to sepsis or iatrogenic heating and is not related to MH. Temperature increases after a patient is discharged generally are not related to MH unless there were signs of MH (eg, myoglobinuria, muscle weakness, muscle rigidity) before discharge. (3)