PATIENT SAFETY Outcomes Article Evidence-Based Patient Safety Advisory: Malignant Hyperthermia Raffi Gurunluoglu, M.D., Summary: As more and more routine plastic surgery procedures move from the Ph.D. hospital to outpatient surgery facilities, plastic surgeons must be aware of the risk Jennifer A. Swanson, B.S., factors for life-threatening events that might occur in this setting. This awareness M.Ed. includes recognition of the signs and symptoms and the management of a rare Phillip C. Haeck, M.D. but life-threatening condition, malignant hyperthermia. This article reviews the and the ASPS Patient Safety current understanding of the concepts pertinent to malignant hyperthermia Committee diagnosis and treatment in the outpatient setting and current standards and Denver, Colo.; and Arlington Heights, Ill. recommendations for physicians and support personnel regarding malignant hyperthermia preparedness in office-based surgery and anesthesia. (Plast. Re- constr. Surg. 124 (Suppl.): 68S, 2009.) s more and more routine plastic surgery information and improvements in medication, procedures move from the hospital to out- successful treatment has become the norm rather Apatient surgery facilities, plastic surgeons than the exception. The incidence of malignant must be aware of the signs and symptoms and the hyperthermia episodes during anesthesia is management of a rare life-threatening condition, thought to be between one in 5000 and one in malignant hyperthermia. Although the abrupt, 50,000 to 100,000 anesthetic encounters, but be- unpredicted death of a healthy individual under- cause of accurate diagnosis, timely recognition, going surgery in any setting is extremely unusual, and appropriate treatment, mortality rates have when it occurs in an outpatient facility, it will al- fallen from 70 percent when the first cases came ways be questioned whether this person should to light to less than 5 percent over 30 years later. have had their procedure performed instead as an This article reviews the current concepts per- inpatient. It is imperative then that all surgeons tinent to malignant hyperthermia in the outpa- using general anesthesia understand what malig- tient setting, with particular emphasis on presur- nant hyperthermia risks are for their patients, and gical evaluation, identification of susceptible what to do if confronted by it. individuals and selection of the appropriate set- Malignant hyperthermia is an inherited my- ting for these patients, appropriate anesthetic opathy that presents as a hypermetabolic reaction agents for susceptible patients, early diagnosis and to potent volatile anesthetic gases, such as halo- management of acute malignant hyperthermia, and thane, enflurane, isoflurane, sevoflurane, and des- postoperative vigilance and care. Also discussed are flurane, and the depolarizing muscle relaxant current standards/guidelines and recommenda- succinylcholine. Critical worldwide insight into tions for physicians and support personnel re- malignant hyperthermia began in 1960, when garding facility and equipment requirements and Denborough and Lovell described a series of an- malignant hyperthermia preparedness in office- esthetic deaths in a family.1 Since that time, aware- based surgery and anesthesia. ness of malignant hyperthermia has reached crit- This patient safety advisory was developed ical mass where, through widely disseminated through a comprehensive review of the scientific literature and a consensus of the Patient Safety From the Denver Health Medical Center and the American Committee. The supporting literature was criti- Society of Plastic Surgeons’ Patient Safety Committee. cally appraised for study quality according to cri- Received for publication March 3, 2009; accepted May 27, teria referenced in key publications on evidence- 2009. Approved by the ASPS Executive Committee, January 10, 2009. The members of the ASPS Patient Safety Committee are listed Disclosure: The authors have no commercial asso- at the end of this article. ciations that might pose or create a conflict of inter- Copyright ©2009 by the American Society of Plastic Surgeons est with the information presented in this article. DOI: 10.1097/PRS.0b013e3181b54626 68S www.PRSJournal.com Volume 124, Number 4S • Malignant Hyperthermia based medicine.2–6 Depending on study design of medical care are determined on the basis of all and quality, each reference was assigned a corre- the facts or circumstances involved in an individ- sponding level of evidence (I through V) with the ual case and are subject to change as scientific American Society of Plastic Surgeons (ASPS) Ev- knowledge and technology advance, and as prac- idence Rating Scales (Table 1),7 and the evidence tice patterns evolve. This practice advisory reflects was synthesized into practice recommendations. the state of knowledge current at the time of pub- The recommendations were then graded (A lication. Given the inevitable changes in the state through D) with the ASPS Grades of Recommen- of scientific information and technology, periodic dation Scale (Table 2)8; grades correspond to the review and revision will be necessary. levels of evidence provided by the supporting literature for that recommendation. Practice TRIGGERING OF MALIGNANT recommendations are discussed throughout this HYPERTHERMIA document, and graded recommendations are Anesthetic drugs that trigger malignant hyper- summarized in Appendix A. thermia include halothane, enflurane, isoflurane, desflurane, sevoflurane, and succinylcholine (Ta- 9 DISCLAIMER ble 3). Desflurane and sevoflurane are less potent triggers, producing a more gradual onset of ma- Practice advisories are strategies for patient lignant hyperthermia.10,11 The onset may be ex- management, developed to assist physicians in plosive if succinylcholine is used.12 clinical decision-making. This practice advisory, Volatile anesthetics and succinylcholine rep- based on a thorough evaluation of the present resent a stress for skeletal muscle because they scientific literature and relevant clinical experi- ϩ perturb membranes and disturb Ca2 homeosta- ence, describes a range of generally acceptable sis. In general, normal muscle can withstand and approaches to diagnosis, management, or preven- compensate for these stresses. In susceptible mus- tion of specific diseases or conditions. This prac- cle, however, these membrane changes induced tice advisory attempts to define principles of prac- by halothane (or depolarization induced by suc- tice that should generally meet the needs of most cinylcholine) may cause an earlier calcium release patients in most circumstances. However, this that strikingly stimulates a calcium cascade.13 practice advisory should not be construed as a ϩ When these abnormal amounts of Ca2 build up rule, nor should it be deemed inclusive of all in the myoplasm, the muscle remains in a con- proper methods of care or exclusive of other tracted state, producing abnormal amounts of lac- methods of care reasonably directed at obtaining tic acid, carbon dioxide, phosphate, and heat. the appropriate results. It is anticipated that it will This will result in metabolic acidosis, hypercapnia, be necessary to approach some patients’ needs in hyperphosphatemia, and fever in the patient with different ways. The ultimate judgment regarding a malignant hyperthermia crisis. As myoplasmic the care of a particular patient must be made by ϩ Ca2 remains elevated, it will prevent the myosin the physician in light of all the circumstances pre- and actin fibrils in the muscle from detaching and sented by the patient, the diagnostic and treat- sliding back to their relaxed position. When myo- ment options available, and available resources. ϩ plasmic Ca2 levels increase further, mitochondria This practice advisory is not intended to define are uncoupled and adenosine triphosphate pro- or serve as the standard of medical care. Standards duction decreases, whereas the consumption of both adenosine triphosphate and oxygen in- Table 1. Evidence Rating Scale for Studies Reviewed creases. As adenosine triphosphate becomes scarce, the function of ion transport systems of the Level of Evidence Qualifying Studies sarcolemmal membrane ceases. Ions such as po- I High-quality, multicentered or single-centered, tassium, phosphate, and magnesium, and myoglo- randomized controlled trial with adequate bin, begin to leak across the sarcolemma into the power; or systematic review of these studies extracellular fluid, causing a rise in serum levels II Lesser quality, randomized controlled trial; 14 prospective cohort study; or systematic review (Fig. 1). of these studies III Retrospective comparative study; case-control GENETICS OF MALIGNANT study; or systematic review of these studies HYPERTHERMIA IV Case series V Expert opinion; case report or clinical Malignant hyperthermia is an inherited skel- example; or evidence based on physiology, etal muscle disorder. Genetic evaluation is con- bench research, or “first principles” sistent with autosomal dominant inheritance 69S Plastic and Reconstructive Surgery • October Supplement 2009 Table 2. Scale for Grading Recommendations Grade Descriptor Qualifying Evidence Implications for Practice A Strong Level I evidence or consistent Clinicians should follow a strong recommendation recommendation findings from multiple studies of unless a clear and compelling rationale for an levels II, III, or IV alternative approach is present. B Recommendation Levels II, III, or IV evidence and Generally, clinicians should follow