A Case of Malignant Hyperthermia in a Child Encountered during a Humanitarian Assistance Mission to the Philippines

Military Medicine, Aug 2008 by Plurad, David, Blaschke, Gregory, Jones, Shari, Pfeiffer, James

ABSTRACT Potentially fatal operating room events have become largely preventable with advances in anesthesia and surgical technique. Nonetheless, some lethal emergencies remain unpredictable and can occur whenever general anesthesia is given. We describe a case of malignant hyperthermia encountered and treated during surgical operations concurrent with an overseas humanitarian assistance mission. This case highlights the clinical diversity of malignant hyperthemia as well as the importance of preparation for any potential adverse event wherever trigger agents may be used from the mundane to exotic locales.

INTRODUCTION

Potentially fatal operating room events have become infrequent and preventable with advances in anesthesia and surgical technique. Despite this, certain lethal emergencies remain unpredictable and can occur anywhere general anesthesia is administered. Malignant hyperthermia (MH) is a rare genetic reaction to volatile anesthetics and depolarizing muscle relaxants causing profound hypermetabolism that can quickly lead to death. Administration of the skeletal muscle relaxant, dantrolene (Dantrium; P&G Pharmaceuticals, Cincinnati, Ohio), active cooling measures, and close supportive care are the mainstays of treatment. We describe a case of MH encountered and treated while aboard a U.S. Navy amphibious ship during surgical operations concurrent with an overseas humanitarian assistance mission.

CASE REPORT

A 13-month-old girl was evaluated for repair of a cleft lip and palate. This child was accompanied by her mother who reported a full-term uncomplicated pregnancy. The child was gaining weight appropriately and had no previous surgical intervention. Her mother reported no previous exposure to anesthetic agents in herself or family members. On examination, the child appeared to be behaving normally (although mildly delayed by American cultural and medical standards) but had a combined cleft lip and palate deformity. There were no signs of common viral respiratory ailments and the lungs were clear. The abdomen was soft, there were no hernias. There were no other congenital deformities present. The patient was scheduled to have repair by a team of military and civilian surgeons aboard a U.S. military amphibious ship underway nearby.

Patients are typically admitted the evening before surgery, after having been flown aboard the ship from landing zones close to their homes. They would then have preoperative studies done. However, due to logistic issues, this patient was transported to the ship the morning of her planned surgery where laboratory work and films were performed. In the immediate preoperative phase, her mother reported that the child had "a cough" but on examination, the child had no fever, nasal discharge, or respiratory distress. Chest X-ray (CxR) was negative. The white blood cell (WBC) count was 19.0. The operating surgeon and anesthetist re-evaluated the child and, given other normal findings, elected to proceed with the case. Preoperative vitals were blood pressure 104/70, heart rate 122, respiratory rate 30, temperature 35.9�C, 100% saturation on room air. The child was given preoperative antibiotics.

She underwent mask induction and subsequent maintenance with sevoflurane (Ultane; Abbot Laboratories, Abbot Park, Illinois). No depolarizing muscle relaxant was given. The repair was uncomplicated. The palate repair was facilitated via bilateral mucoperiosteal flaps and lip by rotational/ advancement flaps. However, the child had not emerged from anesthesia after 30 minutes of termination of the procedure (2.5 hours after sevoflurane exposure). At this time, end-tidal CO2 (ETCO^sub 2^) was 50 to 55 mm Hg. She remained intubated but had spontaneous respirations. Sevoflurane concentration was 0.1 vol%. She was empirically treated with glucose and, a short time later, naloxone (Narcan; Endo Pharmaceuticals, Chadds Ford, PA, Pennsylvania) for possible narcosis as the etiology for her failure to emerge. Roughly 30 minutes later (1 hour after the case and 3 hours after sevoflurane exposure), the child exhibited disconjugate gaze and stiffening of the extremities. She was treated for presumed seizures with midazolam (Versed; Roche Laboratories Nutley, NS, New Jersey) and propofol (Diprivan; AstraZeneca, Wilmington, Delaware). The pediatric service was consulted. Almost concomitantly, her heart rate increased from baseline 135 to 200 ( ), and was sustained. She remained intubated as she continued to exhibit central nervous system depression. Shortly thereafter, a rise in ETCO^sub 2^ was noted to 76 mm Hg, eventually peaking at 90 mm Hg at ~4.25 hours after exposure to the anesthetic agent. Her anesthetist continued with more vigorous hand-assisted ventilation as ETCO^sub 2^ increased. This increasing ETCO^sub 2^ was accompanied by a rapidly increasing temperature and a presumed diagnosis of MH was made. Her temperature eventually peaked at 40.3�C 4.75 hours after sevoflurane but treatment had already been instituted and the MH hotline was contacted before this. Ice packs were applied and iced gastric lavage was started (Fig. 1). Dantrolene was given (2.5 mg/kg) for 2.5 doses as intravenous access was temporarily lost during the event.