Classic EKG Changes of Hypothermia

Abstract

A 51-year-old female was found lying in a wet damp area near a rural Wisconsin roadside in early spring. The patient was unresponsive and multiple empty medication bottles were found near her body. At the time of admission to the emergency department, her temperature was 80.4°F (26.8°C) with her blood pressure at 80/50 mm Hg. She was intubated for airway protection. The empty medication bottles found included prescriptions for citalopram, aripiprazole, ziprasidone, trazodone, clonazepam, oxycodone, levothyroxine and lansoprazole. She had multiple electrolyte abnormalities (potassium 2.5 mmol/L, magnesium 1.6 mg/dL, phosphate 1.3 mg/dL, and ionized calcium 4.2 mg/dL). Her EKG (figure 1 ▶) showed evidence of hypothermia with prolonged QRS and Osborne waves (arrows in figure 1 ▶), new onset atrial fibrillation, and prolonged QT (QT/QTc 740/688). Members of the emergency department staff were able to rewarm her using warm saline, radiant heat, and warm air (Bair hugger). Her body temperature slowly increased to 88.3°F (31.3°C) within the next 4 hours with significant reversal of her EKG changes (figure 2 ▶), including reverting back to sinus rhythm, normalization of QRS waves (88 milliseconds) with resolution of Osborne waves and improvement in QT (QT/QTc 504/577). By 12 hours post-admission, her temperature was raised to 99°F (37.2°C). Figure 1. Initial EKG with classic findings of hypoxia at body temperature of 80.4°F. Figure 2. Repeat EKG in next 4 hours with significant reversal of her EKG changes at body temperature of 88.3°F. The patient’s cardiac enzymes remained negative. Her comprehensive urine drug screen was positive for oxycodone, oxymorphone, trazodone, lidocaine, and citalopram. She was extubated in less than 24 hours and was discharged from hospital in 3 days. The incident was thought to be an attempted suicide, which resulted in her exposure to cold weather conditions for 24 hours. J waves (also called Osborne waves) are pathognomonic for hypothermia when present.1 These look like “delta” or “camel’s hump” waves after regular QRS complex.1 J waves or Osborne waves appear secondary to an exaggerated outward potassium current leading to repolarization abnormality.2 These waves are detectable in 80% of the patients when core body temperature is lower than 30°C.3 J waves are seen in lead II and precordial leads V2-V6.1 Similar findings can be seen in patients with hypercalcemia, Brugada syndrome, and early repolarization.1 Our patient had significant hypokalemia and it could have contributed to the prolonged QRS. It should be noted, however, that the plasma potassium levels do not generally correspond to the electrocardiographic changes of hypokalemia.4 J waves are not prognostic indicators when they are present, unlike atrial fibrillation, which incurs survival disadvantage.5 Fatal ventricular fibrillation or asystole can occur when core body temperature is below 28°C.1