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Osborn Waves on EKG in hypothermic patient

Aaron Richler, MD, Carlos A. Morales-Mangual, MD

Novermber 16, 2019

A 36-year-old male with a medical history of HIV, schizophrenia, and bipolar disorder presented to the emergency department (ED) after being found unresponsive on the street. In the ED, the patient was found to be profoundly hypothermic with a core body temperature 80.3oF (26.8o C). Initial laboratory values showed Hgb 10.9 (g/dL) (Ref: 13.4-15.4 g/dL), PLT 110 10x9/L (Ref: 153-328 10x9/L), INR 1.5 (Ref: 0.70-1.20), BUN 9 mg/dL (Ref: 9.0-20.0 mg/dL), creatinine 1.21 mg/dL (Ref: 0.66-1.25 mg/dL), lactic acid >12 mmol/L (Ref: 0.70-2.10 mmol/L), high anion gap metabolic acidosis, alcohol level of 151mg/dL (Ref: 0.00-10.00 mg/dL), CPK 2503 U/L (Ref: 30-135 U/L), ALT 280 U/L (Ref: 9-52 U/L), AST 288 U/L (Ref: 14-36 U/L), and VBG pH 6.93 (Ref: 7.38-7.42). A 12-lead EKG (A) was obtained and showed sinus rhythm with 1st degree AV block, non-specific intra-ventricular conduction block, nonspecific T-wave abnormalities and prolonged QT interval with Osborn waves, a late upright terminal deflection of the QRS complex. While rewarming, the patient went into ventricular fibrillation arrest. Advanced cardiopulmonary support was initiated for 46 minutes, during which the patient was defibrillated multiple times and endotracheally intubated. The rewarming process was continued with insertion of bilateral chest tubes and warm bladder irrigation. After the patient was rewarmed a repeat 12-lead EKG (B) showed normal sinus rhythm with early repolarization. On admission to the MICU a few hours later, the patient was noted to be responsive to verbal commands and later that evening the patient self-extubated. Post-extubation the patient was fully oriented to time and place and without gross neurological deficits. Over the next 12 hours, the patient was weaned off of inotropic support with subsequent normalization of renal function, lactate and troponins levels. On transfer to the telemetry unit, the patient admitted to excessive alcohol consumption on the night of the incident but denied use of illicit drugs. Additional work-up consisted of a transthoracic echocardiogram demonstrating normal left ventricular ejection fraction and no structural abnormalities; 24-hour Holter monitoring with absence of significant arrhythmias; and cardiac catheterization, which showed no evidence of coronary artery disease. He was discharged home 14 days after admission.

A- Sinus rhythm with 1st degree AV block, non-specific intra-ventricular conduction
block, nonspecific T-wave abnormality and prolonged QT with Osborn waves

B- Normal sinus rhythm and early repolarization


A 44-year-old male was found unconscious and submerged under water with a body temperature of 30°C [86°F] on EMS arrival.  EKG showed positive deflections at the J point. Patient was brought to the emergency department and rewarming was initiated. Once rewarming was started, the patient went into ventricular fibrillation requiring cardiopulmonary resuscitation. What is the best next step in management?

  1. Continue CPR with unsynchronized cardioversion

  2. Continue CPR and stop rewarming 

  3. Cardiology consult for emergent cardiac catheterization 

  4. Continue CPR and synchronized cardioversion

  5. Pronounce death after 4 cycles of CPR given medical futility


A. Continue CPR with unsynchronized cardioversion

Teaching Point:

Rewarming hypothermic patients can cause ventricular arrhythmias.1

In patients status post cardiac arrest with severe hypothermia defined as a body temperature <30°C [86°F], there is a neuroprotective affect from the hypothermia secondary to the decreased metabolic requirements of cells at low temperatures. For this reason, American Heart Association protocol recommends avoiding interruption of ACLS in hypothermic patients status post cardiac arrest until the body has been rewarmed. 2-4 . Electrocardiographic findings in hypothermic patients include a prolongation of PR; QRS; and QT intervals and Osborn waves (J-waves or “camel hump signs”), which can be described as a late upright terminal deflections of the QRS complex5. It is important to recognize Osborn waves since there is an association with arrythmias, especially ventricular fibrillation in hypothermic patients.  Osborn waves may also be appreciated in conditions such as hypercalcemia, subarachnoid hemorrhage or vasospactic angina, but in these disease states malignant arrythmias are usually absent.


  1. Maruyama M, Kobayashi Y, Kodani E, et al. Osborn Waves: History and Significance. Indian Pacing and Electrophysiology Journal. 2004;4(1):33-39.

  2. Arrich J, Holzer M, Havel C, Müllner M, Herkner H. Hypothermia for neuroprotection in adults after cardiopulmonary resuscitation. Cochrane Database of Systematic Reviews 2016, Issue 2. Art. No.: CD004128. DOI: 10.1002/14651858.CD004128.pub4.

  3. Gilbert M, Busund R, Skagseth A, Nilsen PÅ, Solb⊘ JP. Resuscitation from accidental hypothermia of 13.7°C with circulatory arrest. Lancet. 2000;355:375–376.

  4. “Cardiac Arrest in Accidental Hypothermia.” ECC Guidelines 2015, American Heart Association, 10 Oct. 2010,

  5. O'Keefe, J. (2008). The complete guide to ECGs. Royal Oak, Mich.: Physicians' Press.


Aaron Richler, MD and Carlos A. Morales-Mangual, MD at the time of submission were internal medicine residents at Brookdale University Hospital in New York.  Their research interests include cardiovascular disease and cardiac arrhythmias.