Electrocardiographic changes in hypothermia

Environmental Hypothermia

Although a rare diagnosis in the Emergency Department, hypothermia affects patients in all environments, from urban to mountainous settings. Classic signs of death cannot be interpreted in the hypothermic patient, thus resulting in the mantra, "No one is dead until they're warm and dead." This comprehensive review of environmental hypothermia covers the clinical significance and pathophysiology of hypothermia, pearls and pitfalls in the prehospital management of hypothermia (including temperature measurement techniques and advanced cardiac life support deviations), necessary Emergency Department diagnostics, available rewarming modalities including extracorporeal life support, and criteria for termination of resuscitation.

A case of fatal myxedema coma with electrocardiogram Osborne J-wave in a patient initially diagnosed with hypothyroidism

Myxedema coma is a life-threatening endocrine emergency with a high mortality rate resulting from severe insufficiency of thyroid hormones. Intravenous levothyroxine replacement is considered the standard therapy for myxedema coma in many countries. In Japan, however, although there are diagnostic criteria highly suggestive or diagnostic for myxedema coma, no management strategy has been established, despite the availability of levothyroxine. Here we report a 75-year-old man with a history of Alzheimer's disease and schizophrenia who developed somnolence and generalized edema. Except for a pulse rate of 60 bpm, his vital signs and blood oxygen level were stable. Thyroid studies showed an elevated serum thyrotropin level of 219.2 μU/mL and a decreased serum free-thyroxine level of 0.15 ng/dL. On this basis he was diagnosed as having hypothyroidism rather than being highly suggestive for myxedema coma. Daily oral levothyroxine 25 μg was initiated and increased to 50 μg 3 days later. Seven days after being started on levothyroxine, the patient suddenly developed impaired consciousness, hypoxemia, hypotension, hypothermia, and hyponatremia. Electrocardiography revealed junctional bradycardia with Osborne J-wave. Myxedema coma was therefore diagnosed. He went into cardiac arrest in the emergency room but was resuscitated. Despite subsequent intravenous administration of hydrocortisone and levothyroxine, as well as intensive supportive care, he eventually died 12 hours after hospital admission. This case illustrates some of the challenges associated with the management of patients with signs highly suggestive/diagnostic of myxedema coma, including the optimal loading dosage and intervention timing of thyroid hormone replacement.

Osborn wave in hypothermia and relation to mortality

BACKGROUND & AIM

The aim of this study was to compare hypothermia patients with and without an Osborn wave (OW) in terms of physical examination findings, laboratory results, and clinical survival.

METHODS

The study was carried out retrospectively on hypothermic patients. The hypothermic patients were divided into two groups. Group 1 comprised patients with OW on electrocardiogram (ECG), and Group 2 comprised patients without OW on ECG. The Mann-Whitney U test was used to compare the two groups, and the relationships between the variables and the presence of OW and mortality were analyzed with ANOVA. A value of p < 0.05 was considered statistically significant.

RESULTS

OW was detected on ECG of 41.9% of the patients (Group 1). The mean body temperature was 30.8 ± 4.1 °C in Group 1 and 33.3 ± 1.6 °C in Group 2 (p = 0.106). The mean creatinine level was 1.01 ± 0.6 mg/dl in Group 1 and 0.73 ± 0.5 mg/dl in Group 2 (p = 0.046). The mean bicarbonate level was 15.9 ± 3.8 mmol/l in Group 1 and 18.6 ± 3.5 mmol/l in Group 2 (p = 0.038). A relationship was determined between the presence of OW and pH, bicarbonate, and creatinine levels (p = 0.026; 0.013; 0.042, respectively). The mortality rate was 69.2% in Group 1 and 77.8% in Group 2 (p = 0.689).

CONCLUSION

Although there is a relationship between the decrease in bicarbonate levels, changes in kidney functions that cause acidosis, and the presence of OW, it has no effect on mortality. The presence of OW in hypothermic patients is insufficient to make a decision regarding mortality.

Out in the cold: the hypothermic heart response

We present an interesting case of a 49-year-old woman with hypothermia and associated Osborn waves (also called J waves) on ECG. She was found on the floor of her home and difficult to arouse. On arrival to the emergency department (ED), her rectal temperature was 87.5°F. ECG showed Osborn waves in diffuse leads. She was intubated in the ED and was started on vasopressor support for hypotension refractory to intravenous fluid boluses. She was transferred to the critical care unit for continued respiratory and cardiovascular support. With active external rewarming her core body temperature continued to improve. Blood pressure also improved and vasopressor was tapered off. She was extubated and was transferred to the medical floor for continued supportive care. Osborn waves on ECG resolved within 12 h of achieving normal range body temperature. The patient was eventually discharged home with medical follow-up.

The pathophysiological mechanisms of the onset of death through accidental hypothermia and the presentation of "The little match girl" case

Hypothermia and death caused by hypothermia may be found in a number of fiction works, mainly in novels. In the well-known story “The Little Match Girl” by Hans Christian Andersen, one can notice that the descriptions of the phenomena occurring before the girl’s death are in fact a literary presentation of the pathophysiological mechanisms of the onset of death through accidental hypothermia. This essay presents the medical aspects of the story written by Andersen.

Practical pharmacologic aspects of therapeutic hypothermia after cardiac arrest

Abstract Therapeutic hypothermia has emerged as an effective means of improving neurologic outcomes among cardiac arrest survivors. To achieve optimal results, clinicians must understand and anticipate potential adverse effects of cooling and provide rigorous monitoring and/or pharmacologic interventions as appropriate. Using pharmacotherapy to counter adverse effects of cooling or to treat an intrinsic process under hypothermic conditions requires understanding how hypothermia will influence the clinical effects of the drug, including the drug's pharmacokinetics and pharmacodynamics. The pharmacologic aspects of therapeutic hypothermia in relation to physiology and adverse effects are reviewed.

Osborn Waves in Sepsis

A patient with severe sepsis, who presented with moderate hypothermia and the classical electrocardiographic findings that have been described in patients with accidental hypothermia is presented. Rewarming was associated with proportional improvement of the initial electrocardiographic abnormalities. A brief discussion is included about the electrophysiologic mechanisms of Osborn waves, the differential diagnosis of this electrocardiographic finding as well as other findings described in patients with hypothermia.

Electrocardiographic changes by accidental hypothermia in an urban and a tropical region

BACKGROUND

Hypothermia is defined as a condition in which core temperature (rectal, esophageal, or tympanic) reaches values below 35 degrees C. This may be accidental, metabolic, or therapeutic. The accidental form is frequent in cold-climate countries and rare in those with tropical or subtropical climate. The aim of this study was to evaluate electrocardiographic changes of patients with accidental hypothermia.

METHODS

In 59 patients with hypothermia, the following electrocardiogram parameters were analyzed: rhythm and heart rate (HR), P-wave characteristics, PR-interval duration, QRS-complex duration, presence of J wave and its location characteristics, polarity, voltage, aspect and its correlation with the degree of hypothermia, changes in T wave regarding its polarity and characteristics, duration of the QT interval corrected for HR using both Bazett and Friderica formulas, and possible presence of both supraventricular and ventricular arrhythmias were independently and blindly analyzed in the tracings by experienced cardiologists.

RESULTS

In 6 patients, electrocardiogram was normal. Sinus bradycardia was observed in 52.5% of the patients. J wave was present in 51 patients, and its voltage correlated inversely and was statistically significantly with the core temperature. Changes in T wave were observed in 47.4% of the cases. QT interval, adjusted for HR, was prolonged in 72.8% of the cases. Idioventricular rhythm was found in 6 cases, total atrioventricular block in 3 cases, and junctional rhythm and atrial fibrillation in 2 patients.

CONCLUSIONS

Electrocardiogram changes in accidental hypothermia are frequent and characteristic for this entity improving diagnosis in usually unconscious patients, and in many cases, it may be the diagnostic clue in patients with conscience deficit in emergency units, even in patients from a tropical climate where the population at risk may be exposed to temperatures below 20 degrees C.