Hypothermia EKG

Hi all, winter is coming,

The above patient is brought into Resus 52 by EMS as a notification for both a stroke and STEMI. You aren't able to a history as he appears obtunded, and you obtain the following EKG.

An Osborn wave (late delta wave, J-wave) is a characteristic (but not pathognomonic) finding of hypothermia at temperatures lower than 32C. It is a positive deflection at the J-point (between QRS complex and ST segment) most prominent in the precordial leads. There is correlation with the degree of hypothermia and the magnitude of the osborn wave which resolves with rewarming. Other situations this can occur are hypercalcemia, neurological injury, certain medications, and as a normal finding.  Other EKG findings in hypothermia are shivering artifact, bradycardia, and prolonged PR, QRS, ST segments.

Mild hypothermia (32-35C) presents as shivering and some drowsiness. In these patients, initiate passive external rewarming measures (warm blankets).

Moderate hypothermia (28-32C) presents as loss of shivering and progressive lethargy. Vitals signs begin to be affected with a drop in HR and cardiac output.

Severe hypothermia (<28C) presents with coma and severely depressed cardiopulmonary function. Arrhythmias and cardiac arrest (a-fib, v-fib, asystole) start to occur at this point as well. Rewarming may be needed to achieve ROSC. For moderate and severe hypothermia, you'll want to use active external rewarming (Bair Hugger) and active internal rewarming. For the latter, methods include warm IV fluids, warmed humidified air, bladder lavage, gastric lavage. On the more extreme side you could also do peritoneal lavage, pleural lavage, or ECMO (most rapid rewarming technique).

(subtle resolution of J wave)

Sources

LIFTL, Osborn Wave; lifeinthefastlane.com/ecg-library/basics/osborn-wave-j-wave/

Smith, Steve Osborn waves and hypothermia. hqmeded-ecg.blogspot.com/2011/11/osborn-waves-and-hypothermia.html

Rosh Review

Unstable Cervical Fractures

Today's POTD is on trauma, which will be the topic every Tuesday. The mnemonic to remember unstable C-spine fractures and dislocations is "Jefferson bit off a hangman's thumb."

Jefferson burst fracture - Axial loading force (diving) transmitted to C1 causing a bilateral fracture of the ring.

- Associated with other cervical fractures, vertebral aa injury.

Bilateral facet dislocation - Hyperflexion injury (rapid deceleration) causing anterior dislocation of superior vertebral body by 50% of the body's AP diameter. - Anterior and posterior ligaments are disrupted.

Odontoid type II and type III fractures

- Fracture of the dens of C2 - Type II - fracture through waist, or base of odontoid near attachment to C2 - Type III - extension of fracture to the upper portion of body

(type 3)

Atlanto-occipital dissociation

- Called "internal decapitation" because it is frequently fatal.

- Flexion injury with injury to ligaments stabilizing atlanto-occipital joint.

Hangman's fracture - Extreme hyperextension injury - MVC, diving, judicial hangings. - Bilateral C2 pedicle fracture, causing anterior dislocation of C2 vertebral body onto C3.

Teardrop fracture - Hyperextension of the anterior longitudinal ligament avulsing a teardrop fragment of the body.

- Or hyperflexion causing the vertebrae bodies to collide and form a teardrop fragment of the superior vertebrae displacing the body and disrupting the posterior longitudinal ligament.

Sources

Rosen's (ed 8), ch 43

Rosh Review

Young, N, et al. Unstable spine fractures (wikem.org/wiki/Unstable_spine_fractures)

Carbon Monoxide Poisoning

 

Signs and symptoms of CO poisoning are non-specific and can range from flu-like symptoms (headache is most common) to coma. While usually thought of in the winter months due to space heaters, they can occur throughout the year. Therefore, clinical suspicion is paramount in diagnosis, especially with patients presenting from a fire.

CO binds to Hgb with 200x greater affinity than oxygen. Therefore, labs can show a metabolic acidosis and elevated lactate due to a shift to anaerobic metabolism. COHb levels are considered toxic if >3% in nonsmokers, and >10% in smokers. Symptoms and COHb levels do not correlate well and pulse oximetry is unreliable (check a vbg and the pulse CO-oximeter). Also order a pregnancy test, EKG/trop for ischemia/arrhythmias, CK for rhabdo, CXR if concerned for pulmonary edema, and CT/MRI if there are neurologic changes.

For treatment, as you should know, ABCs are first. Intubate if necessary as patients these patients may have smoke inhalation injuries. Then initiate 100% O2 with a NRB (or through the ETT) as it reduces the half-life of CO from 4 hours to 60-90 minutes. If the patient is only mildly symptomatic, they can be discharged after 4 hours of observation, symptom resolution, and return of COHb level to normal. COHb levels of >25% (>15% in pregnant patients) should make you think about hyperbaric oxygen therapy (board world). In the real world, if a patient has severe symptoms (LOC, AMS, coma, cardiac ischemia), you should consider HBO. There is controversy regarding if it actually reduces the risk of neuropsychiatric sequelae (Parkinsonian features, seizure disorders, intellectual impairment). For patients that fall in between these two presentations, consider admission for continued oxygen therapy and normalization of COHb levels.

Sources: Tintinalli (7e) Ch 217 Rosen’s (8e) Ch 159 FOAMCAST - Cyanide and CO Toxicity (foamcast.org/2014/05/) Simon, Erica; Carbon Monoxide Poisoning(www.emdocs.net/em3am-carbon-monoxide-toxicity/)