Sun31October0735PM 6

In comatose survivors of cardiac arrest:

True / False

Therapeutic hypothermia is indicated only following in-hospital VF arrests Correct

Neurological outcome is better if post-arrest therapeutichypothermia of 33 degrees is used compared with 36 degrees centigrade Correct

The absence of the N20 spike bilaterally in somatosensory-evoked potentials can be used to predict poor neurological outcome Correct

Pneumonia is a frequent complication Correct

Patients should be ventilated with an FiO2 of 1.0 for at least an hour following return of spontaneous circulation Correct

Explanation

The inspired oxygen concentration should be titrated to SpO2 of 94-96%, as hyperoxia has been associated with worse neurological outcome.

Pneumonia is a common complication occurring in up to 50% of comatose patients following out-of-hospital cardiac arrest, often due to aspiration.

A stimulus applied to a peripheral nerve, such as the median nerve, can be detected at the cortical level so testing the somatosensory pathway integrity. This can be useful to localise an abnormality or track any changes. It has also been shown to be useful in aiding prognostication in comatose patients following cardiac arrest.

The absence of the N20 component has been shown to be a reliable predictor of poor outcome; however the test is not widely available.

Much of the evidence about timing of neurological prognostication, using pupillary and motor responses for example, has been based on patients not treated with therapeutic hypothermia. Caution should therefore be used when applying to this group of patients.

Hypothermia alters the clearance and metabolism of many drugs including sedatives and the aim of the treatment is to alter the progression of brain injury. It is likely that prognostication should be delayed, though the ideal timing is unclear.

Therapeutic hypothermia is the only therapy proven to improve survival following cardiac arrest. There are two randomised controlled trials showing improved outcomes in comatose survivors of out-of-hospital ventricular fibrillation cardiac arrest1 and other observational and historical analyses that suggest benefit in other rhythms and following in-patient cardiac arrests.

Pooled data from studies show that the use of mild therapeutic hypothermia for 24-hours in patients resuscitated from non-VF/VT arrest is associated with a 15% reduction in hospital mortality and with minor improvements in neurological outcome at discharge.

A recent randomised clinical trial comparing the neurologic function and health-related quality of life in patients following targeted temperature management

at 33°C vs 36°C after out-of-hospital cardiac arrest showed no difference between the two groups.

Reference:

Bernard SA, Gray TW, Buist MD, et al. Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med. 2002;346:557-63.

Nielsen N, Wetterslev J, Cronberg T, et al. Targeted temperature management at 33°C versus 36°C after cardiac arrest. N Engl J Med. 2013;369:2197-206.

Nolan JP, Neumar RW, Adrie C, et al. Post-cardiac arrest syndrome: epidemiology, pathophysiology, treatment, and prognostication. Resuscitation. 2008;79:350-79.

Neurologic Function and Health-Related Quality of Life in Patients Following Targeted Temperature Management at 33°C vs 36°C After Out-of-Hospital Cardiac Arrest. A Randomized Clinical Trial. JAMA Neurology Published online April 6, 2015.

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