Mon25October0844PM 8

A 54-year-old man is admitted to the Emergency department following a VF arrest at his local gym. Basic life support was promptly instituted, followed by a successful DC cardioversion and insertion of a supraglottic airway device by a paramedic.

The patient's pulse rate is 120 beats per minute, blood pressure 130 mmHg and a Glasgow coma score of 8. The patient is sedated, intubated and ventilated and transferred to the intensive care unit.

Which one of the following management options is associated with improved neurological outcome?

(Please select 1 option)

Ventilate the patient and adjust the PaCO to approximately 4.7 kPa Incorrect answer selected

Reduce the cerebral metabolic rate using a thiopentone infusion

Ventilate the patient with 100% oxygen for 12 hours

Cool the patient to 32-36°C for >24 hours This is the correct answer

Maintain tight glucose control 4.5-6 mmol/L with a dextrose/insulin infusion

Explanation

There is evidence that cooling patients to 32-34°C for 12-24 hours following out-of-hospital cardiac arrest from VF arrest is associated with improved neurological outcome. Whilst it is possible that the cerebral metabolic rate for oxygen (CMRO2) might be reduced in the healthy brain it has not been proven in animal studies following cardiac arrest.

Hypothermia reduces the deleterious effects of reperfusion injury (inhibiting the release of damaging excitatory aminoacids such as glutamate and the accumulation of oxygen free radicals).

There is evidence that hyperoxia following the return of spontaneous circulation might be deleterious, so ventilating the patient with 100% oxygen is inappropriate. Oxygen saturations should be maintained between 94% and 98%. There are no data to support the targeting of specific PaCO2 values.

Hypercarbia can lead to cerebral vasodilatation and increase intracranial volume and pressure. PaCO2 should be normal and adjusted in light of blood gas values. "Tight" blood glucose control in general intensive care is associated with increased 90-day mortality and the likelihood of hypoglycaemia. Hypoglycaemia and hyperglycaemia >10 mmol/L) should be avoided.

Thiopentone, when given at infusion rates sufficient to suppress EEG activity reduces CMRO2 by 30-50%. Its long half life following infusion prevents prompt neurological examination when stopped. It also produces a fall in mean arterial pressure thereby reducing cerebral perfusion. There is no evidence that its routine use following cardiac arrest is accompanied by improved survival.

Reference:

Hypothermia after Cardiac Arrest Study Group. Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. N Engl J Med. 2002;346:549-56.

Therapeutic hypothermia following cardiac arrest Interventional procedures guidance

Published: 23 March 2011

https://www.nice.org.uk/guidance/ipg386/resources/therapeutic-hypothermia-following-cardiac-arrest-pdf-1899867818452165

Answer Statistics

1

31%

2

2%

3

1%

4

64%

5

5%

Times answered: 279