“Further studies combining vasopressin with hypothermia post-cardiac arrest can be explored to determine if this combination will have any benefits for long-term survival” suggest the authors of the report in Resuscitation online February 18.
Dr. Marcus Eng Hock, with Singapore General Hospital, and colleagues explain that in Asia, paramedics generally are not permitted to pronounce death in the field, so patients are commonly transported to the hospital with ongoing CPR and resuscitation efforts continue in the emergency department.
The team hypothesized that such patients, who would have prolonged periods in cardiac arrest, might benefit from vasopressin in addition to usual treatment with adrenaline, compared to treatment with adrenaline alone.
They therefore conducted a randomized, double-blind multicenter trial in which 727 eligible cardiac arrest patients were assigned to receive intravenous adrenaline (1 mg) or vasopressin (40 IU) in the emergency department, with additional open-label doses of adrenaline per current guidelines.
In the vasopressin group, 22.2% of patients survived to hospital admission compared with 16.7% in the adrenaline group (p=0.05), the investigators found.
However, this did not translate to improved long-term survival. Just 11 vasopressin patients (2.9%) and 8 adrenaline patients (2.2%) survived to hospital discharge
“It is interesting to note in this study, that 38 +/- 20 min after onset of cardiac arrest, ROSC could be achieved in substantial numbers of patients,” Dr. Hock and colleagues comment. “Due to the very high proportion of asystolic (~69%) and PEA (pulseless electrical activity) (~19%) patients, it is not surprising that overall survival in our study was low,” they add.
They conclude, “Further studies on the effect of vasopressin on patients with prolonged cardiac arrest are needed. In particular, our finding of improved short-term survival over adrenaline needs to be confirmed.”
It is not known if vasopressin with subsequent hypothermia could improve outcomes, they add. “If so, a stronger argument for vasopressin could be made.”