The physiologic response to rescue therapy with vasopressin versus epinephrine during experimental pediatric cardiac arrest

Aim: Compare vasopressin to a second dose of epinephrine as rescue therapy after ineffective initial doses of epinephrine in diverse models of pediatric in-hospital cardiac arrest. Methods: 67 one- to three-month old female swine (10−30 kg) in six experimental cohorts from one laboratory received hemodynamic-directed CPR, a resuscitation method where high quality chest compressions are provided and vasopressor administration is titrated to coronary perfusion pressure (CoPP) ≥20 mmHg. Vasopressors are given when CoPP is <20 mmHg, in sequences of two doses of 0.02 mg/kg epinephrine separated by minimum one-minute, then a rescue dose of 0.4 U/kg vasopressin followed by minimum two-minutes. Invasive measurements were used to evaluate and compare the hemodynamic and neurologic effects of each vasopressor dose. Results: Increases in CoPP and cerebral blood flow (CBF) were greater with vasopressin rescue than epinephrine rescue (CoPP: +8.16 [4.35, 12.06] mmHg vs. + 5.43 [1.56, 9.82] mmHg, p = 0.02; CBF: +14.58 [-0.05, 38.12] vs. + 0.00 [-0.77, 18.24] perfusion units (PFU), p = 0.005). Twenty animals (30%) failed to achieve CoPP ≥20 mmHg after two doses of epinephrine; 9/20 (45%) non-responders achieved CoPP ≥20 mmHg after vasopressin. Among all animals, the increase in CBF was greater with vasopressin (+14.58 [-0.58, 38.12] vs. 0.00 [-0.77, 18.24] PFU, p = 0.005). Conclusions: CoPP and CBF rose significantly more after rescue vasopressin than after rescue epinephrine. Importantly, CBF increased after vasopressin rescue, but not after epinephrine rescue. In the 30% that failed to meet CoPP of 20 mmHg after two doses of epinephrine, 45% achieved target CoPP with a single rescue vasopressin dose.