Sodium nitroprusside enhanced cardiopulmonary resuscitation improves survival with good neurological function in a porcine model of prolonged cardiac arrest

Abstract

Objective: To assess the effectiveness of sodium nitroprusside (SNP)-"enhanced" cardiopulmonary resuscitation (SNPeCPR) on 24-hr survival rates compared to standard CPR in animals after cardiac arrest. SNPeCPR consists of large intravenous SNP bolus doses during CPR enhanced by active compression-decompression CPR, an inspiratory impedance threshold device (ITD), and abdominal binding (AB). The combination of active compression-decompression CPR+ITD+AB without SNP will be called "enhanced" or eCPR.

Design: Randomized, blinded, animal study.

Setting: Preclinical animal laboratory.

Subjects: Twenty-four female farm pigs (30 ± 1 kg).

Interventions: Isoflurane anesthetized and intubated pigs were randomized after 8 mins of untreated ventricular fibrillation to receive either standard CPR (n = 8), SNPeCPR (n = 8), or eCPR (n = 8) for 25 mins followed by defibrillation.

Measurements and main results: The primary end point was carotid blood flow during CPR and 24-hr survival with good neurologic function defined as an overall performance category score of ≤2 (1 = normal, 5 = brain dead or dead). Secondary end points included hemodynamics and end-tidal CO2. SNPeCPR significantly improved carotid blood flow and 24-hr survival rates with good neurologic function compared to standard CPR or eCPR (six of eight vs. zero of eight vs. one of eight, p < .05). The improved survival rates were associated with higher coronary perfusion pressure and ETco2 during CPR.

Conclusion: In pigs, SNPeCPR significantly improved hemodynamics, resuscitation rates, and 24-hr survival rates with good neurologic function after cardiac arrest when compared with standard CPR or eCPR alone.

Figures

Figure 1

Protocol timelines. ROSC, return of spontaneous circulation; S-CPR, standard cardiopulmonary resuscitation, ACD+ITD, active compression-decompression CPR with an inspiratory impedance threshold device; AB, abdominal binding; SNP, sodium nitroprusside; VF, ventricular fibrillation; epi., epinephrine. (The combination of ACD CPR+ITD+AB is called “enhanced” eCPR.) Electric bolt sign, DC cardioversion.

Figure 2

Carotid blood flow and end-tidal CO2. Carotid blood flow (mL/min) (A), end-tidal CO2 (Torr) (B), and coronary perfusion pressure (mm Hg) (C) with sodium nitroprusside-enhanced cardiopulmonary resuscitation (SNPeCPR), CPR enhanced by active compression-decompression CPR, an inspiratory impedance threshold device, and abdominal binding without SNP (eCPR), and standard CPR (S-CPR) over 25 mins of CPR. *Statistically significant difference with a p value of <.05 compared to SNPeCPR. †Significant difference with a p value of <.05 between eCPR and S-CPR. epi., epinephrine.

Figure 3

Overall performance category score and 24-hr survival. Overall performance category score at 24 hrs after 25 mins with sodium nitroprusside-enhanced cardiopulmonary resuscitation (SNPeCPR), CPR enhanced by active compression-decompression CPR, an inspiratory impedance threshold device, and abdominal binding without SNP (eCPR), and standard CPR (S-CPR). *p < .05 compared to SNPeCPR.