Sodium nitroprusside-enhanced cardiopulmonary resuscitation improves resuscitation rates after prolonged untreated cardiac arrest in two porcine models

Abstract

Objective: Sodium nitroprusside-enhanced cardiopulmonary resuscitation consists of active compression-decompression, an impedance threshold device, abdominal binding, and large intravenous doses of sodium nitroprusside. We hypothesize that sodium nitroprusside-enhanced cardiopulmonary resuscitation will significantly increase carotid blood flow and return of spontaneous circulation compared to standard cardiopulmonary resuscitation after prolonged ventricular fibrillation and pulseless electrical activity cardiac arrest.

Design: Prospective randomized animal study.

Setting: Hennepin County Medical Center Animal Laboratory.

Subjects: Forty Yorkshire female farm-bred pigs weighing 32 ± 2 kg.

Interventions: In protocol A, 24 isoflurane-anesthetized pigs underwent 15 mins of untreated ventricular fibrillation and were subsequently randomized to receive standard cardiopulmonary resuscitation (n = 6), active compression-decompression cardiopulmonary resuscitation + impedance threshold device (n = 6), or sodium nitroprusside-enhanced cardiopulmonary resuscitation (n = 12) for up to 15 mins. First defibrillation was attempted at minute 6 of cardiopulmonary resuscitation. In protocol B, a separate group of 16 pigs underwent 10 mins of untreated ventricular fibrillation followed by 3 mins of chest compression only cardiopulmonary resuscitation followed by countershock-induced pulseless electrical activity, after which animals were randomized to standard cardiopulmonary resuscitation (n = 8) or sodium nitroprusside-enhanced cardiopulmonary resuscitation (n = 8).

Measurements and main results: The primary end point was carotid blood flow during cardiopulmonary resuscitation and return of spontaneous circulation. Secondary end points included end-tidal CO2 as well as coronary and cerebral perfusion pressure. After prolonged untreated ventricular fibrillation, sodium nitroprusside-enhanced cardiopulmonary resuscitation demonstrated superior rates of return of spontaneous circulation when compared to standard cardiopulmonary resuscitation and active compression-decompression cardiopulmonary resuscitation + impedance threshold device (12 of 12, 0 of 6, and 0 of 6 respectively, p < .01). In animals with pulseless electrical activity, sodium nitroprusside-enhanced cardiopulmonary resuscitation increased return of spontaneous circulation rates when compared to standard cardiopulmonary resuscitation. In both groups, carotid blood flow, coronary perfusion pressure, cerebral perfusion pressure, and end-tidal CO2 were increased with sodium nitroprusside-enhanced cardiopulmonary resuscitation.

Conclusions: In pigs, sodium nitroprusside-enhanced cardiopulmonary resuscitation significantly increased return of spontaneous circulation rates, as well as carotid blood flow and end-tidal CO2, when compared to standard cardiopulmonary resuscitation or active compression-decompression cardiopulmonary resuscitation + impedance threshold device.

Figures

Figure 1. Intra-CPR Left Ventricular Dimensions in S-CPR and SNPeCPR

all measurements are recorded at end-diastole (end of thoracic decompression). The blue arrow represents the LV cavity dimensions and the red arrow represents the interventricular septal thickness. * means statistically significant difference with p

Figure 1. Intra-CPR Left Ventricular Dimensions in S-CPR and SNPeCPR

all measurements are recorded at end-diastole (end of thoracic decompression). The blue arrow represents the LV cavity dimensions and the red arrow represents the interventricular septal thickness. * means statistically significant difference with p

Figure 2. Carotid Blood Flow and End-Tidal CO2

(A) Carotid blood flow at baseline, during chest-compression only CPR, and during advanced cardiac life support in protocol B. Note the significant increase in flow during ACLS in animals receiving SNPeCPR compared to S-CPR. (B) End-tidal CO2 at baseline, during chest-compression only CPR, and during ACLS. Note the significant increase in ETCO2 in animals receiving SNPeCPR compared to S-CPR. * means statistically significant difference with p<0.05 compared to SNPeCPR.

Figure 2. Carotid Blood Flow and End-Tidal CO2

(A) Carotid blood flow at baseline, during chest-compression only CPR, and during advanced cardiac life support in protocol B. Note the significant increase in flow during ACLS in animals receiving SNPeCPR compared to S-CPR. (B) End-tidal CO2 at baseline, during chest-compression only CPR, and during ACLS. Note the significant increase in ETCO2 in animals receiving SNPeCPR compared to S-CPR. * means statistically significant difference with p<0.05 compared to SNPeCPR.