The effect of bolus injection on circulation times during cardiac arrest

Previous investigations have shown that peripheral injection of medication during cardiac arrest leads to prolonged circulation times and low peak drug levels. Current Advanced Cardiac Life Support guidelines suggest that administering a bolus of flush solution after injection of medication may hasten drug delivery, but there is little evidence to support this. The purpose of this study is to investigate the effect of peripheral bolus injection on circulation times during cardiac arrest. Measurements of circulation times were made following injection of indocyanine green dye both with and without a bolus of 20 mL saline flush into a peripheral vein of mongrel dogs. There was no difference in systolic, diastolic, or coronary perfusion pressures during the injections with or without bolus injection. Similarly, there was no difference in end-tidal CO2 or in arterial-venous PO2, PCO2, or pH gradient. The circulation time without bolus injection was 77.7 +/- 42.7 seconds while circulation time with the saline flush was 48.3 +/- 20.9 seconds (P less than .001). Peak dye concentration without saline flush was 3.0 +/- 1.0 mg/L, and peak dye concentration with saline flush was 3.8 +/- 0.9 mg/L (P less than .001). We conclude that a bolus injection of 20 mL of saline enhances dye circulation times and peak levels during cardiac arrest in this animal model. The clinical application of this technique warrants further investigation.