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A simple model has been developed for analyzing the pulsed polarographic electrode. For short pulse durations the charge transfer kinetics must be incorporated into the boundary condition at the electrode surface. The predicted velocity dependence for long pulse durations is in good agreement with experimental data.

The low flow states and limited coronary perfusion provided by conventional cardiopulmonary resuscitation (CPR) have prompted investigations into alternative, more invasive, methods of resuscitation. Previous case reports and limited animal evidence have suggested that the intra-aortic balloon pump (IABP) may have a role in resuscitation. We used a canine cardiac arrest model to study the hemodynamic effects of the IABP during closed-chest CPR. A sensor attached to the chest plate of a Thumper was used to time a Datascope Model 3520 ventricular assist console such that the balloon inflated on the upstroke and deflated on the downstroke of the Thumper. There was no increase in systolic blood pressure with the balloon pump. Diastolic blood pressure and coronary perfusion pressure were significantly higher with the IABP. Circulation times were shorter and end-tidal CO2 was higher with the IABP. It was concluded that the IABP improves hemodynamic parameters during experimental cardiac arrest.

The proposed application of this work is to the measurement of both tissue perfusion and tissue p02 with the same Polarographic probe. It is anticipated that membrane characteristics will markedly affect the overall flow sensitivity or insensitivity of a particular probe when operated under pulsed conditions. Moreover operation with very short pulse times requires consideration of the rapid development of the “double layer” as the double layer current can be significantly larger than the current due to the Polarographic reaction. The effect of the double layer formation is specifically considered below along with the incorporation of convective phenomena in the model.

Previous reports have advocated the use of mixed venous blood gases to estimate arterial pH and as a reflection of tissue acid-based balance. However, true mixed venous samples are difficult to obtain during cardiac arrest as they require a pulmonary artery catheter. The purpose of this study was to determine whether central or femoral venous samples could be used in place of pulmonary artery samples. Blood gases from these sites were drawn at intervals during experimental cardiac arrest in dogs. The PO2, PCO2, and pH from the pulmonary artery samples were strongly correlated with those from the central venous (r = .93, .99, and .99, respectively) and from the femoral venous samples (r = .73, .93, and .97, respectively). There were no significant differences in the pulmonary artery, central, or femoral venous gases. This animal model suggests that femoral and central venous samples mirror true mixed venous blood gases from the pulmonary artery and could be used in their place.

Cardiopulmonary resuscitation requires effective, prompt drug administration. In order to analyze Advanced Cardiac Life Support (ACLS) recommendations for site of drug administration, we studied dye circulation times after central, femoral, and peripheral venous injection during both closed and open chest CPR using a canine arrest model. Measurements of circulation times were made after injection of indocyanine green dye at femoral, central, and peripheral venous sites. Circulation times during closed chest CPR were 62.7 +/- 19.6 sec after central injection, 86.6 +/- 23.5 sec after femoral injection, and 93.6 +/- 17.9 sec after peripheral injection (p less than .001). During closed chest CPR, peak dye concentration after central injection was significantly higher than that after peripheral injection (4.0 +/- 1.3 vs. 3.1 +/- 0.8 mg/L, p less than .01). Circulation times were significantly shorter during open chest CPR with times again shortest after central injection. This animal model suggests that prompt drug delivery during CPR is enhanced by central venous injection of medication. There appears to be no advantage in femoral over peripheral injection.