EFFECT OF DIFFERENT COMPRESSION-DECOMPRESSION CYCLES ON HEMODYNAMICS DURING ACD-CPR IN PIGS

The haemodynamic effects of variations in the relative duration of the compression and active decompression (4 cm/2 cm) during active compre ssion-decompression cardiopulmonary resuscitation (ACD-CPR), 30/70, 50 /50 and 70/30, were tested in a randomized cross-over design during ve ntricular fibrillation in seven anaesthetized pigs (17-23 kg) using an automatic hydraulic chest compression-decompression device. Duty cycl es of 50/50 and 70/30 gave significantly higher values than 30/70 for mean carotid blood flow (32 and 36 vs. 21 mi min(-1), transit time flo w probe), cerebral blood flow (30 and 34 vs. 19, radionuclide microsph eres), mean aortic pressure (35 and 41 vs. 29 mmHg) and mean right atr ial pressure (24 and 33 vs. 16 mmHg). A higher mean aortic, mean right atrial and mean left ventricular pressure for 70/30 were the only sig nificant differences between 50/50 and 70/30. There were no difference s in myocardial blood flow (radionuclide microspheres) or coronary per fusion pressure (CPP, aortic-right atrial pressure) between the three different duty cycles. CPP was positive in both the early and late com pression period and during the whole decompression period. The expired CO, was significantly higher with 70/30 than 30/70 during the compres sion phase of ACD-CPR. Beyond that no significant differences in the e xpire. CO2 levels was observed. In conclusion a reduction of the compr ession period to 30% during ACD-CPR reduced the cerebral circulation, the mean aortic and right atrial pressures with no effect on the myoca rdial blood flow of varying the compression-decompression cycle. (C) 1 998 Elsevier Science Ireland Ltd. All rights reserved.