Therapeutic optimization of atrioventricular delay in ICU-patients by non-invasive cardiac output measurements versus pulse contour analysis

Objectives: Especially in cardiosurgical patients (pts) with impaired cardiac function, optimization of temporary pacing algorithms as AV-delay (AVD) improves cardiac output and postoperative outcome. Impedance cardiography (ICG) is a non-invasive, accurate and cost-effective method for continous measuring of cardiac output (CO) and stroke volume (SV). The purpose of this study was to evaluate the ability of two ICG methods with different algorithms to determine optimal AV-delay (OAV) and to compare these methods with conventional invasive PICCO-measurements.

Methods: In 9 ICU pts (age 71.6±12.4yrs) with temporary pacing wires, OAV was determined by pulse contour analysis (PICCO, PULSION) and ICG (BioZ.com, GE Medical monitor (BZ) and AESCULON, Osypka Medical monitor (AE), using new algorithms). CO and SV were measured during DDD pacing at fixed rates with AVD varying from 50 to 270 ms, respectively intrinsic conduction, in 20-ms increments.

Results: Measured OAV showed a linear correlation between PICCO and ICG in both systems: BZ (r=0.89, p<0.0013) and AE (r=0.81, p<0.0075). The mean deviation in OAV between PICCO and ICG was±17.6 ms (BZ) and±18.6 ms (AE). Hemodynamic parameters (at OAV vs. worst AVD) improved decisively (mean CO +0.72 l/min, mean SV +7.28ml).

Conclusion: Our results demonstrate that inappropriate selection of AVD can compromise hemodynamic situation of ICU patients. Due to its non-invasive character and beat-to-beat measurement, ICG is an reliable and effective tool for tailoring AVD. Both systems – BZ and AE – offer valid OAV determinations in critical ill pts even on lower care wards.