CENTRAL VENOUS-PRESSURE, PULMONARY CAPILLARY WEDGE PRESSURE AND INTRATHORACIC BLOOD VOLUMES AS PRELOAD INDICATORS IN CARDIAC-SURGERY PATIENTS

Objective: Monitoring of cardiac preload is mainly performed by measur ement of central venous and pulmonary capillary wedge pressure in comb ination with assessment of cardiac output, applying the pulmonary arte rial thermal dilution technique. However, the filling pressures are ne gatively influenced by mechanical ventilation and the pulmonary artery catheter is criticized because of its inherent risks. Measurement of right atria, right ventricular, global end diastolic and intrathoracic blood volume index by arterial thermal dye dilution utilizing the COL D-system may represent an alternative. Methods: In 30 CABG patients wi th an uncomplicated postoperative course the mentioned parameters were measured i, 3, 6, 12 and 24 h postoperatively to prove their qualific ation as preload indicators: As patients received no inotropic support , changes of cardiac index and stroke volume index must correlate to c hanges of presumably preload indicating parameters. Results: When arte rial and pulmonary arterial thermal dilution were compared, no differe nces were found; the correlation coefficient being 0.96, the bias 0.16 l/min per m(2) (2.4%) and coefficients of variation did not exceed 7% . Changes of central venous pressure, capillary wedge pressure, right atrial end diastolic volume index and right ventricular end diastolic volume index did not correlate at all to changes of cardiac and stroke volume index (coefficients ranged from -0.01 to 0.28). In contrast, i ntrathoracic and global end diastolic blood volume indices with coeffi cients from 0.76 to 0.87, did show a good correlation to cardiac and s troke volume index. Conclusion: Central venous pressure, capillary wed ge pressure, right atrial and right ventricular end diastolic volumes are no suitable preload parameters in cardiac surgery intensive care, compared to intrathoracic and global end diastolic blood volumes. The latter show a higher clinical value and can be obtained by less invasi ve methods, as no pulmonary artery catheter is required. (C) 1998 Else vier Science B.V. All rights reserved.