Assessment of fluid-responsiveness parameters for off-pump coronary artery bypass surgery: a comparison among LiDCO, transesophageal echochardiography, and pulmonary artery catheter.

OBJECTIVE: To verify the reliability of different markers of fluid-responsiveness during off-pump cardiac surgery (OPCAB). DESIGN: A clinical prospective, nonblinded, nonrandomized study. SETTING: A community hospital. PARTICIPANTS: Nineteen patients. INTERVENTIONS: Pulmonary artery catheter (PAC), LiDCO (LiDCO, London, UK), and transesophageal echocardiography (TEE) parameters were measured before (t0) and after (t1) a fluid challenge was performed 20 minutes after induction of anesthesia, but before sternotomy and without inotropic infusion. A Student t test and Spearman test were performed for statistical analysis. MEASUREMENTS AND MAIN RESULTS: According to the variation of cardiac index after the fluid challenge (DeltaCI%), 2 groups of patients were identified: the responders (Re, DeltaCI% > 15%) and the nonresponders (nRe). Mean pulse pressure variation (PPV) and mean stroke volume variation (SVV) before the fluid challenge (t0) were significantly different between the 2 groups. No significant differences were shown in systolic pressure variation (SPV), left ventricular end-diastolic area, left ventricular end-diastolic volume, and peak changes of aortic flow (DeltaVAo). A statistically significant correlation was observed between DeltaCI% and PPV (R = 0.793), DeltaCI% and SVV (R = 0.809), and DeltaCI% and SPV (R = 0.766). No correlation with central venous pressure and pulmonary capillary wedge pressure was found. CONCLUSIONS: Dynamic parameters of fluid responsiveness by LiDCO are highly sensitive for assessment of intravascular volume status during OPCAB surgery. In contrast, even if static parameters by TEE reflect changes in ventricular diastolic volume, they are poor indicators of fluid responsiveness. Surprisingly, no significant correlation between DeltaVAo (TEE) and DeltaCI% was found.

[What's the best assessment of preload after cardiac surgery?]. / La valutazione del precarico post-intervento cardiochirurgico: quale monitoraggio?

OBJECTIVE: The assessment of the role of transesophageal echocardiography and invasive tests with pulmonary modified catheter to monitor the preload indexes in patients in intensive-care-unit after cardiac coronary surgery. MATERIALS AND METHODS: Between January and December 2004 24 patients (14 male, 10 female) with coronary artery disease were prospectively enrolled for preload assessment during off-pump myocardial revascularization. Pulmonary Capillary Wedge Pressure (PCWP), Left Ventricular End Diastolic Indexed Area (LVEDAI), delta Aortic Velocity (deltaVAo), Right Ventricular End Diastolic Volume (RVEDVI) as preload indexes were evaluated. Transesophageal echocardiography and pulmonary modified catheter monitoring were performed during the preoperative period at T1 and after fluid infusion (T2). Patients were considered Responders (R) or No Responders (NR) if the Stroke Volume Index increase at T2 was >20% with respect to T1. RESULTS: Mean T1 PCWP was similar in both groups (12.8+/-2.2 in R vs. 11.4+/-3 mmHg in NR; p=NS) and mean increase of PCWP at T2 was similar in both groups (1.5+/-0.3% in R vs. 1.2+/-3% in NR; p=NS). Mean T1 RVEDVI was similar in both groups (97.33+/-34 in R vs. 101+/-21 ml/m2 in NR; p=NS); T2 RVEDVI was similar in R and NR Groups (122.11+/-49 vs. 138.54+/-30 ml/m2; p=NS); mean T1 and T2 LVEDAI was similar in R and NR (11.2+/-3.5 vs. 10.2+/-2.3 at T1 and 14.04+/-3.35 vs. 14.67+/-2.1 cm2/m2 at T2 respectively; p=NS). Higher mean value of T1 deltaVAo (20+/-7% in R vs. 10+/-2% in NR; p=0.006) were recorded while similar mean value of T2 deltaVAo were observed (11+/-3% in R vs. 5+/-2% in NR; p=0.743). Correlation index between T1 and T2 deltaVAo (R=0.82) in R was significant (p=0.0002), while correlation index between T1 and T2 deltaVAo (R=0.11) in NR was not significant. CONCLUSIONS: Our study showed in patients soon after coronary cardiac surgery deltaVAo is the only predictor of "fluid responsiveness" and of ventricular compliance.