Comparison of pleth variability index, transesophageal echocardiography, transthoracic echocardiography and pumonary artery catheter measurements to evaluate pantient volume status

Aim: Fluid and electrolyte imbalances are extremely common problems in the perioperative period. Intraoperative goal directed fluid therapy has been shown to reduce the mortality, duration of hospitalization and intensive care unit requirement. The goal directed fluid therapy is critical for the improvement of outcome of the management in the postoperative period. Several static and dynamic measurements are used to assess the intravascular volume status. Dynamic measurements are known to be more sensitive for predicting fluid responsiveness especially patients under mechanical ventilation whereas static measurements are known to be low predictive. In this study we aimed to identify which methods are more predictable to determine the intravascular volume status. Methods: Patients between 18-66 years of age, ASA 1-3, undergoing coronary artery bypass graft (CABG) and / or valvular surgery were enrolled in the study. Anesthesia was induced in all patients with similar agents and maintenance BIS index value was provided to be held between 40- 60. Patients were ventilated in volume control mode after intubation with standard settings. Body temperature was standardized with nasopharyngeal temperature probe to be held over 36 0C during operation. Basic hemodynamic data were recorded in three sessions; after anesthetic induction (t0), after raising both of the lower limbs 45 degrees (3 min by waiting) (t1) and after infusion of 250 ml of crystalloid (in 5 min) (t2). Additionally, central venous pressure (CVP) via pulmonary arterial catheter, pulmonary artery pressure (PAP), pulmonary capillary occlusion pressure (PCWP), systemic vascular resistance (SVR), cardiac output (CO), cardiac index (CI), Pleth Variability Index (PVI), left and right ventricular end-diastolic volumes (LVEDV, RVEDV) by transesophageal echocardiography (TEE) device and vena cava inferior diameter by transthoracic echocardiography (TTE) measurements were recorded simultaneously. After all measurements were taken surgery started. Volume responsiveness was defined as increase of CI more than 15% (responder :∆CI≥15%, non-responder: ∆CI <15%). Findings: In our study, 7 women (35%) and 13 men (65%), totally 20 patients were included. Patients' age ranged between 19 and 66 years, an average of 53.80 ± 10.74 years. Patients were divided into two groups; 5 patients (25%) as responder and remaining 15 patients as non-responder (75%). MAP, CVP, PAP, PCWP, SVR, CO, CI, PI, RVEDV, LVEDV, VCI measurements after passive leg raising were significantly higher (p<0.01) than after inception (p:0.001) and fluid administration (p:0.001). After fluid administration CVP, PAP, PCWP, SVR, CO, CI, PI, RVEDV, LVEDV, VCI measurements were significantly higher than the initiation (p:0.001; p<0.01).Initial PVI average were significantly higher (p<0.01) than the PVI averages after passive leg raising(p:0.001) and fluid administration (p:0.001).PVI average after fluid administration was significantly higher than after passive leg raising (p:0.015; p<0.05). Compared to baseline with after leg raising, rising percentages of MAP, CVP, PAP, PCWP, SVR, CO, CI, PI, RVEDV, LVEDV, VCI diameter were significantly higher compared to baseline with after fluid administiration (p.0.001; p<0.01). Compared to baseline with after leg raising, PVI decline percentages were significantly higher than compared to baseline with after fluid administiration. (p.0.007; p<0.01). ROC curves of PVI, VCI, RVEDV and LVEDV were analyzed for predicting fluid responsiveness. Only for PVI, the area under the ROC curve was significantly higher than 0.5 (p<0.01; p<0.05). The best cut-off point for PVI was found 19. Conclusion: We recommend frequent use of dynamic parameters such as PVI in the clinical routine, because they are easy to apply bedside, non-invasive and known to be more sensitive for predicting fluid responsiveness and effective for managing goal-directed fluid therapy. Sufficient amount of liquid can be passed through the central compartment with passive leg raising method which is not applied in daily practice. Therefore, we recommend the use of passive leg raising more frequently in clinical routine instead of fluid replacement which considered as first step therapy. Keywords: PVI, Passive Leg Raising, Goal Directed Fluid Therapy