Comparison of pulmonary vascular permeability index PVPI and global ejection fraction GEF derived from jugular and femoral indicator injection using the PiCCO-2 device: A prospective observational study.

BACKGROUND: Transpulmonary thermodilution (TPTD) is used to derive cardiac output CO, global end-diastolic volume GEDV and extravascular lung water EVLW. To facilitate interpretation of these data, several ratios have been developed, including pulmonary vascular permeability index (defined as EVLW/(0.25*GEDV)) and global ejection fraction ((4*stroke volume)/GEDV). PVPI and GEF have been associated to the aetiology of pulmonary oedema and systolic cardiac function, respectively. Several studies demonstrated that the use of femoral venous access results in a marked overestimation of GEDV. This also falsely reduces PVPI and GEF. One of these studies suggested a correction formula for femoral venous access that markedly reduced the bias for GEDV. Consequently, the last PiCCO-algorithm requires information about the CVC, and correction for femoral access has been shown. However, two recent studies demonstrated inconsistencies of the last PiCCO algorithm using incorrected GEDV for PVPI, but corrected GEDV for GEF. Nevertheless, these studies were based on mathematical analyses of data displayed in a total of 15 patients equipped with only a femoral, but not with a jugular CVC. Therefore, this study compared PVPI_fem and GEF_fem derived from femoral TPTD to values derived from jugular indicator injection in 25 patients with both jugular and femoral CVCs. METHODS: 54 datasets in 25 patients were recorded. Each dataset consisted of three triplicate TPTDs using the jugular venous access as the gold standard and the femoral access with (PVPI_fem_cor) and without (PVPI_fem_uncor) information about the femoral indicator injection to evaluate, if correction for femoral GEDV pertains to PVPI_fem and GEF_fem. RESULTS: PVPI_fem_uncor was significantly lower than PVPI_jug (1.48±0.47 vs. 1.84±0.53; p<0.001). Similarly, PVPI_fem_cor was significantly lower than PVPI_jug (1.49±0.46 vs. 1.84±0.53; p<0.001). This is explained by the finding that PVPI_fem_uncor was not different to PVPI_fem_cor (1.48±0.47 vs. 1.49±0.46; n.s.). This clearly suggests that correction for femoral CVC does not pertain to PVPI. GEF_fem_uncor was significantly lower than GEF_jug (20.6±5.1% vs. 25.0±6.1%; p<0.001). By contrast, GEF_fem_cor was not different to GEF_jug (25.6±5.8% vs. 25.0±6.1%; n.s.). Furthermore, GEF_fem_cor was significantly higher than GEF_fem_uncor (25.6±5.8% vs. 20.6±5.1%; p<0.001). This finding emphasizes that an appropriate correction for femoral CVC is applied to GEF_fem_cor. The extent of the correction (25.5/20.6; 124%) for GEF and the relation of PVPI_jug/PVPI_fem_uncor (1.84/1.48; 124%) are in the same range as the ratio of GEDVI_fem_uncor/GEDVI_fem_cor (1056ml/m2/821mL/m2; 129%). This further emphasizes that GEF, but not PVPI is corrected in case of femoral indicator injection. CONCLUSIONS: Femoral indicator injection for TPTD results in significantly lower values for PVPI and GEF. While the last PiCCO algorithm appropriately corrects GEF, the correction is not applied to PVPI. Therefore, GEF-values can be used in case of femoral CVC, but PVPI-values are substantially underestimated.

Consistency of cardiac function index and global ejection fraction with global end-diastolic volume in patients with femoral central venous access for transpulmonary thermodilution: a prospective observational study.

Global ejection fraction (GEF) and cardiac function index (CFI) are transpulmonary thermodilution (TPTD)-derived indices of the systolic function. Their validity relies on an accurate determination of the global end-diastolic volume (GEDV). Due to an overestimation of GEDV using a femoral central venous catheter (CVC) a correction formula for indexed GEDV (GEDVI) has been implemented in the latest PiCCO™-algorithm. However, a recent study demonstrated that correction for femoral CVC does not pertain to pulmonary vascular permeability index PVPI, which is calculated of extravascular lung water EVLW and GEDV. Therefore, it was the aim of our study to evaluate, if GEF and CFI are corrected for femoral CVC. In ten adult ICU-patients with PiCCO™-monitoring, ten triplicate TPTDs were performed within 30 h. 95 complete data sets were analyzed, if a GEDV corrected for CVC site was applied to derive CFI and GEF. Therefore, we compared displayed values CFIdisplayed and GEFdisplayed to CFIcalculated and GEFcalculated, which were calculated from displayed GEDV, cardiac output and stroke volume. GEDVcalculated derived from division of GEDVI by predicted body surface area did not substantially differ from GEDVdisplayed (1448 ± 414 ml vs. 1447 ± 416 ml), which suggests a correction of GEDV for CVC site. However, CFIdisplayed was significantly lower than CFIcalculated (3.8 ± 1.6/min vs. 5.1 ± 1. 8/min: p < 0.001), suggesting that CFIdisplayed is based on an uncorrected GEDV. By contrast, GEFcalculated (23.1 ± 8.7 %) was not substantially different from GEFdisplayed (22.4 ± 8.6 %). Although GEDV and GEF are corrected for femoral CVC site, this does not apply to CFI. However, all indices derived from GEDV should be calculated consistently.

Pulmonary vascular permeability index and global end-diastolic volume: are the data consistent in patients with femoral venous access for transpulmonary thermodilution: a prospective observational study.

BACKGROUND: Transpulmonary thermodilution (TPTD) derived parameters are used to direct fluid management in ICU-patients. Extravascular lung water EVLW and its ratio to pulmonary blood volume (pulmonary vascular permeability index PVPI) have been associated with mortality. In single indicator TPTD pulmonary blood volume (PBV) is estimated to be 25% of global end-diastolic volume (GEDV). A recent study demonstrated marked overestimation of GEDV indexed to body-surface area (BSA; GEDVI) when using a femoral central venous catheter (CVC) for indicator injection due to the additional volume measured in the vena cava inferior. Therefore, a correction formula derived from femoral TPTD and biometric data has been suggested. Consequence, one of the commercially available TPTD-devices (PiCCO; Pulsion Medical Systems, Germany) requires information about CVC site. Correction of GEDVI for femoral CVC can be assumed. However, there is no data if correction also pertains to unindexed GEDV, which is used for calculation of PBV and PVPI. Therefore, we investigated, if also GEDV, PBV and PVPI are corrected by the new PiCCO-algorithm. METHODS: In this prospective study 110 triplicate TPTDs were performed within 30 hours in 11 adult ICU-patients with PiCCO-monitoring and femoral CVC. We analyzed if the femoral TPTD correction formula for GEDVI was also applied to correct GEDV. Furthermore, we compared PVPIdisplayed to PVPIcalculated which was calculated as EVLWdisplayed/(0.25*GEDVdisplayed). RESULTS: Multiplication of GEDVIdisplayed by BSA resulted in GEDVcalculated which was not significantly different to GEDVdisplayed (1459 ± 365 mL vs. 1459 ± 366 mL) suggesting that correction for femoral indicator injection also pertains to GEDVdisplayed. However, PVPIdisplayed was significantly lower than PVPIcalculated (1.64 ± 0.57 vs. 2.27 ± 0.72; p < 0.001). In addition to a bias of -0.64 ± 0.22 there was a percentage error of 22%. Application of the correction formula suggested for GEDVI to PVPIdisplayed reduced the bias of PVPIdisplayed compared to EVLW/PBV from -0.64 ± 0.22 to -0.10 ± 0.05 and the percentage error from 22% to 4%. CONCLUSIONS: Correction for femoral CVC in the PiCCO-device pertains to both GEDVIdisplayed and GEDVdisplayed, but not to PVPIdisplayed. To provide consistent information, PVPI should be calculated based on GEDVcorrected in case of femoral CVC.