Does Inferior-Vena-Cava Collapsibility Correlate with Fluid Regimen and Outcome in Patients Undergoing Liver Resection?

Aim: We retrospectively investigated whether inferior-vena-cava diameter variations due to mechanical ventilation, correlates with fluid regimen and outcome in hepatic resection. Methods: We analyzed data from 91 cases of liver resection during which inferior vena cava collapsibility was measured in duplicate, before and after the resection phase of the operation (IVCI1 and IVCI2). IVCI was calculated according to the following formula: [IVCDmax-IVCDmin]/[0.5 × (IVCDmax+IVCDmin)], where IVCDmax and IVCDmin stand for the maximal and minimal IVCD within one a respiratory cycle. IVCI variation (ΔIVCI) was defined as: (IVCI pre-resection-IVCI post-resection)/IVCI pre-resection. Fluid management focused to maintain CVP <6 mmHg during the parenchymal dissection in an effort to reduce the backflow bleeding and limit the blood loss. Therefore, fluid administration included a volume input 3-5 ml/kg/h of crystalloid solutions from the induction of anesthesia until parenchymal dissection was concluded. Additional fluid administration was at the judgment of the anesthesiologist. Then we searched for any correlation between IVCI and other hemodynamic parameters, fluid regimen administration and the post-operative outcome. Results: Among 91 patients enrolled in the study, 57 (63%) were male and 34 (37%) female aged from 34 to 85 years (median 62 years). The median ASA was 2 (range 1-3). The median operation time was 374 min (range 150-720). Liver transaction was accomplished employing the Pringle maneuver and the median total liver ischemic time was 82 min (range 9-182). After liver resection ending many variables differed significantly from starting values: IVCI from 0.26 ± 0.21 to 0.18 ± 0.16 (p<0.001); HR from 68 ± 14 to 78 ± 13 bpm (p<0.001); CI from 2.6 ± 0.7 to 3.0 ± 0.8 L/min/m2 (p<0.001). All BGA values changed significantly (p<0.001). Serum lactate concentration showed a significant increase during the parenchymal dissection changing from 0.95 ± 0.5 to 4.1 ± 2.0 mmol/L (p<0.001). Serum hemoglobin lowered from 11.3 ± 1.7 g/dl to 9.8 ± 1.8 g/dl (p<0.001). In contrast, CVP and SVV did not change significantly. Both IVCI1 and IVC2 showed a weak correlation with CI (r=-0.166 and r=-0.087), CVP (r=-0.049 and r=-0.083) and SVV (r=0.138 and r=0.121). According to postoperative outcome patients were divided in two groups: Group 1 (complicated) and Group 2 (non-complicated). The IVCI resulted not significantly different between two groups (0.12 ± 0.11 vs 0.16 ± 0.13; p=0.105) which were homogeneous for global fluid regimen (7.25 ± 2.63 ml/kg/h vs 7.98 ± 2.93 ml/kg/h; p=0.341). Conclusions: Although retrospectively, it seems clear that, during hepatic resection, IVCI is not sensible to fluid administration and is not correlated with postoperative outcome.