Laparoscopic Infrahepatic Inferior Vena Cava Clamping During Liver Resection — a Feasibility Study

Intraoperativehemorrhage is a major predictor of perioperative outcomes after hepatectomy. Infrahepatic inferior vena cava (IVC) clamping has already been proven as a safe and effective technique to reduce intraoperative blood loss (BL) in open liver resection (OLR).1 However, its effectiveness and safety in laparoscopic liver resection (LLR) remains unclear. Therefore, it was the objective of this study to evaluate the perioperative outcomes and feasibility of IVCclamping in LLR at a European tertiary-center.


Introduction
Intraoperativehemorrhage is a major predictor of perioperative outcomes after hepatectomy. Infrahepatic inferior vena cava (IVC) clamping has already been proven as a safe and effective technique to reduce intraoperative blood loss (BL) in open liver resection (OLR). 1 However, its effectiveness and safety in laparoscopic liver resection (LLR) remains unclear. Therefore, it was the objective of this study to evaluate the perioperative outcomes and feasibility of IVCclamping in LLR at a European tertiary-center.

Methods
Patients undergoing LLR with intraoperative IVC-clamping at our department were identified from a prospective database (August 2020-August 2021).
To gain access to the IVC, the liver was lifted up, and the IVC was dissected right below the hepatoduodenal ligament above the level of the left renal vein. Once dissected, the IVC was clamped (Fig. 1a). Initially, the IVC was clamped partially to confirm the patients' hemodynamic stability in consultation with the anesthesiologist. If tolerated, the clamp was pushed forward and closed consecutively. Parenchymal transection was carried out under low central venous pressure (CVP) and (i) CO 2 pneumoperitoneum of at least 15 up to 18 mmHg, (ii) reversed Trendelenburg position, and (iii) intermittent Pringle maneuvers (max. 15 min of ischemia followed by 5 min of reperfusion).
Demographics and outcomes were analyzed using descriptive statistics.

Results
Ten patients underwent LLR with IVC-clamping (Table 1). In all patients, IVC-clamping was established without any complication. Intraoperative hemodynamic parameters are summarized in Fig. 1b. Mean CVP during resection was 6.7 mmHg (s.d.: ± 6.1 mmHg). Temporary hemodynamic instability (positive shock-index) occurred in five patients and ceased spontaneously. MAP trajectory in Fig. 1b (F) indicates that MAP was never below 60 mmHg. Median operating time was 258 min (interquartile range (IQR), 212-302 min) and median BL during transection was 320 mL (IQR, 170-740 mL). In three patients, minor air embolisms were detected, but without any clinical consequences and were treated by intermittent hyperventilation. Functional recovery was achieved after a median of 4 days (IQR, 2-4 days). Median length of stay was 6 days (IQR, 5-7 days). Two patients developed clinically relevant complications (Clavien-Dindo ≥ III), both presented with post-hepatectomy bile leakage and needed to be readmitted. No mortality occurred within 90 days after surgery.

Discussion
The second international consensus conference for LLR held in Morioka (2014) recommended a low CVP during LLR to achieve a reduction of BL. A possible reduction of BL with Patrick Téoule and Niccolo Schmidt contributed equally to this work.  low CVP by restrictive fluid administration comes at the cost of a higher risk of hemodynamic instability in case of major BL. 1 A study on OLR revealed that IVC-clamping could be used as a potential alternative to conservative CVP-lowering to reduce BL. 1 Despite this proven effectiveness, IVCclamping in LLR has been poorly explored and not been performed routinely. Recently, the evidence of LLR with IVC-clamping has only been reported in one retrospective study. 3 However, within this study, authors neither defined the time period of reported morbidity nor provided data on CCI or functional recovery. The overall BL in our study is higher than expected, compared to other studies. This could be biased by our small study group or could be explained by the complexity of the performed operations (median IWATE score of eight). Furthermore, the presence of cirrhosis in 40% of patients might have contributed to the slightly higher BL. Within a RCT on the impact of IVC-clamping on BL during OLR, a significantly higher rate of post-operative pulmonary embolism (PPE) was observed. 1 Therefore, uncertainty about the impact of IVC-clamping during LLR exists. However, a recent meta-analysis confirmed that IVCclamping is not associated with increased incidence of PPE in OLR. 4 In this study, we did not observe any case of PPE. Compared to other studies performing LLR without IVCclamping, our results showed no potential risk or increased morbidity and mortality. 5,6 The present study provides initial data on the feasibility and safety of IVC-clamping during LLR and justify future