AIMSThe aim of this study was to develop a pharmacokinetic model in order to characterize the free and total ropivacaine concentrations after transversus abdominis plane block in a population of patients undergoing liver resection surgery. In particular, we evaluated the impact of the size of liver resection on ropivacaine pharmacokinetics.
METHODSThis work is based on a single-centre, double-blinded, randomized, placebocontrolled study. Among the 39 patients included, 19 patients were randomized to the ropivacaine group. The free and total ropivacaine concentrations were measured in nine or 10 blood samples per patient. A pharmacokinetic model was built using a nonlinear mixed-effect modelling approach.
RESULTSThe free ropivacaine concentrations remained under the previously published toxic threshold. A one-compartment model, including protein binding site with a first-order absorption, best described the data. The protein binding site concentration was considered as a latent variable. Bodyweight, the number of resected liver segments and postoperative fibrinogen evolution were, respectively, included in the calculation of the volume of distribution, clearance and binding site production rate. The resection of three or more liver segments was associated with a 53% decrease in the free ropivacaine clearance.
CONCLUSIONSAlthough large liver resections were associated with lower free ropivacaine clearance, the ropivacaine pharmacokinetic profile remained within the safe range after this type of surgery.
WHAT THIS STUDY ADDS• The free ropivacaine fraction is low after liver resection surgery (<2%).• The size of the liver resection affects the free ropivacaine clearance.• The pharmacokinetics of free and total ropivacaine could be analysed effectively even without α 1 -acid glycoprotein measurements.
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• Ropivacaine is highly bound to plasma proteins (α 1 -acid glycoprotein).• Ropivacaine is mainly metabolized by the liver.• Liver resection affects the protein binding and metabolism of ropivacaine.
Objective The aim of this study was to investigate the feasibility and future clinical applications of near-infrared (NIR) fluorescence imaging to guide liver resection surgery for metastatic cancer to improve resection margins. Summary Background Data A subset of patients with metastatic hepatic tumors can be cured by surgery. The degree of long-term and disease-free survival is related to the quality of surgery, with the best resection defined as "R0" (complete removal of all tumor cells, as evidenced by microscopic examination of the margins). Although intraoperative ultrasonography can evaluate the surgical margins, surgeons need a new tool to perfect the surgical outcome. Methods A preliminary study was performed on 3 patients. We used NIR imaging postoperatively "ex vivo" on the resected liver tissue. The liver tumors were preoperatively labelled by intravenously injecting the patient with indocyanine green (ICG), a NIR fluorescent agent (24 hours before surgery, 0.25 mg/kg). Fluorescent images were obtained using a miniaturized fluorescence imaging system (FluoStic, Fluoptics, Grenoble, France). Results After liver resection, the surgical specimens from each patient were sliced into 10-mm sections in the operating room and analyzed with the FluoStic. All metastatic tumors presented rim-type fluorescence. Two specimens had incomplete rim fluorescence. The pathologist confirmed the presence of R1 margins (microscopic residual resection), even though the ultrasonographic analysis indicated that the result was R0. Conclusions Surgical liver resection guided by NIR fluorescence can help detect potentially uncertain anatomical areas that may be missed by preoperative imaging and by ultrasonography during surgery. These preliminary results will need to be confirmed in a larger prospective patient series.
In patients'≥75 years, strategies of anaesthesia optimisation are not in accordance with eligible guidelines. Implementation of these techniques varies independently of factors related to the patient or the type of surgery and may be dependent on the generated constraints.
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