title: Early pharmacokinetic of ropivacaine without epinephrine after injection into the psoas compartment.
abstract: BACKGROUND
  Large amounts of local anaesthetics (LA) are used during psoas compartment block (PCB), especially if combined with sciatic nerve block. Data regarding early pharmacokinetics of ropivacaine for PCB are lacking, notably when a vasoconstrictive agent has not been added.
  
  
  METHODS
  PCB was established in 11 patients using 150 mg ropivacaine without epinephrine. Free and total arterial plasma concentrations of ropivacaine were measured at nine time points during the following 30 min. Also total protein, albumin, and α1-acid glycoprotein concentrations were analysed.
  
  
  RESULTS
  Ropivacaine plasma concentrations were found in all patients within 30 s after injections. Maximum measured plasma concentrations were measured in all but two patients within the first 10 min. One patient experienced partial intravascular injection. Plasma concentrations showed wide inter-individual variability. Ranges of maximum measured plasma concentrations of total and free ropivacaine were 422-3905 and 5-186 ng ml(-1), respectively. The Pearson correlation between total and free concentrations was 0.96. No obvious relationship between concentrations of different plasma proteins (total protein, albumin, α1-acid glycoprotein) and ropivacaine concentrations was found. Maximal 5% of the measured ropivacaine was unbound. All blocks were successful and no signs of toxicity were observed.
  
  
  CONCLUSIONS
  Maximum measured plasma concentrations of ropivacaine after PCB must be expected within 10 min. Although plasma concentrations stayed below toxic thresholds, our study demonstrates the risk of this regional anaesthesia technique.
  
  
  BACKGROUND
  The clinical study was not registered because enrolment of study patients occurred in 2006.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, D-01307 Dresden, Germany matthias.huebler@uniklinikum-dresden.de.
authors.forename: M
authors.initials: M
authors.lastname: Hübler
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, D-01307 Dresden, Germany.
authors.forename: M C
authors.initials: MC
authors.lastname: Planitz
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstr. 74, D-01307 Dresden, Germany.
authors.forename: O
authors.initials: O
authors.lastname: Vicent
mesh_terms: D000368:Aged; D000577:Amides / Q000097:blood / Q000493:pharmacokinetics*; D000779:Anesthetics, Local / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D004837:Epinephrine / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D016658:Psoas Muscles / Q000187:drug effects / Q000294:innervation; D000077212:Ropivacaine
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine; D004837:Epinephrine
keywords: anaesthetics local, ropivacaine; nerve block; pharmacokinetics, ropivacaine; toxicity, local anaesthetics