title: Pharmacokinetics of levobupivacaine 0.5% after superficial or combined (deep and superficial) cervical plexus block in patients undergoing minimally invasive parathyroidectomy.
abstract: OBJECTIVE
  To evaluate the pharmacokinetic profile of 0.35 mL/kg of 0.5% levobupivacaine during superficial and combined (deep and superficial) cervical plexus block (CPB) in patients undergoing minimally invasive parathyroidectomy.
  
  
  METHODS
  Prospective randomized study.
  
  
  METHODS
  Operating theater of a university hospital.
  
  
  METHODS
  12 ASA physical status II and III patients (11 women and 1 man), scheduled for minimally invasive parathyroidectomy.
  
  
  METHODS
  Seven and 5 patients were randomly assigned to receive either superficial or combined CPB, respectively. The superficial CPB was performed with an injection of 0.35 mL/kg of 0.5% levobupivacaine subcutaneously along the posterior border of the sternocleidomastoid muscle and deeper on its medial surface. The combined CPB was initiated by the deep block at the C3 level vertebra by injecting 0.2 mL/kg of 0.5% levobupivacaine, followed by the superficial block with an injection of the remaining 0.15 mL/kg. After completion of the block, venous blood was sampled at the intervals of 5, 10, 15, 20, 30, 45, and 60 minutes.
  
  
  RESULTS
  Venous plasma concentrations were measured using gas chromatography-mass spectroscopy. Mean +/- SD of maximal concentrations of levobupivacaine was 0.58 +/- 0.41 mg/L in group superficial and 0.52 +/- 0.28 mg/L in group combined (P = 0.71). The median (range) time required to reach the maximal concentrations was 30 minutes (20-30 min) in group superficial and 20 minutes (15-30 min) in group combined (P = 0.45). The areas under the drug concentration/time curve (AUC(10-60)) were also similar in both groups. No signs of central nervous system or cardiovascular toxicity or other untoward events were observed in any patient.
  
  
  CONCLUSIONS
  With the given dose regimen, levobupivacaine plasma concentrations were within safe ranges.
authors.affiliation: Department of Anaesthesiology, Institute of Oncology, Zaloska 2, 1000 Ljubljana, Slovenia. Electronic address: tstopar@onko-i.si.
authors.forename: Tatjana Stopar
authors.initials: TS
authors.lastname: Pintaric
authors.affiliation: Institute of Forensic Medicine, Medical Faculty of Ljubljana, Korytkova 2, 1000 Ljubljana, Slovenia.
authors.forename: Gordana
authors.initials: G
authors.lastname: Kozelj
authors.affiliation: Institute of Pharmacology and Experimental Toxicology, Medical Faculty of Ljubljana, Korytkova 2, 1000 Ljubljana, Slovenia.
authors.forename: Lovro
authors.initials: L
authors.lastname: Stanovnik
authors.affiliation: Department of Anesthesia, Medical Faculty, University of Parma, Via Gramsci 14, 43100 Parma, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Casati
authors.affiliation: Department of Surgery, Institute of Oncology, Zaloska 2, 1000 Ljubljana, Slovenia.
authors.forename: Marko
authors.initials: M
authors.lastname: Hocevar
authors.affiliation: Department of Anaesthesiology and Intensive Therapy, Clinical Center Ljubljana, Zaloska 7, 1000 Ljubljana, Slovenia.
authors.forename: Vesna Novak
authors.initials: VN
authors.lastname: Jankovic