title: Feasibility and pharmacokinetics of caudal blockade in children and adolescents with 30-50 kg of body weight.
abstract: BACKGROUND
  Caudal blockade, although an important technique of pediatric regional anesthesia, is rarely used in children heavier than 30 kg. This reservation is due to anatomical concerns and lack of pharmacokinetic data. We therefore set out to evaluate, in pediatric patients weighing 30-50 kg, the feasibility of ultrasound-guided caudal blockade and the pharmacokinetics of caudally administered ropivacaine.
  
  
  METHODS
  Twenty consecutive children were included. General anesthesia was used to ensure a secured airway. For the caudal punctures, we applied the same clinical standards as in smaller children, administering ropivacaine 3.1 mg·ml-1for a volume of 1 ml·kg-1via ultrasound guidance. Pharmacokinetic analysis was based on total plasma ropivacaine levels and included maximum concentration (Cmax), time to Cmax(tmax), terminal elimination half-life, area under the concentration-time curve for the 4-h sampling period, apparent total body clearance, and apparent volume of distribution.
  
  
  RESULTS
  In all 19 cases of successful puncture, we identified the relevant anatomical structures (sacral cornua, sacral hiatus, dura mater) and verified correct administration of the local anesthetic by visualizing its cranial spread. Surgical blockade was successful in 18 of 20 cases (90%; one puncture was technically not possible and one child received intraoperatively 50 μg fentanyl). The pharmacokinetic profile of the administered ropivacaine 3.1 mg·ml-1indicated plasma levels within safe ranges in pediatric patients weighing 30-50 kg.
  
  
  CONCLUSIONS
  Based on our pharmacodynamic and pharmacokinetic results, we suggest that the body weight of 50 kg it is feasible to perform effective and safe caudal blockade in children up to 50 kg body weight.
authors.affiliation: Department of Anaesthesiology and General Intensive Care Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Maya
authors.initials: M
authors.lastname: Keplinger
authors.affiliation: Department of Anaesthesiology and General Intensive Care Medicine, Medical University of Vienna, Vienna, Austria. peter.marhofer@meduniwien.ac.at.
authors.forename: Peter
authors.initials: P
authors.lastname: Marhofer
authors.affiliation: Department of Anaesthesiology and General Intensive Care Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Klug
authors.affiliation: Clinical Institute of Laboratory Medicine, Clinical Institute of Laboratory Medicine, Forensic Toxicology Unit, Medical University of Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Reiter
authors.affiliation: Clinical Institute of Laboratory Medicine, Clinical Institute of Laboratory Medicine, Forensic Toxicology Unit, Medical University of Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Stimpfl
authors.affiliation: Department of Anaesthesiology and General Intensive Care Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Stephan C
authors.initials: SC
authors.lastname: Kettner
authors.affiliation: Medical University of Vienna, Vienna, Austria.
authors.forename: Lena
authors.initials: L
authors.lastname: Korf
authors.affiliation: Department of Clinical Pharmacology, Medical University of Vienna, Vienna, Austria.
authors.forename: Markus
authors.initials: M
authors.lastname: Zeitlinger
authors.affiliation: Department of Anaesthesiology and General Intensive Care Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Daniela
authors.initials: D
authors.lastname: Marhofer
authors.affiliation: Department of Anaesthesiology and General Intensive Care Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Lydia
authors.initials: L
authors.lastname: Triffterer
mesh_terms: D000577:Amides / Q000493:pharmacokinetics*; D000763:Anesthesia, Caudal / Q000379:methods*; D000779:Anesthetics, Local / Q000493:pharmacokinetics*; D001835:Body Weight; D002648:Child; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D008297:Male; D000077212:Ropivacaine; D018084:Ultrasonography, Interventional
chemical_list: D000577:Amides; D000779:Anesthetics, Local; D000077212:Ropivacaine
keywords: adolescent (D000293); anesthesia; caudal (D000763); child (D002648); pharmacokinetics (D010599); ropivacaine (C037663); utrasonography (Q000736)