title: Effects of local anesthetic on the time between analgesic boluses and the duration of labor in patient-controlled epidural analgesia: prospective study of two ultra-low dose regimens of ropivacaine and sufentanil.
abstract: BACKGROUND
  Patient-controlled epidural analgesia with low concentrations of anesthetics is effective in reducing labor pain. The aim of this study was to assess and compare two ultra-low dose regimens of ropivacaine and sufentanil (0.1% ropivacaine plus 0.5 μg.ml-1 sufentanil vs. 0.06% ropivacaine plus 0.5 μg.ml-1 sufentanil) on the intervals between boluses and the duration of labor.
  
  
  METHODS
  In this non-randomized prospective study, conducted between January and July 2010, two groups of parturients received patient-controlled epidural analgesia: Group I (n = 58; 1 mg.ml-1 ropivacaine + 0.5 μg.ml-1 sufentanil) and Group II (n = 57; 0.6 mg.ml-1 ropivacaine + 0.5 μg.ml-1 sufentanil). Rescue doses of ropivacaine at the concentration of the assigned group without sufentanil were administered as necessary. Pain, local anesthetic requirements, neuraxial blockade characteristics, labor and neonatal outcomes, and maternal satisfaction were recorded.
  
  
  RESULTS
  The ropivacaine dose was greater in Group I (9.5 [7.7-12.7] mg.h-1 vs. 6.1 [5.1-9.8 mg.h-1], p < 0.001). A time increase between each bolus was observed in Group I (beta = 32.61 min, 95% CI [25.39; 39.82], p < 0.001), whereas a time decrease was observed in Group II (beta = -1.40 min, 95% CI [-2.44; -0.36], p = 0.009). The duration of the second stage of labor in Group I was significantly longer than that in Group II (78 min vs. 65 min, p < 0.001).
  
  
  CONCLUSIONS
  Parturients receiving 0.06% ropivacaine exhibited less evidence of cumulative effects and exhibited faster second stage progression than those who received 0.1% ropivacaine.
authors: Departamento de Anestesiologia. Maternidade Alfredo da Costa. Lisboa. Portugal.
authors: José Manuel
authors: JM
authors: Costa-Martins
authors: Cláudia Camila
authors: CC
authors: Dias
authors: Marco
authors: M
authors: Pereira
authors: Jorge
authors: J
authors: Tavares
mesh_terms: D000328:Adult; D000577:Amides / Q000008:administration & dosage*; D016058:Analgesia, Patient-Controlled; D000700:Analgesics / Q000008:administration & dosage*; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D000772:Anesthesia, Local; D000773:Anesthesia, Obstetrical; D000779:Anesthetics, Local / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007743:Labor, Obstetric; D011247:Pregnancy; D011446:Prospective Studies; D000077212:Ropivacaine; D017409:Sufentanil / Q000008:administration & dosage*; D013997:Time Factors
chemical_list: D000577:Amides; D000700:Analgesics; D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D000077212:Ropivacaine; D017409:Sufentanil