title: The effect of injection speed on remifentanil-induced cough in children.
abstract: BACKGROUND
  Remifentanil sometimes elicits cough during induction of anesthesia, as with the use of other fentanyl congeners. We designed this study to investigate the incidence of remifentanil-induced cough (RIC) in children and to evaluate the effect of injection speed on RIC.
  
  
  METHODS
  One hundred twenty ASA physical status I-II patients, aged 3-12 yr, undergoing general anesthesia were enrolled in the study. Patients were randomly assigned to one of the three groups. Patients in Group R30 received remifentanil 1.5 µg/kg at a constant rate over 30 s. Patients in Group R45 received remifentanil 1.5 µg/kg over 45 s, and patients in Group R60 received remifentanil 1.5 µg/kg over 60 s, respectively. Episodes of cough were recorded and graded as mild (1-2), moderate (3-4), or severe (5 or more). Mean arterial pressure (MAP), heart rate (HR), and SpO2 were recorded on arrival in the operating room (baseline) and 1 min after remifentanil infusion.
  
  
  RESULTS
  The incidence of RIC was 33.3% in Group R30 (13 of 39 patients), 17.9% in Group R45 (7 of 39 patients), and 5.0% in Group R60 (2 of 40 patients). Patients in Group R60 had a significantly lower incidence of RIC than those in Group R30 (P = 0.001). The MAP, HR, and SpO2 values were not significantly different between groups.
  
  
  CONCLUSIONS
  When intravenous remifentanil 1.5 µg/kg was administered in pediatric patients, the incidence of RIC decreased from 33 to 5% by increasing the injection time from 30 to 60 s. Remifentanil should be administered slowly over 60 s in children to suppress cough during anesthesia induction.
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Yoo
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Bong-Ki
authors.initials: BK
authors.lastname: Moon
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Baek-Hyun
authors.initials: BH
authors.lastname: Yoon
authors.affiliation: Department of Anesthesiology and Pain Medicine, Ajou University School of Medicine, Suwon, Korea.
authors.forename: Jong-Yeop
authors.initials: JY
authors.lastname: Kim
keywords: Anesthesia; Cough; Injection speed; Remifentanil