title: Pupil diameter during postanesthetic recovery is not influenced by postoperative pain, but by the intraoperative opioid treatment.
abstract: OBJECTIVE
  To investigate whether pupil diameter (PD) measured during scotopic conditions is influenced by pain in conscious patients in the early postoperative period.
  
  
  METHODS
  Prospective, observational, cohort study.
  
  
  METHODS
  Single-center, postanesthesia care unit (PACU).
  
  
  METHODS
  Patients scheduled for a surgery during general anesthesia.
  
  
  METHODS
  Baseline PD was measured the day before surgery. Patients were observed on admission to the PACU, immediately after extubation, during the different steps of analgesic intervention (demand, relief, plus intermediate measures when relevant), and either at discharge or 3 hours after admission.
  
  
  METHODS
  PD, pain (numerical rating scale), and alertness (Observer's Assessment of Alertness/Sedation scale).
  
  
  RESULTS
  Of 103 patients enrolled, 80 required analgesia in the PACU and completed follow-up. Pain intensity evolved in line with expectations (temporary increase then relief), and alertness increased with time. PD increased from low mean values at admission to the PACU (40% of baseline) to a plateau throughout the rest of the study period (80% of baseline) and was not related to pain intensity. Multivariate analyses suggested that the factors influencing PD (or its value related to baseline) were time since extubation and the type of opioid (remifentanil, sufentanil, or sufentanil at high doses) administered during surgery.
  
  
  CONCLUSIONS
  Because of a residual effect of intraoperative opioids and a level of nociceptive stimulation lower than in surgical conditions, PD is not significantly influenced by early postoperative pain or pain relief.
authors.affiliation: CHU Clermont-Ferrand, Centre de Pharmacologie Clinique, F-63000 Clermont-Ferrand, France; Inserm, CIC1405, F-63000 Clermont-Ferrand, France; Inserm, U1107 "Neuro-Dol", F-63000 Clermont-Ferrand, France. Electronic address: cduale@chu-clermontferrand.fr.
authors.forename: Christian
authors.initials: C
authors.lastname: Dualé
authors.affiliation: CHU Clermont-Ferrand, Pôle Anesthésie-Réanimation, Hôpital Gabriel-Montpied, F-63000 Clermont-Ferrand, France.
authors.forename: Hugues
authors.initials: H
authors.lastname: Julien
authors.affiliation: CHU Clermont-Ferrand, Direction de la Recherche Clinique et des Innovations, F-63000 Clermont-Ferrand, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Pereira
authors.affiliation: CHU Clermont-Ferrand, Pôle Anesthésie-Réanimation, Hôpital Gabriel-Montpied, F-63000 Clermont-Ferrand, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Abbal
authors.affiliation: CHU Clermont-Ferrand, Pôle Anesthésie-Réanimation, Hôpital Gabriel-Montpied, F-63000 Clermont-Ferrand, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Baud
authors.affiliation: Inserm, U1107 "Neuro-Dol", F-63000 Clermont-Ferrand, France; CHU Clermont-Ferrand, Pôle Anesthésie-Réanimation, Hôpital Gabriel-Montpied, F-63000 Clermont-Ferrand, France; Univ Clermont1, F-63001 Clermont-Ferrand, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Schoeffler
mesh_terms: D000368:Aged; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000494:pharmacology*; D000762:Anesthesia Recovery Period; D000768:Anesthesia, General / Q000379:methods; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D010149:Postoperative Pain / Q000503:physiopathology*; D010880:Piperidines / Q000008:administration & dosage / Q000494:pharmacology; D011446:Prospective Studies; D011680:Pupil / Q000187:drug effects*; D000077208:Remifentanil; D017409:Sufentanil / Q000008:administration & dosage / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D010880:Piperidines; D017409:Sufentanil; D000077208:Remifentanil
keywords: Analgesia; General anesthesia; Pain, postoperative; Pupillometry