title: Pupillary reflex measurement predicts insufficient analgesia before endotracheal suctioning in critically ill patients.
abstract: BACKGROUND
  This study aimed to evaluate the pupillary dilatation reflex (PDR) during a tetanic stimulation to predict insufficient analgesia before nociceptive stimulation in the intensive care unit (ICU).
  
  
  METHODS
  In this prospective non-interventional study in a surgical ICU of a university hospital, PDR was assessed during tetanic stimulation (of 10, 20 or 40 mA) immediately before 40 endotracheal suctionings in 34 deeply sedated patients. An insufficient analgesia during endotracheal suction was defined by an increase of ≥1 point on the Behavioral Pain Scale (BPS).
  
  
  RESULTS
  A total of 27 (68%) patients had insufficient analgesia. PDR with 10 mA, 20 mA and 40 mA stimulation was higher in patients with insufficient analgesia (P <0.01). The threshold values of the pupil diameter variation during a 10, 20 and 40 mA tetanic stimulation to predict insufficient analgesia during an endotracheal suctioning were 1, 5 and 13% respectively. The areas (95% confidence interval) under the receiver operating curve were 0.70 (0.54 to 0.85), 0.78 (0.61 to 0.91) and 0.85 (0.721 to 0.954) with 10, 20 and 40 mA tetanic stimulations respectively. A sensitivity analysis using the Richmond Agitation Sedation Scale (RASS) confirmed the results. The 40 mA stimulation was poorly tolerated.
  
  
  CONCLUSIONS
  In deeply sedated mechanically ventilated patients, a pupil diameter variation ≥5% during a 20 mA tetanic stimulation was highly predictable of insufficient analgesia during endotracheal suction. A 40 mA tetanic stimulation is painful and should not be used.
authors.forename: Jerome
authors.initials: J
authors.lastname: Paulus
authors.forename: Antoine
authors.initials: A
authors.lastname: Roquilly
authors.forename: Hélène
authors.initials: H
authors.lastname: Beloeil
authors.forename: Julien
authors.initials: J
authors.lastname: Théraud
authors.forename: Karim
authors.initials: K
authors.lastname: Asehnoune
authors.forename: Corinne
authors.initials: C
authors.lastname: Lejus
mesh_terms: D000328:Adult; D000368:Aged; D000698:Analgesia / Q000379:methods*; D016638:Critical Illness / Q000628:therapy; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010147:Pain Measurement / Q000379:methods*; D010812:Physical Stimulation / Q000379:methods; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012025:Reflex, Pupillary / Q000187:drug effects / Q000502:physiology*; D012121:Respiration, Artificial / Q000379:methods; D013396:Suction