title: Characteristics of and Predictors for Apnea and Clinical Interventions During Procedural Sedation.
abstract: We describe the characteristics of and predictors for apnea and clinical interventions during emergency department (ED) procedural sedation.
  
  
  
  High-resolution data were collected prospectively, using a convenience sample of ED patients undergoing propofol or ketofol sedation. End tidal CO2(etco2), respiratory rate, pulse rate, and SpO2were electronically recorded in 1-second intervals. Procedure times, drug delivery, and interventions were electronically annotated. Kaplan-Meier curves were used to describe the onset of clinical interventions as a function of sedation time. The onset of apnea (15 consecutive seconds with carbon dioxide ≤10 mm Hg) and clinical interventions were estimated with a series of Cox proportional hazards survival models, with time to first apnea or clinical intervention as the dependent variable. Finally, we tested the association between apnea and clinical intervention.
  
  
  
  Three hundred twelve patients were analyzed (53% male patients). Apnea was preceded by etco2less than 30 mm Hg or greater than 50 mm Hg at 30, 60, and 90 seconds before its onset. Clinical interventions were predicted by apnea, SpO2, and propofol use. Increasing age predicted both apnea and interventions. Apnea was not predicted by respiratory rate or SpO2. Apnea occurred in half of the patients and clinical interventions in a quarter of them. Clinical intervention was not predicted by abnormal respiratory rate or abnormal etco2level. The majority of clinical interventions (85%) were minor, with no cases of assisted ventilation, intubation, or complications.
  
  
  
  Alterations in etco2predicted apnea along a specific time course. Alterations in SpO2, apnea, and propofol use predicted clinical interventions. Increasing age predicted both apnea and clinical intervention.
authors.affiliation: Division of Emergency Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA. Electronic address: baruch.krauss@childrens.harvard.edu.
authors.forename: Baruch S
authors.initials: BS
authors.lastname: Krauss
authors.affiliation: University of British Columbia Department of Emergency Medicine, Lions Gate Hospital, North Vancouver, British Columbia, Canada.
authors.forename: Gary
authors.initials: G
authors.lastname: Andolfatto
authors.affiliation: University of Massachusetts, Boston, MA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Krauss
authors.affiliation: Institute for Medical Engineering and Science and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Mieloszyk
authors.affiliation: Division of Emergency Medicine, Boston Children's Hospital, Department of Pediatrics, Harvard Medical School, Boston, MA.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Monuteaux
mesh_terms: D000328:Adult; D000368:Aged; D001049:Apnea / Q000139:chemically induced*; D019296:Capnography; D016292:Procedural Sedation / Q000009:adverse effects* / Q000379:methods; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006993:Hypnotics and Sedatives / Q000009:adverse effects; D007649:Ketamine / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000009:adverse effects; D016016:Proportional Hazards Models; D056152:Respiratory Rate / Q000187:drug effects; D012307:Risk Factors; D055815:Young Adult
chemical_list: D006993:Hypnotics and Sedatives; D007649:Ketamine; D015742:Propofol