Conscious sedation in the emergency department: the value of capnography and pulse oximetry

Ann Emerg Med. 1992 May;21(5):551-5. doi: 10.1016/s0196-0644(05)82523-5.


Study objective: The purpose of this observational study was to describe the use of nasal capnography and pulse oximetry in monitoring heavily sedated emergency department patients.

Design: Prospective, nonblinded, nonrandomized, noncontrolled clinical trial.

Setting: The study was conducted in a tertiary-care hospital with 36,000 annual ED visits.

Type of participants: Twenty-seven patients requiring sedation with benzodiazepines and/or narcotics for painful procedures.

Interventions: The ventilatory status of each patient was monitored with a capnometer by nasal cannula as well as a pulse oximeter before, during, and after administration of the sedative agents.

Measurements: Vital signs, nasal end-tidal CO2 (PETCO2) measurements, and oxygen saturation were measured at baseline, during the procedure, and for a two-hour observation period after the procedure.

Main results: The average PETCO2 increased from 35.9 to 42.1 mm Hg during the procedure while the oxygen saturation dropped from an average of 98% to 94.3%. One patient developed clinically significant apnea after the procedure that was picked up by the apnea alarm, and eight additional patients developed clinically silent hypoxemia and increased PETCO2 during the procedure.

Conclusion: The use of pulse oximetry is recommended for the detection of unrecognized hypoxemia during conscious sedation. Capnography by nasal cannula appears to be a useful modality in monitoring during conscious sedation, but further research and clinical experience are required before routine use can be recommended.

Publication types

  • Clinical Trial

MeSH terms

  • Adolescent
  • Adult
  • Benzodiazepines / therapeutic use
  • Carbon Dioxide / analysis*
  • Conscious Sedation*
  • Female
  • Humans
  • Hypoxia / diagnosis
  • Male
  • Middle Aged
  • Minor Surgical Procedures
  • Monitoring, Physiologic / methods
  • Narcotics / therapeutic use
  • Oximetry*
  • Prospective Studies
  • Respiration*


  • Narcotics
  • Benzodiazepines
  • Carbon Dioxide