Original contributionCapnography enhances surveillance of respiratory events during procedural sedation: a meta-analysis☆,☆☆
Introduction
The use of procedural sedation and analgesia (PSA) and patient-controlled analgesia (PCA) has increased in frequency and scope [1]. More clinicians without anesthesia training are performing and monitoring these activities. Although end-tidal carbon dioxide (ETCO2) monitoring is routinely used during general anesthesia to monitor ventilatory status, this is not the case for PSA and PCA [2], where pulse oximetry and visual inspection represent the standard of care [3]. Pulse oximetry does not provide early detection of hypoventilation, apnea, or airway obstruction [4]. Vargo et al reported a study of 49 patients receiving sedation during upper gastrointestinal (GI) endoscopy in which 54 episodes of apnea were detected in 28 patients by capnography whereas pulse oximetry detected only 27 episodes (50%); none of these events was detected by visual assessment [4]. Some reports question the reported incidence rates of respiratory depression/complications associated with PSA (reported incidence of complications varied between institutions by a factor of 15) and PCA [5], [6], suggesting higher rates than the averages typically reported in the literature.
The Joint Commission on Accreditation of Healthcare Organizations (now the Joint Commission) revised the standards for monitoring patient sedation in 2001 [7]. Specific reference to moderate and deep sedation was included in the care and treatment standards. The standards state that qualified personnel should monitor patients receiving sedation during the procedure and recovery phase, and require that heart rate and oxygenation be monitored continuously by pulse oximetry. Adequacy of ventilation and respiratory frequency must be monitored continuously, and the clinician must be prepared to manage a level of sedation that is deeper than intended.
The aim of this analysis was to determine if capnography added to standard monitoring, including pulse oximetry, allowed for identification of significantly more respiratory complications during procedural sedation in adults compared with standard monitoring without capnography.
Section snippets
Data sources and searches
This meta-analysis followed the PRISMA (“Preferred reporting items for systematic reviews and meta-analyses”) guidelines for reporting analyses [8]. The following databases were searched from 1995-2009 for relevant studies: PubMed (free-access database of the National Library of Medicine, Bethesda, MD, USA); CINAHL (Cumulative Index to Nursing and Allied Health Literature, Ebsco Publishing Co., Glendale, CA, USA); and the Cochrane Library (John Wiley & Sons, Ltd., Hoboken, NJ, USA),
Brief descriptions of the 5 selected studies
Miner et al (2002) [1]: This prospective study of 74 adults receiving procedural sedation sought to evaluate the usefulness of ETCO2 monitoring to detect respiratory depression during PSA in the Emergency Department. Investigators compared ETCO2 measurements with the Observer's Assessment of Alertness/Sedation (OAA/S) scale and the development of respiratory depression and found no significant correlation between ETCO2 and the OAA/S scale. Respiratory depression was defined as ETCO2 > 50 mmHg,
Discussion
The pooled findings of this secondary analysis show that the addition of capnography to patient monitoring during procedural sedation significantly increased the detection of adverse respiratory events. If there is an easy, safe, and inexpensive way to enhance their detection, it is logical to take advantage of that method. This would be especially helpful in situations where the procedure becomes unexpectedly complex and demanding of attention, if the patient is covered in a way that makes
Acknowledgment
The authors thank Ms. Lee Vucovich, MS, MLS, for her assistance with searching the electronic databases used in this study.
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Funding: No support was received to conduct this project.
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Disclosure: Drs. Epps and Waugh have consulted for Oridian Capnography, Inc., Needham, MA, USA, a manufacturer of capnography devices.