Yesterday’s luxury – today’s necessity: end-tidal CO2 monitoring during conscious sedation

Abstract

The Canadian Journal of Anesthesia recently published the Canadian Anesthesiologists’ Society (CAS) ‘‘Guidelines to the Practice of Anesthesia – Revised Edition 2012’’ (hereafter referred to as the 2012 Guidelines), which included an important amendment in the section regarding required monitors – CO2 monitoring (capnography) during conscious sedation. While a few practitioners may have been fortunate to use this valuable monitor for deeper levels of sedation during monitored anesthesia care, most others probably have not (or have chosen not to use it). As the practice of CO2 monitoring is now expected to change, at least for anesthesiologists, some practitioners may question the rationale for implementing this amendment. Originally introduced in 1975, the CAS Guidelines are reviewed annually by the CAS Standards Committee, and changes are advanced for approval by the Board of Directors of the CAS. Many factors are considered when changes to the CAS Guidelines are contemplated, including a review of the relevant peer-reviewed literature and pertinent practice guidelines in other jurisdictions, especially those in North America. A lengthy discussion amongst the members of the Standards Committee often forms a necessary part of this decision-making process, referred to as ‘‘expert consensus’’. While the value of rigorous ‘‘evidence-based guidelines’’ is recognized, the costs to develop such formal documents are considered beyond the reach of the CAS. In perspective, the American Society of Anesthesiologists (ASA) estimates the costs to create evidencebased guidelines to be in the order of approximately $2.5 million per document (Dr. J. Apfelbaum, personal communication), which is roughly equal to the entire annual budget of the CAS. Over the past few years, there have been a number of small modifications to the body of the CAS Guidelines as well as the addition of two appendices (i.e., two position papers, one on anesthesia assistants and another on sedation). The 2012 Guidelines include an important addition to the section that defines ‘‘Patient Monitoring’’ standards. Monitoring equipment is classified as ‘‘Required...must be in continuous use throughout the administration of all anesthetics’’ or ‘‘Exclusively available’’, or ‘‘Immediately available’’. The new classification stipulates that ‘‘Capnography for general anesthesia and sedation (RSS 4-6)’’ is ‘‘required’’ monitoring. The modified Ramsey sedation scale (RSS) is outlined in Appendix 6 of the 2012 Guidelines, ‘‘Position Paper on Procedural Sedation’’. According to the RSS, a patient who no longer ‘‘responds to commands only’’ (patient does not make eye contact or respond to commands) is deemed to require capnography. The 2011 Guidelines specified that capnography was required only ‘‘when endotracheal tubes or laryngeal masks are inserted’’. This new requirement for capnography in sedated patients (RSS 4-6) also applies to patients whose airway has not been instrumented. Capnography has been routine monitoring in the operating room (OR) for more than twenty years, but, surprisingly, its use is still uncommon in most other areas (emergency room, intensive care unit, postanesthesia care unit, cardiac arrest carts, and out-of-OR sedation suites). Over the past ten to 15 years, there has been a steady increase in the number of investigators studying the role of M. M. Kurrek, MD (&) Department of Anesthesia, University of Toronto, 150 College Street, Room 121, Fitzgerald Building, Toronto, ON M5S 3E2, Canada e-mail: m.kurrek@utoronto.ca