Alan C. Finley, MD, FASE

Roman Sniecinski, MD, FASE

Moderate sedation, often referred to as “conscious sedation,” for procedures involving echocardiography seems to be getting a lot of attention lately. Within the ASE, the Council of Perioperative Echocardiography (COPE) offers a unique perspective on this subject since a large percentage of COPE members are anesthesiologists. Before commenting on some of the recent dialogue, a brief review of the continuum of depth of sedation is warranted.

The degree of sedation provided to a patient does not have discrete levels, but is rather a continuum ranging from minimal sedation to general anesthesia. The level of sedation is independent of the route of drug administration, and deep levels of sedation can be achieved with many different medications. Even though practitioners may intend to perform moderate sedation, predicting an individual’s response to the various agents used can be difficult. This mandates that practitioners administering the sedation also have the ability to “rescue” patients who have achieved a deeper level of sedation than what was intended. Of central concern to this issue is monitoring and maintaining adequate ventilation and the potential need of placing an advanced airway. Monitored anesthesia care (MAC) is an often-misunderstood term which refers to a specific anesthesia service. MAC does not describe a specific depth of sedation, but includes everything along the continuum. MAC differs from sedation provided by a non-anesthesia provider in that someone is present who can escalate care to general anesthesia should the need arise.

In an effort to optimize the care for patients undergoing moderate sedation, the American Society of Anesthesiology has partnered with societies from various specialties and will soon be publishing an updated Practice Guidelines for Moderate Sedation and Analgesia. This document is too extensive to outline in its entirety, but the intent is to educate the proceduralist who directs sedation on topics such as appropriate patient selection, preprocedural preparation, intraprocedural monitoring, medication administration, and emergency support. Many ASE members will be focused on moderate sedation when it is performed during a transesophageal echocardiographic (TEE) examination. During a TEE examination, moderate sedation is often administered without the presence of an anesthesiologist and, with few exceptions, it is effective in providing the necessary analgesia and anxiolysis. However, inadequate sedation does occur and has the potential to cause unnecessary patient discomfort or injury. This is especially true when an additional procedure is added on to a TEE, such as a cardioversion for atrial fibrillation. Conversely, performing moderate sedation has the potential to result in a deeper level of sedation and significant cardiac and/or respiratory compromise must be recognized and managed appropriately. Failure to respect this possibility and disregarding standard safety measures can lead to catastrophic complications.

The risk of over-sedation is greatest when a sedative or analgesic medication designed for general anesthesia is administered with the intention of maintaining only moderate sedation. Because of the agent used, the care provided must remain consistent with that required for general anesthesia. For example, if a medication such as propofol is chosen for moderate sedation, then the risk of inadvertently administering a general anesthetic is high. In this case, an anesthesia care team should be present to provide general anesthesia if needed.

Recently, multiple manuscripts have been published regarding the use of sedation during transcatheter aortic valve replacement (TAVR). In a recent example, Hyman et al . used observational data from the STS/ACC TVT registry and concluded that conscious sedation is associated with a shorter hospital stay and lower 30-day mortality than general anesthesia. Many anesthesiologists have listened to the dialogue surrounding this topic with great concern. Observational studies are significantly limited by selection bias, which is especially difficult to control for in a registry dataset not designed to collect anesthesia-related information. Anesthesiologists who care for TAVR patients identify several risk factors that make moderate sedation hazardous and often choose general anesthesia from the start. Common patient comorbidities that will prompt choosing a general anesthetic include orthopnea, obstructive sleep apnea, obesity, a difficult airway, respiratory disease, right heart dysfunction, lack of patient cooperation, and a low patient pain tolerance. Without including these variables that affect choices about anesthetic technique, conclusions reached from the observational trials such as Hyman et al . should be interpreted with caution.

Perhaps more concerning is the possibility that a proceduralist will use studies such as Hyman et al. ’s to justify performing TAVRs with moderate sedation in an interventional suite without an anesthesia care team present. The worry is not that these procedures can be performed safely with moderate sedation, but whether or not they will be performed without MAC. Beyond managing sedation depth, the potential for an emergency surgical procedure necessitates anesthesiologist involvement to escalate care immediately to general anesthesia should the need arise. In these situations, a delay in this care has the potential to result in preventable morbidity and mortality.

Optimal sedation management for patients undergoing invasive procedures involves many considerations. For many procedures, performing moderate sedation is both an effective and safe choice. However, many patient variables must be considered by those with experience in general anesthesia to determine if moderate sedation is appropriate. Furthermore, proceduralists should not disregard the potential morbidity introduced to a patient in emergent situations if the anesthetic level cannot be escalated to a general anesthetic in a timely manner.

Alan C. Finley, MD, FASE is a cardiac anesthesiologist and associate professor at the Medical University of South Carolina and is Chair of the ASE Council on Perioperative Echocardiography Steering Committee.

Roman Sniecinski, MD, FASE is an Associate Professor of Anesthesiology in the Division of Cardiothoracic Anesthesia at Emory University School of Medicine. He is the past Chair of the ASE Council of Perioperative Echocardiography steering committee.

Editorial note: This article does not necessarily reflect the viewpoints or policies of the ASE organization. This article was submitted by two ASE Council volunteers, and the organization is grateful to them and our other members who contribute to the JASE blue pages as we value their willingness to share their personal and professional insights and experiences with the ASE community.