© Springer International Publishing Switzerland 2017
Basavana G. Goudra and Preet Mohinder Singh (eds.)Out of Operating Room Anesthesia10.1007/978-3-319-39150-2_2222. Procedural Sedation in the Emergency Department
(1)
Department of Anesthesiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
(2)
Department of Emergency Medicine, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
Abstract
Procedural sedation in the emergency department is performed successfully across the country by many emergency medicine physicians. There are many varied styles of sedation in the ED that may vary from hospital to hospital. The required equipment, presences of additional providers, etc may vary slightly depending on the emergency department and its staffing complements. In addition, there are a variety of sedatives that may be used for sedation in the ED. Among the most common are ketamine and propofol, etomidate, and fentanyl/versed. Dexmedetomidine and remifentanyl remain on the horizon. Both the sedation practice and the need for the ED physician to also perform the procedure himself/herself make the style and technique of procedural sedation in the ED unique. It many ways it is very different from elsewhere in the hospital. However, the emergency medicine physician still maintains a high standard of care and a high quality safety margin. At all times there should be emergency airway equipment available. Also, an assessment of the urgency of the procedure is made by the ED physician. NPO status is less of a highlighted issue. In most all settings, it is also highly recommended that supplemental oxygen and capnography be used. The physician performing the sedation must be competent in emergency airway techniques.
Keywords
SedationEmergency departmentEmergency airway managementKetaminePropofolKetofolEtomidateFentanyl/versedCapnographyProvidersProcedural sedation in the emergency department is a unique subset of sedation. First of all, many emergency departments throughout the country only have one physician staffing their department. This opportunity lends itself to the development of a unique skillset. An emergency medicine physician must be able to multi-task in the fullest possible way. While simultaneously directing the sedation plan, he/she must also be tasked with performing the procedure. There are a variety of practice models for this plan. In some hospitals, a physician assistant may be present to help with the procedure. In academic centers, there are residents who are available to help with both sedation practice and procedural practice. However, in many EDs, there is a single provider who needs to be able to “do it all.” In addition to the physician, the American College of Emergency Physicians requires the presence of a certified provider to monitor the patient during sedation. In many EDs, this will be an emergency department nurse. Why is this unique? In virtually all other locations in the hospital, anesthesia staff are responsible for sedation practice. By the nature of the anesthesiologist’s training and practice, which begins in the operating room, there are two providers present for surgical/operative procedures. One is the sedation provider and one is the proceduralist/surgeon. In the emergency department, it may be one physician and a nurse. Due to the inherent difference among the different specialties, this is a unique difference in practice. Due to staffing constraints number of physicians available in the ED may be limited. Both models serve to provide safe and excellent patient care in different settings.
Before the procedure begins the emergency physician examines the patient and has a sense of the patient’s airway and potential airway complications. Although most emergency medicine physicians don’t formally assess or score Mallampati exams, they are certainly aware of the patient’s airway and its potential complications. Food intake is assessed and urgency of the procedure is addressed. Equipment is gathered prior to the start. The patient is placed on a cardiac monitor with telemetry, pulse oximetry, and in many places, capnography and/or respiratory rate monitoring. Suction is available and checked, intravenous access is obtained, airway equipment is made readily available, and the patient is consented both for the procedure and for the sedation.
What happens when the patient encounters complications during procedural sedation? Hypoxia and hypoventilation must be readily recognized. Often the patient is stimulated by voice, jaw thrust, or deep sternal rub. We believe that the best way to stimulate the patient is through jaw thrust. Not only is it a very stimulating maneuver, but it also serves to open the airway and help relieve any potential airway obstruction that may be occurring. If airway obstruction continues, a nasal trumpet can be placed. This too is a very stimulating maneuver and additionally serves to further open the airway and bypass any obstruction. Supplemental oxygen via nasal cannula (most often) serves to offer some buffer again the development of hypoxia during the sedation period. Based on available evidence we believe that capnography serves as the best gauge of depth of sedation and risk of the development of hypoxia. Hypoventilation will occur first, ahead of hypoxia, and if rapidly identified, adjustments can be made to prevent oxygen desaturation from occurring. In addition to cardiac monitor placement and capnography, the astute bedside physician is essential to the detection of hypoventilation and/or slowed minute ventilation. By simply watching the patient breathe, hypoventilation can easily be missed. Upper airway obstruction can be missed by only watching the rocking movements of the chest. While the chest may be moving in a rhythmic fashion consistent with breathing movements, upper airway obstruction may nonetheless be occurring. Most importantly, feeling the patient exhale onto the sedation providers gloved hand can rapidly detect or note the presence of exhaled gas flow due to the tactile stimulation of warm gas flow onto the provider. The sedation provider should use all senses to monitor depth and safety of sedation, including visual (capnography pattern, chest movements), auditory (pulse oximetry beeping, sonorous respirations), and tactile (warmth of exhaled gases on the clinician’s hand) senses.
Emergency Airway Management
What happens if the sedation is too deep for the stimulation level of the procedure, or if the patient progresses to a deeper plane of sedation than initially intended? Obviously the above manipulations are first attempted, including voice, jaw thrust, and/or sternal rub. If this does not suffice, a nasal trumpet may be placed assuming there are no contraindications such as facial fractures, coagulopathy, etc. If the patient’s breathing continues to decline, manual assisted ventilation must begin, often with a bag-valve-mask device or other circuit capable of delivering high flow oxygen. If the airway status continues to decline, on rare occasion, the patient may need to be intubated. The emergency medicine physician is skilled at emergency airway management and can quickly proceed with rapid sequence intubation. Pre-oxygenation is begun and suction is moved to the head of the bed. The most common drugs used for rapid sequence intubation in the ED are etomidate and succinylcholine. At times, rocuronium is also used. All ED patients are considered to have a full stomach and rapid sequence intubation is the safest method to secure the airway in the ED and prevent aspiration. Although it is rare to proceed with intubation during procedural sedation in the emergency department, it is essential to review the best means to perform it for the sake of completeness of the procedure and to fully review all aspects of procedural sedation in the ED [1].
There are many details essential to the performance of rapid sequence intubation in the emergency department. First of all, cricoid pressure was considered to be an essential part of the process for many years. An assistant places pressure over the mid trachea with two fingers in the hopes of closing the esophagus and preventing aspiration of stomach contents during the intubation process. Of late, there has been much discussion and debate as to the utility of this part of the procedure. Does cricoid pressure help? Does it prevent aspiration? The application of cricoid pressure developed in response to expert opinion. There was never a large body of evidence that prompted its use. It has recently been noted that indeed it may not prevent aspiration during rapid sequence intubation, but rather may worsen aspiration risk and cause harm. Cricoid pressure may increase peak inspiratory pressures during hand assisted ventilation, which may be necessary as a response to hypoxia. In turn, this may cause further gastric insufflation. Also, it may decrease lower esophageal pressure, thereby worsening aspiration risk. Often, it will worsen the view of the laryngoscopist during the intubation process. This can be extremely detrimental by delaying intubation. The best means to prevent aspiration during emergent intubation is to use rapidly acting induction anesthetics coupled with a rapidly acting neuromuscular blocking agent. With adequate pre-oxygenation, the goal is to avoid hand assisted ventilation whenever possible. This is the best way to prevent aspiration [2].
In addition, when rapid sequence intubation is performed in the ED, there is emerging evidence that success rates are higher with video laryngoscopy. Multiple studies have show that CMAC and/or GlideScope video laryngoscopy is more successful when compared to direct laryngoscopy in the ED. It is worth noting this prior to performing procedural sedation for many reasons. Where is the airway equipment? Is the suction being utilized? Are rapid sequence induction medications readily available? Are laryngoscope blades available? Is there a video laryngoscope available and if so where is it? All of the equipment should be checked and immediately available for use when performing procedural sedation in the ED.
Next we will discuss equipment needed for procedural sedation as well as the medications that are used for sedation.
Capnography, Supplemental Oxygen, and Ventilation Status During Procedural Sedation
As the use of procedural sedation continues to expand for painful and anxiety-provoking procedures in the emergency department, a well-controlled and monitored patient setting is of the utmost importance. Current guidelines from the American College of Emergency Physicians (ACEP) and the American Society of Anesthesiology (ASA) recommend continuous monitoring of respiratory and heart rate, blood pressure, and pulse oximetry during procedural sedation [3, 4]. New from previously published policy guidelines from both groups is a strong recommendation for capnography use from the American Society of Anesthesiology, and a Level B recommendation from the American College of Emergency Physicians (defined as reflecting moderate clinical certainty) that capnography may be used to monitor ventilation status as a means to detect apnea earlier than pulse oximetry alone. A 2009 randomized, controlled trial by Deitch et al. showed a 100 % sensitivity of capnography identifying hypoxia before onset during propofol sedation, with the authors concluding that capnography provides advance warning for all hypoxic events [5]. The median onset of hypoxia after respiratory depression (defined as capnography reading >50 mmHg) was 60 s in their study, demonstrating obvious clinical utility for end tidal CO2 monitoring. Advanced warning of hypoventilation or apnea can prompt the clinician to utilize airway adjuncts such as nasopharyngeal airways or bag valve masks if the need arises before oxygen desaturation occurs.
Supplemental oxygen is classically recommended as an adjunct to procedural sedation, however little data exists to date supporting a difference in significant outcomes with routine supplemental oxygen administration. Indeed, Deitch et al in 2008 did not show a significant decrease in hypoxia with supplemental oxygen via nasal cannula [6]. However, a 2011 randomized, controlled trial by the same group did show a clinically significant reduction in hypoxia during propofol sedation in a high-flow oxygen group (defined as 15 L/min via non-rebreather mask) when compared to 15 L/min flow of compressed air [7]. When choosing a sedative agent with apnea as a possible side effect, high-flow oxygen may be a useful supplement to procedural sedation.
Given the strong recommendations from both the ASA and ACEP on end-tidal CO2 monitoring, we recommend consideration of high-flow oxygen supplementation along with routine use of both pulse oximetry and capnography as the safest approach for all procedural sedations.
Number of Providers Required
Competency and privilege credentialing is institution specific, with varying numbers of required physicians or other healthcare providers (nurses, physician assistants, nurse practitioners). All hospital staff should be aware of their own department’s policies and guidelines for procedural sedation. The American College of Emergency Physicians provides a Level C recommendation (based on limited literature or expert consensus) for a “nurse or other qualified individual” to be present for monitoring the patient in addition to the medical provider performing the procedure [4]. The exact number and titles of providers necessary for procedural sedation is not specifically defined by either the ASA or ACEP, likely due to the void of evidence-based outcomes in the literature influenced by numbers and roles of providers. Two studies investigating single physician versus a two-physician procedural sedation team showed no statically significant difference in adverse events between the groups, where adverse events were defined as hypotension, hypoxia, apnea, or airway obstruction [8, 9]. Of note, the decision to staff each sedation with one or two physicians was made based on clinical judgment and not randomization, with no randomized trials existing to date comparing complication rates between single versus two-physician procedural sedation teams.
We recommend at least two healthcare providers (i.e. one physician and one nurse) be present for the entirety of the procedural sedation. Both providers should have experience with all drugs and monitoring equipment prior to the start of the procedure. Most importantly, any physician performing procedural sedation must be competent at both medical resuscitation and airway stabilization or intubation should the need arise.
Etomidate
Etomidate is an imidazole hypnotic that induces sedation via GABA receptors in the central nervous system. Etomidate is a common choice for induction of anesthesia or rapid sequence intubation, however a growing role for procedural sedation in the emergency department has been reported in the literature. The American College of Emergency Physicians currently gives a Level B recommendation (reflecting moderate clinical certainty) that etomidate can be administered safely to adults in the emergency department for procedural sedation [4]. Etomidate provides anxiolysis, sedation, and amnesia but has no analgesic properties. A short half-life makes etomidate ideal for brief but anxiety-provoking procedures in the emergency department.
Etomidate has similar pharmacological characteristics to propofol in regards to onset of action, clinical duration, and depth of sedation. Specifically, etomidate has an onset of action under 1 min, with a 5–10 min duration of moderate to deep sedation. The usual initial dose for procedural sedation with etomidate is 0.1–0.15 mg/kg intravenously [10, 11]. This dose may be repeated for clinical effect after 3–5 min. We recommend administering the intravenous dose over 30–45 s. A 2002 study by Vinson and Bradbury showed a mean cumulative dose of 0.2 mg/kg of intravenous etomidate for procedural sedation, with an additional 23 % of patient requiring additional medications (opiates and/or benzodiazepines) [12].
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