Triage, Sedation and Monitoring

Minimal sedation (anxiolysis)

Moderate sedation/analgesia

Deep sedation/analgesia

General anesthesia

Responsiveness

Normal response to verbal stimuli

Purposeful response to verbal or tactile stimulation

Purposeful response after repeated/painful stimulation

No response, even with painful stimulation

Airway

Unaffected

Intervention may be required

Intervention often required

Spontaneous respiration

Unaffected

May be inadequate

Intervention often required

Cardiovascular function

Unaffected

Usually maintained

May require intervention

Adapted from Gross JB et al. American Society of Anesthesiologists Task Force on Sedation and Analgesia by Non-Anesthesiologists. Practice guidelines for sedation and analgesia by non-anesthesiologists. Anesthesiology 2002;98:1005

As with other aspects of medical care, endoscopic emergencies need to be evaluated on a case-by-case basis with regard to timing (early vs. late) and location of the procedure in order to optimize procedural safety and success. As an example, patients presenting with upper GI bleeding (UGIB) who undergo early endoscopic intervention (within 24 h) appear to spend less days as inpatients in the ICU [5] and hospital [6]. More recent evidence suggests that delay in performing endoscopic retrograde cholangiopancreatography (ERCP) within 48 h of the index presentation for acute cholangitis leads to increased 30-day readmission rates [7]. Timing of intervention for foreign body ingestion and food impaction is related to the clinical presentation, type of object ingested, and ability to handle secretions [8], with early intervention advocated when signs of high-grade obstruction are present.

Sedation

Several sedatives and anesthetic agents are available for administration during procedures. Endoscopists should be familiar with the depth of sedation these agents provide, their duration of action, side effects, and if available, appropriate reversal agents. This information is even more important during emergent endoscopic procedures as patients may already be at higher risk for cardiopulmonary adverse events. The degree of sedation needed to successfully complete a procedure ranges from moderate sedation to general anesthesia (Table 1.1). The decision on optimizing the depth of sedation should be made from the type of emergency encountered and, more importantly, the patient’s medical comorbidities. As sedation depth is a continuum with no clearly defined boundaries, endoscopists must be prepared for managing deeper levels of sedation than planned [3, 9].

Utilization of the ASA PS prior to endoscopy should assist in the choice of agents used and determine if the support of a dedicated anesthesia team is indicated. In non-emergent situations, ASA PS 1 and 2 patients are considered appropriate candidates for moderate sedation, whereas ASA PS 3 patients should be carefully evaluated for requirement of anesthesia support, and ASA PS 4 and 5 patients will require anesthesia assistance. In emergent situations, the risk for pulmonary aspiration and cardiopulmonary adverse events should also be taken into account, regardless of ASA PS.

Pharmacologic Therapy

There are a variety of sedative, analgesic, and hypnotic agents available for use in endoscopy. In the United States, most patients receive a combination of benzodiazepine and an opioid for routine EGD or colonoscopy [10]. The most commonly utilized benzodiazepine is midazolam due to its shorter duration and onset of action; however, other benzodiazepine agents can be used as adjuvant or primary sedative therapy. Opioids that are commonly used include fentanyl and meperidine , the choice of which is generally made at the discretion of the endoscopist. Propofol , a short-acting drug with sedative, amnestic, and hypnotic properties, can be used alone or in combination with other agents. The choice of which medications to use is for the most part influenced by institutional privileges (e.g., propofol), endoscopist preference, and type of intervention to be performed. Table 1.2 summarizes the pharmacological agents that are more likely to be used in emergent scenarios [11].

Table 1.2

Selected pharmacological agents for sedation and analgesia

Drug	Onset of action, min	Peak effect, min	Duration of effect, min	Pharmacological antagonist	Side effects
Midazolam	1–2	3	15–80	Flumazenil	Respiratory depression
Diazepam	2–3	3–5	360	Flumazenil	Respiratory depression
Fentanyl	1–2	3–5	30–60	Naloxone	Respiratory depression
Meperidine	3–6	5–7	60–180	Naloxone	Respiratory depression
Propofol	<1	1–2	4–8	None	Respiratory depression, hypotension

Adapted from Vargo JJ et al. Multisociety sedation curriculum for gastrointestinal endoscopy. Gastrointest Endosc. 2012;76:e1–25

Benzodiazepines

Moderate sedation with benzodiazepines (in combination therapy with opioids) is the most common form of sedation used in endoscopic procedures around the world [12] and can be used in many emergent endoscopic scenarios. In a randomized control trial that compared three groups (diazepam only, midazolam only, or no sedation) in patients undergoing EGD, midazolam increased patient tolerance and had a higher amnestic effect than in patients who received diazepam [13]. Moreover, midazolam is generally favored over diazepam due to its shorter duration of action. The popularity of benzodiazepines is due to their relatively low cost, wide availability, and desired effects, including sedation, hypnosis, retrograde amnesia, and muscle relaxation [2]. Also, the synergistic effect with other sedatives and opioids is a key characteristic that can be used to decrease undesired effects associated with higher doses of each individual agent. Prior to administration in emergent scenarios, the endoscopist should be aware of the dose-dependent effect of benzodiazepines on ventilatory depression and their ability to alter hemodynamics by inducing hypotension and tachycardia [14]. Due to their metabolism and excretion patterns, the use of benzodiazepines in the geriatric population [15] and in patients with known hepatic or renal dysfunction requires dose adjustments.

Opioids

Opioid administration in endoscopy primarily provides analgesia with some mild sedative effects. When used in combination with benzodiazepines, an optimal combination of sedation and analgesia can be achieved, although depth of sedation must be monitored closely. In one study, the combination therapy of meperidine and midazolam in ASA PS 1 and 2 patients targeting moderate sedation in routine and advanced endoscopic procedures lead to deep sedation in 68 % of cases [9]. This should be emphasized in the setting of emergent endoscopic procedures where airway management is critical and close monitoring of depth of sedation by the endoscopy team is essential. In regard to opioid agents, fentanyl shortened total procedure and recovery times when compared to meperidine during routine endoscopy in one study; however, patients felt less overall pain during the procedure when meperidine was used [16]. Both meperidine and fentanyl can cause depression of central ventilatory drive, which may lead to sentinel cardiopulmonary adverse events. It should also be noted that meperidine has an active metabolite normeperidine, which may add to the drug’s longer effect when compared to fentanyl. Therefore, diligent airway monitoring during emergent endoscopic procedures for which these agents are utilized is necessary.

Propofol

Propofol (2,6-diisopropylphenol) is an ultrashort-acting hypnotic agent with sedative, antiemetic, hypnotic, and amnestic effects [2]. Propofol has no analgesic effect and, due to preparation methods, is contraindicated in patients with egg or soybean allergies. Recovery is fast, usually within 10–20 min of discontinuation, regardless of the total dose administered [17]. The primary disadvantages of propofol are the inability to easily titrate to desired levels of sedation without inducing general anesthesia and the lack of available pharmacological antagonists. In most areas of the United States, propofol must be administered with the assistance of an anesthesiologist, although there are data supporting the safety profile of endoscopist and nurse-administered propofol sedation. During emergent endoscopic procedures, it must be noted that propofol can induce dose-dependent hypotension; this occurs more frequently during bolus administration, and slow initial administration is therefore advised. Airway management is also critical with propofol sedation, and the endoscopy team must be able to rescue a patient who is unable to protect his or her airway or loses spontaneous respiratory function [2]. Propofol can be used in combination with benzodiazepines or opioids, allowing for more optimal control of dose-dependent adverse effects of all agents administered. This is optimal as studies have shown that combination therapy with propofol and fentanyl or midazolam allows moderate sedation to be achieved [18, 19].

Monitoring

The standard of care for patients undergoing any form of endoscopic evaluation that requires sedation includes cardiopulmonary monitoring prior to, during, and after the procedure. This generally includes pulse oximetry, continuous electrocardiographic (ECG) monitoring, and automated blood pressure monitoring [20]. These monitoring devices and the trained endoscopy personnel who are assessing the patient’s cardiorespiratory status are critical during endoscopic emergencies. In elective endoscopy , unplanned adverse events are rare, occurring in 1.4 % of procedures [1]. Based on an assessment of the CORI database to evaluate the occurrence of cardiopulmonary adverse events in 324,737 procedures completed with moderate sedation, risk factors included inpatient status, advanced age, and higher ASA PS classification [1]. Patients undergoing inpatient procedures were found to be sicker (56 % with ASA PS ≥ 3), and inpatient procedures were often more complex. This exemplifies the type of scenario where the majority of emergent endoscopic interventions will occur, and diligent safety monitoring in this population becomes even more critical.

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