Systemic Analgesia and Sedation for Procedures

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Chapter 33

Systemic Analgesia and Sedation for Procedures

Baruch Krauss and Steven M. Green

Procedural sedation and analgesia (PSA) refers to the use of analgesic, dissociative, and sedative agents to relieve the pain and anxiety associated with diagnostic and therapeutic procedures performed in various settings. PSA is an integral element of emergency medicine residency and pediatric emergency medicine fellowship training and curricula, and graduates of these programs are skilled in the practice of PSA. Emergency clinicians are skilled in resuscitation, vascular access, and advanced airway management, which permits them to effectively recognize and manage the potential complications associated with PSA.¹

In a recent study of all practitioners, the most common clinical errors associated with PSA were delayed recognition of respiratory depression and arrest, inadequate monitoring, and inadequate resuscitation,² mistakes that are unlikely to be made by emergency clinicians. The safety of PSA techniques by emergency clinicians has been well documented in numerous series in both children and adults.^3–7 Safe and successful application of PSA requires careful patient selection, customization of therapy to the specific needs of the patient, and careful monitoring of patients for adverse events. Emergency clinicians must ensure that all patients receive pain relief and sedation commensurate with their individual needs during any procedure.

Terminology

The progression from minimal sedation to general anesthesia is a nonlinear continuum that does not lend itself to division into arbitrary stages. Low doses of opioids or benzodiazepines induce mild analgesia or sedation, respectively, with little danger of adverse events. If, however, clinicians continue administering additional medication beyond this initial level, progressively altered consciousness ensues with a proportionately increased risk for respiratory and airway complications. If further medications are administered, the patient will advance along this continuum until protective airway reflexes are lost and general anesthesia is ultimately reached. This continuum of sedation is not drug specific in that varying states from mild sedation to general anesthesia can be achieved with virtually all nondissociative PSA agents (e.g., opioids, benzodiazepines, barbiturates, etomidate, propofol).

In 1985, the American Academy of Pediatrics (AAP) and the National Institutes of Health issued guidelines for the management and monitoring of children receiving sedation for diagnostic and therapeutic procedures in response to the growing use of opioids and sedative-hypnotic agents in the outpatient setting and a number of sedation-related deaths.8,9 In these documents, three levels of sedation were defined (conscious sedation, deep sedation, general anesthesia) to create a common language for describing drug-induced alterations in consciousness (Box 33-1).^10,11 A key development in the field of PSA has been revision of the original terminology and adoption of clearer descriptions of varying types and degrees of sedation (see Box 33-1). Though historically popular, the widely misinterpreted and misused term “conscious sedation” has fallen into disfavor¹²; it has been labeled as “confusing,”¹³ “imprecise,”¹² and an “oxymoron”^12,13 and has been replaced with the term “moderate sedation.”¹⁰

Box 33-1 PSA

Terminology and Definitions

General

• Analgesia¹⁰: Relief of pain without intentional production of an altered mental state such as sedation. An altered mental state may be a secondary effect of medications administered for this purpose.

• Anxiolysis¹⁰: A state of decreased apprehension concerning a particular situation in which there is no change in a patient’s level of awareness.

• PSA³: A technique of administering sedatives, analgesics, dissociative agents, or any combination of such agents to induce a state that allows the patient to tolerate unpleasant procedures while maintaining cardiorespiratory function. PSA is intended to result in a depressed level of consciousness but one that allows the patient to maintain airway control independently and continuously. Specifically, the drugs, doses, and techniques used are not likely to produce loss of protective airway reflexes.

Current Sedation State: Terminology

• Minimal sedation (anxiolysis)¹⁰: A drug-induced state during which patients respond normally to verbal commands. Although cognitive function and coordination may be impaired, ventilatory and cardiovascular function is unaffected.

• Moderate sedation (formerly conscious sedation)¹⁰: A drug-induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation. Reflex withdrawal from a painful stimulus is not considered a purposeful response. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate. Cardiovascular function is usually maintained.

• Dissociative sedation¹¹: A trancelike cataleptic state induced by the dissociative agent ketamine and characterized by profound analgesia and amnesia with retention of protective airway reflexes, spontaneous respirations, and cardiopulmonary stability.

• Deep sedation¹⁰: A drug-induced depression of consciousness during which patients cannot be easily aroused but respond purposefully after repeated or painful stimulation. The ability to independently maintain ventilatory function may be impaired. Patients may require assistance in maintaining a patent airway, and spontaneous ventilation may be inadequate. Cardiovascular function is usually maintained.

• General anesthesia¹⁰: A drug-induced loss of consciousness during which patients cannot be aroused, even by painful stimulation. The ability to independently maintain ventilatory function is often impaired. Patients frequently need assistance in maintaining a patent airway, and positive pressure ventilation may be required because of depressed spontaneous ventilation or drug-induced depression of neuromuscular function. Cardiovascular function may be impaired.

PSA, procedural sedation and analgesia.

Despite improvements in PSA terminology, the system is imperfect and there is still no objective way to assess the depth of sedation. Levels of responsiveness remain at best crude surrogate markers of the respiratory drive and retention of protective airway reflexes. This is especially true for all levels of sedation in young children (infants and toddlers) who do not understand or are unreliable in following verbal commands. Although respiratory depression and respiratory arrest can be detected quickly with standard interactive and mechanical monitoring, there is no safe and practical way to assess the status of protective airway reflexes. Data are currently insufficient to determine whether deep sedation is associated with impairment of protective reflexes or whether such danger is encountered only when “pushing” deep sedation to the point at which it approaches or reaches general anesthesia.

PSA Guidelines

Before the promulgation of PSA guidelines by specialty societies and governmental agencies, clinicians simply administered sedatives in varied clinical settings and used individual judgment to determine the need for specific monitoring devices and supporting personnel. Since 1985, at least 27 sets of PSA guidelines have been published,¹⁵ each crafted for the unique and differing settings in which PSA is practiced. Naturally, not all are in agreement.⁵ The intent of each of these guidelines is to better standardize the manner in which PSA is performed to enhance patient safety. Those most pertinent to emergency clinicians are from the American College of Emergency Physicians,³ the AAP,¹⁶ and the American Society of Anesthesiologists (ASA).^14,17

In the early 1990s, the Joint Commission on Accreditation of Healthcare Organizations, an independent, not-for-profit organization that evaluates and accredits hospitals in the United States, took a special interest in PSA, with the central theme being that the standard of sedation care provided should be comparable throughout a given hospital. Thus, patients sedated in the emergency department (ED) should not receive a significantly different level of attention or monitoring than those sedated for a similar-level procedure in the operating room or in the endoscopy suite. To ensure this, the Joint Commission requires specific PSA protocols to be applied consistently throughout each institution. These hospital-wide sedation policies will vary from site to site based on the specific needs and expertise available within each institution. In 2001, the Joint Commission released new standards for pain management, sedation, and anesthesia care.¹⁰

At each hospital accreditation survey the Joint Commission determines whether practitioners practice PSA consistently with their hospital-wide sedation policy and whether they provide sufficient documentation of such compliance. Clinicians must be familiar with their hospital’s sedation policies and should work with their medical staff to ensure that such policies are suitably detailed, yet reasonable and realistic. Unduly restrictive policies do a disservice to patients by discouraging appropriate levels of analgesia and anxiolysis. Most hospitals pattern their sedation policies after the Joint Commission standards and definitions. It is important to note that the unique ketamine dissociative state does not fit into the existing Joint Commission definitions of sedation and anesthesia.¹¹ A ready solution is to assign a distinct definition for “dissociative sedation” (see Box 33-1).

The Joint Commission requires that PSA practitioners who are permitted to administer deep sedation be qualified to rescue patients from general anesthesia.¹⁰ Emergency clinicians typically perform all levels of sedation except general anesthesia. Moderate sedation suffices for the majority of procedures in adults and cooperative children, although it will not be adequate for extremely painful procedures (e.g., hip reduction, cardioversion). Deep sedation can facilitate such procedures, but with greater risk for cardiorespiratory depression than is the case with moderate sedation. Moderate sedation is frequently insufficient for effective anxiolysis and immobilization in younger, frightened children, and deep or dissociative sedation is an appropriate alternative.

Evaluation before PSA

The practice of PSA has three essential components performed in sequence: the initial presedation evaluation, sedation during the procedure, and postprocedure recovery and discharge from the ED. In all but the most emergency situations, perform a directed history and physical examination before PSA. If this evaluation suggests additional risk, reconsider the advisability of sedation. High-risk cases may be better managed in the more controlled environment of the operating room.

Presedation assessment is a Joint Commission requirement, and most hospitals have developed specific forms to facilitate consistent documentation of the involved items. In general, however, all the appropriate parameters are already documented in the general ED record or are obvious by simply evaluating the patient’s complaint. Except in emergency situations, discuss the risks, benefits, and limitations of any PSA with the patient or parent or guardian in advance and obtain verbal agreement. Formal written informed consent is not required as a standard of care (unless a local institutional requirement), although documentation, as discussed earlier, is essential.

General

Assess the type and severity of any underlying medical problems. This is usually best documented by the standard ED medical record, history, physical examination, and nursing notes. Another tool used for this purpose is the ASA physical status classification for preoperative risk stratification (Table 33-1). Verify current medications and allergies. Inquire about previous adverse experiences with PSA or anesthesia.

TABLE 33-1

ASA Physical Status Classification

ASA, American Society of Anesthesiologists.

From Krauss B, Green SM. Sedation and analgesia for procedures in children. N Engl J Med. 2000;342:938.

(From Green SM, Roback MG, Miner JR, et al. Fasting and emergency department procedural sedation and analgesia: a consensus-based clinical practice advisory. Ann Emerg Med. 2007;49:454.)

More conservative guidelines from the ASA for elective surgery or procedures in healthy patients specify an age-stratified fasting requirement of 2 to 3 hours for clear liquids and 4 to 8 hours for solids and nonclear liquids.¹⁹ Nonetheless, they acknowledge that regarding PSA, “the literature provides insufficient data to test the hypothesis that preprocedure fasting results in a decreased incidence of adverse outcomes.”^14,17 The concept of preprocedure fasting is logistically difficult or impossible for emergency clinicians, who have no control over patients’ oral intake before arrival at the ED. In actual practice, emergency clinicians routinely perform PSA safely on patients who are noncompliant with the ASA elective-procedure fasting guidelines.^18–20 Procedures can sometimes be delayed for a number of hours; however, this must be balanced against prolongation of pain and anxiety in the patient, inconvenience for the patient and family, and expenditure of room space and other finite ED resources. In addition, many ED procedures require urgent if not immediate attention (e.g., débridement and repair of animal bite wounds, acute burn management, arthrocentesis for suspected septic arthritis, reduction of joint dislocations, lumbar puncture in an uncooperative septic patient, hernia reduction, eye irrigation for ocular trauma or chemical burns, cardioversion in a hemodynamically unstable patient). Though uncommon, there may be occasions in which nonfasting patients require urgent procedures with a substantial depth of sedation that may be more safely managed in the operating room with endotracheal intubation to protect the airway.

Selecting agents that are less likely to produce vomiting, such as fentanyl instead of morphine or meperidine, may decrease the potential for aspiration. Concomitant antiemetic administration is an unproven adjunct but a common consideration. In summary, common sense should apply and clinical judgment should prevail, but it is standard for PSA to be performed in the ED on patients in the nonfasting state.

Hepatic and Renal

The implications of delayed metabolism or excretion of PSA agents in infants younger than 6 months, in the elderly, and in patients with hepatic or renal abnormality should be considered.

Personnel and Interactive Monitoring

The most important element of PSA monitoring is close and continuous observation of the patient by an individual capable of recognizing complications of sedation (Fig. 33-2). This person must be able to continuously observe the patient’s face, mouth, and chest wall motion. Equipment or sterile drapes must not interfere with such visualization. Such careful observation allows prompt detection of adverse events such as respiratory depression, apnea, partial airway obstruction, emesis, and hypersalivation.

Figure 33-2 Procedural sedation and analgesia (PSA). ECG, electrocardiographic.

PSA personnel should understand the pharmacology of analgesic and sedative agents and their respective reversal agents. They must be proficient in maintaining airway patency and assisting ventilation if needed. PSA requires a minimum of two experienced individuals, most frequently one clinician and one nurse or respiratory therapist. The clinician typically oversees drug administration and performs the procedure, whereas the nurse or respiratory therapist continuously monitors the patient for potential complications. The nurse or respiratory therapist should also document the medications administered and the response to sedation and measure vital signs periodically. The nurse or respiratory therapist may assist in minor, interruptible tasks but must remain focused on the patient’s cardiopulmonary status, and this responsibility must not be impaired. An individual with advanced life support skills should also be immediately available, which is a requisite easy to fulfill in the ED setting.

During deep sedation, the individual dedicated to patient monitoring should have experience with this depth of sedation and no other responsibilities that would interfere with the advanced level of monitoring and documentation appropriate for this degree of sedation.¹⁶ Individual hospital-wide sedation policies may have additional requirements regarding how and when deep sedation is administered based on the patient’s specific needs and the clinician’s expertise.

It is not mandatory to have intravenous (IV) access in situations in which sedation is administered by the intramuscular (IM), oral, nasal, inhalational, or rectal routes, but it may be preferable based on the anticipated depth of sedation or comorbid condition or for additional drug titration. When sedation is performed without IV access, an individual skilled in initiating such access should be immediately available.

Equipment and Mechanical Monitoring

The routine use of mechanical monitoring has greatly enhanced the safety of PSA. With current technology, oxygenation (via pulse oximetry), ventilation (via capnography), and hemodynamics (via blood pressure and electrocardiogram [ECG]) can all be monitored noninvasively in nonintubated, spontaneously breathing patients.

Pulse Oximetry

Mechanical monitoring for PSA should include continuous pulse oximetry with an audible signal. Pulse oximetry measures the percentage of hemoglobin that is bound to oxygen and is not a substitute for monitoring ventilation because of the variable lag time between the onset of hypoventilation or apnea and a change in the oxygen saturation of hemoglobin molecules.

Capnography

Capnography is a very useful tool that provides a continuous, breath-by-breath measure of the respiratory rate and CO₂ exchange. Importantly, capnography can detect the common adverse airway and respiratory events associated with PSA.21–33 Capnography is the earliest indicator of airway or respiratory compromise and will show abnormally high or low end-tidal carbon dioxide pressure well before pulse oximetry detects falling oxyhemoglobin saturation, especially in patients receiving supplemental oxygen. Early detection of respiratory compromise is especially important in infants and toddlers, who have smaller functional residual capacity and greater oxygen consumption than older children and adults do.^34–36 Capnography provides a non–impedance-based respiratory rate directly from the airway (via an oral-nasal cannula). This is more accurate than impedance-based respiratory monitoring, especially in patients with obstructive apnea or laryngospasm, in whom impedance-based monitoring will interpret chest wall movement without ventilation as a valid breath.

Two recent randomized controlled trials have demonstrated that the use of capnography during procedural sedation decreases the incidence of hypoxic events.37–39 Both studies randomized patients to standard monitoring alone (oximetry, ECG, and blood pressure) or standard monitoring with capnography, with hypoxia being the outcome measure. In both studies, the addition of capnography to standard monitoring alerted clinicians to ventilatory abnormalities before the development of hypoxia, and as a result, capnography significantly decreased the incidence of hypoxic events.^37,38

At this time the American College of Emergency Physicians has no current standards for the use of capnography during PSA. Currently, the use of capnography in the ED for PSA varies widely.

ECG Monitoring

Although continuous ECG monitoring cannot be considered mandatory or standard of care in the absence of cardiovascular disease, such monitoring is simple, inexpensive, and readily available.

BIS Monitoring

The bispectral index (BIS) is a monitoring modality that uses a processed electroencephalogram signal to quantify the depth of anesthesia or sedation. A BIS value of 100 (unitless scale) is considered complete alertness, 0 represents no cortical activity at all, and the range of 40 to 60 is believed to be consistent with general anesthesia. Although this technology has been used widely to monitor the depth of sedation in the operating room, the ASA has judged that its clinical applicability for this purpose “has not been established.”⁴⁰ Furthermore, a 2011 study found that patients in whom a modified minimum alveolar concentration protocol (i.e., the inhalational anesthetic concentration needed for 50% of patients to not move with the application of a noxious stimulus) was used had fewer awareness events than did those in whom a BIS protocol was used.⁴¹ Even though PSA research has demonstrated statistical associations between BIS and standard sedation scores, these studies have also noted unacceptably wide ranges of BIS values at various depths of sedation.^21,42–46 Thus, although BIS is correlated with the depth of sedation in aggregate groups, it lacks sufficient capacity to reliably gauge such depth in individual patients and therefore cannot currently be recommended for ED PSA.

Resuscitation Equipment and Supplies

Gather all necessary age-appropriate equipment for airway management and resuscitation in the sedation area, including oxygen, a bag-valve-mask device, suction, and drug reversal agents. For subjects with significant cardiovascular disease, include a defibrillator as well.

Vital Signs

Measure vital signs periodically at individualized intervals, in most cases including measurements at baseline, after drug administration, on completion of the procedure, during early recovery, and at completion of recovery. During deep sedation it is reasonable to assess vital signs approximately every 5 minutes. Patients are at highest risk for complications 5 to 10 minutes after IV medications are administered and during the immediate postprocedure period when external stimuli are discontinued. Continuous monitoring of the ECG, blood pressure, pulse rate, and pulse oximetry via a standard monitor generally fulfills the monitoring requirements. Actual documentation in the medical record varies, and fewer entries on the record are necessary when continuous monitoring is used. There are no standards mandating the frequency of documentation of vital signs in the medical record, and guided by the specific patient scenario, medications used, and depth of sedation, common sense should prevail.

Supplemental Oxygen

Substantial variation in practice exists with regard to the use of supplemental oxygen during PSA. The premise is a logical one—increasing systemic oxygen reserves should naturally delay or perhaps avert hypoxemia should an airway or respiratory adverse event occur. However, the price paid for this well-intentioned safeguard is the loss of pulse oximetry as an early warning device.12,15,21 Hyperoxygenated patients will desaturate only after the apnea is prolonged—indeed, the time required for preoxygenated, apneic, healthy adults and adolescents to desaturate to 90% averages more than 6 minutes.^47,48

Deitch and colleagues have shown in a series of randomized controlled trials that high-flow supplemental oxygen decreases the incidence of hypoxia during propofol sedation (number needed to benefit of 4)⁴⁹ whereas lesser amounts of oxygen (3 L/min) do so only marginally with propofol and not at all with lighter levels of sedation.^23,50 Thus, high-flow oxygen is strongly recommended with propofol or other deep sedation, assuming that interactive monitoring includes capnography to promptly identify respiratory depression.^51,52 For lighter levels of sedation, supplemental oxygen has no established benefit and may impair detection of respiratory depression when using pulse oximetry without capnography.⁵²

Discharge Criteria

Monitor all patients receiving PSA until they are no longer at risk for cardiorespiratory depression (Table 33-2). Before discharge be sure that patients are alert and oriented (or have returned to an age-appropriate baseline) with stable vital signs. Many hospitals have chosen to use standardized recovery scoring systems similar to those used in their surgical postanesthesia recovery areas (Table 33-3). Although no generally accepted minimum durations for safe discharge have been established, one large ED study found that in children with uneventful sedation, no serious adverse effects occurred more than 25 minutes after final medication administration.⁵³ This suggests that in most cases, prolonged observation beyond hour is unlikely to be necessary.

TABLE 33-2

Complications after Sedation

From Krauss B, Brustowicz R, eds. Pediatric Procedural Sedation and Analgesia. Philadelphia: Lippincott, Williams & Wilkins; 1999:145.

TABLE 33-3

Sample Recovery Scoring Systems

From Krauss B, Brustowicz R, eds. Pediatric Procedural Sedation and Analgesia. Philadelphia: Lippincott, Williams & Wilkins; 1999:157.

Make sure that all patients leave the hospital with a reliable adult who will observe them after discharge for postprocedural complications. Document the name of the individual in the hospital record. Give written instructions regarding appropriate diet, medications, and level of activity (Boxes 33-2 and 33-3). Even though patients may appear awake and able to comprehend instructions, they may not remember details once they leave the ED.

Box 33-2 Sample Adult Disposition Instructions after PSA

1. Do not drive or operate heavy machinery for 12 hours.

2. Eat a light diet for the next 12 hours.

3. Take only your prescribed medications as needed, including any pain medication you were discharged with. Avoid alcohol.

4. Do not make any important decisions or sign important documents for 12 hours. You may be forgetful because of the medications that were administered.

5. If you experience any difficulty breathing or persistent nausea and vomiting, return to the emergency department.

6. You should have a responsible person with you for the rest of the day and during the night.

PSA, procedural sedation and analgesia.

Box 33-3 Sample Pediatric Disposition Instructions after PSA

Your child has been given medicine for sedation and/or pain control. These medicines may cause your child to be sleepy and less aware of the surroundings, thus making it easier for accidents to happen while walking or crawling. Because of these side effects, your child should be watched closely for the next few hours. We suggest the following:

1. No eating or drinking for the next 2 hours. Infants may resume half-normal feedings when they are hungry.

2. No playing for 12 hours that requires normal coordination, such as bike riding or jungle gym activities.

3. No playing without an adult to watch and supervise for the next 12 hours.

4. No baths, showers, cooking, or use of potentially dangerous electrical appliances unless supervised by an adult for the next 12 hours.

If you notice anything unusual about your child, call us for advice or return to the emergency department for reevaluation.

PSA, procedural sedation and analgesia.

To be eligible for safe discharge, children are not required to walk unaided or demonstrate that they can tolerate an oral challenge because most PSA agents are emetogenic. Forcing fluids after sedation can lead to emesis before or after discharge. The AAP guidelines require only that “the patient can talk (if age-appropriate)” and “the patient can sit up unaided (if age-appropriate).”¹⁶ When infants and young children are discharged after their evening bedtime, caution parents to position the child’s head in the car seat carefully. Significant forward flexion might cause airway obstruction if the child falls asleep on the way home.

General Principles

Therapeutic mistakes that result in inadequate analgesia and sedation include using the wrong agent, the wrong dose, the wrong route or frequency of administration, and poor use of adjunctive agents. With proper training and technique, adequate PSA can be provided in almost any circumstance. Understanding titration principles is critical to providing safe and effective PSA. Clinicians must have a thorough knowledge of the pharmacokinetics, dosing, administration, and potential complications of the PSA agents that they use. Time of onset from injection to the initial observed effect must be appreciated, especially when using drugs in combination, to avoid stacking of drug doses and oversedation.

The correct agent (or combination of agents) and the route and timing of administration depend on the following factors: How long will the procedure last? Will it be seconds (e.g., simple relocation of a dislocated joint, incision and drainage of a small abscess, cardioversion), minutes (e.g., complex manipulation of a fracture for reduction, breaking up loculations in a large abscess and then packing it), or prolonged (e.g., complex facial laceration repair)? How likely is it that the procedure will need to be repeated (e.g., fracture reduction)? Can topical, local, or regional anesthesia be used as an adjunct? Does the patient require sedation only for a noninvasive diagnostic imaging study?

Before drug administration, every effort should be made to minimize a patient’s anxiety and distress, particularly in children. The emotional state of a patient on induction strongly correlates with the degree of distress on emergence and in the days immediately after the procedure.54–57 Avoid being pressured by consultants to cut corners or rush PSA. Incorporating into the presedation preparation a discussion with the consultant about the sedation plan and the length of time required to safely prepare and sedate the patient can avoid the risks associated with hurried sedation.

For pediatric PSA, the clinician should appreciate the adult dose of the sedative being administered and consider this the maximum threshold. Understand that the initial dose of midazolam for PSA in a 100-kg patient on a milligram-per-kilogram basis is far less than the 0.1 mg/kg used in a child to avoid unexpected mishaps in drug dosing.

Routes of Administration

For nondissociative agents, titrate the IV medications to the patient’s response for the best method of achieving rapid and safe analgesia and sedation. Wait the appropriate time for the medications to produce the intended effect before adding more doses. When using opioids, administer doses in 2- to 3-minute increments and observe for side effects such as miosis, somnolence, decreased responsiveness to verbal stimuli, impaired speech, and diminished pain on questioning as appropriate initial end points. For sedative-hypnotics, use similar incremental dosing and end points such as ptosis (rather than miosis), somnolence, slurred speech, and alterations in gaze. Repeated doses may be given in a titrated fashion based on the patient’s response during the procedure.

The oral, transmucosal (i.e., nasal, rectal), and IM routes are more convenient means of administration because IV access is not necessary, but they are much less reliable for timely dose titration to a desired response. New drug delivery systems, however, are expanding the effectiveness and ease of use of these routes of administration. The refinement of intranasal drug delivery has significantly increased the efficacy of this route of administration.58,59 Before the development of metered-dose atomizers, the degree of absorption and effectiveness of intranasal drug administration were operator dependent. Furthermore, new drug formulations with concentrations appropriate for intranasal administration are becoming available for study.^60,61

The main advantage of these other routes is for pediatric patients in whom IV access may be problematic or for procedures that may require only minimal sedation in conjunction with the use of local anesthetics. These routes are also advantageous for simple sedation during diagnostic imaging.

With the exception of ketamine, agents administered intramuscularly have erratic absorption and a variable onset of action. Accordingly, prolonged preprocedural and postprocedural observation may be necessary. When required, the IM route offers little advantage over oral or transmucosal administration.

Another PSA route is via inhalation of nitrous oxide. This gas can either be delivered by a demand-flow system using a handheld mask or be delivered to young children using a nose mask in a continuous-flow system under close clinician supervision.

Because individual needs may vary widely, the application of arbitrary ceiling doses of analgesic and sedative regimens is unwarranted. The true ceiling dose of an agent is the level that provides adequate pain relief or sedation without major cardiopulmonary side effects such as respiratory depression, apnea, bradycardia, hypotension, or allergic reactions.

There are two absolute contraindications to PSA: severe clinical instability requiring immediate attention and refusal by a competent patient. Relative contraindications include hemodynamic or respiratory compromise, altered sensorium, or an inability to monitor side effects (e.g., magnetic resonance imaging [MRI] without remote monitoring). However, even in many of these circumstances, appropriate agents can be given to provide analgesia and sedation while minimizing the chance for further deterioration. Although safely sedating patients at the extremes of age is challenging and requires additional care, as well as reductions in drug dosing (because of decreased drug metabolism and excretion), age is not a contraindication to PSA.

Drug Selection Strategies

The majority of nonpainful or minimally painful ED procedures in older children and adults can be performed without systemic sedation and analgesia. Skilled practitioners can frequently combine a calm, reassuring bedside manner with distraction techniques, careful local or regional anesthesia, or both.62–64 Many procedures, however, cannot be technically or humanely performed without PSA. These situations can be divided into three categories.

Insufficient Analgesia.: Despite a cooperative patient, for some procedures it is impossible to achieve effective pain control with local or regional anesthesia. Examples of procedures requiring systemic PSA include fracture reductions, dislocation reductions, incision and drainage of large loculated abscesses, wounds that require scrubbing such as “road rash,” cardioversion, bone marrow aspiration/biopsy, and extensive burn débridement.

Insufficient Anxiolysis.: Despite effective local or regional anesthesia, some patients will be so frightened that procedures cannot be technically or humanely performed without PSA. Young children requiring repair of lacerations are frequently terrified, and older children and adults may be highly anxious in anticipation of such repairs in sensitive or personal regions (e.g., face, genitalia, perineum).

Insufficient Immobilization.: Despite effective local or regional anesthesia and anxiolysis, PSA may be indicated to prevent excessive motion during procedures that require substantial immobilization (e.g., repair of complex facial lacerations, diagnostic imaging studies). Immobilization is most commonly an issue with young children and the mentally challenged.

General Considerations.: Clinicians must therefore base customization of their selection of drugs (e.g., anxiolysis, sedation, analgesia, immobilization) on the unique needs of the patient and their individual level of experience with specific agents (Table 33-4). A risk-benefit analysis should be performed before every sedation (Box 33-4). The benefits of reducing anxiety and controlling pain should be carefully weighed against the risk for respiratory depression and airway compromise. Factors influencing the extent of pharmacologic management are listed in Box 33-5. Some general drug selection strategies are discussed later and shown in Table 33-3.

Box 33-4

Risk-Benefit Analysis for PSA

• Why is PSA needed in the first place? Is the procedure very painful, frightening, or requiring extreme cooperation?

• Are the risks of PSA appropriate for the procedure involved?

• If a child, do the parents or guardian consent to the use of PSA?

• How long will the procedure take? If it is a short procedure, is it worth the added risk and expense to the patient? If it is a longer procedure, is there an appropriate agent that can be titrated to allow adequate PSA throughout the entire length of the procedure?

• Are there significant side effects that limit a particular drug’s usefulness?

• Are enough nurses and support personnel present to safely allow the use of PSA?

• What is the recovery period for a given agent? Are there enough treatment areas and staff in the ED to allow adequate observation during recovery?

• When did the patient last eat? Is a delay in waiting for a sufficient fasting time worth the time lost in performing the procedure?

ED, emergency department; PSA, procedural sedation and analgesia.

From Krauss B, Brustowicz R, eds. Pediatric Procedural Sedation and Analgesia. Philadelphia: Lippincott, Williams & Wilkins; 1999:294.

Box 33-5 Factors Influencing the Extent of Pediatric Pharmacologic Management

Age

Selected drugs and routes of administration have age limitations and are not recommended above or below a certain age (e.g., demand-flow nitrous oxide in children <5 years, nasal and rectal routes of administration in children >6 years).

Time of Day

A toddler seen at naptime or at 9 pm who is tired and sleepy will usually require smaller dosing and possibly a lower level of PSA than required at 9 am. Young children with facial lacerations at night, after their normal bedtime, may require only topical anesthesia and a quiet room for 20 to 30 minutes to achieve a painless laceration repair while the child sleeps.

Fasting Status

Young children can be extremely difficult and uncooperative when hungry, tired, or both. In anticipation of PSA, many children are kept without oral intake from the time that they are triaged in the ED. This can further increase hunger and irritability, especially if the child waits 1 to 2 hours to be seen by a clinician.

Availability of Staffing and Equipment

Staffing availability can affect the use and timing of sedation and is especially important in busy EDs with multiple sedations occurring concurrently and in smaller units that are set up for only one sedation at a time.

Location of the Injury

Injuries located in areas of cosmetic concern (especially on the face) or near sensory organs (e.g., ears, eyes, mouth, nose) will often require a high degree of agitation control and a concomitant level of PSA.

Previous Medications

An accurate history of previous medication administration is important in situations in which a child is referred from another facility because this can affect the type and timing of PSA agents that can be given. In particular, a child may have received opioids or sedative-hypnotics before transfer and may still be sedated on arrival, thus necessitating an adjustment in the PSA regimen.

Level of Anxiety

The level of anxiety of both the child and the accompanying adult or adults must be accurately assessed. Children manifest anxiety in many different ways, and emergency clinicians must be facile at recognizing the varying expressions of anxiety, especially in young children. A child with a facial laceration quietly sitting on the stretcher during the initial examination will not necessarily be a calm and cooperative patient during repair of the laceration (infants and toddlers). The nursing assessment at triage of the state of the child and accompanying adult or adults can be very helpful in some cases in determining the need for PSA. A child who was frightened and uncooperative in triage may be calm and compliant during a procedure. Unfortunately, the reverse is also true. When confronted with an extremely anxious child, ED personnel should ascertain what the parents have told the child about the upcoming procedure. Many parents, in the hope of lessening their child’s anxiety, will tell the child that she or he will get a “shot” or a “needle” and that the procedure will “only hurt for a minute.” This type of parental preparation, especially in young children who do not have the cognitive ability to mediate their anxiety, often results in a significant increase in the child’s anxiety and a decrease in the child’s ability to cooperate, especially if the child has had a previous negative experience with a procedure in the ED. It is also important to assess the parents’ level of anxiety because this will determine the degree to which they can assist during the procedure. An extremely anxious parent or a parent who must take care of other siblings during the procedure will find it difficult to assist in distracting the child or otherwise helping the child cope with the procedure.

Previous Experience

Children’s previous experience in hospitals can greatly affect their response to the current situation. Direct experience is not the only way to create anxious, frightened, and uncooperative patients, though. Images from television, stories from peers, or previous witness of a sibling being forcibly restrained for repair of a laceration can leave a powerful and lasting impression. This type of influence should be especially suspected in children whose anxiety seems out of proportion to the present situation. Eliciting from the parents a history of a previous difficult experience in the ED can be a decisive factor in determining the degree of sedation required. Children who have had a recent unpleasant laceration repair and who now have a new laceration may well require PSA as opposed to simple anxiolysis (either pharmacologic or nonpharmacologic) had there been no previous trauma.

Child’s Behavior at Routine Primary Care Visits

Inquiring into how a child behaves during routine primary care visits can yield important information on how the child reacts to stressful situations, how cooperative the child will be with the anticipated procedure, and whether pharmacologic management is needed. Children who cry but hold still when vaccinated may be more compliant than children who are described by their parents as being “afraid of doctors” or “wild” during visits to the primary care physician.

ED, emergency department; PSA, procedural sedation and analgesia.

TABLE 33-4

Indications for PSA and Sedation Strategies *