In 2001, the Joint Commission developed a new definition of moderate sedation that is now widely accepted and used. The Joint Commission identifies moderate sedation/analgesia as the second level in a continuum between minimal sedation (i.e., anxiolysis) and deep sedation (i.e., anesthesia). Thus, the Joint Commission defines moderate sedation/analgesia as "a drug-induced depression of consciousness during which patients respond to purposefully 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" [1]. The Joint Commission has mandated that an institution's sedation practices be monitored and evaluated by the department of anesthesia. In response to this mandate, the American Society of Anesthesiologists (ASA) developed practice guidelines for nonanesthesiologists who provide sedation and analgesia [2,3,4]. The practitioner should recognize that sedation is part of the continuum that progresses from minimal to moderate to deep sedation and eventually reaches the state of general anesthesia. Each individual patient should be closely and continuously monitored to prevent this progression to the deeper sedated states [5]. Practitioners of sedation should have the necessary skills to rescue a patient from a deeper level of sedation than that intended [5].

Moderate sedation/analgesia can be used to achieve a number of objectives. Moderate sedation allows a patient to tolerate an unpleasant procedure while maintaining consciousness and cooperation. Many of the pharmacologic agents used will provide mood alteration and partial amnesia. The patient does not remember the majority of the procedure and awakens in a comfortable, composed state. The choice of medications used depends on the objectives desired; some medications will provide for an elevation in the patient's pain threshold, while others have no analgesic properties. However, it is important to note that the term moderate sedation cannot be used synonymously with pain management, as not all sedating medications will achieve the parameters of pain control. An additional goal of sedation is a rapid return of the patient to his/her presedation state with a decreased risk of resedation. It is imperative for nurses providing moderate sedation to remember that while the goals and objectives of moderate sedation are important, the most critical part of patient care delivery is providing for patient safety during the time that the patient is sedated and recovering from sedation.

Airway assessment should be conducted and is easily performed using the modified Mallampati scale[26,27,28]. The patient is placed in a comfortable sitting position and asked to open his/her mouth and protrude the tongue. The nurse then assesses the airway, noting the ability to visualize the fauces, anterior and posterior pillars, soft palate, and uvula. The patient with a Class 1 airway has all these structures visible. The pillars are masked by the tongue in a patient with a Class 2 airway. A patient with a Class 3 airway has only the soft palate and base of the uvula visible. A patient for whom only the hard palate is visible has a Class 4 airway[29]. The modified Mallampati scale allows the nurse to recognize which patients may be at risk for difficult airway management, including difficult intubations[28]. It has also been noted that obesity may contribute to airway difficulties[30,31]. In addition to visualization of the airway, neck circumference and body mass index should also be assessed preoperatively and considered in the overall airway assessment.

Finally, the setting in which sedation will be administered should be considered in the selection process. The ASA Committee on Standards and Practice Parameters recommends that patients who receive moderate sedation on a scheduled basis should not drink clear fluids for at least two hours or eat solid foods (a light meal) for at least six hours prior to the procedure[32]. However, meeting the fasting requirements for emergently performed procedures is difficult, and guidelines note that when urgent or emergent procedures must be done, recent food intake is not a contraindication for administering procedural sedation/analgesia in adults or children[3,4,23,33,34]. The potential risks of sedation without fasting (e.g., aspiration) should be weighed against the benefit of performing the procedure promptly[4]. The ASA has developed a Physical Status Classification System to determine risk for complications among patients undergoing anesthesia (Table 2). This scale is frequently used in the moderate sedation setting and easily performed on all patients in all settings. Patients in Class 1 and 2 are considered good candidates for moderate sedation procedures; those in Class 3 and Class 4 carry higher risks. Nurses providing sedation should recognize that Class 3 and 4 patients may benefit from sedation and should not be excluded based upon their ASA classification. Sedation is frequently provided to ICU patients, most of whom are in Class 3 or 4, and these patients greatly benefit from the effects of the sedation.

During sedation, the patient will be monitored for his/her response to the medications used. If a patient demonstrates restlessness and agitation, the nurse should determine the cause and intervene to reverse any untoward events. Restlessness and agitation should always be considered signs of hypoxemia until proven otherwise. However, it is just as possible that these behaviors are secondary to inadequate analgesia, and further assessment should be performed. If the nurse considers hypoxemia as the primary cause and intervenes appropriately, the risk of further hypoxemia is eliminated.

Typical discharge criteria require that the patient return to his/her preprocedural status. The patient should have adequate respiratory function and stable vital signs. The preprocedural level of consciousness should be reached, without the risk of resedation and a return to a decreased level of functioning. Intact protective reflexes, including gag reflex, are imperative. The patient should have his/her pain under control, and the procedural site should be stable, without evidence of bleeding or other complications. Many facilities also delineate a time period since last receiving medications as a parameter for discharge. Finally, if a patient is to be discharged to home, a responsible adult caregiver should be present to accompany the patient[39,45]. If the patient is a child who still uses a car seat, the American Academy of Pediatrics (AAP) suggests that at least two adults be available to take the child home, so one adult can sit with the child while the other drives[33]. Parents should be told that the child is at risk for airway obstruction if his or her head falls forward while in the car seat[45].

The ideal moderate sedation agent should be one that is rapid acting with limited cardiorespiratory effects. A titratable medication would allow the practitioner to administer drugs in which the length of action is equal to the length of time required for sedation. Providing both analgesia and sedation would be beneficial in many situations and for many procedures. Furthermore, this ideal agent would be eliminated expeditiously for rapid return to the presedation state. And if complications were to occur, a drug that is readily and easily reversed would be optimal.

Transmucosal and intravenous moderate sedation produce sedation in the patient through somewhat different pathways. Most commonly, transmucosal administration includes oral, sublingual, and rectal administration. Other forms of administration include intramuscular, inhalation, subcutaneous, and topical administration. Intravenous sedation will be addressed separately.

Administering medications via the intramuscular route is often rejected by patients, if given the choice. Intramuscular injections can cause pain and irritation of the tissues. Intramuscular absorption is dependent on blood flow to the muscle, and the onset of sedation can be quite rapid if blood flow is adequate. However, if blood flow is compromised, onset is slow and length of action may be prolonged as the drug stays sequestered in the muscle and is slowly released. Despite these disadvantages, certain medications, such as ketamine, are being administered more frequently by this route. One complication of intravenous ketamine use is emergence excitement, the incidence of which is greatly reduced with intramuscular or oral administration [59]. Emergence reactions also may be reduced by pretreatment with a benzodiazepine, use of ketamine at the lower end of the dosing range, and minimizing verbal and tactile stimulation of the patient during the recovery period [60].

The major effect of these drugs is on the respiratory system of the patient. The patient may develop a depressed ventilatory response to increasing carbon dioxide levels with subsequent falling levels of arterial oxygenation. Each 0.1 mg/kg of midazolam is said to reduce the body's response to rising carbon dioxide levels by 50%. In addition, there is a rise in pulmonary airway resistance. As the patient's level of consciousness decreases, the risk of respiratory insufficiency increases greatly [67,68].

Midazolam is a drug that is easily administered by a number of routes (i.e., intramuscularly, orally, rectally, intranasally) [72]. Intravenous administration provides rapid onset of action (i.e., three to five minutes), with a duration of less than two hours. It is easily titrated and associated with less pain at the injection site [60,72]. Intranasal midazolam has become popular as a method of achieving moderate sedation in the pediatric population, although this is an off-label use [60,72,73]. This method may also be used to achieve initial sedation in a child prior to insertion of an IV line. Additionally, midazolam can be administered by continuous infusion. The loading dose is 0.5–2.0 mg/kg over two minutes, which may be repeated every two to three minutes, if needed, for a total dose of no more than 5 mg [60].

Chest wall rigidity is an uncommon, but life-threatening, complication that can occur with the rapid intravenous administration of narcotics, especially fentanyl. The chest wall muscles become tight, and the patient is unable to be ventilated. To successfully resuscitate the patient, the administration of succinylcholine should be performed rapidly and the patient ventilated with a bag-valve-mask device until the respiratory drive returns. Additionally, naloxone should be administered to combat the effects of the narcotics and repeated if necessary. Obviously, with this development, the goals and objectives of moderate sedation are no longer being met and other actions should be undertaken if the procedure is to be continued [58].

The peak effect of propofol can be achieved within one minute and lasts four to eight minutes; thus, the drug is administered by continuous infusion [60]. It is important to remember that special handling of the drug is required to prevent the risk of multi-system sepsis. Propofol is available as an oil-in-water emulsion that contains egg lecithin, glycerol, soybean oil, and very small amounts of preservative. It is recommended that the drug be used and completed within 6 hours if transferred to a syringe or other container prior to administration, and 12 hours if used directly from a vial or prefilled syringe. When preparing the drug, strict aseptic technique should be used [60]. The vial top should be disinfected with 70% alcohol, a sterile vent spike should be used to withdraw the drug, and the medication should be drawn up into a sterile syringe. Once drug administration is completed, the IV solution and IV tubing should be discarded and replaced with new solutions. If the drug is used for continuous sedation (e.g., as used in an ICU), it is recommended that the IV line and solution be changed every 12 hours [60]. Any patient who receives prolonged sedation with propofol should be monitored for developing signs of infection [60].

In the emergency department setting, intravenous administration of ketamine is preferred for adults because of the ease of repeated doses and reduced risk for vomiting [98]. In the event of an inadvertent overdose, no antagonist exists and the effects cannot be reversed [99].

Pulse oximeter probes may be placed in a number of locations, including the fingers, toes, earlobes, nose, or forehead. Repetitive research studies have evaluated pulse oximetry monitoring and the results consistently demonstrated that the probes placed on the patient's earlobe are more accurate and have faster response times than probes placed elsewhere[105]. With this in mind, the practitioner should assess the earlobe site for use in probe placement. In certain procedures, as when the patient's head is draped, this location would not be considered appropriate. Proper positioning of the oximeter probe is essential to prevent production of artifactual data (e.g., underestimation or overestimation of oxygen saturation)[5].

End-tidal CO₂ monitoring measures expired carbon dioxide and provides information about the patient's ventilation. This type of monitoring is most commonly used with deep sedation and general anesthesia but is becoming commonplace in monitoring patients undergoing moderate sedation [110]. The advantage of this type of monitoring is that it allows early detection of developing hypoventilation and possible airway obstruction. Additionally, if the patient is developing the early stages of malignant hyperthermia, this can be recognized by rising CO₂ levels.

Placement with modified chest lead using V1 (MCL1) produces a waveform that is normally negative; however, with right bundle branch block, the waveform will be upright. Many practitioners do not feel comfortable with this waveform view and therefore have difficulty in recognizing cardiac developments such as ischemia and/or arrhythmias. MCL1 placement requires that the positive electrode be placed in the fourth intercostal space to the right of the sternum. The negative electrode is placed below the left clavicle in the midclavicular line. The ground electrode may be placed in any convenient position [121].

The major advantage of monitoring the patient in MCL1 is that right and left bundle-branch block may be easily identified. Additionally, differentiation of ventricular tachycardia and supraventricular tachycardia with aberrancy is possible [121]. Premature ventricular contractions can be evaluated to determine their origin, either in the right or left ventricle. MCL1 is used frequently in intensive care units as it is equivalent to lead V1 on the 12-lead electrocardiogram. However, it has been shown to differ in QRS morphology in 40% of patients with ventricular tachycardia and is, therefore, not recommended for diagnosing wide QRS complex tachycardia [121].

Additionally, recognition of myocardial ischemia formation can allow the practitioner to determine if developing ischemia and myocardial injury is occurring. T-wave inversion is seen first with myocardial ischemia. The patient subsequently develops tall, peaked T waves, which are asymmetrical with a wide base. The ST segment becomes elevated, indicating myocardial injury. At this point, the extent of long-term myocardial damage can be reversed with oxygen and nitrate therapy. The development of Q waves can occur at any time, within a few hours or up to days after the infarct. The practitioner monitoring the patient receiving sedation can use the cardiac abnormality to determine the extent of ischemia, and consequently, a decision can be made regarding the necessity of discontinuing the procedure or correcting the ischemia (e.g., with oxygen therapy, nitrates).

The bispectral index (BIS) has been developed as a method of objectively determining sedation status via electroencephalogram (EEG) recordings [125]. Based on the index, the sedation level can be determined mathematically based on the patient's EEG pattern. An alert adult would receive a score of 100, while a score of 0 is characterized by an isoelectric EEG pattern [125]. The bispectral index score is a relatively new tool, and research has indicated that it is a valid measure of depth of sedation, in addition to nursing evaluation [45,126,127,128]. However, some studies have found its use to be questionable among some populations, such as pediatric patients, and both the ACEP and the ASGE have found insufficient evidence to recommend routine use of BIS [4,56,63,129,130,131].

The ideal flow sheet should have three basic sections: the presedation assessment, the intrasedation record, and the postsedation record, which includes the discharge status of the patient. The format of the flow sheet should allow a reviewer to easily determine how the patient responded to therapy and sedation. Graphic flow sheets, which allow for vital sign charting next to medication administration times, allow rapid assessment of the patient and the patient's responses to medications [132].

Certain populations are at increased risk of oversedation and undersedation, particularly the young, the old, the critically ill, and the obese [3]. Patients with liver and/or renal disease are also at increased risk, especially for oversedation [136]. Patients with high preprocedural levels of anxiety may also be at risk; the heightened anxiety state can prevent the patient from achieving the full benefits of the drug administered. As an example, a patient with a high level of anxiety is scheduled for an MRI. The patient has heard a great deal from friends and family about the claustrophobic environment of the scanner. This patient has a fear of enclosed spaces and becomes fearful that he/she will be unable to tolerate the closed-in feeling in the scanner. The nurse caring for this patient administers a low-dose benzodiazepine in an effort to relax the patient and relieve his/her anxiety. The preprocedural instructions provided to the patient explained the type of sedation and that these medications are administered to relieve the patient's heightened level of anxiety. However, the dosage administered is inadequate to achieve these goals, and the patient enters the scanner without feeling relief. The patient believes that the medication should be working but remains unable to relax. This only further increases the patient's anxiety, and the physiologic responses of an increased heart rate and blood pressure become evident.

Aspiration is the most common cause of death secondary to intravenous moderate sedation [6]. Although the risk of death is increased, the incidence of aspiration remains lower in moderate sedation than in general anesthesia [139]. The most common cause of aspiration is the relaxed cardiac sphincter tone that develops with deeper levels of sedation. Any patient with a history of reflux is at risk, as are obese, obstetric, and elderly patients [6,24,56].

Hemodynamic instability is a common cardiovascular complication occurring during moderate sedation [6]. The direct cardiodepressant effect of many of the sedating drugs causes hypotension in the patient. The patient with a pre-existing compromised circulatory volume is at greatest risk for this complication [56]. Hypovolemia and hemorrhage require aggressive volume and blood replacement to prevent dangerously low circulating pressures. In acute cases, vasoactive drugs may be required to supplement hemodynamic status. Recognition of the patient at risk for hypotension will allow the practitioner to supplement the patient's volume status prior to sedation, thereby circumventing this problem. Hypotension may be an early sign of oversedation.

The onset of symptoms of MH may begin with the development of masseter muscle spasm (also known as masseter muscle rigidity) and rising CO₂ levels. The patient can develop tachycardia and other ventricular dysrhythmias [141,146]. The patient's core temperature remains normal in the early stages; however, the skin appears flushed and may feel warm to touch. It is imperative that the care provider recognize these symptoms in this early stage. If the syndrome progresses to the state of high fever and muscle rigidity, the incidence of death and long-term sequelae increases [141].

Finally, the risk of paradoxical reaction exists. The patient who experiences agitation, dysphoria, and/or confusion, either during sedation or upon recovery, is at risk for self-inflicted injury. These types of reactions are more common in the pediatric and elderly populations and are known side effects of certain medications (e.g., midazolam use in the elderly, benzodiazepine use in children) [148]. If a paradoxical reaction to benzodiazepines is suspected, the offending agent should be discontinued immediately. While management with observation may be sufficient, tranquilization (e.g., with low-dose ketamine, propofol, haloperidol) has been reported to be successful [149].

One of the major complications of aging and the use of moderate sedation occurs when benzodiazepines and/or opiates are used. Both of these drug classes produce enhanced depression of the patient's respiratory drive, which is a normal change that occurs with aging. With rising levels of CO₂ and falling levels of oxygenation, the younger person will increase the depth and rate of respirations to ensure adequate tissue oxygenation. This ability to respond to these changes is dampened in the elderly, putting the individual at risk for profound hypoxemia [159]. Concurrently, the blood oxygen levels decrease with age; it is not uncommon for the elderly individual to have blood oxygen levels of 80 torr with oxygen saturations of approximately 93% to 95% [159]. These compounded problems lead to a patient who is at increased risk for hypoxia and hypercapnia, which requires judicious monitoring to prevent their occurrence.

Drug binding is also altered in the elderly patient. Protein-bound drugs attain an increased concentration of circulating drug secondary to the decrease in albumin that occurs with aging [160]. With more circulating drug available, the more profound the drug effects will be. Hence, any sedating drug that is protein bound will produce more profound sedation, increasing the risk of oversedation. The amount of body protein in an individual can be assessed by evaluating the patient's serum albumin level. The lower the albumin level, the lower the amount of body protein. Any patient with a decreased serum albumin would be expected to have the aforementioned risk of profound sedation.

Presedation vital signs and oxygen saturations should be attained, noting that anxiety and fear may cause these to be inaccurate. Once these parameters are attained, oxygen should be administered, with consideration of the patient with a history of pulmonary disease, which may preclude the use of high oxygen percentages. Cardiac monitoring should be instituted prior to sedation and continued throughout the sedation and recovery periods. Volume replacement may be necessary; however, it is just as important to prevent volume overload in the patient with a positive cardiac history. It is also important to remember that the elderly patient is at risk for developing hypothermia, and the patient should be kept warm during long procedures, especially those interventions with large body surface exposure.

Airway changes in the pregnant woman include engorgement of the nasal and mucous membranes leading to a narrowing of the airway. Tidal volume increases by 30% to 35%. The respiratory rate remains relatively constant or increases slightly. In order to meet her and her fetus's oxygen demands, there is a compensatory and significant increase in minute ventilation. However, the patient's vital capacity decreases as the diaphragm becomes elevated [163].

Hemodynamic changes occur during pregnancy as well. There is an increase in heart rate, which reaches a maximal value of 10% to 30% above baseline values by 32 weeks. Cardiac output increases 30% to 50% above baseline levels by 25 weeks and may be affected by position [163]. Systolic blood pressure may drop, and the patient is at risk for developing supine hypotension [163]. It is imperative that the practitioner be aware of these changes as assessment parameters are altered and the recognition of hemodynamic instability is more challenging [164].

Additionally, contrast dyes may have high sodium levels that produce a transient hypertensive period, usually followed in 15 to 20 minutes by a diuretic phase. Furthermore, during this time the patient has an increase in cardiac filling pressures. For the patient with a compromised cardiovascular system, these changes in vital signs and cardiovascular volume may not be well tolerated. It is imperative that the practitioner continually monitor these patients and intervene, should the effects be detrimental and/or lengthy in the patient.

In determining the nurse's scope of practice in regards to sedation administration, a number of resources should be accessed. The State Board of Nursing should be consulted as to nurses' legal scope of practice [177]. The State Boards of Nursing in all 50 states address the administration of moderate sedation, and it is imperative that the nurse be aware of these legal limitations. Some Boards of Nursing have developed fairly stringent guidelines for sedation administration. Others have more loose definitions of nurses' responsibilities that allow the nurse and the institution to develop their own policies regarding drug delivery.

Definitions

One standard of care that is critical to safe drug delivery is that the physician be physically present in the room prior to drug administration. Many institutions neglect to spell out this requirement, and the nurse is asked to administer sedation without appropriate backup personnel. As an example, a physician telephones the endoscopy suite and orders the nurse to administer 5 mg IV midazolam, informing the nurse that he/she would like the patient sedated and ready to begin the procedure when he/she arrives in three to four minutes. The nurse may administer the drug as ordered; however, the physician may be inadvertently delayed by a telephone call, a stuck elevator, or for any number of reasons. The nurse is now caring for a sedated patient without sufficient backup. If the policy states that the medications will only be administered once the physician is present, this risk will be avoided. The Joint Commission requires that, in addition to the individual performing the sedation procedure, sufficient numbers of qualified staff be present to evaluate, monitor, administer medication, assist with the procedure, and recover the patient, if needed [25].

The more comprehensive the policies and procedures, the better protected the facility and nursing staff is from legal action, should a problem arise. The policies will allow the nurses to deliver safe care before, during, and after the procedure. The policies and procedures should be updated on an annual basis to ensure compliance with changing standards of care and standards outlined by changing Nurse Practice Acts and Joint Commission requirements.

If a patient receives medications by the transmucosal route, does that patient require a patent IV line or heparin lock? Or, should the patient be cared for by someone with IV skills? Flumazenil, the benzodiazepine antagonist, should be administered intravenously. If a patient receives transmucosal midazolam, as an example, and requires an antagonist and no line has been placed, the administration of this drug is delayed while IV access is secured. Therefore, any patient receiving moderate sedation should have a patent IV line, regardless of the method of original administration.

Is the length of observation time shorter (or longer) for patients receiving transmucosal medications? Many individuals inappropriately believe that if a patient receives transmucosal medications, their recovery time is shorter. In fact, the length of action of the drug may be longer due to slower absorption.

Can individuals who receive transmucosal medications go home earlier than patients receiving intravenous medications? Can they drive themselves home and go home alone? Do they need the same type of discharge instructions as does the patient receiving intravenous medications? The answers to these questions are well accepted if the patient receives intravenous medications. There are well-developed standards of practice for intravenous drug delivery. The nurse administering sedation by the transmucosal route should answer these questions prior to drug delivery.

One of the most important things to remember is: What are the goals and objectives of moderate sedation? If the goals and objectives are the same whether the patient is receiving the sedation by the intravenous or the transmucosal route, is there a difference in care? It is definitely a point to ponder and one that should be answered by the individual and the institution and delineated in the policy and procedure for moderate sedation.

Competency verification is a critical part in the delivery of safe patient care. A mechanism for the evaluation of the nurse's skills and knowledge should be an integral part of the moderate sedation program. Areas for moderate sedation competency evaluation include [6,176]: