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Sedation of the Pediatric Patient
Robin Kaye
Imaging pediatric patients provides many interesting challenges, not the least of which is keeping them motionless for the studies. Almost any imaging study is degraded, to a greater or lesser degree, by patient motion, and this can be particularly true for nuclear medicine studies where spatial resolution is an issue. Unfortunately, even the most coop- erative child often cannot hold still for an imaging study of any length.
This means that adequate sedation is one of the most important factors in performing high-quality imaging studies in children. This chapter discusses some of the basic concepts in pediatric sedation and suggests an approach to providing safe and effective sedation of children who are referred for PET scanning.
Background
In 1992 the American Academy of Pediatrics (AAP) revised its Guidelines for Monitoring and Management of Pediatric Patients During and After Sedation for Diagnostic and Therapeutic Procedures (1) and defined the goals of safe pediatric sedation. Other organizations, such as the American Society of Anesthesia (ASA) and the American College of Radiology (ACR), have also written such standards. In 2002 the ASA revised its practice guidelines for sedation and anesthesia by nonanesthesiologists (2), and in 2005 the ACR revised its guidelines for sedation of pediatric patients (3). The Joint Commission on Accreditation of Healthcare Organizations has adopted the concepts provided by the AAP guidelines, which has become a template for institutional policies and procedures for pediatric sedation in hos- pitals throughout the United States (4). The primary goal for sedation in the pediatric patient, as defined in these guidelines, is to guard the patient’s safety and wellness in order to avoid sedation accidents.
In addition to patient safety, successful sedation of pediatric patients also has the goals of minimizing physical discomfort or pain, control- ling behavior, minimizing negative psychological responses, and
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returning the patient to a state in which safe discharge is possible. All clinicians and support staff involved in the sedation of pediatric patients should understand and follow these guidelines. Further, it is highly advisable that, in order to ensure safe sedation of the pediatric patient undergoing imaging, a unified approach should be used in the radiology department and indeed throughout the entire institution (2,5–9) to help avoid errors that could potentially lead to sedation accidents.
To ensure that each of these goals is accomplished, several steps must be taken. First, the patient’s present and past medical and surgical history must be thoroughly evaluated to find any possible problems that could affect sedation (Table 2.1).
Second, the patient should be fasting from solids (including formula or milk), breast milk, and clear liquids for an adequate period of time.
Neonates and infants under 6 months of age should be NPO (nothing by mouth) for 2 hours for clear liquids, for 3 hours for breast milk, and for 4 hours for solids. Patients from 6 to 36 months of age should be NPO for 2 hours for clear liquids, for 3 hours for breast milk, and for 6 hours for solids. Patients over 36 months of age should be NPO for 2 hours for clear liquids and for 6 to 8 hours (at the physician’s dis- cretion) for solids. This regimen is recommended to decrease the risk of aspiration during sedation (Table 2.2). The only exception to these guidelines should be for those patients who require an oral medication, such as an antiseizure drug. These drugs are given prior to the proce- dure with small sips of water or other clear liquid at least 2 hours prior to the procedure.
Third, the sedation should be planned ahead of time, ideally based on a sedation protocol that includes a drug formulary that is compre- hensive and appropriate for children of all ages and conditions. The appropriate sedative agents should be selected and doses calculated on a milligram per kilogram (mg/kg) basis, with a full understanding of
Table 2.1. Risk factors for sedation
Respiratory Pneumonia, chronic lung disease, asthma tracheo- or bronchomalacia, sleep apnea, mediastinal mass Cardiovascular Cyanotic heart disease, congestive heart failure (CHF),
hypotension, cardiomyopathy Neurologic Seizures, central respiratory depression
Gastrointestinal Gastroesophageal reflux disease (GERD), hepatic dysfunction/failure
Genitourinary Renal dysfunction/failure, dehydration, electrolyte disturbances
Systemic/other Sepsis, allergies, medications, low hemoglobin Syndromic Macroglossia, micrognathia, chest wall deformity,
craniofacial deformity scoliosis
their pharmacokinetics and pharmacodynamics. The selected agents should be titrated to effect, and sufficient time should be allowed to elapse between doses to achieve peak drug effect before administration of additional drugs. The doses of any pertinent reversal drugs should also be calculated ahead of time, although it is not necessary to have them drawn up for the procedure.
Fourth, if sedations are going to be performed, it is imperative to have high-quality monitoring equipment appropriate for all ages and sizes of children and an adequately trained group of sedation nurses with the knowledge and skills to properly monitor the patient during drug administration and during the procedure. Patients should also be monitored postprocedure to ensure that they are fully recov- ered from the effects of sedation before being released from medical supervision.
Fifth, there must be readily available resuscitation carts with med- ications and a full range of functioning age- and size-appropriate equipment, such as laryngoscopes, endotracheal tubes, oral airways, bags, and masks, to manage emergencies. One further precaution is the need for staff members to recognize their own limitations in expe- rience and expertise; in those instances when the experience and exper- tise of the available staff are not sufficient, it is prudent to reschedule the examination for sedation by an anesthesiologist or other sedation specialist (Table 2.3).
Table 2.2. Risk factors for pulmonary aspiration of gastric contents History of recent oral intake
Extreme obesity Pregnancy
Patients with abnormal airway anatomy Neurologic disorder
Neurologic dysfunction Head trauma
Deceased level of consciousness Gastrointestinal disorders
Bowel motility dysfunction Esophageal dysfunction Gastroesophageal reflux Gastrointestinal obstruction Prior esophageal surgery
Previous administration of pharmacologic agents Drugs that decrease gastric motility
Drugs that produce loss of consciousness or depressed level of consciousness
Drugs that produce loss of or reduce protective airway reflexes
Levels of Sedation
Sedation is on a continuum from consciousness to unconsciousness and is a dynamic process. In children, in particular, progression along this continuum can be imperceptible and rapid, and may not depend so much on actual drugs and dosages but rather on individual responses.
Because the level of sedation prescribes the intensity of monitoring, the team performing the sedation must be prepared to assess the true level of sedation and be prepared to increase the level of monitoring accordingly. There are three commonly described levels of sedation:
conscious sedation, deep sedation, and general anesthesia. The differences between each of these levels should be well understood (Table 2.4).
Conscious sedation is defined as a medically controlled state of depressed consciousness in which protective reflexes are maintained, including the ability to maintain a patent airway and the ability of the patient to respond appropriately to verbal or physical stimuli. A true state of conscious sedation can be very difficult to attain in children. In our experience, most children require a deep level of sedation during procedures. Observation and monitoring of the pediatric patient who is medicated for conscious sedation includes continuous pulse oxime- try, heart rate, intermittent respiratory rate, and blood pressure moni- toring by a trained observer who frequently evaluates the patient but who may also participate in the procedure.
Table 2.3. Circumstances that may require the assistance of an anes- thesiologist or other specialist in sedation
Patient factors
ASA class III or higher
History of severe emotional or psychiatric illness History of major allergy or anaphylactic reaction Morbid obesity
Sleep apnea Pregnancy
Chemotherapy-induced cardiomyopathy Anatomic airway abnormalities
Life-threatening underlying medical/surgical conditions History of difficult sedations
Patients with a full stomach
Patients with significant cardiac, pulmonary, renal, or central nervous system (CNS) dysfunction
Procedural factors Prolonged sedation Complex procedure New procedure Emergency procedure
Procedure and patient suitable for regional block
Procedure carried out in unusual position or geographic location Miscellaneous factors
Skilled personnel not available Inadequate facility or equipment
As compared to conscious sedation, deep sedation is a medically controlled state of depressed consciousness or unconsciousness in which the patient is not easily aroused and does not respond pur- posefully to verbal or physical stimuli and in which the patient may or may not maintain protective reflexes, including keeping a patent airway. In general, sedation protocols commonly used in radiology departments only very infrequently result in airway compromise.
Monitoring for patients under deep sedation is significantly more intense than for those who are under only conscious sedation, as would be expected. The patient must have a working intravenous (IV) line;
pulse oximetry and heart rate are continuously monitored; and vital signs (blood pressure, heart rate, and respiratory rate) are recorded every 5 minutes by an independent practitioner whose sole responsi- bility is to observe the patient’s vital signs, airway patency, and ade- quacy of ventilation. Resuscitation equipment and medications must be readily available.
General anesthesia is a medically controlled state of unconsciousness in which protective reflexes are lost, the airway cannot be inde- pendently maintained, and the patient cannot respond to verbal or physical stimuli. Only specially trained physicians, or nurse anesthetists under their direct supervision, can provide general anesthesia.
The choice of whether to use sedation or general anesthesia is influenced by many factors: the physician’s experience and expertise with sedation techniques and drugs, the ASA status of the patient, the availability of nurses trained in sedation techniques and patient monitoring, the institutional policy regarding sedation, and the length, complexity, and risk of the procedure to be performed. The risk of sedation-related complications increases directly or even exponentially with increasing ASA status (10). In general, patients with ASA I or II status are well suited for IV sedation by a radiology sedation team. Chil- dren with ASA class III status should be carefully evaluated and their condition and attendant risk factors carefully understood by the radiol- ogy sedation team before attempting IV sedation. ASA class IV status patients are most suitably cared for by an anesthesiologist or intensivist.
Table 2.4. Levels of sedation
Conscious sedation Deep sedation General anesthesia
Deep consciousness Deep Unconsciousness
consciousness/
unconsciousness
Protective reflexes Protective reflexes may or Loss of protective maintained may not be maintained reflexes
Patent airway +/- Ability to maintain Inability to
maintained patent airway independently
independently independently maintain patent airway Appropriate Inability to respond to Inability to respond at responses to verbal verbal or physical stimuli all to verbal or or physical stimuli appropriately physical stimuli
In addition, when there is a history of failed sedation, or when extreme patient cooperation is required, general anesthesia should be used.
Approach to Sedation
In our opinion any radiology department doing five or more cases per day that require medication to facilitate quality imaging should con- sider developing a sedation program. Performing that volume of cases using general anesthesia would be extremely challenging because, in our experience, most cases take at least 1.5 hours to complete.
Sedation by a radiology sedation team is preferred whenever possi- ble because it allows easier, faster, and more flexible case planning and preparation and is less costly than general anesthesia. When sedation is chosen, formal protocols for preprocedural, intraprocedural, and postprocedural monitoring of the patient are imperative.
Although it is beyond the scope of this chapter to review all of the possible drugs that may be used, alone and in combination, to sedate children, I would like to describe the approach to sedation used by my department. We have used this method successfully and safely for many years, and although it is not the only approach that can be used, it is a time-tested one that can easily be adapted to use in a variety of settings. We use three main classes of agents for pediatric sedation: anx- iolytics, barbiturate sedatives, and opioid analgesics. It is not impor- tant to know about all of the drugs available in each category. What is important is to choose a few of the drugs from each category and be familiar with their dosing, pharmacokinetics, and pharmacodynamics (e.g., time to peak effect, duration of action, and route of elimination), side effects, interactions with other sedative agents, and reversal agents (if any are available). Having a small, stable formulary that is familiar and predictable enhances the safety and effectiveness of the sedation program.
To successfully sedate children for the purposes of imaging or inter- ventional procedures, the sedation team must carefully create a safe environment. In our opinion, safe and effective sedation facilitated by a team approach requires the presence of experienced pediatric radiol- ogy nurses, and in our practice we work very closely with these nurses.
The radiology nurse is not only involved in obtaining pertinent infor- mation about medical history and physical examination, confirming preprocedure laboratory results, and acting as a liaison with the physi- cians and nurses caring for the patient in the hospital, clinic, or outside facility, but also dispenses sedation medications and monitors and records the patient’s condition during and after sedation. It is these nurses who provide the backbone and consistency for an excellent sedation program. It is our preference to select nurses who have expe- rience in an intensive care unit, pediatric transport, emergency room, or other area that cares for acutely ill children. However, nurses without this experience may also work well on a sedation team if they are trained and mentored to recognize and assess children who
are at risk for problems and complications and take action when necessary.
Our approach to sedation is similar for diagnostic imaging or inter- ventional procedures. As a rule we use single drugs, or two or more drugs in combination, that have the fastest time to action, the fewest untoward effects, and the shortest half-life, so that the return to base- line is as fast as possible. This approach enables us to discharge the patient to home or to the inpatient unit in the shortest time. Also, if untoward effects occur, they are as brief as possible.
We divide patients into two groups based on age: patients 1 year of age or less and patients who are older than 1 year. In children who are 1 year of age or less, the primary sedative is chloral hydrate. This drug may be given either by mouth or per rectum as a suppository. We rarely use the drug per rectum because of its variable absorption and less reli- able onset of action.
In children 3 months of age or younger we usually begin with a dose of 50 mg/kg and in those older than 3 months of age we start with a dose of 75 mg/kg (or 1 g maximum single dose). In either group, the maximum total dose is 100 mg/kg or 1 g. The most common adverse effects of chloral hydrate are respiratory depression and occasionally hypotension. Chloral hydrate has no reversal agent and has a relatively long and somewhat unpredictable time to action, approximately 20 to 30 minutes, which is an obvious drawback. If the patient is not asleep in 20 to 30 minutes after the initial dose, one may want to consider giving a second dose of chloral hydrate or giving a second drug.
Usually the determining factor in clinical practice is whether the patient has a functioning IV in place. Those children without IVs often receive a second dose of chloral hydrate, usually 25 to 50 mg/kg (again with a maximum total dose of 100 mg/kg or 1 g). Those patients who have a working IV may benefit from the addition of either Versed (0.05–0.1 mg/kg) or fentanyl citrate (1 mg/kg) to augment the sedation.
In some cases in this age group, especially for short studies, a combi- nation of Versed and fentanyl alone, given intravenously in the doses mentioned above, can also be used very successfully.
Children older than 1 year are most commonly sedated with a com- bination of intravenous drugs. Because anxiety is very frequently a part of the child’s response to being in the hospital and to imaging studies, we almost always start with a dose of Versed, a benzodiazepine used frequently for anxiolysis, in doses of 0.1 mg/kg (or 3 mg maximum single dose). This drug has the added benefits of creating antegrade amnesia in most patients and of producing mild sedative effects.
We have found that when the patient’s anxiety level is reduced by the use of Versed, the sedation is smoother and the total dose of sedation medication is often less, thereby reducing recovery time, and the overall experience for the patient (and the parents) is much less traumatic.
We administer the Versed 1 to 5 minutes before giving our primary sedative agent. The most common adverse effects of Versed are dose- related respiratory depression and occasionally paradoxical agitation.
Versed can be reversed by flumazenil in doses of 0.01 mg/kg to a maximum of 0.2 mg, but the patient needs to be carefully observed for re-sedation.
Our primary sedative agent is pentobarbital sodium (Nembutal). We use 3 mg/kg (or 100 mg maximum single dose) with a fast IV push as our initial dose. Although pentobarbital is an excellent and safe seda- tive, it has the undesirable property of creating hyperesthesia, and it has a long half-life leading to a relatively long time to return to pre- sedation baseline. The most common adverse effects of pentobarbital are respiratory depression and occasionally emergence delirium. Pen- tobarbital has no reversal agent. To reduce the hyperesthesia effect and potentially reduce the total dose of pentobarbital needed, fentanyl citrate, a short-acting narcotic, can be added in doses of 1 mg/kg (or 50 mg maximum single dose) within minutes of giving pentobarbital.
The most common adverse effects of fentanyl are respiratory depres- sion and transient hypotension. Fentanyl can be reversed by naloxone in 0.01 mg/kg for children and 0.4 to 2 mg for adults, repeated as nec- essary, but the patient needs to be carefully observed for re-sedation.
With this combination of three drugs, the vast majority of children will be sedated adequately to perform the diagnostic imaging study that is planned. If, after these drugs are initially administered the child is still moving, more drug or the addition of another drug is needed. The drug selected depends on the clinical state of the child. If the child is awake (eyes open, talking) a repeat dose of pentobarbital at 2 to 3 mg/kg is given.
If the patient is responding to noise, touch, or other stimuli without awakening, an additional dose of 0.1 mg/kg of Versed and/or 1 mg/kg of fentanyl citrate is given. Depending on the patient’s status and the clinical situation, if the patient has been given two full rounds of drugs and is not adequately sedated, then there should be careful considera- tion given as to whether to administer a third round of drugs or to abandon the procedure and call a failed sedation. The maximum total doses that we use in most diagnostic settings are 7 mg/kg (or 300 mg) for pentobarbital, 3 mg/kg (or 150 mg) for fentanyl, and 0.3 mg/kg (or 5 mg) for Versed.
It should be remembered that the respiratory depressant effects of all three of the drugs used in this regimen are potentiated by one another and are additive. This requires rigorous monitoring of the patient and immediate treatment of any evidence of respiratory depression as soon as it is recognized. It is also important to remember that to maximize safety, fentanyl should always be diluted and injected slowly or added to the fluid in the drip chamber of the IV infusion set and dripped in slowly, over about 1 minute, to avoid severe respiratory depression, apnea, or the feared complication of “wooden chest syndrome.” This syndrome of chest wall rigidity is a phenomenon during which the patient’s chest wall muscles become spastic, making ventilation extremely difficult. Although the exact mechanism of these muscle con- tractions has yet to be identified, many authors have described success in reversing chest wall rigidity with either naloxone (Narcan) or muscle relaxants such as succinylcholine, with rapid resolution.
References
1. American Academy of Pediatrics. Committee on drugs: guidelines for monitoring and management of pediatric patients during and after sedation for diagnostic and therapeutic procedures. Pediatrics 1992;89:
1110–1115.
2. American Society of Anesthesiologists Task Force on Sedation and Anal- gesia by Non-anesthesiologists. Practice guidelines for sedation and anal- gesia by non-anesthesiologists. Anesthesiology 2002;96:1004–1017.
3. Towbin RB, Cardella JF, Barr JD, et al. ACR Practice Guideline for Pediatric Sedation/Analgesia. ACR Guidelines and Standards Committee of the Interventional and Cardiovascular Radiology Commission, Practice Guide- lines and Technical Standards, Reston, VA. 2005:427–433.
4. Policy and Procedure for Intravenous Conscious Sedation. JCAHO Manual 1996:84–135.
5. Hoffman GM, Nowakowski R, Troshynski TJ, et al. Risk reduction in pediatric procedural sedation by application of an American Academy of Pediatrics/American Society of Anesthesiologists process model. Pedi- atrics 2002;109:236–243.
6. Holzman RS, Cullen DJ, Eichhorn JH, Philip JH: Guidelines for sedation by nonanesthesiologists during diagnostic and therapeutic procedures.
The Risk Management Committee of the Department of Anaesthesia of Harvard Medical School. J Clin Anesthesiol 1994;6:265–276.
7. Guidelines for the elective use of pharmacologic conscious sedation and deep sedation in pediatric dental patients. Pediatr Dent 1993;15:297–301.
8. American Academy of Pediatrics. Committee on drugs: guidelines for monitoring and management of pediatric patients during and after sedation for diagnostic and therapeutic procedures: addendum. Pediatrics 2002;110:836–838.
9. Coté CJ: Sedation protocols—why so many variations? Pediatrics 1994;
94:281–283.
10. Fowkes FG, Lunn JN, Farrow SC, et al. Epidemiology in anaesthesia. III:
mortality risk in patients with coexisting physical disease. Br J Anaesth 198;54:819–825.
