For displaced fractures or for children reporting higher pain scores, IV, IM, or IN pain medications may be necessary. Fentanyl may be preferable as the initial narcotic as it is a fast-acting drug with a shorter duration of action compared to morphine, which is slower in onset but has a longer duration.104 IN fentanyl provides safe and effective analgesia to children with pain when an IV is not available.105 In addition, subdissociative doses of ketamine at 0.25 to 0.5 mg/kg IV can be administered for analgesia.104
AUTHOR’S PREFERRED METHOD OF TREATMENT
In our ED, pain management guidelines begin in triage with immobilization and application of ice packs to the injured extremity. The Wong–Baker Faces Pain Rating Scale is used for children 3 years and older. For a moderate pain score of 4 or higher, both ibuprofen (10 mg/kg) and acetaminophen (15 mg/kg) are given orally. For higher pain scores, IN fentanyl is offered for rapid pain relief and can be given prior to x-ray evaluation. Given the short duration of IN fentanyl, additional pain medications (e.g., ibuprofen, acetaminophen, oxycodone, or IV fentanyl) should be considered, depending on the child’s pain level and type of fracture.
Pain Management After Discharge
After ED discharge, children report the highest levels of pain in the first 48 hours after injury and use pain medications for analgesia for up to 3 days after injury.38 Children with both nondisplaced and displaced fractures requiring ED reduction report clinically meaningful pain after discharge.111 Caregiver’s instructions for pain management after ED discharge should include the use of oral analgesics (e.g., ibuprofen for moderate pain and oxycodone for higher levels of pain) (Table 3-11).5,23,37,38 Given the risks associated with codeine,78 our institution has removed this medication from the formulary with a recommendation to use oxycodone instead.
PROCEDURAL SEDATION FOR EMERGENCY DEPARTMENT FRACTURE REDUCTION
Procedural sedation is defined as the method of administering sedatives or dissociative medications, with or without analgesics, to induce an altered state of consciousness, which allows the patient to tolerate unpleasant procedures while maintaining cardiorespiratory function.8 Fracture reduction and casting for the majority of displaced and angulated fractures can be safely and successfully achieved in the ED with procedural sedation for analgesia, anxiolysis, amnesia, and sedation.87 Sedation occurs along a continuum as the drug dose increases and drug levels in the central nervous system (CNS) increase, consciousness decreases, and the risk of cardiorespiratory depression increases. Minimal sedation, or anxiolysis, is a drug-induced state where the patient can still respond normally to verbal commands, but may have cognitive or coordination impairment while maintaining normal cardiorespiratory function. With moderate sedation (previously conscious sedation) patients may respond purposefully to verbal commands, either alone or with tactile stimulation, while maintaining cardiorespiratory function. The next level of sedation is dissociative sedation, which results in profound analgesia and amnesia while the patient is able to retain protective airway reflexes and maintain cardiopulmonary function. With deep sedation patients are not easily aroused, but may respond purposefully with repeated or painful stimulation. This level of sedation may result in impairment of spontaneous ventilation while cardiovascular function is maintained. Finally, with general anesthesia the patient has loss of consciousness with impairment of ventilatory and sometimes cardiovascular function.69,87
Providers administering procedural sedation must be trained to rapidly identify and treat the most common cardiorespiratory complications of sedation agents (respiratory depression, central and obstructive apnea). They must also be able to perform maneuvers to maintain airway patency and provide assisted ventilation, if necessary. At least two providers are required: one to administer medications and provide airway support and another for monitoring and documentation.70,87
To evaluate children for the potential risks of sedation, a presedation assessment should be performed. This assessment should include a directed history (including allergies and history of any prior adverse reactions to sedatives or anesthetics) and a physical examination, with emphasis on the child’s airway and cardiopulmonary status.87 The American Society of Anesthesiologists’ (ASA) physical status classification for preoperative risk stratification can be used to stratify risk, with most children undergoing ED procedural sedation being ASA class 1 or 2 (Table 3-1).69
TABLE 3-1 ASA Physical Status Classification System
Concern for pulmonary aspiration of gastric contents is the primary reason for assessment of preprocedure fasting status. Overall, the relative risk of aspiration during ED procedural sedation is rare and is likely much lower than during general anesthesia.92 A prospective study of 905 children undergoing ED procedural sedation found that 56% were not fasted in accordance with established guidelines, and there was no association between preprocedural fasting and adverse events.3 For children in the ED, a prolonged fasting period would not allow for a timely fracture reduction to be performed. However, this must be balanced with consideration of a patient’s individual risk of aspiration, including recent oral intake, for ensuring safe and effective, as well as timely, procedural sedation.
A consensus-based clinical practice advisory for ED preprocedural fasting outlined the stratification of aspiration risk by assessment of: (1) Potential airway/respiratory complications and systemic disease; (2) timing and nature of recent oral intake; (3) urgency of the procedure; and (4) targeted depth and length of sedation.53 For a standard risk patient (normal airway, ASA < 3) with no oral intake or only clear liquids in the 3 hours prior to the procedure, all levels of sedation could be performed for fracture reduction. For a standard risk patient with a light snack 3 hours prior to the procedure, dissociative sedation with ketamine, >20 minutes of moderate sedation or <10 minutes deep sedation would be acceptable. If the standard risk patient had a heavier snack or meal in the 3 hours prior to sedation, dissociative sedation or >20-minute moderate sedation would be acceptable.53
Continuous close observation and monitoring of the child is crucial throughout the sedation. The child’s face, mouth, and chest wall must be observed for respiratory effort. Noninvasive monitoring with continuous pulse oximetry, capnography, and cardiorespiratory monitoring must be maintained during the procedure. Capnography noninvasively measures the concentration of carbon dioxide in exhaled breath, providing continuous monitoring of ventilatory status, including respiratory rate, and provides the earliest indication of respiratory compromise.52 In young children who can rapidly develop oxygen desaturation because of their smaller functional residual capacity and higher oxygen consumption,90 early detection of respiratory compromise is critical in preventing more serious complications related to prolonged hypoxia.69 Vital signs should be recorded before, during, and after the sedation at predetermined intervals, depending on the level of sedation.
Supplemental oxygen (e.g., high-flow oxygen by mask) administered during procedural sedation is recommended to reduce the risk of sedation-associated hypoxia.7,9,33 Suction, reversal agents, and medications and equipment for advanced airway management must be readily available.87 The highest risk for complications occurs 5 to 10 minutes after IV drug administration and immediately following the completion of the procedure, when the painful stimuli have concluded.70 After the procedure is completed, the child should be monitored until he/she has returned to baseline with normal vital signs (Tables 3-2, 3-3, and 3-4) and age-appropriate level of consciousness, and can talk and sit as appropriate for their age (Table 3-5).69
TABLE 3-2 Normal Values for Heart Rate by Age
TABLE 3-3 Normal Values for Blood Pressure by Age
TABLE 3-4 Calculation of Normal Blood Pressure by Age
TABLE 3-5 Recommended Discharge Criteria After Sedation
PHARMACOLOGIC AGENTS USED IN PEDIATRIC PROCEDURAL SEDATION AND ANALGESIA
Nitrous Oxide (N8O)
Nitrous oxide (N2O) is an odorless gas that provides anxiolysis and mild analgesia while the patient remains awake and is able to follow commands. It can be used for mild to moderately painful procedures as a sole agent or can be used for more painful procedures supplemented with local or regional anesthesia (e.g., hematoma or nerve blocks). Nitrous oxide is dispensed at concentrations between 30% and 70% in combination with oxygen.104 Because of its rapid diffusion into air-filled cavities, N2O is contraindicated in a patient with pneumothorax, bowel obstruction, head injury, or pregnancy. Other contraindications for the use of nitrous oxide include cardiac or pulmonary disease. Emesis is the most common adverse effect, reported in up to 10% of patients (Table 3-6).104
TABLE 3-6 Medications for Analgesia and Procedural Sedationa
There is a rapid onset of action (5 minutes to peak effect) and offset (5 minutes) because of its low blood–gas solubility coefficient allowing it to rapidly reach equilibrium in the brain.104 As a result, fracture reduction can proceed after 5 minutes of N2O administration. Nitrous oxide and a hematoma block provide anxiolysis, amnesia, and analgesia for fracture reduction, while allowing the older child to be awake and responsive.56 After the fracture reduction, supplemental oxygen at 100% is administered by face mask for 5 minutes to wash out the nitrous oxide and palliate any diffusional hypoxia.56,104 A randomized ED comparison of N2O with a hematoma block to ketamine plus midazolam in 102 children with fracture reduction, after initial oxycodone administration, found similar increases in distress during the reduction in both groups. However, the N2O/hematoma block group had a significantly shorter recovery time and reported fewer adverse effects.76 Randomized controlled trials of N2O compared to other sedation regimens for ED fracture reduction are limited;85 therefore, the specific use of N2O, with or without a hematoma block, should be based on the skill and training of the treating providers as well as the individual patient and fracture type.
AUTHOR’S PREFERRED METHOD OF TREATMENT
When nitrous oxide is used by the authors it is most commonly used with a hematoma block. The authors use this regimen in patients with mild to moderately displaced fractures requiring reduction provided the patient can cooperate with self-administration of N2O by face mask.
Benzodiazepines and Opioids
When used in combination, benzodiazepines and opioids are another option for fracture reduction, with midazolam and fentanyl being used the most commonly for moderate and deep sedation. When used together these two drugs have a synergistic effect with a higher risk of hypoxia and apnea compared to they are when used alone. Therefore, careful IV titration with close monitoring for respiratory depression must be exercised when using these agents.69,77,104
Midazolam is a short-acting benzodiazepine with anxiolytic, amnestic, sedative, hypnotic, muscle relaxant, and anticonvulsant properties; however, it does not provide analgesia.69,104 With IV administration, peak effect occurs within 2 to 3 minutes and lasts 45 to 60 minutes. In addition, midazolam can be administered intranasally or buccally in an aerosolized form, without need for IV access.67,104 Midazolam can also be administered orally, but may result in unreliable clinical effects due to first-pass hepatic metabolism.104
Adverse effects of midazolam include mild cardiovascular depression, nausea, vomiting, and paradoxical reactions – which may be manifest by inconsolable crying, combativeness, disorientation, agitation, and restlessness.63,69 Flumazenil is the benzodiazepine antagonist used to reverse severe respiratory depression and oversedation.63 The duration of action of flumazenil is shorter (20 to 30 minutes) than that of midazolam, so multiple doses may be required to maintain reversal of benzodiazepine effects.104
IV fentanyl is a rapidly-acting, extremely potent opioid with peak effect at 2 to 3 minutes and a duration of 20 to 60 minutes. It is preferred to morphine for procedural sedation because of its faster onset, shorter recovery time, and lack of histamine release. In infants and young children, more frequent dosing may be required as they have a higher clearance of the drug.104 As it provides no sedation or anxiolysis at low doses (1 to 2 mcg/kg), fentanyl should be used in combination with a benzodiazepine (e.g., midazolam) for sedation of painful procedures.69 Adverse effects of fentanyl include nasal pruritus and respiratory depression. Naloxone is an opioid antagonist that reverses opioid effects within 1 to 2 minutes of administration and lasts 20 to 40 minutes.104
Ketamine is a rapidly acting dissociative agent, which provides sedation, analgesia, and amnesia, while preserving cardiovascular stability and airway reflexes. This drug is classified as a dissociative as it chemically disconnects the thalamocortical and limbic systems resulting in a dissociation of the CNS to external stimuli, causing a trancelike cataleptic state.48,63 It has a rapid onset of action (IV: 30 to 60 seconds; intramuscular [IM]: 3 to 5 minutes), with sedative effects lasting 10 to 15 minutes with a single dose and 20 to 30 minutes with multiple doses. Given its rapid onset, ketamine should not be administered until the orthopedist is ready to begin the procedure. The initial dose of IV ketamine should be administered over 30 seconds, as rapid administration can result in transient central apnea.48 Recovery time is generally 50 to 110 minutes for IV administration and 60 to 140 minutes for IM.64,80,100,104 Although it may be given IM, the IV route is generally preferred, as recovery is faster and emesis less common. It is associated with nystagmus, diplopia, pupillary dilatation, increased muscle tone, and transient hypertension.104 Ketamine is contraindicated in children <3 months old because of the increased risk for airway adverse events, and in patients with a history of psychosis. Relative contraindications include: History of airway problems (e.g., tracheal surgery), active pulmonary infection or asthma, cardiovascular disease, any concern for increased intracranial pressure, or a thyroid disorder.48
Ketamine does not exhibit a typical dose–response relationship like other sedative and analgesic agents. At lower doses (0.25 to 0.5 mg/kg IV) it causes analgesia and disorientation, but does not result in a dissociative effect. These subdissociative doses can be used for analgesia prior to a procedure or in combination with propofol for painful procedures.104 To reach a dissociative state, a dosing threshold for ketamine of approximately 1 to 2 mg/kg IV or 4 to 5 mg/kg IM needs to be administered. Additional or higher doses do not deepen the dissociative state and do not affect airway integrity; therefore, additional doses are only needed to maintain the dissociative state over time.48,69
Adverse events associated with ketamine are primarily respiratory compromise, emesis, or recovery reactions. A meta-analysis of airway and respiratory events associated with ketamine analyzed 8,282 pediatric ketamine sedations and found that the overall prevalence of airway or respiratory adverse events was 3.9%, including 0.3% with laryngospasm and 0.8% with apnea.50 A secondary case-control analysis from this larger meta-analysis did not demonstrate any clinical, dosing, or age-related factors associated with an increased risk of laryngospasm.49 Although laryngospasm may be a rare event, the clinician administering ketamine must be prepared to rapidly identify and manage respiratory complications including performing bag-valve-mask ventilation or tracheal intubation.48 Another meta-analysis of the same cohort of 8,282 children found the overall prevalence of emesis was 8.4%, any recovery agitation (e.g., agitation, crying hallucinations, and nightmares) 7.6%, and recovery agitation described as severe and/or requiring treatment 1.4%. Early adolescence and IM administration was associated with more ketamine-associated emesis. There was no age relationship or change in risk with coadministered medications and recovery agitation.51 A clinical practice guideline for ED ketamine sedation supports its use in healthy adults without cardiac disease and recommends treatment of recovery reactions with benzodiazepines.48 In a study of post-ED discharge outcomes after procedural sedation, 18% of children had emesis, but there was a low prevalence of adverse behavioral events.82
The coadministration of prophylactic anticholinergics to decrease hypersalivation and the risk of airway complications is no longer recommended. Similarly, the prophylactic use of benzodiazepines to prevent recovery reactions is also no longer recommended, although they should be available to treat any unpleasant recovery reactions that may occur. In contrast, ondansetron may either be given prophylactically for vomiting (number needed to treat 13),72 or may be given as needed after nausea/emesis has occurred.48,104 When considering narcotic pretreatment for pain, one retrospective study of 858 children given ketamine for procedural sedation examined the use of morphine pretreatment and found no increase in the number of adverse events compared to those children without morphine pretreatment.118 Pretreatment with morphine before ketamine sedation, however, is associated with a longer recovery time compared to having no narcotic pretreatment.75
At dissociative doses ketamine is a very effective agent for ED fracture reduction because of its dissociative effects while preserving airway and cardiopulmonary status.77 One study of 260 children randomized them to either a combination of fentanyl and midazolam or ketamine and midazolam for ED fracture reduction. The children receiving ketamine and midazolam had lower distress scores and parental ratings of pain and anxiety than children in the fentanyl group, and had fewer respiratory complications. Vomiting was more frequent in those receiving ketamine, and they also had a longer recovery.64 Another study of 114 children given ketamine either IV or IM for fracture reduction reported that children had minimal or no pain during the reduction, as measured by the orthopedic surgeons using the Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS) with high parent satisfaction.80 When adverse effects between ketamine and fentanyl/midazolam are compared, ketamine is associated with fewer respiratory adverse events, but more vomiting.91,99
Propofol is an extremely rapidly acting (15 to 30 seconds) sedative with a narrow therapeutic range, and as a result has a higher risk of airway obstruction and central apnea.63,104 It also has a very short recovery time (5 to 15 minutes) and inherent antiemetic properties.69 With no analgesic properties, it must be combined with either ketamine (ketofol) or a narcotic for painful procedures. Several studies have reported the safety and efficacy of propofol for painful ED procedures including fracture reduction.12,47,107 More recently studies have examined the use of ketamine/propofol (ketofol) for fracture reduction and reported effective sedation and analgesia. The most commonly reported adverse effects were respiratory complications, inadequate sedation, or recovery agitation.10,121 Given the risks of apnea and respiratory depression associated with both of these drugs, providers must be skilled in the administration of the drugs and management of potential adverse reactions when ketamine and/or propofol are used for fracture reduction.
AUTHOR’S PREFERRED METHOD OF TREATMENT
For angulated and displaced fractures requiring manipulation for reduction and casting, the authors prefer the use of IV ketamine, without premedication, as it provides the most effective sedation and analgesia with the least risk of respiratory adverse events.85 Ketamine sedation must be administered by a clinician who is knowledgeable about the effects and risk of this medication. The provider must also be skilled in the rapid recognition of respiratory complications as well as the capability of advanced airway management including bag-valve-mask ventilation and tracheal intubation, which may be indicated for laryngospasm. Although fentanyl and midazolam may be used for fracture reduction, when compared to the use of ketamine and midazolam for fracture reduction, fentanyl plus midazolam is more likely to be associated with respiratory complications and less effective sedation.64,85 The use of propofol for procedural sedation is expanding in our ED, but at this time is not routinely being used for fracture reduction.
PERIOPERATIVE PAIN MANAGEMENT
Regional Anesthesia in Children for a Musculoskeletal Injury
The purpose of regional anesthesia is to provide site-specific analgesia, and it can be divided into three categories: Neuraxial, peripheral, and field blocks. Regional anesthetics are often preferred when possible over general anesthetics because of their decreased systemic side effects. Neuraxial blockade is injection of anesthetic agents into the epidural or intrathecal space. As this procedure is typically performed by an anesthesiologist, this chapter will focus on the latter two forms of blockade. As always, any of the described techniques should be performed within the strict comfort level of the treating physician and are not recommended for use without a clear understanding of the relevant anatomy. We will focus on specific techniques to perform procedural regional anesthesia with a “how to” organization. A basic review of local anesthetics will also be included.
Regional and Local Anesthetic Agents
Several effective techniques for local and regional anesthesia have been described in the pediatric population including hematoma, IV regional, and regional nerve blocks. As always, use of these medications requires a thorough understanding of the pharmacokinetics and appropriate dosing of these drugs as well as proficiency in the techniques of administering them safely. Local and regional anesthetic drugs work by blocking the conduction of nerve impulses. At the cellular level they depress sodium ion flux across the nerve cell membrane. This results in the inhibition of the initiation and propagation of action potentials.108,122 After injection, local anesthetics diffuse toward their intended site of action and also toward nearby vasculature where uptake is determined by the number of capillaries, the local blood flow, and the affinity of the drug for the tissues. Vasoconstrictors such as epinephrine are mixed with local anesthetics to decrease the vascular uptake and prolong the anesthetic effect.
Duration of action for the various local anesthetic medications is also determined in part by the type of regional block performed. For example, single-dose brachial plexus blocks tend to have a far longer duration than single-dose epidural or subarachnoid blocks.30 Adverse effects in the tissue surrounding injection sites have been described and include erythema, swelling, and rarely, ischemia when injected into tissues supplied by terminal arteries. Adverse systemic effects are caused by high blood levels of local anesthetics and include tinnitus, drowsiness, visual disturbances, muscle twitching, seizures, respiratory depression, and cardiac arrest. Bupivacaine can be particularly dangerous because it binds with high affinity to myocardial contractile proteins and can cause cardiac arrest.
Before placing any anesthetic block it is important to consider ahead of time the equipment and medication that will be required for the procedure. Simple blocks may only require a weight-based dose of the preferred anesthetic agent, needle(s), syringe(s), and a sterile cleaning solution. For blocks that are placed in deeper planes such as the axillary and femoral nerve blocks and IV (Bier) blocks, additional equipment considerations include appropriate electrocardiographic monitoring, airway management equipment, and a double-cuffed tourniquet (Bier block). In addition, medications that should be readily available include IV diazepam to manage seizures and IV lipid to prevent potential cardiovascular collapse induced by accidental intravascular injection of the anesthetic (especially with bupivacaine). Again, a thorough understanding of the appropriate dosing and resuscitation procedures in the event of local anesthetic toxicity is necessary before performing these procedures. The use of nerve stimulators with insulated needles has gained in popularity. Their use as well as the use of ultrasound have dramatically improved efficacy of many regional blocks.
Local Anesthesia Toxicity
At least three types of adverse reactions can occur from local anesthetic agents. Clinically, the most important is systemic toxicity of the CNS and cardiovascular system from a relative overdose into the circulation (Table 3-7). This type of reaction is not a medication allergy, but is a function of having too much medication into the bloodstream. In the presence of a major artery, even a low dose of a local anesthetic can lead to seizure activity. In most cases, however, the severity of systemic toxicity is directly related to the concentration of local anesthetic in the bloodstream.30 Seizures and cardiac arrest may be the initial manifestations of systemic toxicity in patients who rapidly attain a high serum level of medication.39,86,94 Agents with greater intrinsic potency, such as bupivacaine and etidocaine, require lower levels for the production of symptoms.30 Dysrhythmias and cardiovascular toxicity may be especially severe with bupivacaine, and resuscitation of these patients may be prolonged and difficult.4,30 The prevention and treatment of acute local anesthetic systemic toxicity are outlined in Table 3-8. Although the potential for CNS toxicity may be diminished with barbiturates or benzodiazepines, given either as premedications or during the treatment of convulsions, these measures do not alter the cardiotoxic threshold of local anesthetic agents. With rapid and appropriate treatment, the fatality rate from local anesthetic-related seizures can be greatly decreased.30 It is essential to stay within accepted dose limits when using any local anesthetic (Table 3-9). To aid in dose calculations, a simple formula for converting percent concentration to milligrams per milliliter is provided in Table 3-10. Local nerve damage and reversible skeletal muscle changes have also been reported from the use of local anesthetics.30
TABLE 3-7 Manifestations of Local Anesthetic Toxicitya
TABLE 3-8 Prevention and Treatment of Acute Local Anesthetic Systemic Toxicity
TABLE 3-9 Maximal Recommended Doses of Commonly Used Local Anesthetics in Children
TABLE 3-10 Conversion Formula from Percent Concentration to Milligrams/Milliliter
Intravenous Regional Anesthesia
Bier block anesthesia was originally described in 1908 by August Bier who used IV cocaine to obtain analgesia.15,17,60 Although it declined in popularity as brachial plexus blocks were developed, it was revived in 1963, when its safe and successful use for the reduction of forearm fractures in adults was reported.58 Subsequently, a number of studies have described the effective use of this technique of anesthesia for the treatment of upper extremity fractures in children in an ambulatory setting.11,15,17,21,74 The block has also been described for use in lower extremity fractures, but is less commonly utilized for this indication.74
The technique for administering the Bier block in the upper extremity involves placement of a deflated pneumatic cuff above the elbow of the injured extremity. Holmes58 introduced the concept of two cuffs in an effort to minimize tourniquet discomfort with prolonged inflation, but the practice has not proven to be necessary for the limited amount of time it takes for fracture reduction in a child.11,17,29 The tourniquet should be secured with tape to prevent Velcro failure.88 IV access is established in a vein on the dorsum of the hand of the injured extremity with a 22- or 23-gauge butterfly needle. The arm is exsanguinated by elevating it for 1 to 2 minutes (Fig. 3-1A). Although exsanguination with a circumferential elastic bandage is described classically, this method can be more painful and difficult to perform in an injured extremity and is no more efficacious than the gravity method.17,29,54,60 The blood pressure cuff is then rapidly inflated to either 100 mm Hg above systolic blood pressure or between 200 and 250 mm Hg (Fig. 3-1B).17,29,54,60 The arm is lowered after cuff inflation. Next, lidocaine is administered, the IV catheter removed, and reduction of the fracture performed (Fig. 3-1C). In the traditional technique, the lidocaine dose is 3 to 5 mg/kg11,29,88 and, in the “mini-dose” technique, 1 to 1.5 mg/kg.17,54,60
The tourniquet is kept inflated until the fracture is immobilized and radiographs are obtained, in case repeat manipulation is necessary. In any event, the tourniquet should remain inflated for at least 20 minutes to permit the lidocaine to diffuse and become adequately fixed to the tissues, thus minimizing the risk of systemic toxicity.88,115 The blood pressure cuff may be deflated in either a single stage or graduated fashion, although single stage release has proven to be clinically safe and technically easier.42,60,88 During the entire procedure, basic respiratory monitoring is required, and cardiac monitoring is also suggested because of the potential cardiac toxicity. Routine IV access in the uninjured extremity is highly recommended because of the potential for cardiac effects, but is not required.11,54 Patients should be observed for at least 30 minutes following cuff deflation for any adverse systemic reactions. Motor and sensory function typically returns during this period, allowing assessment of neurovascular status of the injured extremity prior to discharge.115
The literature within the past decade certainly speaks to the effectiveness of the traditional Bier block, utilizing a lidocaine dose of 3 to 5 mg/kg, in managing forearm fractures in children. Four large series with a total of 895 patients undergoing this technique demonstrated satisfactory anesthesia and successful fracture reduction in over 90% of cases.11,29,88,113 The most common adverse effect of the procedure in these studies was tourniquet pain in about 6% of patients.29,113 One patient experienced transient dizziness and circumoral paresthesias.113 One patient developed persistent myoclonic twitching following tourniquet deflation and was hospitalized for observation.88
Despite the efficacy and relatively low number of complications with the “traditional” Bier block (lidocaine, 3 to 5 mg/kg), concerns and anecdotal reports of systemic lidocaine toxicity (i.e., seizures, hypotension, tachycardia, arrhythmias) have prompted the development of a “mini-dose” (lidocaine, 1 to 1.5 mg/kg) technique of Bier block anesthesia.17,42,60 Reports by Farrell et al.42 and Bolte et al.17 utilizing a lidocaine dose of 1.5 mg/kg and by Juliano et al.60 using a dose of 1 mg/kg in a total of 218 patients have shown the mini-dose Bier block to be effective in achieving adequate anesthesia in 94% of children studied. Although the exact mechanism of action is uncertain, the primary site of action of the Bier block is thought to be the small peripheral nerve branches. At this anatomic level, blockade is better achieved with a larger volume of anesthetic that can be distributed more completely to the peripheral nerve receptors. It appears to be the quantity (i.e., volume) and not the dose of anesthetic that predicates success of the block. For any given dose of lidocaine, diluting the concentration permits the administration of a larger volume of fluid (Table 3-4). This mechanism explains the success of the mini-dose technique. In the series by Juliano et al.60 forearm fracture reduction was pain free in 43 of 44 patients (98%) following Bier block performed with a very dilute lidocaine solution (0.125%) and a relatively small total dose (1 mg/kg).
Bier block anesthesia, using either the traditional or mini-dose technique has several advantages. First, the technique is fairly easy to administer. Also the onset of action of the block is relatively fast (<10 minutes), but also of relatively short duration, which allows for the assessment of neurovascular function in the extremity after fracture reduction and immobilization. However, rapid recovery may also be considered a disadvantage as the analgesic effect of the local anesthetic is lost once the tourniquet is deflated. A recent report in adults examined the addition of the nonsteroidal anti-inflammatory drug (NSAID) ketorolac to the local anesthetic solution and found that patients did obtain prolonged analgesia after the tourniquet was released.97 An empty stomach is not required. However, no pediatric studies have been performed on this technique.
Tourniquet discomfort is the most common adverse side effect. Inadvertent cuff deflation with loss of analgesia or systemic toxicity is a potentially significant problem. Compartment syndrome has also been reported. Technically, placing the tourniquet and obtaining IV access in the injured extremity can be a challenge in the uncooperative child, and application of the splint or cast can be cumbersome with the tourniquet in place. IV regional anesthesia is unsuitable for lesions above the elbow.58 This technique is contraindicated in patients with underlying heart block, known hypersensitivity to local anesthetic agents, and seizure disorders. Although not completely contraindicated, caution is urged when using this technique in patients with underlying hemoglobinopathies such as sickle cell disease.
AUTHOR’S PREFERRED TREATMENT
The basic steps involved in performing an Bier block are as follows:
1. Confirm the immediate availability of a functioning positive-pressure oxygen delivery system, as well as appropriate airway management equipment. Also, confirm the immediate availability of medications for the treatment of anesthetic-induced convulsions (Table 3-8). Personnel familiar with administration of rescue medications and emergency airway management should also be available.
2. Place an IV in the contralateral, uninjured, arm. A patent IV line is of paramount importance in treating the complications of this block. Obtain a baseline set of vital signs, including heart rate, respiratory rate, oxygen saturation, and blood pressure. Pulse oximetry as well as cardiorespiratory status should be monitored continuously.
3. Select an appropriate tourniquet. An orthopedic tourniquet that can be fastened securely should be used. Because Velcro may become less adhesive with time, check the tenacity of the tourniquet before use. As an added safety measure, the tourniquet may be covered with strong adhesive tape or an elastic bandage after application. The tourniquet should fully encircle the arm and overlap back on itself by at least 6 cm. The arm may be minimally padded with cast padding underneath the tourniquet.17 If a pneumatic tourniquet is used, the provider must be familiar with the location of the tourniquet pressure gauge and valves, because these features vary in location from model to model.29 Narrow-cuffed double tourniquets may not effectively occlude arterial flow, and their use has been discouraged.58 Tourniquet discomfort should not be a problem during short procedures, but if this develops, a second tourniquet can be applied distally over the anesthetized area of the arm.
4. Palpate the radial pulse of the injured limb.
5. Place and secure a short 22-gauge cannula or 23-gauge butterfly needle in a vein on the dorsum of the hand of the fractured limb. IV catheters can be secured more readily. If a distal vein is unavailable, a proximal vein or even an antecubital vein can be used, but may result in a less effective block.58
6. With the tourniquet deflated, exsanguinate the limb by vertically elevating it above the level of the heart for 60 seconds.
7. Rapidly inflate the tourniquet to a pressure of 225 to 250 mm Hg or 150 mm Hg above the patient’s systolic blood pressure.43 Check for disappearance of the radial pulse. Cross-clamping the tubing of the cuff after inflation is discouraged because it might prevent detection of a small leak.58 Constant observation of the cuff pressure gauge is recommended.
8. Lower the extremity and slowly inject the local anesthetic. This injection should be done over a period of 60 seconds. A concentration of 0.125% to 0.5% plain lidocaine (1.25 to 5 mg/mL) is used. Bupivacaine is contraindicated for this block because of its cardiotoxicity. To prevent thrombophlebitis, the local anesthetic solution must be free of any additives or preservatives.31 In different studies, the recommended dose of lidocaine has varied from 1.5 to 3 mg/kg.11,17,29,42,88,113 A dose of 1.5 mg/kg appears to be safe and effective and may be associated with a decreased rate of complications.17 One study has recommended a maximal lidocaine dose of 100 mg for this block.42 The skin of the extremity becomes mottled as the drug is injected. The patient, unless he or she is very sedated, and the parents, if they are watching, should be warned that the extremity will look and feel strange. Analgesia and muscle relaxation develop within 5 minutes of injection.58 For fractures at the wrist, placement of a regular Penrose drain tourniquet around the distal forearm may improve distribution of the local anesthetic solution at the fracture site.
9. To improve analgesia for fracture reduction, the last 2 mL of local anesthetic solution may be injected directly into the fracture hematoma. The technique of local infiltration anesthesia, or hematoma block, is discussed later in this chapter.
10. Reduce the fracture and apply the cast or splint.
11. Leave the cuff inflated for at least 15 minutes, even if the surgical procedure takes less time to prevent significant entry of local anesthetic into the general circulation.58
12. Monitor the patient closely for at least 15 minutes for any complications related to the block. The treatment of local anesthetic-induced systemic toxicity has been discussed (Table 3-8).
13. Depending on whatever sedation has been administered, the patient should be monitored until discharge criteria are met (Table 3-5). An assistant must be present to watch the patient, the tourniquet, and the monitors at all times.