Pain is the most common reason a patient presents for health care. It is often undertreated for children in ED settings despite recognition of its importance.¹

Untreated pain in children causes short- and long-term consequences. For example, pain in infants can have lasting negative effects on neuronal development, pain threshold and sensitivity, coping strategies, emotionality, and pain perceptions.² Children receive less pain medication than adults for the same emergent complaints. The reasons for this “oligoanalgesia” include persistence of myths that children do not experience or remember pain, fear of using opioids in young patients, and difficulty assessing pediatric pain.³ The effects of untreated pain impact medical outcomes and are remembered even by preverbal children.² These effects may amplify with age: adolescents may avoid medical treatment, adults may refuse to donate blood, and geriatric patients may refuse flu shots because of the fear of needle pain. Children with a history of negative medical experiences show higher levels of anxiety prior to a venipuncture procedure and are less cooperative during the procedure. Further, high pain during medical visits predicts missed future medical appointments and poor health care follow-up.⁴ Older children also suffer sequela: untreated pain from lumbar puncture (LP) increases pain response with subsequent procedures.⁵ Immediate and long-term patient health are affected by inappropriate analgesia.

In the ED, the periodic evaluation of pain using self-reported pain scales has become routine for both staff and patients. The Wong-Baker Faces Pain Scale is widely used in the United States, but suffers from two methodological flaws: the smiling anchor to the left is rarely appropriate for anyone in the ED, and cultural and concrete thinking biases may limit endorsement of the tearful face (Fig. 14-1).⁶ The Faces Pain Scale – Revised is used more widely throughout the world, especially in the empirical literature (Fig. 14-2).^7,8 Other validated options include a vertical, graduated, and colored analog scale to assess pain.⁹ This upside-down triangle has the topmost part wide and red, representing the worst pain and the bottom part narrow and white, representing no pain. The scale has been found to be easier to administer than a standard visual analogue scale (VAS) and avoids the most common problem seen with “face”-based scales, choosing higher numbers because of unhappiness rather than pain. The verbal numerical rating scale, which involves asking a child to verbally report their pain intensity on a scale from zero to ten, is the most convenient pain scale to administer and requires no materials. However, it is recommended for use only in children developmentally capable of abstraction, typically 8 years and older.¹⁰

The value of pain assessment has empiric support: routine use of pain assessments improves treatment.¹¹ Incorporating pain assessment increases appropriate pain management in ED settings. Self-reporting pain scales are preferred; however, children under the age of 4 are generally not able to differentiate levels of pain.¹¹ Preschool children may lack the verbal and cognitive skills to report their pain or discomfort, thus several behavioral scales have been developed. The Children’s Hospital of Eastern Ontario Pain Scale (CHEOPS) and Faces, Legs, Activity, Cry, Consolability (FLACC) are two commonly used scales.^12,13 The FLACC has been validated in critically ill and cognitively impaired children.

VENIPUNCTURE

The American Academy of Pediatrics recommends pain control for venipuncture “whenever possible,” and numerous modalities are effective even within the time constraints of the ED.¹⁴ Topical anesthetics (e.g., prilocaine, lidocaine, tetracaine) stop sodium transmission, raising the action potential threshold so the fast pain impulse cannot be conducted. All local anesthetics contain hydrophilic and hydrophobic ends, the former being repelled by the oil layer of intact skin. Three common anesthetic formulations that overcome the skin barrier are eutectic mixture of local anesthetics (EMLA) (Astra-Zeneca, Wilmington, DE), LMX-4 (Eloquest Healthcare, Ferndale, MI), and tetracaine (e.g., Ametop Gel, Smith & Nephew Healthcare, Hull, UK; Synera, Galen US, Inc; Endo Pharmaceuticals, Malvern, PA).^15–20

EMLA is the first and most studied topical cream: prilocaine 2.5% and lidocaine 2.5%. Evidence supports reduction of pain with IV catheter insertion when applied for a minimum of 45 minutes.^16,17 EMLA can be left on up to 4 hours with a depth of penetration up to 6 mm. Numbness lasts an hour after removal. EMLA causes initial vasoconstriction, decreasing venipuncture success when left in place less than an hour, but does not affect success when left for an hour or more.^18,19 Venipuncture success improves the longer EMLA is in place, up to 92% when left on for 2 to 3 hours.¹⁹ Methemoglobinemia is a rare side effect more likely in preterm infants lacking the enzyme necessary for its reduction, and has not been reported in any randomized trials.²⁰ Current recommendations limit EMLA to infants of at least 37 weeks gestational age. A purpuric rash which resolves in 2 weeks without sequela has been described in multiple case reports.²¹

LMX-4 (previously called ELA-Max) places a 4% lidocaine preparation into liposomes for rapid absorption. Effective in 30 minutes, it works as well as EMLA for venipuncture pain.¹⁷ Rapid dissipation of the drug results in diminishing anesthesia approximately 40 to 60 minutes after application. LMX-4 improves cannulation success on the first attempt (74% vs. 55%) when compared with placebo, and lowers time of insertion and pain scores.²² LMX-4 does not require a prescription and does not carry the risk of methemoglobinemia. Several products enhance absorption of LMX-4 to make it more rapidly effective, including ultrasound devices and lasers.

Tetracaine gel, as also known as amethocaine (Ametop Gel, Smith & Nephew Healthcare, Hull, UK), is available alone and compounded with lidocaine. The 4% formulation works in 30 to 45 minutes, and lasts 4 to 6 hours with an efficacy similar to EMLA.²³

For venipuncture, tetracaine and lidocaine mixture (7%/7%) is available in a self-contained patch. Synera^® (ZARS Pharma, Salt Lake City, UT) in the United States and Rapydan^TM (Souderton, PA) in the European Union are designed to look like a child’s bandage and recommended for children aged 3 years and older. The patch contains a heating element that decreases absorption time and causes local vasodilation. This mixture was tested to show good topical anesthesia and pain control when applied for less time than EMLA or placebo.^24,25

LIDOCAINE DEVICES AND TECHNIQUES

Iontophoresis uses a low-voltage electrical current to drive the positively charged end of lidocaine through the epidermis. As the current flows to the negative reservoir, lidocaine is carried from the positive side into the skin. The current flow is noxious to some children. Time of application is at a minimum of 10 minutes. In contrast, a simple injection of buffered lidocaine using a small gauge needle prior to venipuncture is rapid and well tolerated.²⁶ Use of this method is inexpensive, depending on bundled hospital charges for the extra supplies.

The J-Tip^® (National Medical Products, Irvine, CA) puts lidocaine under the skin via a jet of compressed carbon dioxide. Studies have found the J-tip less painful for IV cannulation than EMLA cream or vapocoolant spray.^27,28 In addition, this method was found to be most cost-effective compared with other topical agents for IV cannulation.²⁹

COLD SPRAY AND VIBRATION DEVICES

Buzzy^® (MMJ Labs, Atlanta, GA), combining cold spray and vibration and placed proximal to the site of cannulation, decreased pain by half compared with cold spray, and increased IV success.³⁰ The Buzzy is as effective as 4% topical lidocaine cream for reducing pain and distress associated with IV cannulation, and allows the procedure to be completed more than 30 minutes faster than when lidocaine cream is used.³¹ Applying vapocoolant spray (Pain Ease^®, ethyl chloride, Gebauer, Cleveland, OH) to the penetration site has been used in hospitals for needle sticks, but the cold spray may cause veins to shrink, making cannulation difficult. Placebo-controlled randomized trials have produced varying results for venipuncture success.³² A recent review recommended against cold spray for pediatric patients.³³ Table 14-1 provides an algorithm for balancing optimal pain control with time available.

Open lacerations permit easy drug absorption, rendering the hydrophilic ester issue irrelevant. The first combinations of tetracaine and cocaine mixed with adrenaline (TAC) for vasoconstriction were very effective but created logistic difficulties with controlled substances. When lidocaine, epinephrine, and tetracaine (LET or LAT) demonstrated equal efficacy, LET became the standard of care for pediatric wound repair.³

A shred of LET-soaked cotton or LET mixed with methyl-cellulose just sufficient to fit in the wound is placed directly in the wound before irrigation and repair. The solution or gel can be held in place with an occlusive dressing, tape, or bandage. Numbness is present when the tissues blanch, usually after 20 minutes, and anesthesia lasts approximately 21 minutes after removal.³⁴ LET alone gives sufficient pain control for 70% to 90% of pediatric facial lacerations, and can decrease length of stay by 30 minutes compared with traditional lidocaine injection.³⁵

In extremities, LET has decreased efficacy (approximately 50%) but has not been shown to cause digital ischemia. Mucous membrane absorption is a theoretic concern, but the primary reason to avoid LET for oral lacerations is loss of vermilion border landmarks because of the blanching effect. EMLA has been used for laceration repair but has decreased numbing effect.³⁶

INFILTRATION

Both the tissue disruption from the volume of infiltrate and the acidic pH of lidocaine can cause increased pain when lidocaine with or without epinephrine is used for local anesthesia. In adults, pain is diminished when lidocaine is injected slowly with the smallest gauge needle possible.³⁷ Inject from within the wound, not through the adjacent intact skin. When possible, tap, jiggle, or vibrate several centimeters proximal to the site of infiltration to activate gate-controlling Aβ nerves and decrease the pain of injection. The chemical irritation from lidocaine itself can be minimized by buffering with sodium bicarbonate in a 9:1 ratio in the same syringe. Premixed syringes typically keep for a week in an unrefrigerated environment. Warm the syringe to body temperature to make the injection more comfortable than injection of refrigerated anesthetic.

Consider regional nerve blockade rather than direct local infiltration where appropriate. For a simple digital laceration, local injection has not demonstrated superiority to a digital block.³⁸ For foot lacerations, facial lacerations, and palmar lacerations, consider regional nerve blockade, but with smaller lacerations local infiltration may be less painful.

Incision and drainage is increasingly being performed under procedural sedation due to the difficulty adequately mitigating pain.³⁹ Using a combination of topical anesthetic over intact skin and local infiltration of lidocaine in a circular area prior to incision, pain may theoretically be reduced to an extent where intranasal or parenteral pain medicine alone or with nitrous oxide would be sufficient. Early trials suggest intranasal fentanyl may be preferable to parenteral morphine.⁴⁰ When packing abscesses with gauze, apply LET to the gauze for 20 minutes prior to removal to moisten the retained edges of packing for less painful removal. Placement of LMX-4 also may lead to spontaneous drainage and decrease the necessity for procedural sedation.⁴¹

Self-reported pharmacologic interventions to reduce pain associated with infant LP are used regularly by less than one-third of pediatric emergency medicine (PEM) faculty and fellows.⁴² Studies have demonstrated improved success rates when topical anesthetics are applied, further supporting a practical as well as palliative role.⁴³ When placed prior to collection of blood and urine, the rapid efficacy of LMX-4 makes it a feasible option for a septic workup, whereas EMLA requires an hour to achieve efficacy. When the LP needs to be performed emergently, apply as little as 0.1 mL of oral sucrose on a pacifier (e.g., Sweet-Ease, a 24% sucrose and water solution) for pain relief during the procedure. Effectiveness of sucrose is most commonly cited for preterm infants and neonates younger than 2 months of age, although it may provide pain relief in 6-month-old infants for less invasive procedures.⁴⁴

Lidocaine administered by J-Tip has also been shown to be effective option.⁴⁵ For older children, local anesthetics with or without an anxiolytic may be adequate. When a child is expected to require multiple LPs over the course of illness, as with leukemia, providing deep sedation initially improves subsequent fear and posttraumatic stress surrounding the procedure. Families of patients with leukemia prefer fentanyl/propofol sedation to propofol without analgesia.⁴⁶ Otherwise, provide optimal pain control to help avoid “hyperalgesia” and increase pain response with subsequent LPs.^46,47

EMLA has been demonstrated to decrease the pain of LPs in older children. By approximately 3 months of age, topical anesthetics will not penetrate sufficiently past the epidermis for optimal pain control. Infiltrate a generous amount of buffered lidocaine (approximately 1 mL per 10 kg of body weight up to a maximum of 5 mL) into the predural space for improved pain relief. Short-acting opioids (e.g., fentanyl) can further improve comfort with the procedure.