Preventing and Treating Pain and Stress among Infants in the Newborn Intensive Care Unit
Carol Spruill Turnage
Michelle A. LaBrecque
I. BACKGROUND.
Recognition that both premature and full-term infants experience pain has led to increasing appreciation of the prevalent problem of undertreatment of stress and pain of infants who are hospitalized in the newborn intensive care unit (NICU). Both humanitarian considerations and scientific principles favor improved management strategies to prevent pain and stress whenever possible and, when discomfort is unavoidable, to provide prompt and appropriate treatment.
A. Fetal and neonatal physiologic responses to pain. Peripheral nerve receptors develop very early in gestation and are abundant by 22 weeks of gestation on most of the fetal body. Evidence of functional thalamocortical connections that are required for conscious perception of pain has been demonstrated as early as 29 weeks of gestation. Autonomic and endocrine responses to noxious stimuli are present even earlier in development. Although this stress response may not indicate fetal pain perception at a conscious level, it has harmful effects on the developing fetus, and the administration of analgesia has been shown to suppress these responses.
Early in development, overlapping nerve terminals create local hyperexcitable networks, enabling even low-threshold stimuli to produce an exaggerated pain response. Fetal wounds heal more quickly and with less scarring than those of infants, children, or adults. The process, in part, involves sprouting of sensory nerve endings in and near the site of tissue injury. Although it seems to enhance wound healing, hyperinnervation results in hypersensitivity to painful stimuli that persists after wound healing has occurred. Repeated noxious stimuli further alter sensitivity to painful stimuli and appear to lower the pain threshold, slow the recovery, and adversely affect long-term outcomes.
Physiologic responses to painful or stressful stimuli include increases in circulating catecholamines, increased heart rate and blood pressure, and elevated intracranial pressure. The fetus is capable of mounting a stress response beginning at approximately 23 weeks of gestation. The autonomic and other markers of the stress response of the immature fetus or preterm infant, however, are less competent than that of the more mature infant or child. Therefore, among immature infants, neither the common vital sign changes associated with pain or stress (e.g., tachycardia, hypertension) nor behavioral cues (e.g., agitation) are reliable indicators of painful stimuli. Even when the infant’s stress response is intact, persistence of painful stimuli for hours or days fatigues or deactivates the sympathetic nervous system response, obscuring the signs of pain or discomfort.
B. Medical and developmental outcomes
Neonatal medical and surgical outcomes. Neonatal responses to pain may worsen the compromised physiologic states such as hypoxia, hypercarbia, acidosis, hyperglycemia or respiratory distress. Early studies of surgical responses showed more stable intraoperative course and improved postoperative recovery among infants who received perioperative analgesia and anesthesia. Changes in intrathoracic pressure due to diaphragmatic splinting and vagal responses produced in response to pain following invasive procedures precipitate hypoxemic events and alterations in oxygen delivery and cerebral blood flow.
Neurodevelopmental outcomes. Behavioral and neurologic studies suggest that preterm infants who experience repeated painful procedures and noxious stimuli are less responsive to painful stimuli at 18 months corrected age. However, at 8 to 10 years of age, unlike their normal birth weight peers, infants who were born at or below 1,000 g birth weight rate medical pain intensity greater than measures of psychosocial pain. These data provide evidence that neonatal pain and stress influence neurodevelopment and affect later perceptions of painful stimuli and behavioral responses, and that prevention and control of pain are likely to benefit infants. There are few large randomized clinical trials of pain management. The Neurologic Outcomes and Preemptive Analgesia in Neonates (NEOPAIN) trial evaluated preemptive analgesia with morphine infusion up to 14 days among ventilated preterm infants and showed no overall difference in the primary composite outcome (neonatal death, severe intraventricular hemorrhage [IVH], or periventricular leukomalacia [PVL]) between placebo and preemptive morphine-treated groups. We use opioids to treat procedural or post operative pain but do not routinely use continuous opioid infusions for all ventilated preterm neonates. Morphine infusions should be used cautiously with extreme prematurity or preexisting hypotension. Analgesics or sedatives which have less cardiovascular effects, such as fentanyl or ketamine, may be better alternatives if required in these neonates.
II. PRINCIPLES OF PREVENTION AND MANAGEMENT OF NEONATAL PAIN AND STRESS
A. Principles of pain management in newborns include the following:
Neuroanatomic components and neuroendocrine systems of the neonate are sufficiently developed to allow transmission of painful stimuli.
Exposure to prolonged or severe pain may increase neonatal morbidity.
Infants who have experienced pain during the neonatal period respond differently to subsequent painful events.
Severity of pain and effects of analgesia can be assessed in the neonate using validated instruments.
Newborn infants usually are not easily comforted when analgesia is needed.
A lack of behavioral responses (including crying and movement) does not necessarily indicate the absence of pain.
B. Current American Academy of Pediatrics (AAP) recommendations for assessment and management of pain and stress in the newborn should be followed.
Assessment of pain and stress in the newborn. Newborns should be assessed for pain routinely, and before and after procedures, by caregivers who are trained to assess pain using multidimensional tools. The pain scales that were used should help guide caregivers to provide effective pain relief. Because small variations in scoring points can result in undertreatment or overtreatment, the proficiency of individual caregivers using the chosen pain scale should be reassessed periodically to maintain reliability in assessing pain. A video and case scenario is helpful.
Reducing pain from bedside care procedures a.Laboratory tests or procedures should be reviewed daily to reduce the number of unwarranted skin punctures and painful tests.
b. The combination of either oral sucrose or glucose, breastfeeding, and other nonpharmacologic pain-reduction methods (nonnutritive sucking, kangaroo care, hand containment or facilitated tuck, and swaddling) are evidence-based interventions that reduce the pain response to heel stick or acutely painful events.
c. Topical anesthetics can be used to reduce pain associated with venipuncture, lumbar puncture, and intravenous (IV) catheter insertion when time permits but are ineffective for heel-stick blood draws, and repeated use of topical anesthetics should be limited.
Reducing pain from surgery. Anticipation and planning for pain management is essential to the success of any pain management program. Information aids the planning process and includes postmenstrual age (PMA), acuity, comorbidities, type of procedure or surgery, and respiratory support along with standard hand-off communication to reduce variation in pain management.
a. Health care facilities providing surgery for neonates should establish a protocol for pain management in collaboration with anesthesia, surgery, neonatology, nursing, and pharmacy. Such a protocol requires a coordinated, multidimensional strategy, and a priority in perioperative pain management.
b. Sufficient anesthesia and analgesia is provided to prevent intraoperative pain and stress responses and decrease postoperative analgesic requirements.
c. Surgical pain requires both preplanning and a well-defined “hand off” from physician to physician and recovery or operating room (OR) nurse to the NICU nurse. With specific attention to a review of medications received in the OR or recovery, a preemptive approach to pain management is more likely to succeed. Utilizing a written tool for the “hand off” report may decrease confusion from misinterpreted or lost information and delays in postoperative analgesia.
d. Pain is routinely assessed using a valid, reliable scale designed for postoperative or prolonged pain in neonates.
e. Opioids are the basis for postoperative analgesia after a major surgery in the absence of regional anesthesia. During the immediate postoperative period, opioids are most effective when scheduled at regular intervals. Although there is little evidence indicating a benefit of continuous opioid infusion over intermittent dosing, for safety and simplicity reasons, continuous infusions are recommended for major surgery in the neonate. Careful consideration to dosing and respiratory monitoring is essential. Dosing as needed (PRN) can lead to missed doses and fluctuating drug levels that do not provide adequate pain relief.
f. Postoperative analgesia is used for as long as pain assessment documentation indicates that it is required. Dosing intervals or dosages can be weaned if pain remains well controlled.
g. Elimination of opioids may be influenced by enterohepatic recirculation and elevated plasma concentrations, so monitoring for side effects should be maintained for several hours after opioids are discontinued.
h. Acetaminophen is sometimes used after surgery as an adjunct to regional anesthetics or opioids, but there are inadequate data on pharmacokinetics at gestational ages <28 weeks to permit calculation of appropriate dosages. Acetaminophen significantly reduces the pain response to tissue excision and pain scores during circumcision in some studies. Analgesic efficacy is disputed in other reports where acetaminophen did not relieve acute pain during heel stick or the postoperative pain from cardiac surgery.
Reducing pain from other major procedures a.Analgesia for chest drain insertion comprises all of the following:
General nonpharmacologic measures
Systemic analgesia with a rapidly acting opiate such as fentanyl
Slow infiltration of the skin site with a local anesthetic before incision, unless there is life-threatening instability.
b. Analgesia for chest drain removal comprises the following:
i. General nonpharmacologic measures (especially positioning/swaddling) ii. Short-acting, rapid-onset systemic analgesia
c. Data show anesthetic drops, oral sucrose administration, and containment reduce the pain response to eye exams for retinopathy of prematurity. There are no data on the effects of bright lighting following dilatation for eye exams. A thoughtful approach to minimize discomfort after an exam may be to decrease lighting or shield the infant’s eyes from light for 4 to 6 hours.
d. Retinal surgery should be considered as a major surgery, and effective opiate-based pain relief should be provided.
III. EVALUATING NEONATAL PAIN AND STRESS.
A number of validated and reliable scales of pain assessment are available. Behavioral indicators (e.g., facial expression, crying, body/extremity movement), as well as physiologic indicators (e.g., tachycardia or bradycardia, hypertension, tachypnea or apnea, oxygen desaturation, palmar sweating, vagal signs), are useful in assessing an infant’s level of comfort or discomfort. Biochemical markers for pain and stress such as plasma cortisol or catecholamine levels are not typically used in the clinical setting but may be useful for research.
Physiologic responses to painful stimuli include release of circulating catecholamines, heart rate acceleration, blood pressure increase, and a rise in intracranial pressure. Because the stress response of the immature fetus or preterm infant is less robust than that of the more mature infant or child, gestational age at birth and PMA must be considered when evaluating the pain response. Among preterm infants who are experiencing pain, a change in vital signs associated with the stress response (e.g., tachycardia, hypertension) and agitation are not consistently evident. Even among infants with an intact response to pain, a painful stimulus that persists for hours or days exhausts the sympathetic nervous system output and obscures the clinician’s ability to objectively assess the infant’s level of discomfort.
Changes in vital signs are not specific to pain and may be unreliable when used alone to identify pain. Changes in facial activity and heart rate are the most sensitive measures of pain that were observed in term and preterm infants. By 25 to 26 weeks,
the facial expression is the same as for children/adults. Before that, various facial components of a grimace may be observed separately such as eye squeeze. The premature infant pain profile (PIPP) scores the facial components separately to capture the lower birth weight infant who may be limited in the ability to produce and sustain a full grimace.
the facial expression is the same as for children/adults. Before that, various facial components of a grimace may be observed separately such as eye squeeze. The premature infant pain profile (PIPP) scores the facial components separately to capture the lower birth weight infant who may be limited in the ability to produce and sustain a full grimace.
A. Pain assessment. Selecting the most appropriate tool for evaluating neonatal pain is essential to its management. Documentation of pain is just as crucial. In general, pain scores that are documented along with vital signs can be monitored more easily for trends and subtle patterns so pain, unrelieved pain, or opioid tolerance can be identified early. Physicians, nurses, and parents express different perceptions of pain cues when presented with the same infant pain responses. A caregiver’s bias can influence both judgment and action when they are evaluating and treating pain. A pain-scoring tool with appropriate age range, acceptable psychometric properties, clinical utility, and feasibility may reduce bias even though none is perfect. Many tools exist and a few of the more common ones are shown in Table 67.1.
Table 67.1 Examples of Neonatal Pain Scoring Tools with Acceptable Psychometric Data | ||||||||||||||
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