Methods of Assessing Pain in the Newborn
Assessing neonatal pain appropriately is a vital step in providing adequate management of pain. Accurate assessment of pain is challenging in the neonatal population for several reasons. The most obvious is the neonate’s inability to verbalize the exact location and intensity of pain along with other verbal descriptors adult patients are able to provide to direct pain management. Gestational age and maturity also inhibit the neonate’s ability to provide physiological and physical cues of pain. Because of the subjective nature of pain, the level of skill of the health care worker contributes or detracts from recognizing and assessing pain cues. Subjective observations can change relative to the pain assessment tool used for a particular neonatal environment. A review of physiological cues of neonatal pain beginning with a term newborn through gestational ages in 2-week increments provides a deeper understanding of the presentation of pain symptoms of neonates.
Term, healthy newborns possess a mature neurological system with myelinated neuronal pathways of the neospinothalamic and paleospinothalamic tracts and relatively well-functioning pathways and perceptions (Lowery, Hardman, Manning, Whit Hall, & Anand, 2007). Myelination is sufficiently mature in the sensory, cerebellar, and extrapyramidal tracts, for involuntary reflex and movement for perception and response to painful stimuli. The term newborn’s neurological system has an adequate capacity to perceive and respond to tactile stimulation, including pain. Areas most sensitive and thus most mature in term newborns are the face, hands, and soles of the feet. With the capacity to perceive and respond to pain, the term newborn does so through physiological and behavioral cues.
Physiological cues of a healthy term newborn include hormonal, metabolic, and cardiorespiratory changes (Bouwmeester, van Dijk, & Tibboel, n.d.). Hormonal changes affecting cortisol levels vary by gestational age, but tend to fluctuate the least in term newborns (Grunau, 2013). Cortisol levels are important for the newborn’s ability to regulate glycolysis and glucose homeostasis. Increasing stress from unrecognized and unmanaged pain will result in cortisol abnormalities even in the healthy term newborn (Heckmann, Wudy, Haack, & Pohlandt, 1999).
Metabolic changes that occur in newborns with poorly managed pain include a propensity for catabolic metabolism. Protein breakdown increases, which contributes to reduced healing capacity. Abnormal nutrient absorption occurs, which contributes to metabolic dysfunction and glucose instability, both of which increase morbidity and mortality from unmanaged pain (Matthew & Matthew, 2003).
Cardiorespiratory changes frequently seen in neonates experiencing pain include bradycardic episodes, decreased oxygenation, ventilation-perfusion mismatch, and increased oxygen consumption. Each of these changes contributes to detrimental outcomes for the infant, ranging from neurological deficits to organ dysfunction.
Bradycardic episodes decrease total circulating volume, reducing perfusion and oxygen delivery to vital organs and tissue. Gastrointestinal perfusion is most significantly affected, compromising digestion and peristalsis. Severe and prolonged bradycardic episodes can lead to reduced renal perfusion, compromising acid–base balance, and clearance of toxins and waste.
Decreased oxygenation and ventilation–perfusion mismatch leads to decreased availability of oxygen at a cellular level, compromising oxygen delivery to tissues and vital organs. Again, gastrointestinal function is most affected, contributing to microscopic areas of infarct, which can contribute to collectively larger areas of infarct and necrotizing enterocolitis. Decreased availability of oxygen is known to lead to cerebral damage and potentially lifelong neurological deficits (Ball & Bindler, 2007; Kenner & Lott, 2003).
The perception of and response to pain increases metabolic energy demands, increasing the cellular need for oxygen availability. When oxygen availability is reduced as a result of bradycardic episodes, the capacity to maintain a higher metabolic energy load is decreased. Increasing oxygen needs with decreasing oxygen availability creates a negative scenario for metabolic and physiologic stability. The infant will resort to anaerobic metabolism at a much quicker rate, increasing lactic acid levels and increasing risks related to anaerobic metabolism (Ball & Bindler, 2007).
As the gestational age of the infant decreases, so does the physiological maturity of the newborn, which, in turn, affects the infant’s ability to process and respond to painful stimuli. With each 2-week decrease in gestational age, the capacity of the neonate to maintain physiological stability decreases. The 36- to 38-week-gestation infant has a decreased capacity to maintain cardiorespiratory function with relation to pain, reducing the ability to maintain oxygenation and perfusion. Cortisol levels become increasingly higher, resulting in decreasing glucose stabilization. Catabolic metabolism increases, resulting in greater protein synthesis (Kenner & Lott, 2003).
Subjective observations of neonatal pain focus on the behavioral cues infants present when experiencing pain. Behavioral cues include a spectrum of behaviors, again influenced by gestational age and neurological maturation and capacity to express behavioral changes. The key behavioral cues infants demonstrate when experiencing pain include irritability, posturing, grimacing, eye squeezing, curled tongue, and stretched open mouths (Schellack, 2011; Tietjen, 2001). As gestational age decreases, the ability of the neonate to manifest these behaviors decreases.
Assessment tools are available that recognize and quantify the physiological and behavioral observations as pain values. Each tool uses a variety of assessment parameters and foci to determine a particular pain range so the practitioner can decide on the intervention that best meets the neonate’s needs. Each tool provides a comprehensive, complete range for assessing pain; one must use caution in understanding the patient population one is working with to ensure the most appropriate tool is selected.
The CRIES (or crying requires increasing oxygen administration, increased vital signs, expression, sleeplessness) tool, shown in Table 2.1, was developed by a neonatal clinical nurse specialist in Columbia, Missouri, for assessing and measuring neonatal postoperative pain. The tool is appropriate for use with infants 6 months or younger in postoperative intensive care units and pediatric care units. Point values are assigned to assessment criteria for each of the areas identified through the CRIES acronym.
Using CRIES begins with an assessment of crying. Understanding that crying is a normal activity of infants, the presence of a high-pitched cry is typically characteristic of pain. The tool requires the practitioner to evaluate the cry and assign a point value based on the characteristics of the cry. Crying is assessed as either not crying, crying but not high pitched, high-pitched crying but consolable, and inconsolable crying. Zero points are awarded for no crying and crying that is not high pitched. One point is awarded for the high-pitched, consolable cry, and two points for inconsolable crying (Krechel & Bindler, 1995).
Alterations in oxygenation determined by pulse oximetry measurement can be related to many things, such as hypoxemia, oversedation, or pulmonary dysfunction. First ruling out alternate causes for changes in oxygenation leads the practitioner to evaluate changes relative to pain. Oxygen consumption increases when pain is experienced, causing the infant to present with decreased oxygen levels. Oxygen requirements are evaluated in three increments with relative point values. Zero points are assigned when no change in oxygenation is noted and no supplemental oxygen is required. One point is awarded when less than or equal to 30% supplemental oxygen is required to maintain oxygen saturation greater than 95%. Two points are lawarded when less than or equal to 30% supplemental oxygen is required to maintain oxygen saturation greater than 95% (Krechel & Bindler, 1995).
When assessing the vital signs of a previously stable neonate, increasing vital signs’ values from pre-operative baseline values indicates an increase in pain. Zero points are assigned when the heart rate and mean blood pressure are less than or equal to the preoperative baseline vital signs. One point is awarded when the heart rate or mean blood pressure increases by less than or equal to 20% from preoperative baseline values. Two points are awarded when the heart rate or mean blood pressure increases greater than 20% from preoperative baseline values. To calculate the evaluation percentage, the baseline heart rate is multiplied by 0.2, and then added to the total baseline value.
Expression assesses behavioral changes with which the infant may present. No expressions, or relaxed, calm facial expressions are awarded zero points. Grimacing receives one point and grimacing with grunting is awarded two points. Grimacing is indicated by a lowered brow, eyes squeezed shut, a deepening of the nasolabial furrow, and open lips and mouth.
Determination of sleeplessness is the last assessment criterion for the CRIES tool. Infants not experiencing any sleeplessness receive zero points. Infants waking at frequent intervals and not enjoying continuous sleep receive one point. Infants who are constantly awake and not enjoying any sleep periods receive two points.
Point values are added from all assessment parameters to create a total score ranging from 0 to 10. The higher the score the infant receives, the greater the subjective assessment of pain expression. Working collaboratively, the health care team determines interventions with the families, if appropriate, in response to the scores (Krechel & Bindler, 1995). A standardized approach to interventions based on scores is imperative prior to using the CRIES tool to ensure consistency and compliance (Krechel, 1995).
TABLE 2.1 CRIES Pain Scale
NEONATAL INFANT PAIN SCALE
The Neonatal Infant Pain Scale (NIPS), as shown in Table 2.2, is a behavioral assessment tool for measuring pain in full-term and preterm infants. Eight indicators assess behaviors believed to be indicative of infant pain and include facial expressions, cry, breathing patterns, arms, legs, and state of arousal. Each indicator has several assessment criteria with point values awarded for each finding. Beginning with facial expression, an infant is assessed as relaxed with a restful, neutral expression, which generates zero points, or grimacing. Grimacing facial expressions are considered to be tight facial muscles, a furrowed brow, chin, and/or jaw, and receive one point.
Crying is assessed as three separate states. No crying, meaning the infant is quiet and calm, receives zero points. Whimpering, mild moaning, and intermittent sounds of discomfort receive one point. Vigorous crying with loud, shrill, continuous screaming receives two points. An infant who is intubated and crying “silently” can be awarded cry points based on visual assessment of facial expressions and behaviors regardless of sound.
TABLE 2.2 Neonatal Infant Pain Scale (NIPS)
Breathing patterns are assessed as relaxed and usual for the infant being assessed, or as changes in respiration. The infant without any change in normal respiratory movements and patterns receives zero points. The infant with irregular breathing, such as tachypnea, bradypnea, gagging, or apnea, receives one point.
Assessment of arms and legs provides two areas of evaluation and point assignment. Relaxed, smooth movements of arms and legs with no muscle rigidity or posturing noted in either extremity receive zero points for each limb. Infants who hold arms or legs with rigid extension or flexion receive one point for extension of any one of the extremities.
An assessment of the state of arousal again awards the infant zero or one point, based on the assessment findings. An infant who is quietly sleeping or is awake and alert but settled and quietly observing the environment receives zero points. An infant who is fussing, restless, fidgeting, and unable to quietly observe the environment while awake receives one point.
For point value consideration, assessment of heart rate and oxygen saturation require baseline vital signs for comparison. The infant whose heart rate remains within 10% of the documented baseline at all times receives zero points. The infant who requires no supplemental oxygen to maintain oxygen saturation receives zero points. The infant whose heart rate falls within 11% to 20% of the baseline vital signs receives one point. The infant who requires any additional supplemental oxygenation to maintain oxygen saturations at baseline receives one point. The infant whose heart rate exceeds 20% of the documented baselines receives two points, as shown in Table 2.2.
When assessment of the eight criteria is completed, the points awarded are tallied for a total score, indicating a pain level for that individual infant. Any infant scoring greater than three points is considered to be experiencing pain. Practitioners and clinicians need to agree on a comprehensive protocol for interventions to manage pain in increments based on the scores assessed for each infant. A point to consider when using the NIPS assessment tool is not every neonate will have the capacity to present with the assessment criteria in the tool. Infants who are experiencing severe or overwhelming sepsis and/or are receiving paralytic agents as a treatment are unable to manifest the symptoms the clinician is seeking to find. Consideration of contributing factors that will alter the final score are necessary for final pain score determination (Alcock, 1993; Gallo, 2003).
NEONATAL PAIN, AGITATION, AND SEDATION SCALE
The Neonatal Pain, Agitation, and Sedation Scale (N-PASS) is a tool used to measure pain in term and preterm infants who are experiencing prolonged postoperative pain and/or pain during mechanical ventilation. The tool uses five physiological and behavioral cues with relative validity for measurement (Hummel, Puchalski, Creech, & Weiss, 2008). The tool uses an ordinal system for point assessment, with values ranging from minus two to two. N-PASS also considers sedation as an assessment parameter, as shown in Table 2.3. Beginning with crying and irritability, the practitioner first considers the state of sedation of the infant based on pharmaceutical delivery and considers whether the infant has no cry with painful stimuli, and, if so, awards minus two points. The infant who is sedated and elicits minimal moaning or crying with painful stimuli is awarded minus one point. An infant displaying appropriate crying for the situation and is not irritable receives zero points. The infant who is irritable or crying intermittently yet is consolable will receive one point. The infant experiencing high-pitched crying that is continuous or who is intubated and experiences silent continuous crying and is inconsolable will receive two points.
Table 2.3 shows assessment of the behavior state again begins with consideration of the sedation state with minus two points awarded to the infant who exhibits no arousal to any stimuli and exhibits no spontaneous movements. The infant who is sedated and can exhibit minimal arousal to stimuli and has little spontaneous movement will receive minus one point. An infant whose behavior state is appropriate for gestational age receives zero points. The infant who is restless, squirming, and awakens frequently between sleep cycles will earn one point. The infant who is arching, kicking, constantly awake with no sleep cycles or arouses minimally with no movement without sedation is awarded two points (Hummel et al., 2008).
Evaluation of facial expressions begins again with consideration of sedated state, with minus two points awarded when the infant expresses a lax mouth with no expression and minus one point when exhibiting minimal expressions with stimulation. The normal, nonsedated infant experiencing no pain who is relaxed and appropriate for gestational age receives zero points. When evaluating the infant, discovery of any pain expression, even intermittently, earns the infant one point. The infant expressing continual pain through facial expressions receives two points.
Extremities are assessed for reflex expression and tone, as well as posturing behaviors using N-PASS. An infant who is sedated and demonstrating no grasp reflex and whose muscle tone is flaccid will earn minus two points. If the infant is sedated and can demonstrate a weak grasp with decreased muscle tone, minus one point is awarded. The infant without sedation who has relaxed hands and feet with normal tone will earn zero points. The infant who exhibits intermittent clenched toes, fists, or demonstrates finger splaying but whose body is not tense will earn one point. The infant who is continually clenching fists or toes and splaying fingers while also holding his or her body tense will earn two points, as shown in Table 2.3.
TABLE 2.3 N-PASS Pain Scale
When evaluating vital signs with N-PASS, assessment of heart rate, respiration, blood pressure, and pulse oximetry are necessary. The sedated infant who shows no variability from baseline with any stimuli or is hypoventilated or experiencing apneic episodes will earn minus two points. The sedated infant who experiences up to but less than 10% variability from baseline vital signs with any stimuli earns minus one point. The infant who enjoys vital signs that remain within baseline for gestational age receives zero points. The infant who has an increase in baseline vital signs from 10% to 20% and exhibits pulse oximetry readings between 76% and 85% with quick recovery with stimulation earns one point. The infant who exhibits an increase in vital signs greater than 20% from baseline with pulse oximetry readings equal to or less than 75% and is slow to recover or is out of synchronization with ventilator support earns two points (Hummel et al., 2003).
When all assessment criteria in all areas are complete, a number value is calculated. To ensure premature infants’ pain is adequately captured using N-PASS, providers compensate for decreased capacity of the infant to exhibit physiological and behavioral cues by adding points to the total score. For infants less than 28 weeks gestation, the practitioner must add three points; for the infant less than 28 to 31 weeks gestation, add two points; and the infant less than 32 to 35 weeks gestation, add one point to the total score. The total score is documented as a whole number ranging from 0 to 10. The infant is considered to be experiencing pain that requires intervention when scores exceed a value of three. The goal is to maintain total pain scores below three for any infant. Interventions and management of scores greater than three will require a collaborative and comprehensive intervention plan that is adhered to for all infants (Hummel et al., 2003).
PREMATURE INFANT PAIN PROFILE