From the day they are born, infants, including premature babies, can feel and express pain. Over the years, heath care experts have learned to assess pain in newborns.
An assessment of pain in babies relies mostly on observing behaviours. For example, newborns can respond to painful events such as a heel prick within the first minutes of life.
In addition to noting behavioural changes that might indicate pain, there are physiological measures that can be used to assess pain in premature and newborn babies. These include temperature, blood pressure, heart rate, and oxygen consumption, among others.
The situational context is also taken into account when assessing pain. In the case of premature babies, gestational age and the infant’s sleep and waking states are important in this regard.
Although there are established and proven methods to assess pain in premature babies, pain assessment is not an exact science. To lessen the guesswork, pain assessment tools, which are generally checklists of possible pain indicators, take into account behavioural, physiological, and contextual measures. However, it should be noted that changes in behaviour and physiology can be due to other factors.
Behaviour in response to pain
Premature babies in pain tend to display pain in their facial expressions, arm and leg movements, and cries. They may try to guard or protect a sore part of their body or even pull on it. Changes in eating, moving, and sleeping can also be indicators of pain.
Facial expressions are generally regarded as the best single behavioural indicator of pain in all age groups. A grimace, eyes squeezed shut and mouth stretched open with a tensed and curled tongue, are common expressions of pain.
Babies cry for reasons such as hunger, anger, or fear, but the cries of pain are distinctive. The typical pain cry is high-pitched, tense, harsh, non-melodious, sharp, short, and loud. However, the absence of crying does not mean a baby is not in pain. An infant in severe pain may not cry at all, especially if he is very premature. He may simply not have the energy to cry.
Premature and very young babies may not move and may become still in response to pain. This absence of movement has also been noted in older children recovering from surgery. They recognize that moving hurts and so remain still to minimize the amount of pain.
Assessing an infant’s pain by observing takes skill and requires an understanding of infant development. This is why no single measure is used exclusively. Several measures are used to make a determination of pain.
Physical reactions to pain
Physiologic indicators, including heart rate, breathing rate, blood pressure, skin colour, vomiting, sweating, and dilatedor widened pupils, are also used to determine if an infant is in pain. Because changes in these indicators can result from other causes, including physical stress, fear, or anxiety, they can be difficult to interpret. Despite these limitations, when used with behavioural and contextual indicators, these signs can be useful as part of an overall assessment for a baby in pain.
In addition to behavioural and physical reactions to pain, a baby’s context will also be taken into account when assessing pain. For example, when multiple procedures are going on, sometimes a premature baby will respond with an exaggerated response to pain or may painfully respond to non-painful procedures. Other premature babies may become limp and cease responding to repeated painful procedures. Studies are underway to determine why premature babies tend to respond one way or the other.
A premature baby’s gestational age can also influence pain. In general, extremely premature infants tend to have less response to pain compared to older premature babies. However, this does not necessarily mean they are feeling less pain.
Neurologically impaired babies, that is to say babies who have sustained some degree of brain damage, show less behavioural and physiological response to pain. Again, this does not mean they don’t have pain.
Time and experience can also be contextual factors that influence pain. For example, if a premature baby has had to endure multiple painful procedures, over time his response to the next painful procedure is often reduced.
How well and how much a premature baby sleeps can also be an indication of pain. This is another area that is currently being studied.
Common events and conditions that cause pain
In the NICU, pain is experienced either through procedures or because of conditions and injuries.
Common painful procedures include heel pricks or needles, intravenous insertions, suctioning of mouth and nose, lumbar punctures, and intramuscular injections.
Common painful conditions include severe intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), burns, skin conditions, surgery, and fractures.
Pain assessment tools for premature babies
Premature Infant Pain Profile (PIPP)
PIPP is a comprehensive assessment tool used for newborn babies born either at term or preterm. A newborn infant's pain intensity is determined by measuring behavioural indicators such as facial expressions, physiological indicators such as heart rate and oxygen level in the blood, and considering them along with contextual indicators such as the child's gestational age at birth as well as her sleep/wake state. These indicators are scored together to provide an indication of acute pain.
Other pain assessment tools
In addition to PIPP, other pain assessment tools can be used to help determine how much pain a premature baby is experiencing. These include:
- the Neonatal Facial Coding Scale (NFCS)
- the Faces, Legs, Activity, Cry, and Consolability Scale (FLACC)
- the Neonatal Infant Pain Scale (NIPS)
- the CRIES Score
In general, all of these tools use similar behavioural, physiological, and contextual markers to assess pain in premature babies.