Infants and children require needle-related painful procedures for scheduled childhood immunisations (PHA Canada 2014) as well as medical procedures performed for diagnostic and treatment purposes during the course of childhood illnesses (Johnston 2011). Such procedures are known to be painful, causing distress at the time of the procedure and for many children, anxiety and fear during subsequent needle-related procedures (Schechter 2007; Taddio 2007; Taddio 2009; Wright 2009) and altered pain responses later in life (Taddio 2005). Fear of the pain associated with immunisations, with subsequent fear of needles, has been shown to be one of the reasons why parents do not complete their infants' recommended immunisation schedule (Mills 2005; Schechter 2007; Taddio 2007; Taddio 2009; Wright 2009). It is therefore imperative that effective pain management strategies be consistently used for infants and children in diverse settings where needle-related painful procedures are performed.
Recently conducted systematic reviews of pain management strategies in the newborn period demonstrated that breastfeeding (Shah 2012) and sweet solutions of sucrose (Stevens 2013) and glucose (Bueno 2013) reduced behavioural responses and composite pain scores during painful procedures. In addition, systematic reviews of sweet tasting solutions beyond the neonatal period up to one year of age, demonstrated analgesic effects during needle-related painful procedures when compared to water or no treatment (Harrison 2010a; Kassab 2012). Three published trials have also demonstrated analgesic effects of breastfeeding infants beyond the neonatal period, during scheduled childhood immunisation (Dilli 2009; Efe 2007; Razek 2009). There is a need for this evidence relating to analgesic effects of breastfeeding beyond the newborn period to be systematically reviewed on an ongoing basis to critically evaluate the effectiveness of this intervention in infants up to one year of age.
Description of the condition
As outlined above, healthy infants may experience multiple painful procedures during scheduled early childhood immunisations and during other medical procedures occurring over the course of childhood illnesses, and hospitalised infants undergo many more painful needle-related procedures over the course of their hospitalisation (Johnston 2011). Studies of pain management strategies used during commonly performed needle-related procedures consistently show inconsistent use of recommended interventions (Harrison 2013; Johnston 2011; Taddio 2007), yet it is known that untreated or poorly treated procedural pain has negative effects, including infant and parental distress at the time of the procedure, with the risk of longer term fear of needles (Schechter 2007; Taddio 1995; Taddio 2007; Taddio 2009; Wright 2009).
Description of the intervention
High quality evidence from randomised controlled trials (RCTs) and systematic reviews supports the role of breastfeeding in reducing procedural pain during the neonatal period (first 28 days of life). Shah et al. conducted a systematic review of 20 RCTs or quasi-RCTs evaluating breastfeeding (ten studies) or supplemental breast milk (ten studies) during heel lance or venipuncture in newborn infants (Shah 2012). The authors concluded that breastfeeding effectively reduced behavioural responses, including crying duration and total crying time, facial expressions and pain scores, as well the physiological response of heart rate, compared to positioning (swaddled and nursed in a crib), holding by the mother, placebo or no intervention. Effects of small amounts of supplemental breast milk however, were variable; breast milk given in small quantities failed to consistently reduce physiological or behavioural pain indicators or composite pain scores. This discrepancy may be due to the contribution of multiple factors influencing analgesia during breastfeeding other than taste alone, including maternal contact, skin-to-skin contact, familiar smell, sucking, and intake of naturally occurring endorphins present in the breast milk (Harrison 2010b; Zanardo 2001). As the sugar in breast milk is primarily lactose, the least sweet of the sugars (sucrose > fructose > glucose > lactose) (Blass 1992), the mildly sweet taste most likely contributes little to analgesia in isolation (eg delivered by oral syringe or via pacifier).
Studies have also evaluated breastfeeding for pain management in infants beyond the neonatal period during scheduled childhood immunisation (Dilli 2009; Efe 2007; Razek 2009). Results were comparable to the neonatal studies, showing a reduction in cry duration for infants in the breastfeeding group compared to being held by mothers, or simply swaddled and nursed in a crib. In 2009, Shah and colleagues, in a systematic review of strategies to reduce immunisation pain, included breastfeeding as one of the interventions (Shah 2009). They pooled results for cry duration from three studies (Dilli 2009; Efe 2007; Razek 2009), including 344 infants. Results showed a significant reduction in cry duration (weighted mean difference (WMD) -38 seconds (95% Confidence Interval (CI)) -42 to - 34 seconds). Thus, breastfeeding infants during immunisation and other painful procedures, when feasible, shows promise as an effective pain management strategy for infants up to one year of age.
How the intervention might work
There are several elements which are postulated to contribute to the analgesic effects of breastfeeding. These include: skin-to-skin contact; sight; sound and smell of the mother; sucking; distraction; pleasant, slightly sweet taste; and intake of naturally occurring endorphins that are present in breast milk (Blass 1995; Blass 1997; Shah 2012). As detailed in Shah 2012, breast milk also contains higher concentrations of tryptophan (Heine 1999), a precursor to melatonin, which in animal studies, has been shown to increase concentrations of beta-endorphin (Barrett 2000), a naturally occurring endorphin which is assumed to be one of the mechanisms responsible for the analgesic effects of breast milk.
Why it is important to do this review
Although a systematic review of breastfeeding newborn infants during painful procedures was shown to effectively reduce pain (Shah 2012), and a systematic review of multiple strategies to reduce immunisation pain, which included breastfeeding, also demonstrated analgesic effects of breastfeeding (Shah 2009), there is no current, ongoing systematic review of breastfeeding for pain management during all painful procedures beyond the neonatal period. This review is therefore important to further establish the effectiveness of this intervention in this population of infants. As infants usually become highly distressed during needle-related painful procedures, identifying and consistently using effective pain management strategies is important to the well-being of infants. If breastfeeding, when feasible, during painful procedures, consistently demonstrates analgesic effects in infants up to one year of age, it can be recommended as a simple, cost-effective and easily integrated strategy in diverse inpatient and outpatient settings (Razek 2009). If effective, this strategy has universal applicability, as it requires no additional cost, no special equipment and no special preparation or storage.