**1.3. Impacts of poorly managed acute pain**

For more detailed information, please review "The Basic Science of Pain" by Philip Peng (https://

itunes.apple.com/ca/book/the-basic-science-of-pain/id1174147456?mt=11).

**Figure 1.** Simplified acute pain pathways.

68 Pain Relief - From Analgesics to Alternative Therapies

**Figure 2.** Simplified chronic pain pathophysiology.

When acute pain is not well-managed, deleterious effects on physiology, functional recovery and psychology can develop. Changes include increased morbidity such as nausea, emesis, poor oral fluid intake, sleep disturbance and behavioural changes. Ongoing discomfort and distress have a negative impact on child and family satisfaction and may be associated with poor recovery, anxiety, fear and reduced quality of life measures [64–71].

Physical and psychological responses to pain not only affect children's health directly but may also predispose them to develop chronic post-surgical pain (CPSP). Chronic pain affects approximately 20% of the adult population of which 22.5% develop their condition after surgery [72]. CPSP occurs following 10–50% of adult operations in which 2–10% of these adult patients will experience severe chronic pain [73]. The incidence of CPSP in the adult population is found to depend on a number of perioperative factors, which include genetic predisposition, younger age, degree of pre-operative anxiety, degree of catastrophization, depression, pre-operative pain status, the surgical pain model, surgical technique, length of surgery and the quality of acute post-operative pain management [73–76]. CPSP will often be neuropathic, resulting from nerve damage during surgery. CPSP studies in children are limited with a preliminary incidence of CPSP reported as 13–25% [77–80]. Prospective studies after spine surgery have also demonstrated prevalence rates of CPSP between 11 and 22% with risk factor for development of CPSP including high levels baseline pain intensity, anxiety and older age [81–83]. Recently, Rabbitts et al. found two distinct pain trajectories following major surgery in children; most children follow a positive early recovery pathway, whereas 22% follow a late recovery trajectory. One of the factors of the late recovery group was the presence of baseline parental catastrophizing (not child/youth catastrophizing) [84]. Nikolajsen and Brix also identified factors for risk of CPSP in children as older age, pre-op pain, acute postoperative pain and psychological factors, especially anxiety [85]. Some of these children/youth will go on to develop chronic pain in adulthood [86]. All these complications of poorly managed acute pain ultimately increase healthcare utilization and have an economic cost for both families and the health-care service. It is, therefore, essential to minimize post-surgical pain to prevent pain-related complications. This may be achievable with the adoption of preventative multimodal analgesia to minimize nociceptive traffic and reduce wind up and central sensitisation.
