Pain management and surgical outcomes

Whilst surgeons and anaesthetists over the years have understood the importance of optimising perioperative pain management, it is only relatively recently that real exploration of the topic of perioperative pain and outcome has gained prominence. 

There are two main areas of consideration in this topic that need distinguishing:

1. Does optimising perioperative pain management affect all surgical outcomes?
2. Does optimising perioperative pain management affect pain outcomes? In other words, does good pain management reduce patient risk of persistent post-surgical pain syndromes?

Does pain affect outcome from surgery?

There is a body of high-level evidence showing that poor postoperative pain management affects most of the post-surgical domains.  Negative effects have been shown on length of stay, sleep disturbance, prolonged time to mobilisation, delirium in the elderly and cardiopulmonary complications to name but a few¹.

Unsurprisingly, it is additionally relatively easy to pick who will be affected.  Evidence shows that worst pain score at day 10 is an independent predictor of time taken for complete surgical recovery².

Persistent post-surgical pain

Roughly 25% of a chronic pain clinic’s work is chronic post-surgical pain (CPSP), even excluding the relative crises of Complex Regional Pain Syndrome. 

Predominantly neuropathic in character, CPSP is diagnosed at 2 months post-surgery and is surprisingly common.  The incidence ranges according to the surgery but even minor surgeries like hernia surgery carry a 4% risk of severe CPSP, increasing to the more obvious surgeries such as post knee arthroplasty with a 15% risk, 10% post mastectomy and even higher post thoracotomy³.

The risk factors for post-surgical pain include patient related factors such as anxiety, treatment factors i.e., the need for pre/post-operative chemo or radiotherapy or repeat surgeries.  By far however, the biggest risk factors are poorly controlled pain pre, peri and post-operatively.  The challenge with management of CPSP is in managing it effectively and quickly to obtain a good prognosis and avoid the not infrequent and dire cases where the syndrome becomes intractable.  That in turn prevents the spiral into mood disruption, dissatisfaction with treatment providers and all the challenges of chronic pain management.

The common solution

The main goals of pain management in this situation are prevention and then early and progressive treatment should it occur.  This is true for aiding immediate surgical outcome or identification of the start of CPSP and then management.

Prevention

Maintaining a high index of suspicion and regularly assessing our patients is the fastest way to identify those at risk.  Working with pain specialists engaged in this topic will aid risk stratification from the time of decision to operate, throughout the operative period and beyond.  

For instance, if we can develop alert systems to pick up the anxious patient having further breast surgery and chemo or the depressed, isolated revision knee replacement patient already on high dose opioids, at booking, we can then:  

• allow our pain and anaesthetic colleagues to engage pre-operatively for peri-op planning
• manage intensively perioperatively
• identify, diagnose and follow up early post. 

Management of post-surgical pain syndromes

In brief, a pain specialist will assess the relative contributions of neuropathic and nociceptive pain and use the full range of medication, interventional, psychological and physical options to try and prevent the decline to intractable pain; always so much harder to treat.  As with all chronic pain syndromes the patient should have all domains of pain assessed and managed.  ​​​​​​

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References:
1.    Yang MH et al. Preoperative predictors of poor acute postoperative pain control: a systematic review and meta-analysis. BMJopen 2019
2.    Hah J et al, Factors associated with acute pain estimation, postoperative pain resolution, opioid cessation and Recovery Jamanetworkopen 2019
3.    Schug S et al, Risk stratification for the development of chronic postsurgical pain. Pain Reports Nov 2017