Increased Risk of Postthoracotomy Pain Syndrome in Patients with Prolonged Hospitalization and Increased Postoperative Opioid Use

The Effect of Epidural Infusion of Dexmedetomidine on Postoperative Analgesia After Thoracotomy: A Randomized Clinical Trial

Background

The unique analgesic properties of dexmedetomidine have led anesthesiologists to use it as an alternative to relieve pain after major surgeries.

Objectives

We aimed to evaluate the effect of continuous injection of thoracic epidural dexmedetomidine on analgesia after thoracotomy.

Methods

In this randomized, double-blind clinical trial, 46 patients (18 to 70 years old) who were candidates for thoracotomy surgery were randomly assigned to receive ropivacaine alone or combined with dexmedetomidine after epidural anesthesia as postoperative epidural anesthesia. The postoperative sedation rate, pain score, and opioid use were assessed within 48 hours after surgery and compared between the 2 groups.

Results

Comparing the mean postoperative sedation scores indicated no difference between the 2 study groups. The pain score assessment showed a lower pain score 6 to 36 hours after surgery in the group receiving concurrent ropivacaine and dexmedetomidine than in the group receiving ropivacaine alone. In the 2 groups receiving ropivacaine with and without dexmedetomidine, the rate of morphine administration after surgery was 43.4% and 65.2%, respectively, indicating no difference. However, the first group received significantly lower doses of morphine after the end of surgery (3.26 ± 0.90 mg vs. 7.04 ± 1.48 mg; P = 0.035).

Conclusions

A combination of ropivacaine and dexmedetomidine as epidural analgesia can lead to lower postoperative pain scores and reduced doses of opioids required.

Chronic postsurgical pain: is there a possible genetic link?

Persistent or chronic postsurgical pain (CPSP) has been defined as 'pain persisting beyond 2 months'. The cut-off limit of 2 months has been controversial, and some researchers argue for a 3-month period for the definition of CPSP. Multiple mechanisms, including both patient and surgical, have been shown to influence this transition. Patient factors include age, gender, anxiety, depression, somatisation, catastrophising, pre-existing pain anywhere and pain at the site of surgery. The various surgical factors include site and nature of surgery, infection, inflammation and repeat surgery. There is evidence that pre- or post-op chemotherapy and radiotherapy can also contribute towards the chronification of pain after surgery. The question of why pain following surgery or trauma persists long after the normal healing time is not yet fully explained by current evidence. This is frustrating to healthcare providers and intensely disappointing to the patients, many of whom suffer in silence for years. Genetics is now being shown to influence both the onset and the perpetuation of chronic pain in the susceptible patient. The main mechanisms are believed to be 'single nucleotide polymorphisms' (SNPs) and 'epigenetics', both of which will be discussed, with current and ongoing research and evidence, in this review. The influence of SNPs has not been replicated in recent studies and researchers advise caution in interpreting past studies. More research is needed to demonstrate the involvement of epigenetics as well as linking SNPs to the susceptible patient's journey.