Strong synthetic opioids linked to poor postoperative pain experience

The use of powerful synthetic opioids, such as sufentanil and remifentanil, during surgery is linked to a subsequent poor 'pain experience'---a composite of emotional, cognitive, and physical aspects of pain- suggests research published in the open access journal Regional Anesthesia & Pain Medicine.

The findings highlight the need to reassess intraoperative pain relief strategies to reduce complications after surgery and improve the quality of patient care, say the researchers.

Most patients experience moderate to severe pain after surgery, which is not only unpleasant for them, but can also hinder their recovery and increase their chances of subsequent complications, explain the researchers. 

Recent research suggests that the experience of pain encompasses more than intensity alone, and includes emotional and cognitive dimensions, they add. 

To identify factors potentially associated with poor 'pain experience' after surgery they carried out a secondary analysis of a clinical trial aimed at evaluating the effectiveness of sedatives given before surgery on the entire surgical experience.

The trial involved 1062 adults under the age of 70 at 5 French teaching hospitals. They had been randomly assigned the day before surgery to receive either lorazepam (sedative), nothing, or a dummy drug. 

Preoperative anxiety was assessed using a validated scale (APAIS), which measures anxiety about anesthesia and surgery as well as the patient's desire for information about the procedure.

Pain, sleep quality, and wellbeing were assessed using the Visual Analogue Scale (VAS), which measures the frequency and intensity of pain, while patient experience and satisfaction were measured the day after surgery using the EVAN-G questionnaire, which covers 26 items across dimensions.

For the current study, 971 patients with EVAN-G scale scores were included in the analysis. This showed that 271 (28%) reported a poor pain experience on the first day after surgery.

Influential factors included age, an APAIS score above 11, VAS scores for pain, sleep quality and wellbeing, tobacco use, long term opioid use and type of surgery. 

But the use of strong opioids, such as remifentanil or sufentanil, during general anaesthesia was strongly and independently linked to postoperative pain experience, with these patients almost 27 times as likely to report a poor one.

Patients given postoperative drugs to treat anxiety and those who reported amnesia were, respectively, 8 times and 58% more likely to have a poor pain experience the day after surgery, while higher VAS acute pain, and lower wellbeing, scores on day 1 were also predictive. 

Older age was associated with a lower likelihood of poor pain experience as were no preoperative sedative use and orthopedic surgery-51% and 71% lower, respectively-seriously ill patients with an ASA 3 score, as defined by the American Society of Anesthesiologists, were 5 times more likely to report poor pain experience.

This is an observational study, and as such, can't establish cause. And the researchers acknowledge the lack of standardised anesthesia and pain relief protocols across the different hospitals, which may limit the generalisability of the findings. 

"While opioids are central to perioperative analgesia, their intraoperative administration-especially of potent agents like remifentanil and sufentanil-may paradoxically contribute to heightened postoperative pain," note the researchers, by way of an explanation for their findings.

They conclude: "Aspects of pain beyond its intensity "are often overlooked, but…are critical in predicting the transition from acute to persistent postsurgical pain. 

"Therefore, understanding the determinants of a poor pain experience could reveal new elective targets for perioperative care, going beyond the management of pain intensity alone."