Chronobiological characteristics of postoperative pain: diurnal variation of both static and dynamic pain and effects of analgesic therapy

The disruptive relationship among circadian rhythms, pain, and opioids

Pain behavior and the systems that mediate opioid analgesia and opioid reward processing display circadian rhythms. Moreover, the pain system and opioid processing systems, including the mesolimbic reward circuitry, reciprocally interact with the circadian system. Recent work has demonstrated the disruptive relationship among these three systems. Disruption of circadian rhythms can exacerbate pain behavior and modulate opioid processing, and pain and opioids can influence circadian rhythms. This review highlights evidence demonstrating the relationship among the circadian, pain, and opioid systems. Evidence of how disruption of one of these systems can lead to reciprocal disruptions of the other is then reviewed. Finally, we discuss the interconnected nature of these systems to emphasize the importance of their interactions in therapeutic contexts.

Circadian pain patterns in human pain conditions - A systematic review

BACKGROUND

Chronobiology is the science of how physiological processes in the body follow a pattern of time. Pain has been shown to follow a circadian rhythm, with different types of pain having variable expression along this rhythm.

OBJECTIVE

This article reviews the nature of diurnal variations in pain along with a discussion of the mechanisms of circadian rhythm of pain.

EVIDENCE REVIEW

We conducted a literature search on the PubMed and Google Scholar electronic databases, through April 2022. Publications were screened for English language, full-text availability, and human subjects. Randomized controlled trials and observational trials were included. Data were extracted from studies on patients with acute or chronic pain phenotypes, which provide pain severity data and corresponding diurnal time points.

FINDINGS

The literature search led to the inclusion of 39 studies. A circadian pattern of pain was found to be present in nociceptive, neuropathic, central, and mixed pain states. Postoperative pain, fibromyalgia, trigeminal neuralgia, and migraines were associated with higher pain scores in the morning. Temporomandibular joint pain, neuropathic pain, labor pain, biliary colic, and cluster headaches increased throughout the day to reach a peak in the evening or night. Arthritis and cancer pain were not associated with any circadian rhythmicity. Furthermore, the circadian rhythm of pain was not found to be altered in patients on analgesics.

CONCLUSION

The results of this review suggest that an understanding of diurnal variation may help improve therapeutic strategies in pain management, for instance through analgesic titration.

A scoping review of the diurnal variation in the intensity of neuropathic pain

BACKGROUND

Recent studies suggest that neuropathic pain exhibit a daily diurnal pattern with peak levels usually in the late afternoon to evening and trough in the morning hours, although literature on this topic has been sparse. This scoping review examines current evidence on the chronobiology of neuropathic pain in both animal models and in humans with neuropathic pain.

METHOD

Literature search was conducted on major medical databases for relevant articles on chronobiology of neuropathic pain in both animal models and in humans with neuropathic pain. Data extracted include details of specific animal models or specific neuropathic pain conditions in humans, methods and timing of assessing pain severity, and specific findings of diurnal variation in pain intensity or its surrogate markers.

RESULTS

Thirteen animal and eight human studies published between 1976 to 2020 were included in the analysis. Seven out of 13 animal studies reported specific diurnal variation in pain intensity, with five of the seven studies reporting a trend towards increased sensitivity to mechanical allodynia or thermal hyperalgesia in the late light to dark phase. All eight studies on human subjects reported a diurnal variation in the intensity of neuropathic pain where there was an increase in pain intensity through the day with peaks in late evening and early night hours.

CONCLUSIONS

Studies included in this review demonstrated a diurnal variation in the pattern of neuropathic pain that is distinct from the pattern for nociceptive pain. These findings have implications for potential therapeutic strategies for neuropathic pain.

Current methods and challenges for acute pain clinical trials

This article reviews current methods and challenges and provides recommendations for future design and conduct of clinical trials of interventions to treat acute pain.

Introduction:

The clinical setting of acute pain has provided some of the first approaches for the development of analgesic clinical trial methods.

Objectives:

This article reviews current methods and challenges and provides recommendations for future design and conduct of clinical trials of interventions to treat acute pain.

Conclusion:

Growing knowledge about important diverse patient factors as well as varying pain responses to different acute pain conditions and surgical procedures has highlighted several emerging needs for acute pain trials. These include development of early-phase trial designs that minimize variability and thereby enhance assay sensitivity, minimization of bias through blinding and randomization to treatment allocation, and measurement of clinically relevant outcomes such as movement-evoked pain. However, further improvements are needed, in particular for the development of trial methods that focus on treating complex patients at high risk of severe acute pain.

Serial Analgesic Consumptions and Predictors of Intravenous Patient-controlled Analgesia with Cluster Analysis

Objectives:

To elucidate the dynamics of analgesic consumption regarding intravenous patient controlled analgesia (IVPCA) during postoperative period is rather complex partly due to between-patient variation and partly due to within-patient variation. A statistical method was proposed to classify serial analgesic consumption into different classifications that were further taken as the multiple outcomes on which to explore the associated predictors.

Methods:

We retrospectively included 3284 patients administrated by IVPCA for 3 days after surgery. A repeated measurement design corresponding to serial analgesic consumption variables defined as six-hour total analgesic consumptions was adopted. After determining the numbers of clusters, serial analgesic consumptions were classified into several homogeneous subgroups. Factors associated with new classifications were identified and quantified with a multinominal logistic regression model.

Results:

Three distinct analgesic classifications were aggregated, including “high”, ”middle” and “low” level of analgesic consumption of IVPCA. The mean analgesic consumptions on 12 successive analgesic consumptions at 6-hour interval of each classification consistently revealed a decreasing trend. As the trends were almost parallel with time, this suggests the time-invariant proportionality of analgesic consumption between the levels of analgesic consumption of IVPCA. Patient’s characteristics, like age, gender, weight, height, and cancer status, were significant factors associated with analgesic classifications. Surgical sites had great impacts on analgesic classifications.

Discussion:

The serial analgesic consumptions were simplified into 3 analgesic consumptions classifications. The identified predictors are useful to recognize patient’s analgesic classifications before using IVPCA. This study explored a new approach to analysing dynamic changes of postoperative analgesic consumptions.

Influence of intraoperative remifentanil and sufentanil on sensory perception: a randomized trial

OBJECTIVE

The clinical relevance of pro- and hyperalgesic effects of opioids is still a matter of debate. Particularly for remifentanil, an increased postoperative need for analgesics has been demonstrated suggesting opioid-induced hyperalgesia as a possible cause. The aim of the study was therefore to investigate the effect of intraoperatively applied remifentanil compared to sufentanil on somatosensory thresholds investigated with the quantitative sensory testing (QST) battery of the German Research Network on Neuropathic Pain (DFNS).

RESEARCH DESIGN AND METHODS

Twenty-three patients undergoing surgery of the female breast were randomly assigned to intraoperative remifentanil (0.4 μg × kg^-1 × min^-1) or sufentanil (0.25 μg × kg^-1 bolus, 0.15 μg × kg^-1, repetition after 60 min) application. Anesthesia was maintained BIS-guided (Bispectral index^TM) with propofol and postoperative analgesia was ensured with paracetamol (max. 3 g/24 h). Quantitative sensory testing was performed in the region of dermatome Th 5 in the mid-axillary line preoperatively and 20 h postoperatively.

CLINICAL TRIAL REGISTRATION

The study was registered at the German registry for clinical studies (DRKS00009002).

MAIN OUTCOME MEASURES

Comparison of somatosensory thresholds before versus after surgery and application of intraoperative remifentanil or sufentanil.

RESULTS

Sixteen patients could be finally included in the analysis. No differences of mechanical or thermal detection or pain thresholds were observed between pre- and postoperative testing or between remifentanil and sufentanil.

CONCLUSION

A change of somatosensory thresholds or a clinically relevant opioid-induced hyperalgesia in the selected small patient sample (segmental resections or mastectomy with or without sentinel lymph node biopsy, surgery length <90 minutes, sufficient postoperative pain medication with paracetamol due to rather low postoperative pain intensities) with remifentanil or sufentanil was not detected 20 h after surgery.

Influence of the Time of Intravenous Administration of Paracetamol on its Pharmacokinetics and Ocular Disposition in Rabbits

BACKGROUND AND OBJECTIVES

Paracetamol is one of the most common analgesics and antipyretics applied in health care. The aim of the study was to investigate the influence of the time-of-day administration on the paracetamol pharmacokinetics and its penetration into aqueous humour (AH).

METHODS

Rabbits were divided into three groups: I-receiving paracetamol at 08.00 h, II-receiving paracetamol at 16.00 h, and III-receiving paracetamol at 24.00 h. Paracetamol was administered intravenously at a single dose of 35 mg/kg. The concentrations of paracetamol and its metabolite (paracetamol glucuronide) in the plasma, as well as in AH were measured with the validated HPLC-UV method.

RESULTS

No significant differences in the pharmacokinetic parameters of paracetamol was observed. When the drug was administered at 24.00 h,  elimination half-life (t _1/2kel) of paracetamol glucuronide was longer than when the drug was administered 08.00 h (P = 0.0193). In addition, a statistically significant increase in the paracetamol glucuronide/paracetamol ratio was observed when the drug was administered at 08.00 vs. 16.00 h (P ≤ 0.0001) and 24.00 h (P ≤ 0.0001).

CONCLUSIONS

There was no chronobiological effect on the pharmacokinetic parameters of paracetamol.

Impact of chronobiology on neuropathic pain treatment

Inflammatory pain exhibits circadian rhythmicity. Recently, a distinct diurnal pattern has been described for peripheral neuropathic conditions. This diurnal variation has several implications: advancing understanding of chronobiology may facilitate identification of new and improved treatments; developing pain-contingent strategies that maximize treatment at times of the day associated with highest pain intensity may provide optimal pain relief as well as minimize treatment-related adverse effects (e.g., daytime cognitive dysfunction); and consideration of the impact of chronobiology on pain measurement may lead to improvements in analgesic study design that will maximize assay sensitivity of clinical trials. Recent and ongoing chronobiology studies are thus expected to advance knowledge and treatment of neuropathic pain.

Circadian variation of IV PCA use in patients after orthognathic surgery - a retrospective comparative study

Background

An understanding of the features of postoperative pain is essential for optimal analgesic dosing strategies. Using a visual analogue scale (VAS) score and patient controlled analgesia (PCA) infusion pattern analysis, an anesthesiologist can estimate when and how severely patients suffer from pain. Several reports have been published about circadian changes in the pain threshold. Postoperative pain was analyzed retrospectively in 250 patients who underwent orthognathic surgery.

Methods

A total of 250 patients were allocated into two groups according to the time of recovery from anesthesia. Patients in the early group (group E) recovered from anesthesia before 06:00 p.m. Patients in the late group (group L) recovered from anesthesia after 06:00 p.m. All patients received intravenous patient controlled analgesia (IV PCA) at the end of the operation. The VAS score of pain intensity was measured. Self-administration of bolus analgesic from the IV PCA device was also analyzed according to actual time and elapsed time.

Results

VAS scores showed no difference between the two groups except 36 hours after recovery from anesthesia. On POD1, there were two peaks for self-administration of bolus analgesics in group L and one peak in the morning for group E. Two peaks each in the morning and in the afternoon were shown in both groups on POD2.

Conclusions

Diurnal variance in pain should be considered for effective dosing strategies.

[Predictive factors and prevention of chronic postoperative pelvic and perineal pain]

INTRODUCTION

Chronic postoperative pain has been defined as pain arising after a surgical operation, present for at least 2 months, with no organic (active cancer or chronic infection) or preexisting cause. The purpose of this article is to review the risk factors and prevention of chronic postoperative pelvic and perineal pain.

MATERIAL AND METHODS

A review of the literature was performed by searching PubMed for articles on risk factors and prevention of chronic postoperative pelvic and perineal pain.

RESULTS

Chronic postoperative pain is frequent, disabling and represent a high cost to the community. This pain is generated by variable and complex interactions between the surgical procedure (the operated zone, perioperative management, the disease requiring the operative procedure) and the patient (age, gender, genetics, concomitant diseases, personal history). The multifactorial nature of chronic postoperative pain suggests the need for multidisciplinary management with prevention and reduction of the main risk factors. Similarly, appropriate management of acute postoperative pain has a major impact on the risk of chronic pain.

CONCLUSION

A good knowledge of the risk factors and appropriate prevention can decrease the incidence and consequences of chronic postoperative pain.

Circadian effects on neural blockade of intrathecal hyperbaric bupivacaine

Background

Circadian variations in the absorption, distribution, protein binding, elimination and metabolism of drugs account for many of the administration-time-dependent differences in their pharmacokinetics. The aim of this study is to determine whether the time of intrathecal injection influences spinal anesthesia.

Methods

Ninety patients scheduled for orthopedic surgery were randomly assigned to three groups. Each group received spinal anesthesia with 0.5% bupivacaine 10 mg at different times; group AM (8 am to 12:00), group Noon (12:00 to 4:00 pm) and group PM (4:00 pm to 8:00 pm). Sensory and motor blockade were assessed by pinprick and a four-point modified Bromage scale. Time to first postoperative analgesic requirement and side effects such as hypotension, bradycardia, nausea, and shivering were recorded.

Results

No significant differences were found among the three groups in peak sensory blockade, duration of motor block to Bromage 1 or side effects, but time to first postoperative analgesic requirement (P = 0.008), and recovery time of S1 sensation to pinprick were significantly prolonged in group Noon compared with the other groups (P = 0.03).

Conclusions

The tine of administration of spinal local anesthetics influences the duration of local anesthesia.

[Biological rhythms for anaesthesia and intensive care]

Knowledge of biological rhythms has led to better understanding of the time-of-day dependent effects of anaesthetic drugs. These chronopharmacological effects are currently explained by the biological rhythms modulating the pharmacokinetic, toxic and pharmacodynamic parameters of these substances. Such effect has been described for general anesthetics, local anaesthetics, analgesics as well as for antibiotics. But recent data also highlight that general anaesthetics, probably part of their brain effects, also alter the regulation of biological rhythms, including the sleep-wake or the endogenous circadian temperature rhythms. This desynchronization of biological rhythms can led to disturbance of the circadian secretion of many substances, including hormones. Finally, biological rhythms have been also described with regard to physiology of pain and cardiovascular physiopathology. The concept of biological rhythm should be present in mind not only for the clinical management of patients but also for setting studies in the field of anaesthesia, pain and intensive care.

Endogenous opiates and behavior: 2007

This paper is the thirtieth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2007 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.