Morten Sejer Hansen

Adverse effects of perioperative paracetamol, NSAIDs, glucocorticoids, gabapentinoids and their combinations: a topical review.

Post‐operative pain affects millions of patients worldwide and the post‐operative period has high rates of morbidity and mortality. Some of this morbidity may be related to analgesics. The aim of this review was to provide an update of current knowledge of adverse events (AE) associated with the most common perioperative non‐opioid analgesics: paracetamol, non‐steroidal anti‐inflammatory drugs (NSAIDs), glucocorticoids (GCCs), gabapentinoids and their combinations. The review is based on data from systematic reviews with meta‐analyses of analgesic efficacy and/or adverse effects of perioperative non‐opioid analgesics, and randomised trials and cohort/retrospective studies. Generally, data on AE are sparse and related to the immediate post‐operative period. For paracetamol, the incidence of AEs appears trivial. Data are inconclusive regarding an association of NSAIDs with mortality, cardiovascular events, surgical bleeding and renal impairment. Anastomotic leakage may be associated with NSAID usage. No firm evidence exists for an association of NSAIDs with impaired bone healing. Single‐dose GCCs were not significantly related to increased infection rates or delayed wound healing. Gabapentinoid treatment was associated with increased sedation, dizziness and visual disturbances, but the clinical relevance needs clarification. Importantly, data on AEs of combinations of the above analgesics are sparse and inconclusive. Despite the potential adverse events associated with the most commonly applied non‐opioid analgesics, including their combinations, reporting of such events is sparse and confined to the immediate perioperative period. Knowledge of benefit and harm related to multimodal pain treatment is deficient and needs clarification in large trials with prolonged observation.

Pain treatment after craniotomy: where is the (procedure- specific) evidence? A qualitative systematic review

Context and objective Pain following craniotomy has been demonstrated to be frequent and moderate-to-severe in nature. In recent years, the focus on the challenges in treatment of postoperative pain following craniotomy has increased. Fear of using opioids because of their wide array of side-effects has led to the search for alternative analgesic options. The objective of this systematic review was to evaluate current evidence about analgesic therapy following craniotomy. Data sources PubMed database, Embase, Cochrane library, Google scholar and the Cumulative Index to Nursing and Allied Health Literature. Eligibility criteria Randomised double-blinded placebo-controlled trials (RCTs) with pain or supplemental postoperative analgesic consumption as an endpoint were included in the analysis. Results A total of 34 RCTs were identified, and nine RCTs were included in the final analysis, with a total of 519 patients (251 control vs. 268 active treatment). Four treatment modalities – scalp infiltration (five RCTs), nerve scalp block (two RCTs), parecoxib (one RCT) and patient-controlled analgesia with morphine (one RCT) – were evaluated. Scalp infiltration with local anaesthetic may provide adequate analgesia in the first few postoperative hours, and nerve scalp block may provide longer lasting analgesia for about 6 h. Morphine was found to reduce total analgesic rescue doses with no significant effect on nausea and no other side-effects. No significant evidence was found to support the use of parecoxib in the treatment of postcraniotomy pain. Conclusion No firm recommendations on analgesic therapy following craniotomy can be given because the number of well performed RCTs is limited and the study populations are very small. However, evidence on scalp infiltration suggests an analgesic effect in the first few postoperative hours. There is an urgent need for well performed RCTs on pain therapy following craniotomy.

Intranasal fentanyl in the treatment of acute pain--a systematic review.

Due to its non‐invasive mode of administration, intranasal (IN) application of drugs may be a valuable alternative to non‐invasive pain management. With characteristics that appear to be ideal for IN application, IN fentanyl may have a place in the out‐of‐hospital treatment and the paediatric population. The objective of this systematic review was to evaluate the current evidence of IN fentanyl in the treatment of acute pain. Reports of randomized controlled trials (RCTs) of IN fentanyl in treatment of pain were systematically sought using the PubMed database, Embase, Google scholar, Cochrane database, and Cumulative Index to Nursing and Allied Health Literature. Reports were considered for inclusion if they were double‐blinded randomized controlled trials (RCTs) of IN fentanyl in the treatment of acute pain. Thirty‐two RCTs were identified, and 16 were included in the final analysis. No significant analgesic differences between IN fentanyl and intravenous (IV) fentanyl were demonstrated in treatment of acute and post‐operative pain. Significant analgesic effect of IN fentanyl was demonstrated in the treatment of breakthrough pain in cancer patients. In the paediatric population, results demonstrated some analgesic effect of IN fentanyl following myringotomy, no analgesic effect following voiding cystourethrography, and finally, no significant analgesic difference after long bone fractures, in burns patients, and in post‐operative pain relief when compared to IV morphine, oral morphine, or IV fentanyl, respectively. Significant analgesic effect of IN fentanyl was demonstrated in the treatment of breakthrough pain in cancer patients. However, the significant deficiencies in trials investigating acute and post‐operative pain, and the paediatric population makes firm recommendations impossible.

Gabapentin for post-operative pain management – a systematic review with meta-analyses and trial sequential analyses

Perioperative pain treatment often consist of combinations of non‐opioid and opioid analgesics, ‘multimodal analgesia’, in which gabapentin is currently used. The aim was to document beneficial and harmful effects of perioperative gabapentin treatment.

The analgesic effect of wound infiltration with local anaesthetics after breast surgery: a qualitative systematic review.

Wound infiltration with local anaesthetics is commonly used during breast surgery in an attempt to reduce post‐operative pain and opioid consumption. The aim of this review was to evaluate the effect of wound infiltration with local anaesthetics compared with a control group on post‐operative pain after breast surgery.

Postoperative pain treatment after total knee arthroplasty: A systematic review

Introduction The aim of this systematic review was to document efficacy, safety and quality of evidence of analgesic interventions after total knee arthroplasty (TKA). Methods This PRISMA-compliant and PROSPERO-registered review includes all-language randomized controlled trials of medication-based analgesic interventions after TKA. Bias was evaluated according to Cochrane methodology. Outcomes were opioid consumption (primary), pain scores at rest and during mobilization, adverse events, and length of stay. Interventions investigated in three or more trials were meta-analysed. Outcomes were evaluated using forest plots, Grading of Recommendations Assessment, Development and Evaluation (GRADE), L’Abbe Plots and trial sequential analysis. Results The included 113 trials, investigating 37 different analgesic interventions, were characterized by unclear/high risk of bias, low assay sensitivity and considerable differences in pain assessment tools, basic analgesic regimens, and reporting of adverse events. In meta-analyses single and continuous femoral nerve block (FNB), intrathecal morphine, local infiltration analgesia, intraarticular injection of local anaesthetics, non-steroidal anti-inflammatory drugs, and gabapentinoids demonstrated significant analgesic effects. The 24-hour morphine-sparing effects ranged from 4.2 mg (CI: 1.3, 7.2; intraarticular local anaesthetics), to 16.6 mg (CI: 11.2, 22; single FNB). Pain relieving effects at rest at 6 hours ranged from 4 mm (CI: -10, 2; gabapentinoids), to 19 mm (CI: 8, 31; single FNB), and at 24 hours from 3 mm (CI: -2, 8; gabapentinoids), to 16 mm (CI: 8, 23; continuous FNB). GRADE-rated quality of evidence was generally low. Conclusion A low quality of evidence, small sample sizes and heterogeneity of trial designs prohibit designation of an optimal procedure-specific analgesic regimen after TKA.

Post‐operative serious adverse events in a mixed surgical population – a retrospective register study

The number of surgical procedures is increasing, and knowledge of surgical risk factors, post‐operative mortality and serious adverse events (SAE) is essential. The aim with our study was to determine the risk of a composite outcome of post‐operative: death; myocardial infarction; pulmonary embolism; stroke; gastrointestinal bleeding; dialysis or reoperation.

The Area of Secondary Hyperalgesia following Heat Stimulation in Healthy Male Volunteers: Inter- and Intra-Individual Variance and Reproducibility

Introduction Clinical pain models can be applied when investigating basic physiologic pain responses in healthy volunteers. Several pain models exist; however, only few have been adequately validated. Our primary aim with this prospective study was to investigate the intra- and inter-individual variation in secondary hyperalgesia elicited by brief thermal sensitization (45°C for 3 min) in healthy volunteers. Material and Methods Fifty healthy volunteers were included. Areas of secondary hyperalgesia following brief thermal sensitization were investigated by 2 observers on 4 experimental days, with a minimum interval of 7 days. Additionally, heat pain detection threshold and pain during thermal stimulation (45°C for 1 min.), and the psychological tests Pain Catastrophizing Scale and Hospital Anxiety and Depression Score were applied. Results For areas of secondary hyperalgesia, an intra-observer intra-person correlation of 0.85, 95% CI [0.78, 0.90], an intra-observer inter-person correlation of 0.03, 95% CI [0.00, 0.16], and a coefficient of variation of 0.17, 95% CI [0.14, 0.21] was demonstrated. Four percent of the study population had areas of secondary hyperalgesia both below the 1st and above the 3rd quartile considering all included participants. Heat pain detection threshold predicted area of secondary hyperalgesia with an adjusted R2 of 0.20 (P = 0.0006). Conclusions We have demonstrated a low intra-individual, and a high inter-individual variation in thermally induced secondary hyperalgesia. We conclude that brief thermal sensitization produce secondary hyperalgesia with a high level of reproducibility, which can be applied to investigate different phenotypes related to secondary hyperalgesia in healthy volunteers. Trial Registration clinicaltrials.gov NCT02166164

Heat pain detection threshold is associated with the area of secondary hyperalgesia following brief thermal sensitization: a study of healthy male volunteers

Introduction The area of secondary hyperalgesia following brief thermal sensitization (BTS) of the skin and heat pain detection thresholds (HPDT) may both have predictive abilities in regards to pain sensitivity and clinical pain states. The association between HPDT and secondary hyperalgesia, however, remains unsettled, and the dissimilarities in physiologic properties suggest that they may represent 2 distinctively different pain entities. The aim of this study was to investigate the association between HPDT and BTS-induced secondary hyperalgesia. Methods A sample of 121 healthy male participants was included and tested on 2 separate study days with BTS (45°C, 3 minutes), HPDT, and pain during thermal stimulation (45°C, 1 minute). Areas of secondary hyperalgesia were quantified after monofilament pinprick stimulation. The pain catastrophizing scale (PCS) and hospital anxiety and depression scale (HADS) were also applied. Results A significant association between HPDT and the size of the area of secondary hyperalgesia (p<0.0001) was found. The expected change in area of secondary hyperalgesia due to a 1-degree increase in HPDT was estimated to be −27.38 cm2, 95% confidence interval (CI) of −37.77 to −16.98 cm2, with an R2 of 0.19. Likewise, a significant association between HADS-depression subscore and area of secondary hyperalgesia (p=0.046) was found, with an estimated expected change in secondary hyperalgesia to a 1-point increase in HADS-depression subscore of 11 cm2, 95% CI (0.19–21.82), and with R2 of 0.03. We found no significant associations between secondary hyperalgesia area and PCS score or pain during thermal stimulation. Conclusion HPDT and the area of secondary hyperalgesia after BTS are significantly associated; however, with an R2 of only 19%, HPDT only offers a modest explanation of the inter-participant variation in the size of the secondary hyperalgesia area elicited by BTS.

The association between areas of secondary hyperalgesia and volumes of the caudate nuclei and other pain relevant brain structures—A 3-tesla MRI study of healthy men

Introduction Central sensitization plays a pivotal role in maintenance of pain and is believed to be intricately involved in several chronic pain conditions. One clinical manifestation of central sensitization is secondary hyperalgesia. The degree of secondary hyperalgesia presumably reflects individual levels of central sensitization. The objective of this study was to investigate the association between areas of secondary hyperalgesia and volumes of the caudate nuclei and other brain structures involved in pain processing. Materials and methods We recruited 121 healthy male participants; 118 were included in the final analysis. All participants underwent whole brain magnetic resonance imaging (MRI). Prior to MRI, all participants underwent pain testing. Secondary hyperalgesia was induced by brief thermal sensitization. Additionally, we recorded heat pain detection thresholds (HPDT), pain during one minute thermal stimulation (p-TS) and results of the Pain Catastrophizing Scale (PCS) and Hospital Anxiety and Depression score (HADS). Results We found no significant associations between the size of the area of secondary hyperalgesia and the volume of the caudate nuclei or of the following structures: primary somatosensory cortex, anterior and mid cingulate cortex, putamen, nucleus accumbens, globus pallidus, insula and the cerebellum. Likewise, we found no significant associations between the volume of the caudate nuclei and HPDTs, p-TS, PCS and HADS. Conclusions Our findings indicate that the size of the secondary hyperalgesia area is not associated with the volume of brain structures relevant for pain processing, suggesting that the propensity to develop central sensitization, assessed as secondary hyperalgesia, is not correlated to brain structure volume.