A Systematic Review of Postoperative Pain Outcome Measurements Utilised in Regional Anesthesia Randomized Controlled Trials

Efficacy of different routes of acetaminophen administration for postoperative pain in children: a systematic review and network meta-analysis

PURPOSE

Acetaminophen is the most common drug used to treat acute pain in the pediatric population, given its wide safety margin, low cost, and multiple routes for administration. We sought to determine the most efficacious route of acetaminophen administration for postoperative acute pain relief in the pediatric surgical population.

METHODS

We conducted a systematic review of randomized controlled trials (RCTs) that included children aged between 30 days and 17 yr who underwent any type of surgical procedure and that evaluated the analgesic efficacy of different routes of administration of acetaminophen for the treatment of postoperative pain. We searched MEDLINE, CENTRAL, Embase, CINAHL, LILACs, and Google Scholar databases for trials published from inception to 16 April 2023. We assessed the risk of bias in the included studies using the Cochrane Risk of Bias 1.0 tool. We performed a frequentist network meta-analysis using a random-effects model. Our primary outcome was postoperative pain using validated pain scales.

RESULTS

We screened 2,344 studies and included 14 trials with 829 participants in the analysis. We conducted a network meta-analysis for the period from zero to two hours, including six trials with 496 participants. There was no evidence of differences between intravenous vs rectal routes of administration of acetaminophen (difference in means, -0.28; 95% confidence interval [CI], -0.62 to 0.06; very low certainty of the evidence) and intravenous vs oral acetaminophen (difference in means, -0.60; 95% CI, -1.20 to 0.01; low certainty of the evidence). For the comparison of oral vs rectal routes, we found evidence favouring the oral route (difference in means, -0.88; 95% CI, -1.44 to -0.31; low certainty of the evidence). Few trials reported secondary outcomes of interest; when comparing the oral and rectal routes in the incidence of nausea and vomiting, there was no evidence of differences (relative risk, 1.20; 95% CI, 0.81 to 1.78).

CONCLUSION

The available evidence on the effect of the administration route of acetaminophen on postoperative pain in children is very uncertain. The outcomes of postoperative pain control and postoperative vomiting may differ very little between the oral and rectal route. Better designed and executed RCTs are required to address this important clinical question.

STUDY REGISTRATION

PROSPERO (CRD42021286495); first submitted 19 November 2021.

fNIRS brain measures of ongoing nociception during surgical incisions under anesthesia

Significance: Functional near-infrared spectroscopy (fNIRS) has evaluated pain in awake and anesthetized states. Aim: We evaluated fNIRS signals under general anesthesia in patients undergoing knee surgery for anterior cruciate ligament repair. Approach: Patients were split into groups: those with regional nerve block (NB) and those without (non-NB). Continuous fNIRS measures came from three regions: the primary somatosensory cortex (S1), known to be involved in evaluation of nociception, the lateral prefrontal cortex (BA9), and the polar frontal cortex (BA10), both involved in higher cortical functions (such as cognition and emotion). Results: Our results show three significant differences in fNIRS signals to incision procedures between groups: (1) NB compared with non-NB was associated with a greater net positive hemodynamic response to pain procedures in S1; (2) dynamic correlation between the prefrontal cortex (PreFC) and S1 within 1 min of painful procedures are anticorrelated in NB while positively correlated in non-NB; and (3) hemodynamic measures of activation were similar at two separate time points during surgery (i.e., first and last incisions) in PreFC and S1 but showed significant differences in their overlap. Comparing pain levels immediately after surgery and during discharge from postoperative care revealed no significant differences in the pain levels between NB and non-NB. Conclusion: Our data suggest multiple pain events that occur during surgery using devised algorithms could potentially give a measure of "pain load." This may allow for evaluation of central sensitization (i.e., a heightened state of the nervous system where noxious and non-noxious stimuli is perceived as painful) to postoperative pain levels and the resulting analgesic consumption. This evaluation could potentially predict postsurgical chronic neuropathic pain.

Defining success in regional anaesthesia

Utilisation of regional anaesthesia is increasing globally; however, it remains challenging to determine the overall benefit of individual regional anaesthesia procedures. Like any peri-operative intervention, the benefit to the patient and healthcare system must outweigh any patient risk or resource implications. This review aims to identify markers of success in regional anaesthesia, categorise these into an objective framework and rationalise suggestions on how measuring outcomes in regional anaesthesia can be used to develop the widespread performance of this evolving subspecialty. This framework of measuring success of regional anaesthesia contains four pillars: patient-centred, population-centred, healthcare-centred and training-centred outcomes. Each pillar of success contains several outcomes which provide a structure for the measurement and development of regional anaesthesia success on a global scale.

Regional anaesthesia quality indicators for adult patients undergoing non-cardiac surgery: a systematic review

Improvement in healthcare delivery depends on the ability to measure outcomes that can direct changes in the system. An overview of quality indicators within the field of regional anaesthesia is lacking. This systematic review aims to synthesise available quality indicators, as per the Donabedian framework, and provide a concise overview of evidence-based quality indicators within regional anaesthesia. A systematic literature search was conducted using the databases MEDLINE, Embase, CINAHL and Cochrane from 2003 to present, and a prespecified search of regional anaesthesia society websites and healthcare quality agencies. The quality indicators relevant to regional anaesthesia were subdivided into peri-operative structure, process and outcome indicators as per the Donabedian framework. The methodological quality of the indicators was determined as per the Oxford Centre for Evidence-Based Medicine's framework. Twenty manuscripts met our inclusion criteria and, in total, 68 unique quality indicators were identified. There were 4 (6%) structure, 12 (18%) process and 52 (76%) outcome indicators. Most of the indicators were related to the safety (57%) and effectiveness (19%) of regional anaesthesia and were general in nature (60%). In addition, most indicators (84%) were based on low levels of evidence. Our study is an important first step towards describing quality indicators for the provision of regional anaesthesia. Future research should focus on the development of structure and process quality indicators and improving the methodological quality and usability of these indicators.

Pain assessment in clinical trials: a narrative review

Pain is a symptom measured in many clinical trials. For pain as an outcome domain, trialists need to choose adequate outcome measure(s), as there are myriad outcome measures for pain to choose from. To ensure consistency and uniformity in clinical trials and systematic reviews, core outcome sets (COS) have been defined; COS includes a predefined minimal list of core outcomes that should be measured within a trial, to ensure their consistency and comparability. COS is defined via consensus procedure, which includes relevant stakeholders such as experts from a specific field and patients. Along with outcomes, outcome measures for each outcome need to be defined to make sure that the outcomes will be measured consistently and uniformly. Hereby we reviewed studies that have examined use of recommended core outcome domains and outcome measures in clinical trials that would be expected to measure pain. Despite the existence of COS and defined core outcome measures (COMs), multiple studies have shown that these are not necessarily used in clinical trials, or in the relevant systematic reviews, which further increases heterogeneity of existing evidence, hinders evidence synthesis and trial comparability, and assessment of comparative effectiveness of interventions. Trialists are encouraged to use COS and COMs when designing clinical trials. Research community is encouraged to design interventions that will help with identifying barriers for using COS and COMs and interventions to foster their uptake. Use of consistent pain outcomes and pain outcome measures is in the interest of patients, research community, healthcare workers and decision-makers. For clinical conditions for which there are no COS and COMs, efforts to design them would be beneficial.

Is the minimal clinically important difference (MCID) in acute pain a good measure of analgesic efficacy in regional anesthesia?

In the field of acute pain medicine research, we believe there is an unmet need to incorporate patient related outcome measures that move beyond reporting pain scores and opioid consumption. The term “minimal clinically important difference” (MCID) defines the clinical benefit of an intervention as perceived by the patient, as opposed to a mathematically determined statistically significant difference that may not necessarily be clinically significant. The present article reviews the concept of MCID in acute postoperative pain research, addresses potential pitfalls in MCID determination and questions the clinical validity of extrapolating MCID determined from chronic pain and non-surgical pain studies to the acute postoperative pain setting. We further suggest the concepts of minimal clinically important improvement, substantial clinical benefit and patient acceptable symptom state should also represent aspirational outcomes for future research in acute postoperative pain management.

Perineural local anaesthetic catheter after major lower limb amputation trial (PLACEMENT): results from a randomised controlled feasibility trial

OBJECTIVES

To determine the feasibility of undertaking a randomised controlled effectiveness trial evaluating the use of a perineural catheter (PNC) after major lower limb amputation with postoperative pain as the primary outcome.

DESIGN

Randomised controlled feasibility trial.

SETTING

Two vascular Centres in South Wales, UK.

PARTICIPANTS

50 patients scheduled for major lower limb amputation (below or above knee) for complications of peripheral vascular disease.

INTERVENTIONS

The treatment arm received a PNC placed adjacent to the sciatic or tibial nerve at the time of surgery, with continuous infusion of levobupivacaine hydrochloride 0.125% for up to 5 days. The control arm received neither local anaesthetic nor PNC. Both arms received usual perioperative anaesthesia and postoperative analgesia.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcomes were the proportion of eligible patients who were randomised and the proportion of recruited patients who provided primary effectiveness outcome data. Secondary outcomes were: the proportion of recruited patients reaching 2 and 6 month follow-up and supplying pain data; identification of key cost drivers; development of an economic analysis framework for a future effectiveness trial; identification of barriers to recruitment and site set-up; and identification of the best way to measure postoperative pain.

RESULTS

Seventy-six of 103 screened patients were deemed eligible over a 10 month period. Fifty (64.5%) of these patients were randomised, with one excluded in the perioperative period. Forty-five (91.3%) of 49 recruited patients provided enough pain scores on a 4-point verbal rating scale to allow primary effectiveness outcome evaluation. Attrition rates were high; 18 patients supplied data at 6 month follow-up. Costs were dominated by length of hospital stay. Patients and healthcare professionals reported that trial processes were acceptable.

CONCLUSIONS

Recruitment of patients into a trial comparing PNC use to usual care after major lower limb amputation with postoperative pain measured on a 4-point verbal rating scale is feasible. Evaluation of longer-term symptoms is difficult.

TRIAL REGISTRATION NUMBER

ISRCTN: 85 710 690. EudraCT: 2016-003544-37.