Phenotype- and species-specific skin proteomic signatures for incision-induced pain in humans and mice.

BACKGROUND: Acute pain after surgery is common and often leads to chronic post-surgical pain, but neither treatment nor prevention is currently sufficient. We hypothesised that specific protein networks (protein-protein interactions) are relevant for pain after surgery in humans and mice. METHODS: Standardised surgical incisions were performed in male human volunteers and male mice. Quantitative and qualitative sensory phenotyping were combined with unbiased quantitative mass spectrometry-based proteomics and protein network theory. The primary outcomes were skin protein signature changes in humans and phenotype-specific protein-protein interaction analysis 24 h after incision. Secondary outcomes were interspecies comparison of protein regulation as well as protein-protein interactions after incision and validation of selected proteins in human skin by immunofluorescence. RESULTS: Skin biopsies in 21 human volunteers revealed 119/1569 regulated proteins 24 h after incision. Protein-protein interaction analysis delineated remarkable differences between subjects with small (low responders, n=12) and large incision-related hyperalgesic areas (high responders, n=7), a phenotype most predictive of developing chronic post-surgical pain. Whereas low responders predominantly showed an anti-inflammatory protein signature, high responders exhibited signatures associated with a distinct proteolytic environment and persistent inflammation. Compared to humans, skin biopsies in mice habored even more regulated proteins (435/1871) 24 h after incision with limited overlap between species as assessed by proteome dynamics and PPI. Immunohistochemistry confirmed the expression of high priority candidates in human skin biopsies. CONCLUSIONS: Proteome profiling of human skin after incision revealed protein-protein interactions correlated with pain and hyperalgesia, which may be of potential significance for preventing chronic post-surgical pain. Importantly, protein-protein interactions were differentially modulated in mice compared to humans opening new avenues for successful translational research.

Chronic Pain Following Fracture-Related Surgery: Posttraumatic Rather Than Postsurgical Origin Promotes Chronification-A Prospective Observational Study With 1-Year Follow-up.

BACKGROUND: Chronic posttraumatic/postsurgical pain (CPSP) is common after traumatic or surgical damage. Exposure to both trauma and surgery, with the potential for repeated bone and nerve damage, may increase the risk of CPSP after fracture-related surgery. But the (long-term) incidences of CPSP and neuropathic CPSP and the ensuing burdens are unknown. Therefore, the patients were prospectively assessed within 1 year, and the patient-specific characteristics were explored. METHODS: Between 2017 and 2018, 127 patients (age: 52.9 ± 17.1 years, male: 55.1%) with traumatic fractures needing osteosynthesis (extremities: 91.3%) were assessed posttrauma (before surgery), postsurgery at days 1 to 5, 6 weeks, 3 and 12 months. The primary outcomes are as follows: incidence at 3 and 12 months of CPSP (defined as pain intensity on a numerical rating scale [NRS: 0-10] ≥3), secondary exploration: neuropathic CPSP (NRS ≥3 and Douleur Neuropathique 4 interview [DN4i] score ≥3 [Douleur Neuropathique interview: 0-7]); burden: quality of life (QoL, the EuroQOL five dimensions questionnaire [EQ-5D-3L] descriptive system); and inter alia, the number of analgesics (trial registration: DRKS00011601). RESULTS: The incidence of CPSP was 57.1% (52/91, n/N) at 3 and 42.7% (35/82) at 12 months postsurgery, including neuropathic CPSP 7.7% (4/52) and 17.1% (6/35), respectively. Descriptively, posttraumatic higher pain intensity at rest (difference of 0.9 ± 1.8 NRS) and the need for more frequent analgesics (by 34.3%) were associated with CPSP a year after surgery compared to those without. As soon as week 6, these patients had developed descriptively a 15% more impaired QoL, with 25% more impairment after 1 year. The patients with CPSP presented with at least 1 neuropathic symptom 12 months later in 68.6% (24/35) of cases, mainly with an early posttraumatic occurrence (without fulfilling the definition of neuropathic CPSP). CONCLUSIONS: After early fracture-related surgery, high incidences of CPSP (43%) were prospectively observed 1 year postsurgery, up to approximately 1 in 5 patients who had neuropathic CPSP. At the same time, CPSP was accompanied with an impacted QoL and analgesic dependence, both indicating clinical relevance. Moreover, the high incidence and the early posttraumatic occurrence of more intense pain suggest that the initial fracture-related trauma, rather than the surgical trauma, may predominantly trigger CPSP at Y1 (1 year). Therefore, these exploratory results set the direction of required future research. A future clinical hypothesis might be: treat first what hurts first.

Incidence, Time Course and Influence on Quality of Life of Intensive Care Unit-Acquired Weakness Symptoms in Long-Term Intensive Care Survivors.

PURPOSE: Intensive care unit-acquired weakness (ICUAW) can manifest as muscle weakness or neuropathy-like symptoms, with diagnosis remaining a challenge. Uncertainties surround the long-term cause and sequelae. Therefore, the purpose was to assess incidence, time course and long-term influence on quality of life (QoL) of symptoms in ICU survivors. METHODS: After ethical approval and registration (www.drks.de: DRKS00011593), in a single-center cohort study all patients admitted to the ICU in 2007-2017 in a German university hospital were screened. Out of 1,860 patients (≥7d ICU care including ventilation support for ≥72 h, at least 6mo-10y after ICU) 636 were deceased, 912 survivors were contacted. RESULTS: 149 former patients (age: 63.5 ± 13.1y; males: 73%; duration in ICU: 20.8 ± 15.7d; duration of ventilation: 16.5 ± 13.7 h; time post-ICU: 4.4 ± 2.7y, 5-10y: 43%) consented to be interviewed concerning occurrence, duration, recovery and consequences of ICUAW-associated muscle weakness or neuropathy-like symptoms after ICU. In 75% at least 1 persistent or previous symmetrical symptom was reported (myopathy-like muscle weakness: 43%; neuropathy-like symptoms: 13%; both: 44%) and rated as incidence of ICUAW. However, only 18% of participants had received an ICUAW diagnosis by their physicians, although 62% had persistent symptoms up to 10y after ICU (5-10y: 46%). Only 37% of participants reported a complete recovery of symptoms, significantly associated with an initially low number of symptoms after ICU (p < 0.0001), myopathy-like symptoms (p = 0.024), and younger age at the time of ICU admission (55.7 ± 13.1 vs. 62.6 ± 10.6y, p < 0.001). ICUAW still impaired the QoL at the time of the interview in 74% of affected survivors, with 30% reporting severe impairment. CONCLUSION: ICUAW symptoms were disturbingly common in the majority of long-term survivors, indicating that symptoms persist up to 10y and frequently impair QoL. However, only a small number of patients had been diagnosed with ICUAW. Trial registry: Deutsches Register Klinischer Studien (DRKS), https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00011593, registration number: DRKS00011593.

Pectoral nerve blocks for breast surgery: A meta-analysis.

BACKGROUND: Pectoral nerve blocks (PECS block) might be an interesting new regional anaesthetic technique in patients undergoing breast surgery. OBJECTIVE: The aim of this meta-analysis was to investigate postoperative pain outcomes and adverse events of a PECS block compared with no treatment, sham treatment or other regional anaesthetic techniques in women undergoing breast surgery. DESIGN: We performed a systematic review of randomised controlled trials (RCT) with meta-analysis and risk of bias assessment. DATA SOURCES: The databases MEDLINE, CENTRAL (until December 2019) and clinicaltrials.gov were systematically searched. ELIGIBILITY CRITERIA: All RCTs investigating the efficacy and adverse events of PECS compared with sham treatment, no treatment or other regional anaesthetic techniques in women undergoing breast surgery with general anaesthesia were included. RESULTS: A total of 24 RCTs (1565 patients) were included. PECS (compared with no treatment) block might reduce pain at rest [mean difference -1.14, 95% confidence interval (CI), -2.1 to -0.18, moderate quality evidence] but we are uncertain regarding the effect on pain during movement at 24 h after surgery (mean difference -1.79, 95% CI, -3.5 to -0.08, very low-quality evidence). We are also uncertain about the effect of PECS block on pain at rest at 24 h compared with sham block (mean difference -0.83, 95% CI, -1.80 to 0.14) or compared with paravertebral block (PVB) (mean difference -0.18, 95% CI, -1.0 to 0.65), both with very low-quality evidence. PECS block may have no effect on pain on movement at 24 h after surgery compared with PVB block (mean difference -0.56, 95% CI, -1.53 to 0.41, low-quality evidence). Block-related complications were generally poorly reported. CONCLUSION: There is moderate quality evidence that PECS block compared with no treatment reduces postoperative pain intensity at rest. The observed results were less pronounced if patients received a sham block. Furthermore, PECS blocks might be equally effective as PVBs. Due to mostly low-quality or very low-quality evidence level, further research is warranted. PROTOCOL REGISTRATION: CRD42019126733.

The posterior femoral cutaneous nerve contributes significantly to sensory innervation of the lower leg: an anatomical investigation.

BACKGROUND: Incomplete peripheral nerve blocks distal to the popliteal region are commonly considered a sciatic and femoral/saphenous nerve block failure. The existence of a much more distal innervation area of the posterior femoral cutaneous nerve (PFCN) as described has not been assumed yet. We therefore investigated the distal termination of the PFCN in the lower leg. METHODS: In 83 human lower extremities embalmed with Theil's method, the course of the PFCN was investigated from the sub-gluteal fold to the most distal macroscopically dissectible branch. The topographic connection to other landmarks, such as the small saphenous vein or small arteries, was investigated. RESULTS: Popliteal ending of the PFCN was found in 9.7% of cases. The PFCN terminated at the proximal or distal lower leg in 45.7% and 44.6% of cases, respectively. The PFCN had a close connection to the Achilles tendon in 13.2% of cases and was found distally to the medial malleolus in one case. The small saphenous vein was close to the PFCN in 90.3% of cases and can therefore be used as a landmark to identify the nerve. In 40.9% of cases, the PFCN was accompanied by a small descending branch of the inferior gluteal artery. In two cases, an innervation of the fibula or calcaneus periosteum was found. CONCLUSIONS: The PFCN has a much more distal termination in the lower leg than previously demonstrated. To ensure complete anaesthesia of the lower leg and foot, the PFCN must be included in combined peripheral nerve block procedures.

Does simulation-based training in medical education need additional stressors? An experimental study.

The increased curricular integration of simulation-based training (SBT) in medical education is accompanied by researchers' calls to examine the effectiveness of SBT. We address conflicting results regarding effects of an added stressor on learning outcomes. In an experimental setting, one group of medical students (N = 20) performed cardiopulmonary resuscitation on a patient simulator. For a second group (N = 21) the scenario differed in that they encountered a defect defibrillator. We found participants of both groups to show increased biological stress-levels, independent of group allocation. Paradoxically, participants who encountered the equipment failure subjectively reported less stress. We discuss the implications of the comparable high stress levels in both groups with regards to future studies. We further discuss the result regarding subjective stress levels within the framework of attribution theory. Practitioner summary: The results of our experimental study underline the need for evidence-based choices of additional stressors for the design of simulation scenarios. We describe the choice of stimuli and setting in detail to maximise practical value for the construction of simulation-based medical trainings.

Adductor canal blocks for postoperative pain treatment in adults undergoing knee surgery.

BACKGROUND: Peripheral regional anaesthesia techniques are well established for postoperative pain treatment following knee surgery. The adductor canal block (ACB) is a new technique, which can be applied as a single shot or by catheter for continuous regional analgesia. OBJECTIVES: To compare the analgesic efficacy and adverse events of ACB versus other regional analgesic techniques or systemic analgesic treatment for adults undergoing knee surgery. SEARCH METHODS: We searched CENTRAL, MEDLINE, and Embase, five other databases, and one trial register on 19 September 2018; we checked references, searched citations, and contacted study authors to identify additional studies. SELECTION CRITERIA: We included all randomized controlled trials (RCTs) comparing single or continuous ACB versus other regional analgesic techniques or systemic analgesic treatment. Inclusion was independent of the technique used (landmarks, peripheral nerve stimulator, or ultrasound) and the level of training of providers. DATA COLLECTION AND ANALYSIS: We used Cochrane's standard methodological procedures. Our primary outcomes were pain intensity at rest and during movement; rate of accidental falls; and rates of opioid-related adverse events. We used GRADE to assess the quality of evidence for primary outcomes. MAIN RESULTS: We included 25 RCTs (1688 participants) in this review (23 trials combined within meta-analyses). In 18 studies, participants underwent total knee arthroplasty (TKA), whereas seven trials investigated patients undergoing arthroscopic knee surgery. We identified 11 studies awaiting classification and 11 ongoing studies. We investigated the following comparisons. ACB versus sham treatment We included eight trials for this comparison. We found no significant differences in postoperative pain intensity at rest (2 hours: standardized mean difference (SMD) -0.56, 95% confidence interval (CI) -1.20 to 0.07, 4 trials, 208 participants, low-quality evidence; 24 hours: SMD -0.49, 95% CI -1.05 to 0.07, 6 trials, 272 participants, low-quality evidence) or during movement (2 hours: SMD -0.59, 95% CI -1.5 to 0.33; 3 trials, 160 participants, very low-quality evidence; 24 hours: SMD 0.03, 95% CI -0.26 to 0.32, 4 trials, 184 participants, low-quality evidence). Furthermore, they noted no evidence of a difference in postoperative nausea between groups (24 hours: risk ratio (RR) 1.91, 95% CI 0.48 to 7.58, 3 trials, 121 participants, low-quality evidence). One trial reported that no accidental falls occurred 24 hours postoperatively (low-quality evidence). ACB versus femoral nerve block We included 15 RCTs for this comparison. We found no evidence of a difference in postoperative pain intensity at rest (2 hours: SMD -0.74, 95% CI -1.76 to 0.28, 5 trials, 298 participants, low-quality evidence; 24 hours: SMD 0.04, 95% CI -0.09 to 0.18, 12 trials, 868 participants, high-quality evidence) or during movement (2 hours: SMD -0.47, 95% CI -1.86 to 0.93, 2 trials, 88 participants, very low-quality evidence; 24 hours: SMD 0.56, 95% CI -0.00 to 1.12, 9 trials, 576 participants, very low-quality evidence). They noted no evidence of a difference in postoperative nausea (24 hours: RR 1.22, 95% CI 0.42 to 3.54, 2 trials, 138 participants, low-quality evidence) and no evidence that the rate of accidental falls during postoperative care was significantly different between groups (24 hours: RR 0.20, 95% CI 0.04 to 1.15, 3 trials, 172 participants, low-quality evidence). AUTHORS' CONCLUSIONS: We are currently uncertain whether patients treated with ACB suffer from lower pain intensity at rest and during movement, fewer opioid-related adverse events, and fewer accidental falls during postoperative care compared to patients receiving sham treatment. The same holds true for the comparison of ACB versus femoral nerve block focusing on postoperative pain intensity. The overall evidence level was mostly low or very low, so further research might change the conclusion. The 11 studies awaiting classification and the 11 ongoing studies, once assessed, may alter the conclusions of this review.

Relevance of peripheral cholinesterase activity on postoperative delirium in adult surgical patients (CESARO): A prospective observational cohort study.

BACKGROUND: The cholinergic system is considered to play a key role in the development of postoperative delirium (POD), which is a common complication after surgery. OBJECTIVES: To determine whether peri-operative acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activities are associated with the development of POD in in-hospital surgical patients, and raise hypotheses on cholinergic regulatory mechanisms in POD. DESIGN: A prospective multicentre observational study by the Peripheral Cholinesterase-activity on Neurocognitive Dysfunctions in Surgical Patients (CESARO) study group. SETTING: Nine German hospitals. PATIENTS: Patients of at least 18 years of age scheduled for inpatient elective surgery for a variety of surgical procedures. A total of 650 patients (mean age 61.5 years, 52.8% male) were included. METHODS: Clinical variables, and peripheral AChE and BuChE activities, were assessed throughout the peri-operative period using bedside point-of-care measurements (one pre-operative and two postoperative measurements). POD screening was conducted postoperatively for at least 24 h and up to the third postoperative day using a validated screening tool (nursing delirium screening scale). RESULTS: In all, 179 patients (27.5%) developed POD within the early postoperative phase. There was a lower BuChE activity in patients with delirium compared with patients without delirium pre-operatively (Cohen's r = 0.07, P = 0.091), on postoperative day 1 (Cohen's r = 0.12, P = 0.003) and on postoperative day 2 (Cohen's r = 0.12, P = 0.002). In contrast, there was a significantly higher AChE activity in patients with delirium compared with patients without delirium pre-operatively (Cohen's r = 0.10, P = 0.012), on postoperative day 1 (Cohen's r = 0.11, P = 0.004) and on postoperative day 2 (Cohen's r = 0.13, P = 0.002). After adjusting for covariates in multiple logistic regression, a significant association between both BuChE and AChE activities and POD was not found. However, in the multivariable analysis using the Generalized Estimating Equation, cholinesterase activities showed that a decrease of BuChE activity by 100 U L increased the risk of a delirium by approximately 2.1% (95% CI 1.6 to 2.8%) and for each 1 U g of haemoglobin increase in AChE activity, there was a 1.4% (95% CI 0.6 to 2.2%) increased risk of POD. CONCLUSION: Peri-operative peripheral cholinesterase activities may be related to the development of POD, but the clinical implications remain unclear. Further studies, in homogeneous patient groups with a strict protocol for measurement time points, are needed to investigate the relationship between cholinesterase activities and POD. TRIAL REGISTRATION: www.clinicaltrials.gov. Identifier NCT01964274.

Correction to: Inhalative sedation with small tidal volumes under venovenous ECMO.

In the original publication, the affiliations of fourth and fifth authors were published incorrectly. The corrected affiliations are given in this correction.

Inhalative sedation with small tidal volumes under venovenous ECMO.

BACKGROUND: Inhalative sedation is an emerging method for long-term sedation in intensive care therapy. There is evidence that it is easy to control and may be beneficial compared to intravenous sedation. Yet little is known about the use in patients with compromised lung function. In this retrospective analysis, we searched files of patients receiving inhalative sedation under venovenous extracorporeal membrane oxygenator (vv-ECMO) support due to lung failure. METHODS: After ethical approval, we performed a retrospective analysis of patients receiving vv-ECMO support and inhalative sedation in the surgical ICU in 2015. Isoflurane was administered via the AnaConDa®-system. Sedation was tested using Richmond Agitation and Sedation scale (RASS). RESULTS: 7 patients were identified. Median age was 50 years (26/70 years). All were male. Median ECMO runtime was 129 h (37/1008 h) and the survival rate was 57.9%. Dose of isoflurane was 1.7 ml/h (0.8 / 4.0 ml/h) resulting in expiratory concentrations of 0.8 Vol% (0.3/1.8 Vol%), inspiratory of 0.6 Vol% (0.1/1.4 Vol%). Higher concentrations of isoflurane were associated with increased depth of sedation (expiratory p = 0.016; inspiratory p = 0.027; averaged p = 0.015). With tidal volume below 350 ml, association was still present for expiratory and averaged concentrations of isoflurane (expiratory p = 0.031; inspiratory p = 0.082; average p = 0.039). CONCLUSIONS: This is the first study that shows that inhalative concentrations of isoflurane are associated with depth of sedation in patients with lung failure. We were able to show that even with major impacts in lung mechanics and function targeted sedation with volatile anaesthetics is feasible and dose-response relationship appears to exist.

Efficacy and safety of dexmedetomidine in peripheral nerve blocks: A meta-analysis and trial sequential analysis.

BACKGROUND: The duration of analgesia provided by nerve blocks is limited if local anaesthetics are administered alone. Therefore, several additives, including dexmedetomidine (DEX), have been investigated in order to prolong postoperative analgesia following single-shot regional anaesthesia. OBJECTIVES: The aim of this meta-analysis was to assess the efficacy and safety of the addition of perineural DEX to local anaesthetics compared with local anaesthetics alone or local anaesthetics combined with systemic administration of DEX. DESIGN: A systematic review of randomised controlled trials (RCT) with meta-analysis, trial sequential analysis and assessment of the quality of evidence by the GRADE approach. DATA SOURCES: The databases MEDLINE, CENTRAL and EMBASE (to May 2017) were systematically searched. ELIGIBILITY CRITERIA: All RCTs investigating the efficacy and safety of perineural DEX combined with local anaesthetics compared with local anaesthetics alone or local anaesthetics in combination with systemic DEX in peripheral nerve blocks of adults undergoing surgery were included. RESULTS: A total of 46 RCTs (3149 patients) were included. Patients receiving perineural DEX combined with local anaesthetics had a longer duration of analgesia than local anaesthetics alone [mean difference 4.87 h; 95% confidence interval (95% CI) 4.02 to 5.73; P < 0.001; I = 100%; moderate-quality evidence]. The most important adverse events in the DEX group were intraoperative bradycardia [risk ratio 2.83; 95% CI 1.50 to 5.33; P = 0.035; I = 40%; very low-quality evidence] and hypotension (risk ratio 3.42; 95% CI 1.24 to 9.48; P = 0.002; I = 65%; very low quality evidence). In contrast, there were no differences in the duration of analgesia between perineural or intravenous DEX combined with local anaesthetics (mean difference 0.98 h; 95% CI -0.12 to 2.08; P = 0.08; I = 0%). CONCLUSION: This meta-analysis demonstrated that DEX in combination with local anaesthetics increases postoperative analgesia for around 5 h. However, there are higher risks of intraoperative hypotension and bradycardia. Findings on side effects are associated with high uncertainty. Initial evidence suggests no difference in the duration of analgesia associated with systemic or perineural DEX. TRIAL REGISTRATION: CRD42016042486.

Efficacy and safety of buprenorphine in peripheral nerve blocks: A meta-analysis of randomised controlled trials.

BACKGROUND: The duration of analgesia provided by nerve blocks is limited if local anaesthetics are administered alone. Therefore, a variety of additives to local anaesthetics have been investigated to prolong postoperative analgesia following single-shot nerve blocks. OBJECTIVE(S): The aims of the current meta-analysis were to assess the efficacy and safety of the addition of perineural buprenorphine to local anaesthetic compared with local anaesthetic alone, or combined with systemic administration of buprenorphine, or other perineural opioids for peripheral nerve blocks. DESIGN: Systematic review and meta-analysis of randomised controlled trials (RCTs). DATA SOURCES: The following data sources were systematically searched: MEDLINE, CENTRAL and EMBASE (till 03/2016). ELIGIBILITY CRITERIA: All RCTs focusing on the efficacy and safety of perineural buprenorphine combined with local anaesthetic compared with local anaesthetic alone, or in combination with systemic buprenorphine, or other perineural opioids for peripheral nerve blocks were included. RESULTS: We included 13 RCTs (685 patients). Participants treated with perineural buprenorphine combined with local anaesthetic showed a longer duration of analgesia compared with those receiving local anaesthetic alone [mean difference 8.64 h, 95% confidence interval (CI) (6.44 to 10.85); P < 0.01]. However, the buprenorphine group had a significantly higher relative risk (RR) for postoperative nausea and vomiting (PONV) [RR 5.0, 95% CI (1.12 to 22.27); P = 0.03]. The perineural administration of buprenorphine provided a longer duration of analgesia than an intramuscular application [mean difference 6.87 h, 95% CI (4.02 to 9.71); P < 0.01] without evidence of a difference in the incidence of PONV between the modes of administration [RR 0.76, 95% CI (0.28 to 2.03); P = 0.58]. CONCLUSION: This meta-analysis revealed that the addition of buprenorphine to a local anaesthetic peripheral nerve block prolongs postoperative analgesia for about 8 h but significantly increases the risk for PONV. Perineural administration is more effective than systemic application but is associated with a similar risk of PONV. However, these results were influenced by heterogeneity so that further trials (especially head-to-head comparisons) are needed in the future. TRIAL REGISTRATION: PROSPERO(www.crd.york.ac.uk) identifier: CRD42016036054.

Monitoring heart rate variability to assess experimentally induced pain using the analgesia nociception index: A randomised volunteer study.

BACKGROUND: Pain assessment using a numerical rating scale (NRS) is considered good clinical practice, but objective assessment in noncommunicating patients is still a challenge. A potential solution is to monitor changes in heart rate variability transformed into the analgesia nociception index (ANI), that offers a noninvasive means of pain quantification. OBJECTIVES: The aim was to measure magnitudes, descending slopes and time courses of ANI following expected and unexpected painful, nonpainful and sham experimental stimuli and compare these with pain intensity as assessed by NRS in conscious human volunteers. We expected a negative correlation between ANI and NRS after painful stimuli. DESIGN: Randomised stimuli and placebo-controlled, single-blinded study. SETTING: Experimental pain simulation laboratory, Bochum, Germany. PARTICIPANTS: Twenty healthy male students, (mean ±â€Šstandard deviation; 24.2 ±â€Š1.9 years) recruited via local advertising, were consecutively included. INTERVENTION: ANI values were continuously recorded. After resting, four stimuli were applied in a random order on the right forearm (unexpected and expected electrical pain, expected nonpainful and sham stimuli). Blinded volunteers were asked to rate all four stimuli on NRS. MAIN OUTCOME MEASURES: ANI means (0-100), amplitudes, maxima, minima and slopes with NRS pain intensity scores (0-10). RESULTS: Resting alert volunteers showed ANI values of 82.05 ±â€Š10.71. ANI decreased after a random stimulus (maximal decrease of 25.0 ±â€Š7.3%), but different kinds of stimuli evoked similar results. NRS scores (median; interquartiles) were significantly (P = 0.008) higher after expected (5.25; 3.5-6.75) compared with unexpected (4.50; 3.0-5.0) pain stimuli. No correlation was found between ANI and NRS. CONCLUSION: ANI did not allow a differentiation of painful, nonpainful or sham stimuli in alert volunteers. Therefore, ANI does not exclusively detect nociception, but may be modified by stress and emotion. Thus, we conclude that ANI is not a specific, robust measure for assessment of pain intensity.

Age- and procedure-specific differences of epidural analgesia in children--a database analysis.

OBJECTIVE: Several audits demonstrated the safety of epidural catheters in children undergoing surgery. Within the present data analysis, we investigated whether older compared with younger children and children with specific types of surgical procedures might report higher pain scores. METHODS: All children (0-18 years) treated with an epidural catheter for postoperative pain treatment between March 2006 and December 2010 at the University Hospital of Muenster (Germany) were included. Postoperative pain intensities, the number of patients with the need for additional opioids, and catheter-related complications during placement and early postoperative period were analyzed. RESULTS: Data of 830 children receiving an epidural catheter (Nthoracic/lumbar = 691; Ncaudal = 139) were included. Adolescents (12-18 years) treated with a thoracic/lumbar epidural had higher pain scores compared with preschoolers and school children (P < 0.05) and received less additional systemic opioids (P < 0.001). In the thoracic/lumbar epidural group, children undergoing spine surgery showed comparable pain scores with those undergoing thoracic procedures, but had higher pain scores than children undergoing abdominal or extremity surgery (P < 0.05). However, children undergoing spine surgery received less additional opioids, but this was only significant at the first postoperative day (P = 0.032). CONCLUSIONS: This database analysis demonstrated that older children and children undergoing thoracic or spine surgery reported significant higher pain scores most likely because they received less additional opioids. Therefore, a more "aggressive" pain treatment (including opioids on demand under appropriate monitoring) might further improve postoperative care.

Tramadol for postoperative pain treatment in children.

BACKGROUND: According to current recommendations a multimodal approach is believed to be the gold standard for postoperative pain treatment in children. However, several surveys in the last few years demonstrated that postoperative pain in children is still a serious problem, mainly because opioids are avoided. One of the reasons for this is the fear of severe adverse events following opioid administration. Tramadol is a weak mu-opioid agonist and inhibits reuptake of noradrenaline and serotonin (5HT). Because of a relatively wide therapeutic window and a ceiling effect with a lower risk for severe adverse events (for example respiratory depression) tramadol is a widely used opioid in children. However, the exact efficacy and occurrence of adverse events following tramadol (in comparison with placebo or other opioids) for postoperative pain treatment in children and adolescents are currently not clear. OBJECTIVES: To assess the effectiveness and side effect profile of tramadol for postoperative pain relief in children and adolescents undergoing different surgical procedures. SEARCH METHODS: We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2014, Issue 6), MEDLINE via PubMed (January 1966 to July 2014) and EMBASE via Ovid (January 1947 to July 2014). There were no restrictions regarding language or date of publication. The reference lists of all included trials were checked for additional studies. SELECTION CRITERIA: All randomised controlled clinical trials investigating the perioperative administration of tramadol compared to placebo or other opioids for postoperative pain treatment in children and adolescents were included. DATA COLLECTION AND ANALYSIS: Three review authors independently assessed the study eligibility, performed the data extraction and assessed the risk of bias of included trials. MAIN RESULTS: Twenty randomised controlled trials involving 1170 patients were included in this systematic review. The overall risk of bias in included trials was assessed as unclear, because concealment of allocation processes and blinding of outcome assessors were poorly described. Due to inconsistent outcome reporting, data from 17 included trials could be pooled for some endpoints only. Eight trials compared tramadol administration with placebo and five trials found that the need for rescue analgesia in the postoperative care unit (PACU) was reduced in children receiving tramadol (RR 0.40; 95% CI 0.20 to 0.78; low quality evidence). Only one trial investigated the number of patients with moderate to severe pain, but a non-validated pain scale was used (very low quality evidence). Four trials compared morphine with tramadol administration. There was no clear evidence of difference in the need for rescue analgesia in the PACU (RR 1.25; 95% CI 0.83 to 1.89; low quality evidence) with tramadol compared with morphine. No trials could be pooled for the outcome 'number of patients with moderate to severe pain'. Three trials were included for the comparison of tramadol with nalbuphine. There was no clear evidence for the need for rescue analgesia in the PACU (RR 0,63; 95% CI 0.16 to 2.45; low quality evidence). Only one trial reported the number of patients with moderate to severe pain, but used a non-validated pain scale (very low quality evidence). Two out of six included trials, which compared pethidine with tramadol, reported the number of children with a need for rescue analgesia within the PACU and showed no clear evidence (RR 0.93; 95% CI 0.43 to 2.02; very low quality evidence). Two trials reported the number of patients with moderate to severe pain and showed a lower RR in patients treated with tramadol (RR 0.64; 95% CI 0.36 to 1.16; low quality evidence). Only one trial was included, which compared tramadol with fentanyl, reporting the number of patients with the need for rescue analgesia (very low quality evidence). Generally, adverse events were poorly reported. Most data could be pooled for the comparison with placebo focusing on the RR for postoperative nausea and vomiting (PONV) in the postoperative care unit and 24 h postoperation. Children treated with tramadol, compared to placebo, did not show clear evidence of benefit for PONV in the postoperative care unit (RR 0.84; 95% CI 0.28 to 2.52; moderate quality evidence) and 24 h postoperation (RR 0.78; 95% CI 0.54 to 1.12; moderate quality evidence). AUTHORS' CONCLUSIONS: The overall evidence regarding tramadol for postoperative pain in children is currently low or very low and should be interpreted with caution due to small studies and methodological problems (different validated and non-validated pain scales with different pain triggers, missing sample size calculations and missing intention-to-treat analysis). Nevertheless, we demonstrated that tramadol administration might provide appropriate analgesia when compared to placebo; this is based on results showing reduced rescue analgesia in children treated with tramadol compared to placebo. In contrast, the evidence regarding the comparison with other opioids (for example morphine) was uncertain. Adverse events were only poorly reported, so an accurate risk-benefit analysis was not possible.

Effect of remote ischemic preconditioning on kidney injury among high-risk patients undergoing cardiac surgery: a randomized clinical trial.

IMPORTANCE: No interventions have yet been identified to reduce the risk of acute kidney injury in the setting of cardiac surgery. OBJECTIVE: To determine whether remote ischemic preconditioning reduces the rate and severity of acute kidney injury in patients undergoing cardiac surgery. DESIGN, SETTING, AND PARTICIPANTS: In this multicenter trial, we enrolled 240 patients at high risk for acute kidney injury, as identified by a Cleveland Clinic Foundation score of 6 or higher, between August 2013 and June 2014 at 4 hospitals in Germany. We randomized them to receive remote ischemic preconditioning or sham remote ischemic preconditioning (control). All patients completed follow-up 30 days after surgery and were analyzed according to the intention-to-treat principle. INTERVENTIONS: Patients received either remote ischemic preconditioning (3 cycles of 5-minute ischemia and 5-minute reperfusion in one upper arm after induction of anesthesia) or sham remote ischemic preconditioning (control), both via blood pressure cuff inflation. MAIN OUTCOMES AND MEASURES: The primary end point was the rate of acute kidney injury defined by Kidney Disease: Improving Global Outcomes criteria within the first 72 hours after cardiac surgery. Secondary end points included use of renal replacement therapy, duration of intensive care unit stay, occurrence of myocardial infarction and stroke, in-hospital and 30-day mortality, and change in acute kidney injury biomarkers. RESULTS: Acute kidney injury was significantly reduced with remote ischemic preconditioning (45 of 120 patients [37.5%]) compared with control (63 of 120 patients [52.5%]; absolute risk reduction, 15%; 95% CI, 2.56%-27.44%; P = .02). Fewer patients receiving remote ischemic preconditioning received renal replacement therapy (7 [5.8%] vs 19 [15.8%]; absolute risk reduction, 10%; 95% CI, 2.25%-17.75%; P = .01), and remote ischemic preconditioning reduced intensive care unit stay (3 days [interquartile range, 2-5]) vs 4 days (interquartile range, 2-7) (P = .04). There was no significant effect of remote ischemic preconditioning on myocardial infarction, stroke, or mortality. Remote ischemic preconditioning significantly attenuated the release of urinary insulinlike growth factor-binding protein 7 and tissue inhibitor of metalloproteinases 2 after surgery (remote ischemic preconditioning, 0.36 vs control, 0.97 ng/mL2/1000; difference, 0.61; 95% CI, 0.27-0.86; P < .001). No adverse events were reported with remote ischemic preconditioning. CONCLUSIONS AND RELEVANCE: Among high-risk patients undergoing cardiac surgery, remote ischemic preconditioning compared with no ischemic preconditioning significantly reduced the rate of acute kidney injury and use of renal replacement therapy. The observed reduction in the rate of acute kidney injury and the need for renal replacement warrants further investigation. TRIAL REGISTRATION: German Clinical Trials Register Identifier: DRKS00005333.

Nalbuphine for postoperative pain treatment in children.

BACKGROUND: Several surveys over the past few years have demonstrated that postoperative pain in children is not treated appropriately. One pharmacological treatment option in a multimodal approach for postoperative pain treatment is the systemic administration of opioids. However, opioids are rarely used for postoperative pain treatment in children due to fear of adverse events. One long-standing opioid for systemic use is nalbuphine, a kappa-receptor agonist and µ-receptor antagonist. The efficacy of nalbuphine is believed to be similar to morphine. Increased dosing might result in a ceiling effect, and thus less analgesia than expected. In addition, there might be a lower risk for opioid-induced side effects (nausea, vomiting) and severe adverse events (respiratory depression) due to the antagonistic effect of the µ-receptor. Nalbuphine may be an useful opioid for postoperative use in children, but exact efficacy (e.g. compared to other commonly used opioids) has not been determined yet. OBJECTIVES: To assess the efficacy and adverse events of nalbuphine for acute postoperative pain treatment in children undergoing surgery. SEARCH METHODS: We systematically searched the following databases: The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 7), MEDLINE via Pubmed (January 1966 to July 2013) and EMBASE via Ovid (January 1947 to July 2013). We did not impose any restrictions regarding language or publication date. We checked all reference lists of retrieved articles for additional references. SELECTION CRITERIA: All randomised controlled trials (RCTs) investigating nalbuphine compared with placebo or other opioids were included. DATA COLLECTION AND ANALYSIS: Two review authors independently scanned the retrieved articles and made a decision regarding inclusion or exclusion of studies for this review. The same authors also performed the data extraction and the assessment of risk of bias. MAIN RESULTS: Ten RCTs including 658 patients were finally included in this systematic review. Five trials compared nalbuphine with placebo. Data from one out of five studies for the outcome moderate/severe pain following nalbuphine compared to placebo gave a risk ratio (RR) 1 hour postoperatively (postop) of 0.1 (95% confidence interval (CI) 0.01 to 0.71; low quality evidence) and a RR 2 hours postop of 0.14 (95% CI 0.02 to 1.06; low quality evidence). The estimated RR based on data from a single study indicated that nalbuphine reduced the requirement for analgesia two hours postop (RR 0.47; 95% CI 0.27 to 0.84; low quality evidence). Two included trials compared nalbuphine with morphine and showed a nonsignificant lower or comparable RR for moderate/severe pain at 1 hour postop (RR 0.84; 95% CI 0.12 to 5.74; low quality evidence), and 2 hours postop (RR 1.09; 95% CI 0.59 to 2.01; low quality evidence) for nalbuphine versus morphine. Four trials compared nalbuphine with tramadol for postoperative pain; data from one trial (per outcome) revealed a lower but nonsignificant RR for the need of additional rescue analgesics in children receiving nalbuphine (RR 2 hours postop 0.75; 95% CI 0.39 to 1.43; low quality evidence) (RR 12 hours postop 0.33; 95% CI 0.04 to 2.77; low quality evidence). One out of three trials comparing nalbuphine with pethidine demonstrated that the RR was not significantly lower following nalbuphine administration compared to pethidine (RR 2 hours postop 1.07; 95% CI 0.52 to 2.23; low quality evidence) (RR 24 hours postop 1.13; 95% CI 0.52 to 2.44; very low quality evidence). The most common adverse event was postoperative nausea and vomiting (PONV). Only one included trial reported that the RR for PONV in the postoperative care unit (PACU) was not significantly higher following nalbuphine compared to placebo (RR 1.00; 95% CI 0.16 to 6.42; low quality evidence) nor to morphine (RR 1.33; 95% CI 0.64 to 2.77; low quality evidence). AUTHORS' CONCLUSIONS: Because the overall quality of available evidence was low, this systematic review could not definitively show that the analgesic efficacy of nalbuphine is superior compared to placebo. Furthermore, due to the lack of significant results the comparison with other common opioids is also unclear. The same holds true for the evidence focusing on adverse events following nalbuphine compared to placebo or other opioid administration. The evidence is limited, because studies did not report conclusively all important postoperative pain outcomes (e.g. number of patients with the need for rescue analgesia, postoperative pain scores). Thus, a quantitative analysis was not possible for many major aspects (e.g. rescue analgesia, pain scores) and heterogeneity could not be further explored.

Regional analgesia techniques for total knee replacement.

PURPOSE OF REVIEW: Pain following total knee arthroplasty is a challenging task for healthcare providers. Concurrently, fast recovery and early ambulation are required to regain function and to prevent postoperative complications. Ideal postoperative analgesia provides sufficient pain relief with minimal opioid consumption and preservation of motor strength. Regional analgesia techniques are broadly used to answer these expectations. Femoral nerve blocks are performed frequently but have suggested disadvantages, such as motor weakness. The use of lumbar epidurals is questioned because of the risk of epidural hematoma. Relatively new techniques, such as local infiltration analgesia or adductor canal blocks, are increasingly discussed. The present review discusses new findings and weight between known benefits and risks of all of these techniques for total knee arthroplasty. RECENT FINDINGS: Femoral nerve blocks are the gold standard for total knee arthroplasty. The standard use of additional sciatic nerve blocks remains controversial. Lumbar epidurals possess an unfavourable risk/benefit ratio because of increased rate of epidural hematoma in orthopaedic patients and should be reserved for lower limb amputation; peripheral regional techniques provide comparable pain control, greater satisfaction and less risk than epidural analgesia. Although motor weakness might be greater with femoral nerve blocks compared with no regional analgesia, new data point towards a similar risk of falls after total knee arthroplasty with or without peripheral nerve blocks. Local infiltration analgesia and adductor canal blockade are promising recent techniques to gain adequate pain control with a minimum of undesired side-effects. SUMMARY: Femoral nerve blocks are still the gold standard for an effective analgesia approach in knee arthroplasty and should be supplemented (if needed) by oral opioids. An additional sciatic nerve blockade is still controversial and should be an individual decision. Large-scale studies are needed to reinforce the promising results of newer regional techniques, such as local infiltration analgesia and adductor canal block.

Efficacy and safety of intraoperative dexmedetomidine for acute postoperative pain in children: a meta-analysis of randomized controlled trials.

BACKGROUND: Aim of the current meta-analysis was to assess the effects of intraoperative dexmedetomidine on postoperative pain, analgesic consumption, and adverse events in comparison with placebo or opioids in children undergoing surgery. METHODS: This meta-analysis was performed according to the recommendations of the PRISMA statement and the Cochrane collaboration. For dichotomous and continuous outcomes of efficacy and adverse events, the Revman(®) (The Nordic Cochrane Centre, Copenhagen, Denmark) statistical software was used to calculate relative risk (RR), mean difference (MD), and 95% confidence intervals (CI). RESULTS: We included 11 randomized controlled trials - 434 children received dexmedetomidine, 440 received control. In comparison with placebo, children receiving dexmedetomidine showed a reduced RR for postoperative opioids (0.4; 95% CI: 0.26-0.62; P < 0.00001) and postoperative pain (0.51; 95% CI: 0.32-0.81; P = 0.004). Similar results were obtained for the comparison with intraoperative opioids: reduced RR for postoperative pain (0.49; 95% CI: 0.25-0.94; P = 0.03) and the need for postoperative opioids (0.77; 95% CI: 0.60-1.09; P = 0.05). CONCLUSIONS: This meta-analysis revealed a lower risk for postoperative pain and the need for postoperative opioids following intraoperative dexmedetomidine in comparison with placebo or opioids in children undergoing surgery; however, the influence of dexmedetomidine on postoperative opioid consumption is less clear. Although there were only a limited number of adverse events, further studies focusing on procedure specific dexmedetomidine dosing and adverse events are urgently needed.