ObjectiveWe aim to investigate the correlation between ongoing pain levels and pain threshold measured by algometry after bariatric surgery.MethodsA retrospective analysis was conducted on data from 150 patients who underwent bariatric surgery, including 120 who received Roux-en-Y gastric bypass (RYGB) and 30 who underwent sleeve gastrectomy. Shortly after surgery, pain was assessed by the visual analogue scale (VAS) and abdominal algometry. Algometry was performed on the most sensitive abdominal pressure points.ResultsPatients reported moderate pain after surgery, with a mean of VAS score of 5.7. The mean abdominal pain threshold was 9.8N. VAS pain scores correlated with algometry (Spearman correlation coefficient -0.35; p < 0.0001). No sex-specific differences were observed in postoperative pain (p = 0.45) or algometry (p = 0.99). Furthermore, RYGB and sleeve gastrectomy groups did not differ significantly in the Spearman correlation coefficients (p = 0.214).ConclusionsThe mild correlation between reduced mechanical pain thresholds and higher levels of ongoing pain confirms the clinical value of sensory pain testing in the postoperative setting and suggests that local mechanical sensitization contributes to ongoing pain.

Zusammenfassung Hintergrund Nach den Kriterien der Qualitätssicherungsvereinbarung Schmerztherapie (QSV) nahmen zum Stichtag 31.12.2016 1206 Ärztinnen und Ärzte an der ambulanten Versorgung chronischer Schmerzpatienten teil. Bei in weiten Teilen bestehender Unterversorgung chronischer Schmerzpatienten fehlen Daten zur Einschätzung der ambulanten Schmerztherapie durch die Schmerztherapeuten selbst. Methoden In einem Hybrid-Delphi-Verfahren wurde ein Fragebogen zur inhaltlichen, strukturellen und persönlichen Bewertung der ambulanten Schmerztherapie in Deutschland entwickelt. Mit diesem Instrument wurde eine internetbasierte Querschnittsbefragung von 281 QSV-Schmerzmedizinern aus vier Bundesländern (Berlin, Niedersachsen, Sachsen, Baden-Württemberg) und aller universitären Schmerzambulanzleiter ( n = 36) in Deutschland durchgeführt. Ergebnisse Die Befragung erzielte eine bereinigte Rücklaufquote von insgesamt 35,9 %. Bei den Schmerzambulanzleitern antworteten 66,7 %. Bei 91 % der Befragten lag der Anteil an chronisch Schmerzkranken in der Praxis bei über 70 %. 67,3 % geben an, mit ihrer Praxissituation zufrieden zu sein, auf der anderen Seite äußern 63,4 % ihre Unzufriedenheit mit der aktuellen Organisation der Schmerzmedizin in Deutschland insgesamt. Diese Unzufriedenheit zeigt sich vor allem in Bezug auf die Budgetregelungen (69,3 %), die Kooperation mit Psychotherapeuten (69,3 %) und die interdisziplinäre Vernetzung (50,5 %). Als gute Vorbereitung für den späteren Beruf werden die einjährige Weiterbildung bei einem Weiterbildungsbefugten (87,1 %) und die Teilnahme an dem Kurs „Psychosomatische Grundversorgung“ (90,1 %) bewertet. Vielfältige Freitextkommentare weisen darauf hin, dass die Ausbildung zu kurz und nicht ausreichend sei. Die Mehrheit der Befragten hält es sowohl aus Arztsicht (61,4 %) wie auch aus Patientensicht (54,5 %) für sinnvoll, einen Facharzt für Schmerzmedizin als Versorgungsmodell zu etablieren. 70,8 % der Schmerzambulanzleiter sprechen sich für eigenständige Strukturen mit eigenem Budget aus, 75,0 % geben an, dass ihre Ambulanz unter den aktuellen Bedingungen nicht kostendeckend arbeitet. In Bezug auf die aktuelle Ausbildungssituation berichten nur 39,7 % der QSV-Schmerztherapeuten in der Niederlassung, dass sie auch Ärzte ausbilden, 57,6 % von ihnen planen zudem, ihre Tätigkeit innerhalb der nächsten 10 Jahre aufzugeben. Schlussfolgerungen Die mangelnde Eigenständigkeit der Schmerzmedizin und die unzureichend ausgebauten ambulanten Versorgungsnetzwerke tragen dazu bei, dass Schmerztherapeuten mit vielen Aspekten ihrer Tätigkeit unzufrieden sind. Die Etablierung eines Facharztes für Schmerztherapie wird als eine gute Lösung für eine bessere schmerzmedizinische Versorgung und für die Nachwuchsproblematik gesehen.

Metamizol wird in vielen Ländern häufig perioperativ eingesetzt. Unsicherheit besteht jedoch hinsichtlich der möglichen Komplikation einer Agranulozytose. Bei fehlender Evidenz aus der Literatur hat eine Arbeitsgruppe Expertenempfehlungen zum perioperativen Einsatz von Metamizol erarbeitet und in einem strukturierten formalen Konsensusprozess verabschiedet. Anschließend wurden die Empfehlungen in den Präsidien der Fachgesellschaften beraten und konsentiert. Die Expertengruppe stimmt überein, dass Blutbildkontrollen zur Überwachung der Metamizoltherapie beim kurzfristigen perioperativen Einsatz und bei Patienten ohne entsprechende Risikofaktoren für eine Neutropenie kein Standard sein sollen. Medizinisches Personal soll über die Symptome einer Agranulozytose und das Vorgehen bei Verdacht auf eine Agranulozytose informiert sein. Mit einer Risikoaufklärung soll der Patient über die Gabe von Metamizol, das Nutzen-Risiko-Verhältnis und mögliche Alternativen aufgeklärt werden. Andere Nichtopioidanalgetika werden von der Expertengruppe hinsichtlich Nutzen und Risiken nicht günstiger eingestuft als Metamizol. Eine Sicherungsaufklärung soll erfolgen, wenn über einige Tage Metamizol verabreicht wurde und/oder Patienten mit einer laufenden Metamizolmedikation aus stationärer oder ambulanter Behandlung entlassen werden, da sich eine Agranulozytose auch einige Tage nach Absetzen von Metamizol manifestieren kann. Weitere Empfehlungen betreffen die Information des weiterbehandelnden Arztes und die Vermeidung einer Reexposition bei stattgehabter metamizolbedingter Blutbildveränderung. Die Empfehlungen der Expertengruppe sollen das medizinische Personal und die Patienten für eine adäquate perioperative Anwendung von Metamizol sensibilisieren.

The German health care system currently faces the challenge of having to provide continued high-quality care nationwide despite a shrinking pool of qualified physicians. Cooperation structures based on telemedicine can deliver around-the-clock expert knowledge even to regions having a weak infrastructure, and thereby improve the quality of care in a cost-effective and sustainable manner. In tele-intensive care medicine and tele-emergency medicine, a number of international studies arid projects in Germany demonstrated that there had been positive results in the care of seriously ill patients. As far as anaesthesiology is concerned, tele-consultations offer the possibility of tailor-made and immediate specialist supervision, ranging from pre-surgical risk evaluation all the way to post-anaesthesiologica I support. In the area of pain management, telemedicine can equally help to provide timely and individualised care. The Permanent Commission for Telemedicine of the German Society of Anaesthesiology and Intensive Care Medicine (DGAI) and the German Society of Telemedicine (DG Telemed) suggests a catalogue of minimum requirements for telemedical applications with the goal of facilitating the inclusion of these applications in standard care.

Background: Dipyrone (metamizole) is widely used for perioperative pain management in countries where it is marketed. However, uncertainty exists concerning the safe use of this drug, specifically considering the rare adverse event of an agranulocytosis. Methods: As evidence from published studies was lacking, an expert panel developed recommendations for the perioperative use of dipyrone. After a formal, structured consensus process, the recommendations were approved by the involved medical societies. Results: The panel agreed that blood cell counts shall not be standard for short-term perioperative use in patients unless they are at risk for neutropenia. The medical staff shall be aware of the symptoms and course of action when agranulocytosis is suspected. Patients shall be informed about the risks and benefits of dipyrone and about potential alternatives. The expert group concluded that dipyrone has a relatively positive risk-benefit ratio compared to other non-opioid analgesics. The group strongly recommended educating patients about the symptoms of agranulocytosis if they have received dipyrone over several days and/or treatment is to be continued after discharge, because agranulocytosis can occur several days after discontinuation of metamizole. Further recommendations refer to the information of the physician taking over the patient's care after discharge and the avoidance of re-exposure in patients having previously suffered from dipyrone-induced agranulocytosis. Conclusion: The group's recommendations shall be communicated in order to raise medical staff's and patients' awareness of the appropriate use of dipyrone in the perioperative period.

Erythromelalgia is a rare disease that is associated with hemato-oncological diseases or after taking certain drugs and toxins, but it can also occur as an independent clinical picture, for example, due to mutations in the sodiumchannel NaV1.7. Clinically, there is a characteristic triad of attacklike burning pain and skin redness in the area of the distal extremities, which can be alleviated by excessive cooling. The attacks are triggered by heat, exertion, and stress. The diagnosis is primarily made clinically and can be confirmed by genetic testing if a sodium channel NaV1.7 mutation is present. Important differential diagnoses are complex regional pain syndrome, the non-freezing cold injury, and small fiber neuropathies. Therapy is multidisciplinary and has to be planned individually and include physical therapy and psychotherapy as well as drug therapy as integral components.

Methods Twenty-four subjects were enrolled in this study. The magnitude of pain, axon reflex flare, and areas of pin-prick hyperalgesia and touch-evoked allodynia were assessed in two consecutive sessions; prior to, and 2 h after drug administration. This protocol was repeated after 1 week. Subjects were randomized to receive either paracetamol (2 g) or a placebo. Results In comparison to the placebo arm there were no significant effects of paracetamol on pain, hyperalgesia, allodynia, or axon reflex flare. Pain and flare responses were highly reproducible on the same day ( r = 0.77 and r = 0.79, respectively), and after 1 week ( r = 0.6 and r = 0.71, respectively). The correlation between areas of hyperalgesia and allodynia was, however, significantly improved when the protocol was repeated on the same day ( r = 0.8 and r = 0.75), as opposed to after a week ( r = 0.54 and r = 0.53). Discussion The electrical pain model is a well established method for the assessment of intravenously applied analgesics. In order to assess effects of orally applied drugs the model had to be modified: for the assessment of hyperalgesia and allodynia a protocol repeating the model within 1 day proved to have advantages over repetition after 1 week. Keywords Cross-over study design Pain Hyperalgesia Axon reflex Paracetamol 1 Introduction Central sensitization plays a key role in the development and maintenance of many chronic pain conditions [9,13,20] . A previous study established an electrical stimulation protocol as an experimental model to investigate central sensitization processes as well as acute pain in human beings [10] . A recent study, however, demonstrated a continuous decline of pain ratings and areas of hyperalgesia within one session of investigation. These findings were most likely due to the constant stimulation paradigm [11] . Repetition of the stimulation protocol in a 1-week-interval revealed a successive decline of hyperalgesia, whereas pain ratings remained at a constant level. This psycho-physical pattern was observed in two different models of acute pain and central sensitization [8,11] . The effects of intravenous analgesic drugs on experimentally evoked axon reflex flare, pain, and hyperalgesia have already been investigated using various electrical stimulation protocols [3,10,18] . Due to the fast onset of analgesia after intravenous application the drug, the effects could easily be tested in one session. Placebo sessions were usually performed at 1- or 2-week intervals. Such stimulation paradigm was not applicable to orally administered drugs. In the present study the stimulation protocol was modified to explore the efficacy of orally administered drugs. Two stimulation sessions were performed on 1 day at an interval of 4 h, and were repeated after a week. Thereby we aimed for a lower variation of pain and hyperalgesia. Koppert et al. could already demonstrate reduced hyperalgesia and allodynia following intravenous application of 1 g paracetamol on [12] . In the present study the effects of 2 g of orally administered paracetamol on pain, axon reflex flare, pin-prick hyperalgesia, and touch-evoked allodynia were investigated hypothesizing that the antihyperalgesic effect of oral paracetamol could be confirmed using the modified experimental protocol due to lower variability of hyperalgesia. 2 Methods 2.1 Subjects and study design The study was conducted at the University Hospital of Erlangen-Nuremberg. The study protocol was approved by the Ethics Committee of the University according to the Good Clinical Practice guidelines and the Declaration of Helsinki. Twenty-four healthy volunteers (12 males and 12 females) were recruited and introduced to the stimulation procedures described below. Each subject provided written informed consent prior to the participation in the study. The subjects underwent a routine medical and physical examination and were screened for drug abuse. Women were screened for pregnancy. A double-blind, placebo-controlled, cross-over design was utilised. Each subject received the electrical stimulation protocol on 2 different days, separated by 1 week. The previously described stimulation protocol [10] was performed twice on the same day, with the first session being in the morning and the following session 4 h later in the afternoon. The afternoon session was performed on the contra-lateral forearm ( Fig. 1 ). 2.2 Treatment and dose rationale Two hours prior to each afternoon session tablets containing either 2 g of paracetamol, or sucrose as placebo were swallowed with 150 ml still mineral water. In this experimental model it had been shown previously that 1 g of paracetamol administered intravenously attenuates hyperalgesia and allodynia [12] . After application of 2 g of paracetamol administered intravenously in healthy subjects the maximum plasma concentration lies between 235 and 521 mmol/l, which is far below the 1000 mmol/l threshold for potential hepatotoxity [16] . In the present study, therefore, 2 g of paracetamol was applied, instead of the recommended 1 g, in order to achieve better analgesia without jeopardising safety. 2.3 Study procedures As described previously [10] intradermally delivered constant current stimuli were used to induce an axon reflex flare, ongoing pain, pin-prick hyperalgesia and touch-evoked allodynia. Two intradermal electrodes (Dermal Dialysis, Erlangen, Germany) were inserted in the central volar forearm. Current pulses (pulse width 0.5 ms, 2 Hz) of alternating polarity were delivered via a constant current stimulator (DS7A mod, Digitimer, Hertforshire, United Kingdom). The current intensity was gradually increased targeting a pain rating of 5–6 on the 11-point numeric rating scale (NRS) with the endpoints 0 (no pain) and 10 (maximum pain imaginable). Current intensity was halted at this level for 2 min, during which the perceived pain gradually declined. After the 2-min stimulation period the estimated pain was documented. The current was then adjusted to gain a pain rating of 5–6 NRS again, kept constant for another 2 min, and followed by another pain rating of the subject. This procedure was repeated over 16 min, after which the current was kept constant for further 60 min. The stimulation pattern of consecutive current increase was recorded for each subject and was used in all subsequent sessions. 2.4 Psycho-physical assessment During the electrical stimulation protocol the subjects were asked to estimate the perceived intensity of ongoing pain on the NRS at 5-min intervals. The area of pin-prick hyperalgesia was measured at 20-min intervals using a hand-held von Frey filament, delivering a force of 450 mN. The borders of hyperalgesia were delineated by stimulating along four linear paths in radial orientation to the stimulation site (proximal vs. distal and lateral vs. medial). The measurements were started in an area of normal skin sensation and were continued in 0.5 cm steps towards the stimulation site. Subjects were instructed to report instantly any changes of sensation in terms of increased pain evoked by the filament. The area of touch-evoked allodynia was determined in 20-min intervals by gently stroking the skin surface with a hand-held cotton wool bud. The subjects were asked to report any new perception of pain or an unpleasant sensation. The areas of hyperalgesia and allodynia were indicated using a marker. The areas were calculated from the recorded distances, as described previously [2] . 2.5 Recording and analysis of the axon reflex flare Axon reflex vasodilatation was quantified by laser Doppler imaging (MoorLDI Ltd., Axminster, United Kingdom). A baseline image was recorded 20 min prior to the experimental protocol and at 20-min intervals after onset of the stimulation. Off- line analysis of skin blood flow was performed using dedicated software (MoorLDI Research Version 5.0, Axminster, United Kingdom), as described previously [5] . Mean flux and standard deviation were determined in a baseline image. Areas of axon reflex flare were determined as flux increase above the baseline scan exceeding 2 folds of the standard deviation. Flare area was assessed in each image of the sequence. 2.6 Statistical analysis All data were evaluated with Statistica7.1 software package (StatSoft, Tulsa, USA). Pain ratings, axon reflex flare, and areas of hyperalgesia and allodynia were calculated by analysis of variance (ANOVA). Variances of the mean ( s 2 ) between the sessions ( j 1 and j 2 ) were calculated as follows: s 2 ( j 1 , j 2 ) = i − sum[(AUC( i , j 1 ) − AUC( i , j 2 )) 2 ]/ n . Variances of the mean squares ( r 2 ) between the sessions were calculated as follows: r 2 ( j 1 , j 2 ) = s 2 ( j 1 , j 2 )/ s 2 (1,3), with AUC = area under curve; i = panelist-index; j = session-index; n = number of panelists (=24). p -Values less than 5% were considered as significant. All values were given as mean ± standard error of the mean (SEM). 3 Results 3.1 Gender variability and paracetamol effects There were no significant gender differences regarding flare development ( p = 0.26, ANOVA), pain ( p = 0.36), touch-evoked allodynia ( p = 0.30) or pin-prick hyperalgesia ( p = 0.91). Stimulation of the right or the left arm revealed no significant difference for flare ( p = 0.85, ANOVA), pain ( p = 0.22), allodynia ( p = 0.89) and hyperalgesia ( p = 0.80). A pre-treatment with paracetamol revealed no significant effect on flare ( p = 0.96), pain ( p = 0.7), allodynia ( p = 0.77), or pin-prick hyperalgesia ( p = 0.83) (data not shown). 3.2 Variability of axon reflex flare, pain, pin-prick hyperalgesia, and touch-evoked allodynia Pain ratings ( r = 0.86 and r = 0.68 for paracetamol and placebo, respectively), and axon reflex flare areas ( r = 0.72 and r = 0.87 for paracetamol and placebo, respectively) highly correlated between the two sessions performed on the same day within a 4-h interval ( Fig. 2 , left column). When pain ratings and flare areas were compared between the sessions repeated after 1 week there was a slightly higher variability for pain ratings ( r = 0.6) and axon reflex flare areas ( r = 0.71) ( Fig. 2 , right column). Similar to the results obtained for pain and axon reflex flare, areas of pin-prick hyperalgesia ( r = 0.86 and r = 0.75 for paracetamol and placebo, respectively) and touch-evoked allodynia ( r = 0.76 and r = 0.75 for paracetamol and placebo, respectively) were highly reproducible when electrical stimulation was repeated after 4 h ( Fig. 3 , left column). When electrical stimulation was repeated after 1 week there was still a significant correlation between the areas ( r = 0.54 and r = 0.53 for pin-prick hyperalgesia and touch-evoked allodynia, respectively). The correlation, however, was considerably less tight in comparison to the repetition of the test on the same day ( Fig. 3 , right column). There was no significant difference between pain ratings and areas of mechanical hypersensitivity when assessments were performed on the same day. When comparing pain and hyperalgesia induced in the morning sessions at a 1-week interval no significant differences for pain ( p = 0.44), hyperalgesia ( p = 0.11), and allodynia ( p = 0.82) were assessed, albeit there was a tendency to decline. Only the electrically induced flare area was slightly smaller when repeated at a 1-week interval (AUC session 1: 84.5 ± 21.9, AUC session 3: 71.0 ± 23.7, p = 0.045). In order to evaluate the differences in variability between different sessions, the variance for repetitions at 1-week interval was calculated ( Table 1 ). Variances for pain ratings, flare area and areas of mechanical hypersensitivity were lower when repetitions were performed on the same day. A particular reduction was observed for hyperalgesia that reached only 37–50% of the variation calculated for the 1-week interval. In contrast, variances of flare response were already pretty low for the 1-week interval and did only decrease to 57–80% when calculated for the repetition on the same day ( Table 1 ). 3.3 Adverse events All study treatments and procedures were tolerated well and no subject withdrew from the study. Each subject cooperated fully during the assessments. 4 Discussion The electrical stimulation used in the current study activates a subpopulation of mechano-insensitive C-nociceptors (silent nociceptors). This class of nociceptors is involved in the induction of axon reflex flare and secondary mechanical hyperalgesia [19] . The activation of the axons of the nociceptors using an electrical stimulation leads to a well controlled firing frequency of the nociceptors. The resulting action potentials are transmitted to the central synapses as well as to the peripheral terminals. At the peripheral terminals they induce the release of neuropetides, which in turn cause the development of an axon reflex flare. The assessment of this axon reflex flare is a valuable and an objective tool to test the activation of nociceptors. In addition to the peripheral effects, the central sensitization following continuous electrical stimulation can be assessed psycho-physically, measuring the development of hyperalgesia. Common analgesic drugs have shown to differential efficacy to attenuate electrically induced pain and hyperalgesia [2,10,17] . In addition to the development of secondary hyperalgesia around the stimulation electrodes, electrical stimulation or capsaicin injection also causes spreading mechanical hypesthesia [7] that can also be measured contra-laterally [4] and thus is assumed to be of central origin. In contrast to clinical pain, there is no evidence for contra-lateral spread of hyperalgesia in human pain models [4,7] . In the present study there was no significant effect of 2 g orally applied paracetamol on the magnitude of the estimated pain. This was in accordance with previous studies, in which pain thresholds to acute, noxious mechanical or thermal stimulation were not affected by this class of drugs [1,6,15] . Koppert et al. could demonstrate a significant attenuation of secondary hyperalgesia following intravenous administration of 1 g paracetamol [12] . This finding is of particular interest as it provides evidence for a spinal effect of paracetamol that is confined to a reduction of secondary mechanical hyperalgesia, but not to pain intensity. This pattern of antihyperalgesic effect has also been shown for gabapentin in the electrical human pain model [2,17] . In contrast to our expectations there was no significant reduction of hyperalgesia or allodynia after oral administration of 2 g paracetamol in the present study. The different result could be attributed to either pharmacokinetic differences or the experimental set up. Higher peak plasma concentrations upon intravenous injection might lead to higher central concentrations and hence more efficient antihyperalgesic activity. Higher central levels of paracetamol following intravenous injection as compared to oral application can be assumed regarding the higher occurrence of central side effects for the i.v. routes [14] . The onset of an analgesic effect can be expected by few minutes if paracetmol is applied intravenously [14] . An internal control without a drug infusion can therefore be easily performed within the same experimental session using the pre-injection baseline as a control level. This experimental set up can, however, not be easily used for the assessment of orally administered drugs for the following two reasons: (1) from an ethical point of view the duration of the experimental protocol may exceed the tolerance level of the recruited subjects; (2) a continuous stimulation leads to a gradual decline of the investigated parameters, in particular pain and hyperalgesia [11] . A similarly declining area of hyperalgesia was observed in the present study. This decline could be partly due to an endogenous opioid release, since in a previous work it could be shown that naloxone could prevent it [11] . In the present study, therefore, a cross-over design with two sessions on the same day, followed by two sessions a week later was chosen for the investigation of orally administered drugs. This experimental setting ensured an internal control between the sessions, revealed a high reproducibility of the analyzed parameters within 1 day, and, to a lesser extent, within 1 week. This study protocol could serve as an improved experimental setting for the analysis of the efficacy of analgesics on pain and hyperalgesia. 5 Conclusion A new experimental protocol of electrically induced pain and hyperalgesia was established to examine orally administered drugs. This experimental setting ensured an internal control between the sessions, revealed a high reproducibility of pain intensity and areas of mechanical hypersensitivity within 1 day and within 1 week. This study protocol could serve as an improved experimental setting for the analysis of the efficacy of analgesics on pain and hyperalgesia. Declaration of funding This study was funded by the Klinische Forschergruppe KFG 107 and the Kompetenzzentrum Schmerz , State Baden-Württemberg, Germany. Sponsoring preparation of the article has been provided by AstraZeneca , Sweden. Declaration of financial relationship There are no relationships to be declared. Conflict of interest None of the authors has any actual or potential conflict of interest concerning this work. Acknowledgement The authors gratefully acknowledge Niloufar Dusch for her editorial assistance. References [1] A. Bickel S. Dorfs M. Schmelz C. Forster W. Uhl H.O. Handwerker Effects of antihyperalgesic drugs on experimentally induced hyperalgesia in man Pain 76 1998 317 325 [2] B.A. Chizh M. Dusch M. Puthawala M. Schmelz L.M. Cookson R. Martina J. Brown W. Koppert The effect of intravenous infusion of adenosine on electrically evoked hyperalgesia in a healthy volunteer model of central sensitization Anesth Analg 99 2004 816 822 [table] [3] B.A. Chizh M. Gohring A. Troster G.K. Quartey M. Schmelz W. Koppert Effects of oral pregabalin and aprepitant on pain and central sensitization in the electrical hyperalgesia model in human volunteers Br J Anaesth 98 2007 246 254 [4] C.R. De C. Maihofner Centrally mediated sensory decline induced by differential C-fiber stimulation Pain 138 2008 556 564 [5] H. Eisenbarth R. Rukwied M. Petersen M. Schmelz Sensitization to bradykinin B1 and B2 receptor activation in UV-B irradiated human skin Pain 110 2004 197 204 [6] C. Forster W. Magerl A. Beck G. Geisslinger T. Gall K. Brune H.O. Handwerker Differential effects of dipyrone, ibuprofen, and paracetamol on experimentally induced pain in man Agents Actions 35 1992 112 121 [7] C. Geber W. Magerl R. Fondel M. Fechir R. Rolke T. Vogt R.D. Treede F. Birklein Numbness in clinical and experimental pain—a cross-sectional study exploring the mechanisms of reduced tactile function Pain 139 2008 73 81 [8] A. Hughes A. Macleod J. Growcott I. Thomas Assessment of the reproducibility of intradermal administration of capsaicin as a model for inducing human pain Pain 99 2002 323 331 [9] T.S. Jensen H. Gottrup S.H. Sindrup F.W. Bach The clinical picture of neuropathic pain Eur J Pharmacol 429 2001 1 11 [10] W. Koppert S.K. Dern R. Sittl S. Albrecht J. Schuttler M. Schmelz A new model of electrically evoked pain and hyperalgesia in human skin: the effects of intravenous alfentanil, S(+)-ketamine, and lidocaine Anesthesiology 95 2001 395 402 [11] W. Koppert J. Filitz A. Troster H. Ihmsen M. Angst H. Flor J. Schuttler M. Schmelz Activation of naloxone-sensitive and -insensitive inhibitory systems in a human pain model J Pain 6 2005 757 764 [12] W. Koppert A. Wehrfritz N. Korber R. Sittl S. Albrecht J. Schuttler M. Schmelz The cyclooxygenase isozyme inhibitors parecoxib and paracetamol reduce central hyperalgesia in humans Pain 108 2004 148 153 [13] M.J. Millan The induction of pain: an integrative review Prog Neurobiol 57 1999 1 164 [14] P.L. Moller S. Sindet-Pedersen C.T. Petersen G.I. Juhl A. Dillenschneider L.A. Skoglund Onset of acetaminophen analgesia: comparison of oral and intravenous routes after third molar surgery Br J Anaesth 94 2005 642 648 [15] K.L. Petersen J. Brennum J.B. Dahl Experimental evaluation of the analgesic effect of ibuprofen on primary and secondary hyperalgesia Pain 70 1997 167 174 [16] S.R. Rose Subtleties of managing acetaminophen poisoning Am J Hosp Pharm 51 1994 3065 3068 [17] M. Segerdahl Multiple dose gabapentin attenuates cutaneous pain and central sensitisation but not muscle pain in healthy volunteers Pain 125 2006 158 164 [18] A. Troster R. Sittl B. Singler M. Schmelz J. Schuttler W. Koppert Modulation of remifentanil-induced analgesia and postinfusion hyperalgesia by parecoxib in humans Anesthesiology 105 2006 1016 1023 [19] C. Weidner M. Schmelz R. Schmidt B. Hansson H.O. Handwerker H.E. Torebjork Functional attributes discriminating mechano-insensitive and mechano-responsive C nociceptors in human skin J Neurosci 19 1999 10184 10190 [20] C.J. Woolf G.J. Bennett M. Doherty R. Dubner B. Kidd M. Koltzenburg R. Lipton J.D. Loeser R. Payne E. Torebjork Towards a mechanism-based classification of pain? Pain 77 1998 227 229

BackgroundMechano-sensitive and mechano-insensitive C-nociceptors in human skin differ in receptive field sizes and electrical excitation thresholds, but their distinct functional roles are yet unclear.MethodsAfter blocking the lateral femoral cutaneous nerve (NCFL) in eight healthy male subjects (3-mL Naropin((R)) 1%), we mapped the skin innervation territory being anaesthetic to mechanical pin prick but sensitive to painful transcutaneous electrical stimuli. Such differentially anaesthetic zones' indicated that the functional innervation with mechano-sensitive nociceptors was absent but the innervation with mechano-insensitive nociceptors remained intact. In these areas, we explored heat pain thresholds, low pH-induced pain, cowhage- and histamine-induced itch, and axon reflex flare.ResultsIn differentially anaesthetic skin, heat pain thresholds were above the cut-off of 50 degrees C (non-anaesthetized skin 470.4 degrees C). Pain ratings to 30L pH 4 injections were reduced compared to non-anaesthetized skin (48 +/- 9 vs. 79 +/- 6 VAS; p<0.01). The axon reflex flare area did not differ between these zones (7.8 +/- 1.4cm(2) vs. 8.3 +/- 0.5cm(2)). Histamine iontophoresis still caused pruritus in differentially anaesthetized skin in five of eight subjects (VAS 26 +/- 14), whereas itch upon cowhage spicules was absent (VAS 0 vs. 29 +/- 11 in non-anaesthetized skin).ConclusionsWe conclude that activation of mechano-insensitive nociceptors is sufficient to provoke itch by histamine- and acid-induced pain. The mechano-sensitive nociceptors are crucial for cowhage-induced itch and for the assessment of heat pain thresholds.

Laser‐evoked potentials (LEP) were assessed after peripheral nerve block of the lateral femoral cutaneous nerve (LFCN) in healthy volunteers from partially anesthetized skin areas to differentially stimulate mechano‐insensitive nociceptors.

The introduction of pain medicine (cross-sectional subject 14, QF 14) into the Human Medicine study program is a great opportunity. A knowledge gap concerning the treatment of pain patients outside of specialized pain centers has been recognized for many years. This gap might be closed or at least reduced by a compulsory curriculum in pain medicine. If implementation of new lessons for QF 14 is not possible, pain medicine could be represented by labelled elements in the existing curriculum, in order to highlight the field. The core curriculum must now be converted into appropriate teaching and test formats. Due to the autonomy and heterogeneity of German medical faculties, no uniform solution will be achieved. In contrast, this diversity and the entirely new implementation of the cross-sectional subject will allow structured evaluation of different teaching and examination formats with respect to teaching outcome in benchmarking investigations in the coming semesters. Practically experienced lecturers and theory-driven medical educationalists are called upon to get involved with the development, implementation, and evaluation of pain medicine in undergraduate education in Germany. Teaching enthusiasts are encouraged to dedicate themselves to the strenuous, but stimulating task of implementing QF 14. The Deutsche Schmerzgesellschaft (German Pain Society) will offer support for this.

Die Einführung des neuen Querschnittsfachs 14 (QF 14) Schmerzmedizin ist eine große Chance. Die seit Langem beklagten Wissensdefizite in der Versorgung von Schmerzpatienten außerhalb von spezialisierten Zentren könnten durch die Pflichtlehre für alle Studierenden behoben oder zumindest reduziert werden. Bei unzureichenden Zeitressourcen für das eigentliche QF 14 können schmerzmedizinische Lehrinhalte auch im sonstigen Fakultätscurriculum kenntlich gemacht werden, um so das Gesamtcurriculum Schmerzmedizin in der Lehre sichtbar zu machen. Nun kommt es darauf an, die vorhandenen Lernzielempfehlungen des Kerncurriculums in adäquate Lehr- und Prüfungsformate zu überführen. Die Heterogenität der Lehrsituation an den deutschen medizinischen Fakultäten wird keine uniformen Lösungen zulassen, bietet aber dadurch und durch die vollständige Neuschaffung des Querschnittsfachs die Möglichkeit, die entstehenden unterschiedlichen Lehr- und Prüfungskonzepte hinsichtlich ihrer Effektivität im Sinne eines Benchmarkings in den kommenden Semestern strukturiert zu untersuchen. Praxiserfahrene Lehrverantwortliche sind zusammen mit theoriegeleiteten Ausbildungsforschern aufgerufen, sich dieser Aufgabe anzunehmen. Lehrenthusiasten werden ersucht, sich der anstrengenden, aber spannenden Aufgabe der QF-14-Implementierung zu widmen. Die Deutsche Schmerzgesellschaft e. V. wird diesen Prozess unterstützend begleiten.

Unrelieved pain is a substantial public health concern owing in part to deficits in clinical expertise among physicians. In most medical faculties worldwide, teaching on pain and pain management is either nonexistent or limited to a small number of students attending voluntary courses. In light of the fact that pain is the most frequent reason to seek medical advice, the lack of formal training of pain medicine is considered the leading reason for inadequate pain management. Therefore, the patients' unmet needs for adequate diagnosis and therapy call for action. Pain assessment and effective pain management should be a priority in the health care system. The limited number of pain specialists available in hospitals and primary care and CME (continuous medical education) activities focusing on pain are not sufficient to solve the problem. Every practicing physician should, therefore, have basic knowledge of the most prominent painful conditions and management strategies. To achieve this goal, pain medicine should become an integral part of the undergraduate curriculum for medical students. In Germany, pain medicine became a mandatory subject in undergraduate medical studies in 2012. The introduction of pain medicine into the undergraduate curriculum in Germany is a major challenge regarding the development and implementation processes. This article describes current instruments and implementation strategies for pain medicine as a new cross-sectional subject in Germany.

Background The aim of this randomised, clinical trial was to compare safety and efficiency of hyperbaric prilocaine and mepivacaine at a dosage of 0.5 ml each for perianal outpatient surgery in terms of transient neurologic symptoms (TNS) and postoperative recovery. Methods 160 patients aged 18–80 years were randomized to receive a spinal anaesthesia (SPA) with 0.5ml of mepivacaine or prilocaine. We measured the expansion of the block, evaluated postoperative recovery times and determined the incidence of TNS one week after surgery. Results 160 patients (93 male / 67 female) were available for analysis. Prilocaine led to shorter times from SPA to micturition (prilocaine: 178 (110–254) min vs. mepivacaine: 195 (130–305) min, p=0.0008) and discharge (prilocaine: 192 (126–267) min vs. mepivacaine: 220 (140–320) min, p<0.0001). 152 / 160 patients were available for the telephone follow-up. Six patients (9%) receiving mepivacaine compared to zero patients of the prilocaine group announced typical symptoms of TNS (p=0.0284). Conclusion Both, hyperbaric mepivacaine 40 mg/ml and hyperbaric prilocaine 20 mg/ml can be used at a dosage of 0.5 ml each for SPA in perianal outpatient surgery. Due to the faster recovery profile and a lower incidence of TNS, we recommend the use of 10mg hyperbaric prilocaine 20 mg/ml for this indication.

Professionals in the medical field are expected to participate in continuing medical education in the sense of lifelong learning. The authors took this occasion to evaluate the most important national convention in pain medicine concerning its role in medical education. The participants of the 37th German Pain Congress (17-20 October 2012 in Mannheim) were asked to complete a questionnaire concerning content and design of the convention. The aim of this study was to analyze the distribution of different physician competencies in the program. For this purpose the congress program was analyzed with respect to the various medical role models as defined in the Canadian medical education directions for specialists (CanMEDS) framework. The participants considered the quality of the different sessions of the German Pain Congress to be good. The poster sessions were considered to be the second most important educational format in the congress following the live sessions. Concerning the content of the congress the participants wished more emphasis on the role of interprofessional partners, such as nursing and psychotherapy. The CanMEDS physician roles of manager, communicator, health advisor and professional paragon were underrepresented in the congress program in this study. Regarding content and educational value, the congress design could benefit from additional Praktikerseminaren (practical seminars). The role of interprofessional partners should be more emphasized. In addition the program could become more attractive through a more balanced distribution of the CanMEDS roles.

Im Sinne des lebenslangen Lernens wird von allen in der Medizin tätigen Berufsgruppen eine kontinuierliche Weiterbildung erwartet. Dies nahmen die Autoren zum Anlass, den wichtigsten nationalen Kongress im Bereich der Schmerzmedizin aus medizindidaktischer Perspektive zu untersuchen.

Obwohl Schmerzen der bei Weitem häufigste Grund sind, einen Arzt aufzusuchen, konnten Ärzte ihre Ausbildung abschließen, ohne sich mit Schmerz und Schmerzmanagement auseinandergesetzt zu haben. Die resultierende Unsicherheit ist vermutlich einer der Hauptgründe, weshalb eine angemessene Behandlung unterbleibt. Viele Patienten beklagen daher zu Recht eine Ignoranz seitens des medizinischen Personals gegenüber ihrem Leiden.