Evaluating the ability of non-rectangular electrical pulse forms to preferentially activate nociceptive fibers by comparing perception thresholds

Evaluating the ability of non-rectangular electrical pulse forms to preferentially activate... Scientific presentations at the 2017 Annual Meeting / Scandinavian Journal of Pain 16 (2017) 165–188Renal function estimations and doserecommendations for Gabapentin, Ibuprofenand Morphine in acute hip fracture patientsEvaluating the ability of non-rectangularelectrical pulse forms to preferentially activatenociceptive fibers by comparing perceptionthresholdsM.B. Houlind a,b,c,∗ , C. Treldal a,b , M. Aakjær a,b,c ,H. Palm d , B. Malmquist d , O. Andersen a , L.L.Christrup d , K.K. Petersen eR. Hugosdottir a,b,∗ , C.D. Mørch a,b , O.K.Andersen a,b , T. Helgason a,b , L. Arendt-Nielsen a,baaOptimed, Clinical Research Center, HvidovreHospital, The Capital Region of Denmark,Copenhagen, Denmarkb The Hospital Pharmacy, Copenhagen UniversityHospital, The Capital Region of Denmark, Denmarkc Department of Pharmacology andPharmacotherapy, Faculty of PharmaceuticalSciences, University of Copenhagen, Copenhagen,Denmarkd Department of Orthopaedic Surgery, HvidovreHospital, The Capital Region of Denmark, Denmarke SMI, Department of Health Science and Technology,Aalborg University, Aalborg, DenmarkE-mail address: morten.baltzer.houlind@regionh.dk (M.B. Houlind).Aims: Optimization of pain management is essential for fasttrack surgery and safety in acute hip fracture (AHF) patients. Kidneyfunction determines the doses of several postoperative painkillers,but previous studies have shown the standard Chronic KidneyDisease Epidemiology Collaboration (CKD-EPI) equation overestimate glomerular filtration rate (GFR) in elderly and underweightpatients. The optimized Cockcroft Gault (CGop) equation might bemore accurate in this patient group. The study aims to (1) investigate the differences in estimated GFR (eGFR) based on CKD-EPI andCGop and (2) to simulate this impact on recommended dosing ofstandard painkillers in AHF patients.Methods: Patients admitted with AHF from January to April2015 were included. eGFR was calculated for each patient byCKD-EPI and CGop based on the lowest measured serum creatinine between 1 and 4 days postoperatively. CKD-classification(1–5) was performed based on both eGFR values. If patients wereclassified differently based on the two eGFR values, then drugdosages were simulated for Morphine, Ibuprofen and Gabapentin®according to prescribing recommendations in Renbase . Two-sidedMann–Whitney test was used to compare median values betweengroups.Results: 176 patients (62% women) with a median age of76 years were included. CKD-EPI (78.0 mL/min/m2 ) estimatedeGFR significantly higher compared with GGop (58.9, P < 0.001).Depending on the equation used to estimate GFR, CKD ≥ 3(eGFR < 60 mL/min/m2 ) occurred in 23–53% all patients. Using CGopto estimate GFR resulted in CKD re-classification for 63% of allpatients. Using CKD-EPI to estimate GFR resulted in significantlyhigher doses of Morphine, Ibuprofen and Gabapentin (P < 0.0001)in re-classified patients.Conclusions: GFR estimates are significantly higher when calculated by CKD-EPI compared to CGop, and this difference resultsin significantly higher recommended doses of painkillers in AHFpatients. Future studies should include a gold standard for measuring GFR and maybe alternative biomarkers for the renal function.http://dx.doi.org/10.1016/j.sjpain.2017.04.031175Department of Health Science and Technology, SMI,Center of Neuroplasticity and Pain, AalborgUniversity, Aalborg, Denmarkb School of Engineering and Science, ReykjavikUniversity, Reykjavik, IcelandE-mail address: rhugos@hst.aau.dk (R. Hugosdottir).Aims: Selective activation of nociceptive fibers is difficult usingelectrical stimulation as the activation threshold is higher than fornon-nociceptive fibers. It remains unclear to what extent accommodation of non-nociceptive fibers during slowly rising electricalpulses can be utilized to reverse this activation order. The aim of thisstudy was to evaluate the ability of different pulse forms to activatenociceptive fibers with minimal co-activation of non-nociceptivefibers by comparing subjective perception thresholds (PT).Methods: Electrical pulses were applied on the volar forearm of25 subjects with (1) small diameter pin electrodes providing highcurrent density in the skin epidermis, where primarily nociceptive fibers terminate and (2) standard patch electrodes (2.63 cm2 ).PTs were obtained for exponential current increase, linear currentincrease, increasing form of exponential current decay (ED), andstandard rectangular current pulses. All pulse forms were tested attwo relatively long durations (5 and 50 ms). The PT ratio betweenpatch- and pin electrode was calculated as an estimate of the ability of a pulse form to preferentially activate nociceptive fibers. Theshort form McGill pain questionnaire (SF-MPQ) was used to assessperceived quality of pain for all pulse forms.Results: For the pin electrode, PT tended to decrease withincreasing pulse area. Patch electrode PT tended to increase forincreasing pulse area for non-rectangular 50 ms pulses, in contrast to 5 ms pulses, indicating accommodation of non-nociceptivefibers. Largest PT ratio was obtained for the 50 ms ED. SF-MPQscores were higher for the pin- compared to the patch electrode.Pin electrode pain qualities were mainly described as stabbing andsharp. SF-MPQ scores did not differ between pulse forms.Conclusions: Long duration ED pulses seem to activate nociceptive fibers better than regular, short duration pulses; most likelyreflecting accommodation of non-nociceptive fibers.http://dx.doi.org/10.1016/j.sjpain.2017.04.032Detection of systemic inflammation in severelyimpaired chronic pain patients, and effects of aCBT-ACT-based multi-modal pain rehabilitationprogramE.-B. Hysing a,∗ , L. Smith a , M. Thulin b , R.Karlsten a , T. Gordh aaMultidisciplinary Pain Center, Uppsala UniversityHospital, Uppsala, Swedenb Department of Statistics, Uppsala University,SwedenE-mail address: eva-britt.hysing@akademiska.se (E.-B. Hysing).Aims: A few previous studies indicate an ongoing of low-gradesystemic inflammation in chronic pain patients (CPP) [1,2]. In thepresent study we investigated the plasma inflammatory profile inseverely impaired chronic pain patients. In addition we studied ifthere were any alterations in inflammation patterns at one-year http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Scandinavian Journal of Pain de Gruyter

Evaluating the ability of non-rectangular electrical pulse forms to preferentially activate nociceptive fibers by comparing perception thresholds

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De Gruyter
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© 2017 Scandinavian Association for the Study of Pain
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1877-8860
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1877-8879
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10.1016/j.sjpain.2017.04.032
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Abstract

Scientific presentations at the 2017 Annual Meeting / Scandinavian Journal of Pain 16 (2017) 165–188Renal function estimations and doserecommendations for Gabapentin, Ibuprofenand Morphine in acute hip fracture patientsEvaluating the ability of non-rectangularelectrical pulse forms to preferentially activatenociceptive fibers by comparing perceptionthresholdsM.B. Houlind a,b,c,∗ , C. Treldal a,b , M. Aakjær a,b,c ,H. Palm d , B. Malmquist d , O. Andersen a , L.L.Christrup d , K.K. Petersen eR. Hugosdottir a,b,∗ , C.D. Mørch a,b , O.K.Andersen a,b , T. Helgason a,b , L. Arendt-Nielsen a,baaOptimed, Clinical Research Center, HvidovreHospital, The Capital Region of Denmark,Copenhagen, Denmarkb The Hospital Pharmacy, Copenhagen UniversityHospital, The Capital Region of Denmark, Denmarkc Department of Pharmacology andPharmacotherapy, Faculty of PharmaceuticalSciences, University of Copenhagen, Copenhagen,Denmarkd Department of Orthopaedic Surgery, HvidovreHospital, The Capital Region of Denmark, Denmarke SMI, Department of Health Science and Technology,Aalborg University, Aalborg, DenmarkE-mail address: morten.baltzer.houlind@regionh.dk (M.B. Houlind).Aims: Optimization of pain management is essential for fasttrack surgery and safety in acute hip fracture (AHF) patients. Kidneyfunction determines the doses of several postoperative painkillers,but previous studies have shown the standard Chronic KidneyDisease Epidemiology Collaboration (CKD-EPI) equation overestimate glomerular filtration rate (GFR) in elderly and underweightpatients. The optimized Cockcroft Gault (CGop) equation might bemore accurate in this patient group. The study aims to (1) investigate the differences in estimated GFR (eGFR) based on CKD-EPI andCGop and (2) to simulate this impact on recommended dosing ofstandard painkillers in AHF patients.Methods: Patients admitted with AHF from January to April2015 were included. eGFR was calculated for each patient byCKD-EPI and CGop based on the lowest measured serum creatinine between 1 and 4 days postoperatively. CKD-classification(1–5) was performed based on both eGFR values. If patients wereclassified differently based on the two eGFR values, then drugdosages were simulated for Morphine, Ibuprofen and Gabapentin®according to prescribing recommendations in Renbase . Two-sidedMann–Whitney test was used to compare median values betweengroups.Results: 176 patients (62% women) with a median age of76 years were included. CKD-EPI (78.0 mL/min/m2 ) estimatedeGFR significantly higher compared with GGop (58.9, P < 0.001).Depending on the equation used to estimate GFR, CKD ≥ 3(eGFR < 60 mL/min/m2 ) occurred in 23–53% all patients. Using CGopto estimate GFR resulted in CKD re-classification for 63% of allpatients. Using CKD-EPI to estimate GFR resulted in significantlyhigher doses of Morphine, Ibuprofen and Gabapentin (P < 0.0001)in re-classified patients.Conclusions: GFR estimates are significantly higher when calculated by CKD-EPI compared to CGop, and this difference resultsin significantly higher recommended doses of painkillers in AHFpatients. Future studies should include a gold standard for measuring GFR and maybe alternative biomarkers for the renal function.http://dx.doi.org/10.1016/j.sjpain.2017.04.031175Department of Health Science and Technology, SMI,Center of Neuroplasticity and Pain, AalborgUniversity, Aalborg, Denmarkb School of Engineering and Science, ReykjavikUniversity, Reykjavik, IcelandE-mail address: rhugos@hst.aau.dk (R. Hugosdottir).Aims: Selective activation of nociceptive fibers is difficult usingelectrical stimulation as the activation threshold is higher than fornon-nociceptive fibers. It remains unclear to what extent accommodation of non-nociceptive fibers during slowly rising electricalpulses can be utilized to reverse this activation order. The aim of thisstudy was to evaluate the ability of different pulse forms to activatenociceptive fibers with minimal co-activation of non-nociceptivefibers by comparing subjective perception thresholds (PT).Methods: Electrical pulses were applied on the volar forearm of25 subjects with (1) small diameter pin electrodes providing highcurrent density in the skin epidermis, where primarily nociceptive fibers terminate and (2) standard patch electrodes (2.63 cm2 ).PTs were obtained for exponential current increase, linear currentincrease, increasing form of exponential current decay (ED), andstandard rectangular current pulses. All pulse forms were tested attwo relatively long durations (5 and 50 ms). The PT ratio betweenpatch- and pin electrode was calculated as an estimate of the ability of a pulse form to preferentially activate nociceptive fibers. Theshort form McGill pain questionnaire (SF-MPQ) was used to assessperceived quality of pain for all pulse forms.Results: For the pin electrode, PT tended to decrease withincreasing pulse area. Patch electrode PT tended to increase forincreasing pulse area for non-rectangular 50 ms pulses, in contrast to 5 ms pulses, indicating accommodation of non-nociceptivefibers. Largest PT ratio was obtained for the 50 ms ED. SF-MPQscores were higher for the pin- compared to the patch electrode.Pin electrode pain qualities were mainly described as stabbing andsharp. SF-MPQ scores did not differ between pulse forms.Conclusions: Long duration ED pulses seem to activate nociceptive fibers better than regular, short duration pulses; most likelyreflecting accommodation of non-nociceptive fibers.http://dx.doi.org/10.1016/j.sjpain.2017.04.032Detection of systemic inflammation in severelyimpaired chronic pain patients, and effects of aCBT-ACT-based multi-modal pain rehabilitationprogramE.-B. Hysing a,∗ , L. Smith a , M. Thulin b , R.Karlsten a , T. Gordh aaMultidisciplinary Pain Center, Uppsala UniversityHospital, Uppsala, Swedenb Department of Statistics, Uppsala University,SwedenE-mail address: eva-britt.hysing@akademiska.se (E.-B. Hysing).Aims: A few previous studies indicate an ongoing of low-gradesystemic inflammation in chronic pain patients (CPP) [1,2]. In thepresent study we investigated the plasma inflammatory profile inseverely impaired chronic pain patients. In addition we studied ifthere were any alterations in inflammation patterns at one-year

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Scandinavian Journal of Painde Gruyter

Published: Dec 29, 2017

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