Linköping University Medical Dissertations No. 1195 Effects of burns and vasoactive drugs on human skin, - Clinical and Experimental studies using microdialysis Anders Samuelsson Departments of Medicine and Health Sciences, Division of Drug Research/Anaesthesiology and Clinical and Experimental Medicine Faculty of Health Sciences Linköpings Univerity, S-581 85 Linköping. Sweden Linköping 2010 Copyright © Anders Samuelsson, 2010, unless otherwise noted Department of Medicine and Health Sciences Division of Drug Research/Anaesthesiology Faculty of Health Sciences Linköping University, SE-581 85 Sweden E-mail: [email protected] Printed in Sweden by LIU-tryck, Linköping, Sweden, 2010. Permission to print the published articles (paper I and II) is granted from the copyright holders. Permission to figure 1 from copyright© holder Johan Thorfinn, from Linköping University Medical Dissertation No.950 Cover illustration © CMA microdialysis, Stockholm, Sweden. Adapted to cover and text by Per Lagman, Mediacenter, Linköping. ISBN 978-91-7393-342-1 ISSN 0345-0082 To Annika, Karin and Erik “I started out with nothing and I still got most of it left” Seasick Steve Supervisor Folke Sjöberg, MD, PhD, Professor Department of Clinical and Experimental Medicine Faculty of Health Sciences Linköping University Opponent Ola Winsö, MD, PhD Professor Department of Surgery and Perioperative Sciences Division of Anaesthesiology and Intensive Care Medicine Umeå University Committee board Lars Berggren, MD, PhD, associated Professor Department of Clinical Medicine Örebro University Department of Anaesthesiology and Intensive Care Örebro University Hospital Jan Bolinder MD, PhD, Professor Department of Medicine, Karolinska University Hospital-Huddinge, Karolinska Institutet Stockholm Christina Eintrei, MD, PhD, Professor Department of Medicine and Health Sciences Division of Drug Research/Anaesthesiology Faculty of Health Sciences Linköping University Table of contents ABSTRACT________________________________________________________ 1 ABBREVIATIONS___________________________________________________ 3 INTRODUCTION____________________________________________________ 5 Background ___________________________________________________________________________ 5 SIRS/MODS___________________________________________________________________________ 5 Treatment_____________________________________________________________________________ 6 Microcirculatory changes_________________________________________________________________ 8 Skin _________________________________________________________________________________ 9 Models______________________________________________________________________________ 13 Serotonin ____________________________________________________________________________ 14 Noradrenalin__________________________________________________________________________ 15 Tissue metabolism_____________________________________________________________________ 17 Tissue monitoring______________________________________________________________________ 18 Orthogonal polarization spectral imaging (OPS)______________________________________________ 19 Microdialysis (MD)____________________________________________________________________ 20 AIMS OF THE STUDY_______________________________________________ 24 MATERIAL & METHODS ____________________________________________ 25 Subjects (Study I-IV) ____________________________________________________________________ 25 Microdialysis___________________________________________________________________________ 26 Microdialysis pumps ___________________________________________________________________ 27 Perfusion fluid________________________________________________________________________ 27 Sampling ____________________________________________________________________________ 28 Metabolic markers_____________________________________________________________________ 30 Blood flow measurements_________________________________________________________________ 30 Laser Doppler Perfusion Imaging (LDPI)___________________________________________________ 30 Urea clearance ________________________________________________________________________ 31 Serotonin (5HT) analysis________________________________________________________________ 31 Noradrenalin analysis___________________________________________________________________ 32 Drug protocols__________________________________________________________________________ 32 Data processing and statistics _____________________________________________________________ 34 RESULTS ________________________________________________________ 36 Study I________________________________________________________________________________ 36 Study II _______________________________________________________________________________ 38 Study III_______________________________________________________________________________ 40 Study IV_______________________________________________________________________________ 43 DISCUSSION______________________________________________________ 45 Monitoring skin metabolism in burns_______________________________________________________ 45 Microdialysis_________________________________________________________________________ 45 Control groups________________________________________________________________________ 46 Metabolites___________________________________________________________________________ 46 Review Study I__________________________________________________________________________ 46 Glucose______________________________________________________________________________ 48 Cytophatic hypoxia ____________________________________________________________________ 49 Lipolysis_____________________________________________________________________________ 49 Methodological considerations____________________________________________________________ 50 Review Study II_________________________________________________________________________ 51 Serotonin in burns _____________________________________________________________________ 51 Serotonin and microdialysis______________________________________________________________ 52 Serotonin kinetics______________________________________________________________________ 53 Study III_______________________________________________________________________________ 55 Measurement of blood flow changes_______________________________________________________ 55 Ethanol______________________________________________________________________________ 56 Urea________________________________________________________________________________ 56 Skin acidosis__________________________________________________________________________ 57 Modelling vascular responses in skin_______________________________________________________ 57 Review study III ________________________________________________________________________ 58 Glucose______________________________________________________________________________ 60 Lactate ______________________________________________________________________________ 61 Autoregulatory escape__________________________________________________________________ 62 Dose________________________________________________________________________________ 63 Review Study IV________________________________________________________________________ 63 Dose________________________________________________________________________________ 64 Dose response modelling________________________________________________________________ 65 Metabolism___________________________________________________________________________ 66 Drug protocol_________________________________________________________________________ 66 CONCLUSIONS____________________________________________________ 68 Future perspectives______________________________________________________________________ 69 Svensk sammanfattning__________________________________________________________________ 71 Acknowledgements______________________________________________________________________ 73 References_____________________________________________________________________________ 76 Abstract Samuelsson Anders. Effects of burns and vasoactive drugs on human skin, - Clinical and Experimental studies using microdialysis. Linköping University Medical Dissertation No. 1195, Ed: The Dean of Faculty of Health Sciences, Sweden 2010 Patients who require critical care, including those with burns, are affected by a systemic inflammatory reaction, which at times has consequences such as multiple organ dysfunction and failure. It has become increasingly evident that other factors important in the development of organ dysfunction are disturbances at the tissue level, in the microcirculation. Such disturbances activate cascade systems including stress hormones, all of which have local effects on organ function. Despite this knowledge, monitoring and treatment in critical illness today relies mainly on central haemodynamics and blood sampling. Microdialysis is a minimally invasive technique that enables us to study the chemical composition and changes in biochemistry in the extracellular, extravascular space in living tissues. Most of our current experience is from animal models, but the technique has also been used in humans and has become routine in many neurosurgical intensive care units to monitor brain biochemistry after severe injury. In skin, this experience is limited. During the first half of this thesis we studied the injured and uninjured skin of severely burned patients. The results show that there are severe local metabolic disturbances in both injured and uninjured skin. Most interesting is a sustained tissue acidosis, which is not detectable in systemic (blood) sampling. We also recorded considerable alterations in the glucose homeostasis locally in the skin, suggesting a cellular or mitochondrial dysfunction. In parallel, we noted increased tissue glycerol concentrations, which indicated appreciable trauma- induced lipolysis. We also examined serotonin kinetics in the same group of patients, as serotonin has been claimed to be a key mediator of the vasoplegia and permeability disturbances found in patients with burns. We have shown, for the first time in humans to our knowledge, that concentrations of serotonin in skin are increased tenfold, whereas blood and urine concentrations are just above normal. The findings support the need for local monitoring of substances with rapid local reabsorption, or degradation, or both. The results also indicate that serotonin may be important for the systemic response that characterises burn injuries. In the second half of the thesis we evaluated the effects of microdosing in skin on metabolism and blood flow of vasoactive, mainly stress-response-related, drugs by the microdialysis system. The objectives were to isolate the local effects of the drugs to enable a better understanding of the complex relation between metabolic effects and effects induced by changes in local blood flow. In the first of these two studies we showed that by giving noradrenaline and nitroglycerine into the skin of healthy subjects we induced anticipated changes in skin metabolism and blood flow. The results suggest that the model may be used to examine vascular and metabolic effects induced locally by vasoactive compounds. Data from the last study indicate that conventional pharmacodynamic models (E ) for time and dose max response modelling may be successfully used to measure the vascular and metabolic response in this microdosing model. We conclude that the microdialysis technique can be successfully used to monitor skin metabolism and isolate a mediator (serotonin) of the local skin response in burned patients. It was also feasible to develop a vascular model in skin based on microdialysis to deliver vasoactive substances locally to the skin of healthy volunteers. This model provided a framework in which the metabolic effects of hypoperfusion and reperfusion in skin tissues could be examined further. 1 List of original papers This thesis is based on the following studies, which will referred to in the text by their Roman numerals: I. Samuelsson A, Steinvall I, Sjöberg F. Microdialysis shows metabolic effects in skin during fluid resuscitation in burn-injured patients. Critical Care 2006; 10(6):R172. II. Samuelsson A, Abdiu A, Wackenfors A, Sjöberg F. Serotonin kinetics in patients with burn injuries: A comparison between the local and systemic responses measured by microdialysis – A pilot study. Burns 2008; 34: 617-622. III. Samuelsson A, Farnebo S, Magnusson B, Anderson C, Tesselaar E, Zettersten E, Sjöberg F. Critical Care implications of a new microdosing model administering vasoactive drugs (noradrenalin/nitro-glycerine) by microdialysis to human skin. Submitted. IV. Folkesson Tchou K, Samuelsson A, Tesselaar E, Dahlström B, Sjöberg F. Assessment of a microdialysis method using urea clearance as a marker of drug induced changes in dermal blood flow in healthy volunteers. Submitted. Reprints were made with the kind permission of the copyright holders. 2