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PAIN CONTROL An open learning programme for healthcare workers Nan Stalker THE OPEN LEARNING FOUNDATION RADCLIFFE MEDICAL PRESS
USING THIS WORKBOOK The workbook is divided into ‘Sessions‘, covering specific subjects. ¯ In the introduction to each learning pack there is a learner profile to help you assess your current knowledge of the subjects covered in each session. ¯ Each session has clear learning objectives. They indicate what you will be able to achieve or learn by completing that session. ¯ Each session has a summary to remind you of the key points of the subjects covered. ¯ Each session contains text, diagrams and learning activities that relate to the stated objectives. ¯ It is important to complete each activity, making your own notes and writing in answers in the space provided. Remember this is your own workbook—you are allowed to write on it. ¯ Now try an example activity.
This activity shows you what happens when cells work without oxygen. This really is a physical activity, so please only try it if you are fully fit. First, raise one arm straight up in the air above your head, and let the other hand rest by your side. Clench both fists tightly, and then open out your fingers wide. Repeat this at the rate of once or twice a second. Try to keep clenching both fists at the same rate. Keep going for about five minutes, and record what you observe.I
Stop and rest for a minute. Then try again, with the opposite arm raised this time. Again, record your observations.
¯ Suggested timings are given for each activity. These are only a guide. You may like to note how long it took you to complete this activity, as it may help in planning the time needed for working through the sessions. ¯ Time taken on activity ¯ Time management is important. While we recognise that people learn at different speeds, this pack is designed to take 20 study hours (your tutor will also advise you). You should allocate time during each week for study. ¯ Take some time now to identify likely periods that you can set aside for study during the week. ¯
At the end of the learning pack, there is a learning review to help you assess whether you have achieved the learning objectives. ACKNOWLEDGEMENTS Writer: Nan Stalker Reviewer: Gill Young Director of programmes: Leslie Mapp Programmes manager: Caroline Pelletier Production manager: Stephen Moulds, DSM Partnership The views expressed are those of the team members and do not necessarily reflect those of The Open Learning Foundation. The publishers have made all reasonable efforts to contact the holders of copyright material included in this publication. © 1999 Open Learning Foundation Radcliffe Medical Press Ltd 18 Marcham Road, Abingdon, Oxon 0X14 1AA All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owner. British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library. ISBN 1 85775 436 0 Typset by DSM Partnership, London SW18 Printed and bound by Hobbs the Printers, Totton, Hants. contents Introduction Learning Profile Session One: Neurones Session Two: The brain Session Three: The spinal cord Session Four: Voluntary and reflex action and the autonomic nervous system Session Five: The human experience of pain Session Six: Natural analgesic systems Session Seven: The development of chronic pain Session Eight: The pharmacology of pain control Session Nine: The practice of pain management Learning Review Further Reading Useful Web addresses related to pain Resources Section
INTRODUCTION This unit focuses primarily on the pharmacological aspects of pain and pain control. In Session One we revise the topic of neurones. We identify different types of neurone and discuss nerve impulses, neurotransmitters and types of nerve fibre ending. In Session Two we revise the topic of the structure and function of the brain. We look at the different parts of the brain, and discuss the membranes which cover the brain – the meninges – and the cerebrospinal fluid which protects the brain and the spinal cord. In Session Three we revise the topic of the structure and function of the spinal cord. We discuss the structure of the spinal cord, and consider peripheral, cranial, spinal and cervical nerves. In Session Four we revise the topic of voluntary and reflex action and the autonomic nervous system. We start by discussing the function of the central nervous system then discuss voluntary movement and reflex action. We also consider the two parts of the autonomic nervous system: the sympathetic nervous system and the parasympathetic nervous system. In Session Five we discuss the human experience of pain. We review the history of pain, distinguish between acute and chronic pain, and discuss the modulation of pain. In Session Six we look at the natural analgesic systems of the human body. We start by discussing the endogenous opioid systems of the body and their role in controlling pain. We then go on to consider how acupuncture draws upon these systems to control pain.We also discuss the issues of referred pain and projected or phantom pain. In Session Seven we look at the development of chronic pain. We start by looking at how different types of pain are transmitted: in particular, we look at the role played by peripheral sensitisation and hyperalgesia in transmitting chronic pain. We then consider the role of a range of chemical mediators in transmitting pain. Next, we look at drugs that relieve pain by sensitising the nociceptors. Finally, we consider the issue of central sensitisation to pain, and the problem of peripheral nerve damage. In Session Eight we look at the pharmacology of pain control. We start by defining the most important terms used in the session, then go on to discuss an important group of drugs – the non-steroidal anti-inflammatory drugs or NSAIDs. We consider the mechanisms of NSAIDs, their therapeutic uses and some of the side effects which can be associated with them. Next, we discuss the use of opioids: how they work, their pharmacological properties, their effects, their therapeutic use and the problems of tolerance, withdrawal and dependence. Finally, we consider the use of some other drugs to relieve pain. In Session Nine we look at the management of pain. We start by considering the World Health Organisation analgesic ladder of pain management, then look in more detail at the use of drugs in pain management, and consider the problems of drug dependence and what is known as ‘the pain habit’. Learning Profile Below is a list of learning statements for this unit. You can use it as a way of identifying your current knowledge and deciding how the unit can develop your learning. It is for your general guidance only. You will need to check each individual session in more detail to identify specific areas on which you need to focus. For each of the outcomes listed below, tick the box on the scale which most closely corresponds to your starting point. This will give you a profile of your learning in the areas covered in each session of this unit. The profile is repeated again at the end of this unit as a learning review, and you will be able to check the progress you have made by repeating it again then. Session One I can:
Session Two I can:
Session Three I can:
Session Four I can:
Session Five I can:
Session Six I can:
Session Seven I can:
Session Eight I can:
Session Nine I can:
SESSION ONE Neurones Introduction In
this session we revise the topic of neurones. We identify different types of
neurone, and discuss nerve impulses, neurotransmitters and types of nerve fibre
ending. Session
objectives When
you have completed this session you should be able to:
1:
Nervous tissue The nervous system is the system of communication between the various parts of the body. It can be compared to a simple telephone system in which the brain is comparable to the central switchboard, the spinal cord is comparable to the main cable and the nerves are comparable to the telephone wires, ending in receivers and dischargers of messages in the body tissue. It is a two-way system with messages being transmitted between the brain and the body tissue via the neural network. Like the skeletal and muscular systems, the nervous system is made up of a special tissue – the nervous tissue.
ALLOW 5 MINUTES Name
the two component parts of nervous tissue and identify the name given
collectively to the two parts. Commentary The
two component parts of the nervous tissue are nerve cells and nerve
fibres. Collectively, the cell and its fibres are called a neurone. The neurone is the unit on which the nervous system is built. Cells and fibres are bound together by a special type of connective tissue known as neuroglia – this binds them into a solid but very soft and delicate tissue.
ALLOW 5 MINUTES Each
cell has one long fibre and several short fibres. Name the long fibre and the
short fibres and in one or two sentences identify their function. Commentary The
long fibre is called the axon, and the short fibre is called the dendrite.
The axon carries impulses from a cell and at its ending passes the impulses on
to another nerve cell or dendrite, or to tissue. The dendrite picks up the
impulse or message and carries the impulse or message to a cell. Nerve
cells are grouped together to form grey matter. Grey matter is found at the
periphery of the brain, the centre of the spinal cord and in the ganglia. (A
ganglion is a small mass of isolated nerve cells.) Nerve
fibres are grouped together to form the white matter of the nervous system.
White matter is found at the centre of the brain, the periphery of the spinal
cord and in the nerves. A nerve is simply a bundle of nerve fibres bound together by connective tissue. Whiteness of a nerve fibre is due to its protective sheath, which makes a marked difference in colour of the tissue, readily obvious to the naked eye. The nerve sheath consists of two coats, an outer coat of connective tissue called neurilemma and a thick inner fatty sheath called the myelin sheath. This fatty sheath is interrupted at intervals and the outer neurilemma dips in and forms notches called Nodes of Ranvier.
ALLOW 5 MINUTES Identify
and explain the three main functions of the myelin sheath. Commentary The
three main functions of the myelin sheath are as follows.
The
nerve cell and its fibres are one living unit, and if the fibre is cut off from
the cell it will die, as it is the cell which contains the nucleus and the
protoplasms of the fibre. Conversely, if the cell and the portion of the fibre
attached to it remain alive, a new fibre can grow from the severed end provided
the neurilemma remains intact. It should be remembered that the fibre will not grow through fibrous scar tissue of a wound; it will, however, grow along an old nerve sheath. As a result, the nerve supply can be restored if a nerve is cut, though it will take time for the nerve fibre to grow, as these fibres, though often short, can be as much as a metre in length. It will, however, take much longer for the newly grown fibre to learn to function fully. If the nerve cell is destroyed by injury or disease the fibre will also die. If this happens, neither the cell nor the fibre can be replaced.
ALLOW
5 MINUTES ACTIVITY
4 // ALLOW 5 MINUTES Draw
and label a diagram of a neurone. Commentary Your diagram should be similar to that shown in Figure 1, below.
Figure
1: Diagram
of neurone (End of Sample Material)
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ACTIVITY
