Theories, evaluation and management
Silvia Paz and Jane Seymour
It is only during the last 50 years that pain has been recognized as a condition that requires specialized treatment and dedicated research. Before the availability of analgesics and anaesthetics, pain was regarded as a natural and an expected part of life, and was explained primarily in terms of a religious belief system within which medicine had little part to play. During the nineteenth century, with the emergence of 'modern' medical and scientific ideas, advances in anatomy, physiology, chemistry and pharmacy heralded the discovery of analgesics and anaesthetics, together with techniques for their application. As a result, medical and research interest in the subject was generated, and by the beginning of the twentieth century physicians engaged not only in controlling pain but also in finding a scientific explanation for it. Until the 1960s, pain was considered by most clinicians as an inevitable sensory and physiological response to tissue damage: there was little recognition or understanding of the effects on pain perception of individual expectations, anxiety, past experience or genetic differences. Moreover, no distinction was made between 'acute' and 'chronic' pain states. It is only in more recent years that the physiological, psychological and socio-cultural factors that contribute to the perception of pain have begun to be understood, and the necessary differentiation made in treatments of acute and chronic pain. The aims of this chapter are to: provide a framework for understanding theories of pain and pain mechanisms, and how these have developed over time; describe basic principles for the management of chronic and cancer pain; and examine the role of the nurse in the assessment and measurement of pain, and in the administration of analgesics.
Pain is difficult to define because of the complexity of its anatomical and physiological foundations, the individuality of its experience, and its social