Many patients with chronic pain use some form of heat application in the home environment and frequently wish to continue using these heat therapies admitted to hospital. This article provides an overview of the use of heat therapy with patients in the hospital setting and identifies some of the safety issues involved.
Chandler A et al (2002) Using heat therapy for pain management. Nursing Standard. 17, 9, 40-42. Date of acceptance: August 29 2002.
SUPERFICIAL HEAT therapy has been used for decades to relieve muscular and joint pain, including arthritis, back pain and dysmenorrhoea. Scientific evidence for the analgesic effectiveness of heat therapy is limited, and this is due in part to the lack of well-designed research studies (Robinson et al 2002). Interestingly, two recent randomised studies investigating the effect of topical heat therapy for the treatment of dysmenorrhoea and acute low back pain have shown it to be effective when compared with simple drug treatments such as ibuprofen and paracetamol (Akin et al 2001, Nadler et al 2002). In both studies, heat was applied by an air-activated heat wrap, which is currently only available in the United States.
Despite the limited scientific evidence for the analgesic effectiveness of heat therapy, there is much anecdotal evidence to support its usefulness in relieving pain, either alone or as an adjunct to other pain treatments. As a result, many nurse clinicians support its use at home and in the healthcare setting (Carr and Mann 2000, Foyle 2000, McCaffery and Wolff 1992).
Heat stimulates the thermoreceptors in the skin and deeper tissues. This can help to reduce pain according to the gate control theory (Melzack and Wall 1965). The theory proposes that within the spinal cord there is a pain gating mechanism that modulates pain transmission. Painful impulses carried into the spinal cord via the small diameter sensory fibres open the gate to allow pain signals to be transmitted to the brain. In contrast, impulses carried via larger diameter sensory fibres which respond to warmth, coolness, massage and transcutaneous electrical nerve stimulation help to close the gate, therefore modulating the transmission of painful impulses and leading to a reduction in pain.
Superficial heat relieves pain in a number of different ways:
* Heat stimulates the thermoreceptors in the skin and deeper tissues. This can help to reduce pain by closing the gating system in the spinal cord (Carr and Mann 2000).
* Heat reduces striated muscle spasm by minimising muscle spindle excitability and reducing tension in muscle trigger points (McCaffery and Wolff 1992).
* By warming joints, heat reduces the viscosity of synovial fluid, which alleviates painful stiffness during movement and increases joint range (Carr and Mann 2000).
Heat therapy in the clinical setting
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