Chapter 9 Heat and cold application

INTRODUCTION

Both cold and heat can be effective forms of treatment, for example to manage pain, stiffness, oedema and spasticity. Chapter 7 describes in some detail the physical and physiological changes that can arise in the human body due to thermal variation. This chapter discusses the use of agents that effect temperature changes through direct physical contact with tissue and through radiation.

COLD OR HEAT?

Many, although not all, of the clinical benefits produced by heat and cold are similar. Selection is therefore sometimes based on a number of factors that might, on occasion, be empirical but are nevertheless important.

• Stage of inflammation. Generally, cold is preferable during the acute stage of inflammation to relieve pain, reduce the level of bleeding and swelling (these benefits are especially effective if applied early and, in practice, often combined with compression) and possibly retard secondary injury following trauma (see Chapter 4). Heat, in contrast, can exacerbate the early inflammatory process.

• Oedema (swelling). Heat tends to increase oedema whereas cold can help to limit it in recent injuries (see above).

• Collagen extensibility. A rise in temperature increases collagen extensibility, whereas it becomes stiffer with cold.

• Pain. Both heat and cold can be used to relieve pain. The effect of cold may be more prolonged but in certain situations can cause/increase pain.

• Spasm. Both heat and cold can decrease muscle spasm associated with musculoskeletal injuries and nerve root irritation. Similarly, both will reduce spasticity due to upper motor neuron dysfunction, though heat will do so for only a short period of time; cold is generally more effective under these circumstances as the return to normal temperatures takes longer.

• Muscle contraction. There appears to be a slight increase in the power of contraction with a rise in temperature within normal temperature ranges (approximately 25–37°C), especially in type 1 muscles, whereas cooling below this leads to a decrease.

• Area to be treated. In some subjects (e.g. those with Raynaud’s disease) the application of cold to the hands and feet leads to severe pain, and this may therefore be an indication for heat therapy.

• Ease of use. This can be especially important when considering home therapy administered by the patient.

• Patient preference. Some subjects find cold intolerable; the use of heat to relieve both pain and muscle spasm may be more acceptable.

• Specific contraindications to either heat or cold.

WET OR DRY?

A second important factor to be considered when selecting thermal treatments is that of choosing between wet and dry contact techniques. Little is known about the relative efficacy of one compared with the other; however, Abramson (1967) has suggested that dry heat can elevate surface temperature to a slightly greater degree, whereas wet heat can lead to rises in temperature at slightly deeper levels. Thus either can be used for closed injuries, with choice largely dependent on pragmatic considerations. Wet techniques have the potential to introduce infection into an open wound and to waterlog tissue. Drying, for example with infrared heating, can be detrimental to wound repair but has been demonstrated to be effective in the management of some skin conditions.

COLD AND HEAT

The effects of cold, contact heating methods and infrared irradiation are described separately in the following sections. However, occasionally cold and heat can be used alternately, most commonly in contrast baths. These comprise two water baths at different temperatures: a hotter bath at 40–42°C (immersion for 3–4 minutes) and a colder one at 15–20°C (immersion for about 1 minute). The body part is placed in each bath alternately, and it is normal practice to begin and end with the hotter bath. Lehmann and de Lateur (1990) have suggested that a 10-minute immersion in the warmer bath prior to the use of the colder contrasting temperature may be useful in producing an initial hyperaemia.

Few studies have examined the efficacy of this treatment but it is suggested that hyperaemia, reduced oedema due to vasodilation (Woodmansey et al 1938) and pain relief – possibly through the pain gate mechanism – may be implicated (Lehmann & de Lateur 1999). Myrer et al (1994) demonstrated that contrast baths are unlikely to result in an increase in intramuscular temperature.

CRYOTHERAPY (THERAPeUTIC COLD)

Tissues can be cooled for therapeutic reasons. The changes in temperature that can be achieved have been reported in many studies and vary enormously. This variation can be attributed to:

• different methods of application

• the length of time over which cooling has been applied

• the initial temperature of the technique used, e.g. water temperature.

THE EFFECTS ON TISSUES

Intramuscular temperature

The associated drop in temperature depends on the duration of the treatment, the depth of the muscle from the surface, the thickness of adipose tissue that insulates the underlying muscle and the initial temperature of the treatment agent; cooling persists for several hours (Meussen & Lievens 1986). Using a crushed ice bag, Otte et al (2002) reported drops in temperature of around 7°C at a depth of 1cm in muscle in a patient with a skin fold of 20mm in approximately 25 minutes; however, it took around 40 minutes to achieve this drop when the skin fold was between 21 and 30mm.

Joint temperature

This appears to remain low after the application of cold, although some investigators have reported an initial brief rise in temperature (Kern et al 1984). Given the above report of limited cooling of muscle when insulated by adipose tissue, it is important to note that joint cooling will be very limited in most, especially deeper, joints.

PHYSIOLOGICAL EFFECTS

These are described in detail in Chapter 7 and include effects on cell function in general, circulation (reduced blood flow, oedema, haemorrhaging), collagen, neurological tissue (pain, spasm), muscle (contraction rates and power) and tissue repair. It is important to remember that contact methods of cooling produce only relatively superficial changes, so effects will be very limited in the deeper tissues of the body.

CLINICAL EFFICACY

Studies examining clinical efficacy support the empirical evidence for the use of ice for a number of symptoms. Cooling can reduce swelling following injury (e.g. Basur et al 1976), and Hecht et al (1983) demonstrated that 10 treatments can reduce swelling in patients with osteoarthritis (OA) of the knee. However, in clinical practice, cooling is often accompanied by compression or other treatments, which means that it is often difficult to ascribe the benefits to cooling alone.

Pain is normally reduced by cooling, mediated by the neurological effects described in Chapter 6. Examples include patients with OA of the knee (Clarke 1974) and following arthroscopy (Lessard et al 1997), and (Curkovic et al 1993) demonstrated an elevation of the pain threshold in patients with rheumatoid arthritis immediately after treatment; this declined within 30 minutes. Pain may be due to tissue irritants; a number of studies have suggested that patients with arthritis may experience pain relief owing to the adverse effects of cooling on the activity of destructive enzymes within the joints (Harris & McCroskery 1974, Pegg et al 1969).

The report by Lessard et al (1997) demonstrates a significant difference between the postarthroscopy groups (exercise regimen plus cold, or exercise regimen only) in terms of increased compliance and weight bearing. Effects on muscle performance are described in Chapter 7 and clinical studies lend some support to these findings (e.g. Oliver et al 1979): there is some evidence that it improves above pretreatment levels during the hours following cooling. Yurtkurtan and Kocagil (1999) demonstrated increased quadriceps strength, range of movement of the knee and timed walking in patients with OA.

Finally, cooling recently injured tissues may confer some protection against secondary damage of adjacent cells due to hypoxia and enzyme activity by lowering the metabolic demands of the cells (see Chapter 7 for further discussion). Although this indicates good effects from cooling, it is important to note that clinical scenarios are complex and attributing effects exclusive to cooling can be difficult.

METHODS OF APPLICATION

Cold can be applied in a number of ways. These include the more common contact methods employing conduction (see Chapter 2 for details), such as wet and dry packs, and baths. In addition, evaporating sprays, relying on evaporation for their effect, may be used. During the application of cold therapy the subject will experience a number of sensations; these may include:

• intense cold

• a ‘burning’ sensation

• aching

• analgesia.

Before any application, the body part shouldbe inspected for any contraindications and an explanation and safety warnings given (see the next section).

Cold packs

Cold packs can be either ‘homemade’ by the clinician or purchased. Satisfactory packs can be made by wrapping flaked ice in damp terry towels. These can be applied to the body part to be treated for anything up to 20 minutes. The rate of initial cooling is rapid but decreases as a film of water forms between the pack and the skin; this means that the temperature of the skin is usually above that of the melting ice and is generally in the region of 5–10°C.

Cold packs produced commercially are of two types. First, bags that contain a mixture of water and an antifreeze substance are available, and are cooled in a freezer. Care should be taken on initial application as the temperature of the pack can be below 0°C and can therefore cause very rapid cooling of the surface tissue and possible injury. A damp towel placed between the skin and the pack can ensure that the contact temperature remains a little above 0°C. Second, packs that rely on a chemical reaction for their cooling properties are available. Such packs may be used only once. Although both types of pack are effective in reducing tissue temperatures, McMaster et al (1978) demonstrated that chemical packs are more effective in lowering subcutaneous temperatures. However, as suggested earlier in this section, the final temperature developed depends on a variety of factors.

Very superficial cooling may be achieved through the use of ice towels and gels. Towelling may be placed in a mush of flaked ice and water, wrung out and applied to the part. Large areas may be covered, but the towel will need to be replaced frequently as it warms up rapidly. Treatment may be given for up to 20 minutes.

Application

Some form of barrier is normally placed between the skin and cooling medium to prevent damage; this may be a damp towel which ensures the temperature is above 0°C or a barrier cream to prevent adhesion between the skin and agent; neither is needed with gels or sprays. The part should be observed regularly during treatment to avoid cold burns.

Cold baths

One of the simplest methods of cooling tissue is to place the body part in cold water or a mixture of ice and water. The temperature can be controlled by varying the ratio of ice to water. Lee et al (1978) suggest that a temperature of 16–18°C may be tolerated for 15–20 minutes. Lower temperatures may be used but will require intermittent immersion of the part. Clinical and experimental studies have used a wide variety of temperatures depending on the aim of the work.

Vaporizing sprays

Chapter 2 discusses the role of evaporation in producing cooling of the skin. Techniques that use this method of reducing skin temperature result in effective but short-lived tissue cooling. As yet unpublished work suggests that rewarming begins at about 15–20 seconds after the preceding application, and that statistically significant decreases in temperature to around 15–20°C can be produced with repeated applications (Cocker 2004, Collier 2004, Griffin 1997).

Application

A volatile liquid (e.g. dimethyl ether) is sprayed directly on to the area to be treated. For safety reasons, it is important that the spray is both non-flammable and non-toxic. It should be applied over the area in a number of short bursts (of approximately 3–5 seconds each). Generally, three to five bursts are adequate.

Ice massage

Ice massage can be used to produce analgesia. The technique, which uses ice ‘lollipops’ or blocks, is normally performed over a small area such as a muscle belly or trigger point, and may be used prior to other techniques such as deep massage. Waylonis (1967) discusses the physiological effects of ice massage and suggests that an area of up to 10–15cm² may be treated for up to 10 minutes or until analgesia occurs. A slow, circular motion over a small area is used. Temperatures do not drop to levels below 15°C with this method. Ice massage may also be used to facilitate muscle activity. In this case, ice is applied briskly and briefly over the skin dermatome of the same nerve root as the muscle in question. A number of studies have looked again at this area. Melzack et al (1980) reported that ice massage and transcutaneous electrical stimulation reduced pain to a similar degree; Roberts et al (1992) that it was more effective than both heat and cold packs; Yurtkurtan & Kocagil (1999), in a randomized controlled trial, showed improvements in a variety of outcomes in subjects with OA (see above). All suggest that ice massage has an effect on pain.

Only gold members can continue reading. Log In or Register to continue