Physiologic Effects of Tissue Heating Local superficial heating (infrared heat) is recom-mended in subacute conditions for reducing pain and inflammation through analgesic effects. Su-perficial heating produces lower tissue tempera-tures at the site of the pathology (injury) relative to the higher temperatures in the superficial tissues, resulting in analgesia. During the later stages of injury healing, a deeper heating effect is usually de-sirable; it can be achieved by using the diathermies or ultrasound. Heat dilates blood vessels, causing the patent capillaries to open up and increase circu-lation. The skin is supplied with sympathetic vaso-constrictor fibers that secrete norepinephrine at their endings (especially evident in feet, hands, lips, nose, and ears). At normal body temperature, the sympathetic vasoconstrictor nerves keep vascular anastomoses almost totally closed, but when the superficial tissue is heated, the number of sympa-thetic impulses is greatly reduced so that the anas-tomoses dilate and allow large quantities of blood to flow into the venous plexuses. This increases blood flow about twofold, which can promote heat loss from the body. 45
The hyperemia created by heat has a benefi-cial effect on injury. This is based on increases of blood flow and pooling of blood during the meta-bolic processes. Recent hematomas (blood clots) should never be treated with heat until resolution of bleeding is completed. Some athletic trainers have advocated never using heat during any therapeutic modality application. 53 ,65, 66 , 67
The rate of metabolism of tissues depends partly on temperature. The metabolic rate increases approximately 13% for each 1° C (1.8° F) increase in temperature. 53 A similar decrease in metabolism has been demonstrated when temperatures are low-ered.
A primary effect of local heating is an increase in the local metabolic rate with a resulting increase in the production of metabolites and additional heat. These two factors lead to an increased
intravascular hydrostatic pressure, causing arterio-lar vasodilation and increased capilarterio-lary blood flow. 134 However, increased hydrostatic pressure involves a tendency toward formation of edema, which may increase the time required for rehabilita-tion of a particular injury. Increased capillary blood flow is important with many types of injury in which mild or moderate inflammation occurs because it causes an increase in the supply of oxygen, antibod-ies, leukocytes, and other necessary nutrients and enzymes, along with an increased clearing of metab-olites. With higher heat intensities, vasodilation and increased blood flow will spread to remote areas, causing increased metabolism in the unheated area.
This is known as consensual heat vasodilation and may be useful in many conditions where local heating is contraindicated. 38
The application of heat can produce an anal-gesic effect, resulting in a reduction in the inten-sity of pain. The analgesic effect is the most
Clinical Decision-Making Exercise 4–4
On day 2 following an ankle sprain. the athletic trainer decides to put a patient in a cold whirlpool to have her do exercises. At this point in a rehabilitation program is this really the best course of action?
analgesia Loss of sensibility to pain.
inflammation A redness of the skin caused by capillary dilation.
hyperemia Presence of an increased amount of blood in part of the body.
metabolites Waste products of metabolism or catabolism.
nutrients Essential or nonessential food substances.
vasodilation Dilation of the blood vessels.
consensual heat vasodilation Vasodilation and increased blood flow will spread to remote areas, causing increased metabolism in the unheated area.
CHAPTER 4 Cryotherapy and Thermotherapy 79 frequent indication for its use. 134 Although the
mechanisms underlying this phenomenon are not well understood, it is related in some way to the gate control theory of pain modulation. Heat has been shown to reduce pain associated with delayed onset muscle soreness following a 30-minute treatment. 135
Heat is applied in musculoskeletal and neuro-muscular disorders, such as sprains, strains, artic-ular (joint-related) problems, and muscle spasms, which all describe various types of muscle pain. 38 Heat generally is considered to produce a relax-ation effect and a reduction in guarding in skeletal muscle. It also increases the elasticity and decr-eases the viscosity of connective tissue, which is an important consideration in postacute joint injuries or after long periods of immobilization.
This may also be important during a warm-up activity prior to exercise for increasing intramus-cular temperatures. 133 However, it has also been demonstrated that heat alone without stretching has little or no effect in improving flexibil-ity. 2 , 10 , 20 , 127 It appears that a deep heating treat-ment using ultrasound may be more effective for increasing range of motion than using a more superficial heating technique. 62
Many athletic trainers empirically believe that heat has little effect on the injury itself but serves
rather to facilitate further treatment by producing relaxation in these types of disorders. 38 This is accomplished by relieving pain, lessening hyperto-nicity of muscles, producing sedation (which decreases spasticity, tenderness, and spasm), and decreasing tightness in muscles and related structures.
Thermotherapy Treatment Techniques Heat is still used as a universal treatment for pain and discomfort. See Table 4–4 for a summary of uses of thermotherapy. Much of the benefit is derived from the treatment simply feeling good.
However, in the early stages after injury, heat causes increased capillary blood pressure and increased cellular permeability; this results in additional swelling or edema accumula-tion. 3 , 15 , 38 , 63 , 153 No patient with edema should be treated with any heat modality until the reasons for the edema are determined. It is in the best interest of the athletic trainer to use cryotherapy techniques
indication The reason to prescribe a remedy or procedure.
edema Excessive fluid in cells.
Indications
Subacute and chronic inflammatory conditions Subacute or chronic pain
Subacute edema removal Decreased ROM
Resolution of swelling Myofascial trigger points Muscle guarding Muscle spasm
Subacute muscle strain Subacute ligament sprain Subacute contusion Infection
Contraindications
Acute musculoskeletal conditions Impaired circulation
Peripheral vascular disease Skin anesthesia
Open wounds or skin conditions (cold whirlpools and contrast baths)
TABLE 4–4 Indications and Contraindications for Thermotherapy
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to reduce the edema before applying heat. Superfi-cial heat applications seem to feel more comfort-able for complaints of the neck, back, low back, and pelvic areas and may be most appropriate for the patient who exhibits some allergic response to cold applications. However, the tissues in these areas are absolutely no different from those in the extremities. Thus the same physiologic responses to the use of heat or cold will be elicited in all areas of the body.
Primary goals of thermotherapy include increased blood flow and increased muscle tempera-ture to stimulate analgesia, increased nutrition to the cellular level, reduction of edema, and removal of metabolites and other products of the inflamma-tory process.
Warm Whirlpool
Equipment Needed. ( Figure 4–10 )
1. Whirlpool: The whirlpool must be the cor-rect size for the body segment to be treated.
2. Towels: These are to be used for padding and drying off.
3. Chair
4. Padding: This is to be placed on the side of the whirlpool.
Treatment. The patient should be positioned comfortably, allowing the injured part to be immersed in the whirlpool. Direct flow should be 6–8 inches from the body segment. Temperature should be 98–110° F (37–45° C) for treatment of the arm and hand. For treatment of the leg, the tem-perature should be 98–104° F (37–40° C), and for full body treatment, the temperature should be 98–
102° F (37–39° C). Time of application should be 15–20 minutes.
Considerations. Patient positioning should allow for exercise of the injured part. The size of the body segment to be treated will determine whether an upper extremity, lower extremity, or full body whirlpool should be used.
Application. The temperature range of a warm whirlpool is 100–110° F (39–45° C). It is similar in setup to a cold whirlpool. The patient must be positioned in the whirlpool with appropri-ate padding provided for the patient’s comfort. The unit should be turned on after it has been ascer-tained that the GFI is functioning. The timer should be set for the amount of time desired, depending on the size of the body part to be treated (10–30 min-utes). Treatment time should be long enough to stimulate vasodilatation and reduce muscle spasm (approximately 20 minutes). Again, caution is indi-cated in the gravity-dependent position in subacute injuries. 119 If some pitting edema exists (i.e., finger pressure on the skin leaves an indentation), cold or contrast baths are better indicated. In addition to increased circulation and reduction of spasm, Figure 4–10 Warm whirlpool.
Clinical Decision-Making Exercise 4–5
The athletic trainer is treating a patient with a grade 2 MCL sprain. After the first week there is still considerable swelling on the medial side of the knee just below the joint line. He decides to use a contrast bath to take advantage of the “pumping action”
of vasoconstriction/vasodilation. Is this technique likely to be effective?
CHAPTER 4 Cryotherapy and Thermotherapy 81 benefits of the warm whirlpool include the
massag-ing and vibratmassag-ing effects of the water movement.
On removal of the body segment from the whirl-pool, it is necessary to review the skin surface and limb girth to see if the warm whirlpool increased swelling; this step is indicated even if the patient is past the subacute stage. After allowing the body segment to cool down, appropriate preventive strapping or padding can be placed on the body seg-ment. If the patient receives the treatment before exercising, it is recommended that he or she gently do range-of-motion exercises to reduce congestion and increase proprioception (sense of position) in all joints. If the patient is complaining of muscle soreness, it would be more appropriate to recom-mend swimming pool exercises. The whirlpool pro-vides a sedative effect. It is recommended that the patient shower or clean the body surface before using a whirlpool. Random access to the whirlpool is not warranted.
The warm whirlpool is an excellent postsurgical modality to increase systemic blood flow and mobi-lization of the affected body part. The appropriate-ness of whirlpool therapy needs to be addressed by the athletic trainer because it is the most commonly abused physical therapy modality. An example of this abuse is the practice of placing an individual in the whirlpool without taking the time to assess the
specific physiologic responses desired. However, it is an excellent adjunctive modality when used appro-priately in the clinical setting.
Whirlpools should be cleaned frequently to pre-vent bacterial growth. When a patient with any open or infected lesion uses the whirlpool, it must be drained and cleaned immediately. Cleaning should be done using both a disinfecting and antibacterial agent. Particular attention should be paid to cleaning the turbine by placing the intake valves in a bucket containing the disinfecting solution and turning the power on. Bacterial cultures should be monitored periodically from the tank, drain, and jets.
Commercial (Warm) Hydrocollator Packs Equipment Needed. ( Figure 4–11 )
1. Unit heat packs: These are canvas pouches of petroleum distillate. A ther-mostat maintains the high tempera-ture (170° F) and helps prevent burns.
Unit heat packs come in three sizes:
(1) regular size is 12 inch × 12 inch for most body segments; (2) double size is 24 inch × 24 inch for the back, low back, and buttocks; and (3) cervical is 6 inch
× 18 inch for the cervical spine. Packs are removed by tongs or scissor handles.
2. Towels: Regular bath towels and commer-cial double pad towels are required. Com-mercial double pad toweling has a pouch for pack placement and 1-inch thick tow-eling to be placed in cross fashion, tags
Figure 4–11 (a) Hydrocollator packs stored in tank. (b) Come in a variety of sizes.
(a) (b)
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on the edge of packs folded in, toweling overlapped on one side and four layers on the opposite side. Six layers equal 1 inch of toweling. Additional toweling may be needed depending on total body surface covered.
Treatment. Position six layers of toweling as shown in Figure 4-12 . Sufficient toweling should be provided to protect the patient from burns. Patient position should be comfortable. Treatment time should be 15–20 minutes.
Physiologic Responses.
Circulation is increased.
Muscle temperature is increased.
Tissue temperature is increased.
Spasms are relaxed.
Considerations. The size of the body segment to be treated should determine how many packs are needed. Patient comfort is always a consideration.
Time of application should be 15–20 minutes. Also, after use rewarming of the pack requires about 20 minutes. 59
Application. Appropriate toweling and posi-tioning of the patient is necessary for a comfort-able treatment. The moist heat pack tends to stim-ulate the circulatory response. Dry heat, as discussed in the infrared section, has a tendency to force blood away from the cutaneous capillary bed, thus increasing the possibility of a burn with the skin’s inability to dissipate heat. 131 The patient
must not be allowed to lie on the packs because this will increase the risk of burn. Also, it may force the silicate gel out through the seams of the fabric sleeves. If the patient cannot tolerate the weight of the moist heat pack, alternate methods can be used. For example, the patient can be placed lying on his or her side, with the majority of the weight of the hot pack on the side of the pack and the pack held in place by additional towels or sheets wrapped around the patient. The most com-mon indications are for muscular spasm, back pain, or as a preliminary treatment to other modal-ities. Hot packs have been shown to attenuate delayed onset muscle soreness 30 minutes after treatment. 135
Figure 4–12 Techniques of wrapping hydrocollator packs.
Clinical Decision-Making Exercise 4–6
A volleyball player has an acute strain of the erector spinae muscles in the low back.
The athletic trainer feels that using ice on the low back will cause the patient to be uncomfortable and perhaps induce muscle guarding in the injured muscle. Thus, the athletic trainer chooses to use a hot hydrocollator pack instead of an ice pack.
Is this the appropriate clinical decision?
CHAPTER 4 Cryotherapy and Thermotherapy 83 Paraffin Baths. A paraffin bath is a simple
and efficient, although somewhat messy, tech-nique for applying a fairly high degree of localized heat. Paraffin treatments provide six times the amount of heat available in water because the mineral oil in the paraffin lowers the melting point of the paraffin. The combination of paraffin and mineral oil has a low specific heat, which enhances the patient’s ability to tolerate heat from paraffin better than from water of the same temperature.
The risk of a burn with paraffin is substan-tial. The athletic trainer should weigh heavily the considerations between a paraffin bath and warm whirlpool bath in the athletic setting. The majority of paraffin baths are used for chronic arthritis in the hands and feet. If the patient has
paraffin bath A combined paraffin and mineral oil immersion commonly used on the hands and feet for distal temperature gains in blood flow and temperature.
a chronic hand or foot problem, the use of paraffin instead of water usually gives longer lasting pain relief.
Equipment Needed.
1. Paraffin bath ( Figure 4–13 ) 2. Plastic bags and paper towels 3. Towels
Treatment.
Dipping. The extremity should be dipped into the paraffin for a couple of seconds, then removed to allow the paraffin to harden slightly for a few sec-onds. This procedure is repeated until six layers have accumulated on the part to be treated.
Wrapping. The paraffin-coated extremity should be wrapped in a plastic bag with several layers of toweling around it to act as insulation (Figure 4–13).
Treatment time should be 20–30 minutes.
Physiologic Responses.
Tissue temperature increases.
Pain relief occurs.
Thermal hyperthermia occurs.
Considerations. Some units are equipped with thermostats that may elevate the temperature to 212° F, thus killing any bacteria that may grow in the paraffin. Otherwise the temperature should be set at 126° F.
If the paraffin becomes soiled, it should be dumped and replaced at no longer than 6-month intervals.
Figure 4–13 (a) Hand being dipped in paraffin bath. (b) After being dipped in paraffin, the hand should be wrapped in plastic bags and toweling.
(a) (b)
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Application. A paraffin bath purchased for the clinic should have a built-in thermostat. Before treatment, the patient’s body segment should be cleaned thoroughly with soap, water, and finally alcohol to remove any soap residue. This will pre-vent bacterial buildup in the bottom of the paraffin bath, which is an excellent medium for culture growth.
The mixture ratio of paraffin to mineral oil is 1 gallon of mineral oil to 2 pounds of paraffin. The mineral oil reduces the ambient temperature of the paraffin, which is 126° F (at which tempera-ture a burn could occur). It is important to build six layers of paraffin, with the first layer highest on the body segment and each successive layer lower than the previous one. This is important because when dipping the extremity in the paraf-fin, if the second layer of paraffin is allowed to get between the skin and the first layer of paraffin, the heat will not dissipate and the patient could be burned. Because heat is retained in the body and is also radiated from the paraffin, capillary dilation and blood supply in the treated segment increase.
The athletic trainer should place the patient in a
comfortable position and enclose the paraffin in paper towels, plastic bags, and toweling to main-tain the heat. Treatment is applied for approxi-mately 20–30 minutes. Removing the paraffin calls for extra care not to contaminate the used portion so that it does not affect the entire bath when it is returned.
Removal of paraffin involves removing towels, plastic bag, and paper towels, then using a tongue depressor to split the paraffin to allow easy removal. If the paraffin has not touched the floor, remove the paraffin cast over the open paraffin bath. It will dissolve on returning to the remaining liquid paraffin. Clean the body segment with soap and water. If a postsurgical patient is being treated, give a massage because the mineral oil will make the skin moist and supple. When cleaning the skin, the athletic trainer must examine the surface for burns or mottling.
A less safe but likely more effective technique for increasing tissue temperature is to immerse the body part in the paraffin bath. The treatment begins by repeatedly dipping the body part in the paraffin as described above until at least six layers have accumulated. Next the body part is placed in the paraffin for the remainder of the treatment time. The patient should be instructed not to move the body part to keep the paraffin from cracking and to avoid touching the bottom or sides of the paraffin unit.
The thermostat will raise the temperature of the paraffin to 212° F, destroy any bacteria, and main-tain a sterile contact medium. Paraffin baths require supervision to prevent contamination, but they do provide a special type of treatment that is well adapted to the patient with injuries of the hands and feet.
Fluidotherapy. Fluidotherapy is a unique, multifunctional physical medicine modal-ity. The fluidotherapy unit is a dry heat modality
fluidotherapy A modality of dry heat using a finely divided solid suspended in a stream of air with the properties of liquid.
Treatment Protocols: Paraffin Bath 1. Guide the body part into the paraffin,
making sure the patient does not contact the bottom of the cabinet or the heating coils.
2. After 2 or 3 seconds, remove the body part and keep it above the paraffin so that none of the paraffin drips onto the floor.
Reimmerse the body part, and repeat until the appropriate number of dips have been completed, or reimmerse for the duration of the treatment.
3. Set a timer for the appropriate treatment time and give the patient a signaling device.
Make sure the patient understands how to use the signaling device.
4. Check the patient’s response after the first 5 minutes by asking the patient how it feels. Recheck verbally about every 5 minutes.
CHAPTER 4 Cryotherapy and Thermotherapy 85 that uses a suspended air stream, which has the
properties of a liquid. Its therapeutic effectiveness in rehabilitation and healing is based on its ability to simultaneously apply heat, massage, sensory stimulation for desensitization, levitation, and pressure oscillations. Fluidotherapy is capable of significantly elevating superficial skin tempera-ture. 60 Unlike water, the dry, natural medium does not irritate the skin or produce thermal shocks. 152 This allows for much higher treatment tempera-tures than with aqueous or paraffin heat transfer.
The pressure oscillations may actually minimize edema, even at very high treatment temperatures.
Clinical success has been reported in treatment of pain, range of motion, wounds, acute injuries, swelling, and blood flow insufficiency. Fluidother-apy treatment of the hand at 115° F (46.2° C) results in a sixfold increase in blood flow and a fourfold increase in metabolic rates in a normal adult. These properties will increase blood flow, sedate, decrease blood pressure, and promote heal-ing by acceleratheal-ing biochemical reactions.
Counterirritation, through mechanoreceptor and thermoreceptor stimulation, reduces pain sensitivity, thus permitting high temperatures without painful heat sensations. Pronounced hyperthermia accelerates the chemical metabolic processes and stimulates the normal healing pro-cess. The high temperatures enhance tissue elastic-ity and reduce tissue viscoselastic-ity, which improves musculoskeletal mobility. Vascular responses are stimulated by long-lasting hyperthermia and pres-sure fluctuations, resulting in increased blood flow to the injured area.
Equipment Needed.
1. Choose the appropriate fluidotherapy unit ( Figure 4–14 ).
2. Toweling Treatment.
The patient must be positioned for comfort.
The patient should place the body segment to be treated (hand or foot) in the fluidotherapy unit.
Protective toweling must be placed at the unit interface and body segment.
Treatment time should be 15–20 minutes.
Figure 4–14 Fluidotherapy treatment units. (Photo courtesy of Fluidotherapy Corporation, 6113 Aletha Lane, Houston. TX77081.)
Treatment Protocols: Fluidotherapy 1. With the agitation off, open the sleeved
portion of the unit.
2. Instruct patient to insert body part into the cellulose particles, reminding her to tell you if the temperature is too hot.
3. Fasten the sleeve around the body part to prevent the cellulose particles from being blown out of the unit, and start the agitation.
4. Check the patient’s response verbally after about 5 minutes. Remind the patient to tell you if the heating sensation becomes uncomfortable.
Physiologic Responses.
Tissue temperature increases.
Pain relief occurs.
Thermal hyperthermia occurs.
Considerations.
Fluidotherapy unit must be kept clean.
All knobs must be returned to zero after treatment.
Application. The patient should be positioned comfortably. The treated body segment should be submerged in the medium before the unit is turned
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