Physical Agents In Rehab- Cryotherapy PDF

PHYSICAL AGENTS IN REHAB CRYOTHERAPY CRYOTHERAPY Learning outcomes The student should be able to: Describe the different methods of cooling Explain the factors that influence the magnitude of temperature reduction with ice application Explain the physiological effects of cryo...

PHYSICAL AGENTS IN REHAB CRYOTHERAPY CRYOTHERAPY Learning outcomes The student should be able to: Describe the different methods of cooling Explain the factors that influence the magnitude of temperature reduction with ice application Explain the physiological effects of cryotherapy  Explain the indications for cryotherapy Outline the procedures for application of ice therapy Demonstrate the safe and effective application of cryotherapy given a patient case CRYOTHERAPY Cryotherapy is the local or systemic application of cold for diagnostic or therapeutic purposes. Methods of Cooling Convective eg use of an electric fan Evaporative- The use of volatile fluids such as ethyl chloride and chlorofluoromethane Conductive cooling- eg ice packs, frozen gel packs, iced towels and ice cubes continued Conductive cooling is the most common method. Heat is conducted away from the tissues. The magnitude of the temperature change produced in the tissues depend on: The temperature difference between the object and the tissue The time of exposure The thermal conductivity of the area being cooled The type of cooling agent Vascular supply continued The temperature gradient The greater the gradient, the greater the tissue temperature reduction The duration of exposure Related to the depth of tissue The deeper the tissue, the longer the time required to reduce its temperature. Temperature of muscle at 4 cm can be lowered by 3.5 degrees with 30 minutes of ice pack. continued Thermal conductivity Tissues with high water content such as muscle have a better thermal conductivity than fat. The amount of fat may influence how much and how fast muscle can be cooled and returned to its original temperature. Muscle at 2 cm can show temp reduction of 2 deg C after 10 minutes if covered by 1 cm of fat. If fat layer is thicker, 30 minutes may be required Vascular supply Cooling enhanced in areas with poor blood supply as vasoconstriction reduces loss of  Type of cooling agent Ice packs produce greater temperature reduction compared to cold water baths and gel packs. Vapocoolant spray reduces skin temperature quickly to 15 degrees without change in deep tissue temp Physiological Effects Vascular Immediate vasoconstriction of cutaneous blood vessels with reduction of blood flow Due to reflex action and the effect of cold on smooth muscles. Vasoconstriction lasts for 10-30 mins Increased viscosity of blood Liberation of histamine-like substance occurs resulting in vasodilation when cold application is intense- 10 deg C (Hunting response). This follows initial vasoconstriction  Thus vasodilation follows vasoconstriction and lasts for 4-6 mins. This removes the H substance. Cycles of vasoconstriction and vasodilation occur at 15-30 min intervals Overall net effect is still reduction in temperature and circulation Physiological effects continued Metabolic effects Metabolic rate decreases with cooling. Less demand for oxygen and nutrients and less production of metabolic waste. Slow metabolic rate can contribute to retardation of the healing process. Inflammatory process may be modified Influenced by intensity and duration of cold application  continued Neural effects Reduction of conduction velocity of peripheral nerves (sensory and motor). Can occur to the point where nerves fail to conduct. Magnitude of change depends on the duration and degree of temperature change “A” fibers are blocked (at 12 degree C) before “C” fibers Gamma fibers are blocked before alpha fibers To block C fibers temp should be close to 0 degree Blocking of synaptic transmission also occurs at 15 degree celsius Contd. At temperatures near freezing-all sensory neuron activity ceases Sensations felt on application of cold are: cold painfully cold less cold burning numbness then anaesthesia  Longer application of cold (e.g. 20 mins) can decrease motor nerve conduction velocity Muscle performance can be affected. continued Effect on swelling Cold lessens the filtration rate of fluid into the interstitium due to the vasoconstriction Neuromuscular effects Direct cooling of muscle results in a decrease in discharge of muscle spindle afferents and decrease in gamma motor neuron activity through cutaneous stimulation. Spasticity reduction continued Long duration cold application (15-30 minutes) decreases muscle temperature, associated with decrease in muscle strength. Reduction in muscle blood flow and increase in viscous properties at 10 degrees Short duration application (1-2 mins) has facilitatory effect on alpha motor neuron continued Tissue damage Tissue damage may occur depending on the duration and intensity of cold application. First degree- Red, inflamed, mild oedema Second degree- Marked oedema, blisters Third degree- Necrosis, blue skin color, Fourth degree- gangrene and neurological complications Summary of Physiological Effects Decrease in circulation/vasoconsriction Decrease in formation of exudate Decrease in haemorrhage following trauma Decrease in spasm and spasticity Decrease in pain Decreased metabolism Decreased extensibility of tissue Increased blood viscosity Indications Reduction of acute pain slow nerve conduction velocity, counter- irritant Control of bleeding and swelling associated with acute trauma, sprains, strains vasoconstriction & increased blood viscosity Treatment of acute burns- reduce pain and blistering Reduction of spasm decrease nerve conduction velocity in muscle spindle afferents Indications continued Reduction of spasticity- Decreased nerve conduction velocity. Decrease firing of muscle spindle afferents. Cold may reduce spasticity for up to 90 mins. Egs. Stroke, SCI, UMNL Facilitation of motor responses In patients with neurological involvement or orthopaedic problems Decrease inflammation and pain associated with joint mobs, friction massage Contraindications/Precautions History of frostbite Impaired circulation Impaired sensation Very old or very young Sensitivity or allergy to cold Before exercises Before stretching Raynaud’s disease Allergic reaction to cold (cold urticaria) contd Open wounds Over regenerating peripheral nerves Dangers Cold intolerance- severe pain, redness, cyanosis, mottling Burns Hypertensive response Frostbite- erythema, blistering, gangrene Cold urticaria- allergic skin reaction  Applications/techniques Ice Towels Comfortably position patient Explain procedure Check contraindications Examine signs and symptoms Examine skin for cuts, bruises, use of liniments Check thermal and pain sensation Protect clothing and bed linen Test patient’s reaction to ice Apply oil to skin continued Warn patient about the different sensations Warn patient not to tolerate excessive burning Place ice flakes and cold water in a container Fold towel lengthwise and place in container Remove, wring and place on patient continued Change towels every minute Try to keep towels at same temperature (10-14 degrees) Total treatment time 10-15 mins Assess area and patient’s response continued Ice packs Same preparation as for ice towels Place ice chips in a moistened terry towel Chips can also be placed in sealed plastic bag Mold pack to area ensuring even contact Treat for 5-15 mins or 20-40 for deeper muscle For swelling- bandage ice pack to achieve compression and elevation (RICE) (ICER) continued Cryogel packs These are stored at temperature of -5 degrees Should be refrigerated at least 2 hours before use. Should be wrapped in towel and placed on patient’s skin Secure with a strap Treat for 10-15 mins Chemical cold packs A seal is broken which mixes and activates chemicals. Single use. Gel packs continued Ice immersion Same preparation as for ice packs Place part in container of water then place chips in container For pain and swelling- immerse part and withdraw when there is discomfort and wipe. Repeat up to 10 times For spasticity- Immerse and leave for as long as possible. Shivering and hypothermia could increase spasticity. Apply heat elsewhere to counteract Total body immersion for 5-7 mins also possible continued Ice massage Done for small localized area of pain and swelling Use ice cube or ice lolly Massage slowly with constant motion using firm pressure Do not allow any water to drip Patient will experience sensation of burning, aching, then numbness. Skin temp will not fall below 15 deg Treat for 5-10 mins Ice massage modalities continued Ice for stimulation/ facilitation Run ice quickly over muscle belly. 3-5 swipes Follow immediately by asking patient to contract muscle There should be no dripping Effect may be immediate or delayed (27-42 minutes) Used for neurological disorders eg. Stroke and peripheral nerve injuries continued Egs. To facilitate swallowing and speech –use quick icing over supra sternal notch To facilitate knee extensors- ice over belly of vastus medialis and lateralis To facilitate dorsiflexion- Ice over tibialis anterior To facilitate deep breathing- ice over trunk, T7- T12 Techniques continued Vapocoolant sprays Position so that part is exposed and eyes protected Hold bottle in an inverted position, 18 inches away from the skin and at a 30 degree angle Spray entire length of muscle at a rate of 4 inches per second, with muscle in stretched position. Repeat Spraying should not exceed 6 seconds, to avoid frostbite Caution: Ethyl chloride spray bottle could Vapocoolant sprays contd Cryocuff Applies cold and compression together Cuff, cooler and tube Applied to shld, knee, foot, ankle, thigh and calf 1 inch of elevation= 1.8mmHg pressure Choice of agent This depends on 1.Effects desired Facilitation- quick icing Oedema control- ice pack, cryocuff 2.Accessibility of body part 3. Size of area to be cooled Foot - immersion Knee - packs, cryocuff Ankle - pack, immersion, cryocuff