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Thermal Agents: Cold and Heat

Thermal Agents: Cold and Heat. Physical Principles of Thermal Transfer. Specific Heat Specific heat is the amount of energy required to raise the temperature of a give weight of a material by a given number of degrees (F or C)

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Thermal Agents: Cold and Heat

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  1. Thermal Agents: Cold and Heat

  2. Physical Principles of Thermal Transfer • Specific Heat • Specific heat is the amount of energy required to raise the temperature of a give weight of a material by a given number of degrees (F or C) • Materials with a high specific heat hold more energy than materials with a low specific heat • Agents with higher specific heat are applied at lower temperatures • Ex – Paraffin bath is applied at lower temperature than hot pack

  3. Physical Principles of Thermal Transfer • Modes of Heat Transfer • Conduction: Heat Transfer by Direct Contact Such as Hot Packs and Cold Packs • Rate of Heat Transfer by Conduction • [(contact area) x (thermal conductivity) x (temp difference)] / tissue thickness • Thermal conductivity = rate at which a material transfers heat

  4. Physical Principles of Thermal Transfer • Modes of Heat Transfer • Guidelines for Heat Transfer by Conduction • The greater the temperature difference, the faster the rate of heat transfer • Materials with higher thermal conductivity transfer heat more rapidly than those with lower thermal conductivity • The larger the area of contact, the greater the total heat transfer • The thicker the tissue, the slower the rate of heat transfer

  5. Physical Principles of Thermal Transfer • Modes of Heat Transfer • Convection: Heat Transfer by Circulation of a Medium of a Different Temperature Such as Fluidotherapy, Whirlpool, Blood Circulation • Convection – heat transfer due to direct contact between a circulating medium and another material of a different temperature

  6. Physical Principles of Thermal Transfer • Modes of Heat Transfer • Conversion: Conversion from One Type of Energy to Another Such as Ultrasound Diathermy, and Metabolism • Conversion of a non-thermal form of energy (physical/mechanical, electrical, or chemical) to a thermal form of energy

  7. Physical Principles of Thermal Transfer • Modes of Heat Transfer • Radiation: Exchange of Energy Directly without an Intervening Medium Such as Infrared Lamp • Radiation – transfer of energy without direct contact

  8. Physical Principles of Thermal Transfer • Modes of Heat Transfer • Evaporation: Absorption of Energy as the Result of Conversion of a Material from a Liquid to a Vapor State Such as Vapocoolant Sprays • During evaporation, energy is absorbed when a solid is converted to a liquid or a liquid is converted to a gas/vapor (sweating) • Vapocoolant sprays result in cooling of an area due to evaporation

  9. Vapocoolant Spray

  10. Cold- Cryotherapy • Hemodynamic Effects • Initial Decrease in Blood Flow

  11. Cold- Cryotherapy • Hemodynamic Effects • Initial Decrease in Blood Flow • Later Increase in Blood Flow • Ice bath results • Cold-induce vasodilatation • Hunting response

  12. Cold- Cryotherapy • Neuromuscular Effects • Decreased Nerve Conduction Velocity • As temperature decreases, nerve conduction velocity decreases

  13. Cold- Cryotherapy • Neuromuscular Effects • Increased Pain Threshold • Gate Control Theory • Cold increases activity of the non-nociceptive fibers causing inhibition of nociceptive fibers

  14. Cold- Cryotherapy • Neuromuscular Effects • Altered Muscle Strength • Short cooling can result in increased strength • Long cooling can result in decreased strength

  15. Cold- Cryotherapy • Neuromuscular Effects • Decreased Spasticity • Decrease in motor neuron & muscle spindle activity • Facilitation of Muscle Contraction • Facilitates motor neuron activity by stimulating cutaneous sensory receptors • Lasts for only a short period of times (seconds)

  16. Cold- Cryotherapy • Metabolic Effects • Decreased Metabolic Rate • “Slows” or controls inflammation • Can slow healing • Cryotherapy is used for management of inflammatory diseases such as OA and RA

  17. Cold- Cryotherapy • Uses of Cryotherapy • Inflammation Control • Slows metabolism • Reduces edema • Reduces pain

  18. Cold- Cryotherapy • Uses of Cryotherapy • Edema Control • Due to vasoconstriction

  19. Cold- Cryotherapy • Uses of Cryotherapy • Pain Control • Gate Control Theory - Cold increases activity of the cutaneous thermal receptors (non-nociceptive fibers) causing inhibition of nociceptive fibers

  20. Cold- Cryotherapy • Uses of Cryotherapy • Modification of Spasticity • Decrease in reflexes • Duration - 5 – 30 mins • 30 mins for severe spasticity

  21. Cold- Cryotherapy • Uses of Cryotherapy • Facilitation • Quick icing may be used to elicit desired motor patterns

  22. Cold- Cryotherapy • Uses of Cryotherapy • Cryokinetics and Cryostretch • Cryotherapy is used to minimize sensation (numbness) prior to exercise/stretching to decrease pain perception

  23. Cold-Cryotherapy • Contraindications for Cryotherapy • Cold Hypersensitivity • Elevated patches which are red or pale • Cold Intolerance • Cryoglobulinemia – aggregation of serum proteins limiting circulation • Associated w/ lupus & RA

  24. Cold Hypersensitivity

  25. Cold-Cryotherapy • Contraindications for Cryotherapy • Raynaud’s Disease/Phenomenon • Sudden pallor & cyanosis followed by redness (mainly seen in the distal extremities) • Over Regenerating Peripheral Nerves • Over an Area With Circulatory Compromise or Peripheral Vascular Disease

  26. Raynaud’s Disease/Phenomenon

  27. Cold-Cryotherapy • Precautions for Cryotherapy • Apply Cryotherapy with Caution: • Over a Superficial Main Branch of a Nerve • Over an Open Wound • When Treating Patients with Hypertension • When Treating Patients with Poor Sensation or Mentation • When Treating Very Young and Very Old Patients

  28. Cold-Cryotherapy • Adverse Effects of Cryotherapy • Tissue Death • Frostbite • Nerve Damage • Unwanted Vasodilatation

  29. Cold-Cryotherapy • Application Techniques • Sequence of Sensations in Response To Cryotherapy • Intense Cold • Burning • Aching • Analgesia and numbness

  30. Heat-Thermotherapy • Effects of Heat • Hemodynamic Effects • Vasodilatation

  31. Heat-Thermotherapy • Effects of Heat • Neuromuscular Effects • Changes in Nerve Conduction Velocity and Firing Rate

  32. Heat-Thermotherapy • Effects of Heat • Neuromuscular Effects • Increased Pain Threshold

  33. Heat-Thermotherapy • Effects of Heat • Neuromuscular Effects • Changes in Muscle Strength

  34. Heat-Thermotherapy • Effects of Heat • Metabolic Effects • Increased Metabolic Rate

  35. Heat-Thermotherapy • Effects of Heat • Altered TissueExtensibility • Increased Collagen Extensibility

  36. Heat-Thermotherapy • Uses of Superficial Heat • Pain Control

  37. Heat-Thermotherapy • Uses of Superficial Heat • Increased ROM and Decreased Joint Stiffness

  38. Heat-Thermotherapy • Uses of Superficial Heat • Accelerated Healing

  39. Heat-Thermotherapy • Uses of Superficial Heat • Infrared Radiation for Psoriasis and Dermal Ulcers

  40. Heat-Thermotherapy • Contraindications for the Use of Thermotherapy • Acute Injury or inflammation • Recent or Potential Hemorrhage • Thrombophlebitis

  41. Heat-Thermotherapy • Contraindications for the Use of Thermotherapy • Impaired Sensation • Impaired Mentation • Malignancy • Infrared Irradiation of the Eyes

  42. Precautions for the Use of Thermotherapy Pregnancy Impaired Circulation Poor Thermal Regulation Edema Heat-Thermotherapy

  43. Precautions for the Use of Thermotherapy Cardiac Insufficiency Metal in the Area Over an Open Wound Over Areas Where Topical Counterirritants Have Recently Been Applied Heat-Thermotherapy

  44. Adverse Effects Of Thermotherapy Burns Fainting Bleeding Skin and Eye Damage from IR Radiation Heat-Thermotherapy

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