Physiological Considerations for Compression Bandaging. Harvey N. Mayrovitz, Ph.D.

Transcription

1 Physiological Considerations for Compression Bandaging Harvey N. Mayrovitz, Ph.D.

2 Objectives Therapeutic Compression Principles and Definitions Physiological Effects Mechanisms of Action Differential Features Some New Thoughts

3 Relationship to Wound Healing Impediments to Healing Blood Flow Oxygenation Infection Tissue Environment Deficit Origins Arterial Venous Microvascular Lymphatic Localized Edema/Lymphedema Compression Therapy

4 Circulation Schema O 2 CO 2 Capillary H 2 O Vein Lymphatics Arterioles Artery

5 Normal Fluid Balance Resorption Blood Capillary Filtration Π = 25 mmhg P A 35 mmhg 15 P V ~27 liters/day ~30 liters/day ~3 liters/day (10% of filtered) protein Lymphatic Capillary

6 Increased Venous Pressure or Capillary Permeability Resorption Blood Capillary Filtration P A 35 mmhg 20 P V Less Resorption More Filtration Lymphatic Capillary

7 If Net Filtration Exceeds Lymphatic Transport Capacity Overload = Edema + [Protein] = Lymphedema Therapy Options Reduce Filtration Increase Transport

8 Normal Lymph Transport Lymphangion Contraction Skeletal Muscle Pump Arterial Pulsations Body Movements Respiration All are Dynamic Processes

9 Lymphatic Capillaries Lumen Lymphatic Capillary P L P L > P T EC Anchoring Filaments P T Blood Capillary

10 Lymphatic Capillaries Lumen Lymphatic Capillary P L P L > P T EC Anchoring Filaments P T Blood Capillary Lumen EC P L +P T P L < P T

11 Lymphatic Hearts Peristaltic-like contractions propel lymph to next segment Lymph Capillary Lymphangion (lymph micro heart) Walls have a muscular media Valve

12 Lymphatic Hearts Lymph Capillary Lymphangion Contraction force is preload and afterload dependent - analogous to heart

13 Relationship to Wound Healing Impediments to Healing Blood Flow Oxygenation Infection Tissue Environment Deficit Origins Arterial Venous Microvascular Lymphatic Localized Edema/Lymphedema Compression Therapy

14 Calf Muscle Pump and Normal Valves Relaxed Contracted Superficial Deep Superficial Deep Skin Fascia Skin Fascia

15 Calf Muscle Pump and Valve Dysfunction Veins Distended Relaxed Contracted Resting Venous Pressure INCREASED High pressure transmitted to Superficial Veins Pump Efficiency Reduced

16 Venous Valve Dysfunction Chronic venous hypertension due to Chronic venous insufficiency (CVI) predisposes to developing venous ulcers Increased Ambulatory Pressure Significant insufficiency Moderate insufficiency Normal Volume Venous Reflux Emptying by exercise Time (seconds)

17 Venous Valve Dysfunction Chronic venous hypertension due to Chronic venous insufficiency (CVI) predisposes to developing venous ulcers Increased Ambulatory Venous Pressure Venous Pressure Resting CVI Normal

18 External External Compression Compression Tissue Tissue Pressure Pressure Vein Vein Diameter Trans Trans-locate locate Volume Volume Venous Venous Pressure Pressure Diameter Arteriolar Arteriolar Vasodilation Vasodilation Velocity Velocity Shear Shear Stress Stress Nitric Oxide Promote Promote Fluid Fluid Absorption Absorption Normalize Normalize Permeability Permeability WBC WBC Adherence Adherence

19 Compressive Pressure Effects External P e P e P e P i P i Transmural Pressure P TM = P i -P e

20 Differential Pressure Effects P e 5 P e 40 P e 40 Arteriole Thickness Structure P i 45 P i 45 Active Dilation P e 5 P e 40 P e 40 Venule P i 15 P i Passive Compression

21 Compression Therapy Considerations

22 Types of Compression Bandage Bandage-like Pumps Stockings Short-Stretch Stretch Long -Stretch Short-Stretch Stretch Dynamic Prevention Maintenance

23 Arrangement Superficial Drains Skin and Subcutis Skin Facia Deep Vascular Sheath Muscle Bone

24 Vascular Sheath L L V A V Arterial Pulsations Can Mechanically Augment Lymph Transport

25 Arterial Flow Pulses Below Knee Blood Flow via Nuclear Magnetic Resonance ml/min Control Leg Treated Leg Before Bandage ml/min With Bandage Increased pulses likely augment Lymph/venous transport

26 Compartments Tibia Anterior Tibial Anterior Greater Saphenous Fibula Lateral Deep Posterior Posterior Tibial Superficial Posterior Peroneal Skin Lesser Saphenous Want Therapy to Affect Superficial and Deep

27 Pressures of Interest Tibialis m. Tibia 1 Sub-bandagebandage Surface Contact 2 Fibula Peroneus Tissue Interstitial Popliteus m. Tibialis m. Soleus m. Gastroc m. 3 Compression Bandage or Device Skin Intramuscular

28 Edema and Tissue Pressure Normal P T P T Loose Fibrous Trabeculae

29 Resting (Static) Pressure Muscles Relaxed Pressure due to bandage tension (T) projecting an inward radial pressure (P) T R Compression Bandage or Device Laplace s Law P ~ T R Superficial vessels affected the most

30 Pressure Gradient Concept Compression Applied at Constant Tension P ~ T R Increasing R Decreasing P Mimics Normal Intravascular Pressure Gradient

31 Working (Dynamic) Pressure Contracted Muscles Positive affect on deeper vessels P Bandage acts as a restraint to muscle expansion Pressure is developed from within P ~ Contraction Force x Rigidity

32 Dynamic Pressure Depends on Bandage Material Features Dynamic Pressure ( P) 0 Form fitted steel pipe short stretch long stretch Bandage Stretchibility No external compression

33 Bandage Features Effect Pressure Working Pressure Stiffer = More Pressure Volume Change Stiffer = Less Expansion P Elasticity ( Strechibility )

34 Working vs. Resting Pressures Role of Compression Material Tissue Pressure (P T ) Emptying Resting Filling Filling Short Stretch Long Stretch Time

35 Overall Impact of Compression Depends on both working and resting pressures P U Upstream Pressure A Vein or Lymphatic Tissue Pressure P T Filling: Inflow ~ P U -P T Emptying: Outflow ~ V ~ P T Best: Adequate resting P T and High P T

36 Examples

37 Sub-Bandage Pressure Measurements Pressure Readout Electronic Sensor BandaPress R Pneumatic Sensor Tally R

38 Compression achieved at various static levels to compare dynamic sub-bandage pressures

39 Dynamic (Working) Pressures 150 mmhg 0 Static Static Pressures Set by Compression Short Stretch Dynamic Dynamic pressures via calf muscle contraction

40 Dynamic (Working) Pressures 150 mmhg 0 Static Static Pressures Set by Compression Dynamic Dynamic pressures via calf muscle contraction 150 mmhg Comparison of Different Bandage Types Efficient Dynamic Pressure Inefficient Low Dynamic Pressure 0 Cohesive Elastic Multilayer

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