PT-PAP 101 Hydrodynamic Principles

PT-PAP 101 Hydrodynamic Principles

• Hydrodynamic principles are used in hydrotherapy, a therapeutic treatment performed in underwater.
• Hydrotherapy is suitable for conditions where land-based exercise is not.
• Hydrotherapy uses warm water (90-95°F).
• It's a popular treatment for patients with neurological and musculoskeletal conditions.

Objectives

• Students should be able to explain hydrodynamic principles.
• Students should be able to correlate hydrotherapy principles to rehabilitation aspects.

Uses in Physiotherapy

• Hydrotherapy, also known as aquatherapy, assists in rehabilitation and recovery from clinical conditions unsuitable for land-based exercises.

Hydrodynamic Principles

• Buoyancy
• Turbulence
• Friction
• Hydrostatic pressure
• Relative density

Buoyancy

• Archimedes' Principle: A fully or partially submerged body experiences an upward thrust equal to the weight of the fluid it displaces..
• 90% body weight reduction occurs when fully immersed.
• Percentage off-loaded increases with immersion depth.

Clinical Significance of Buoyancy

• Provides relative weightlessness and joint unloading in water. This makes exercises easier on joints.
• Allows three-dimensional access to the patient, enabling easier assessment and treatment of specific areas.

Center of Buoyancy

• The reference point of an immersed object where buoyant forces act vertically.
• Vertical forces that don't intersect the center of buoyancy create rotational motion.
• A vertical position of the body will have the center of buoyancy at the sternum.
• A posteriorly placed center of buoyancy causes the patient to lean forward.
• An anterior placed center of buoyancy will cause the patient to lean back.

Clinical Application of Buoyancy

• Immersion to the symphysis pubis offloads approximately 40% of body weight.
• Immersion to the umbilicus offloads around 50% of body weight.
• Immersion to the xiphoid offloads 60% or more of body weight.
• Immersion to the shoulders offloads around 85% of body weight, depending on arm position.

Viscosity

• Friction between liquid molecules creates resistance to flow.
• Viscosity creates resistance to all active movement.

Clinical Significance of Viscosity

• Increasing surface area moving through water will increase resistance to movement.
• Stabilizing an extremity proximally requires more work from the patient.
• Stabilizing an extremity distally requires less work from the patient.

Surface Tension

• Surface of a fluid acts as a membrane under tension.
• Measured as force per unit length.
• Extremity moving through the surface of the water requires more work as resistance is increased.
• Equipment at or near the surface of the water increases resistance to movement.

Relative Density

• Relative density compares the density of an object to the density of water at 4°C.
• Objects denser than the water sink.
• Objects less dense than the water float.
• Water (1 cm²) has a mass of 1 gram.

Hydromechanics

• Physical properties and characteristics of fluid in motion.
• Components of flow motion (Laminar flow, Turbulence flow,and drag).

Laminar Flow

• Movement where all molecules move parallel to each other.

Turbulence Flow

• Movement where molecules do not move parallel—typically faster movement

Drag Force

• Most important concept in aquatic therapy.
• Frictional resistance of an object.
• Greater surface area or unstreamlined body position increase resistance.
• Position or shape changes can influence drag.
• Increased speed of motion increases drag (streamlining).

Clinical Significance of Drag Force

• Increased speed increases resistance to movement—patients need to work harder.
• Equipment like gloves, paddles or boots used in therapy increase resistance as the patient moves the limb through the water.

Turbulence

• The eddies in the wake of objects moving through fluids.
• Degree varies with speed of movement and body shape.
• Used in hydrotherapy to assist or resist movement, and to improve balance, coordination.

Hydrostatic Pressure

• Molecules in a fluid exert thrust on every part of an immersed body.
• Pascal's law states forces are equally distributed on all surface areas at a given depth.

Clinical Significance of Hydrostatic Pressure

• Increased pressure reduces or limits fluid accumulation.
• Aids venous return, inducing bradycardia.
• Can decrease peripheral blood pressure while increasing BP around the heart.
• Important consideration for patients with chronic heart failure (CHF) or Coronary Artery Disease (CAD).

This quiz focuses on the hydrodynamic principles applied in hydrotherapy, a crucial treatment method for patients with various conditions. Students will explore concepts such as buoyancy, turbulence, and hydrostatic pressure, correlating these principles to rehabilitation practices. Test your understanding of how water dynamics facilitate therapeutic exercises and recovery.