2 Edema:The abnormal accumulation of fluid in a specific organ vs generalized.In capillary: Balance between hydrostatic pressure and oncotic (colloid osmotic) pressure.
3 Hydrostatic pressure: Intra-capillary vs interstitialCapillary pressures vary:Nail bed capillaries: 32 mmHg at arteriolar end and 15 mmHg at venous end. Mean 25 mmHg.Hydrostatic pressure gradient:Intra-capillary hydrostatic pressure – interstitial fluid hydrostatic pressure
4 Interstitial hydrostatic pressure: Varies from one organ to another:Subcutaneous tissue: Subatmospheric (-2 mmHg)Liver, kidney: +Brain: As high as 6 mmHg
5 Oncotic pressure:Capillary wall usually impermeable to plasma proteins and other colloids.Only water and small solutes cross capillary wall.Crystalloids vs colloids
6 These colloids exert an osmotic pressure of about 25 mmHg. The colloid osmotic pressure due to the plasma colloids=oncotic pressure.
7 Edema:Due to disturbance in hydrostatic and/or oncotic pressure between intra-capillary and interstitial component.
16 Clinical physiological approach to edema: Hypervolemia:VsNormovolemia:
17 Jugular venous pressure: Elevated and pulsating:=hypervolemiaThen edema:Due to increased capillary hydrostatic pressure:Cardiac failure, or isolated RV (pulm HT)Hypervolemia caused by transfusion
18 Normal JVP: Unilateral Unilateral increase in capillary pressure Deep venous thrombosisOR:Unilateral increase in interstitial colloid osmotic pressureLymphatic obstruction (radiation, filariasis, congenital)
19 Edema due to capillary hypertension with normal venous pressure: Pre-capillary dilatation:Calcium channel blockers
20 Generalized edema without hypervolemia: Decreased capillary colloid oncotic pressure: liver, kidney, catabolic states, malnutrition.Increased interstitial colloid oncotic pressure: lymphatic.Increase in capillary permeability: Inflammation, toxins, severe anaemia
21 Pressure changes in the heart: Atria: Study curve in Ganong: jugular venous pressure curve, also known as flobogram, indicative of pressure changes in superior vena cava/ right atrium.3 waves in the curve:
22 a-wave: atrial systole c-wave: bulging of tricuspid valve into R atriumv-wave: rise in atrial pressure, just before tricuspid valve opens during diastole.Clinical application of these 3 waves:
23 Sinus rhythm or not.Pulmonary hypertension3`rd degree heart blockPatency between SVC and RATricuspid regurgitation and stenosis