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The physiology of edema.. Edema: The abnormal accumulation of fluid in a specific organ vs generalized. The abnormal accumulation of fluid in a specific.

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Presentation on theme: "The physiology of edema.. Edema: The abnormal accumulation of fluid in a specific organ vs generalized. The abnormal accumulation of fluid in a specific."— Presentation transcript:

1 The physiology of edema.

2 Edema: The abnormal accumulation of fluid in a specific organ vs generalized. The abnormal accumulation of fluid in a specific organ vs generalized. In capillary: Balance between hydrostatic pressure and oncotic (colloid osmotic) pressure. In capillary: Balance between hydrostatic pressure and oncotic (colloid osmotic) pressure.

3 Hydrostatic pressure: Intra-capillary vs interstitial Intra-capillary vs interstitial Capillary pressures vary: Capillary pressures vary: Nail bed capillaries: 32 mmHg at arteriolar end and 15 mmHg at venous end. Mean 25 mmHg. Nail bed capillaries: 32 mmHg at arteriolar end and 15 mmHg at venous end. Mean 25 mmHg. Hydrostatic pressure gradient: Hydrostatic pressure gradient: Intra-capillary hydrostatic pressure – interstitial fluid hydrostatic pressure Intra-capillary hydrostatic pressure – interstitial fluid hydrostatic pressure

4 Interstitial hydrostatic pressure: Varies from one organ to another: Varies from one organ to another: Subcutaneous tissue: Subatmospheric (-2 mmHg) Subcutaneous tissue: Subatmospheric (-2 mmHg) Liver, kidney: + Liver, kidney: + Brain: As high as 6 mmHg Brain: As high as 6 mmHg

5 Oncotic pressure: Capillary wall usually impermeable to plasma proteins and other colloids. Capillary wall usually impermeable to plasma proteins and other colloids. Only water and small solutes cross capillary wall. Only water and small solutes cross capillary wall. Crystalloids vs colloids Crystalloids vs colloids

6 These colloids exert an osmotic pressure of about 25 mmHg. These colloids exert an osmotic pressure of about 25 mmHg. The colloid osmotic pressure due to the plasma colloids=oncotic pressure. 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. Due to disturbance in hydrostatic and/or oncotic pressure between intra-capillary and interstitial component.

8 Organ specific: Brain: Cerebral edema Brain: Cerebral edema Lung: Intra-alveolar=pulmonary edema, intra-pleural=pleural effusion Lung: Intra-alveolar=pulmonary edema, intra-pleural=pleural effusion Peritoneum=ascites Peritoneum=ascites Severe generalized edema=anasarca Severe generalized edema=anasarca

9 Reduced oncotic pressure: Reduction in production of colloids--- plasma proteins. Reduction in production of colloids--- plasma proteins. Liver failure Liver failure Malnutrition Malnutrition

10 Increase in loss of colloids--- plasma proteins. Increase in loss of colloids--- plasma proteins. Nephrotic syndrome Nephrotic syndrome Catabolic states Catabolic states

11 Increase capillary hydrostatic pressure: Venous end: Heart failure, deep venous thrombosis, superior vena cava obstruction etc. Venous end: Heart failure, deep venous thrombosis, superior vena cava obstruction etc. Arterial end: Pre-capillary dilatation. Calcium channel blockers. Arterial end: Pre-capillary dilatation. Calcium channel blockers.

12 Increased interstitial oncotic pressure: Lymphatic obstruction: Lymphatic obstruction: Primary vs secondary group. Primary vs secondary group.

13 Capillary leaks: Result of capillary damage: Result of capillary damage: Pleura: Infections, tumors Pleura: Infections, tumors Alveoli: Inhalation of noxious substance, eg chlorine gas etc Alveoli: Inhalation of noxious substance, eg chlorine gas etc

14 Diverse causes of edema: Anaemia Anaemia Hypothyroidism Hypothyroidism

15 Hormones involved in edema: Renin angiotensin aldosterone system: secondary hyperaldosteronism Renin angiotensin aldosterone system: secondary hyperaldosteronism ADH (Vasopressin) ADH (Vasopressin) ANP ANP

16 Clinical physiological approach to edema: Hypervolemia: Hypervolemia: Vs Vs Normovolemia: Normovolemia:

17 Jugular venous pressure: Elevated and pulsating: Elevated and pulsating: =hypervolemia =hypervolemia Then edema: Then edema: Due to increased capillary hydrostatic pressure: Due to increased capillary hydrostatic pressure: Cardiac failure, or isolated RV (pulm HT) Cardiac failure, or isolated RV (pulm HT) Hypervolemia caused by transfusion Hypervolemia caused by transfusion

18 Normal JVP: Unilateral Unilateral Unilateral increase in capillary pressure Unilateral increase in capillary pressure Deep venous thrombosis Deep venous thrombosis OR: OR: Unilateral increase in interstitial colloid osmotic pressure Unilateral increase in interstitial colloid osmotic pressure Lymphatic obstruction (radiation, filariasis, congenital) Lymphatic obstruction (radiation, filariasis, congenital)

19 Edema due to capillary hypertension with normal venous pressure: Edema due to capillary hypertension with normal venous pressure: Pre-capillary dilatation: Pre-capillary dilatation: Calcium channel blockers Calcium channel blockers

20 Generalized edema without hypervolemia: Decreased capillary colloid oncotic pressure: liver, kidney, catabolic states, malnutrition. Decreased capillary colloid oncotic pressure: liver, kidney, catabolic states, malnutrition. Increased interstitial colloid oncotic pressure: lymphatic. Increased interstitial colloid oncotic pressure: lymphatic. Increase in capillary permeability: Inflammation, toxins, severe anaemia 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. 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: 3 waves in the curve:

22 a-wave: atrial systole a-wave: atrial systole c-wave: bulging of tricuspid valve into R atrium c-wave: bulging of tricuspid valve into R atrium v-wave: rise in atrial pressure, just before tricuspid valve opens during diastole. v-wave: rise in atrial pressure, just before tricuspid valve opens during diastole. Clinical application of these 3 waves: Clinical application of these 3 waves:

23 Sinus rhythm or not. Sinus rhythm or not. Pulmonary hypertension Pulmonary hypertension 3`rd degree heart block 3`rd degree heart block Patency between SVC and RA Patency between SVC and RA Tricuspid regurgitation and stenosis Tricuspid regurgitation and stenosis


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