Hemodynamic Disorders, Thrombosis and Shock

Dr. Eric P. Lasala, DPSP

n Approximately 60% of body weight is water

u 2/3 intracellular

u 1/3 extracellular

« Mostly instertitial fluid

« 5% is found in the plasma

n Edema

u Signifies an increase in the fluid in instertitial tissue space

u Depending on the location of this abnormal fluid accumulation they maybe called in different names

n Forms of edema

u Hydrothorax

u Hydropericardium

u Hydroperitoneum (ascites)

u Anasarca (generalized body edema, with profound subcutaneous tissue swelling)

n Causes of Edema

u Increased capillary pressure

u Increased plasma colloid oncotic pressure

u Primary retention of sodium

Factors involved in Fluid Movement

n Vascular Hydrostatic Pressure

u The pressure exerted by a volume of fluid on the walls of its container

n Plasma Colloid Oncotic Pressure

u The force exerted by protein to attract fluid to itself by means of osmosis

Increased Hydrostatic Pressure

n Causes

u Impaired venous outflow

« Causes an increase in the local hydrostatic pressure

« Example: deep venous thrombosis in the lower extremities

n Causes

u Congestive Heart Failure

« Results from a generalized increase in venous pressure

« Associated with a reduced cardiac output and reduced renal perfusion triggering RAS with a resulting sodium and water retention

« Failure to increase cardiac output with extra fluid load results in increase venous pressure and eventually edema

Reduced Plasma Osmotic Pressure

n Causes

u Excessive loss of albumin

u Reduced synthesis of albumin

u Examples:

« Nephrotic Syndrome

« Liver pathology

« Protein malnutrition

n Reduction of plasma oncotic pressure results to a net movement of fluid into the instertitial tissues and a resultant plasma volume contraction that leads to reduced renal perfusion which triggers secondary aldosteronism which causes sodium and water retention

Lymphatic Obstruction

n The lymphatic system is responsible for absorbing back the net flow of fluid outside the vascular channels back to the circulatory system

n When obstructed, the resulting edema is usually localized

n Examples:

u Filariasis ( elephantiasis)

u Surgery (MRM)

u Neoplastic Obstruction

u Radiation Fibrosis

Sodium and Water Retention

n Salt retention with obligate accompanying water causes an increased hydrostatic pressure because of the expansion of intravascular fluid volume and diminished vascular colloid osmotic pressure

Clinical Significance of Edema

n Subcutaneous tissue edema

u Seen in cardiac or renal failure

u Signals underlying disease

u Impairs wound healing

u Decreased clearance of infection

n Pulmonary edema

u May cause death by interfering with normal ventilatory function

u Characteristic “frothy” sputum

u Creates a favorable condition for bacterial infection

n Brain edema

u The fluid that accumulates within the cranial cavity may increase considerably to push the brain tissue out of a hard fixed bony structure into its only possible exit point which is the foramen magnum (herniation)

n The overall effect of edema to the patient may vary considerably from merely annoying to fatal

n The location, the organs involved and the underlying causes of the different types of edema are the factors to be considered