Volume overload

At an optimum end-diastolic volume occurs at maximum stroke volume and cardiac output is achieved. 



Beyond this optimum volume, there volume overload, and stroke volume is diminished.



Refers to the state of one of the chambers of the heart in which too large a volume of blood exists within it for it to function efficiently. 



Ventricular volume overload is equivalent to an excessively high preload. 



Ventricular volume overload is a cause of cardiac failure.



The myocardium contracts more powerfully as the end-diastolic volume increases, as stretching of the myofibrils in cardiac muscle causes them to contract more powerfully due to a greater number of cross-bridges being formed between the myofibrils within cardiac myocytes.



Beyond this point the ability to contract diminishes due to loss of connection between myofibrils.



The common finding in volume overload  is high cardiac output with a low or normal afterload. 



The output may be high due to the inefficiency in valve disease, or it may be high due to shunting of blood in left-to-right shunts and arteriovenous malformations.



 Inverted u waves on the electrocardiogram, may be  seen in left ventricular volume overload.



Volume overload common among critically ill patients with kidney, heart, and liver disease is mainly as a result of aggressive fluid resuscitation.



Causes of left ventricular volume overload: 



Valvular heart disease



Aortic regurgitation



Mitral regurgitation, also causing left atrial volume overload



Congenital heart defects



Patent ductus arteriosus



Ventricular septal defect, also causing left atrial volume overload



Arteriovenous malformation and fistula



Giant hepatic haemangioma



High-output haemodialysis fistula



Right ventricular volume overload



Valvular heart disease



Tricuspid regurgitation



Pulmonary regurgitation



Congenital heart defects



Atrial septal defect, also causing right atrial volume overload



Removing fluid with diuresis or ultra filtration can i prove volume overload in critically  ill patients.



Removing fluid can lead to hypotension,renal insufficiency , neurologic events, and ototoxicity.



Hypertonic albumin solution or elastic bandages can mobilize extravascular volume during the active fluid removal phase of critical illness.



Administering albumin with furosemide in  patients with hypoalbuminemia is associated with increased urine volume and sodium excretion.



Patient with hypoalbuminemia have increased furosemide  volume distribution and decreased furosemide transportation efficiency at the proximal tubule.



Therefore intravenous albumin may improve the fluid removal rate with loop diuretics.



The exertion of external compression counteracts capillary fluid infiltration by increasing local tissue pressure and enhances reabsorption by squeezing fluid from the interstitial space into the veins and lymphatic system.



Compression reduces the diameter of major veins in the lower extremities, Which causes a reduction of local blood volume and redistribution of blood towards central circulation increasing preload and cardiac output.





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