Discuss the physiology of "third-spacing" & who are more @ risk for developing this? Fundamentals 1363 and ATI 408
Fluid shifts from vascular space into an area where it is not readily accessible as extracelluar fluid. This fluid remains in the body but is essentially unavailable for use, causing an isotonic fluid volume deficit.
@ Risk patients: those with edema,(I thought Mrs. Semillo said this affected Alcoholics can anyone confirm that and add to whom else this would affect)
Body cavities affected are the peritoneal space and pleural cavity
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Brain edema
(aka wet brain - alcoholics): increased intracellular or extracellular fluid in brain tissue; cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries; an increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of cerebrospinal fluid flow.
Ø Third spacing - most common extra loss in a trauma or surgical patient (basically edema).
· Third spacing results from burn wounds, pleural effusions, etc. Edema is the body’s response to injury.
· Third spacing means there is an increase in the patient’s weight as well as total body water and salt, but the fluid in the 3rd space is not supporting perfusion. You still have partially empty blood vessels.
· In the abdomen, fluid goes to 1) peritoneal cavity (ascites), 2) bowel lumen, 3) bowel wall “boggy”
· Other losses: chest tubes, NG tubes/gastrostomy, drains, diarrhea, vomiting
· Chest tubes – fluid has composition of blood/serum; replace with LR
· NG tube/gastrostomy – drainage color is important to determine tonicity
· Clear drainage (only contains spit and gastric acid) is replaced with 1/2NS + 10-20 cc KCl/L
· Green/yellow drainage (biliary secretions, pancreatic bicarb.) Any secretions past the pylorus are isotonic and replaced by LR.
· Third space losses are isotonic (so if you try to replace the fluid with 1/4 NS, your serum Na+ will decrease). The replacement must also be isotonic. [Na+] = 140, Osmo = 280
· After surgery, you must give extra fluid to replace what is being third spaced. Fluid loss depends on length of surgery.
· First 2 -3 days post-op - give a lot more fluid to maintain urine output.
· At about 36-48 hrs, the patient starts to mobilize the third space fluid, and suddenly the patient is urinating much more fluid than what’s put in. If third space losses aren’t replaced, urine output will be compromised.
· So in non-surgical patients, weight gain is seen as a bad thing, but in surgical patients, it’s expected and if not seen, probably means they’re not getting enough fluid.
http://www.muhealth.org/~md2003/draft7/2-12pediactric.doc
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