What determines intracellular/extracellular osmotic pressure?
Na determines intracellular/extracellular osmotic pressure
1) most comon cause is iatrogenic
2) first sign is weight gain
What cellular process can release a significant amount of H20
0.9% normal saline:
Na 154 and Cl 154
Lactate Ringer's solution:
1) LR; ionic composition of plasma:
Formula for plasma osmolarity:
(2 x Na)+(glucose/18)+(BUN/2.8)
Estimates of volume replacement:
1) 4cc/kg/h for 1st 10kg
2) 2cc/kg/h for 2nd 10kg
3) 1cc/kg/hr for each kg after that
4) best indicator of adequate volume replacement is urine output
What is the fluid loss in open abdominal operations:
During open abdominal operations, fluid loss is 0.5-1.0L/h unless there are measurable blood losses
At what point do you need to replace blood loss?
usually do not have to replace blood loss unless it is >500cc
Insensible fluid losses:
1- 75% skin
2- 25% respiratory
3- pure water
IV replacement after major adult gastrointestinal surgery:
1) during operation and 1st 24 hours, use LR2) After 24 hours, switch to D5 1/2 NS with 20mEq K1- 5% dextrose will stimulate insulin release, resulting in amino acid uptake and protein synthesis (also prevents protein catabolism)
2- D5 1/2NS @ 125/h provides 150g glucose per day (525kcal/day)
GI fluid secretion:
Biliary System: 500-1,000 ml/day
Pancreas: 500-1,000 ml/day
Duodenum: 500-1,000 ml/day
Normal K+ requirement:
Normal Na+ requirement:
Normal K+ requirement: 0.5-1 mEq/kg/day
Normal Na+ requirement: 1-2 mEq/kg/day
Saliva- K+ (highest concentration of K+ in the body)
Stomach- H+ and Cl-
Small Intestine- HCO3-, K+
Large Intestine- K+
What do you replace gastric losses with?
Gastric losses- replacement is D5 1/2NS with 20mg K+
What do you replace pancreatic/biliary/small intestine losses with?
replacement is LR with HCO3-
What do you replace Large intestine (diarrhea) losses with?
replacement is LR with K+
How is volume of GI losses replaced?
GI losses- should generally be replaced cc/cc
What should urine output be kept at?
Urine output- should be kept at least 0.5cc/kg/h; should not be replaced, usually a sign of normal postoperative diuresis
1) Normal: 3.5-5
2) Hyperkalemia- peaked T waves initial finding on EKG
1- calcium gluconate (membrane stabilizer for the heart)
2- sodium bicarbonate (causes alkalosis, K enters cell in exchange for H)
3- 10U insulin and 1 ampule of 50% dextrose (K driven into cells along with glucose)
5- dialysis if refractory
3) Hypokalemia- T waves disappear
1- may need to replace Mg+ before you can correct K+