Fluids, volume regulation and volume disturbance Flashcards
Extracellular fluid component (2)
1) Interstitial
2) Intravascular
90% of fluid returns via?
Venules
The rest through the lymphatic system
How are body water and tonicity regulated?
ADH
Hypothalamic osmoreceptors have an osmotic threshold of about ___ mOsm/kg. Above this level ADH release is stimulated.
289
Hypothalamic thirst center neurons is activated when (3)
1) Increase in plasma sodium of 2 mEq/L
2) increase in plasma osmolality of 4 mOsm/L
3) loss of potassium from thirst center neurons and
angiotensin II
3 criteria of SIADH
1) The patient must be euvolemic or hypervolemic
2) The urine must be inappropriately concentrated (plasma osmolality <280 mOsm/kg, urine osmolality >100 mOsm/kg)
3) Renal, cardiac, hepatic, adrenal, and thyroid function must be normal
The primary therapy for SIADH is?
Water restriction
Demelocycline
Where is angiotensinogen produced?
Liver
Intravascular space half-life of colloids?
3-6 hours
There are two albumin preparations?
5%
25%
Colloid osmostic pressure under normal circumstances?
20 mmHg
The heterogeneous preparation contains polymerized
molecules with molecular weights of between 20,000 and 100,000 daltons.
HES 6%
HES is metabolized by?
HES accumulates where?
HES is excreted where?
Amylase
Reticuloendothelial cells
Kidneys
What clotting factor is prolonged when HES is aministered?
Partial thromboplastin time
It has dilutional effects on clotting factors, and the hetastarch molecules can move into organizing fibrin clot.
Recommended dose of HES?
not more than 20 mL/kg
A fluid preparation with water-soluble, polymerized glucose molecules. It has 2 preparations namely?
Dextran
Dextran 40 and 70 (molecular weights of the respective solutions are 40 and 70 kilodaltons)
Nice to know
What situations might be appropriate for the use of hypertonic saline?
Hypertonic saline (usually 3%) has been used extensive cancer resections; for hypovolemic shock, slow correction of symptomatic chronic hyponatremia, transurethral resection of the prostate syndrome, and increased intracranial pressure; and to reduce peripheral edema after major fluid resuscitations. It has been used in far forward combat situations and in trauma patients with prolonged transportation times (rural areas), but its use is still not extremely common.
A large laparotomy sponge is equivalent to know much blood?
100 mL
How much fluid is:
1) Liber fluid administration
2) Restrictive fluid administration
1) 12 to 15 ml/kg/hr
2) 4 to 8 ml/kg/hr
Blood pressure is not significantly affected until approximately ___ of blood volume is lost.
30%
