The Hip book
Home » Orthopaedics » Fluid and Electrolytes

Fluid and Electrolytes


- See:
   - F & E in the Head Injured Pt
   - References
   - Hetastarch/Hespan

- Adult Trauma Patient:
    - initially the adult trauma pt should rapidly be given 2 liters of balanced salt solution w/ observation of response;
    - if there is no improvement in vital functions, than additional fluid load should be instituted with the addition of pRBC;
    - use of naloxonne, vasopressors, diuretics, and bicarbonate is rarely indicated in the initial resuscitation of the trauma patient;
    - metabolic acidosis seen in the early phase of the resusitation of trauma pt is due to poor tissue perfusion and will reverse w/ adequate volume has been restored;
    - as long as pt is in supine position, as much as 1000 ml of blood may be maintained w/o causing significant increase in peripheral pulse;
    - many trauma pts will have elevated levels of antidiuretic hormone from trauma, whether or not shock has occurred;
    - caution must be observed in allowing water intake, as dangerous water intoxication may occur with the intense thirst stimulus;
    - minimum requirements for fluid balance can be estimated from the sum of urine output necessary to excrete daily solute load (500 ml/ day) plus insensible (evaporative) water losses from the skin and resp tract (500-1000 ml/day) minus the amount of water produced from endogenous metabolism (300 ml/day);
    - kidney must excrete about 600 mOsm of solute/day (primarily Na, K, and urea) in the normal adult;
    - since maximum urinary concentrating ability is 1200 mOsm/kg, minimum urine output required to excrete the osmotic load is 500 ml/day;
         - it is customary to administer 2000-3000 ml of water daily to produce about 1000-1500 ml/day urine output, since there is no advantage gained by minimizing urine output;
- Maintenance Fluids:
    - 70 kg Male: D5 1/4 NS + 20 mEq KCl/lit at 125 ml/hr
    - will deliver about 3 liters of free water
    - Kg Method:
         - 1st 10 kg BW: 100 ml/kg/day (D10W 1/4 NS)
         - 2nd 10 kg BW:  50 ml/kg/day plus 1000 ml
         - > 20 kg - provide 20 ml/kg/day for ea kg over 20 kg;
         - < 10 kg: 4 ml/kg/hr of D10W 1/4 NS;
         - 10 - 20 kg   40 + (2 ml/kg/hr for kg > 10)
         - ...hence, for 15 kg = 40 + (2 x 5) = 50 ml/hr
         - > 20 kg: 40 ml/hr + 1 ml/kg/hr (for 30 kg = 40 + 30 = 70);
- Nutritional Requirements:
    - in children, kcal/kg/hr = ml/kg/hr
    - 50% calories, 35% fat, and 15% protein;
    - prolonged IV may result in Vit B1 (@THIAMINE[Thiamine) Defficiency;
- Resusitation for infants and children:
    - LR bolus 20 ml/kg x 2-3 as required
    - then pRBC 10 ml/kg x 1
    - continue fluid administration until CVP > 5 mm Hg;
- Crystalloid:
    - major disadvantage of isotonic crystalloids is their limited ability to remain within the intravascular space;
    - LR by end of 1 liter infusion expands the intravascular compartment by only 194 ml;
         - remaining 80% of fluid is lost to the intersitial space;
    - generally, two to four times as much crystalloid as 5% albumin or 6% hetastarch is required to achieve the same physiologic endpoints;
- Colloids:
    - greater ability to than crystalloids to remain w/in intravascular space and therefore more efficient volume expanders;
    - approximately 90% of exogenous albumin can be found in the IV space 2 hrs after administered;
    - serum half life of albumin is about 18 hrs;
    - synthetic colloids such as (hetastarch, hespan) have similar volume expanding abilities;
- Plasmanate (plasma protein fraction) is a 5% protein solution containing both albumin and alpha and beta globulins;
    - paradoxical hypotension has been noted during the infusion of plasma protein fraction and has been attributed to acetate, present as a
         buffer, or the presence of Hageman factor fragments;
    -                Na   Cl   K   Ca   Lactate              pH   Osmolarity
    - LR             130  109  4    3     28                 6.5     273
    - NaCl           154  154                                5.0     308
                                   Mg   Acetate   Gluconate
    - Plasmalyte A   140   98  5    3     27         23      7.4     294


Differential clearance of colloid and crystalloid solutions from the lung