Med Surg: 1

Med Surg 1


Class one


Fluid, Electrolytes, and pH balance


hypotonic solution – fewer solutes than isotonic. (½ NS)

Isotonic solution – equal amount to the average bod fluids (NS)

hypertonic solution – more solutes than isotonic. (3%NS)


Fluid balance:

  • HypOvolemia – Volume deficit
    • causes: V/D, insensible, burns, 3rd spacing.
    • s/s:
      • increase: HR, RR. (compensating for the decrease in intravascular volume volume)
      • Decrease: BP, UO, turgor of skin, and weight.
      • restless, and lethargic
  • HypERvolemia – Volume excess
    • causes: HF, SIADH (too much ADH hormone), too much IV fluids
    • s/s:
      • Increase: HR, BP, Edema, weight, JVD
      • crackles, confusion, HA (neuro s/s from the increased intracranial pressure)
    • we are mostly concerned


osmolality of a “normal” person’s serum is 280-300 mOsm (NS is about 300)

  • The higher the osmolality the more hypertonic the fluid is.


Factors affecting the fluid volume, and electrolytes:

  • HF, N/V/D, fluid and food intake and output, chronic illness (renal, liver, Adrenal)
  • Measure I/O’s!! avoid trying to catch up with fluid balance, stay on top of it before it gets out of control.
  • recording I/O’s, and daily weights will allow us as nurses to manage the volume of fluid and correct issues. Avoid trying to catch up with IV fluid replacements
  • 1 liter weighs 1 kilogram
  • Confusion is an important sign when a person is out of homeostasis.
  • OLD people are at high risk! especially if they are getting
  • a person’s I is 1200ml and O is 3600 ml. The person is in a fluid volume deficit.


Trends are VERY important when looking at labs and s/s!! Also look at the patient and look for errors in the sampling when there is a result that does not make sense.



  • Cations (+): K+(3.5-5), Na+(135-145), Ca+(8.6-10.2) Mg+  (1.5-2.5)
  • Anions (-): Cl, HCO3, PO4⁻  (2.4-4.5)
  • Extracellular Fluid: Na, Cl, and HCO3
  • Intracellular fluid: K, Mg, and PO4

other normal lab levels

  • WBC 5-10
  • Hgb 15
  • Hct 40% (about 3x the Hgb)



  • Hyper – >145 (135-145)
    • High concentration of the Na in the ECF pulls the fluid out of the cells causing cells to shrink
    • Usually caused by dehydration
    • can be caused by: diarrhea, hyperaldosteronism, DI, fluid restriction. (loss of fluid, or gain of Na)
    • s/s: orthostatic hypotension, thirst, restlessness, agitated and disorientated, increase in tone of MM or fatigue.  (FALL RISK)
    • REhydrate the person with ½ NS slowly if dehydration is the problem. do this slowly so that the cells do not swell too much (brain cells swelling will cause change in LOC)
  • HypO – <135 mEq
    • Low concentration of Na outside the cells cause fluid to move into the cells where there is a higher concentration of Na causing the cells to swell.
    • MOST common electrolyte balance issue seen in the hospital.
    • caused by: N/V, suctioning, diarrhea, water enama, SIADH.
    • s/s: Confusion, change in LOC, seizures, HA, decrease in tone or fatigue, cramping, Orthostatic hypotension, tachycardia.
    • restrict water, replace Na, ADH antagonist,  

Both low and high levels of Na will throw off a person’s LOC

The increased rate of change will increase the s/s


K +  (3.5-5) low causes PVC (early beats), premature arrhythmias. high levels causes, bradycardia, asystole.

  • HyperK > 5.0
    • caused by: an infusion that was too quick, burns, tumor lysis, crushing injuries, renal injuries, adrenal insufficiency, DM that is poorly controlled.
    • acidosis can increase K in the ECF, insulin will carry the K back into the cell.
    • fix this with: stop K intake, Kayexalate, IV insulin with glucose. (sometimes albuterol will be ordered to decrease K as well, the albuterol will stimulate the release of insulin then the insulin will move the K into the cell)


  • HypoK <3.5
    • causes: suction, N/V/D, alkalosis, increased insulin
    • s/s: irregular HR, fatigue, cramps, slow shallow respirations (to compensate if they are alkalotic)


  • Give magnesium before potassium if IV
  • monitor closely if the K dose is given then their output stops.


  • Hypercalcemia (8.5-10.2)
    • administer diuretics that excrete Ca
    • causes: immobility, increased parathyroid hormone, increase calcium containing antacids
    • decreased neuromuscular excitability, mm weakness, decreased clotting time


  • HypoCa:
    • causes: alkalosis, bone issues, decrease parathyroid hormone, malnutrition, blood transfusion
    • s/s:
    • chvostek’s sign(cheek twitch), trousseau’s (decorticate posture in hand and arm when a bp cuff is put on)


  • hyperMagnesemia (>2.5 mEq/L)
    • causes: increased intake,
    • s/s: flaccid muscles, slow resp rate, weak muscles.
  • HypoMag <1.5 mEq
    • causes: D/V, ETOH abuse, nutritional issues, and suctioning.
    • s/s: tetany, seizures, lethal dysrhythmias.
    • replace the mag,
  • phosphate (2.5-4.5)
    • not as essential
    • part of ATP
    • hypophosphatemia
      • causes: ETOH withdrawal, refeeding syndrome, DKA recovery
      • s/s: weakness, rhabdomyolysis, confusion,
    • hyperphosphatemia
      • causes: renal failure, chemo,
      • s/s: lethargy, tetany, drowsiness,