MEDSURG Final Exam Study
Guide
1. Understand the ABG’s and how to decide if a patient is in resp acidosis or
resp alkalosis, metabolic acidosis, or metabolic alkalosis.
2. Understand the function of potassium, sodium, and calcium in the body-
especially the heart and how to administer these electrolytes. Be able to
correct the calcium using the calculation.
- Sodium: Na
- Normal value: 135-145
- Hyponatremia <135
- Common imbalance in the elderly caused by Na loss or water
gain
- Symptoms: decrease BP, poor skin turgor, headache,
nausea, cramps
- If seizure occurs: small infusion of 3%-5% NaCl SLOWLY
- Hypernatremia >145
- Sodium gain or water loss
- Problem with elderly/pts who can’t sense thirst or don’t
meet fluid needs
- Symptoms: increase in temp, dry swollen
tongue, neuro symptoms/changes=FIRST sign
usually
- Potassium: K
- Normal value: 3.5-5.0
- K+ necessary for normal cardiac rhythms, necessary for
skeletal and smooth muscle contraction, K+ helps make
glycogen deposit in the liver
- K imbalances can be life threatening
- Hyperkalemia >5.0
- Manifestations: cardiac changes & dysrhythmias, ECG
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weakness, GI cramps
- Management: Give diuretics to excrete K+, 10 units
regular insulin IV push with glucose (1 amp D50), Beta-2
agonist (albuterol MDI), Kayexalate (ion-exchange resin)
- Hypokalemia <3.5
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- Manifestations: fatigue, dysrhythmias, DTRs,
constipations, muscle weakness, anorexia, ECG changes:
flat T waves or inverted T waves or both, suggesting
ischemia, and depressed ST segments
- Med Management: increase PO of K+, give KCL
supplements when patient is on loop or thiazide
diuretics to prevent hypokalemia
- KCl should be administered IV at rate of 10-20
mEq/L per hour → rapid infusion can cause
CARDIAC ARREST
- Hold KCl unless urine output is at least 0.5 ml/kg
of body weight per hour
- Calcium: Ca
- Normal Value: 9-11
- Ca++ works as an enzyme co-factor for clotting and hormone secretion.
Stored in parathyroid glands, maintains plasma membrane
stability- particularly in the cardiac cell nerve receptors, aids in
the transmission of nerve impulses and contraction of muscles
- Corrected Calcium:
- Measured total serum Ca++ level (mg/dl) = 0.8 x (4.0 –
measured albumin level [g/dL]) = corrected total
calcium concentration (mg/dL)
- Pt’s serum calcium level is reported as 7.5 mg/dL
and serum albumin is 2.5 g/dL.
- 4.0 – 2.5 = 1.5 g/dL (albumin difference)
- 1.5 x 0.8 = 1.2
- 1.2 + 7.5 = 8.7 mg/dL (corrected calcium)
- Hypocalcemia: <9
- Manifestations:
- Tetany- paresthesias of nose, ears, fingertips that
progresses to painful muscle spasms and
convulsions; Positive Chvostek’s sign- cheek
twitch; Positive Trousseau’s sign- carpal spasm of
hand- with BP cuff inflation; Hyperreflexia;
Laryngospasm; Arrhythmias- VF, torsades de
pointes, Long QT, ↓ Cardiac contractility and ↓
blood pressure, Hypomagnesemia
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- trousseau’s chvostek’s
- Meds: Emergency Management:
- Administer Calcium Gluconate or Calcium Chloride
by slow IV push (0.5-1.0 ml/min)
- Maximum rate for intermittent infusion is 200 mg/min.
- For Non-Acute Hypocalcemia:
- Give Calcium Carbonate PO with Vitamin D to
help with absorption of Ca++ in the GI tract
- May need to give Magnesium if serum levels are low
- Hypercalcemia: >11
- Levels >12= coma ; <14=death
- Causes: increase Vitamin D and A,
hyperparathyroidism, metastatic cancer to bone
- Manifestations: fatigue/weakness, constipation,
dehydration, ECG changes= decreased heart
rate, heart blocks, shortened QT interval and
depressed T Wave; kidney stones
- Med Management: IV fluids followed with loop
diuretics (lasix) → increase hydration (IV fluids)
to 3000-4000 ml/day to flush Ca++ and to ↓
calculi formation, synthetic Calcitonin can be
given to lower Ca++ levels, IV calcitonin-promotes
renal excretion of Ca, antiemetics for nausea, IV
biphosphates to reduce bone resorption
- Magnesium:
- Hypomagnesium Mg+ < 1.5 mEq/L
- Causes:
- Alcoholism
- Hemodialysis
- Poor dietary intake
- Poor absorption of by GI tract
- Excessive Mg+ loss from GI tract (diarrhea)
- Kidney disease(primary aldosteronism,
DKA, hyperparathyroidism)
- Sepsis, burns, some wounds
- S/Sx:
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