NURS 2090 Lecture Notes - Hemoglobin, Arthralgia, Asystole
29 views17 pages
Altered Fluid, Electrolyte and Acid-Base Balance
Fluid, Electrolytes and Acid-Base Balance
Water and electrolyte intake and output are regulated through hormonal and neural interactions
Most metabolic processes in the body result in the production of acid
Acid is removed through the lungs (CO2) and kidney (acid/base balance)***EXAM QUESTION!!!
Distribution of Ions
Chlorine usually follows Na+
Interstitial fluid (ISF) (OUTSIDE CELL)
- high Na, Cl, Ca
- low K, Mg, P
- med HCO3
Intracellular Fluid (ICF) (INSIDE CELL)
- high K
- low Ca, Na, HCO3, Cl
- mod P, Mg
3 Na out to ECF/ 2 K in, which goes against the concentration gradient (since Na+/K ATPase requires
energy) makes sense why the fluid INSIDE the cell has higher K.
(Potassium is pumped inside AGAINST the concentration gradient. 2 inside-- when if there was no
energy it would want to leak out due to the concentration gradient).
Think of electrolyte imbalance if you see:
- cognition changes
- breathing problems
-massive burns/ blood loss
Caution: Diuretics and BP meds can create
an electrolyte imbalance
Altered Sodium Balance
- Aldosterone is used for sodium balance. It helps reabsorb Na + water (while excreting K+).
Hyponatremia - Decreased levels of sodium in the blood (less than 135mEq/L)
- Can be caused by excessive Sweating, Vomiting/Diarrhea, cirrhosis
(i.e. a long distance runner). Need to intake electrolytes/sodium because if you just drink water, you will
only dilute the salt even more. ** limit intake of water
Muscle effects: (↑depolarization)
Muscle twitching & weakness
Reduced extracellular circulating volume leads to:
Tachycardia (↑ HR reflex tachycardia)
Oliguria: Reduced urine output – body tries to retain Na+
Anuria: absent urine output – body tries to retain Na+
Altered Neuronal FX leads to (this is due to the fact that there can be cerebral edema,
increasing intercranial pressure) brain swelling causes most of the symptoms!
Nausea + vomiting
* means one of the first signs
Hypovolemic hyponatremia- Total body water (TBW) decreases; total body sodium (Na+)
decreases to a greater extent. The extracellular fluid (ECF) volume is decreased.
Hypervolemic hyponatremia-Total body sodium increases, and TBW increases to a greater
extent. The ECF is increased markedly, with the presence of edema.
Hypernatremia-Increased levels of sodium in the blood (over 145mEq/L)
- Caused by excess sodium intake or loss of body water.
- Think about DEHYDRATION SYMPTOMS
Altered cell metabolism causes:
Fluid shifts cause:
Thirst- need water to dilute (↓ concentration)
Hypertension (↑ Na linked to HTN)
Altered Potassium Balance
- cannot wait on this test- CRITICAL VALUES!
-has an 80% filtration rate through the kidney (aldosterone= hormone regulator)
-Any time there is sodium- potassium membrane disturbance, it will lead to muscle cramps +
- Potassium is needed for cardiac function and skeletal/smooth muscle contraction
Hypokalemia- Potassium levels of less than 3.5mEq/L in the blood
- Caused by diuretics, severe vomiting and diarrhea
Lower potassium levels in the extracellular space will cause hyperpolarization of the resting membrane potential.
This hyperpolarization is caused by the effect of the altered potassium gradient on resting membrane potential. As a
result, a greater than normal stimulus is required for depolarization of the membrane in order to initiate an action
- In the heart, hypokalemia causes hyperpolarization in the myocytes' resting membrane potential. The more
negative membrane potentials in the atrium may cause arrhythmias because of more complete recovery from
sodium-channel inactivation, making the triggering of an action potential more likely. In addition, the reduced
extracellular potassium (paradoxically) inhibits the activity of the IKr potassium current and delays ventricular
repolarization. This delayed repolarization may promote reentrant arrhythmias.
Dizziness (↓BP causes this)
Cardiac Arrhythmias- life threatening
Muscle Weakness +Leg Cramps, which cause:
Anorexia (loss of appetite)
Polyuria + poorly concentrated urine
Hyperkalemia- Potassium levels of more than 5.0mEq/L in the blood
- Is Iatogenic, due to drugs or renal failure (not excreting enough), trauma
- is a precursor to MI
- Increased extracellular potassium levels result in depolarization of the membrane potentials of cells. This
depolarization opens some voltage-gated sodium channels, but not enough to generate an action potential. After a
short while, the open sodium channels inactivate and become refractory, increasing the threshold needed to generate
an action potential. This leads to the impairment of neuromuscular, cardiac, and gastrointestinal organ systems. Of
most concern is the impairment of cardiac conduction which can result in ventricular fibrillation or asystole.
Altered membrane potential causes:
flaccid paralysis – loss of muscle tone (because of effect on Na channels)
Water and electrolyte intake and output are regulated through hormonal and neural interactions. Most metabolic processes in the body result in the production of acid. Acid is removed through the lungs (co2) and kidney (acid/base balance)***exam question!! 3 na out to ecf/ 2 k in, which goes against the concentration gradient (since na+/k atpase requires energy) makes sense why the fluid inside the cell has higher k. (potassium is pumped inside against the concentration gradient. 2 inside-- when if there was no energy it would want to leak out due to the concentration gradient). Caution: diuretics and bp meds can create an electrolyte imbalance. It helps reabsorb na + water (while excreting k+). Hyponatremia - decreased levels of sodium in the blood (less than 135meq/l) Can be caused by excessive sweating, vomiting/diarrhea, cirrhosis (i. e. a long distance runner). Need to intake electrolytes/sodium because if you just drink water, you will only dilute the salt even more.