how does potassium affect blood pressure and heart rate?

[bailyoneohnine]

I'm having trouble with this because I've heard hypokalemia can both raise and lower your blood pressure and both explanations seem to make sense:

a) low potassium = muscle weakness = vessels can't constrict = low blood pressure

or

b) low potassium = high sodium = fluid fallows sodium = high blood pressure

which one is it!?!

[PrereqTaker89]

Bump. I'm interested to hear responses.

[ItsThatJenGirl, CNA]

I think it really depends on the underlying cause of the low or high potassium. Neither high nor low blood pressure is listed as a s/s for either hypo or hyperkalemia though (at least in my book/notes) - I don't think it's as good an indicator as something like a serum level, or even peaked or flattened T waves.

[Triddin]

I've never heard of hypokalemia directly affecting blood pressure. Potassium levels can affect your action potentials and therefore causing an arrythmia, which in turn could affect your cardiac output which could result in hypotension if the patient can't compensate for the loss of cardiac output.

[OcMurse93]

First of all, im not sure that hypokalemia will lead to hypernatremia.

Secondly, both are more or less correct. One is a constriction issue, and the other is a fluid issue. Both cause the problems that are associated with each.

[Solarod]

KALEMIAS do the same the prefix except for heart rate and urine output

HYPERKALEMIA

• Seizure

• Diarrhea

• Hyperreflxia.

• Tachypnea

• Boborymi

• Irritability

• Agitation

• Restlessness

• Tall pwave

• ST elevated

• URINE OUTPUT- OLIGOURIA.

• HEART RATE- BRADYCARDIA.

• BLOOD PRESSURE-HYPERTENSION

HYPOKALEMIA

• Coma

• Constipation

• Hyporeflexia

• Tachycardia

• Dyspnea

• Paralytic ileus

• Flacicity

• URINE OUTPUT- POLYURIA.

• HEART RATE- TACHYCARDIA.

• BLOOD PRESSURE-HYPOTENSION

[Isabelle49]

Considering the effect hypokalemia has on the heart muscle, causing a decreased output, initially a person may have hypotension. Remember, there is a feedback mechanism for just about every physiological event. Once the brain senses a decreased output, adrenal hormones are released resulting in vasoconstriction and increased heart rate. The increased vasoconstriction would result in hypertension, but remember this is an effect of the feedback mechanism and not a direct effect of hypokalemia. I've been out of school for 32 years, hoping I remembered this correctly.

[OcMurse93]

Considering the effect hypokalemia has on the heart muscle, causing a decreased output, initially a person may have hypotension. Remember, there is a feedback mechanism for just about every physiological event. Once the brain senses a decreased output, adrenal hormones are released resulting in vasoconstriction and increased heart rate. The increased vasoconstriction would result in hypertension, but remember this is an effect of the feedback mechanism and not a direct effect of hypokalemia. I've been out of school for 32 years, hoping I remembered this correctly.

If a regulatory mechanism is compensating for hypotension, it would attempt to bring the blood pressure closer to the set-point (roughly 120/80) as possible. Once that was achieved it would no longer be attempting to raise the blood pressure. You would be more likely to have a bp slightly under baseline than full-blown hypertension.

Additionally, i do not know where the OP is getting the "low potassium = high sodium" from. I am not aware of them having an inverse relationship. So the information given may be incorrect.