Fluid & Electrolyte Balance, Pharmacology/Drug Responses, Pain Assessment & Management

Water vs Solute

Water is the solvent; particles are the solute.

Electrolytes

Charged ions dissolved in body fluids.

Main fluid compartments

ICF ~25 L; ECF includes plasma (3.5-6 L) and interstitial (10-12 L).

Normal sodium range

136-145 mEq/L.

Normal potassium range

3.5-5.0 mEq/L.

Normal calcium range

9.5-10.5 mg/dL.

Normal magnesium range

1.8-2.6 mEq/L.

Normal osmolarity

270-300 mOsm/L (isotonic).

Aldosterone action

Retains sodium and water; excretes potassium.

ADH action

Retains water only.

BNP/Natriuretic peptides

Promote sodium and water excretion.

RAAS purpose

Increases blood pressure and blood volume.

Best indicator of fluid changes

Daily weight (1 lb = 500 mL fluid).

Dehydration assessment

Low BP, high HR, dry mucosa, poor turgor.

Fluid overload signs

Edema, crackles, SOB, bounding pulses.

Treatment for fluid overload

Diuretics, sodium/fluid restriction, daily weights.

Hyponatremia symptoms

Confusion, seizures, muscle weakness, increased GI motility.

Hyponatremia treatment

3% saline if severe; fluid restriction.

Hypernatremia symptoms

Confusion, twitching, decreased DTRs, orthostatic hypotension.

Hypernatremia treatment

Hypotonic fluids; diuretics for excess sodium.

Hypokalemia signs

Weak pulses, dysrhythmias, decreased peristalsis.

Safe potassium replacement

NEVER IV push; max rate 10 mEq/hr.

Hyperkalemia causes

Kidney disease, ACE inhibitors, blood transfusions.

Hyperkalemia treatment

Insulin + D50, calcium gluconate, diuretics.

Definition of pain

Pain is whatever the patient says it is.

Acute pain features

Increased vital signs, agitation, restlessness.

Chronic pain features

Fatigue, depression, impaired ADLs.

Somatic pain

Sharp, localized; skin/muscle/bone.

Visceral pain

Poorly localized; cramping or pressure in organs.

Neuropathic pain

Burning, shooting, electrical sensations.

Pain assessment tools

NRS, Faces, Verbal Descriptors.

Pain location types

Localized, projected, referred, radiating.

Older adult pain tools

PAINAD; checklist for seniors with limited communication.

Nonpharmacologic pain relief

Heat, cold, massage, distraction, PT, breathing.

Multimodal pain therapy

Using multiple analgesics or methods to improve relief.

Acetaminophen limits

Max 4 g/day; limit to 2 g with liver disease.

NSAID risks

GI bleeding, renal injury, increased cardiovascular risk.

Opioid examples

Morphine, hydromorphone, fentanyl, oxycodone.

Common opioid side effects

Respiratory depression, constipation, sedation.

Naloxone use

Reverses opioid overdose.

Opioids to avoid

Meperidine, codeine.

Adjuvant analgesics

Gabapentin, pregabalin, TCAs, SNRIs, muscle relaxants.

PCA safety rule

ONLY the patient pushes the PCA button.

Ideal drug properties

Effective, safe, selective.

Pharmacokinetics definition

What the body does to the drug.

Four pharmacokinetic processes

Absorption, distribution, metabolism, excretion.

Pharmacodynamics definition

What the drug does to the body.

Dose-response relationship

More dose → more effect until maximal response.

Factors causing drug variation

Genetics, age, comorbidities, other drugs.

Nursing responsibilities before meds

Right patient, drug, dose, time, route; check contraindications.

Nursing responsibilities after meds

Monitor response and adverse effects; document.

Ways to minimize adverse effects

Assess interactions, teach warnings, know toxicity signs.

Generic vs trade names

Generic preferred; trade names vary between products.

Common drug stem: -pril

ACE inhibitors.

Common drug stem: -sartan

ARBs.

Common drug stem: -olol

Beta blockers.

Common drug stem: -prazole

Proton pump inhibitors.

OTC concerns

May mask symptoms or cause double dosing.