Fluids, Electrolytes, and Acid-Base Study Guide

Comprehensive flashcards covering fluid volume deficit, fluid overload, IV fluids, sodium, potassium, calcium, magnesium, and acid-base balance based on lecture notes.

Dehydration Risk Factors (GI Losses)

Vomiting, diarrhea, laxatives, NG suction, and GI losses that contribute to fluid volume deficit.

Central Skin Turgor Assessment Site

A central site is more useful in older adults for assessing skin turgor because hand skin loses collagen and adipose tissue.

Minimum Urine Output Threshold

The minimum urine output discussed in the lecture is about $30\,\text{mL/hr}$.

Concentration Assessment Labs in Dehydration

CBC, electrolytes, hematocrit (for concentration), and urine specific gravity.

Symptoms of Fluid Volume Deficit

Dry skin and mucous membranes, sunken eyes or dusky appearance, dizziness, hypotension, compensatory tachycardia, decreased urine output, and weakness or fatigue.

Severe Hypovolemia Progression

Severe hypovolemia can progress to hypovolemic shock, metabolic acidosis, multisystem failure, coma, and death.

Trendelenburg Position in Hypovolemia

A position discussed to bring blood and fluid toward the core during severe fluid volume deficit.

Hemorrhage Rehydration Intervention

Hemorrhage requires blood replacement in addition to fluid management.

Average Adult Daily Fluid Intake Goal

An average healthy adult goal stated by the instructor is about $2,300\text{--}2,600\,\text{mL/day}$.

General Recommended Daily Fluid Intake

The instructor often recommends about $2\,\text{L/day}$, except when restrictions are required.

Fluid Restriction Conditions

Conditions such as congestive heart failure (CHF) or kidney disease that require limiting fluid intake.

Diabetes Insipidus in Fluid Volume Deficit

A condition discussed as a higher-risk example leading to fluid volume deficit.

Bowel Preparation Dehydration Risk

Bowel preparation using multiple enemas combined with NPO status, which puts patients at high risk for fluid volume deficit.

High-Dose Furosemide Risk

A high-dose diuretic therapy named as a higher-risk cause for fluid volume deficit.

Skin Changes in Older Adults Affecting Turgor

Loss of collagen and adipose tissue in hand skin, making central sites necessary for accurate turgor testing.

Causes of Fluid Volume Excess

Increased sodium, excessive fluid supplementation beyond body management, heart failure, renal failure, and liver failure.

Heart-Kidney-Lung Relationship

An interconnected organ system relationship where dysfunction in one organ can place stress on the others.

Ascites Mechanism and Respiratory Impact

Fluid buildup in the abdomen due to liver failure that can push against the diaphragm and impair breathing.

Symptoms of Fluid Volume Excess

Peripheral or pitting edema, ascites, and difficulty breathing.

Severe Fluid Overload Complications

Severe overload may lead to heart failure and pulmonary edema.

Electrolyte Dilution Risks in Fluid Overload

Dilution of sodium and potassium during fluid overload can potentially lead to seizures, coma, and death.

Peripheral Edema Physical Interventions

Elevation of the extremity and compression therapy (discussed as extending at least to the knees).

Fluid Removal Rate Precaution

Fluid must not be removed too quickly because large and rapid fluid shifts are dangerous.

Assessment Parameters for Fluid Overload

Heart, lungs, kidneys, edema, respiratory status, blood pressure, I&O, daily weight, and electrolytes.

Diuresis in Fluid Overload

An intervention used when ordered to remove excess body fluid.

Safe Potassium Administration Rule

Potassium must be administered 'low and slow' to prevent complications.

Standard IV Potassium Infusion Rate

An administration rate of $20\,\text{mEq}$ over $1\text{--}2\,\text{hours}$.

Lethal Potassium Administration Route

IV push potassium, which must NEVER be done because rapid administration causes dysrhythmias, cardiac arrest, and death.

IV Potassium Sensation

Intravenous potassium can cause a burning sensation during infusion.

Isotonic Fluid Definition

A fluid with the same ion concentration/osmolarity as body fluid, producing no net water movement into or out of cells and mainly increasing extracellular volume.

Isotonic Fluid Osmolality Range

Osmolality range of $270\text{--}300\,\text{mOsm/kg}$ as stated in the transcript.

Isotonic Fluid Examples

$0.9\%$ normal saline ($0.9\%$ NS) and Lactated Ringer's.

D5W Osmolar Dynamics

D5W is isotonic in the bag, but becomes hypotonic in the body after dextrose is metabolized.

Hypotonic Fluid Definition

A fluid with lower solute concentration outside the cell, causing water to move INTO cells so cells swell and can burst.

Hypotonic Fluid Osmolality Range

Osmolality of less than $270\,\text{mOsm/kg}$ ($<270$).

Hypotonic Fluid Examples

$0.45\%$ NS, $0.33\%$ NS, and $0.25\%$ NS.

Clinical Indications for Hypotonic Fluids

Intracellular dehydration and hypernatremia, used to move water back into the cells.

Hypertonic Fluid Definition

A fluid with higher solute concentration outside the cell, causing water to move OUT of cells so cells shrink.

Hypertonic Fluid Osmolality Range

Osmolality of greater than $300\,\text{mOsm/kg}$ ($>300$).

Hypertonic Fluid Examples

$3\%$ saline and $5\%$ saline.

Clinical Use of Hypertonic Saline

Used cautiously for severe hyponatremia and cerebral edema in closely monitored settings.

Hypertonic Administration Precaution

Must be given slowly because rapid sodium and fluid shifts can cause neurologic complications.

Sodium Primary Function

Primary extracellular cation responsible for extracellular fluid balance and water movement ('water follows sodium').

Normal Serum Sodium Level

Taught as $136\text{--}145\,\text{mEq/L}$, though instructor noted some labs use $135\text{--}145\,\text{mEq/L}$.

Hyponatremia Definition

A serum sodium level of less than $136\,\text{mEq/L}$ ($<136\,\text{mEq/L}$).

Hyponatremia Etiologies

Overhydration/dilution, SIADH, psychotropic medications, psychogenic polydipsia, inadequate salt intake, and fluid/salt imbalance.

Psychotropic Meds Causing Hyponatremia

Antidepressants and antipsychotics.

Symptoms of Hyponatremia

Muscle cramping/weakness, fatigue, falls in older adults, anorexia, nausea/vomiting, and altered mental status/confusion.

Severe Hyponatremia Complications

Severe cases of hyponatremia can cause seizures and coma.

Hyponatremia Intervention Strategy

Correct the underlying cause and correct sodium/fluid imbalance slowly while monitoring, avoiding rapid shifts.

Hypernatremia Definition

A serum sodium level of greater than $145\,\text{mEq/L}$ ($>145\,\text{mEq/L}$).

Hypernatremia Etiologies

Diabetes insipidus, dehydration, fever, vomiting, diarrhea, diaphoresis, extensive exercise/heat exposure, low water intake, excessive sodium intake, Cushing syndrome, and primary aldosteronism.

Symptoms of Hypernatremia

Agitation, thirst, breathlessness, dry/coated tongue, dry mucous membranes, possible edema, and confusion.

Severe Hypernatremia Complications

Severe hypernatremia can cause seizures and coma.

Hypernatremia Treatment Strategy

Replace water to dilute sodium, restrict salt, correct underlying causes, and lower sodium slowly.

Hypernatremia Rapid Correction Risk

Rapid reduction of sodium can cause cerebral edema and brain injury.

Loop Diuretics Sodium and Potassium Effect

Loop diuretics may remove both salt and potassium, requiring close monitoring of electrolytes.

Potassium Primary Function

Major intracellular cation that maintains cardiac conduction rate/force, nerve conduction, muscle function, acid-base balance, and osmotic pressure.

Normal Serum Potassium Level

$3.5\text{--}5.0\,\text{mEq/L}$.

Hypokalemia Definition

A serum potassium level of less than $3.5\,\text{mEq/L}$ ($<3.5\,\text{mEq/L}$).

Causes of Hypokalemia

Diuretics, reduced intake of potassium-rich foods, increased renal excretion, GI/biliary losses, vomiting, loose stools/diarrhea, and skipping prescribed potassium.

Moderate to Severe Hypokalemia Symptoms

Muscle weakness/spasms, tingling/numbness, fatigue, lightheadedness, palpitations, constipation, bradycardia, ventricular dysrhythmias/VT, and cardiac arrest.

Dietary Potassium Sources

Potatoes, fruits/vegetables, bananas, and juices.

Hypokalemia Interventions

Oral potassium supplementation, dietary potassium intake, and IV potassium replacement ($20\,\text{mEq}$ over $1\text{--}2\,\text{hr}$, never IV push) with ECG monitoring.

Hyperkalemia Definition

A serum potassium level of greater than $5.0\,\text{mEq/L}$ ($>5.0\,\text{mEq/L}$).

Causes of Hyperkalemia

Kidney disease/decreased renal excretion, dialysis/renal failure, acidosis, trauma/crush injury with cellular potassium release, and medications.

Symptoms of Hyperkalemia

Muscle weakness, paralysis, nausea, tremors/twitching, numbness/tingling, peaked T waves, dysrhythmias, cardiac arrest, and confusion.

Urgent Pharmacologic Interventions for Hyperkalemia

Dialysis, potassium-lowering medications, diuretics, insulin with dextrose, calcium gluconate, and potassium-binding therapy.

Hyperkalemia Dietary Restrictions

Restrict potassium-containing foods, especially in renal failure (specifically restricting fruits, vegetables, and potatoes).

Trauma Mechanism in Hyperkalemia

Trauma or crush injury causes cellular disruption, releasing intracellular potassium into the bloodstream.

Calcium Primary Functions

Muscle/neuromuscular and cardiac function, bone maintenance, requiring vitamin D for GI absorption.

Normal Serum Calcium Level

$9.0\text{--}10.5\,\text{mg/dL}$.

Causes of Hypocalcemia

Inadequate intake/GI absorption, anorexia, older age, alcohol use, Crohn's disease, severe respiratory alkalosis, acute pancreatitis, and renal failure/CKD.

Renal Failure Link to Low Calcium

Renal failure/CKD leads to reduced active vitamin D production, resulting in decreased calcium absorption.

Chvostek Sign

A clinical finding of facial twitching indicative of neuromuscular excitability in hypocalcemia.

Trousseau Sign

A clinical finding of carpal spasm indicative of neuromuscular excitability in hypocalcemia.

Symptoms of Hypocalcemia

Neuromuscular excitability/twitching, positive Chvostek and Trousseau signs, laryngospasm, difficulty speaking/breathing, bradyarrhythmias, dysrhythmias, and cardiac arrest.

Interventions for Hypocalcemia

Calcium replacement (e.g. Tums/calcium), increased dietary calcium (safest route), IV calcium when needed, telemetry/ECG monitoring, and treating underlying cause.

Causes of Hypercalcemia

Hyperparathyroidism, bone/parathyroid-producing tumors, endocrine disorders, thiazide diuretics, lithium, breast/lung cancer, multiple myeloma, Paget disease, and low phosphate.

Inverse Electrolyte Relationship with Calcium

Inverse relationship between phosphate and calcium (low phosphate is linked to hypercalcemia).

Symptoms of Hypercalcemia

Fatigue, muscle weakness, decreased deep tendon reflexes, constipation, ECG changes, and high blood pressure.

Hypercalcemia Medical Interventions

Fluids to flush calcium through kidneys, diuretics, holding calcium supplements, decreasing dietary calcium, calcitonin, bisphosphonates (Fosamax), corticosteroids, and hemodialysis.

Magnesium Body Functions

Bone/cartilage storage, neuromuscular control/calming effect, skeletal and smooth muscle contraction, GI peristalsis/laxative effect, carbohydrate metabolism/energy, vitamin activation, blood coagulation, cell growth, cardiac smooth muscle regulation/protection against dysrhythmias, and airway relaxation.

Normal Serum Magnesium Level Range

Book range stated as $1.3\text{--}2.0\,\text{mEq/L}$; instructor noted symptoms may begin around $1.8$ and called $1.7\text{--}1.8$ a 'happy place'.

Causes of Hypomagnesemia

Alcohol use/poor nutrition, inadequate GI intake/absorption, chronic diarrhea/frequent stool, Crohn's disease, older adults with low intake, and other GI losses.

Symptoms of Hypomagnesemia

Increased neuromuscular excitability (overlapping with hypocalcemia), muscle problems/cramps, GI/peristaltic effects, dysrhythmia risk, and increased clot risk.

Dietary Sources of Magnesium

Brazil nuts, pumpkin/sunflower seeds, broccoli, spinach, avocado, seafood, cocoa, eggs, and Ensure.

Causes of Hypermagnesemia

Excessive magnesium supplementation/IV, renal failure (especially with Mg antacids/laxatives), dehydration/concentration, DKA, hypercarbia, thyroid disorders, Addison disease, and prolonged magnesium laxative/antacid use.

Symptoms of Hypermagnesemia

Respiratory depression/dyspnea, hypotension, ECG changes, reduced contractility (excessive smooth-muscle relaxation), and increased bleeding/bruising risk.

Hypermagnesemia Management Principles

Stop or reduce magnesium sources, treat the underlying cause, and monitor respiratory, cardiac, and renal status and labs.

Coagulation Risks of Magnesium Imbalance

Low magnesium is linked with increased clot risk, whereas high magnesium is linked with increased bleeding and bruising risk.

Normal Blood pH Range

$7.35\text{--}7.45$ ($<7.35$ is acidotic; $>7.45$ is alkalotic).

Hydrogen Ion Concentration and pH Relationship

Inverse relationship: more hydrogen ions result in a lower pH.

Respiratory and Renal Roles in Acid-Base

$\text{CO}_2$ is treated as an acid and regulated by the lungs; bicarbonate ($\text{HCO}_3^-$) is treated as a base and regulated by the kidneys along with hydrogen excretion.

Arterial Blood Gas (ABG) Sampling Site

Key lab assessment usually drawn from the radial artery by specially trained personnel.

Acidosis and Potassium Relationship

Acidosis is explicitly linked with hyperkalemia because hydrogen and potassium ions compete for cellular space.

Metabolic Acidosis Definition and Causes

Acidotic pH with a metabolic/bicarbonate problem, caused by DKA/ketone buildup, starvation, kidney dysfunction/ESRD, diarrhea, and severe dehydration/hypovolemia.

Metabolic Acidosis Encephalopathy Symptom

Altered mental status and confusion associated with metabolic encephalopathy.

Respiratory Acidosis Cause and Kidney Compensation

Acidotic pH caused by retaining $\text{CO}_2$ (e.g. COPD); compensated by kidneys producing/retaining $\text{HCO}_3^-$ and excreting hydrogen ions.

Respiratory Alkalosis Cause and Calcium Link

Alkalotic pH caused by low $\text{CO}_2$ (e.g. hyperventilation or mechanical ventilation); severe respiratory alkalosis is associated with hypocalcemia.