Acid, Base, Electrolytes

Balance and Alterations

Fluid Compartments

Fluid Compartments:20 – 40 – 60 Rule

Fluid Movement

Water and Electrolyte Balance Input = output Hormones

• Na+ / K+• Renin

• Aldosterone

• ANP

• Reproductive Hormones

• GCC

• Ca++ / Mg++• Calcitonin

• PTH

• H2O• ADH

Anions follows passively• Cl-

• HCO3-

• PO4=

Water Intake Loss

• Normal

• Abnormal Osmosis Hormonal control Capillary Dynamics

• CHP

• COP

• IHP

• IOP

Osmosis

Capillary Dynamics

Capillary Pressures

Fluid Shift to third space

Edema Effusion Transudate

• Low cell

• Low protein Exudate

• Types: Nonseptic, Septic

• Contents

• High cell

• High protein

Edema Causes

• Obstruction• Overload• Inflammation• hypoalbuminemia

Vessels• Angioedema• Lymphedema

Types• Localized

• Pitting• Weeping• Dependent

• Generalized

Pulmonary Edema

Pleural Effusion

Terminology

Isotonic• Hypovolemia

• Hypervolemia

Hypertonic• Hyperosmolar

Hypotonic• Hypo-osmolar

Functions of electrolytes

Electrolyte Fluid Composition

Hormones that regulate Electrolytes

Aldosterone ANP PTH Cacitriol Calcitonin

Cations

+ charge Location Function Hormonal Controls Alterations

• Hypo-

• Hyper-

Hyponatremia

< 135 mEq/L Etiology

• Decreased Na+ (diet)

• Increased H20

• Diuretics

• Hiridosis

• Addison’s Disease

• DM

• Diarrhea

• CRF

Clinical Signs• H20 shift to ICF

• Cells swell

• CNS sensitive• V/D

• Lethargy

• Confusion

• Seizures

• Muscle weakness

Hyponatremia

Hypernatremia

> 147 mEq/l Etiology

• Excessive intake

• Hyperaldosteronism

• Drowning (salt water)

• H20 loss

• DI

• Renal

• Fever / Sweat

• Burns

• Diarrhea

Clinical Signs• Osmotic shrinkage

• CNS sensitive

• Lethargy

• Irritability

• Hemorrhage

• Seizures

• Coma

• Muscle weakness

Hypokalemia

< 3.5 mEq/l Etiology

• Decreased intake

• ANS

• V/D

• Diuretic

• Sweating

• Digitalis

• Insulin excess

Clinical Signs• Decreased RMP

• Heart dysrhythmia• Bradycardia

• AV blocks

• PVCs

• Sphincter weakness

• Delayed cardiac repolarization• ST segment depression

• T decreased/inverted

Hyperkalemia

> 5.5 mEq/l Etiology

• Increased intake

• Insulin deficiency

• Hemolysis

• Hypoxia

• CRF

• Diuretics

• Burns

• Extensive surgeries

Clinical Signs• Inactivate Na+

channels• Muscle weakness

• Muscle paralysis

• paralysis

• Cardiac dysrhythmia• Peaked T wave

• Widened QRS

Hypocalcemia

< 8.5 mg/dL Etiology

• Nutritional deficiency

• Osteoblastic metastasis

• PTH deficiency

• Hyperphosphatemia

• Increased protein binding

• Chelation therapy

Clinical Signs• NMJ irritability

• Muscle Spasm

• Dyspnea

• Seizures

• Colic

• Tetany

• Cardiac Dysrhythmia

Hypercalcemia

> 10.5 mg/dL Etiology

• Cancer

• Hyperparathyroidism

• Bone remodeling

• Increased reanal filtering

Clinical Signs• NMJ decreased

• Fatigue

• Lethargy

• Weakness

• Cardiac dysrhythmia

• Bone loss

• Urolithiasis

Hypomagnesemia

< 1.5 mEq/l Seen with hypokalemia

and hypocalcemia Etiology

• Decreased dietary intake

• GI loss

• Malabsorption

• Maldigestion

• Diarrhea

• CRF

Clinical Signs• Decreased threshold

• Tetany

• Vertigo

• Nystagmus

• Muscle spasms

• hyperreflexia

• Seizures

• Cardiac Dysrhythmia

Hypermagnesemia

> 2.5 mEq/l Etiology

• Excess intake (antacids)

• Decreased renal excretion

• CRF

• Adrenal insufficiency

Clinical Signs• Increased threshold

for depolarization

• Muscle weakness

• Decreased reflexes

• Hypotension

• Decrease Na+ current

• Cardiac dysrhythmia

• Bradycardia

Anions Chloride ECF Alterations

• Hypochloremia• < 95 mEq/L

• Accompanies hyponatremia

• Severe vomiting

• Diuretics

• Hyperchloremia• > 103 mEq/L

• Accompanies hypernatremia

Phosphate ICF, stored in bones Alterations

• Hypophosphatemia• < 2.7 mg/dL

• Antacid use

• Prolonged decrease cam cause Rickets/’Osteomalacia

• Hyperphosphatemia• > 4.5 mg/dL

• Renal failure

• Overuse of laxatives

• Hypoxia

Acid Base Terms Define

• pH• Acid

• Strong• Weak• Volatile : CO2 from CH20 and Fat Metabolism• Nonvolatile: H2SO4, H2PO4 from protein metabolism

• Base• Strong• Weak

• Salt• Buffer

Acid Sources

pH Define

• pH = log (1/[H+])• pH = -log [H3O+]

Water Dissociation• H2O + H2O

H3O+ + OH- Scale Blood values

• Venous• Arterial

Abnormal Values• Acidemia• Alkalemia

pH formula and scale

Acid Base Chart

pH of Solutions

Acid Base Regulation for Balance Systems

• Chemical Buffer Systems• Respiratory System• Renal

Time• Seconds to Minutes• Minutes to Hours• Hours to Days / Weeks

Strength Problems (reference 7.4 as normal average):

• + / - 0.1 changes result in respiratory rate changes• + / - 0.2 to 0.3 changes result in CV and Nervous changes• + / - 0.4 to 0.5 changes result in death

Chemical Buffer Systems

Define 3 types

• Name of System

• Buffer formula or name of chemical

• Location

• Effectiveness [pKa buffer = pH location]

• Why important

pH changes with/without buffers

Bicarbonate Chemical Buffer H2CO3, HCO3- Plasma buffer pK = 6.1 Important:

• Can measure components• pCO2 = 40 mmHg• HCO3- = 24 mM

• Can adjust concentration / ratio of components • HCO3- @ kidneys• CO2 @ lungs

• Recalculate pH of buffer system in ECF using Henderson-Hasselbach• pH = 6.1 + log(24 / 0.03x40)

• pH = 6.1 + log (20/1)• pH = 7.4

Bicarbonate Buffer System

Phosphate Chemical Buffer

H2PO4-, HPO4= ICF, Urine pK = 6.8 Important

• Intracellular buffer• ICF pH = ~ 6.5 – 6.8

• Renal Tubular Fluids• Urine pH ranges 6.0 – 7.0

Protein Chemical Buffer

Proteins• With Histadine: AA contain imidazole ring, pKa = 7.0

• R-COOH R-COO- + H+

• R-NH2 R-NH3+

ICF (hemoglobin), ECF pK = 7.4 Important

• Most numerous chemicals

• Most powerful chemical buffer

Proteins in acid base

Hemoglobin

CO2 transport and RBC buffer

Respiratory for A/B Balance

Occurs in minutes CO2 only Rate changes

Respiratory Controls for Acid /Base balance

Volatile Acid: CO2 pH changes in CSF Respiratory Rate

• Pons

• Medulla Oblongata

Chemoreceptors• pCO2

• pO2

CO2 and pH

Increase CO2• Increase H+

• Decrease pH

Decrease CO2• Decrease H+

• Increase pH

Renal Control for Long Term Acid / Base Balance

Renal processes in A/B balance

Renal Physiology Filtration

• Remove metabolic acids: Ketones, Uric acid

• Filter Base [HCO3-] @ Renal Filtration Membrane

Reabsorption• Base @ PCT• Reverse CO2 equation to

create HCO3- Secretion

• H+ @ PCT, late DCT and Cortical CD

• CO2 equation to create H+ for secretion

Renal Mechanisms for A/B

Renal Ion Exchanges

Na+ / K+ antiporter Na+ / H+ antiporter Na+ / HCO3- cotrans H+ / K+ ATPase H+ ATPase Cl- / HCO3-

exchanger

Renal Buffer Mechanisms

Normal Acid Base Values

Respiratory and Renal Balance

Acid-Base Problems

Acidosis• State of excess H+

Acidemia• Blood pH < 7.35

Alkalosis• State of excess HCO3-

Alkalemia• Blood pH >7.45

Classifying Respiratory Acid Base Problems (pCO2 changes)

Respiratory Acidosis• Respiratory Rate Decreases

• Any Respiratory Disease

• Obstruction

• Pneumonia

• Gas exchange / transport problems

• Respiratory Membrane

• RBC / Hemoglobin

Respiratory Alkalosis• Respiratory Rate Increases

Classifying Metabolic Acid Base Balance Problems (H+/ HCO3-) Systems

• Renal • Endocrine• GI• Cardiovascular / Fluid administration

Metabolic Acidosis• Retain Acid• Lose Base

Metabolic Alkalosis• Retain Base• Lose Acid

Other System diseases in Metabolic Acid/Base Problems

GI • Vomiting

• Diarrhea

• Medications : Antacids Endocrine

• DM

• Hyperaldosteronism Metabolism

• Increase acid production

Ketones

Compensation

Adjustments for Acid/Base Balance

Imbalance• Respiratory Acidosis

• Incr pCO2

• Respiratory Alkalosis• Decr pCO2

• Metabolic Acidosis• Decr HCO3-

• Incr H+

• Metabolic Alkalosis• Incr HCO3-

• Decr H+

Compensation• Increase renal acid

excretion, Incr HCO3-

• Decrease renal acid excretion, decr HCO3-

• Hyperventilate to lower pCO2

• Hypoventilate to increase pCO2

Summary for A/B Balance

Questions?

Water and electrolytes