Acid-Base Balance KNH 413. Acid-Base Balance Acids Donate or give up H+ ions Rise in pH as a result! Nonvolatile acids or fixed acids CO2 indirect measure.

Acid-Base Balance

KNH 413

Acid-Base Balance

AcidsDonate or give up H+ ions

Rise in pH as a result! Nonvolatile acids or fixed acids

CO2 indirect measure of production of acid b/c of rise of pH

Inorganic acids that occur through metabolism of CHO, protein, lipid

Average amount 50-100 mmol/day Proteins contribute the most Lungs cannot eliminate

Acid-Base Balance

BasesCan accept or receive H+ ions

Ex: bicarbonate Bicarbonate HCO3

Kidneys provide primary regulation of acid base balance

Dialysis patients deal with this on a weekly basis

Acid-Base Balance

pHAcidosis

Accumulation of acid or loss of base

Acidemia (*main concern)pH < 7.35 (stomach acid)

AlkalosisAccumulation of base or loss of acid

AlkalemiapH > 7.45 (pancreatic juice & bile)

Regulation of Acid-Base Balance

Chemical buffers-aid in maintaining balance# 1. bicarbonate increases rate and depth of

breathing b/c increases the amount of CO2 production

Respiratory regulation—to excrete more CO2

Kidney regulation—work to reabsorb more bicarbonate if in an acidodic condition

Regulation of Acid-Base Balance

Respiratory regulatory control:

Change in respiration rate

Depth of breathing

Release or retention of CO2

Regulation of Acid-Base Balance

Renal regulatory controlControl of HCO3 (bicarbonate) by the kidneys that is

excreted Increased or decreased bicarbonate absorption

based on needFormation of dibasic phosphate and sulfur in the

urine Accepts H+

Regulation of Acid-Base Balance

Electrolyte Balance 1. Blood 2. Urine 3. ?

Hydrogen and bicarbonate both electrolytesOther electrolytes affected to maintain

electroneutralityPotassium, chloride, sodium—constantly looking at

these blood values and altering them if necessary

Acid-Base Disorders4 major types

Respiratory acidosis: lower pH, higher plasma bicarbonate, increased CO2 production Trying to excrete more hydrogen to regulate this

Respiratory alkalosis: higher pH, lower plasma bicarbonate, decreased CO2 production

Metabolic acidosis: most common; lower pH, decreased plasma bicarbonate, decreased CO2 Hyperventilation situation; hydrogen being excreted at a

higher level

Metabolic alkalosis: increased pH, increased plasma bicarbonate, increased CO2 production Hypoventilation

Acid-Base Disorders

Respiratory acidosisExcess acid in blood secondary to carbon dioxide

retentionHypercapnia—too much CO2 in the bloodCommon causes d/t respiratory dysfunction – renal regulatory

systems compensate

Acid-Base Disorders

Respiratory acidosisLabs

Decreased pH, elevated pCO3

Slightly elevated bicarbonate Increase in serum Ca, K, Cl

Hypoxemia—inability of oxygen to flow throughout the blood

Restlessness, apprehension, lethargy, muscle twitching, tremors, convulsions, coma

Acid-Base Disorders

Respiratory acidosis

Treatment

Correct underlying condition Increase oxygenation—increasing or decreasing

ventilation Mechanical ventilation

Acid-Base Disorders

Respiratory alkalosis—hyperventilation Relative excess amount of base d/t reduction of CO2

HyperventilationCommon causes - see Table 9.6Shift of acid from ICF to ECF Bicarbonate moved into cells in exchange for

chloride – renal compensation

Acid-Base Disorders

Respiratory alkalosispH > 7.45 Plasma HCO3 low in chronic, PaCO3 low in acute

Cardiac, CNS, respiratory symptomsTreat underlying causeCorrection of hypoxia

Acid-Base Disorders

Metabolic Acidosis All types not caused by excessive CO2

Common causes **Diarrhea most common cause

d/t excessive loss of bicarbonate – bicarbonate-carbonic acid buffer system is stimulated

Fistula drainage may occur

© 2007 Thomson - Wadsworth

Acid-Base Disorders

Metabolic Acidosis Kussmaul breathing—deep labored breathing

Common in DKA

Cardiac and neurological—insult to heart/neurological as a result of being acidotic (not the norm)

Treat underlying cause Raise pH to safe level – not too quickly

Acid-Base Disorders

Metabolic Alkalosis—RARE Excess amount of base (too much acetate in

solution) Fluid imbalance – with volume decrease Without fluid imbalance – without volume

decrease Common causes Underlying event determines pathophysiology

Assessment of Acid-Base Disorders

© 2007 Thomson - Wadsworth