Acid-Base Balance

KNH 413

Acid-Base Balance

Acids- rise in pHDonate or give up H+ ions

Nonvolatile acids or fixed acids 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

Bicarbonate HCO3

Kidneys provide primary regulation

Acid-Base Balance

pHAcidosis

Accumulation of acid or loss of base

AcidemiapH less than 7.35

Alkalosis- rare Accumulation of base or loss of acid

AlkalemiapH greater than 7.45

Regulation of Acid-Base Balance

Chemical buffers- in the middle, maintain the acid base balance, bicarbonate

Respiratory regulation- increase the rate and the depth of your breath CO2 production/excretion is increased

Kidney regulation- reabsorb more bicarbonate if in a acidic 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 control

Control of HCO3 (bicarbonate) by the kidneys

Increased or decreased based on need Formation of dibasic phosphate and sulfur in the

urine Accepts H+

Regulation of Acid-Base Balance

Electrolyte Balance- Work on TPN solution to make sure they are not in acidosis

Hydrogen and bicarbonate both electrolytesOther electrolytes affected to maintain

electroneutralityPotassium, chloride, sodium

Acid-Base Disorders

4 major typesRespiratory acidosis- lower pH, higher plasma,

bicarb, increased CO2 production excretes more H from the kidneys to alter this

Respiratory alkalosis- pH up, bicarb, plasma and CO2 down

Metabolic acidosis- lower pH, decreased plasma, bicarb, CO2

Metabolic alkalosis- increased pH, plasma, bicarb, CO2, kidneys increase bicarbonate excretion

Acid-Base Disorders

Respiratory acidosisExcess acid in blood secondary to carbon dioxide

retentionHypercapnia- too much CO2 in the blood, breathing

to compensate that (hyperventilate) Common 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 (lab values)

Hypoxemia- decreased partial pressure in the blood, decreased flow of O2 in the blood

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

Acid-Base Disorders

Respiratory acidosisTreatment

Correct underlying condition bring up the bicarbonate Increase oxygenation Mechanical ventilation

Acid-Base Disorders

Respiratory alkalosis (hyperventilation) CO2 eliminated faster than it can be replaced 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 if they are functioning properly

Acid-Base Disorders

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

Cardiac, CNS, respiratory symptomsTreating underlying cause as a medical teamCorrection 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

© 2007 Thomson - Wadsworth

Acid-Base Disorders

Metabolic Acidosis Kussmaul breathing- deep labored breathing Cardiac and neurological (as a result of being

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

Acid-Base Disorders

Metabolic Alkalosis- RARE, from overuse of base, medically induced

Excess amount of base Fluid imbalance – with volume decrease Without fluid imbalance – without volume

decrease Common causes Underlying event determines pathophysiology-

what is going on to cause them to lose this acid??

Assessment of Acid-Base Disorders

© 2007 Thomson - Wadsworth