Acid Base Balance

Acids are

substances that release hydrogen when disolved in water

Acid base balances can alter

respirationmetabolismfunction of the CNS


excess of hydrogen ions

acidosis ph

arterial pH less than 7.35

bases are

substances that nind hydrogen ions when in water


excess of base (bicarbonate)

alkalosis pH

greater than 7.45

acidosis seen in pts with

pneumoniadehydrationinfectionrenal disease

alkalosis seen in pts with

overhydrationheart failurethazide and loop diuretics digoxin insulinchemotherapy

respiratory rate increase will cause a drop in

CO2 and pH

decrease in respiration rate will cause a decrease in

CO2 and pH

Kidney's movement of HCO2

when pH is high, HCO2 is excreted in urinewhen pH is low, HCO2 is reabsorbed

When HCO2 is reabsorbed it binds with

phosphate in the urine to make acid (H2PO4)

Ammonium is formed by

the kidneys when amino acids bind with H to form ammonium and is excreted in urine

alkalosis is a excess of


Acidic means

more acid than basemore hydrogen ionslower pH(kicking Down the pH) AciDosis

Alkaline means

more acid than basefewer hydrogen ionshigher pH(Kicking Up the pH) Alkalosis

normal pH range

7.40,5 up and 0.5 down

pCO2 normal range

405 up and 5 down

HCO3 normal range

242up and 2down

pO2 normal range

9010up and 10 down

pH less than 6.8


pH greater than 7.8


ph lowers if

hydrogen level concentration increasesbicarbonate level decreases

3 physiologic systems act interdependently to maintain a normal serum pH

buffering of excess acid or base by blood buffer systemsexcretion of acid by the lungsexcretion of acid or regeneration of base by the kidneys

chemical buffers

act immediately to protect tissues and cellscombinds with acids or bases immediately to neutralizelocated in ICF and ECFcontrol H ions by either absorbing them to make an acid or releasing them to make a base


only works for respiratory acidiosisresp system changes hydrogen ions concentration by changing respiratory rate and depthmore carbonic acid is formed with decrease respiration

respirations will increase if

more CO2 needs to be breathed off

Buffers are found in

bloodICFinterstitial fluid

main buffers


bicarbonate buffers use a week

acid or week base as carbonic acid or bicarb with a strong base or strong acid as HCL to make less strong base or acid

protien buffers

most abundant in the bodyhemoglobin and other protiensneutralizes acid and base

in RBCs hemoglobin will bind with what to act as a buffer


PaCO2 is

measures dissolved carbon dioxideregulate to amount produce in cellsregulate by lungsrelated to alvolar ventilation

an increase in ventilation will cause what in PaCO2


a decrease in ventilation will cause a what in PaCO2


CO2 combinds with what to make carbonic acid


increased levels of carbonic acid will cause a what in pH


what area of the brain has chemoreceptors that regulate rate and depth of breathing to control CO2


the more CO2 that is lost the more

carbonic acid is made

alveoli hypoventilation occurs

either from decreaseed respiration of inadequate gas exchange

respiratory acidosis

caused by the under elimination of hyddrogen ions causing retention of carbon dioxide in the bodyresulting in increased production of carbonic acid

four causes of respiratiory acidosis

airway onbstructioninterference with capillary diffusionpoor chest expansionrespiratory depression

In cronic respiratory acidosis as with COPD the kidneys have had time to compensate so the pH may be

within normal range

Respiratory depression

anesthesisnarcotichead traumacardiac arrestinjury to chest, airway, lungs

As brain cells become acidotic mental stauts

changes are noticeddisorientationdepressionweaknessstuporwarm and moist mucus membranes

Respirtory acidosis oxygen and ECG changes


Respiratory acidosis cases chemical changes

decrease in pHincrease in PaCO2increase in HCO2

Respiratory acidiosis casues

headachemental status changedecreased level of conciousnessmuscle twitchingelectrolyte changeK and Ca

interventions of respiratory acidosis

safety measuresassist with positioningmonitor IandOadmisister fluids as orderdadminister oxygen and medication as orderdmonitor ABGs

Respiratory alkalidosis

PaCO2 goes down and pH up

respiratory alkalidosis causes hyperventilation resulting in

retain oxygen blow off CO2feversailcylate intoxication (early ASA OD)CNS traumaexcess mechanical ventilation with O2>CO2

Respiratory alkalosis skin, oxygen, ecg problems

warm flush mucous membranessweating and diaphoresisRAPID, SHALLOW BREATHING (compensating)palpitations

Respiratory alkaladosis biochemical effects

increase in pHdecrease in PaCO2

Respiratory Alkalidosis causes these problems

anorexia (to rid acid) N/Vabd painweaknessaltered mental stausdecreased LOCdysthrythmiabradycardiatetany convulsions

Respiratory alkalosis cognitive and sensory

hyperactive reflexestetanypositive chvostek's signpositve trousseau signvertigounconciousness

causes of respiratory alkalosis

hyperventlationearly PEfeveranxitey (blows of CO2)

Metabolic alkalosis causes

loss of gastric juicepotassium wasting diuretic (loss of H)misuse of antacidstoo much bicard or loose acidhigh carb diethyperkalemia hypercalcemia

metabolic alkalosis

hypokalemia occurs as K is exchanged for H ions in the cell

Lungs will begin to retain CO2 to lower pH when

metabolic alkalosisclinical manifestationhypotensiontachycardiaconfusiondecreased LOChyperreflexiatetanydysthrhymiaseizuresrespiratory failureas pH increases , respiratry failure dysthrhythmia, seizure coma occur

Acidosis caused by

respiratory hypoventilationpulmonary edemadrug overdoseairway obstructionchest traumaCOPD

Metabolic acidosis causes

asprin overdosesepsisdiarrheaRenal Failure (K increase)fasting, DKA, Salicylates poisoning, diarrhea, interstiatl suction, Pancreatic damage, renal impairment, saline infusions, bicarb is lost

hyperventilation is a cardinal sign of

metabolic acidosis

fluid is lost>

acidity increases>lowering pH

to correct metabolic acidosis the lungs blow off

CO2 to increase pH (promoting alkaline HCO3)

metabolic acidosis regulaters do what

meausres bicarbonate ionregulated by kidneysacts as buffer in acid base systemkidneys have slower response to adjust pH than lungs

if blood has more base and less acid then

kidneys hold hydrogen and excrete bicarb

respiratory helps to regulate metabolic imbalances; lack of bicarb causes acidosis

lungs will increase rate of breathing and blow off CO2, thus raising pH

An excess of bicarb causes alkalosis; lungs will decrease rate of breathing and retain CO2

thus lowering the pH

acid base balance exists when

the body produces acids or bases equal to the rate they are excretedmetabolic processes maintain a steady balance between acids and bases for optimal functioning of cells

ratio of acids to base

20 base to 1part acid

if acids increase or base decreases then

scale tips toward acidic side lowering pH

if acid decreases or base increases then

tips to base side and pH increases

Volatile acid is in what system

respiratory, can be excreted as a gas

Nonvolatile acid

renal, must be metabolized or excreted from the body in a water form

drawing sites for ABGs


things that will alter the result of ABGs

air bubble in syrnge may alter levelvenous blood will alter resultscup of ice immediatelyhold pressure for 5 min

increase or decrease in PaCO2 levels shows that what has occured

decrease, hyperventilation (blows off)increase, hypoventilation (retained)


Respiratory (PaCO2 and pH)OpositeMetabolic (HCO3 and pH)Equal

is there a normal decline in older adults

yes of PaCO2

hypoxemia may cause

hyperventilation resulting in resiratory alkalosis

oxygen saturation

the point at which hemoglobin is saturated by oxygen

oxygen saturation can be effected by

changes in temperaturechanges in pHchanges in PaCO2when PaCO2 falls below 60 there is a large drop in saturation

serum bicarbonate HCO3

the major renal componet of acid base balance is excreted and reproduced by the kidneys to maintain a normal acid base environment

bicarbonate reflects the renal systems ability to

compensate for changes in the pHpH is high (basic) HCO3 is excreted by the kidneypH is low (acid) HCO2 is reabsorbed by kidneys, H, ammonia, and protien excreted by diney

How to read ABGs

evaluate PaO2 and SaO2evaluate pHevaluate PaCO2evaluate HCO3evaluate in respiratory or metabolicevaluate compensationpull it all together

high PaCO2

hypercapniabreathing slowly/shallow/poor expiratory effort and not blowing off CO2


body's attempt to maintain normal pHrespiratory system controls PaCO2renal system controls HCO3if one system changes: other system changes to compensate

if compensation is metabolic then all go

up or downpH, HCO3, PCO2