ACID – BASE BALANCEACID – BASE BALANCE

HOMEOSTASISHOMEOSTASIS

Relative [ ] of hydrogen ionsRelative [ ] of hydrogen ions

pH – potential hydrogenpH – potential hydrogen

Normal pH: 7.35 – 7.45Normal pH: 7.35 – 7.45

<7.35 is acidosis<7.35 is acidosis

>7.45 is alkalosis>7.45 is alkalosis

Deviation of 0.4 in either direction Deviation of 0.4 in either direction can be fatalcan be fatal

ACIDOSISACIDOSISMetabolic AcidosisMetabolic Acidosis

Excessive blood acidity or loss of Excessive blood acidity or loss of bicarbonatebicarbonateCausesCauses

ingestion of something that is or ingestion of something that is or can can be metabolized to an acidbe metabolized to an acid

such as…..such as…..

Wood alcoholWood alcohol

AntifreezeAntifreeze

Large doses of ASALarge doses of ASA

Abnormal metabolismAbnormal metabolism

Advanced stages of shockAdvanced stages of shock

Poorly controlled IDDMPoorly controlled IDDM

Normal levels of acid if kidneys aren’t Normal levels of acid if kidneys aren’t functioning normallyfunctioning normally

SymptomsSymptoms

Mild metabolic acidosis may have no sx.Mild metabolic acidosis may have no sx.

Usually experiencesUsually experiences

nauseanausea

vomitingvomiting

fatiguefatigue

Breathing becomes deeper and slightly Breathing becomes deeper and slightly fasterfaster

As acidosis worsens:As acidosis worsens:

Extremely weak and drowsyExtremely weak and drowsyMay feel confusedMay feel confusedIncreasingly nauseatedIncreasingly nauseatedEventually b/p can fall leading to shock, Eventually b/p can fall leading to shock, coma, or deathcoma, or death

Treatment:Treatment:Depends primarily on the causeDepends primarily on the cause

insulininsulinremoving toxic substancesremoving toxic substances

RESPIRATORY ACIDOSISRESPIRATORY ACIDOSIS

Build up of CO2 in the blood from Build up of CO2 in the blood from poor lung function or slow breathingpoor lung function or slow breathing

Blood becomes acidic -> pH drops Blood becomes acidic -> pH drops respiratory center in the brain respiratory center in the brain stimulates faster and deeper stimulates faster and deeper breathingbreathing

Develops when…….Develops when…….

Develops when the lungs do not expel Develops when the lungs do not expel CO2 adequately….such asCO2 adequately….such as

EmphysemaEmphysema

Chronic bronchitisChronic bronchitis

Severe pneumoniaSevere pneumonia

Pulmonary edemaPulmonary edema

AsthmaAsthma

Diseases of the nerves or muscles of Diseases of the nerves or muscles of the chestthe chest

If overly sedated from narcotics and If overly sedated from narcotics and strong sleeping medications that strong sleeping medications that slow respirationsslow respirations

Symptoms: Symptoms:

First symptom may be headache and First symptom may be headache and drowsinessdrowsiness

Drowsiness may progress to stupor Drowsiness may progress to stupor or comaor coma

ABGsABGs

Treatment…..Treatment…..

Aims at improving function of the Aims at improving function of the lungslungs

i.e. drugs to improve breathingi.e. drugs to improve breathing

If acidosis is mild, IV fluid may be all If acidosis is mild, IV fluid may be all that is neededthat is needed

If severe; HCO3- (provides only If severe; HCO3- (provides only temporary relief and may cause harm temporary relief and may cause harm by overloading the body with Na+ and by overloading the body with Na+ and H2OH2O

TreatmentTreatment

Slow down rateSlow down rate

Pain reliefPain relief

Other facts to ponder………….Other facts to ponder………….

J:\Class Presentations\BA Acid Base J:\Class Presentations\BA Acid Base Disturbances.docDisturbances.doc

Life essential functions like K+ and Life essential functions like K+ and Na+ channels are inactivated by Na+ channels are inactivated by acidosisacidosisA habitually acid pH can directly cause A habitually acid pH can directly cause immediate weight gainimmediate weight gainFasting and dieting are known acid Fasting and dieting are known acid producing conditionsproducing conditionsOne way the body compensates is to One way the body compensates is to deposit excess acid into tissues and deposit excess acid into tissues and jointsjoints

Acid producing foods create excess Acid producing foods create excess mucus, which congests the system mucus, which congests the system and block oxygen from enteringand block oxygen from entering

ALKALOSISALKALOSIS

Overabundance of bicarbonate in the Overabundance of bicarbonate in the bloodblood

Loss of acid from the bloodLoss of acid from the blood

Respiratory AlkalosisRespiratory AlkalosisLow levels of CO2 in the blood that results Low levels of CO2 in the blood that results from rapid or deep breathingfrom rapid or deep breathingHyperventilationHyperventilation

anxietyanxietycirrhosiscirrhosislow levels of oxygen in the bloodlow levels of oxygen in the bloodfeverfeverASA overdoseASA overdose

METABOLIC ACIDOSISMETABOLIC ACIDOSISBody looses too much acidsBody looses too much acidsGain too much baseGain too much base

stomach acid is lost during periods of stomach acid is lost during periods of prolonged vomitingprolonged vomiting

excessive loss of Na+ or K+ affects excessive loss of Na+ or K+ affects the the kidney’s ability to control the kidney’s ability to control the

blood’s acid-base balanceblood’s acid-base balanceloss of K+ - use of diuretics or loss of K+ - use of diuretics or

corticosteroidscorticosteroids

CorticosteroidsCorticosteroidsSteroid hormonesSteroid hormonesSynthesized from cholesterolSynthesized from cholesterolInvolved in stress response, immune Involved in stress response, immune response, regulation of inflammation, response, regulation of inflammation, carbohydrate metabolism, protein carbohydrate metabolism, protein catabolises blood electrolyte level catabolises blood electrolyte level and behaviorand behavior

Catabolism: breaks down molecules Catabolism: breaks down molecules into smaller units and releases into smaller units and releases energyenergy

Alkalosis may cause:Alkalosis may cause:IrritabilityIrritabilityMuscle twitchingMuscle twitchingMuscle crampsMuscle crampsIf severe, prolonged contraction and If severe, prolonged contraction and spasms of muscle (tetnaory)spasms of muscle (tetnaory)

TreatmentTreatment

MetabolicMetabolic

Replacing H2O, Na+, and K+ while Replacing H2O, Na+, and K+ while treating underlying causetreating underlying cause

Next: …………..Next: …………..

FLUIDS AND FLUIDS AND ELECTROLYTYESELECTROLYTYES

WaterWater60% total body weight60% total body weightDistributed into various compartments, Distributed into various compartments, separated by cell membranesseparated by cell membranesLargest compartment is intracellular Largest compartment is intracellular environmentenvironment

ICFICFAll the fluid found inside body cellsAll the fluid found inside body cells

75% of all water is found within this 75% of all water is found within this compartmentcompartment

Extracellular compartmentExtracellular compartment

2 divisions2 divisions

Intravascular fluid Intravascular fluid

Outside the cells and within the Outside the cells and within the circulatory system. Essentially the circulatory system. Essentially the same as the blood plasmasame as the blood plasma

Interstitial fluidInterstitial fluid

Outside the cell membranes, not Outside the cell membranes, not within the circulatory systemwithin the circulatory system

TBWTBW

Infants – 75-80%Infants – 75-80%

Infants have less fat. Fat does not Infants have less fat. Fat does not absorb water. Less fat, more water absorb water. Less fat, more water

Water is essential for high rates of Water is essential for high rates of metabolism necessary to promote growthmetabolism necessary to promote growthWith ageWith age

Loss of muscle mass inc. % of fat Loss of muscle mass inc. % of fat Body’s decreasing ability to regulate fluid Body’s decreasing ability to regulate fluid levels lower TBW to 45-55%levels lower TBW to 45-55%

Elderly and very young are at high risk for Elderly and very young are at high risk for dehydration and disorders related to to dehydration and disorders related to to electrolyte imbalanceselectrolyte imbalances

ELECTROLYTESELECTROLYTES

Dissociate in electronically charged Dissociate in electronically charged particles when placed into waterparticles when placed into water

ionsions

CationsCations + charge+ charge

AnionsAnions - charge- charge

CationsCations

Na+Na+

Most prevalent in extracellular fluidMost prevalent in extracellular fluid

Plays major role in distribution of Plays major role in distribution of waterwater

Important in the transmission of Important in the transmission of nervous impulsesnervous impulses

K+K+

Intracellular fluidIntracellular fluid

Transmission of electrical impulsesTransmission of electrical impulses

Ca++Ca++

Major role in muscle contractionMajor role in muscle contraction

Nervous impulse transmissionNervous impulse transmission

Mg++Mg++Necessary for several biochemical Necessary for several biochemical processes (over 300)processes (over 300)Prevents over excitability of musclesPrevents over excitability of muscles½ found in bone½ found in bone½ found predominantly inside cells of ½ found predominantly inside cells of tissues and organstissues and organsHelps maintain normal nerve and muscle Helps maintain normal nerve and muscle functionfunction

Regulates heart rhythmRegulates heart rhythm

Supports healthy immune systemSupports healthy immune system

Keeps bones strongKeeps bones strong

Helps regulate blood sugar levelsHelps regulate blood sugar levels

Promotes normal blood pressurePromotes normal blood pressure

Known to be involved in protein Known to be involved in protein synthesis and metabolismsynthesis and metabolism

ANIONSANIONS

Cl-Cl-

Plays a major role in fluid balance Plays a major role in fluid balance and renal functionand renal function

HCO3-HCO3-

Principal bufferPrincipal buffer

PhosphatePhosphate

HPO4-HPO4-

Body energy storesBody energy stores

Closely associated with Mg++ in Closely associated with Mg++ in renal functionrenal function

Acts as a buffer primarily in the Acts as a buffer primarily in the intracellular spaceintracellular space

OSMOSIS AND DIFFUSIONOSMOSIS AND DIFFUSION

IsotonicIsotonic

When solutions on opposite sides of a When solutions on opposite sides of a semipermiable membrane are equal semipermiable membrane are equal in [ ]in [ ]

> on one side – hypertonic> on one side – hypertonic

< on one side – hypotonic< on one side – hypotonic

Difference in [ ] – osmotic gradientDifference in [ ] – osmotic gradient

HomeostasisHomeostasis

The tendency to keep the balance of The tendency to keep the balance of waterwater

electrolytes are = on both sides of electrolytes are = on both sides of the the membrane.membrane.

DiffusionDiffusion

Movement from an area of higher [ ] to Movement from an area of higher [ ] to lower [ ] and does not require energy lower [ ] and does not require energy

OsmosisOsmosis

The passage of any solvent usually water The passage of any solvent usually water through a membranethrough a membrane

Active TransportActive Transport

Movement of a substance across the cell Movement of a substance across the cell membrane against the osmotic gradient or membrane against the osmotic gradient or toward the side that already has more of toward the side that already has more of the substance; requires an expenditure of the substance; requires an expenditure of energyenergy

Facilitated diffusionFacilitated diffusion

Diffusion of a substance such as Diffusion of a substance such as glucose that requires the assistance glucose that requires the assistance of a helper or carrier proteinof a helper or carrier protein

FLUIDSFLUIDSCOLLOIDSCOLLOIDS

Contain large proteinsContain large proteinsCannot pass through a capillary Cannot pass through a capillary membranemembraneRemains in the circulatory systemRemains in the circulatory systemIncreases volume of blood and fluid Increases volume of blood and fluid contained within the blood vesselscontained within the blood vessels

CRYSTALLOIDCRYSTALLOIDContain electrolytes and waterContain electrolytes and water

Tonicity: number of particles per unit Tonicity: number of particles per unit volumevolume

IsotonicIsotonicTonicity equal to blood plasmaTonicity equal to blood plasmaWill not cause a significant fluid or Will not cause a significant fluid or electrolyte shiftelectrolyte shift

HYPERTONICHYPERTONIC

Higher solute [ ] that the cellsHigher solute [ ] that the cells

Causes fluid shift out of intracellular Causes fluid shift out of intracellular compartment into extracellualar compartment into extracellualar compartmentcompartment

HYPOTONICHYPOTONIC

Lower solute [ ] than the cellsLower solute [ ] than the cells

Movement extracellular Movement extracellular intracellularintracellular

ABGsABGs

Determine pH but also to differentiate Determine pH but also to differentiate respiratory / metabolic acidosis / alkalosisrespiratory / metabolic acidosis / alkalosis

NormsNorms

pHpH 7.35 7.35 - 7.45- 7.45

PaCO2PaCO2 3535 - 45- 45

PaO2PaO2 greater than 80greater than 80

HCO3-HCO3- 2222 - 28- 28

PaCO2PaCO2

Amount of CO2 dissolved in arterial Amount of CO2 dissolved in arterial bloodblood

PaO2 amount of oxygen dissolved in PaO2 amount of oxygen dissolved in arterial bloodarterial blood

HCO3 amount of bicarbonate HCO3 amount of bicarbonate

InterpretationInterpretation

(R)espirtory (O)pposite, (M)etabolic (R)espirtory (O)pposite, (M)etabolic (E)qual(E)qual

If the pH is opposite the PaCO2 (high If the pH is opposite the PaCO2 (high or low) then it’s respiratory if the pH or low) then it’s respiratory if the pH is equal to the HCO3, it is metabolicis equal to the HCO3, it is metabolic

Problem #1Problem #1

pHpH 7.307.30

PaCO2PaCO2 5050

HCO3HCO3 2626

PaO2PaO2 6060

Acidosis or Alkalosis?Acidosis or Alkalosis?

Metabolic or Respiratory?Metabolic or Respiratory?

Answer………Answer………

Respiratory AcidosisRespiratory Acidosis

Why?Why?

pH is high indicating AcidosispH is high indicating Acidosis

pH is low; PaCO2 is high {opposite} pH is low; PaCO2 is high {opposite} indicating this is respiratoryindicating this is respiratory

Problem #2Problem #2

pHpH 7.507.50

PaCO2PaCO2 4343

HCO3HCO3 4545

PaO2PaO2 8080

Acidosis or Alkalosis?Acidosis or Alkalosis?

Metabolic or Respiratory?Metabolic or Respiratory?

Answer………Answer………

Metabolic AlkalosisMetabolic Alkalosis

Why?Why?

pH is high indicating alkalosispH is high indicating alkalosis

pH high; HCO3- high {equal}pH high; HCO3- high {equal}

Indicating this is metabolicIndicating this is metabolic

METABOLIC ACIDOSISMETABOLIC ACIDOSIS