Acid-Base Balance PowerPoint Presentation, PPT - DocSlides

Acid-Base Balance PowerPoint Presentation, PPT - DocSlides

2016-02-20 277K 277 0 0

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Janis Rusin APN, MSN, CPNP-AC. Pediatric Nurse Practitioner. Lurie Children’s Transport Team. Objectives. Discuss the mechanisms for maintaining normal acid-base balance. Define respiratory and metabolic acidosis and alkalosis. ID: 224829

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Presentations text content in Acid-Base Balance

Slide1

Acid-Base Balance

Janis Rusin APN, MSN, CPNP-AC

Pediatric Nurse Practitioner

Lurie Children’s Transport Team

Slide2

Objectives

Discuss the mechanisms for maintaining normal acid-base balanceDefine respiratory and metabolic acidosis and alkalosisIdentify the common causes of acid base imbalanceDefine and differentiate between respiratory distress and failureDiscuss interventions on transport for a patient with acid-base imbalance

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Slide3

Acid-Base Balance

The human body must be maintained in a very narrow range of acid-base balanceWe use pH as our measure of acidity or alkalinitypH stands for “power” of hydrogenNormal pH is 7.35-7.45-Not a whole lot of wiggle room!Normal cellular metabolism occurs within this rangeThe 2 major organs responsible for maintaining acid base balance are:The lungs-Respiratory balanceThe kidneys-Metabolic balance

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Slide4

Chemistry Flashback!

An acid is a substance that releases hydrogen ions (when it dissociates)A base is a substance that accepts the hydrogen ionsA buffer is a substance that protects the pH from derangements by binding with hydrogen ionsHA  H+ + A-

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Slide5

The Bicarbonate Buffer System

The bicarbonate buffer system is what we monitor clinically to assess acid base balance This system works in the plasmaRelationship of carbon dioxide (CO2) to bicarbonate (HCO3-)CO2 is the acid and HCO3- is the base

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Slide6

Balancing Act

LungsCO2 is an end product of normal cellular metabolismThe lungs regulate the CO2 level through respirationRapid response-quick fix!The lungs cannot regulate bicarbonate levels

KidneysThe renal tubules reabsorb bicarbonateExcess hydrogen ions are excreted in the urineSlower processThe kidneys cannot regulate CO2 levels

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Slide7

Clinical Applications

Acidosis (blood pH < 7.35)A pathologic condition that causes an increase in the hydrogen ion concentrationAlkalosis (blood pH > 7.45)A pathologic condition that causes a decrease in the hydrogen ion concentrationA simple acid base disorder has just one disturbanceThe respiratory and metabolic systems compensate for each others deficienciesIf there is more than one disturbance, the patient is said to have a mixed acid base disorder

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Slide8

Types of Acid Base Disorders

Metabolic AlkalosisMetabolic AcidosisRespiratory AlkalosisRespiratory Acidosis

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Slide9

Metabolic Alkalosis

An elevation in the serum pH associated with a decrease in hydrogen ion concentration and increase in bicarbonate ion concentrationChloride plays a big role2 main categoriesChloride ResponsiveChloride levels are < 10 mEq/LChloride ResistantChloride levels are > 20 mEq/L

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Slide10

Metabolic Alkalosis

Chloride ResponsiveHydrogen ions are lostVomitingLoss of HCL from stomach contents, as well as Na and KExcessive NG suctioningLoss of both Hydrogen and Chloride ionsThe kidneys retain Na and K instead of H in order to maintain the Na-K pump functionDiureticsPull H2O from the extracellular space which is low in bicarbResults in an increased concentration of bicarbMore bicarb available to bind with HydrogenPost hypercapnia Compensation by kidneys to retain bicarb in presence of hypercapniaMetabolic alkalosis occurs transiently once PaCO2 levels corrected

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Metabolic Alkalosis

Chloride ResistantBicarbonate is retainedHypokalemiaLow serum K causes K to shift out of the cells and H to shift into the cellsExcessive base intakeAntacidsHypertensionAldosterone levels are elevatedResults in Na and H2O retentionHydrogen and excess K are dumped by kidneyK shifts into cells

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Slide12

Metabolic Acidosis

A decrease in pH associated with a low serum bicarbonate concentrationThree primary mechanisms:Bicarbonate is lost form the bodyKidney function is impaired and acid cannot be excreted properlyEndogenous or exogenous addition of acid to the bodyCommon Diagnoses leading to MADiarrheaInsulin Dependent Diabetes Mellitus (IDDM)Lactic Acidosis Poor perfusion and shockRenal Failure

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Metabolic Acidosis

DiarrheaMost common cause of MABicarbonate is lost in excessive stoolThe kidneys are unable to keep up with the lossesPotassium is also lost in the stoolVolume depletion results in aldosterone releaseSodium is retained leading to further loss of KHypokalemia results

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Slide14

Metabolic Acidosis

Diabetic KetoacidosisInsulin deficiency occurs stimulating the release of excess glucagonGlucagon stimulates the release of fatty acids from triglyceridesFatty acids are oxidized in the liver to ketone bodies, beta-hydroxybutrate and aceto-acetic acidThese acids result in MAIn addition, the DKA patient become volume depleted due to excessive urinationShock develops and further exacerbates the acidosis

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Slide15

Metabolic Acidosis

Lactic acidosisHypoxia or poor tissue perfusionCells are forced into anaerobic metabolism producing lactic acidShockExcessive exerciseEthanol toxicityEthanol interferes with gluconeogenesisAnaerobic metabolism

Renal FailureDistal RTAFailure of the distal tubule to properly excrete hydrogen ionsFanconi syndromeFailure of the proximal renal tubule to reabsorb bicarbonate, phosphate and glucoseCauses include:GeneticsMedications such as tetracycline and antiretroviralsLead poisoning

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Slide16

Anion Gap

Calculation that determines the gap between concentrations of positive (cations) and negative (anions) ionsUseful in determining the cause of metabolic acidosisCalculated by:(Na+ + K+) – (HCO3- + Cl-) = 10-12mEq/L

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Slide17

Anion Gap

Normal Anion GapThe loss of bicarbonate is compensated for by the retention of chlorideAlso known as Hyperchloremic Metabolic AcidosisDiarrheaRenal Failure, Proximal RTA

Elevated Anion GapMA due to increased H+ loadMUDPILESMethanolUremiaDKAPropylene GlycolIsoniazid Lactic AcidEthylene Glycol (antifreeze)Salicylates

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Slide18

Respiratory Alkalosis

A condition in which the carbon dioxide content is significantly reduced (hypocapnia)Caused by:HyperventilationOccurs within minutes of onset of hyperventilationPulmonary diseaseCHFHypermetabolic statesFeverAnemaHyperthyroid

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Slide19

Respiratory Acidosis

Occurs when ventilation of CO2 is inadequate and CO2 is retained (hypercapnia)Causes include airway obstruction, respiratory depression, pneumonia, asthma, pulmonary edema, chest traumaThe renal buffer system is not effective for acute RAChronic respiratory acidosis can be well compensated for by the kidneys

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Slide20

So, how do we make the diagnosis?

Arterial Blood Gas-Normal ValuespH (7.35-7.45)PCO2 (35-45)PO2 (80-100)HCO3 (22-26)Base Excess/Deficit (-2 to +2)

Venous Blood Gas-Normal ValuespH (7.31-7.41)PCO2 (40-50)PO2 (35-40)HCO3 (22-26)Base Excess/Deficit (-2 to +2)

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Slide21

Blood Gas Analysis

Step 1: Look at the pH< 7.35 is acidic> 7.45 is alkaloticStep 2: Look at the PCO2<35 is alkalotic> 45 is acidicStep 3: Look at the HCO3< 22 is acidic> 26 is alkalotic

Step 4:Match the pH to either the PCO2 or HCO3 Whichever one goes in the same direction as pH determines the primary disorder Respiratory = CO2Metabolic = HCO3Step 5:Which one goes in the opposite direction of the pH?This is the compensatory systemStep 6: Look at the PO2Determines presence of hypoxia

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Slide22

Blood Gas Analysis

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Normal Values

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HCO322

45PaCO235

Blood Gas Interpretation

pH 7.35-7.45 Acidemia Alkalemia

RespiratoryAcidosis

MetabolicAlkalosis

Metabolic Acidosis

Respiratory

Alkalosis

Slide23

Mixed Acid Base Disorders

When to suspect a mixed acid base disorder:The expected compensatory response does not occurCompensatory response occurs, but level of compensation is inadequate or too extremeWhenever the PCO2 and HCO3 become abnormal in the opposite direction. In simple acid base disorders, the direction of the compensatory response will always be in the same as the direction of the initial abnormal change. pH is normal but PCO2 or HCO3- is abnormalGeneral rule:If the pCO2 is elevated and HCO3 is reduced, then both respiratory and metabolic acidosis are presentIf the pCO2 is reduced and the HCO3 is elevated, then both respiratory and metabolic alkalosis are present

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Slide24

Respiratory Distress

A compensated state in which oxygenation and ventilation are maintainedDefine oxygenation and ventilationHow will the blood gas look?Characterized by any increased work of breathingFlaring, retractions, gruntingWhat is grunting?

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Slide25

Respiratory Failure

Compensatory mechanisms are no longer effectiveInadequate oxygenation and/or ventilation resulting in acidosisAbnormal blood gas with hypercapnia and/or hypoxiaWill begin to see decreasing LOC due to hypercapniaMedical emergency! Must protect airway!Strongly consider intubation

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Slide26

Respiratory Failure-Causes

Pulmonary CausesDiffusion impairmentAtelectasisPneumoniaBronchiolitisAcute lung injuryPulmonary edemaShunting and V/Q mismatch

Non-Pulmonary CausesRespiratory muscle compromise or fatigueImpairment of the nervous systems control of breathingGuillain-BarreMuscular DystrophyCentral hypoventilation syndromeSedativesHead injuryUpper airway obstructions

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Slide27

Indications for intubation

Inability to protect airwayNo cough or gagDecreasing LOCGCS < 8Cardiac or respiratory arrestAcute respiratory acidosisRefractory hypoxemia despite 100% FiO2

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Slide28

Goals of ventilation

Correct acidosisRest the respiratory musclesCorrect hypoxemiaAllows for delivery of high FiO2PEEPImproves cardiac functionDecreases preloadDecreases metabolic demand

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Slide29

Initial Ventilator settings

Volume ControlPressure ControlRateNormal for ageNormal for ageTidal Volume8-10 cc/kgPEEPStart at 5cm H2O and increase as clinically indicatedStart at 5cm H2O and increase as clinically indicatedi-Time1:2(Must increase E-time in obstructive processes to avoid air trapping)Pressure ControlSet pressure to produce adequate chest rise and TV’s (8-10/kg)

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Slide30

Correction of hypoxia and hypercarbia

To increase PaO2To decrease PaCO2Increase FiO2Increase RateIncrease PEEPIncrease Tidal Volume orPressure controlIncrease I-Time

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Slide31

Match the Gas

Which patient does this gas belong to?pH 7.09 PCO2 98 PO2 218 HCO3 30 A) 22 y/o with Muscular Dystrophy. Severe and worsening muscle weaknessB) 9 y/o with new onset Diabetic KetoacidosisC) A 30 y/o patient presenting with a panic attackD) A 25y/o in a skiing accident presenting in respiratory distress

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Slide32

Match the Gas

pH 7.09 PCO2 98 Po2 218 HCO3 30 A) 22 y/o with Muscular Dystrophy. Severe and worsening muscle weaknessChronic Respiratory FailureUncompensated Respiratory Acidosis

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Slide33

Match the Gas

Which patient does this gas belong to?pH 7.55 PCO2 28 PO2 63 HCO3- 23A) 22 y/o with Muscular Dystrophy. Severe and worsening muscle weaknessB) 9 y/o with new onset Diabetic KetoacidosisC) A 30 y/o patient presenting with a panic attackD) A 25y/o in a skiing accident presenting in respiratory distress

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Slide34

Match the Gas

Which patient does this gas belong to?pH 7.55 PCO2 28 PO2 63 HCO3- 23C) A 30 y/o patient presenting with a panic attackHyperventilationUncompensated Respiratory alkalosis

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Slide35

Match the Gas

Which patient does this gas belong to?pH 6.94 PCO2 26.6 PO2 55.7 HCO3 5.7 BD -27A) 22 y/o with Muscular Dystrophy. Severe and worsening muscle weaknessB) 9 y/o with new onset Diabetic KetoacidosisC) A 30 y/o patient presenting with a panic attackD) A 25y/o in a skiing accident presenting in respiratory distress

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Slide36

Match the Gas

pH 6.94 PCO2 26.6 PO2 55.7 HCO3 5.7 BD -27B) 9 y/o with new onset Diabetic KetoacidosisDKAUncompensated Metabolic Acidosis

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Slide37

Match the Gas

Which patient does this gas belong to?pH 7.27 PCO2 54.8 PO2 70 HCO3 26 BD -1A) 22 y/o with Muscular Dystrophy. Severe and worsening muscle weaknessB) 9 y/o with new onset Diabetic KetoacidosisC) A 30 y/o patient presenting with a panic attackD) A 25y/o in a skiing accident presenting in respiratory distress

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Slide38

Match the Gas

pH 7.27 PCO2 54.8 PO2 70 HCO3 26 BD -1D) A 25y/o in a skiing accident presenting in respiratory distressAcute Respiratory DistressUncompensated Respiratory Acidosis

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Questions?

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