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Acids and Bases
  • Acid: Substances that releases H+ when dissolved in water
  • Base: Substances that wil bind to H+ when disolved in water.
Purpose of Acid-Base Balance
  • Metabolic processes produce acids that must be neutralized and excreted.
  • The body must maintain a stead balance between acids and bases.
Measurement of Balance
  • Measurement of H+ concentration
  • H+ ion conecntration <0.0001 mEq/L
  • Negative logarithim, inverse relationship (0-14, 7 neutral)
  • Blood is slightly alkaline at pH 7.35-7.45
  • <7.35 is acidosis
  • >7.45 is alkalosis
  • Death can occur outside 6.8/7.8
Regulators of Acid-Base
  • Buffers
  • Respiratory system
  • Renal system
Buffers
  • Protein buffer system
  • Phosphate buffer system
  • Hemoglobin/Oxyhemoglobin buffer system
  • Carbonic acid/Bicarb buffer system
Respiratory System
  • Eliminates CO2
  • Respiratory center in the medulla controls breathing
  • Responds within minutes/hours to change acid/base
  • Increased respirationslead to increased CO2 elimination and decreased CO2 in the blood
Renal system
  • Eliminates H+ and reabsorbs HCO3
  • Reabsorbs and secretes electrolytes (NA+, Cl-)
  • Responds within hours to days
  • Though slower, it is the ultimate correction
  • Can eliminate acids or bases
Alterations in Acid-Base Balance
  • Imbalances occur when compensatory mechanisms fail
  • Respiratory imbalances affect carbonic acid concentration
  • Metabolic imbalances affect bicarb
Classification of Imbalances
  • Respiratory Alkalosis: carbonic acid deficit
  • Respiratory Acidosis: carbonic acid excess
  • Metabolic Alkalosis: Bicarb excess
  • Metabolic Acidosis: Bicarb deficit
ABG collection
  • If a radial artery puncture, Allen's test
  • specimen should be place on ice
  • A K+ and ionized calcium level may be requested.
Blood Gas Values
  • ABG values provide information about:
  • Acid base status
  • Underlying cause of imbalance
  • Overall O2 status
Normal ABG ranges
  • pH: 7.35-7.45
  • PaCO2: 34-45
  • HCO3-: 22-26
  • PaCO2: 80-100
  • SaO2: >95%
Interpretation of ABGs
  • Evaluate pH for alkalosis/acidosis
  • Analyze PaCO2
  • Analyze HCO3
  • Determine if CO2 or HCO3 matches the alteration
  • decide if the body is trying to compensate
Acid-Base Mnemonic (ROME)
  • Respiratory Opposite Metabolic Equal
  • Respiratory alkalosis ↑pH ↓PaCO2
  • Respiratory acidosis ↓pH ↑PaCO2
  • Metabolic alkalosis ↑pH ↑HCO3
  • Metabolic acidosis ↓pH ↓HCO3
Respiratory acidosis
  • Excess carbonic acid caused by:
  • Hypoventilation (respiratory depression, inadequate chest expansion, airway obstruction, alveolar capillary exchange impairment)
  • respiratory failure
  • Compensation: kidneys conserve HCO3 and secrete H+ into the urine
Respiratory Acidosis Assessment
  • Drowsy, disoriented, HA, coma
  • hypotension, dysrhythmias, hyperkalemia, warm flushed skin
  • seizures
  • hypoventilation with hypoxia
Respiratory acidosis nursing Dx
  • Ineffective breathing pattern
  • Impaired gas exchange
  • Impaired sensory perception
  • Anxiety r/t breathlessness
  • risk for decreased cardiac output
  • risk for injury
Respiratory Acidosis interventions
  • Assess and monitor respiratory status (min q2h)
  • Provid pulmonary hygeine (suctioning)
  • high fowlers position
  • cautions use of oxygen as indicated
  • Monitor ABGs, EKGs, lytes
  • Teach risk and s/s to report
Respiratory Acidosis Medical interventions
  • Bronchodilators
  • Abx
  • Mucolytics
  • Steroids
  • Binders to reverse drug cause of respiratory depression
Respiratory Alkalosis
  • Carbonic acid deficit caused by:
  • Hyperventilation (hysteria/anxiety, pain, fever)
  • Hypoxemia (stimulates brainstem)
  • Compensation: rarely occurs d/t agressive treatmentof hypoxemia
Respiratory Alkalosis assessment
  • lightheaded, lethargic, confused
  • Tachycardia, dysrhythmias, hypokalemia, palpitations
  • Tetany, hypocalcemia, numbness, tingling of extremities, hyperreflexia, seizures
  • N/V
Respiratory Alkalosis nursing Dx
  • Ineffective breathing pattern
  • impaired thought process
  • Impaired sensory perception
  • risk for injury r/t tetany
  • risk for injury r/t weakness/seizures
Respiratory alkalosis interventions
  • assess and monitor respiratory status
  • provide calm enviroment
  • have pt slow breathing
  • have pt rebreathe CO2
  • teach relaxation techniques
  • Monitor ABGs, ECG, lytes
  • protect from injury
  • provide support and reassurance
Respiratory alkalosis medical interventions
  • sedatives
  • antianxiety medications
Metabolic Acidosis
  • Base bicarb deficit caused by:
  • ketoacidosis
  • lactic acid accumulation (Shock)
  • severe diarrhea
  • kidney disease
  • malnutrition
  • excessive ASA
Metabolic acidosis comensatroy mechanisms
  • Increased CO2 excretion by lungs (kussmal respirations)
  • kidneys excrete acid
Metabolic acidosis assessment
  • Drowsy, disoriented, HA, coma
  • hypotension, dysrhythmias, hyperkalemia, cold clammy skin
  • diarrhea
  • deep rapid respirations
metabolic acidosis nursing dx
  • Risk for decreased cardiac output
  • impaired sensory perception
  • risk for deficient fluid volume
  • risk for injury r/t confusion
Metabolic acidosis interventions
  • Monitor I/O
  • Monitor v/s and respiratory status
  • access loc
  • protect from injury
  • Monitor ABGs, ECG, lytes
  • teach to report prolonged diarrhea
  • teach DM pts s/s of DKA
Metablic acidosis medical interventions
  • treat the cause
Metabolic alkalosis
  • Base bicarb excess caused by:
  • prolonged vomiting or gastric suctioning
  • prolonged diuretic therapy
  • massive blood transfusion
  • hyperalosteronism
  • Gain of HCO3 from antacid abuse
Metabolic Alkalosis compensatory mechanisms
  • Decreased respiratory rate to increase plasma CO2
  • renal excretion of HCO3
Metabolic alkalosis assessment
  • drowsy, dizzy, confused
  • tachycardia, dysrhythmias, hypokalemia
  • hypoventilation
Metabolic alkalosis nursing dx
  • deficient fluid volume
  • risk for decreased cardiac output
  • deficient knowledge r/t medications
  • risk for impaired gas exchange
  • risk for injury
Metabolic alkalosis interventions
  • Assess and monitor respiratory status
  • monitor LOC
  • monitor I/O
  • protect from injury
  • Monitor ABGs, ECG, lytes
  • CAutions use of oxygen as indicatied
  • teach proper use of antacids
  • teach s/s of hypokalemia
Metabolic Alkalosis medical interventions
  • treat underlying problem
  • Cl- administration to enhance renal absorption of Na+ and excretion of HCO3
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