Acid Base balance, Outline PDF

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Acid-Base Balance and Arterial Blood Gases Purpose  Maintain a steady balance between acids and bases to achieve homeostasis  Health problems lead to imbalance o Diabetes mellitus o Vomiting and diarrhea o Respiratory conditions pH  Measure of H+ ion concentration  Blood is slightly alkaline pH 7.35 to 7.45 o Below 7.35 is acidosis o Above 7.45 is alkalosis Regulators of Acid/Base  Metabolic processes produce acids that must be neutralized and excreted  Regulatory mechanisms o Buffers o Respiratory system o Renal system  Buffers: act chemically to neutralize acids or change strong acids to weak acids o Primary regulators o React immediately o Cannot maintain pH without adequate respiratory and renal function  Respiratory system: eliminates CO2 o Respiratory center in medulla o controls breathing o Responds within minutes/hours to changes in acid/base o Increased respirations lead to increased CO2 elimination and decreased CO2 in blood  Renal system: eliminate H+ and reabsorb HCO3o Reabsorption and secretion of electrolytes (e.g., Na+, Cl-) o Responds within hours to days  Kidneys usually secrete acidic urine (pH 6)  Kidneys can increase or decrease pH as a compensatory mechanism Alterations in Acid-Base Balance  Imbalances occur when compensatory mechanisms fail  Classification of imbalances o Respiratory: affect carbonic acid concentration o Metabolic: affect bicarbonate  Respiratory acidosis  Respiratory alkalosis  Metabolic acidosis  Metabolic alkalosis  Mixed acid-base disorders Respiratory Acidosis  Carbonic acid excess caused by o Hypoventilation o Respiratory failure  Compensation

o Kidneys conserve HCO3- and secrete H+ into urine Interventions: Respiratory Acidosis  Focus is on improving ventilation and oxygenation, maintaining patent airway  Drug therapy o Bronchodilators o Anti-inflammatories o Mucolytics  Oxygen therapy  Pulmonary hygiene  Ventilation support  Prevention of complications Respiratory Alkalosis  Carbonic acid deficit caused by o Hyperventilation o Hypoxemia from acute pulmonary disorders  Compensation o Rarely occurs due to aggressive treatment of causes of hypoxemia  Hyperventilation—anxiety, fear, improper vent settings, stimulation of central respiratory center due to fever, DNS lesion, salicylates Metabolic Acidosis  Base bicarbonate deficit caused by o Ketoacidosis o Lactic acid accumulation (shock) o Severe diarrhea o Kidney disease  Compensatory mechanisms o Increased CO2 excretion by lungs  Kussmaul respiration (deep and rapid) o Kidneys excrete acid Interventions: Metabolic Acidosis  Hydration  Drug therapy o Insulin to treat DKA o Antidiarrheals o Bicarbonate (only with low serum level) Metabolic Alkalosis  Base bicarbonate excess caused by o Prolonged vomiting o Gain of HCO3 Compensatory mechanisms o Decreased respiratory rate to increase plasma CO2 o Renal excretion of HCO3 Base excess—excessive intake bicarbonates, carbonates, acetates, citrates  Acid deficit—prolonged vomiting, excess cortisol, hyperaldosteronism, thiazide diuretics, prolonged NG suction Combined Metabolic & Respiratory Acidosis  Uncorrected respiratory acidosis leads to poor oxygenation and lactic acidosis  More severe than metabolic or respiratory acidosis alone

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Combined problem of DKA and COPD lead to this

Acidosis: Patient-Centered Collaborative Care  History  CNS changes  Neuromuscular changes o ↓ muscle tone, deep tendon reflexes  Cardiovascular changes o Early: ↑ heart rate, cardiac output changes o Worsening: hyperkalemia; ↓ heart rate; T wave peaked and QRS widened; weak peripheral pulses; hypotension  Respiratory changes o Kussmaul respiration  Skin changes (metabolic and respiratory acidosis) o Warm, dry, and pink (vasodilation)  Psychosocial assessment Alkalosis: Patient-Centered Collaborative Care  Assessment (same for metabolic and respiratory alkalosis)  Hypocalcemia  Hypokalemia  CNS changes—positive Chvostek’s and Trousseau’s signs  Neuromuscular changes—tetany  Cardiovascular changes  Respiratory changes Interventions: Alkalosis  Prevent further losses of hydrogen, potassium, calcium, chloride ions  Restore fluid balance  Monitor changes, provide safety  Modify or stop gastric suctioning, IV solutions with base, drugs that promote hydrogen ion excretion Diagnosis  Arterial blood gas o Specimen? o Who performs the procedure? o How is it done? o What are important nursing implications? Blood Gas Values  Arterial blood gas (ABG) values provide information about o Acid-base status o Underlying cause of imbalance o Body’s ability to regulate pH o Overall oxygen status Interpretation of ABGs  Diagnosis in six steps o Evaluate pH o Analyze PaCO2 o Analyze HCO3o Determine if CO2 or HCO3- matches the alteration o Decide if the body is attempting to compensate  Respiratory o ↑ pH, ↓ PaCO2 o ↓ pH, ↑ PaCO2

Metabolic o ↑ pH, ↑ HCO3 o ↓ pH, ↓ HCO3 Interpretation of ABGs pH 7.36 PaCO2 67 mm Hg PaO2 47 mm Hg HCO3 37 mEq/L What is this? 

pH 7.18 PaCO2 38 mm Hg PaO2 70 mm Hg HCO3- 15 mEq/L What is this? pH 7.60 PaCO2 30 mm Hg PaO2 60 mm Hg HCO3- 22 mEq/L What is this? pH 7.58 PaCO2 35 mm Hg PaO2 75 mm Hg HCO3- 50 mEq/L What is this? pH 7.28 PaCO2 28 mm Hg PaO2 70 mm Hg HCO3- 18 mEq/L What is this ? Acid-Base Mnemonic—ROME  Respiratory  Opposite o pH PaCO2 Alkalosis o pH PaCO2 Acidosis  Metabolic  Equal o pH PaCO2 Alkalosis o pH PaCO2 Acidosis Case Study 1: Jeri Jeri’s been on a 3-day party binge Friends are unable to awaken her Assessment reveals level of consciousness difficult to arouse Respiratory rate 8 Shallow breathing pattern Diminished breath sounds 1. What ABGs do you expect? 2. What is your treatment?

Case Study 2: Mayna Presented to the ER after a sexual assault Physical examination reveals hysterical emotional distress Respiratory rate 38 Lungs clear O2 sat 96% Case Study 2: Mayna 1. What ABGs do you expect? 2. What is your treatment? Case Study 3: Glen History of fever, aches, and chills Generally feeling ill Cough productive of yellow, thick sputum for the past 4 days Examination reveals temp 38.4° C Respiratory rate 20 Lungs with crackles in left lower lobes 1. Identify and write at least three nursing diagnoses. 2. What are your goals? Nursing interventions? Evaluation? Case Study 4: Alan 17 years old History of  Feeling bad  Fatigue  Constant thirst  Frequent urination Blood sugar is 484 mg/dl Respirations are 28 and deep Breath has a fruity odor His lungs are clear 1. What ABGs do you expect? 2. What is your treatment?...