Acid-Base Balance Disorders (Chapter 12) PDF

Critical Care Nursing Theory Chapter 12 Acid Base Balance Disorders Dr. Rana Al Awamleh 2024 Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 1 Dr. Rana Al Awamleh/ Assi...

Critical Care Nursing Theory Chapter 12 Acid Base Balance Disorders Dr. Rana Al Awamleh 2024 Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 1 Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 2  Definition Acid-base balance refers to the regulation of the concentration of hydrogen ions (H⁺) in the body to maintain a stable blood pH within the normal range of 7.35 to 7.45. This balance is critical for proper cellular function and is achieved through three primary mechanisms: 1.Buffer Systems: Immediate response systems (e.g., bicarbonate buffer) that neutralize excess acids or bases. 2.Respiratory System: Adjusts the levels of carbon dioxide (CO₂), which influences acidity. 3.Renal System: Regulates the excretion of hydrogen ions (H⁺) and the reabsorption or generation of bicarbonate (HCO₃⁻). Maintaining this balance ensures the proper functioning of enzymes, electrolytes, and other biological processes vital for health. Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 3 Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 4  Key Concepts ❑ pH: A measure of the hydrogen ion concentration. pH < 7.35: Acidosis (too much acid or too little base). pH > 7.45: Alkalosis (too much base or too little acid). ❑ Buffers: The bicarbonate buffer system is the primary buffer system in the blood: CO2+H2O H2CO3 H⁺+HCO3 Proteins, hemoglobin, and phosphate buffers also play roles in stabilizing pH. ❑ Respiratory Control: Lungs regulate the level of carbon dioxide (CO₂), a major acid in the body: Increased respiration decreases CO₂ → reduces acidity (raises pH). Decreased respiration retains CO₂ → increases acidity (lowers pH). ❑ Renal Control: Kidneys regulate bicarbonate (HCO₃⁻) and hydrogen ions: Secrete H⁺ into the urine and reabsorb or generate HCO₃⁻ to raise pH. Excrete HCO₃⁻ to lower pH. Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 5 Importance of maintaining pH for cellular processes 1. Enzyme Function Enzymes are highly sensitive to pH changes. Optimal enzymatic activity occurs within a specific pH range. Deviations can alter enzymes or alter their activity, disrupting critical metabolic processes like energy production and DNA replication. 2. Protein Stability Proteins, including structural and functional proteins, rely on proper pH to maintain their shape and function. Abnormal pH can lead to protein alteration, impairing their ability to perform tasks like transport and signaling. 3. Cell Membrane Integrity Extreme pH changes can disrupt the lipid bilayer, affecting membrane permeability and transport mechanisms. Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 6 Importance of maintaining pH for cellular processes 4. Electrolyte Balance pH affects the distribution and function of electrolytes like sodium (Na⁺), potassium (K⁺), and calcium (Ca²⁺), which are vital for nerve signaling, muscle contraction, and fluid balance. 5. Oxygen Delivery Hemoglobin's ability to bind and release oxygen is pH-dependent. An acidic pH (acidosis) reduces hemoglobin's affinity for oxygen, impairing oxygen delivery to tissues. 6. Metabolic Pathways Cellular respiration, glycolysis, and other metabolic processes are pH-sensitive. Deviations in pH can lead to inefficient energy production or harmful byproducts. 7. Nerve and Muscle Function Proper pH ensures the generation and propagation of action potentials in nerves and muscles. Abnormal pH can cause symptoms like seizures, arrhythmias, or muscle weakness. 7  Acid-Base Imbalance Disorders of acid-base balance occur when the body's mechanisms for regulating blood pH fail, leading to acidosis (pH < 7.35) or alkalosis (pH > 7.45). These disorders are categorized as either respiratory (caused by changes in CO₂ levels) or metabolic (caused by changes in bicarbonate or non-volatile acids). Types: ❖ Acidosis ❖Alkalosis Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 8  Acidosis 1. Respiratory Acidosis: ✓ Definition: Caused by hypoventilation, leading to CO₂ retention and increased carbonic acid (H₂CO₃) levels in the blood. ✓ Pathophysiology: CO₂ combines with water to form carbonic acid:CO2+H2O H2CO3 H⁺ +HCO3 Excess CO₂ increases H⁺ concentration, lowering pH. ✓ Causes: Acute: Airway obstruction, drug overdose (e.g., opioids), neuromuscular disorders (e.g., Guillain-Barré syndrome). Chronic: Chronic obstructive pulmonary disease (COPD), obesity hypoventilation syndrome. ✓ Compensation: Renal: Kidneys increase bicarbonate (HCO₃⁻) reabsorption and excrete H⁺, but this takes days. Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 9  Acidosis 2. Metabolic Acidosis ✓ Definition: Caused by either an excess of non-volatile acids or a loss of bicarbonate, resulting in decreased blood pH. ✓ Pathophysiology: Excess acid or decreased bicarbonate lowers pH. ✓ Causes: Renal failure, diabetic ketoacidosis, salicylates (aspirin overdose), diarrhea (bicarbonate loss). ✓ Compensation: Respiratory: Hyperventilation to expel CO₂ (Kussmaul breathing). Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 10  Comparison of Acid Disorders Feature Respiratory Acidosis Metabolic Acidosis Primary Issue Elevated CO₂ (hypercapnia) Decreased bicarbonate or excess acid Cause Hypoventilation Acid accumulation or bicarbonate loss pH Decreased (7.45). ✓ Pathophysiology: Excessive bicarbonate or loss of H⁺ shifts the bicarbonate buffer equilibrium, increasing alkalinity. ✓ Causes: Loss of Hydrogen Ions: Vomiting, nasogastric suction, diuretic use Excess Bicarbonate: Overuse of antacids, excess bicarbonate infusion (e.g., during resuscitation). Potassium or Chloride Imbalance: Hypokalemia or chloride depletion can impair acid excretion and worsen alkalosis. ✓ Compensation: Respiratory: Hypoventilation increases CO₂ to lower pH. However, compensation is limited because hypoxia can occur. Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 15  Comparison of Base Disorders Feature Respiratory Alkalosis Metabolic Alkalosis Primary Issue Decreased CO₂ (hypocapnia) Increased bicarbonate or H⁺ loss Cause Hyperventilation Vomiting, diuretics, antacid use pH Increased (>7.45) Increased (>7.45) Compensation Renal excretion of HCO₃⁻ Respiratory hypoventilation Examples Anxiety, high altitude, sepsis Vomiting, hyperaldosteronism Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 16  Treatment 1. Respiratory Alkalosis: Address underlying cause (e.g., anxiety, pain, hypoxemia). Rebreathing techniques (e.g., paper bag for hyperventilation-induced alkalosis). Adjust ventilator settings if caused by mechanical ventilation. 2. Metabolic Alkalosis: Rehydrate with saline (NaCl) for chloride-responsive alkalosis. Correct potassium and electrolyte imbalances. Treat underlying conditions (e.g., reduce diuretics, address aldosterone excess). In severe cases, consider acidifying agents like dilute hydrochloric acid. Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 17 Dr. Rana Al Awamleh/ Assistant Professor, Critical Care Nursing 18 General Nursing Interventions for All Acid-Base Disorders 1. Monitor Vital Signs: Observe for changes in respiratory rate, heart rate, and blood pressure. Assess oxygen saturation and mental status. 2. Perform Frequent Assessments: Monitor arterial blood gas (ABG) Watch for signs of compensation or worsening condition. 3. Ensure Proper Oxygenation: Provide supplemental oxygen if hypoxia is present. Adjust oxygen delivery devices based on patient needs and ABG results. 4. Fluid and Electrolyte Management: Administer IV fluids for dehydration or electrolyte imbalances. Monitor and correct potassium, chloride, calcium, and magnesium levels as needed. 19  Nursing Interventions for Respiratory Acidosis Goal: Improve ventilation and reduce CO₂ retention. 1. Promote Airway Clearance: Encourage coughing and deep breathing exercises. Use suctioning if necessary to clear secretions. 2. Positioning: Place the patient in a semi-Fowler's or Fowler's position to promote lung expansion. 3. Administer Medications: Bronchodilators (e.g., albuterol) for airway obstruction. Reversal agents for sedation or overdose (e.g., naloxone for opioids). 4. Support Ventilation: Administer non-invasive ventilation (e.g., BiPAP or CPAP) for acute cases. Collaborate with the healthcare team for mechanical ventilation if required. 5. Educate Patients: Teach breathing exercises for chronic conditions (e.g., COPD). 20  Nursing Interventions for Metabolic Acidosis Goal: Correct acidosis and address the underlying cause. 1. Administer IV Fluids: Provide isotonic fluids (e.g., normal saline) for dehydration. 2. Monitor for Compensatory Hyperventilation: Observe for Kussmaul breathing and ensure the patient is maintaining adequate oxygenation. 3. Administer Medications: Insulin for diabetic ketoacidosis (DKA). Sodium bicarbonate cautiously in severe acidosis (e.g., pH