Unit V.Acid base Imbalance bsn 3rd semester patho.pptx

acid base balance pathophysiology 3rd semester respiratory and metabolic acidosis and respiratory and metabolic akkalosis

1. Unit V: Homeostasis Imbalance Part B: Acid Base Imbalance BSc. Nursing 3rd Semester By:Muqaddas Munir

2. Outline: B.Acid Base Imbalance Review the physiological mechanism responsible to regulate acid base balance in the body i.e. 1.Buffers(phosphate, hemoglobin, carbonate) 2.Renal mechanism 3.Respiratory mechanism 4.Discuss the classification of acid base imbalance in terms of; Respiratory acidosis Respiratory alkalosis Metabolic alkalosis

3. Outline continued..... 5.Discuss how to interpret the arterial blood gases (ABGs) to identify four types of acid base imbalance. 6.Discuss the causes, pathophysiology and clinical manifestation of Respiratory acidosis & alkalosis Metabolic acidosis & alkalosis

4. What is Acid-Base Balance? Definition: Acid-base balance refers to the homeostatic regulation of the pH of the body's fluids. Normal Blood pH: 7.35–7.45 Importance: Essential for enzyme function, oxygen delivery, cellular metabolism

5. Acid-Base Imbalance: Definition: A condition where blood pH falls outside the normal range Types: Acidosis: pH < 7.35 Alkalosis: pH > 7.45 Causes: Respiratory or metabolic disorders

6. ✅ Physiological Mechanisms Behind Acid-Base Balance: The human body maintains a tightly controlled blood pH between 7.35 and 7.45. Deviations outside this range can disrupt cellular functions and lead to serious health issues. To maintain acid-base balance, the body uses three main physiological mechanisms: 1. Buffer Systems (Immediate response) 2. Respiratory Mechanism (Short-term regulation) 3. Renal Mechanism (Long-term regulation)

7. 1. Buffer Systems: Buffer systems are the first line of defense in maintaining acid-base balance. They act immediately to resist changes in pH by neutralizing excess hydrogen ions (H⁺) or hydroxide ions (OH⁻). They do not remove acids or bases from the body; instead, they temporarily "soak them up" until the respiratory and renal systems can eliminate them.

8. 🧪 Main Buffer Systems in the Human Body 1. Bicarbonate Buffer System (HCO₃⁻ / H₂CO₃): ✅ Components: Bicarbonate ion (HCO₃⁻) – a weak base Carbonic acid (H₂CO₃) – a weak acid 🔁 Reaction : H + +HCO 3 −​ ↔H 2​ CO 3​ ↔CO 2​ +H 2​ O If there is too much acid (H⁺) → Bicarbonate binds with H⁺ to form carbonic acid → broken down into CO₂ + H₂O → CO₂ is exhaled by lungs. If there is too much base (OH⁻) → Carbonic acid donates H⁺ to neutralize OH⁻ → forms H₂O.

9. CONTINUED.... 🫁 Controlled by: Lungs (remove CO₂) Kidneys (reabsorb or excrete HCO₃⁻) 📍 Location: Extracellular fluid (blood plasma)

10. 2. Phosphate Buffer System (H₂PO₄⁻ / HPO₄²⁻): ✅ Components: Dihydrogen phosphate (H₂PO₄⁻) – weak acid Monohydrogen phosphate (HPO₄²⁻) – weak base 🔁 Reaction: H 2 PO 4 −​ ↔H + +HPO 4 2−​ Acts similarly to bicarbonate system: If pH drops (acidosis) → HPO₄²⁻ binds H⁺ → forms H₂PO₄⁻ If pH rises (alkalosis) → H₂PO₄⁻ releases H⁺ → forms HPO₄²⁻

11. CONTINUED.... 📍 Location: Intracellular fluid Renal tubules 🩺 Important in: Kidney function, especially urine pH regulation

12. 3. Protein Buffer System (including Hemoglobin): ✅ Components: Proteins contain amino acid groups that can act as acids or bases Hemoglobin (Hb) is a major buffer in red blood cells ⚙ ️ How it Works: Proteins have: COOH group → releases H⁺ when pH rises NH₂ group → binds H⁺ when pH drops

13. CONTINUED.... Hemoglobin binds with: H⁺ ions to prevent acidity CO₂ forming carbaminohemoglobin (helps remove CO₂) 📍 Location: Intracellular fluids Blood (RBCs)

14. Respiratory Mechanism as a Buffer System: Introduction to Respiratory Mechanism: Second line of defense (after buffer systems) Acts within minutes to adjust blood pH Regulates the level of carbon dioxide (CO₂) in blood CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻

15. Why CO 2 Matters: Carbon dioxide (CO₂) is produced by cells during metabolism. In the blood, CO₂ combines with water to form carbonic acid (H₂CO₃): CO 2​ +H 2​ O⇌H 2​ CO 3​ ⇌H + +HCO - 3 More CO₂ → More H⁺ → Lower pH (Acidosis) Less CO₂ → Less H⁺ → Higher pH (Alkalosis)

16. 🧬 Step-by-Step Process: Inside Cells and Lungs: 🔬 1. CO₂ Production in Cells Cells produce CO₂ during energy production (cellular respiration). CO₂ diffuses from the cells → into nearby capillaries (bloodstream). 🚛 2. Transport of CO₂ in the Blood CO₂ travels in 3 ways: 70%: As bicarbonate ion (HCO₃⁻) (after reacting with water in RBCs) 20-25%: Bound to hemoglobin (as carbaminohemoglobin) 5-10%: Dissolved directly in plasma 👉 Inside red blood cells, the enzyme carbonic anhydrase catalyzes this reaction:CO 2​ +H 2​ O → ​H 2​ CO 3​ →H + +HCO 3 -

17. Continued.... The H⁺ is buffered by hemoglobin (Hb). The HCO₃⁻ is transported in plasma to the lungs. 🫁 3. CO 2 removal in the Lungs: At the lungs: Oxygen (O₂) enters the blood and binds to hemoglobin. This causes CO₂ to be released from hemoglobin. The reaction reverses: H + +HCO 3 −​ →H 2​ CO 3​ →CO 2​ +H 2​ O CO₂ diffuses into alveoli and is exhaled through breathing. ✅ This is how the body “excretes” acid — by removing CO₂, which is an acid-forming compound.

18. Respiratory Compensation (Fast-Acting) When pH drops (acidosis) → brain signals faster breathing → more CO₂ exhaled → pH increases When pH rises (alkalosis) → slower breathing → more CO₂ retained → pH decreases

19. 🧬 3. Renal Regulation (Third Line of Defense): The kidneys regulate acid-base balance by: Excreting H⁺ ions Reabsorbing or excreting bicarbonate (HCO₃⁻) In Acidosis: Kidneys excrete more H⁺ Reabsorb more HCO₃⁻ In Alkalosis: Kidneys retain H⁺ Excrete HCO₃⁻ Speed: Takes hours to days but provides long-term correction

20. Acid-Base Imbalance: Normal Blood pH: 7.35 – 7.45 Acidosis: pH < 7.35 (more acid) Alkalosis: pH > 7.45 (more base) 📌 Classification: Respiratory Acidosis Respiratory Alkalosis Metabolic Acidosis Metabolic Alkalosis

21. Respiratory Acidosis: Definition: A condition where CO 2 retention due to hypoventilation leads to increased carbonic acid, causing blood pH to drop below 7.35. Causes: Chronic lung diseases: COPD, asthma Respiratory depression (from sedatives, narcotics) Neuromuscular disorders: Guillain-Barré, ALS Airway obstruction: choking, foreign body Chest wall abnormalities: trauma, obesity

22. Pathophysiology: Hypoventilation → CO₂ is retained CO₂ + H₂O ⇌ H₂CO₃ ⇌ H⁺ + HCO₃⁻ ↑ CO₂ leads to ↑ H⁺ → ↓ pH (acidosis) Kidneys compensate by reabsorbing HCO₃⁻ and excreting H⁺ (takes time)

23. Clinical Manifestations: Headache, confusion, drowsiness Slow, shallow breathing Cyanosis (if severe) Muscle weakness Arrhythmias (due to hyperkalemia) ABG: ↓ pH, ↑ PaCO₂, normal or ↑ HCO₃⁻ (if compensated)

24. Treatment: Improve ventilation: Bronchodilators, oxygen therapy Mechanical ventilation (if needed) Treat underlying cause Monitor ABGs and electrolytes Encourage deep breathing exercises

25. Respiratory Alkalosis: Definition: When excessive CO₂ is lost due to hyperventilation, raising blood pH above 7.45. Causes: Anxiety, panic attacks Fever or pain Early stages of sepsis High altitude Mechanical overventilation

26. Pathophysiology: Hyperventilation → excessive CO₂ loss ↓ CO₂ → ↓ H₂CO₃ → ↓ H⁺ → ↑ pH Blood becomes alkaline Kidneys compensate by excreting HCO₃⁻ and retaining H⁺

27. Clinical Manifestations: Dizziness, lightheadedness Tingling in fingers and around mouth (paresthesia) Muscle cramps, twitching Palpitations Seizures (if severe) ABG: ↑ pH, ↓ PaCO₂, ↓ HCO₃⁻ (if compensated)

28. Treatment: Treat underlying cause (anxiety, fever, pain) Encourage slow breathing Paper bag method (re-breathing CO₂) Adjust ventilator settings if needed Monitor ABGs

29. Metabolic Acidosis: Definition: A condition where HCO₃⁻ is lost or acid builds up, leading to blood pH < 7.35. Causes: Diabetic ketoacidosis (DKA) Renal failure (can't excrete H⁺) Severe diarrhea (loss of bicarbonate) Lactic acidosis (shock, sepsis) Ingestion of toxins: methanol, aspirin overdose

30. Pathophysiology: ↑ H⁺ production or ↓ HCO₃⁻ ↓ HCO₃⁻ buffer → pH drops Lungs compensate by increasing ventilation → CO₂ is lost (Kussmaul breathing) Kidneys (if functioning) increase acid excretion and bicarbonate reabsorption

31. Clinical Manifestations: Rapid, deep breathing (Kussmaul respiration) Fatigue, confusion Nausea, vomiting Hypotension, arrhythmias Warm, flushed skin ABG: ↓ pH, ↓ HCO₃⁻, ↓ PaCO₂ (if compensated)

32. Treatment: Treat underlying cause: Insulin for DKA Fluids for dehydration Dialysis for renal failure Administer sodium bicarbonate (if severe) Monitor ABGs and electrolytes

33. Metabolic Alkalosis: Definition: A condition caused by excess base (HCO₃⁻) or loss of acid, leading to high pH (>7.45). Causes: Prolonged vomiting (loss of gastric acid) NG tube suctioning Overuse of antacids or bicarbonate Diuretics (loss of H⁺ and K⁺) Cushing’s syndrome

34. 🔬 Pathophysiology: Loss of H⁺ or gain of HCO₃⁻ → ↑ pH Lungs compensate by reducing ventilation → retain CO₂ Kidneys attempt to excrete excess HCO₃⁻

35. 🩺 Clinical Manifestations: Muscle cramps, weakness Tetany, seizures Confusion or irritability Shallow breathing Hypokalemia signs: arrhythmias, fatigue ABG: ↑ pH, ↑ HCO₃⁻, ↑ PaCO₂ (if compensated)

36. Treatment: Replace lost fluids (IV NS with KCl) Treat vomiting or suction losses Stop diuretics if possible Monitor ABGs and electrolytes Correct hypokalemia

37. ✅ Key ABG Components to Know: ABG Parameter Normal Range Meaning pH 7.35 – 7.45 Acidity or alkalinity of blood PaCO₂ 35 – 45 mmHg Respiratory component (lungs) HCO₃⁻ 22 – 26 mEq/L Metabolic component (kidneys)

38. 🧪 Steps to Interpret ABGs: 🔍 Step 1: Check the pH pH < 7.35 → Acidosis pH > 7.45 → Alkalosis Step 2: Check the PaCO₂ (Respiratory) PaCO₂ > 45 mmHg → Respiratory Acidosis PaCO₂ < 35 mmHg → Respiratory Alkalosis 🔍 Step 3: Check the HCO₃⁻ (Metabolic) HCO₃⁻ < 22 mEq/L → Metabolic Acidosis HCO₃⁻ > 26 mEq/L → Metabolic Alkalosis

39. Continued.... 🔍 Step 4: Match the Component with the pH If PaCO₂ matches the pH direction → Respiratory cause If HCO₃⁻ matches the pH direction → Metabolic cause 🔍 Step 5: Check for Compensation Uncompensated: One value (CO₂ or HCO₃⁻) is abnormal, the other is normal Partially compensated: Both CO 2 and HCO₃⁻ are abnormal, but pH is still out of range Fully compensated: CO₂ and HCO₃⁻ are abnormal, but pH is normal

40. 📊 The Four Main Types of Acid-Base Imbalances : 1. Respiratory Acidosis Parameter Value pH ↓ (< 7.35) PaCO₂ ↑ (> 45 mmHg) HCO₃⁻ Normal or ↑ (if compensated)

41. 2. Respiratory Alkalosis Parameter Value pH ↑ (> 7.45) PaCO₂ ↓ (< 35 mmHg) HCO₃⁻ Normal or ↓ (if compensated)

42. 3. Metabolic Acidosis: Parameter Value pH ↓ (< 7.35) PaCO₂ Normal or ↓ (if compensated) HCO₃⁻ ↓ (< 22 mEq/L)

43. 4. Metabolic Alkalosis: Parameter Value pH ↑ (> 7.45) PaCO₂ Normal or ↑ (if compensated) HCO₃⁻ ↑ (> 26 mEq/L)

44. Example 1: pH = 7.30 PaCO₂ = 50 mmHg HCO₃⁻ = 24 mEq/L Interpretation: ? Example 2: pH = 7.50 PaCO₂ = 30 mmHg HCO₃⁻ = 22 mEq/L Interpretation: ?

45. Example 3: pH = 7.48 PaCO₂ = 47 mmHg HCO₃⁻ = 29 mEq/L Interpretation: ? Example 4: pH = 7.36 PaCO₂ = 30 mmHg HCO₃⁻ = 18 mEq/L Interpretation: ?

46. Case: A 45-year-old male with type 1 diabetes presents with vomiting, fruity-smelling breath, and deep, rapid breathing. Blood sugar: 480 mg/dL. ABG Results: pH: 7.22 PaCO₂: 28 mmHg HCO₃⁻: 14 mEq/L Interpretation: ?

47. Case: A 60-year-old woman with a history of frequent vomiting for 3 days due to gastritis complains of weakness and muscle cramps. She is on diuretics for hypertension. ABG Results: pH: 7.49 PaCO₂: 48 mmHg HCO₃⁻: 32 mEq/L Interpretation: ?

48. Case: A 25-year-old woman arrives at the ER after a panic attack. She is hyperventilating, dizzy, and complains of tingling in her hands and around her mouth. ABG Results: pH: 7.52 PaCO₂: 30 mmHg HCO₃⁻: 24 mEq/L Interpretation: ?

49. Case: A 68-year-old male with a history of COPD presents with worsening shortness of breath, drowsiness, and confusion. Respiratory rate is 10/min, shallow breathing. He is on home oxygen. ABG Results: pH: 7.28 PaCO₂: 58 mmHg HCO₃⁻: 25 mEq/L Interpretation: ?