pathophysiology of Acid base balance.pptx

pathophysiology of Acid base balance.pptx

1. Acid- base balance by Nagaba Ritah

2. Acid-Base Balance Measuring the pH on a scale from 1 to 14 Normally, blood has a pH of 7.35 to 7.45 The body has two main balancing systems: the respiratory system the renal system Respiratory imbalances (acidosis or alkalosis) are triggered by respiratory disorders Metabolic imbalances (acidosis or alkalosis) are triggered by metabolic disorders such as disorders of the gastrointestinal or renal system

3. Arterial blood gas analysis Provides important information on Respiratory function/gas exchange Metabolic status An integral tool in monitoring the acutely ill patient

4. Normal Values Variable Normal Range pH 7.35 - 7.45 pCO2 35-45 HCO3 22-26 PaO2 10.0-13.5

5. PaCO 2 Partial Pressure of Carbon Dioxide Amount of carbon dioxide gas dissolved in the blood Respiratory component of the compensatory system CO2 = Carbonic acid Normal values are 35-45 mmHg

6. HCO 3 - The bicarbonate ion metabolic component of the compensatory system Normal values are 22-26 ratio of bicarbonate to carbon dioxide is 20:1

7. PaO 2 Partial Pressure of Oxygen Amount of oxygen gas dissolved in blood plasma Measurement of pulling oxygen into the blood from the atmosphere Normal values are between 80-100 mmHg for an adult

8. Acid base disorders

9. Compensatory mechanisms. Acid base disturbance PH PCO2 PHCO3 Compensatory response Metabolic acidosis Immediate: respiratory compensation with hyperventilation and decrease in carbondioxide Respiratory acidosis or Delayed kidney compensation by retaining HCO3- Concentration generally >30. Metabolic alkalosis Immediate respiratory compensation by hypoventilation and retention of CO2 Respiratory alkalosis or Delayed compensation by the kidneys through HCO3- loss(concentration <18)

10. Renal Compensatory Mechanism When the pH is less than normal ( acidotic ), hydrogen ions are excreted When the pH is greater than normal, (alkalotic) hydrogen ions are conserved and base-forming ions are excreted Renal compensation takes hours to days Sodium, chloride, potassium, and bicarbonate may be stimulated by acid-base imbalances to move in and out of intracellular and extracellular compartments

11. Example: pH HCO 3 (Metabolic) pCO2 (Respiratory)  Acidosis  Acidosis  Acidosis  Alkalosis  Alkalosis  Alkalosis  Normal (7.40)  Normal (22-28)  Normal (35-45) pH HCO 3 (Metabolic) pCO2 (Respiratory)  Acidosis  Acidosis  Acidosis  Alkalosis  Alkalosis  Alkalosis  Normal (7.40)  Normal (22-28)  Normal (35-45) pH – 7.23 HCO 3 – 17 pCO 2 - 23 __________ Metabolic Acidosis

12. Brains at work!! pH-7.238, HCO 3 -32.5, pCO 2 -78 pH-7.492, HCO 3 -34.8, pCO 2 -46.4 pH-7.387, HCO 3 -10.1, pCO 2 -15.5 pH-7.30, HCO 3 -26, pCO 2 -58

13. Causes of Respiratory Acidosis Hypoventilation from: Sedation Trauma Upper airway obstruction Pulmonary edema Pneumonia COPD Muscular Weakness

14. Physiological Response to Respiratory Acidosis The physical signs of Respiratory Acidosis include: Headache Restlessness Confusion Weakness Tremor Coma Cyanosis or Pallor Tachycardia

15. Management of Respiratory Acidosis Improve the Ventilatory Status: Oxygen Therapy Mechanical Positive Pressure Ventilation Coughing or suctioning to clear airway Medication for bronchodilation

16. Causes of Respiratory Alkalosis Hyperventilation Anxiety Pain fever hypoxia high altitude

17. Physiological Response to Respiratory Alkalosis Signs of Respiratory alkalosis: Anxiety Hyperventilation Dizziness or lightheadedness Numbness or tingling of hands, feet and circum-oral Carpopedal spasms, Tetany or seizures

18. Care of the patient with Respiratory Alkalosis Correct the hyperventilation: Reduce anxiety Treat pain Coach the patient to take slow, sustained breaths Use an Non-rebreather oxygen mask Administer Normal Saline IV

19. Causes of Metabolic Acidosis Occurs from excreting too much HCO 3 - or retaining too much H + . Diabetes out of control as in DKA starvation Severe infection with fever Renal disease Overdose of medications Severe diarrhea Anaerobic metabolism Low sodium

20. Physiological Response to Metabolic Acidosis The compensatory responses : Increased rate and depth of respirations (Kussmaul Respiration) Stored Bicarbonate is released to neutralize the acids in the system Hyperkalemia muscle weakness Nausea Vomiting Diarrhea EKG morphology changes Lethargy, Stupor or Coma Warm flushed skin Hypotension

21. Management of Metabolic Acidosis Use NaHCO 3 - : sparingly and only when pH is less than 7.1 (potential complications) precipitous hypokalemia shift of the oxy-hemoglobin saturation curve to the left and decreased tissue unloading of oxygen induction of paradoxical CNS acidosis sodium or fluid overload increased serum osmolality

22. Management continued Insulin/Glucose IV drip will drive the potassium back into the cells DKA is primarily treated with large volumes of fluids, these patient have incredibly depleted intravascular volumes, (average 5-6 liters for adults) Patients require monitoring of cardiac and respiratory status may require ventilatory support

23. Causes of Metabolic Alkalosis Any disorder that causes a loss of natural acids can cause Alkalosis Vomiting or NG suctioning Overuse of antacids like Bicarbonate of Soda, Tums, Milk of Magnesia. Diuretics cause chloride depletion & hydrogen ion secretion. Cushing ’ s Syndrome Hypoaldosteronism Hypokalemia

24. Physiological Response to Metabolic Alkalosis The respiratory compensatory decreases the respiratory rate and depth The renal system will to retain hydrogen and excrete the NaHCO 3 - Potassium will be forced into the cell out of extracellular space. Multiple Electrolyte imbalances

25. Physiological Response to Metabolic Alkalosis As a result of the Electrolyte imbalances we may see Muscle twitching, tremors or even tetany - calcium Confusion, lethargy or coma or seizure - calcium We may see a depressed ST and inverted T waves on the EKG -calcium Muscle weakness - potassium Nausea, vomiting or diarrhea can be either the cause or the result of the alkalosis

26. Management of Metabolic Alkalosis Monitor of all electrolyte levels Monitor the cardiac and respiratory status Stop gastric suctioning Manage nausea and vomiting Stop all administration of antacids! Treat electrolyte imbalances with supplements carefully.