Abd2009

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  • Abd2009

    1. 1. Disturbance Of Acid-Base Regulation Dr. Matongjun Emergency Department of Tianjin General Hospital
    2. 2. ABG <ul><li>pH 7.35 – 7.45 </li></ul><ul><li>P CO2 35 – 45 mmHg </li></ul><ul><li>P O2 75 – 100 mmHg </li></ul><ul><li>HCO 3 - 22 – 26 mmol/L </li></ul>
    3. 3. Acid-base homeostasis <ul><li>Buffer system </li></ul><ul><ul><li>Carbonic acid / Bicarbonate </li></ul></ul><ul><li>Organ regulation </li></ul><ul><ul><li>Lungs </li></ul></ul><ul><ul><ul><li>Characteristic: Sensitive, quickly, but tired easily so can not continue long term </li></ul></ul></ul><ul><ul><li>Kidneys </li></ul></ul><ul><ul><ul><li>Characteristic: powerful but slower (hours to days) </li></ul></ul></ul>
    4. 5. Henderson-Hasselbalch equation pH=pKa+lg [HCO 3 - ] [H 2 CO 3 ]
    5. 7. Category <ul><li>SABD </li></ul><ul><ul><li>pH: acidosis, alkalosis </li></ul></ul><ul><ul><li>Etiology: respiratory, metabolic </li></ul></ul><ul><li>MABD </li></ul><ul><ul><li>Two or three SABD are taking place simultaneously </li></ul></ul>
    6. 8. Metabolic Acidosis
    7. 9. Definition <ul><li>HCO 3 - ↓ , H + ↑ </li></ul><ul><ul><li>pH   HCO 3 -  * compensation process P CO 2  * </li></ul></ul>
    8. 10. manifestation <ul><li>Kussmaul’s respiration </li></ul><ul><li>Nausea , vomiting and abdominal pain </li></ul><ul><li>Tachycardia, cardiac output decrease and hypotension </li></ul><ul><li>Headache, weakness, lethargy and confusion, the level of consciousness is depressed, the deep tendon reflex decrease. </li></ul><ul><li>Alter plasma potassium and Calcium concentration </li></ul>
    9. 11. Category <ul><li>Increased anion gap and normal anion gap </li></ul><ul><li>Anion Gap </li></ul><ul><ul><li>[Na + ] - ( [Cl - ] + [HCO 3 - ] ) </li></ul></ul><ul><ul><li>Normal range 8~16 mmol/L </li></ul></ul><ul><ul><li>unmeasured anions, consist of proteins (primarily albumin), sulfates, phosphates, and organic acids </li></ul></ul>
    10. 12. Anion Gap All anions and cations in Serum TOTAL 151 TOTAL 151 Sulfates 1 Phosphates 2 Magnesium 1.5 Organic acids 5 Potassium 4.5 Proteins 15 Calcium 5 Bicarbonate 24 Sodium 140 Chloride 104 CATIONS ANIONS
    11. 13. Category <ul><li>Increased AG </li></ul><ul><ul><li>HCO 3 - decreases and replaced by other anions </li></ul></ul><ul><li>Normal AG (hyperchloremic) </li></ul><ul><ul><li>HCO 3 - decreases and replaced by Cl - </li></ul></ul>
    12. 14. Elevated AG Metabolic Acidosis Lactic acidosis L Unmeasured osmoles , Ethylene glycol, Aldehydes , Paraldehydes U Alcoholic lactic acidosis A Methanol ingestion M Starvation ketosis S Salicylate intoxication S Uremia U Diabetic ketoacidosis K Etiology
    13. 15. <ul><li>increased serum chloride concentrations </li></ul><ul><li>generally due to gastrointestinal or renal bicarbonate wasting </li></ul><ul><li>Ingestion of chloride salts or chloride-containing anion exchange resins </li></ul>Normal AG Metabolic Acidosis
    14. 16. Treatment <ul><li>Remove the Cause </li></ul><ul><li>alkali therapy </li></ul><ul><ul><li>Benefit: decrease the risk of cardiovascular compromise </li></ul></ul><ul><ul><li>Risk: 5%NaHCO 3 is hyperosmotic, hypernatremia, hypercapnia, cerebrospinal fluid acidosis, and overshoot alkalosis </li></ul></ul><ul><ul><li>Indication: renal failure; arterial blood pH below 7.20 or HCO 3 - concentration below 10 mmol/L </li></ul></ul><ul><ul><li>Goal: Maintain the blood pH > 7.20 and plasma HCO 3 - concentration > 10 mmol/L </li></ul></ul>
    15. 17. Metabolic Alkalosis
    16. 18. definition <ul><li>plasma HCO 3 - concentration >27 mmol  L </li></ul><ul><li>arterial blood pH>7.40 </li></ul><ul><li>Compensation </li></ul><ul><ul><li>PaCO 2 ↑ </li></ul></ul>
    17. 19. Etiology <ul><li>loss of acid from GI tract or urine, loss fluid with a chloride HCO 3 - concentration ratio that is higher than plasma </li></ul><ul><ul><li>loss of gastric contents, Vomiting or nasogastric suctioning. </li></ul></ul><ul><ul><li>Diuretics (Cl lost ) </li></ul></ul><ul><ul><li>Hyperaldosteronism (H + and Cl - lost ) </li></ul></ul><ul><li>alkaline drugs ingestion </li></ul><ul><ul><li>Antacid overuse (HCO 3 - ) </li></ul></ul><ul><ul><li>Blood transfusions (citrate ) </li></ul></ul>
    18. 20. Diagnosis <ul><li>History </li></ul><ul><li>Symptoms </li></ul><ul><ul><li>Irritability and Possible tetany, tingling , facial twitching, muscle tremors </li></ul></ul><ul><ul><li>volume depletion : weakness, postural dizziness </li></ul></ul><ul><ul><li>hypokalemia : muscle weakness, paresthesias </li></ul></ul><ul><li>physical examination </li></ul><ul><ul><li>respiratory rate </li></ul></ul><ul><ul><li>BP(hypertension+Hypokalemia+metabolic alkalosis suggest primary mineralocorticoid-induced disease) </li></ul></ul>
    19. 21. Treatment <ul><li>stopping the intake of soda bicarbonate </li></ul><ul><li>Saline-responsive </li></ul><ul><ul><li>Correct volume deficits </li></ul></ul><ul><ul><li>potassium supplementation : 4.5-5.5 mmol/L </li></ul></ul><ul><ul><li>H 2 R antagonists : ranitidine, cimetidine, diminish H + secretion; pump inhibiter, Omeprarole </li></ul></ul><ul><li>Saline-unresponsive </li></ul><ul><ul><li>remove the mineralocorticoid source or block with spironolactone </li></ul></ul>
    20. 22. Respiratory Acidosis
    21. 23. Definition <ul><li>Lungs fail to eliminate CO 2 so PaCO 2 is elevated </li></ul><ul><li>Compensation </li></ul><ul><ul><li>HCO 3 - ↑ </li></ul></ul>
    22. 24. Etiology <ul><li>inhibition of the respiratory center: head trauma, Neurological disorders, anesthesia </li></ul><ul><li>disorders of respiratory muscle: Chest trauma </li></ul><ul><li>upper airway obstruction </li></ul><ul><li>disorders affecting gas exchange across pulmonary capillaries: COPD, pneumonia, acute or chronic respiratory failure , cardiac arrest </li></ul>
    23. 25. Signs and Symptoms <ul><li>respiratory distress, dyspnea </li></ul><ul><li>level of consciousness  </li></ul><ul><li>If severe, patients may complain of headaches or show signs of increased intracranial pressure </li></ul><ul><ul><li>due to the vasodilatory properties of C0 2 , increase cerebral blood flow </li></ul></ul>
    24. 26. Pathophysiology <ul><li>Acute Compensation </li></ul><ul><ul><li>l mmol/L increase in HCO 3 - for each 10mmHg in PCO 2 </li></ul></ul><ul><ul><li>The HCO 3 - rarely rises above 30mmol/L </li></ul></ul><ul><li>Chronic Compensation </li></ul><ul><ul><li>Over the next 2-3 d </li></ul></ul><ul><ul><li>the kidneys increase H + secretion leading to an elevation of serum HCO 3 - by 3~4mmol/L for each 10mmHg increase in PaCO 2 </li></ul></ul>
    25. 27. Treatment <ul><li>improving ventilation </li></ul><ul><li>HCO 3 - should not be given </li></ul><ul><li>Oxygen should also be used with care </li></ul><ul><li>Diet: Low carbohydrate, high fat </li></ul>
    26. 28. Respiratory Alkalosis
    27. 29. Definition <ul><li>decrease in blood PaCO 2 </li></ul><ul><li>compensatory decrease in HCO 3 - . </li></ul>
    28. 30. Causes of Respiratory Alkalosis <ul><li>Increased CNS drive for respiration </li></ul><ul><ul><li>Anxiety </li></ul></ul><ul><ul><li>CNS infection/infarction/trauma </li></ul></ul><ul><ul><li>Drugs - salicylates/nicotine/aminophylline </li></ul></ul><ul><ul><li>Fever/sepsis - especially Gram-negative sepsis </li></ul></ul><ul><ul><li>Pregnancy/progesterone </li></ul></ul><ul><ul><li>Anemia, Pulmonary edema/pneumonia , Pulmonary emboli </li></ul></ul><ul><ul><li>Carbon monoxide toxicity </li></ul></ul><ul><ul><li>Reduced inspired 0 2 tension - high altitude </li></ul></ul><ul><li>Increased mechanical ventilation </li></ul>
    29. 31. Signs and Symptoms <ul><li>hyperventilation: rapid, deep respirations </li></ul><ul><li>perioral and extremity paresthesias, muscle cramps, seizures </li></ul><ul><li>cardiac arrhythmias </li></ul><ul><li> K + ,  Ca + </li></ul>
    30. 32. Pathophysiology <ul><li>Acute Compensation </li></ul><ul><ul><li>extra-and intra-cellular buffering , l~2mmol/L fall in HCO 3 - for every 10mmHg decrease in PaCO 2 The HCO3- rarely goes below 18mmol/L. </li></ul></ul><ul><li>Chronic Compensation </li></ul><ul><ul><li>kidneys decrease the secretion of H + , serum HCO 3 - decreases 4~5mmol/L for every 10mmHg decrease in PaCO 2 . </li></ul></ul>
    31. 33. Treatment <ul><li>correcting the underlying disorder </li></ul><ul><ul><li>In ICU, hypoxemia and improper ventilatory settings are the most common cause </li></ul></ul><ul><ul><li>Rebreathing in a paper bag can help the patient with psychogenic hyperventilation </li></ul></ul><ul><li>Treatment of the alkalosis is usually not necessary </li></ul><ul><li>Antianxiety medications, diazepam </li></ul>
    32. 34. Diagnosis <ul><li>The proper evaluation of patients with suspected acid-base disorders requires consideration of </li></ul><ul><li>The clinical picture </li></ul><ul><li>Blood Gas Results </li></ul><ul><li>Serum electrolytes </li></ul>
    33. 35. Diagnosis <ul><li>metabolic or respiratory </li></ul><ul><ul><li>determined by the primary change, in HCO 3 - or PCO 2 </li></ul></ul><ul><li>acute or chronic </li></ul><ul><ul><li>An acute process is measured in minutes to hours </li></ul></ul><ul><ul><li>a chronic process is measured in days to weeks or longer </li></ul></ul><ul><li>simple or mixed </li></ul><ul><ul><li>The primary change of simple disorder is in only one parameter </li></ul></ul><ul><ul><li>The primary change of mixed disorder is in both </li></ul></ul>
    34. 36. ABG <ul><li>The simplest approach to the evaluation of blood gases is to consider pH. Pco 2 and HCO 3 - separately and then combine the information </li></ul>
    35. 37. ABG Interpretation <ul><li>Identify whether pH, pCO 2 , and HCO 3 are abnormal </li></ul><ul><li>pH 7.30 </li></ul><ul><li>pCO2 55 </li></ul><ul><li>HCO3 26 </li></ul><ul><li>Match like disorders </li></ul><ul><li>pH and pCO 2 are both </li></ul><ul><li>the two matching values tell what the problem is – Acidosis or Alkalosis </li></ul>
    36. 38. ABG Interpretation <ul><li>Determine if abnormality is due to the kidneys (metabolic ) or the lungs (respiratory) </li></ul><ul><li>pH 7.30 </li></ul><ul><li>pCO2 55 </li></ul><ul><li>HCO3 26 </li></ul><ul><li>Match the like abnormalities </li></ul><ul><li>Respiratory (lung problem) and Acidosis </li></ul><ul><li>= Respiratory Acidosis </li></ul><ul><li>Acid </li></ul><ul><li>Acid = LUNGS </li></ul><ul><li>Normal = Kidneys </li></ul>
    37. 39. MABD <ul><li>The compensation can be expected. If the compensation is outside the expected range, it is a MABD </li></ul><ul><li>Two methods to diagnose MABD </li></ul><ul><ul><li>Method I  A rigorous method which involves calculation of the expected compensations </li></ul></ul><ul><ul><li>Method II   Look on a nomogram </li></ul></ul><ul><ul><li>If Pco 2 and HCO 3 - change in opposite direction   consider a MABD </li></ul></ul>
    38. 40. Method I <ul><li>Metabolic </li></ul><ul><ul><li>Acidosis: Expected pCO 2 = 1.5 x [HCO 3 - ] + 8 ± 2 </li></ul></ul><ul><ul><li>Alkalosis: Expected pCO 2 =↑6 mmHg per 10 mEq/L  ↑ in HCO 3 - </li></ul></ul>
    39. 41. Method I <ul><li>Respiratory </li></ul><ul><ul><li>Acidosis </li></ul></ul><ul><ul><ul><li>Acute Expected  ↑ HCO 3 - = ↑ 1mEq/L for each 10 mm  ↑ PCO 2 </li></ul></ul></ul><ul><ul><ul><li>Chronic: Expected  ↑ HCO 3 - = ↑ 3.5mEq/L for each 10 mmHg  PCO 2 </li></ul></ul></ul><ul><ul><li>Alkalosis </li></ul></ul><ul><ul><ul><li>Acute Expected ↓ HCO 3 - = ↓ 2mEq/L for each 10 mm Hg  ↓ PCO 2 </li></ul></ul></ul><ul><ul><ul><li>Chronic Expected  ↓ HCO 3 - = ↓ 5 mEq/L for each 10 mmHg ↓ PCO 2 </li></ul></ul></ul>
    40. 42. Example 1 <ul><li>pH=7.08, pCO 2 =14, HCO 3 - =4, Na=140, Cl=104 </li></ul><ul><ul><li>The pH is low indicating the primary disorder is acidosis. </li></ul></ul><ul><ul><li>The anion gap is 140 - (104 + 4) = 32, thus elevated </li></ul></ul><ul><ul><li>The pCO 2 is low, the expected compensation </li></ul></ul><ul><ul><li>The predicted pCO 2 by the above equation is 1.5×4+8 = 14 , This is the observed pCO 2 </li></ul></ul><ul><ul><li>simple increased anion gap metabolic acidosis </li></ul></ul><ul><li>pH=7.08, pCO2=14, HCO3-=4, Na=140, Cl=124 ? </li></ul>
    41. 43. Example 2 <ul><li>pH 7.37, pCO 2 =18, HCO 3 - =10, Na=140, Cl=114 </li></ul><ul><li>the pH to be normal </li></ul><ul><li>The anion gap is 16, thus increased </li></ul><ul><li>Expected pCO 2 is 1.5×10+8 = 23 (21 at minimum), there must be an element of respiratory alkalosis </li></ul><ul><li>a combination of increased anion gap metabolic acidosis and a respiratory acidosis </li></ul>
    42. 44. Example 3 <ul><li>In a patient with severe COPD, and who is diuretics, the pH=7.42, pCO 2 = 65, HCO 3 - =41, Na 143, K 3.1, Cl 88 </li></ul><ul><li>Start with a metabolic alkalosis, why? </li></ul><ul><li>pCO 2 should be 50.2 mmHg </li></ul><ul><ul><li>6 mmHg CO 2 for each 10 mEq/L HCO 3 - , 41-24 = 17; 1.7×6 + 40 = 50.2 mmHg </li></ul></ul><ul><li>pCO 2 is measured at 65, there is a respiratory acidosis </li></ul>
    43. 46. Thank you

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