Fluid, Electrolyte _ Acid-Base Abnormalities-2.pptx

FLUID, ELECTROLYTE & ACID-BASE ABNORMALITIES small animals dog & Cat.

CLASSIFICATION OF ACID-BASE DISTURBANCES
USUAL CAUSES OF ACID-BASE IMBALANCES
Respiratory Acidosis
Respiratory Alkalosis
Metabolic Acidosis
Diabetic acidosis (Diabetic Ketoacidosis)
Hyperchloremic acidosis (Loss of too much Sod. Bicarb; as in severe diarrhea)
Lactic acidosis;
Mixed Acid- Base Disorders�
DIAGNOSING THE PROBLEM
On the basis of alterations in pCO2 and HCO-3 , we can classify acid-base disturbances as
Respiratory acidosis (pCO2 > 40 mmHg)
Respiratory alkalosis (pCO2 24 mEq/L)
Note: Both the systems compensate for each other’s abnormalities in addition to other buffer systems.

TREATMENT CONSIDERATIONS
VARIOUS CLINICAL DISORDERS
Vomiting: Dehydration, K def;
metabolic alkalosis: Ringers Sol (KCl as an additive)
2. Diarrhea : Dehydration, K def (if chronic);
metabolic acidosis: Lactated Ringers Sol (KCl)
3. Diabetes mellitus: Dehydration, K def;
metabolic acidosis: Lactated Ringers Sol (KCl)
4. Adrenocortical insufficiency: Dehydration (vascular collapse), hyponatremia, hyperkalemia,
metabolic acidosis: Lactated Ringers Sol or N.S.


Urethral Obstruction: hyperkalemia,
metabolic acidosis: Lactated Ringers Sol
6. Acute renal insufficiency: hyperkalemia,
metabolic acidosis: Lactated Ringers Sol
7. Chronic renal insufficiency: Dehydration, hyponatremia,
slight metabolic acidosis: Lactated Ringers Sol (NaCl & NaHCO3 in food)
8. Prolonged anorexia: Dehydration, K def;slight metabolic acidosis: Lactated Ringers Soln.

1. FLUID, ELECTROLYTE & ACID-BASE ABNORMALITIES (ACID-BASE DISTURBANCES) Dr.Aman Ullah Zubair [DVM][RVMP]

2. ACID-BASE DISTURBANCES Henderson- Hasselbalch Equation (a condensed form) CO 2 +H 2 O H 2 CO 3 HCO - 3 + H + H + pH Acidosis H + pH Alkalosis

3. ACID-BASE DISTURBANCES Normal pH = 7.4 (7.35-7.45) Extreme Limits ( 7.0-7.8) Body fluid pH is maintained within narrow limits by three mechanisms Buffer: A compound that can accept or donate protons (H + ) to maintain pH within a narrow range Bicarbonates & Ammonia (ECF) Proteins, inorganic and Organic Phosphates (AMP, ADP, ATP, 2’3-diphosphoglycerate) and hemoglobin (ICF) (combine with & neutralize H + ) +

4. ACID-BASE DISTURBANCES 2. Ionic Shifts between ECF and ICF. ( K + & Cl - ) (k + with H + & Cl - with HCO - 3 ) 3 . Organ mediated compensatory responses: A . Renal (can excrete or retain acids or bases) B . Respiratory mechanisms (can excrete or retain CO 2 ).

5. pH Defence Mech of Body (Buffering Syatem ) Mechanism Example Peak of activity Chemical HCO 3 Instantaneous (Extracellular) Buffer system Ionic Shift H + with K + 2-4 hours (ICF/ECF) Cl - with HCO - 3

6. pH Defence Mech of Body (Buffering Syatem ) Mechanism Example Peak of activity Resp regulation CO 2 retention or excretion Minutes Renal Retn or excrtn Hours to days Regulation of acids or bases Sod . ions help to excrete H + and retain HCO - 3 ions

7. Renal Retention of HCO - 3 Tubular Fluid Renal tubular Cell Interstitial Fluid K Na Na Na Na + -H + exchange mechanism (HCO 3 ) + H H + HCO 3 Reabsorbed HCO 3 ( Fltrd ) H 2 CO 3 H 2 CO 3 Note: Reabsorption of HCO 3 but no net excretion of H + Diffuse H 2 O + CO 2 CO 2 + H 2 O

8. Renal Retention of HCO3 Tubular Fluid Renal tubular Cell Interstitial Fluid Na Na K H + - ATPase (HPO -2 4 ) + H H + HCO 3 New HCO 3 ( Fltrd ) Reabsorbed H 2 CO 3 H 2 PO - 4 Note: Net excretion of H + (Excreted) CO 2 + H 2 O

9. Renal Retention of HCO3 Tubular Fluid Renal tubular Cell Interstitial Fluid Na Na K H + -ATPase (NH 3 ) + H H + HCO 3 New HCO 3 (C.G) Reabsorbed NH 3 NH 4 Glutamine H 2 CO 3 C.G (Concentration Gradient) Note: Net excretion of H + (Excreted) CO 2 + H 2 O

10. CLASSIFICATION OF ACID-BASE DISTURBANCES 1. Respiratory origin due to variations (retention or loss) of CO 2 . (Acidosis or Alkalosis) 2. Non-respiratory origin (Metabolic) ; usually due to variations (retention or loss) of H + or HCO 3 – . (Acidosis or Alkalosis)

11. CLASSIFICATION OF ACID-BASE DISTURBANCES Evaluation of the abnormality is done through determination of a. pH b. pCO 2 c. HCO - 3 d. pO 2 of arterial blood (preferably) Acidosis & Alkalosis are the processes that cause net accumulation of acid or alkali in the body; whereas acedemia or alkalemia refer to pH of the ECF.

12. USUAL CAUSES OF ACID-BASE IMBALANCES Respiratory Acidosis: Retention of CO 2 Depression of resp. center (CNS injury, anesthesia ), inadequate mechanical ventilation, airway obstruction, primary lung disease, diaphragmatic hernia, pleural space abnormalities ( pyothorax , hemoyhorax , pneumothorax) 2. Respiratory Alkalosis: Excessive CO 2 loss Hyperventilation, stimulation of central respiratory center (fear, pain, anxiety, excitement) mechanical ventilator (excessive positive pressure ventilation)

13. USUAL CAUSES OF ACID-BASE IMBALANCES 3. Metabolic Acidosis: Loss of HCO - 3 , or retention or excessive production of H + Diabetic acidosis (Diabetic Ketoacidosis) Hyperchloremic acidosis (Loss of too much Sod. Bicarb ; as in severe diarrhea) Lactic acidosis; due to a. Prolonged exercise b. Lack of O2 c. Certain medicines d. Alcohol e. Kidney diseases f. Poisoning; too much aspirin, ethylene glycol, methanol, Salicylic acid

14. USUAL CAUSES OF ACID-BASE IMBALANCES 4. Metabolic Alkalosis: A. Loss of H + {Vomiting (loss of Na, K, Cl & H )} Gastric aspiration in the hospitals B. Gain of HCO - 3 ( excessive HCO - 3 administration)

15. Mixed Acid- Base Disorders The presence of only one of the derangements is called a simple acid–base disorder In a  mixed  disorder more than one is occurring at the same time If the actual response equals the calculated (predicted) response, then one acid-base disorder is present If the actual response differs from the calculated response, then more than one acid-base disorder is present.

16. Mixed Acid- Base Disorders T here can be two different conditions affecting the pH in the same direction The phrase "mixed acidosis", for example, refers to  metabolic acidosis  in conjunction with  respiratory acidosis ; as may be seen in diabetic ketoacidosis with Chronic Obstructive Pulmonary Disease (COPD) Any combination is possible, except concurrent respiratory acidosis and respiratory alkalosis, since a patient cannot breath too fast and too slow at the same time.

17. DIAGNOSING THE PROBLEM-1 Normal Values of pH, pCO 2 & HCO - 3 pH =7.4 pCO 2 = 40 mmHg pO 2 = 85 -95 mmHg HCO - 3 = 24 mEq / L pH < 7.4 ------------------- Acidosis pH > 7.4 ------------------- Alkalosis Most acid-base analysis are done at 37 C

18. DIAGNOSING THE PROBLEM-2 On the basis of alterations in pCO 2 and HCO - 3 , we can classify acid-base disturbances as Respiratory acidosis (pCO 2 > 40 mmHg) Respiratory alkalosis (pCO 2 < 40 mmHg) Metabolic acidosis (HCO - 3 < 24 mEq /L Metabolic alkalosis (HCO - 3 > 24 mEq /L) Note: Both the systems compensate for each other’s abnormalities in addition to other buffer systems.

19. DIAGNOSING THE PROBLEM-3 Check pH of the arterial blood Figure out the primary disturbance Check whether uncompensated or compensated by the buffering systems of the body. Remember, there is never overcompensation under normal conditions!

20. DIAGNOSING THE PROBLEM-4 pH = 7.25 pCO 2 = 50mmHg HCO - 3 = 24 mEq / L pO 2 = 70mmHg Uncompensated Respiratory Acidosis

21. DIAGNOSING THE PROBLEM-5 pH = 7.32 pCO 2 = 46mmHg HCO - 3 = 30 mEq / L pO 2 = 75mmHg Compensated Respiratory Acidosis

22. DIAGNOSING THE PROBLEM-6 pH = 7.60 pCO 2 = 28mmHg HCO - 3 = 24mEq / L pO 2 = 85mmHg Uncompensated Respiratory Alkalosis

23. DIAGNOSING THE PROBLEM-7 pH = 7.52 pCO 2 = 32mmHg HCO - 3 = 16mEq / L pO 2 = 90mmHg Compensated Respiratory Alkalosis

24. DIAGNOSING THE PROBLEM-8 pH = 7.20 pCO 2 = 40mmHg HCO - 3 = 14mEq / L pO 2 = 85mmHg Uncompensated Metabolic Acidosis

25. DIAGNOSING THE PROBLEM-9 pH = 7.32 pCO 2 = 28mmHg HCO - 3 = 18mEq / L pO 2 = 85mmHg Compensated Metabolic Acidosis

26. DIAGNOSING THE PROBLEM-10 pH = 7.59 pCO 2 = 40mmHg HCO - 3 = 32mEq / L pO 2 = 85mmHg Uncompensated Metabolic Alkalosis

27. DIAGNOSING THE PROBLEM-11 pH = 7.50 pCO 2 = 54mmHg HCO - 3 = 29mEq / L pO 2 = 80mmHg Compensated Metabolic Alkalosis

28. TREATMENT CONSIDERATIONS-1 pCO 2 + - 5 No need to interfere HCO - 3 + - 4 No need to interfere Respiratory Acidosis: Trt should be directed at the cause of CO 2 retention. Ventilatory assistance may be needed. Respiratory Alkalosis: Eliminate the cause for excessive loss of CO 2

29. TREATMENT CONSIDERATIONS-2 Metabolic Acidosis: Lactated Ringer’s (1mEq of lactate = 1mEq of bicarbonate). In severe cases, NaHCO 3 as an additive to lactated Ringer’s. Formula= Normal HCO - 3 – Measured HCO - 3 x BW (kg) x 0.3 / Equivalent weight of HCO - 3 Eg : 24 – 16 x 20 x 0.3 / 12 = 4 gm of HCO - 3

30. TREATMENT CONSIDERATIONS-3 Metabolic Alkalosis: Relatively uncommon in dogs and cats. Therapy depends upon the cause If dt over administration of alkali, discontinue it If dt vomiting (loss of H, Cl - & depletion of K + ) Administer sol. containing high Cl - conc & enough K + . Ringer’s solution (initial therapy) & KCl (as additive) Always under correct the condition Consider : Paradoxical acidosis of CSF.

31. VARIOUS CLINICAL DISORDERS-1 Vomiting: Dehydration, K def ; metabolic alkalosis: Ringers Sol ( KCl as an additive) 2. Diarrhea : Dehydration, K def (if chronic); metabolic acidosis: Lactated Ringers Sol ( KCl ) 3. Diabetes mellitus: Dehydration, K def ; metabolic acidosis: Lactated Ringers Sol ( KCl ) 4. Adrenocortical insufficiency: Dehydration (vascular collapse), hyponatremia , hyperkalemia, metabolic acidosis: Lactated Ringers Sol or N.S.

32. VARIOUS CLINICAL DISORDERS-2 5. Urethral Obstruction: hyperkalemia, metabolic acidosis: Lactated Ringers Sol 6. Acute renal insufficiency: hyperkalemia, metabolic acidosis: Lactated Ringers Sol 7. Chronic renal insufficiency: Dehydration, hyponatremia , slight metabolic acidosis: Lactated Ringers Sol ( NaCl & NaHCO 3 in food) 8. Prolonged anorexia: Dehydration, K def ; slight metabolic acidosis: Lactated Ringers Sol