Presentation on Hydrogen Ion Homeostatis (Acid base balance, a clinical application).

1. HYDROGEN ION HOMEOSTASIS
(Acid-Base Balance, A Clinical Application)
Dr. C.S. REX SARGUNAM, MD (Ped), DCH
PEDIATRIC CONSULTANT, St Isabel’s Hospital
PEDIATRIC CONSULTANT, VHS
FORMER DIRECTOR & SUPERINTENDENT
INSTITUTE OF CHILD HEALTH & HOSPITAL FOR CHILDREN
PRESIDENT, TAMILNADU, HEALTH DEVELOPMENT
ASSOCIATION, CHENNAI
Email: csrexsargunam@yahoo.co.in
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2. FREE H+ ions
Free H+ ions are present in the human
system in very minute quantities
0.00004 mEq/l
Or
40nM/l ± 5nM
Na+ Conc 140mEq/l
This is around 3 million times than normal H
+ ions concentration.
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3. Normal Sources of H+ ions
1. Dietary Protein Metabolism
2. Incomplete Metabolism of
Carbohydrates & Fats
3. Stools Losses of HCO-
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A child produces 2-3 mEq/Kg/24hr.
An adult produces 1-2 mEq/Kg/24hr.
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4. pH
pH is a measure of Free H+ ion Conc.
Normal pH 7.4 (7.35 to 7.45)
(1 nMol change in Free H+ ions conc. changes pH by 0.01)
pH is Inversely Related to Free H+ ions Conc
Higher the H+ ions conc. Lower is the pH
i.e. Acidosis
Lower the H+ ions conc. Higher is the pH
i.e. Alkalosis.
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5. BUFFERS
Buffer is a combination of weak acid and weak
base (H2CO3 + NaHCO3 )
Acids Donate an H+ ions eg:
H2CO3 (weak)
CH3COOH (strong)
Bases Accept an H+ ions eg:
NaHCO3 (weak)
NaOH (strong)
Best Buffers are weak Acids + Bases
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6. Buffers in Human system-Buffer System
Bicarbonates 60% (open system)
Because CO2 as an acid is Excreted
Non-bicarbonate Buffer
Proteins
Albumin Histidine Bind H+
Haemoglobin Release
Phosphate Intracellular & Urinary
Bones NaHCO3 Release or Base
CaCO3 Bind
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7. An Unique Buffer
H2CO3 + NaHCO3
CO2 acts as an Acid
CA
CO2 + H2O H2 CO3 → H + HCO 3
H + Hb → H Hb
HCO-
3 + Na → NaHCO3
Lungs (CO2 Excreted)
Plasma
Kidneys
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8. Regulation Mechanism
Lungs Regulate CO2 Conc.
Kidneys Regulate HCO-
3 Conc.
Buffers Correction Immediately
RS Compensatory Correction within 24hrs
Kidney compensatory correction takes 3 to 4 days
(Tubular) Lumen Renal Cell Per tubular Capillary
PT Na HCO3
→HCO-
3 PT
DT H ←
Reclamation
Regeneration
Average 70mEq. Of HCO-
3 is regenerated per 24 hr.
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9. Diagnosis
ABG pH 7.4
PCO2 40mm of Hg
PO2 95 - 100mm of Hg
Serum Electrolytes Na + 135 – 150 mEq/L
K + 3.5 - 5.5 mEq/L
HCO3- 24 mEq/L
Cl- 110 mEq/L
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10. DIAGNOSIS
pH
↓ ↑
Acidosis Alkalosis
HCO-
3
Metabolic↓ RS ↑ ↑ Metabolic RS↓
Egs: AGE (Diarrhoea) Respiratory Vomiting Hysterical
Breathing
Diabetic keto-acidosis Failure NG Aspiration Breathing
Renal Failure Hepatic Failure
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11. Mixed Disorders
Respiratory Failure Corpulmonale with Excess
Diuretics)
eg: Respiratory Acidosis eg: Respiratory Acidosis
Metabolic Acidosis Metabolic Alkalosis
Fulminant Hepatic Failure
eg: Respiratory Alkalosis
Metabolic Acidosis
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12. CLINICAL PRESENTATION
Acidosis
Rapid Breathing in MA
pH < 7.20
Depresses Myocardiam -Decreases the cardiac output
Risk of Arrythmias
Hypotensian – arteriolar dilatation
Pulmonary odema
Pulmonary vasoconstriction (NB)
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13. MANAGEMENT
TREAT THE CAUSE
Fluid for correction in Metabolic Acidosis Isolyte P
With Dehydration RL, ECF Replacement Fluid
Acidosis
1) NaHCO3 2mEq/Kg 8th hourly IV Infusion
8.4% Soln NaHCO3 - 1ml = 1m EqNa + 1m EqHCO3
2) In an Emergency Situation
NaHCO3 BOLUS 1mEq/Kg
3) Dialysis
4) Respiratory Acidosis
Moderate amounts of NaHCO3
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NS 844 ml
NaHCO3 (1 mEq/ml) 24 ml
5% GDW To make up the rest 1 L

14. Clinical Presentation continued
Alkalosis
Tetany, Paresthesia and Convulsions
Severe Alkalosis
Decreases Cardiac Output
Arrhythmias
Respiratory Alkalosis
Light headedness & Syncope
Metabolic Alkalosis
Decrease the Respiratory drive.
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15. Alkalosis (Management)
1) Volume deficit correction
2) Correction Fluid NS NO RL
3) K+ deficit Correction
Arginine HCl being tried
Respiratory Alkalosis may be treated
by Rebreathing Exhaled CO2.
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16. For any communication, contact:
csrexsargunam@yahoo.co.in
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