Dialysis YouTube Lecture Handouts
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Dialysis/Artificial Kidney
Is a procedure in which principles of diffusion are applied for the treatment of renal failure?
Types
- Hemo dialysis
- Peritonial dialysis
Hemo Dialysis
Solution is prepared in which
- Waste products are absent
- Electrolytes are adjusted
- Nutrients are provided
Solution is separated from patient՚s blood by a dialyzing membrane.
Blood is normalised by the process of diffusion.
Peritoneal Dialysis
- In it diffusion takes place across the patient՚s own peritoneal membrane
- About 1 L of sol. is introduced in peritoneal cavity
- Kept for 20 to 60 min & replaced by fresh fluid
Peritoneal Dialysis
- Indications
- In acute renal failure, most of the time condition is reversible. Dialysis can support the patient for a few weeks during the period of crisis
- In patient of chronic renal failure it is life saving
- Permanent sol. is Renal Transplantation
Renal Transplantation
- Were among the first transplants to be done and are among the most successful transplants
- Both cadavar & live donors are used
- Detailed antigen typing of both is done
- Immuno suppression is required
- Occasionally a graft is rejected
PH Expression
- H + concentration is very low & their expression is very cumbersome
- It is customary to express them on a logarithm scale
Normal H + is 40 nEq/L (0.00000004 Eq. /L. & the Ph. Is)
PH of Body
- pH is – ve log. of concentration
- Normal concen. in body fluids
- Normal variation
- Concen. is maintained in a very narrow range
PH of Some Body Fluids
- Plasma pH
- Arterial … 7.4
- Venous … 7.35
- Extra cellular fluid … 7.35 to 7.45
- Intra cellular fluid … 6 to 7.4
- Urine … 6 (4.5 to 8)
- Gastric HCl … 0.8
PH
- pH compatible with life 6.8 to 8.0 & person can live for few hours.
- Daily H+ production or ingestion about 80 mEq
- These excess of ions must be removed
Acid Produced in Body
- Acids produced in body
- Volatile acids
- Nonvolatile acids
Volatile Acids
- a major end product of metabolism
- Removed by lungs as
- It accounts for about
Nonvolatile/Fixed Acids
- Sulphuric acid — end product of sulpher containing aminoacids eg. Cystenine, methionine metabolism
- Phosphoric acid — end product of phospholipid metabolism
- Hydrochloric acid — end product of lysine, arginine & histidine mata.
Fixed Acids
- Organic Acids
- Lactic acid … severe anemia
- Acetoacetic acid, hydroxy butyric acid … uncontrolled D. M.
- Uric acid … metabolism of nucleoproteins
Base Production
- Negligible amount
- Bicarbonate … metabolism of organic anions eg. Citrates
- Ammonia … from metabolism of amino acids is converted to urea, so not important
Buffering of H+ Ions
- Any substance that can reversibly bind H+ ions is buffer
- Reaction can go in both directions
Regul. Of pH
- Body Buffers — 3 Systems
- Chemical Buffers … come into action with in fraction of seconds. They keep ions tied up
- Respiratory System … acts with in minutes Renal System … acts over a period of hours to days. Most efficient
Chemical Buffers
- Forms I line of defence
- Three types
- Bicarbonate buffers
- Phosphate buffers
- Protein buffers
Bicarbonate Buffer
- Has two components
- Weak Acid
- A salt with strong Base
When a strong acid is added. Like
- A strong acid is converted to a weak acid
- If a strong base is added, NaOH
- Weak base is formed
- Thus change in pH is minimized
Quantitative Dynamics
- BICARBONATE BUFFER
- is ionized
- It՚s dissociation constant is (1)
- The amount of free is (2)
- cannot be measured but is proportionate to (3)
- The solubility coefficient for is 0.03 mmol/mm Hg at body temp.
- Therefore, equation 3 can be written as (4)
- concentration is expressed as pH units
- ions
- Similarly dissociation constant can be expressed as
- Thus (5)
- therefore (6)
- If we change the sign
- (7)
- (8)
Bicarbonate Buffer System Titration Curve
Handerson-Hasselbalch Eq
Phosphate Buffer
- Two components are
- important buffer in
- Renal tubules &
- Intracellular fluid (high concentration)
Protein Buffer
- Have
- Free carboxyl group
- Free amino gp.
- Important intracellular buffer
PK of Some Buffer Systems
- Bicarbonate System … 6.1
- Dibasic System … 6.8
- Proteins …
- Ammonia … 9.0
- Effective buffers are those with pKs close to the pH. of fluid in which they are operating
Principal Buffers in the Body Fluids
- 1 Whole blood
- Hemoglobin
- Proteins
- Bicarbonates
- 2 Intrestitial fluid … Bicarbonate
- 3 Intracellular fluid
- Proteins
- phosphates
Respiratory System
- II line defense
- Hyperventilation … Alkalosis
- Hypoventilation … Acidosis
- Effect is mediated by change in CO2 concen.
Renal System
- III line defense
- Acts by
- Reabsorption of bicarbonates
- Generation of new bicarbonates
- H+ excretion
Disorders of Acid-Base Balance
- Simple
- Metabolic Acidosis
- Metabolic Alkalosis
- Respiratory Acidosis
- Respiratory Alkalosis
Mixed Disorders
- Metabolic Acidosis & Resp. Acidosis
- “& Res. Alkalosis”
- Metabolic Alkalosis & Res. Alkalosis
- “& Res. Acidosis”
Anion Gap
- The concentration of anions & cations must be equal in plasma, so there is no real gap
- We measure only some anions & cations
- The anion gap is a diagnostics concept
Anion Gap
- Is the difference between unmeasured anions & unmeasured cations
- Normal range is