Tài liệu Acid-Base Balance doc

Acid-Base
Balance
Ahmed Abughaban
2021040088

Acid-Base abnormalities

Metabolic Acidosis

Metabolic Alkalosis

Respiratory Acidosis

Respiratory Alkalosis

Mechanisms of acid-base
balance
Respiratory system
Kidneys
Buffers
HCO3 reabsorption
Excretion of organic acids
Titrable acids (HPO4) Ammonium (NH4)
Ca, Hb, PP
bones


Metabolic Acidosis

Definition:


Primary decrease in serum HCO3

Decreased pH

Accumulation of acids

Anion Gap
Represents the unmeasured anions
in plasma.
AG=Na - (Cl + HCO3)
Normal AG= 10-12 mEq/L

Causes of ↑AG metabolic acidosis:
“Accumulation of acids”
1. lactic acidosis
2. Ketoacidosis - diabetic, alcoholic, starvation
3. Toxins - ethylene glycol, methanol, salicylates
4. RF - acute & chronic


Causes of normal AG metabolic acidosis:
1- Renal
•
RTA
•
Fanconi’s synd
2- GIT
•
Severe diarrhea

•
GIT fistula

3- Drugs (+ renal
insuff.)
•
K sparing diuretics
•
Heavy metals
•
ACEIs
•
NSAIDs
“Loss of alkali”

POG
unmeasured
NON-IONIZED
AG
unmeasured
IONIZED
Plasma Osmolal Gap
POG= measured - calculated plasma osm

Steps in Acid-Base Diagnosis

Obtain ABG & electrolytes

Check pH & compare HCO3 on ABG &
measured for accuracy


Calculate AG

Try to identify the cause according to the
AG

Estimate compensatory response
(PaCo2 ↓ 1.25 mmHg per mmol/L ↓ in HCO3)

ABG findings in metabolic acidosis

pH < 7.35

HCO3 < 24 mEq/L

paCO2 < 35 mmHg (compensated)

Treatment of metabolic acidosis

TREAT THE CAUSE
Hydrate the pt IV HCO3*
*HCO3 only when (1) pH < 7.1 (2)HCO3<10mEq/L
1/2 dose IV bolus, then cont. IV infusion over 12-24h
HCO3 deficit=0.6 x BW x (desired HCO3 - actual HCO3)

Thank You