Tài liệu Acid-Base Balance doc

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 D

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”

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

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