Acid base disorders

BY : MUHANNAD ALI ASIRI432800225

Acid base balance

Acid-base balance refers to the mechanisms in the body uses to keep its fluids close to normal pH (that is, neither basic nor acidic) so that the body can function normally.

Arterial blood pH is normally : between 7.35 and 7.45

What is acid base balance

Why is acid-base balance important?

Because any disturbance in ph range effect on multi system and process in body as : Enzyme systems, oxygenation, muscle, nerve and metabolic functions of the body work best within a specific pH range.

Definition of acid-base disorders

An acid base disorder is a change in the normal value of extracellular pH that may result when renal or respiratory function is abnormal or when an acid or base load overwhelms excretion capacity .

Effects of acidosis: 1-depresses CNS2-decrease plumonary blood flow3-arrhythmias4-hyperkalemia

Effect of alkalosis :1- decrease cerbral blood flow2-seaizures3-arrhythmias

How to recognize abnormal acid- base? normal range

Abnormal ph (7.35-7.45)

Abnormal Hco 3 (22-24 mEq / L)

Abnormal pCO2 ( 35-40 mm Hg)

Abnormal anion gap (10-14 mEq / L )

REMEMBER

HCO3 level indication of METABOLIC problem

pCO2 level indication of RESPIRTORY problem

Henderson-hasselbach equation

[H+] = 24 ×

PCO2HCO3

-

Relationship between [H+] & CO2 & HCO3-

CO2 [H+]

CO2 [H+] (Positive

relationship)

HCO3- [H+]

HCO3- [H+] (Inverse

relationship)

Relationship between [H+] & pHpH [H+] pH [H+]

7.807.75

1618

7.307.25

5056

7.707.65

2022

7.207.15

6371

7.607.55

2528

7.107.00

7989

7.507.45

3235

6.956.90

100112

7.407.35

4045

6.856.80

141159

Relationship between [H+] & CO2 & HCO3- & ph

CO2 [H+] pH (respiratory acidosis)

CO2 [H+] pH (respiratory alkalosis)

HCO3 - [H+] pH

(metabolic alkalosis) HCO3

- [H+] pH (metabolic acidosis)

Some Causes of acid base disturbance (generally)Dm (m a)Shock ( septic,hypovolemic,cardognic) (m a)Renal failure (m a)Vomiting (m al)Diuretics (m al)Asthma (r al)Hyperventilation syndrome (r al)Copd (r a)Myasthenia gravis (r a)

Response to acid – base disturbance:H ＋

loadECF lung ICF Renal

Bone

Buffers

Mainly

Hco3

co2

Respiratory

controlCe

llular Hpo4

(weak)

H+ excret

ion

bicarbonat

e reabsorptio

n

Releas

e bon

e salt

H ＋

－K＋

exchange

Ca2 ＋＋H2PO4

In chroni

c metab

olic acidosi

s

H2CO3 CO2

Acid excretion

Hyperventilation

hyopventilation

Immediately minute

s

hours days Very slow

Compensatory MechanismsCompensation is the body’s way of restoring

a normal blood pH

Compensation DOES NOT treat the root of the problem – the reason for the acid-base imbalance is STILL THERE!!!

Simple vs Mixed acid base distrbance

Simple When compensation is appropriate

MixedWhen compensation is inappropriate

Remember: If abnormal ph (7.35-7.45) Acidosis or AlkalosisIf abnormal Hco3 Metabolic causeIf abnormal pCO2 Respiratory cause

TYPESMETOBLIC ACDOSISMETOBLIC ALKLOSISRESPIRTORY ACDOSISRESPIRTORY ALKLOSIS