Kuliah Asam Basa-Ined

7/28/2019 Kuliah Asam Basa-Ined

1/35

ACID-BASEIMBALANCE

Wan Nedra

Faculty of Medicine

YARSI University


2/35

Teaching aims

By the end of lecture session, the students

are expected to:

Understand the underlying concept of acid-base balance in human body

To maintain a balance between acids and

bases to achieve homeostasis

Arterial blood shows the make-up of bloodbefore it is distributed to the tissues


3/35


4/35

Regulators of Acid/Base

Buffers

Respiratory system

Renal system

Buffers:

- Primary regulators

- Act immediately

- Present in blood and tissues

- Take up extra H+ ions or release H+

- (bicarbonate, proteins, hemoglobin)


5/35

Respiratory system

Eliminates CO2 Respiratory center in medulla controls

breathing

Increased respiration leads to CO2eliminated from body and CO2 in blood

Decreased respiratory leads to CO2eliminated from body and CO2 in blood

Responds within minutes to hours tochanges in acid/base


6/35

Renal System

Selected hydrogen (H+) ion and

reabsorbs bicarbonate (HCO3) ions

Reabsorbtion and secretion ofelectrolytes (Na,Cl)

Responds within hours to days


7/35

Step to Acid Base

Analysis pH: Acidosis, alkalosis or normal

PaCO2: high or low? Causing or

compensating? HCO3: high or low or normal?

Causing or compensating? Short

or long term problem ?


8/35

Types of acid-base imbalance

acidosis

(ekses asam/defisit basa)

pH: 6,80-7,35

Metabolic: BE < 2.3

Respiratoric: PCO2 > 45

alkalosis

(ekses basa/defisit asam)

pH: 7,45- 7,80

Metabolic: BE > 2.3

Respiratoric: PCO2 > 45


9/35

Clinical manifestation pH PCO2 Bikarbonat

Metabolic AcidosisMetabolic Alkalosis

Respiratory Acidosis

Respiratory Alkalosis

Types of acid-base

imbalance


10/35

Respiratory Acidosis

Any condition that increases blood pCO2 (above45 mmHg, pH


11/35

Causes:

Hypoventilation:

Central nervous system

Peripheral nervous system Neuromuscular transmission

Muscle disorders

Chest wall abnormalities

Lung and airway disorders. Inhalation of CO2

Increased production of CO2


12/35

Carbonic acid excesscaused by blood levels of

CO2 above 45 mm Hg.

Hypercapnia high levels of CO2 in blood

Acute conditions:

Adult Respiratory Distress Syndrome

Pulmonary edema

Pneumothorax


13/35

Chronic conditions:

Depression of respiratory

center in brain that controlsbreathing rate drugs or head

trauma

Paralysis of respiratory orchest muscles

Emphysema


14/35

Compensation for Respiratory Acidosis

Kidneys eliminate hydrogen ion

and retain bicarbonate ion


15/35

Signs and Symptoms of RespiratoryAcidosis

Breathlessness

Restlessness

Lethargy and disorientation

Tremors, convulsions, coma

Respiratory rate rapid, then gradually depressed

Skin warm and flushed due to vasodilation

caused by excess CO2


16/35

Treatment of Respiratory Acidosis

Restore ventilation

IV lactate solution Treat underlying dysfunction or

disease


17/35

Respiratory Alkalosis

Respiratory alkalosis - any condition thatdecreases blood pCO2 (below 35 mmHg, pH>7.45).

This is associated with hyperventilation. Usuallythese are acute so there is no time for renalcompensation, but if prolonged, such as inacclimatization to high altitudes, there wouldprobably be renal compensation.


18/35

Carbonic acid deficit

pCO2 less than 35 mm Hg

(hypocapnea) Most common acid-base

imbalance

Primary cause is hyperventilation


19/35

Respiratory alkalosis (cont.)Causes:

Deliberate induced hyperventilation

during anaesthesia

Some causes of hypoxiaassociated with hyperventilation

Fever

Some types of C.N.S. damage

Hysterical hyperventilation


20/35

Conditions that stimulate respiratory center:

Oxygen deficiency at high altitudes

Pulmonary disease and Congestive heart failure caused by hypoxia

Acute anxiety

Fever, anemia

Early salicylate intoxication

Cirrhosis

Gram-negative sepsis


21/35

Compensation of Respiratory Alkalosis

Kidneys conserve hydrogen ion Excrete bicarbonate ion


22/35

Treatment of Respiratory Alkalosis

Treat underlying cause Breathe into a paper bag

IV Chloride containing solution

Cl- ions replace lost bicarbonate

ions


23/35

Metabolic Acidosis (non-respiratoryacidosis)

This (non-respiratory acidosis) is

due to increase in acids (i.e. H+

donating substances) other thanH2CO2 or decrease in base (i.e.

H+ acceptors) in the blood.

Compensation is by

hyperventilation. This lowers the

PaCO2 thus deducing the any pH

change


24/35

Metabolic acidosis (cont.)

Bicarbonate deficit - blood concentrations ofbicarb drop below 22mEq/L

Causes:

Increased alimentary or parenteral intake of acid

or alimentary loss of base (Loss of bicarbonate

through diarrhea)

Accumulation of acids (lactic acid or ketones)

Failure of excretion of acid (excrete H+) or loss ofbase by the renal system (or renal dysfunction)


25/35

Symptoms of MetabolicAcidosis

Headache, lethargy

Nausea, vomiting, diarrhea Coma

Death


26/35

Compensation for MetabolicAcidosis

Increased ventilation

Renal excretion of hydrogenions if possible

K+ exchanges with excess H+

in ECF

( H+ into cells, K+ out of cells)


27/35

Treatment of Metabolic Acidosis

IV lactate solution


28/35

Metabolic Alkalosis

Bicarbonate excess -concentration in blood is greaterthan 26 mEq/L

Causes:

Excess vomiting = loss of stomachacid

Excessive use of alkaline drugs Certain diuretics

Endocrine disorders

Heavy ingestion of antacids

Severe dehydration


29/35

Compensation for Metabolic Alkalosis

Alkalosis most commonly occurs

with renal dysfunction, so cant

count on kidneys

Respiratory compensation difficult

hypoventilation limited by

hypoxia


30/35

Symptoms of Metabolic Alkalosis

Respiration slow and shallow

Hyperactive reflexes ; tetany Often related to depletion of

electrolytes

Atrial tachycardia Dysrhythmias


31/35

Treatment of Metabolic Alkalosis

Electrolytes to replace those lost IV chloride containing solution

Treat underlying disorder


32/35

Example

A patient is in intensive care

because he suffered a severe

myocardial infarction 3 days ago.The lab reports the following

values from an arterial blood

sample:

pH 7.3 HCO3- = 20 mEq / L ( 22 - 26)

pCO2 = 32 mm Hg (35 - 45)


33/35

Diagnosis

Metabolic acidosis With compensation


34/35


35/35

Documents

Kuliah Asam Basa-Ined