Acid Base Balance[1]Edit

5/25/2018 Acid Base Balance[1]Edit

1/36

ACID-BASE

IMBALANCE

Wan Nedra

Faculty of Medicine

YARSI University


2/36

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


3/36


4/36

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)


5/36

Respiratory system

Eliminates CO2 Respiratory center in medulla controls

breathing

Incresed respiration leads to CO2eliminated from body and CO2in blood

Decresed respiratory leads to CO2eliminated from body and CO2in blood

Responds whithin minutes to hours tochanges in acid/base


6/36

Renal System

Selected hydrogen (H+) ion and

reabsorbs bicarbonate (HCO3) ions

Reabsorbtion and secretion ofelectrolytes (Na,Cl)

Respons within hours to days


7/36


8/36

Types of acid-base imbalance

Respiratory acidosis

Respiratory alkalosis

Metabolic acidosis

Metabolic alkalosis


9/36

Respiratory Acidosis

Any condition that increases blood pCO2 (above45 mmHg, pH


10/36

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


11/36

Carbonic acid excesscaused by blood levels of

CO2above 45 mm Hg.

Hypercapniahigh levels of CO2 in blood

Acute conditions:

Adult Respiratory Distress Syndrome

Pulmonary edema

Pneumothorax


12/36

Chronic conditions:

Depression of respiratory

center in brain that controlsbreathing ratedrugs or head

trauma

Paralysis of respiratory orchest muscles

Emphysema


13/36

Compensation for Respiratory Acidosis

Kidneys eliminate hydrogen ion

and retain bicarbonate ion


14/36

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


15/36

Treatment of Respiratory Acidosis

Restore ventilation

IV lactate solution Treat underlying dysfunction or

disease


16/36

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.


17/36

Carbonic acid deficit

pCO2less than 35 mm Hg

(hypocapnea) Most common acid-base

imbalance

Primary cause is hyperventilation


18/36

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


19/36

Conditions that stimulate respiratory center:

Oxygen deficiency at high altitudes

Pulmonary disease and Congestive heart failurecaused by hypoxia

Acute anxiety

Fever, anemia

Early salicylate intoxication

Cirrhosis

Gram-negative sepsis


20/36

Compensation of Respiratory Alkalosis

Kidneys conserve hydrogen ion Excrete bicarbonate ion


21/36

Treatment of Respiratory Alkalosis

Treat underlying cause Breathe into a paper bag

IV Chloride containing solution

Cl- ions replace lost bicarbonate

ions


22/36

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


23/36

Metabolic acidosis (cont.)

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

Causes:

Increased alimentary or parenteral intake of acidor 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)


24/36

Symptoms of MetabolicAcidosis

Headache, lethargy

Nausea, vomiting, diarrhea Coma

Death


25/36

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)


26/36

Treatment of Metabolic Acidosis

IV lactate solution


27/36

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


28/36

Compensation for Metabolic Alkalosis

Alkalosis most commonly occurs

with renal dysfunction, so cant

count on kidneys

Respiratory compensation difficult

hypoventilation limited by

hypoxia


29/36

Symptoms of Metabolic Alkalosis

Respiration slow and shallow

Hyperactive reflexes ; tetany Often related to depletion of

electrolytes

Atrial tachycardia Dysrhythmias


30/36

Treatment of Metabolic Alkalosis

Electrolytes to replace those lost IV chloride containing solution

Treat underlying disorder


31/36

Diagnosis of Acid-BaseImbalances

1. Note whether the pH is low

(acidosis) or high (alkalosis)

2. Decide which value, pCO2orHCO3

-, is outside the normal

range andcould be thecauseof

the problem. If the cause is a

change in pCO2, the problem isrespiratory. If the cause is HCO3

-

the problem is metabolic.


32/36

3. Look at the value that doesnt correspond to

the observed pH change. If it is inside the

normal range, there is no compensation

occurring. If it is outside the normal range,the body is partially compensating for the

problem.


33/36

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)


34/36

Diagnosis

Metabolic acidosis With compensation


35/36


36/36

Acid Base Balance[1]Edit

Documents

Transcript of Acid Base Balance[1]Edit