Vent and Gas (Lec) ➢ You have a primary acid-base disorder and
a secondary acid-base disorder.
Lesson 3: Arterial Blood Gas
➢ Primary: Problem.
Acid-Base Balance ➢ Secondary: Compensation
➢ Arrows in metabolic, abnormality and
− Acid-base homeostasis in man is compensation: Opposite.
accomplished by the maintenance of ➢ Arrows in respiratory: Same
systemic arterial pH within a narrow range
despite acid & alkaline loads from the daily Respiratory Acidosis:
intake & degradation of foods,
➢ the problem is an increase in your carbon
− Body pH is protected by 3 mechanisms: dioxide level, so the compensation in your
1. Buffers kidney should be alkalosis (metabolic
➢ Buffer mechanism. acidosis), there should be an increase in
2. Pulmonary regulation of PaCO2 your bicarbonate level.
➢ Lungs via regulation of carbon ➢ There’s an increase in your carbon dioxide
dioxide. level.
3. Renal reabsorption & excretion of HCO3 ➢ Compensatory: metabolic acidosis there
(bicarbonate) & excretion of acid. should be an increase in your bicarbonate.
Two types of acid-base disorders: Respiratory Alkalosis:
1. Metabolic ➢ The problem is there is a decrease in your
− Characterized by primary disturbance carbon dioxide level. The compensation
in the concentration of HCO3. should be metabolic acidosis.
➢ Problem is mainly in the Kidney, the ➢ The primary abnormality: Decreased carbon
main problem is in your bicarbonate dioxide level.
(HCO3). ➢ Compensation: Metabolic acidosis, the
2. Respiratory should be a decrease in your bicarbonate.
− Primarily offers PaCO2.
➢ Usually, the problem is in your carbon Kung ang problem is alkalosis dapat ang
dioxide level. compensatory acid-base should be acidosis.
Abnormality Compensation In metabolic acid-base problem:
Respiratory Metabolic Acidosis:
↑ HCO3
Acidosis ↑ CO2 (Metabolic ➢ The problem is a decrease in your
Alkalosis) bicarbonate.
↓ HCO3 ➢ The compensation is respiratory alkalosis.
Alkalosis ↓ CO2 (Metabolic ➢ There should be a decrease in your carbon
Acidosis) dioxide level.
Metabolic
↓ CO2 Metabolic Alkalosis:
Acidosis ↓ HCO3 (Respiratory ➢ Primary problem is an increase in your
Alkalosis) bicarbonate level.
↑ CO2 ➢ The compensation should be respiratory
Alkalosis ↑ HCO3 (Respiratory
acidosis.
Acidosis)
➢ There’s an increase in your carbon dioxide
level.
➢ In every acid-base disturbance, there’s a
compensatory acid-base disturbance also.
, Clinical & laboratory parameters in acid- Components of Arterial Blood Gas (ABG)
base disorders
pH
1. Careful history and physical examination
− Measurement of alkalinity and acidity based
➢ You have to interpret the laboratory in
on Hydrogen ions present.
combination with patients.
2. Electrolytes & arterial blood gas (ABG) − Normal range is 7.35 – 7.45
3. Evaluate anion gap ➢ Acidosis: Anything BELOW the normal
➢ Especially, among patients having range (Below 7.35)
metabolic acidosis to be able to know ➢ Alkalosis: Anything ABOVE the normal
what type of metabolic acidosis and range (Above 7.45)
what are the possible cause of the PaCO2
metabolic acidosis.
− Partial pressure of CO2 dissolved in blood.
Anion gap = Na – (Cl + HCO3) − Normal range is 35-45 mmHg
➢ Anion gap is computed by serum sodium − Opposite pattern of pH and bicarbonate
minus chloride plus bicarbonate. ➢ Alkalosis: Anything BELOW the normal
➢ Pwedeng ilabas sa exam. range (Below 35 mmHg)
➢ Acidosis: Anything ABOVE the normal
Normal value of anion gap: range (Above 45 mmHg)
Normal value = 10-12 meq/L PaO2
➢ In this anion gap, usually you have to take
− Partial pressure of O2 dissolved in arterial
note whether the anion gap is elevated
blood.
meaning Positively an anion gap or Normal
anion gap. Normal is 10-12. − Normal range is 80-100 mmHg
➢ If you have metabolic acidosis you have to Interpretation Range
compute for anion gap because you have to Adequate Oxygenation 80-100 mmHg
differentiate whether this is: More than Adequate > 100 mmHg
1. Anion gap metabolic acidosis Oxygenation (more than 100)
➢ Ibig sabihin may acid tas anion gap < 80 mmHg
Hypoxemia
niya is 12 (less than 80)
2. Non-anion-gap metabolic acidosis <80-60
Mild Hypoxemia
➢ Ibig sabihin metabolic acidosis pero (less than 80 to 60)
anion gap level niya is normal. <60-40
Moderate Hypoxemia
(less than 60 to 40)
Arterial Blood Gas (ABG) <40
Severe Hypoxemia
(less than 40)
− Arterial blood gases are an invaluable tool in
assessing ventilation, acid-base balance HCO3-
and oxygenation.
➢ Take note, sa ABG interpretation, there − Amount of bicarbonate in the bloodstream
are 2 interpretation: the acid-base and − Normal range is 22-26 meq/L
oxygenation. ➢ Acidosis: Anything BELOW the normal
− Results should be correlated with good range (Below 22 meq/L)
clinical data. ➢ Alkalosis: Anything ABOVE the normal
− Treat the patient, not the lab results! range (Above 26 meq/L)
− Accurate history and physical examination.
➢ ABG should be paired with these two.
a secondary acid-base disorder.
Lesson 3: Arterial Blood Gas
➢ Primary: Problem.
Acid-Base Balance ➢ Secondary: Compensation
➢ Arrows in metabolic, abnormality and
− Acid-base homeostasis in man is compensation: Opposite.
accomplished by the maintenance of ➢ Arrows in respiratory: Same
systemic arterial pH within a narrow range
despite acid & alkaline loads from the daily Respiratory Acidosis:
intake & degradation of foods,
➢ the problem is an increase in your carbon
− Body pH is protected by 3 mechanisms: dioxide level, so the compensation in your
1. Buffers kidney should be alkalosis (metabolic
➢ Buffer mechanism. acidosis), there should be an increase in
2. Pulmonary regulation of PaCO2 your bicarbonate level.
➢ Lungs via regulation of carbon ➢ There’s an increase in your carbon dioxide
dioxide. level.
3. Renal reabsorption & excretion of HCO3 ➢ Compensatory: metabolic acidosis there
(bicarbonate) & excretion of acid. should be an increase in your bicarbonate.
Two types of acid-base disorders: Respiratory Alkalosis:
1. Metabolic ➢ The problem is there is a decrease in your
− Characterized by primary disturbance carbon dioxide level. The compensation
in the concentration of HCO3. should be metabolic acidosis.
➢ Problem is mainly in the Kidney, the ➢ The primary abnormality: Decreased carbon
main problem is in your bicarbonate dioxide level.
(HCO3). ➢ Compensation: Metabolic acidosis, the
2. Respiratory should be a decrease in your bicarbonate.
− Primarily offers PaCO2.
➢ Usually, the problem is in your carbon Kung ang problem is alkalosis dapat ang
dioxide level. compensatory acid-base should be acidosis.
Abnormality Compensation In metabolic acid-base problem:
Respiratory Metabolic Acidosis:
↑ HCO3
Acidosis ↑ CO2 (Metabolic ➢ The problem is a decrease in your
Alkalosis) bicarbonate.
↓ HCO3 ➢ The compensation is respiratory alkalosis.
Alkalosis ↓ CO2 (Metabolic ➢ There should be a decrease in your carbon
Acidosis) dioxide level.
Metabolic
↓ CO2 Metabolic Alkalosis:
Acidosis ↓ HCO3 (Respiratory ➢ Primary problem is an increase in your
Alkalosis) bicarbonate level.
↑ CO2 ➢ The compensation should be respiratory
Alkalosis ↑ HCO3 (Respiratory
acidosis.
Acidosis)
➢ There’s an increase in your carbon dioxide
level.
➢ In every acid-base disturbance, there’s a
compensatory acid-base disturbance also.
, Clinical & laboratory parameters in acid- Components of Arterial Blood Gas (ABG)
base disorders
pH
1. Careful history and physical examination
− Measurement of alkalinity and acidity based
➢ You have to interpret the laboratory in
on Hydrogen ions present.
combination with patients.
2. Electrolytes & arterial blood gas (ABG) − Normal range is 7.35 – 7.45
3. Evaluate anion gap ➢ Acidosis: Anything BELOW the normal
➢ Especially, among patients having range (Below 7.35)
metabolic acidosis to be able to know ➢ Alkalosis: Anything ABOVE the normal
what type of metabolic acidosis and range (Above 7.45)
what are the possible cause of the PaCO2
metabolic acidosis.
− Partial pressure of CO2 dissolved in blood.
Anion gap = Na – (Cl + HCO3) − Normal range is 35-45 mmHg
➢ Anion gap is computed by serum sodium − Opposite pattern of pH and bicarbonate
minus chloride plus bicarbonate. ➢ Alkalosis: Anything BELOW the normal
➢ Pwedeng ilabas sa exam. range (Below 35 mmHg)
➢ Acidosis: Anything ABOVE the normal
Normal value of anion gap: range (Above 45 mmHg)
Normal value = 10-12 meq/L PaO2
➢ In this anion gap, usually you have to take
− Partial pressure of O2 dissolved in arterial
note whether the anion gap is elevated
blood.
meaning Positively an anion gap or Normal
anion gap. Normal is 10-12. − Normal range is 80-100 mmHg
➢ If you have metabolic acidosis you have to Interpretation Range
compute for anion gap because you have to Adequate Oxygenation 80-100 mmHg
differentiate whether this is: More than Adequate > 100 mmHg
1. Anion gap metabolic acidosis Oxygenation (more than 100)
➢ Ibig sabihin may acid tas anion gap < 80 mmHg
Hypoxemia
niya is 12 (less than 80)
2. Non-anion-gap metabolic acidosis <80-60
Mild Hypoxemia
➢ Ibig sabihin metabolic acidosis pero (less than 80 to 60)
anion gap level niya is normal. <60-40
Moderate Hypoxemia
(less than 60 to 40)
Arterial Blood Gas (ABG) <40
Severe Hypoxemia
(less than 40)
− Arterial blood gases are an invaluable tool in
assessing ventilation, acid-base balance HCO3-
and oxygenation.
➢ Take note, sa ABG interpretation, there − Amount of bicarbonate in the bloodstream
are 2 interpretation: the acid-base and − Normal range is 22-26 meq/L
oxygenation. ➢ Acidosis: Anything BELOW the normal
− Results should be correlated with good range (Below 22 meq/L)
clinical data. ➢ Alkalosis: Anything ABOVE the normal
− Treat the patient, not the lab results! range (Above 26 meq/L)
− Accurate history and physical examination.
➢ ABG should be paired with these two.
