ABG INTERPRETATION学习课件PPT

Acid/Base Relationship
H2O + CO2

H2CO3
HCO3 + H+
Normal ABG values
pH PCO2 7.35 – 7.45 35 – 45 mmHg
PO2
HCO3
80 – 100 mmHg
22 – 26 mmol/L
BE
SaO2
-2 - +2
>95%
Take home
What is an ABG
Arterial Blood Gas Drawn from artery- radial, brachial, femoral
It is an invasive procedure.
Caution must be taken with patient on anticoagulants.
Case Study No. 1
60 y/o male comes ER c/o SOB. Tachypneic, tachycardic, diaphoretic and Cyanotic. Dx acute resp. failure and ABG’s Show PaCO2 well below nl, pH above nl, PaO2 is very low. The blood gas document Resp. failure due to primary O2 problem.
Respiratory Component
function of the lungs
Carbonic acid H2CO3
Approximately 98% normal metabolites are in the form of CO2 CO2 + H2O H2CO3 excess CO2 exhaled by the lungs
HCO3 Bicarbonate BE SaO2 Base excess Oxygen Saturation
Acid/Base Relationship
This relationship is critical for homeostasis Significant deviations from normal pH ranges are poorly tolerated and may be life threatening Achieved by Respiratory and Renal systems
Helps differentiate oxygen deficiencies from primary ventilatory deficiencies from primary metabolic acid-base abnormalities
What Is An ABG?
pH [H+] PCO2 Partial pressure CO2 PO2 Partial pressure O2
Buffers
There are two buffers that work in pairs
H2CO3 Carbonic acid
NaHCO3 base bicarbonate
These buffers are linked to the respiratory and renal compensatory system
ABG INTERPRETATION
Debbie Sander PAS-II
Objectives
What’s an ABG? Understanding Acid/Base Relationship General approach to ABG Interpretation Clinical causes Abnormal ABG’s Case studies
Acidosis
pH < 7.35
Alkalosis
pH > 7.45
PCO2 > 45 HCO3 < 22
PCO2 < 35
HCO3 > 26
RespiO2 as an acid
failure of the lungs to exhale adequate CO2
Case Study No. 2
60 y/o male comes ER c/o SOB. Tachypneic, tachycardic, diaphoretic and Cyanotic. Dx acute resp. failure and ABG’s Show PaCO2 very high, low pH and PaO2 is moderately low. The blood gas document Resp. failure due to primarily ventilatory insufficiency.
Metabolic Component
Function of the kidneys
base bicarbonate Na HCO3
Process of kidneys excreting H+ into the urine and reabsorbing HCO3- into the blood from the renal tubules 1) active exchange Na+ for H+ between the tubular cells and glomerular filtrate 2) carbonic anhydrase is an enzyme that accelerates hydration/dehydration CO2 in renal epithelial cells
pH < 7.35 PCO2 > 45
CO2 + H2CO3 pH
Causes of Respiratory Acidosis
emphysema
drug overdose narcosis respiratory arrest airway obstruction