2 What is an ABG Arterial Blood Gas Drawn from artery- radial, brachial, femoralIt is an invasive procedure.Caution must be taken with patient on anticoagulants.Arterial blood gas analysis is an essential part of diagnosing and managing the patient’s oxygenation status, ventilation failure and acid base balance.
3 What Is An ABG? pH [H+] PCO2 Partial pressure CO2 PO Partial pressure O2HCO3 BicarbonateBE Base excessSaO2 Oxygen Saturation
4 Acid/Base BalanceThe pH is a measurement of the acidity or alkalinity of the blood.no. of (H+) in the blood.The normal pH range isin an acidic state decreases the force of cardiac contractions, decreases the vascular response to catecholamines, and a diminished response to the effects and actions of certain medications.An alkalotic state interferes with tissue oxygenation and normal neurological and muscular functioning.
6 Buffers There are two buffers that work in pairs H2CO NaHCO3 Carbonic acid base bicarbonateThese buffers are linked to the respiratory and renal compensatory system
7 The Respiratory buffer response This triggers the lungs to either increase or decrease the rate and depth of ventilation , start to occur within 1-3 minutes
8 The Renal Buffer Response The kidneys excrete or retain bicarbonate(HCO3-).Renal system may take from hours to days to correct the imbalance.
9 ACID BASE DISORDER Res. Acidosis a pH less than 7.35 with a paco2 greater than 45 mmHg.
10 CausesCentral nervous system depression r/t medications such as narcotics, sedatives, or anesthesia.Impaired muscle function r/t spinal cord injury, neuromuscular diseases, or neuromuscular blocking drugs.Pulmonary disorders such as atelectasis, pneumonia, pneumothorax, pulmonary edemaMassive pulmonary embolusHypoventilation due to pain.
11 Management Increase the ventilation. Causes can be treated rapidly if not treated may need M.V
12 Respiratory alkalosis Psychological responses, anxiety or fear.PainIncreased metabolic demands such as fever, sepsis, pregnancy or thyrotoxicosis.Medications such as respiratory stimulants.RX: Resolve the underlying problemMonitor for respiratory muscle fatigue
13 Metabolic Acidosis Management: Treat the cause Bicarbonate less than 22mEq/L with a pH of less than 7.35.Renal failureDiabetic ketoacidosisManagement: Treat the causeHypoxia → Restore tissue perfusion to the hypoxic tissuesThe use of bicarbonate is indicated
14 Metabolic Alkalosis High PH, high HCO3, high CO2. Caused by: prolonged vomiting or NG suctioning, prolonged diuretic.
15 STEPS TO AN ABG INTERPRETATION Assess the pH –acidotic/alkaloticIf above 7.45 – alkaloticIf below 7.35 – acidotic
16 Contd….. Step 2: Assess the paCO2 level. pH decreases below 7.35, the paCO2 should rise.If pH rises above 7.45 paCO2 should fall.If pH and paCO2 moves in opposite direction – primary respiratory problem.
17 contd Step:2 Assess HCO3 value If pH increases the HCO3 should also increaseIf pH decreases HCO3 should also decreaseThey are moving in the same directionprimary problem is metabolic
18 Step 3 Assess pao2 < 80 mm Hg - Hypoxemia For a resp. disturbance : acute, chronicIf the change in paco2 is associated with the change in pH, the disorder is acute.In chronic process the compensatory process brings the pH to within the clinically acceptable range ( 7.30 – 7.50)
20 J is a 45 years old female admitted with the severe attack of asthma J is a 45 years old female admitted with the severe attack of asthma. She has been experiencing increasing shortness of breath since admission three hours ago. Her arterial blood gas result is as follows:pH : 7.22paCO2 : 55HCO3 : 25Follow the stepspH is low – acidosispaCO2 is high – in the opposite direction of the pH.Hco3 is Normal.Respiratory Acidosis
21 Mr. D is a 55 years old admitted with recurring bowel obstruction has been experiencing intractable vomiting for the last several hours. His ABG is:pH : 7.5paCO2 :42HCO3 : 33Metabolic alkalosis
22 COMPENSATIONA patient can be uncompensated or partially compensated or fully compensatedpH has returned within normal range- fully compensated though other values may be still abnormal
23 Mrs. H is admitted, he is kidney dialysis patient who has missed his last 2 appointments at the dialysis centre his ABG results:pH : 7.32paCo2 :HCO3 :Pao2 :Partially compensated metabolic Acidosis
24 Mr. K with COPD.His ABG is: pH : 7.35PaCO2 :HCO3 : 28PaO2 : 90Fully compensated Respiratory Acidosis
25 Mr. S is a 53 year old man presented to ED with the following ABG. pH : 7.51PaCO2 : 50HCO3 : 40Pao2 : 40 (21%O2)He has metabolic alkalosis
26 Precautions Excessive Heparin Decreases bicarbonate and PaCO2 Large Air bubbles not expelled from sample PaO2 rises, PaCO2 may fall slightly.Fever may lead to erroneous lab resultsCare must be taken to prevent bleeding
27 It’s not magic understanding ABG’s, it just takes a little practice!