Lecture 8 - Arteial Blood Gas.pptx school

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1. Critical Care Medicine I Arterial Blood Gas EMMANUEL BAMFO

2. Arterial Blood Gas What is the usefulness of arterial blood gas (ABG) analysis? Provide information on a patient’s oxygenation, ventilation and acid-base balance status Helps in establishing diagnosis and severity of illness, e.g. respiratory failure, acid-base disorders from any severe illness Monitoring of a patient’s response to treatment e.g. effectiveness of oxygen therapy, ventilatory support, fluid and electrolyte replacement

3. Arterial Blood Gas Taking a blood sample for ABG analysis: Equipments; kits, labelled heparinized container (or syringe) Which arteries do we usually take the blood sample for ABG’s?; radial artery (most commonly used), brachial artery, femoral artery Allen's test; if using the radial artery Note patient’s temperature, amount of oxygen and ventilator settings at the time of taking the arterial blood sample If analysis is not going to be on-site, then sample must be transported in ice

4. Arterial Blood Gas Some possible complications associated with taking a sample for ABG analysis: Hemorrhage/hematoma Distal ischemia Infection Numbness Arterial spasm Injury to adjacent structures Compartment syndrome

5. Arterial Blood Gas Basic interpretation of ABG result: Acid-base balance is important for body cells and drugs to function properly The respiratory system controls acid-base balance by controlling amount of carbon dioxide (acid), whilst the kidneys (or metabolic system) controls acid-base balance by controlling amount of bicarbonate (base)

6. Basic Parameters of an ABG Result Sheet Parameter Normal Range pH 7.35 - 7.45 PaCO2 35 - 45 mmHg; ↑ PaCO2 indicates acidosis and ↓ PaCO2 indicates alkalosis HCO3 22 - 26 mmol/L; ↓ HCO3 indicates acidosis and ↑ HCO3 level indicates alkalosis PaO2 80 - 100 mmHg; inc. indicates hyperventilation & decr . indicates hypoxaemia SaO2 95 - 100%

7. Arterial Blood Gas Basic interpretation of ABG result: Other parameters that may be measured on an ABG result sheet; Serum electrolytes, hematocrit/Hb, lactate, base excess, anion gap, blood glucose, urea kPa may be used instead of mmHg mEq/L may be used instead of mmol/L

8. Arterial Blood Gas Basic interpretation of an ABG result: What is the pH; normal, acidosis or alkalosis? What is the PaCO2 and HCO3; is the acidosis or alkalosis of respiratory or metabolic origin? What is the SaO2 and PaO2; is there hypoxemia? Is there compensation; respiratory compensation or metabolic compensation?

9. Arterial Blood Gas

10. Arterial Blood Gas Q1: Jane Doe is a 45-year-old admitted to the emergency unit with a severe asthma attack. She has been experiencing increasing shortness of breath since admission three hours ago. Her ABG result is as follows: pH - 7.22; PaCO2 - 55mmHg; HCO3 - 25mmol/L What is the problem?

11. Arterial Blood Gas Q2: John Doe is a 55-year-old, admitted with a recurring bowel obstruction. He has been experiencing intractable vomiting for the last several hours. Here is his ABG result: pH - 7.50; PaCO2 - 5.6 kPa; HCO3 - 4.4 kPa What is the problem?

12. Arterial Blood Gas Q3: A 69 year old lady is brought to the hospital after a witnessed cardiac arrest, resuscitated, with ETT in-situ ventilated with 60% oxygen via a mechanical ventilator GCS - 3/15; HR - 118beats/min; BP - 140/100 mmHg ABG results as follows: FiO2 - 0.6; pH - 7.10; PaCO2 - 46.5mmHg; PaO2 - 56.2mmHg; HCO3 - 23mmol/L

13. Arterial Blood Gas Q4: 33yr old John Doe at the ICU on mechanical ventilatory support via ETT and sedated; TV - 680mls, MV - 9.51mls, SpO2 - 100% on FiO2 - 0.35, RR - 14; BP - 122/68mmHg, HR - 86 beats/min ABG results: pH - 7.6; PaO2 - 120mmHg; PaCO2 - 17.2mmHg; HCO3 - 24mmol/L What is the problem and what is your solution?

14. Arterial Blood Gas Q5.

15. Arterial Blood Gas Q6.