14. Arterial blood gas.pptx

14. Arterial blood gas.pptx

• 1.
  Arterial Blood Gas
• 2.
  Objectives •State the normalABG value ranges. •Define acidosis and alkalosis according to ABG values. •Name the four categories of acid-base disorders. •Understand how to use the ABG analyzer.
• 3.
  What is thepurpose of measuring acid-base? • Acid-base disorders are common in critically ill patients and assessment of acid-base status may indicate specific diagnoses or therapeutic interventions. • The presence of a metabolic acidosis should suggest hypoperfusion and prompt further assessment of adequacy of oxygen balance.
• 4.
  What is anABG? •Measures level of acidity, level of O2 and CO2. •Actual measurements are: pH, pO2 and pCO2. •To check how well your lungs are able to move O2 and remove CO2 from blood.
• 5.
  ABG analysis • Arterialblood gas analysis (ABG) should be available in the ICU. • In resource limited settings, ABG analysis may be available or frequent measurements not possible. • Consider use of end-tidal CO2 in conjunction with SpO2 and RR to make assessment, understanding the limitations.
• 6.
  What does itmeasure? •PaO2- partial pressure of O2 in blood (dissolved) •PaCO2- partial pressure of CO2 in blood •pH- hydrogen ions •HCO3- buffer that keeps the pH from becoming too acidic. •SatO2- amount of O2 in blood
• 7.
  ABG analysis  Benefits Limits • Measures pH, PaCO2, PaO2 • Informs about ventilation and acidosis • May also be used to measure lactate, haemoglobin, potassium • Invasive arterial puncture • Heparinized syringe • Rapid transfer (on ice if > 20 minutes to lab) • Blood gas analyser machine • Carbon monoxide level not detected on all machines.
• 8.
  Evaluation of Acid-BaseDisorders Analysis of acid-base disorders in seriously ill patients requires a systematic approach. Several processes possible: • Metabolic acidosis • Metabolic alkalosis • Respiratory acidosis • Respiratory alkalosis
• 9.
  Normal values No. CharacteristicsNormal range 1 pH 7.35-7.45 2 PCO2 35-45 mm Hg 3 PO2 80-100 mm Hg 4 O2 sat 95-100% 5 HCO3 22-26 mEq/l Note: PO2 is the amount of O2 dissolved in blood while O2 sat is the hemoglobin with O2 attached to each and measured in %.
• 10.
  Conditions No. Condition MetabolicRespiratory 1 Acidemia pH<7.35 PHCO3<22 PCO2>45 2 Alkalemia pH>7.45 PHCO3>26 PCO2>35
• 11.
  Key points • Thenormal pH of blood is 7.35-7.45. • If pH is < 7.35 its acidosis and if > 7.45 its alkalosis. • The normal value of pCO2 is 35-45 mm hg and HCO3 is 22- 26 mEq/l. • In respiratory disorders, the pH and pCO2 should be moving in opposite directions while HCO3 remains WNL. • In metabolic disorders, pH and HCO3 moves in the same direction with pCO2 WNL.
• 12.
  Questions •The normal pHrange of blood is ______ to ______. •Acidosis means pH is ______. •Alkalosis means pH is ______. •What four acid-base conditions are possible? •pH =7.30, HCO3=20 mEq/l and CO2= 40mm Hg • What is the condition?