PRESENTATION ON ABG Analysis BY SHYAMALIMA

ABG analysis, also known as Arterial Blood Gas analysis, is a test that measures the levels of oxygen and carbon dioxide in the blood, as well as the blood's pH level. It's typically performed on blood drawn from an artery, usually in the wrist or arm.

The test provides information on:

1. pH level (acidity or alkalinity of the blood)
2. Oxygen levels (PaO2)
3. Carbon dioxide levels (PaCO2)
4. Bicarbonate levels (HCO3-)
5. Oxygen saturation (SaO2)
ABG analysis is used to:

1. Diagnose and monitor respiratory and metabolic disorders, such as asthma, COPD, or diabetic ketoacidosis.
2. Evaluate oxygenation and ventilation status.
3. Monitor the effectiveness of oxygen therapy or mechanical ventilation.
4. Detect any electrolyte imbalances.

1. SHYAMALIMA DAS M.Sc NURSING (MEDICAL SURGICAL NURSING ) ABG ANALYSIS

2. LIFE IS STRUGGLE, NOT AGAINST SIN, NOT AGAINST MONEY, POWER….BUT AGAINST H+ IONS.

3. INTRODUCTION An advanced understanding of acid base physiology is as central to the practice of critical care medicine, as is an understanding of cardiac and pulmonary physiology. Recent advancement in the understanding of acid base physiology have occurred as the result of the application of basic physiochemical principles of adequeous solutions to blood plasma.

4. CONTINUE …. This analysis has revealed three independent variables that regulate PH in blood plasma these are Carbon dioxide, Relative electrolyte concentration Total weak acids concentrations

5. CONTINUE…. Systemic diseases are often accompanied by alterations in acid base regulation that may lead to life threatening conditions which are actually preventable by application of few basic principles.

6. FACT Acid Base disturbances involve one simple fact: The normal concentration or more specifically the activity of the Hydrogen ion (H+) has been altered.

7. DEFINITIONS HYDROGEN IONS : Vital to life. ACIDS : Substance which, when in solutions dissociate to form H+ and an Anion ( Cl -, SO4, HPO4). BASES : Substance which when in solutions combine with (remove) H+.

8. CONTINUE pH : Is the negative logarithm of the H+ ion activity which is equal to the H+ ion concentration when the activity coefficient is unity. Therefore, measurement of H+ provides an accurate and practical scale of acidity and alkalinity.

9. CONTINUE Acidaemia : Is defined as incraese in H+ and decrease In arterial pH. Acidosis: is process that acidifies body fluids, lowers plasma HCO3 and, if unopposed, will lead to fall of pH. Alkalemia : is defined as a decrease in H+ and a rise in arterial pH. Alkalosis: is process that alkalanizes body flids and if unopposed, leads to rise in pH.

10. BUFFERS Buffers: a solution containing substances that have the ability minimize changes in the pH when an acid or base is added to it. These are pH stabilizers. There are four major buffers: 1. Bicarbonate, 2. Plasma Proteins 3. haemoglobin 4. Phosphates

11. THE MAJOR BODY BUFFER SYSTEMS SITE BUFFER SYSTEM COMMENT ISF BICARBONATE PHOSPHATE PROTEIN For metabolic acids Not important because concentration too low BLOOD BICARBONATE HEMOGLOBIN PLASMA PROTEIN PHOSPHATE metabolic acids Carbon dioxide Minor buffer Concentration too low ICF PROTEINS PHOSPHATE Important Important URINE PHOSPHATE AMMONIA Titratable acidity Formation of NH4 BONE Calcium Carbonate In prolong metabolic acidosis

12. BICARBONATE BUFFER SYSTEM This is responsible for about 80% of extracellular buffering. It is the most important ECF buffer for metabolic acids but it can not buffer respiratory acid base disorders.

13. HEMOGLOBIN AS BUFFER Haemoglobin is quantitatively about 6 times more important than the plasma proteins as it is present in about twice the concentration. Hemoglobin has the capacity of isohydric exchange i.e the buffer system is converted to another more effective buffer exactly at the site where an increased buffering system is required. Deoxyhemoglobin is more effective buffer than oxyhemoglobin .

14. BONE AS BUFFER Bone consists of matrix within which specialised cells are dispersed. The matrix is composed of organic ( collagen and other proteins in ground substance) and inorganic hydroxyapatite crystals) components. Bone is the major CO2 reservoir in the body and contains carbonate equivalent to 5 moles of CO2 out of a total body CO2 stores of 6 moles.

15. Two prcoess that makes a bone as buffer: Ionic exchange Dissolution of bone crystal.

16. APPLICATIONS OF ABG ANALYSIS 1. To document respiratory failure and assess it’s severity. 2. To monitor patients on ventilators and assist in weaning 3. To assess acid base imbalance in critical cases. 4. To assess response to therapeutic interventions and mechanical ventilation 5. To assess pre op patients

17. ABG PROCEDURE SITE: Radial artey Dorsalis Pedis Femoral Brachial

18. CONTRAINDICATIONS RADIAL ARTERY BRACHIAL ARTERY Absent ulnar circulation Impaired circulation in the hand Underlying skeletal trauma AV fistula for dialysis Impaired circulation distally Fracture around the elbow, An AV fistula in the forearm

19. NORMAL ARTERIAL BLOOD GAS VALUES LAB TEST pH PaCO2 Bicarbonate PaO2 Conventional Units/ SI 7.35-7.45 35-45 21-28 80-100

20. SIMPLE ACID BASE DISORDERS: Simple acid base disorder – a single primary process of acidosis or alakalosis with or without compensation.

21. COMPENSATION The body always tries to normalize the pH so, pCo2 and HCO3 rise and fall together in simple disorders. Compensation never overcorrects pH Lack of compensation in an appropriate time defines a 2 nd disorder Require normally functioning lungs and kidneys

22. ACID BASE DISORDERS DISORDER PRIMARY RESPNSE COMPENSATORY RESPONSE METABOLIC ACIDOSIS H+ pH HCO3 pCo2 METABOLIC ALKALOSIS H+ pH HCO3 pCo2 RESPIRATORY ACIDOSIS H+ pH pCo2 HCO3 RESPIRATORY ALKALOSIS H+ pH pCo2 HCO3

23. Metabolic acidosis Metabolic acidosis is a serious electrolyte disorder characterized by an imbalance in the body's acid-base balance. Metabolic acidosis has three main root causes: Increased acid production, Loss of bicarbonate , Reduced ability of the kidneys to excrete excess acids.

24. SIGN AND SYMPOTOMS ACUTE CHRONIC Palpitations , Headache , Altered mental status, Decreased visual acuity, Nausea , Vomiting , Abdominal pain , Altered appetite Weight gain , Muscle weakness , Bone pain , J oint pain . Non-specific clinical symptoms but can be readily diagnosed by testing serum bicarbonate levels in patients with Chronic Kidney Disease (CKD)

25. ACUTE CHRONIC Kussmaul respirations, Diabetic ketoacidosis , Neurological: lethargy, stupor, coma, seizures Cardiac: Abnormal heart rhythms (e.g., ventricular tachycardia) and decreased response to epinephrine, both leading to low blood pressure Treatment:Bicarbonate therapy Dietary protein restriction, through ketoanalogue -supplemented vegetarian

26. Metabolic alkalosis Metabolic alkalosis is a metabolic condition in which the pH of tissue is elevated beyond the normal range (7.35–7.45). This is the result of decreased hydrogen ion concentration, leading to increased bicarbonate , or alternatively a direct result of increased bicarbonate concentrations.

27. CAUSES CHLORIDE RESPONSIVE (< 25mEq/L) CHLORIDE RESISTANT (>40mEq/L) Loss of hydrogen ions – Most often occurs via two mechanisms, either vomiting or via the kidney. Congenital chloride diarrhea Contraction alkalosis Diuretic therapy Posthypercapnia Cystic fibrosis Alkalotic agents Retention of bicarbonate Shift of hydrogen ions into intracellular space Hyperaldosteronism Excess glycyrrhizin consumption Bartter syndrome and Gitelman syndrome

28. CAUSES Low levels of magnesium in the blood Severely high levels of calcium in the blood Liddle syndrome 11β- hydroxylase deficiency 1 7α- hydroxylase deficiency

29. RESPIRATORY ACIDOSIS Respiratory acidosis is a state in which decreased ventilation ( hypoventilation ) increases the concentration of carbon dioxide in the blood and decreases the blood's pH .

30. CONTINUE Carbon dioxide is produced continuously as the body's cells respire, and this CO 2 will accumulate rapidly if the lungs do not adequately expel it through alveolar ventilation. Alveolar hypoventilation thus leads to an increased Pa CO 2 (a condition called hypercapnia ). The increase in Pa CO 2 in turn decreases the HCO 3 − / Pa CO 2 ratio and decreases pH.

31. CAUSES ACUTE CHRONIC Depression of the central respiratory center by cerebral disease or drugs, Inability to ventilate adequately due to neuromuscular disease (e.g., myasthenia gravis , amyotrophic lateral sclerosis , Guillain–Barré syndrome , muscular dystrophy ), Airway obstruction related to asthma or chronic obstructive pulmonary disease (COPD) exacerbation. Hypoventilation in COPD involves multiple mechanisms, including decreased responsiveness to hypoxia and hypercapnia , Increased ventilation-perfusion mismatch leading to increased dead space ventilation , Decreased diaphragm function secondary to fatigue and hyperinflation.

32. RESPIRATORY ALKALOSIS Respiratory alkalosis is a medical condition in which increased respiration elevates the blood pH beyond the normal range (7.35–7.45) with a concurrent reduction in arterial levels of carbon dioxide . This condition is one of the four primary disturbance of acid–base homeostasis .

33. The mechanism of respiratory alkalosis generally occurs when some stimulus makes a person hyperventilate. The increased breathing produces increased alveolar respiration, expelling CO 2 from the circulation. It alters the dynamic chemical equilibrium of CO2 in the circulatory system. Circulating hydrogen ions and bicarbonate are shifted through the carbonic acid (H 2 CO 3 ) intermediate to make more CO 2 via the enzyme carbonic anhydrase according to the following reaction: H C O 3 − + H + → H 2 C O 3 → C O 2 + H 2 O {\ displaystyle {\ rm {HCO_{3}^{-}+H^{+}\ rightarrow H_{2}CO_{3}\ rightarrow CO_{2}+H_{2}O}}}

34. CAUSES Respiratory alkalosis may be produced as a result of the following causes: Stress Pulmonary disorder Thermal insult High altitude areas Salicylate poisoning (aspirin overdose)

35. STEP BY STEP ANALYSIS OF ABG ANALYSIS

36. 1. LOOK AT THE pO2 (<80 mm Hg) and O2 saturation (<90%) for Hypoxemia. LOOK AT THE pH <7.35: acidosis >7.35: alkalosis 7.35-7.45: Normal/ mixed disorder

37. 3. LOOK AT pCo2 > 45mm Hg: Increased (Acidic) <35 mm Hg: Decreased ( Alkalotic )

38. 4. LOOK AT THE HCO3 > 26 mEq /L: Increased ( Alkalotic ) < 22 mEq /L: Decreased (Acidic)

39. 5. Determine the acid base disorder , match either the pCo2 or the HCO3 with the pH 6. Compensation are the Co2 or HCO3 of opposite type?

40. Is the compensation adequate? METABOLIC DISORDER pCo2 expected pCo2 measured ≠ pCo2 expected Mixed disorder RESPIRATORY DISORDER pH expected pHm ≠ pHe Mixed disorder

41. 7. Calculate the anion gap if it is more there is Metabolic acidosis AG= {Na+} – [ cl + HCO3] NORMAL AG is 12

42. 8. Does the anion gap explain the change in HCO3? Calculate Delta gap DG ratio = Normal Anion Gap- Measured Anion Gap/Normal Bicarbonate- measured bicarbonate. Normal DG is 0 to 0.4

43. PRACTICE QUESTIONS

44. Q1. 60yr old admitted with gluteal abscess ,known diabetic. ABG PH- 7.18 Na- 138 AG 23.1 Pco 2 18 K- 4.1 HCO 3 - 9 Cl-110 Ans -metabolic acidosis with partially compensated respiratory alkalosis.

45. Q2. 50 year old with chronic renal failure, smoker. ABG PH- 7.1 Na- 140 AG 23.1 Pco 2 -50 K- 5 HCO 3 - 5 Cl-105 Ans -metabolic acidosis with respiratory acidosis.

46. Q3. 35 year old collapsed on physical exertion was brought to hospital. ABG PH- 6.99 Na- 141 Pco 2 - 34 K- 6 HCO 3 - 8 Cl-105 Ans-hyperkalaemia with metabolic and respiratory acidosis.

47. O my God, provide us our daily bread, shelter, cloth and a normal pH!

48. THANK YOU