Arterial Blood gases

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is there a problem with this upload? iam getting a fileof 1.8mb with filename extension .pptx which does not-open in powerpoint, please help

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extremely helpful presentation.plz be kind n mail it ti drdeepak.katyal@gmail.com thanks sir

By: drdeepak.katyal (49 month(s) ago)

abg analysis has been my biggest weakness theoritically n in practical life as well.i m working as a cardiology SR in Gurgaon n am prepring4 DM cardiology entrance.ur presentation will help me in all d ways.thanx

 
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Presentation Transcript

CLINICAL INTERPRETATION OF ABG : 

CLINICAL INTERPRETATION OF ABG Dr Vishram Buche Director, NICU Central InDIA’S CHILD hOSPITAL & Research INSTITUTE NAGPUR INDIA

Slide 2: 

Central India’s C H I L D HOSPITAL & Research Institute

Slide 3: 

pH PCO2 HCO3 PO2

Slide 4: 

…A respiratory component …A respiratory acid …Moves opposite to the direction of pH. …A metabolic component …It is a base (Metabolic) …Moves in the same direction of pH. …Moves in same direction... Primary disorder …Moves in opposite direction …Mixed Disorder CO2 HCO3 CO2 HCO3 Facts about Acid-Base balance…… Remember format……….. pH………….. 7.4 (7.35 - 7.45) PCO2 …….…40 (35 -45) HCO3 ……… 24 (22 -26)

Slide 5: 

Getting a Feel Of Blood Gases

Slide 6: 

Primary lesion compensation pH HCO3 CO2 METABOLIC ACIDOSIS HYPER VENTILATION HCO3 changes pH in same direction Low Alkali LOW HCO3 LOW pH LOW pCO2 (compensated)

Slide 7: 

Primary lesion compensation pH HCO3 CO2 METABOLIC ALKALOSIS HYPO VENTILATION BICARB CHANGES pH in same direction HIGH HCO3 HIGH pH HIGH pCO2 (compensated) High Alkali

Slide 8: 

CO 2 CHANGES pH in opposite direction Primary lesion compensation pH CO 2 BICARB Respiratory acidosis HIGH pCO2 LOW pH HIGH HCO3 (compensated) High CO2

Slide 9: 

Primary lesion compensation pH CO 2 BICARB Respiratory alkalosis Low CO2 CO 2 CHANGES pH in opposite direction LOW pCO2 HIGH pH LOW HCO3 (compensated)

Slide 10: 

Body’s physiologic response to Primary disorder in order to bring pH towards NORMAL limit Full compensation Partial compensation No compensation…. (uncompensated) BUT never overshoots, If a overshoot pH is there, Take it granted it is a MIXED disorder Compensation….

Slide 11: 

Remember……. Respiratory compensation is always FAST …12-24 hrs Metabolic compensation is always SLOW...5 -7 days Respiratory disturbances are better compensated than metabolic ones. Predictable in……… Metabolic acidosis. Un-predictable in……. metabolic alkalosis.

How to identify the type of compensation…..? : 

How to identify the type of compensation…..? pH HCO3 CO2 7.20 15 40 7.25 15 30 7.37 15 20 Un Compensated Partially Compensated Fully Compensated (pH abnormal) (pH in normal range)

Slide 13: 

COMPENSATION LIMITS Compensation Beyond Limits………….. Mixed disorder

Slide 14: 

xygenation

Slide 17: 

…To calculate A-a gradient…. Is the baby hypoxic? Type and severity of Hypoxia. …Relationship of PaO2 and FiO2? FiO2 X 5 = Expected PaO2 …Whether PaO2 is appropriate for the given FiO2? …Is the O2 content (CaO2) enough to prevent hypoxia?

Alveolar-arterial O2 Difference : 

Alveolar-arterial O2 Difference * When FiO2 = 21 % : PiO2 = (760-45) x .21= 150 mmHg O2 CO2  (calculated)PAO2 = 150 – 1.2 (PCO2) = 150 – 1.2  40 = 150 – 50 = 100 mm Hg (measured) PaO2 = 90 mmHg ………..PAO2 – PaO2 = ? PAO2 = PiO2* -(PCO2/0.8) PAO2 – PaO2 = 10 mmHg PaO2 PAO2 Classify Respiratory Failure Ventilation–perfusion mismatch ……FiO2 dependant derivation

Alveolar-arterial Difference : 

Alveolar-arterial Difference O2 CO2 Alveolar – arterial G. 100 - 45 = 55 ……………….Wide A-a Oxygenation Failure Wide Gap PCO2 = 40 PaO2 = 45 PAO2 = 150 – 1.2 (40) = 150 - 50 = 100 Ventilation Failure Normal Gap PCO2 = 80 PaO2 = 45 PAO2 = 150-1.2(80) = 150-100 = 50 Alveolar arterial G. 50 – 45 = 5 …………….Normal A-a

Slide 20: 

20 × 5 = 100 Expected PaO2 = FiO2 × 5 = PaO2 Normal

Slide 21: 

It is essential to have ELECTROLYTES for crucial interpretation of ABG. esp. Na, Cl, K We always correlate PaO2 with FiO2 BUT…………………………. never forget to correlate with PaCO2

Slide 22: 

It Is Incomplete without…… FiO2 Hb ct The essentials of Blood gas… pH

Slide 23: 

Now that I have this data, what does it mean? ----- XXXX Diagnostics ------ Blood Gas Report 248 05:36 Jul 22 2000 Pt ID 2570 / 00 Measured 37.0o C pH 7.463 pCO2 44.4 mm Hg pO2 113.2 mm Hg Corrected 38.6o C pH 7.439 pCO2 47.6 mm Hg pO2 123.5 mm Hg Calculated Data TPCO2 49 HCO3 act 31.1 mmol / L HCO3 std 30.5 mmol / L BE 6.6 mmol / L O2 CT 14.7 mL / dl O2 Sat 98.3 % ct CO2 32.4 mmol / L pO2 (A - a) 32.2 mm Hg pO2 (a / A) 0.79 Entered Data Temp 38.6 oC ct Hb 10.5 g/dl FiO2 30.0 % output

Slide 24: 

Experience is the ability to make the same mistake repeatedly with increasing confidence

Slide 25: 

The Anatomy of a Blood Gas Report -----XXXX Diagnostics----- Blood Gas Report 328 03:44 Feb 5 2006 Pt ID 3245 / 00 Measured 37.0 0C pH 7.452 pCO2 45.1 mm Hg pO2 112.3 mm Hg Corrected 38.6 0C pH 7.436 pCO2 47.6 mm Hg pO2 122.4 mm Hg Calculated Data HCO3 act 31.2 mmol / L HCO3 std 30.5 mmol / L B E 6.6 mmol / L O2 ct 15.8 mL / dl O2 Sat 98.4 % ct CO2 32.5 mmol / L pO2 (A -a) 30.2 mm Hg  pO2 (a/A) 0.78 Entered Data Temp 38.6 0C FiO2 30.0 % ct Hb 10.5 gm/dl Measured values… most important Temperature Correction : Is there any value to it ? Calculated Data : Which are useful one? Entered Data : Important

Slide 26: 

Uncorrected pH & pCO2 are reliable reflections of in-vivo acid base status Temperature correction of pH & pCO2 do not affect calculated bicarbonate “ There is no scientific basis ... for applying temperature corrections to blood gas measurements…” Shapiro BA, OTCC, 1999. pCO2 reference points at 37o C are well established as a reliable reflectors of alveolar ventilation Reliable data on DO2 and oxygen demand are unavailable at temperatures other than 37o C Measured values should be considered And Corrected values should be discarded

Slide 27: 

Bicarbonate is calculated on the basis of the Henderson equation: [H+] = 24 pCO2 / [HCO3-] or for the Mathematically inclined… Act Bicarbonate: -----XXXX Diagnostics----- Blood Gas Report 328 03:44 Feb 5 2006 Pt ID 3245 / 00 Measured 37.0 0C pH 7.452 pCO2 45.1 mm Hg pO2 112.3 mm Hg Corrected 38.6 0C pH 7.436 pCO2 47.6 mm Hg pO2 122.4 mm Hg Calculated Data HCO3 act 31.2 mmol / L HCO3 std 30.5 mmol / L B E 6.6 mmol / L O2 ct 15.8 mL / dl O2 Sat 98.4 % ct CO2 32.5 mmol / L pO2 (A -a) 30.2 mm Hg  pO2 (a/A) 0.78 Entered Data Temp 38.6 0C FiO2 30.0 % ct Hb 10.5 gm/dl

Slide 28: 

-----XXXX Diagnostics----- Blood Gas Report 328 03:44 Feb 5 2006 Pt ID 3245 / 00 Measured 37.0 0C pH 7.452 pCO2 45.1 mm Hg pO2 112.3 mm Hg Corrected 38.6 0C pH 7.436 pCO2 47.6 mm Hg pO2 122.4 mm Hg Calculated Data HCO3 act 31.2 mmol / L HCO3 std 30.5 mmol / L B E 6.6 mmol / L O2 ct 15.8 mL / dl O2 Sat 98.4 % ct CO2 32.5 mmol / L pO2 (A -a) 30.2 mm Hg  pO2 (a/A) 0.78 Entered Data Temp 38.6 0C FiO2 30.0 % ct Hb 10.5 gm/dl

Slide 29: 

Oxygenation Parameters: /limitations O2 Content of blood: (Hb x1.34x O2 Sat + 0.003x Dissolved O2 ) Remember Hemoglobin Oxygen Saturation: ( remember this is calculated …error prone) Alveolar / arterial gradient: ( classify respiratory failure) Arterial / alveolar ratio: Proposed to be less variable Same limitations as A-a gradient -----XXXX Diagnostics----- Blood Gas Report 328 03:44 Feb 5 2006 Pt ID 3245 / 00 Measured 37.0 0C pH 7.452 pCO2 45.1 mm Hg pO2 112.3 mm Hg Corrected 38.6 0C pH 7.436 pCO2 47.6 mm Hg pO2 122.4 mm Hg Calculated Data HCO3 act 31.2 mmol / L HCO3 std 30.5 mmol / L B E 6.6 mmol / L O2 ct 15.8 mL / dl O2 Sat 98.4 % ct CO2 32.5 mmol / L pO2 (A -a) 30.2 mm Hg  pO2 (a/A) 0.78 Entered Data Temp 38.6 0C FiO2 30.0 % ct Hb 10.5 gm/dl

Slide 30: 

A Systematic and Pointed ………. approach

Slide 31: 

Steps for Successful Blood Gas Analysis 7

Slide 32: 

1. 2. Look at pH? 3. Who is the culprit ?...Metabolic / Respiratory 4. If respiratory…… acute and /or chronic 5. If metabolic acidosis, Anion gap ↑ed and/or normal or both? Is more than one disorder present? Correlate clinically Consider the clinical settings! Anticipate the disorder 7 steps to analyze ABG

Slide 33: 

Look at the pH Is the patient acidemic pH < 7.35 or alkalemic pH > 7.45 If pH = 7.4 …… Normal Mixed or Fully compensated Step 2

Step 3 ……. CULPRIT? : 

Step 3 ……. CULPRIT? HCO3…… METABOLIC > 26 ….. Met. Alkalosis < 22 ……Met. Acidosis PCO2 ……RESPIRATORY > 45 …… Resp. Acidosis < 35 …… Resp. Alkalosis HCO3 = Base Normal…22-26 CO2 = ACID Normal…35-45

Slide 36: 

If there is a primary Respiratory disturbance, is it acute ? .08 change in pH ( Acute ) .03 change in pH (Chronic) 10 mm Change PaCO2 = Remember………… relation of CO2 and pH Step 4 …

Slide 37: 

PCO2 of 10 Acute change .08 Chronic change .03 pH Step 4 continued…

Slide 38: 

7.60 20 7.50 30 7.40 40 7.30 50 7.20 60 7.10 70 pH PaCO2 Acute respiratory change pH Last two digits 80 – PaCO2 Step 4 continued…

Slide 39: 

Step 4 continued… RESPIRATORY disorders… Expected HCO3 for a Change in CO2 ......... 1 2 3 4 Acidosis…. (expected) HCO3 = 0.1 x ∆ CO2 Alkalosis…. (expected) HCO3 = 0.2 x ∆ CO2 Acidosis…. (expected) HCO3 = 0.35 x ∆ CO2 Alkaosis…. (expected) HCO3 = 0.4 x ∆ CO2 Acute respiratory Chronic respiratory

Slide 40: 

If it is a primary Metabolic disturbance, whether respiratory compensation appropriate? For metabolic acidosis:Expected PCO2 = (1.5 x [HCO3]) + 8 + 2 (Winter’s equation) For metabolic alkalosis: Expected PCO2 = 6 mm… for 10 mEq. rise in Bicarb. ………UNCERTAIN COMPENSATION CO2 is equal to Last two digits of pH Remember If : Suspect ............. actual PaCO2 is more than expected additional...respiratory acidosis actual PaCO2 is less than expected additional...respiratory alkalosis Step 5

Slide 41: 

If metabolic acidosis is there How is anion gap ? Is it wide ... Na - (Cl-+ HCO3-) = Anion Gap usually <12 If >12, Anion Gap Acidosis : M ethanol U remia D iabetic Ketoacidosis P araldehyde I nfection (lactic acid) E thylene Glycol S alicylate Common pediatric causes Lactic acidosis Metabolic disorders Renal failure Step 5 cont.

Step 6… : 

Step 6… Is more than one DISORDER present?

Mixed Acid-Base Disorders : Clues : 

Mixed Acid-Base Disorders : Clues -- Clinical history -- pH normal, abnormal PCO2 n HCO3 -- PCO2 n HCO3 moving opposite directions -- Degree of compensation for primary disorder is inappropriate -- Find Delta Gap

Metabolic Acidosis……. + additional disorders : 

Metabolic Acidosis……. + additional disorders Equivalent rise of AG and Fall of HCO3…… ….Pure Anion Gap Metabolic Acidosis Discrepancy…….. in rise & fall + Non AG M acidosis, + M Alkalosis

PURE Anion Gap Acidosis + : 

PURE Anion Gap Acidosis + Delta gap = HCO3 + ∆ AG Delta Gap = 24….Pure AG acidosis < 24 = non AG acidosis (+ AG M Acidosis) > 24 = metabolic alkalosis (+ AG M Acidosis)

Slide 46: 

N-HCO3 = 24, N-Anion Gap = 12 Delta Gap = HCO3 + ∆AG e.g. if HCO3= 12, AG = 24, ∆ AG = 12 Delta gap = 12 + 12 = 24 ….Pure AG Metabolic Acidosis Delta Gap = 24 ……AG met Acidosis < 24 ….. + Non AG Mac > 24 ….. + Meta. Alkalosis N-HCO3 = 24, N-Anion Gap = 12 Delta Gap = HCO3 + ∆ AG e.g. if HCO3 = 12, AG = 20, ∆ AG = 8 Delta Gap = 12 + 8 = 20, < 24 …AG + Non AG metabolic Acidosis N-HCO3 = 24, N-Anion Gap = 12 Delta Gap = HCO3 + ∆ AG e.g. if HCO3 = 12, AG = 30, ∆ AG = 18 Delta Gap = 12 + 18 = 30 > 24 ….AG + metabolic Alkalosis

Double……… triple……………. Quadruple…….??? : 

Double……… triple……………. Quadruple…….???

Slide 48: 

th step Clinical correlation 7

Validity of ABG report… a lab error : 

Validity of ABG report… a lab error e.g. pH = 7.30, PCO2 = 38, HCO3 = 30 By Henderson-Hasselbach H+ = 24 x pCO2/HCO3 = 24 x (38/30) = 30 80 - last two digit pH = H+ 80 - H+ = last two digit pH (after 7) pH should be 7.50

Slide 50: 

Ready Chart………

It’s not magic understanding ABG’ s, it just takes a little practice! : 

It’s not magic understanding ABG’ s, it just takes a little practice!

Slide 52: 

Experience is a wonderful thing. It enables you to recognize a mistake when you make it (again).

Slide 53: 

pH............7.34 PaCO2.....33.9 HCO3.......18.2 Partially compensated Metabolic Acidosis pH = 7.4 PaCO2 = 40 HCO3 = 24 9 months old male with Acute Enteritis….. Partially compensated Metabolic Acidosis

Slide 54: 

pH.............7.55 PaCO2.....49.0 HCO3.......48.2 Partially compensated Metabolic Alkalosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 55: 

pH............7.44 PaCO2.....27.0 HCO3.......18.1 Fully compensated Respiratory Alkalosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 56: 

pH............7.28 PaCO2.....79.5 HCO3.......37.1 Partially compensated Respiratory Acidosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 57: 

pH............7.51 PaCO2.....39.4 HCO3.......31.3 Uncompensated Metabolic Alkalosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 58: 

pH............7.39 PaCO2.....39.0 HCO3.......23.4 Normal A.B.G. pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 59: 

pH............7.25 PaCO2.....58.5 HCO3.......25.1 Uncompensated Respiratory Acidosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 60: 

pH............7.46 PaCO2.....34.0 HCO3.......26.0 Uncompensated Respiratory Alkalosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 61: 

pH..............7.37 PaCO2.......75.1 HCO3.........42.6 Fully compensated Respiratory Acidosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 62: 

pH..............7.52 PaCO2.......31.0 HCO3.........29.4 Combined Alkalosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 63: 

pH..............7.08 PaCO2.......54.0 HCO3.........18.0 Combined Acidosis pH = 7.4 PaCO2 = 40 HCO3 = 24

Slide 64: 

▲Respiratory Alkalosis What is the Diagnosis ? pH ………7.563 PCO2 ….19.8 HCO3 ….18.7 For a 10 mm change of PCO2 pH changes by 0.08 ……Acute by 0.03 ……Chronic Is it acute / Chronic? Acute Respiratory Alkalosis

THANKS : 

THANKS : vbuche@gmail.com