PLT COLLEGE, INC.Bayombong, Nueva Vizcaya

Institute of Health Sciences –College of Nursing

Nursing Care Management (NCM 104)Curative and Rehabilitative Nursing

(Julie Ann T. Garnace, RN- Instrucor)

Critical Facts about Systematic ABG Analysis

How to do ABG analysis incredibly quick and accurate? Follow the following steps:Step I. Remember the Normal Values

Blood pH 7.35 – 7.45paO2 80 – 100 mmHgpaCO2 35 – 45 mmHgHCO3 22 – 26 mEq/LO2 Saturation 95 – 100%BE/BD (Base Excess/Base Deficit) -2 to +2

Step II. Look at the pH. Does it indicate presence of academia, or alkalemia, or normal pH?

pH low (below 7.35) ACIDOSISpH high (below 7.45) ALKALOSIS

MIDDLE RANGE7.40

Acid ← 7.35 ---------------------------------------7.45 → Base(ACIDOSIS) (ALKALOSIS)

e.g. pH 7.31 (low) ACIDOSISpH 7.48 (high) ALKALOSIS

Please do these exercises. Identify whether the pH is Normal, ACIDOTIC or ALKALOTIC1. 7.41 __________________________2. 7.32 __________________________3. 7.50 __________________________

Step III. Look at the PaCO2

PaCO2 is the RESPIRATORY INDICATOR. CO2 acts as an ACID. When CO2 combines with plasma, CARBONIC ACID is formed (CO2 + H2O = H2CO3).

PaCO2 high (above 45 mmHg) RESPIRATORY ACIDOSISPaCO2 low (below 35 mmHg) RESPIRATORY ALKALOSIS

MIDDLE RANGE40

Base ← 35----------------------------------------------45 → Acid(ALKALOSIS) (ACIDOSIS)

Please do these exercises. Identify whether the following values represent RESPIRATORY ACIDOSIS, RESPIRATORY ALKALOSIS, or NORMAL values.

1. pH 7.32pCO2 50 __________________________

2. pH 7.50pCO2 30 __________________________

3. pH 7.37pCO2 41 __________________________

Step IV. Look at the HCO3 (Bicarbonate)

HCO3 high (above 26) METABOLIC ACIDOSIS HCO3 low (below 22) METABOLIC ALKALOSIS

MIDDLE RANGE24

Acid ← 22 --------------------------------------- 26 → Base(ACIDOSIS) (ALKALOSIS)

Please do these exercises. Identify whether the following values represent METABOLIC ACIDOSIS, METABOLIC ALKALOSIS, or NORMAL values.

1. pH 7.28HCO3 18 ______________________

2. pH 7.52HCO3 32 ______________________

3. pH 7.43HCO3 25 ______________________

4. pH 7.30HCO3 20 ______________________

5. pH 7.48HCO3 28 ______________________

Step V. Determine the primary ACID – BASE disturbance

The change that matches the pH is the primary ACID – BASE DISTURBANCE.

1. pH and PaCO2 match: Respiratory Acid – Base Imbalance

a. pH ↓ ACIDOSIS RESPIRATORY ACIDOSISPaCO2 ↑ ACIDOSIS

b. pH ↑ ALKALOSIS RESPIRATORY ALKALOSIS PaCO2 ↑ ALKALOSIS

2. pH and HCO3 match: Metabolic Acid – Base Imbalance

a. pH ↑ ALKALOSIS METABOLIC ALKALOSISHCO3 ↑ ALKALOSIS

b. pH ↓ ACIDOSISHCO3 ↓ ACIDOSIS METABOLIC ACIDOSIS

Therefore: If pH are primarily affectedPCO2 (Same interpretation)

↓RESPIRATORY ACID – BASE IMBALANCE OCCURS

Therefore: If pH are primarily affectedHCO3 (Same interpretation)

↓METABOLIC ACID – BASE IMBALANCE OCCURS

Or better yet think about ROME!R – espiratoryO – ppositeM – etabolicE – qual

Check on these…1. Respiratory Acid – Base Imbalances

Respiratory Opposite means: the directions of pH and PaCO2 are opposite. Look at these examples.

pH ↓ RESPIRATORYPaCO2 ↑ ACIDOSIS

pH ↑ RESPIRATORYPaCO2 ↓ ALKALOSIS

2. Metabolic Acid – Base ImbalancesMetabolic Equal means: the directions of pH and HCO3 are EQUAL or SAME directions.

pH ↑ METABOLICHCO3 ↑ ALKALOSIS

pH ↓ RESPIRATORYHCO3 ↓ ACIDOSIS

Let’s put these in a nutshell…

Acid – Base Imbalances1. Respiratory

pH pCO2

Acidosis low high OppositeAlkalosis high low directions

2. MetabolicpH HCO3

Acidosis low low SameAlkalosis high high directions

Now, you’re ready to do the following exercises. Indicate in the following spaces provided whether the values represent ACIDOSIS, ALKALOSIS, or NORMAL.

1. pH 7.5 ________________________PaCO2 32 ________________________HCO3 26 ________________________

Please encircle your answer.Interpretation: RESPIRATORY ACIDOSIS

RESPIRATORY ALKALOSISMETABOLIC ACIDOSISMETABOLIC ALKALOSIS

2. pH 7.54 ________________________PaCO2 60 ________________________HCO3 32 ________________________

Please encircle your answer.Interpretation: RESPIRATORY ACIDOSIS

RESPIRATORY ALKALOSISMETABOLIC ACIDOSISMETABOLIC ALKALOSIS

3. pH 7.30 ________________________PaCO2 52 ________________________HCO3 30 ________________________

Please encircle your answer.Interpretation: RESPIRATORY ACIDOSIS

RESPIRATORY ALKALOSISMETABOLIC ACIDOSISMETABOLIC ALKALOSIS

4. pH 7.32 ________________________PaCO2 30 ________________________HCO3 18 ________________________

Please encircle your answer.Interpretation: RESPIRATORY ACIDOSIS

RESPIRATORY ALKALOSISMETABOLIC ACIDOSISMETABOLIC ALKALOSIS

How are you doing at this point? If you’re doing well, then proceed to the next step.

Step VI. Look at the degree of compensation. Check relationship between PaCO2 and HCO3

Remember: the lungs and kidneys normally attempt to help each other to maintain acid – base balance. If the lungs are unable to maintain acid – base balance, the kidneys will attempt to adjust levels of HCO3. If the kidneys are unable to maintain acid – base balance, the lungs will attempt to adjust levels of CO2. If CO2 and HCO3 levels move towards the same direction, i.e. both are high or both are low, then the acid – base imbalance are

COMPENSATED.

E.g.PaCO2 high (ACIDOSIS) HCO3 high (ALKALOSIS)

PaCO2 low (ALKALOSIS) HCO3 low (ACIDOSIS)

When is the acid – base imbalance considered as partial or complete compensation?

1. When the acid-base balance is compensated, but the pH is still ABNORMAL: PARTIAL COMPENSATION.2. When the acid-base is balance compensated, and the pH is NORMAL : COMPLETE COMPENSATION.

When is the acid – base imbalance considered uncompensated?

When the CO2 and HCO3 levels more towards opposite directions. (The problem is worsened.)

E.g.PaCO2 high (ACIDOSIS) HCO3 high (ALKALOSIS)

PaCO2 low (ALKALOSIS) HCO3 low (ACIDOSIS)

Or when PaCO2 is abnormal and HCO3 remains normal and vise versa, the acid-base imbalance is also uncompensated

In capsule: to do the AGB analysis, do the following steps:I. Recall the normal values.II. Look at the pH.III. Look at the PaCO2.IV. Look at the HCO3.V. Determine the primary acid-base imbalance.VI. Determine whether the acid-base imbalance is compensated or uncompensated.VII. If the acid-base imbalance is compensated, determine whether it is partial compensation or complete compensation.

You are now ready to apply your knowledge

Please do the following exercises.

Remember, retention of the knowledge is 90% when you say it and you do it.

ACID – BASE IMBALANCE INTERPRETATION EXERCISES.

Place a check (√) in the appropriate column indicating whether the pH is Normal, ACIDOTIC, or ALKALOTIC.pH Normal Acidosis Alkalosis

1. 7.372. 7.613. 7.194. 7.505. 7.306. 7.417. 7.488. 7.289. 7.3510. 7.52

Check (√) whether the following data represent RESPIRATORY ACIDOSIS, RESPIRATORY ALKALOSIS or NORMALpH PaCO2 Respiratory Acidosis Respiratory Alkalosis Normal

11. 7.2012. 7.5213. 7.3314. 7.4815. 7.38

Check (√) whether the following data represent METABOLIC ACIDOSIS, METABOLIC ALKALOSIS or NORMALpH HCO3 BE Metabolic Acidosis Metabolic Alkalosis Normal

16. 7.26 19 -617. 7.42 24 018. 7.42 15 -819. 7.54 35 +620. 7.51 30 +4

Identify the primary acid – base disturbance if any, and indicate whether compensation is partial or complete or uncompensated acid – base imbalance.21. pH 7.5

PaCO2 31HCO3 26 ________________________________________________

22. pH 7.38PaCO2 32HCO3 19 ________________________________________________

23. pH 7.24PaCO2 60HCO3 32 ________________________________________________

24. pH 7.41PaCO2 30HCO3 18 ________________________________________________

25. pH 7.5PaCO2 42HCO3 33 ________________________________________________

Congratulations!You have learned a crucial knowledge towards excellence in CARE!