arterial blodd gas analysis

7/30/2019 Arterial Blodd Gas Analysis

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by: MARITES A. ROSAPAPAN, RN,MANc



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Acid Base Balance Acid

- substance that can donate or release hydrogen

ionsie Carbonic acid, Hydrochloric acid

** Carbon dioxide – combines with water to form

carbonic acid

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Base- substance that can accept hydrogen ions

Ie Bicarbonate

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BUFFER - substance that canaccept or donate hydrogen- prevent excessive changes in pH

TYPES OF BUFFER

1. Bicarbonate (HCO3): carbonic acid buffer(H2CO3)

2. Phosphate buffer

3. Hemoglobin buffer

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Dynamics of Acid Base Balance Acids and bases are constantly produced in

the body

They must be constantly regulated

CO2 and HCO3 are crucial in the balance

A HCO3:H2CO3 ratio of 20:1 should bemaintained

Respiratory and renal system are active inregulation

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Kidney- Regulate bicarbonate level in ECF

1. RESPIRATORY/METABOLIC ACIDOSIS- kidney excrete H and reabsorbs/generatesBicarbonate

2. RESPIRATORY/METABOLIC ALKALOSIS

- kidney retains H ion and excrete Bicarbonate

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Lung- Control CO2 and Carbonic acid content of ECF

1. METABOLIC ACIDOSIS- increased RR to eliminate CO2

2. METABOLIC ALKALOSIS- decreased RR to retain CO2

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pH - measures degree of acidity andalkalinity - indicator of H ion concentration

- Normal ph 7.35-7.45

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ACIDOSIS

- decreased pH; < 7.35

- increased Hydrogen

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ALKALOSIS - increased pH-; > 7.45- decreased Hydrogen

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ACUTE AND CHRONIC

METABOLIC ACIDOSIS- Low pH

- Increased H ion concentration

- Low plasma BicarbonateEtiology: diarrhea, fistulas, diuretics, renal insufficiency,TPN w/o Bicarbonate, ketoacidosis, lactic acidosis

S/sx: headache, confusion, drowsiness, inc RR, dec BP,cold clammy skin, dysrrythmia, shock

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Dx: ABG – low Bicarbonate, low pH, Hyperkalemia,

ECG changes

Rx: Bicarbonate for pH < 7.1 and Bicarbonate level < 10monitor serum K

dialysis

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ACUTE AND CHRONIC

METABOLIC ALKALOSIS

High pH

Decreased H ion concentration

High plasma Bicarbonate

Etiology: vomiting, diuretic, hyperaldosteronism,

hypokalemia, excesive alkali ingestion

s/sx: tingling of toes, dizziness, dec RR, inc PR, ventricular disturbances

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Dx:ABG – pH > 7.45, serum Bicarbonate > 26 mEq/L,inc PaCO2

Rx: restore normal fluid balancecorrect hypokalemia

Carbonic anhydrase inhibitors

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ACUTE AND CHRONIC

RESPIRATORY ACIDOSIS Ph < 7.35

PaCO2 > 42 mmHg

Etiology: pulmonary edema, aspiration, atelectasis,pneumothorax, overdose of sedatives, sleep apneasyndrome, pneumonia

s/sx: sudden hypercapnia produces inc PR, RR, incBP, mental cloudinesss, feeling of fullness in head,papil edema and dilated conjunctival blood vessels

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Dx: ABG – pH < 7.35

PaCO2 - > 42 mmHg

Rx: improve ventilation

pulmonary hygiene

mechanical ventilation

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ACUTE AND CHRONIC

RESPIRATORY ALKALOSIS

pH > 7.45

PaCO2 < 38 mmHg

Etiology: extreme anxiety, hypoxemia

s/sx: light headednes, inability to concentrate,numbness, tingling, loss of consciousness

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Dx: ABG – pH > 7.45

PaCO2 < 35dec K

dec Ca

Rx: breathe slowly

sedative

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ARTERIAL BLOOD GAS ANALYSISParameter Normal Value

pH 7.35 – 7.45

PaCO2 35 – 45 mmHg

HCO3 22-26mEq/L

O2 saturation 95 - 100%

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How to Obtain blood sample? Allen’s test - evaluate patency of

radial and ulnar artery

Heparinized syringe andcontainer

Pressure dressing, no activity atthe site and check 5 p’s distal tothe site of punctured artery

Note if patient is under O2therapy

Label the sample and sendimmediately to the laboratory

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ABG Responsibilities Arterial blood

Radial or ulnar artery

Allen’s test

Prepare

Heparinized (Syringe, specimen container)

Note: 02 therapy, FIO2, temp (bmr, o2)

Bring specimen to the LAB (ice)

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After injection

Maintain extension position, no activity 8H

Apply pressure 5-15 min Observe the site

Distal, 5 p’s

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Vascular assess

Pulselessness

Pain Paresthesia

Poikilothermia

Pallor

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Handling of Specimen Expel all air bubbles immediately

Do not agitate the syringe

Discard frothy specimen

1:1000 U/ml HEPARIN

Place sample in ice

Cool sample to 5 C if it can not be analyzed quickly

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Evaluating ABG’s 1. Note the pHpH = 7.35 – 7.45 (normal)pH = < 7.35 (acidosis)pH = > 7.45 (alkalosis)

Partially compensated – if the Co2 and Hco3are the same, with abnormal pH

Fully Compensated – if the pH is normal Uncompensated – if the Co2 and HCo3 are opposite,

with or if one of them is normal, abnormal pH

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2. Determine primary cause of disturbance2.1 pH > 7.45

a. PaCo2 < 40 mmHg – respiratory alkalosisb. HCO3 > 26 mEq/L – metabolic alkalosis

2.2 pH < 7.35

a. PaCo2 > 40 mmHg – respiratory acidosisb. HCO3 < 26 mEq/L – metabolic acidosis

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3. Determine compensation by looking at the valueother than the primary disturbance

pH PaCO2 HCO3

7.20 60mmHg

24mEq/L

7.30 60

mmHg

37

mEq/l

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UncompensatedRespiratory acidosis

Partially CompensatedRespiratory acidosis



4. Mixed acid-basedisorders

pH 7.21 Dec acid

PaCO2 52 Inc acid

HCO3 13 Dec acid

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MetabolicandRespiratory

Acidosis



DRILL pH = 7.40

HCO3 = 20

PaCO2 = 40

Simple Metabolic Acidosis

pH = 7.40

HCO3 = 28

PaCO2 = 40

Simple Metabolic Alkalosis

pH = 7.40

HCO3 = 24

PaCO2 = 48

Simple Respiratory Acidosis

pH = 7.40

HCO3 = 24

PaCO2 = 32

Simple Respiratory Alkalosis

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pH = 7.33

HCO3 = 20

PaCO2 = 40

pH = 7.47

HCO3 = 28 PaCO2 = 40

pH = 7.33

HCO3 = 24

PaCO2 = 48

pH = 7.47

HCO3 = 24 PaCO2 = 32

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DRILL

pH = 7.33

HCO3 = 20

PaCO2 = 32

pH = 7.47

HCO3 = 28

PaCO2 = 48

pH = 7.33

HCO3 = 28

PaCO2 = 48

pH = 7.47

HCO3 = 20

PaCO2 = 32

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ANSWER:

pH = 7.33

HCO3 = 20

PaCO2 = 32

Uncompensated Metabolic Acidosis

pH = 7.47

HCO3 = 28

PaCO2 = 48

Uncompensated Metabolic Alkalosis

pH = 7.33

HCO3 = 28

PaCO2 = 48

Uncompensated Respiratory Acidosis

pH = 7.47

HCO3 = 20

PaCO2 = 32

Uncompensated Respiratory Alkalosis

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DRILL

pH = 7.40

HCO3 = 18

PaCO2 = 32

pH = 7.35

HCO3 = 30

PaCO2 = 48

pH = 7.40

HCO3 = 28

PaCO2 = 48

pH = 7.44

HCO3 = 20

PaCO2 = 32

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ANSWER

pH = 7.40 HCO3 = 18 PaCO2 = 32 Fully

Compensated Metabolic Acidosis

pH = 7.35 HCO3 = 30 PaCO2 = 48 Partially Compensated Respiratory

Acidosis

pH = 7.40 HCO3 = 28 PaCO2 = 48 Fully

Compensated Respiratory Acidosis

pH = 7.44 HCO3 = 20

PaCO2 = 32 Partially Compensated Respiratory

Alkalosis

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Thank You!

arterial blodd gas analysis

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