ABG, Oximetry, Spirometry Testing

Question 1

What info do you get from ABG?

Answer 1

Acid base status

Oxygenation (dissolved O2, saturation of Hb)

CO2 elimination –> ventilation

Levels of carboxyhemoglobin/methemoglobin

Question 2

What are the indications for ABG testing?

Answer 2

Asses ventilatory status (aka CO2 elimination)

oxygenation

acid-base status

Assess response to intervention

Question 3

What are the contraindications for ABG testing?

Answer 3

Bleeding diathesis

AV fistula

Severe peripheral vascular dz

No arterial pulse

Infection over site

Question 4

What is better about pulse ox compared to ABG?

Answer 4

Non-invasive

Continuous data

Question 5

What are drawbacks about pulse ox compared to ABG?

Answer 5

No VENTILATION (pCO2)!!

No acid-base status

Unreliable when pO2 < 70-80%

Can get errors

No methemoglobin/carboxyhemoglobin

Question 6

Which artery is best for ABG and why?

Answer 6

Radial (can use femoral, dorsal is pedis, brachial in emergency)

Superficial

Has collaterals

Easily compressible

Question 7

What are the normal ABG values (pH, PaO2, PaCO2, HCO3)?

Answer 7

pH = 7.35 - 7.45

PaO2 = 80 - 100

PaCO2 = 35 -45 mmHg

HCO3 = 22 - 26 mEq/L

Question 8

What are acidotic ABG values (pH, PaO2, PaCO2, HCO3)?

Answer 8

pH = < 7.35

PaO2 = N/A

PaCO2 = > 45 mmHg

HCO3 = < 22 mEq/L

Question 9

What are alkalotic ABG values (pH, PaO2, PaCO2, HCO3)?

Answer 9

pH = > 7.45

PaO2 = N/A

PaCO2 = < 35 mmHg

HCO3 = > 26 mEq/L

Question 10

When interpreting ABG, when would you decide someone has respiratory acidosis?

Answer 10

Low pH

High pCO2

Question 11

When interpreting ABG, when would you decide someone has metabolic acidosis?

Answer 11

Low pH

Low HCO3

Question 12

When interpreting ABG, when would you decide someone has respiratory alkalosis?

Answer 12

High pH

Low pCO2

Question 13

When interpreting ABG, when would you decide someone has metabolic alkalosis?

Answer 13

High pH

High HCO3

Question 14

What happens in respiratory alkalosis?

Answer 14

For every 10 decrease in pCO2 –> HCO3 decreases by 2/increase in pH of 0.08

Question 15

What are the central causes of respiratory alkalosis?

Answer 15

Respiratory center issues

Ischemia

CNS tumor

Hyperventilation

Question 16

What are the lung issues that cause respiratory alkalosis?

Answer 16

Pneumonia

Asthma

PE

Question 17

What are the chest cavity issues that can caues respiratory acidosis?

Answer 17

Flail Chest

Pneumothorax

Effusion

Question 18

What are the central causes of respiratory acidosis?

Answer 18

Sedation

CVA

Narcotics

Neuromuscular issues

Question 19

What are some lung issues that can cause respiratory acidosis?

Answer 19

Pneumonia

Asthma

FB

COPD

Question 20

What is spirometry used for?

Answer 20

Diagnosing Asthma/COPD

Question 21

What are the most important indications to use spirometry?

Answer 21

Persistant cough

Chronic sputum production

Breathlessness on exertion

Reduction in activity

Question 22

What are some other indications for spirometry testing?

Answer 22

Recurrent/chronic respiratory symptoms

Occupational exposure to respiratory irritants

Family Hx of respiratory dz/symptoms –> alpha1-antitrypsin; early onset emphysema

REQUIRED quality measure for accurate COPD diagnosis

Selective screening in high risk populations (fam. medicine)

Question 23

What types of diseases can spirometry differentiate?

Answer 23

Restrictive vs Obstructive

Question 24

Is Spirometry recommended for screening of COPD pts?

Answer 24

NOT routine screening tool

Only recommended in PRESENCE of respiratory symptoms

Question 25

Why is QUALITY spirometry important?

Answer 25

Prevent overdiagnosis of COPD

Question 26

According to the NAEPP (National Asthma Education & Prevention Program) when should you use spirometry?

Answer 26

For initial diagnosis (can't diagnosis w/o spirometry testing!) After treatment is initiated/symptoms and peak flow have stabilized During periods of loss of asthma control Assessing response change to pharmacotherapy Every 1 - 2 years to assess maintenance of airway function Check PEF meter accuracy

Question 27

What is the FEV1 or FEV1/FVC of a asthmatic 5 - 11 yo that is considered well controlled?

Answer 27

FEV1 = \> 80% predicted FEV1/FVC = \> 80%

Question 28

What is the FEV1 or FEV1/FVC of an asthmatic 5 - 11 yo that is considered not well controlled?

Answer 28

FEV1 = 60 - 80% predicted FEV1/FVC = 75 - 80%

Question 29

What is the FEV1 or FEV1/FVC of an asthmatic 5 - 11 yo that is considered very poorly controlled?

Answer 29

FEV1 = \< 60% predicted FEV1/FVC = \< 75%

Question 30

What do you have to do before you do spirometry?

Answer 30

Coach patient (so get max effort --\> accuracy)

Question 31

What is the most important varible for spirometry?

Answer 31

Pace of expired air --\> should be released w/ explosive force)

Question 32

What is the minimum exhalation interval?

Answer 32

6 seconds w/ 2 second plateau

Question 33

How should the patients be positioned during spirometry?

Answer 33

Sitting or Standing

Question 34

What are the contraindications for spirometry (edit this, there's a lot)?

Answer 34

\> 6 wks since last exacerbation MI \< 3 -6 months ago Unstable agina in last 24 hrs Haemoptysis of unknown origin Recent Eye, abdominal Surgery (\< 3 - 6 months ago) CVA \< 3 -6 months ago Pt w/ TB PE \< 3 -6 months ago Ear infection Sponatneous pneumothorax Aortic Aneurysm

Question 35

What are some of the common reasons for unacceptable/unreliable readings?

Answer 35

Inadequate or incomplete inhalation Lack of blast effor during exhalation --\> false (+) COPD Additional breath during maneuver Lips not tight around mouthpiece Slow start to forced exhalation Exhalation stops before complete expiration Exhalation through nose Coughing Tight/Restrictive clothing

Question 36

What should you avoid during spirometry?

Answer 36

Unsatisfactory start (excessive hesitation/false start) Air leak Coughing during first second Early termination of forced expiration Glottis closure Obstructed mouthpiece (Tongue/false teeth/Chewing gum)

Question 37

What is FEV1?

Answer 37

Forced expired volume in 1 second

Question 38

What is FVC and what can be substituted for this value?

Answer 38

Forced Vital Capacity FEV6 can substitute it

Question 39

What is PEFR?

Answer 39

Peak expiratory flow rate (not reproducible, but useful in tracking progress)

Question 40

What is FEF 25 - 75%?

Answer 40

Forced expiratory flow between 25 - 75% of the vital capacity (Usually not clinically useful)

Question 41

What are some factors that would affect normal spirometry values?

Answer 41

Height --\> Tall = larger lungs Age --\> Function declines w/ age Sex --\> females have smaller volumes Race --\> Blacks/Asians had smaller lung volumes Posture --\> reduced in supine position

Question 42

Why is it important to enter accurate values for pt's bio-demographic variables?

Answer 42

Prevent misdiagnosis