Capnography

Question 1

Capnography

Answer 1

Gold standard in endotracheal tube intubation and confirmation

Question 2

AHA Class 1 for cardiac arrest patients

Answer 2

there is no risk and all benefit

Question 3

Phase 1

Answer 3

The respiratory baseline. it is flat when no CO2 is present and corresponds to the late phase of inspiration and early part of expiration

Question 4

Phase 2

Answer 4

The respiratory upstroke. This represent exhalation of a mixture of dead-space gases and alveolar gases from alveoli with the shortest transport time

Question 5

Phase 3

Answer 5

The respiratory plateau. It reflects the airflow through uniformly ventilated alveoli with a nearly constant CO2 level. The highest level of the plateau is called the “ETCO2” and is recorded as such by the capnometer

Question 6

Phase 4

Answer 6

The inspiratory phase. It is a sudden down stroke and ultimately returns to the baseline during inspiration. The respiratory pause restarts the cycle

Question 7

Normal

Answer 7

Square Box waveform

ETCO2 = 35-45mmHg

Question 8

Dislodged Endotracheal Tube (ETT)

Answer 8

Loss of waveform

Loss of ETCO2 reading

Management: Replace ETT

Question 9

Esophageal intubation (or apnea)

Answer 9

Absence of waveform

Absence of ETCO2 reading

Management: Ventilate or intubate

Question 10

CPR

Answer 10

Square box waveform

ETCO2 = 10 - 15mmhg

Management: Change rescuers if ETCO2 falls below 10mmhg

Question 11

Obstructive airway

Answer 11

“Shark fin” waveform

With or without prolonged expiratory phase can be seen before actual “attack” or “exacerbation”

Bronchospam -> asthma, COPD, anaphylaxis, FBAO

Management: Bronchodilators & treat underlying cause (albuterol, atrovent, racemic epinephrine, epinephrine)

Question 12

ROSC

Answer 12

During CPR, sudden increase of ETCO2 above 10-15mmhg

Management: Check femoral or carotid pulse

Question 13

Rising Baseline

Answer 13

Patient is rebreathing CO2

Management: Check equipment for adequate oxygen flow, allow more time for exhalation, ensure cuff has good seal

Question 14

Hypoventilation

Answer 14

Prolonged waveform
ETCO2 > 45mmhg

Management: Assist ventilations, increase respiratory/ ventilatory rate

Question 15

Hyperventilation

Answer 15

Shortened waveform
ETCO2 < 35mmHg

Management: Slow respirations/ventilatory rate

Consider other causes: DKA, sepsis, TCA overdose, methanol ingestion

Question 16

Breathing around ETT

Answer 16

Angled, sloping down stroke on waveform

Ruptured cuff or ETT too small

Management: Check cuff and tube size, possible re-intubation

Question 17

Curare Cleft

Answer 17

Neuromuscular blockade is wearing off

Patient takes small breath that causes the cleft

Management: Consider re-administration of neuromuscular blockade medication