Quizzes – Society of Mechanical Ventilation

Volumetric Capnography

Volumetric Capnometry

1 / 5

1) Adult female patient, hospitalized comatose after car accident with no visible injuries, presents after intubation with low blood pressure, hyperglycemia, and a heart rate of 118 beats/min (tachycardia).
What does the volumetric capnogram indicate?

(Credit Hamilton Medical)

Pneumothorax

ARDS

Hemorrhagic shock

Airway Obstruction

ARDS and Pneumothorax will have increased dead space. The dead space is normal in the figure, the reduced PeCO2 is secondary to shock with reduced CO2 production

2 / 5

2) 89 year old male weighting 70 Kg admitted for septic shock and intubated. His V‘CO2 (Volume of CO2 eliminated/minute) is 70 ml/min/kg

The V'CO2 is:

Normal

High

Low

Normal VCO2 is about 2.6 to 2.9 ml/min/kg so the normal expected should be between 180-200

Causes: Hypothermia, deep sedation, hypothyroidism, paralysis, decrease CO2 production, decreased cardiac output or blood loss

3 / 5

3) The blue shaded area Y in the capnogram above represent ?

Total dead space

Anatomical dead space

Alveolar dead space

Inspiratory resistance equal: Peak Insp Pressure (PIP) - Plateau Pressure (Pplat) / Inspiratory flow (L/second)

40 - 10 / 1 = 30 cmH2O/L/sec

4 / 5

4) A 65-year-old male, with ideal body weight of 60 kg intubated for traumatic brain injury and coma. His tidal volume is 450 ml. His Alveolar tidal volume is 260 ml. The dead space is:

Normal

High

Low

Total dead space will be equal Tidal volume - alveolar tidal volume = 190 ml

Dead space / Tidal volume: 190 / 450 = 42%

Normal Anatomical dead space: 2.2 ml/kg

Normal Dead space / Tidal volume about 25-30%

5 / 5

5) A patient is intubated for ARDS, because of hypotension PEEP was reduced from 15 cmh2o to 10. SpO2 remains the same, VCO2 and Alveolar tidal volume drop. This indicate ?

Initial PEEP was too high

Worsening hemodynamics by the reduced PEEP

De-recruitment by the reduced PEEP

The reduction in both VCO2 and Alveolar tidal volume indicating worsening alveolar dead space is secondary to de-recruitment of the alveoli after PEEP reduction

Your score is

The average score is 50%

Exit

The Golden Ticket Quiz

The Golden Ticket Quiz

Win a free Virtual attendance to our upcoming conference June 30 - July 1

One 100% correct answer winner every 10 days

If you want to be included in the raffle and ok to share your name as a winner in the social media, please enter your name and e-mail, if not please leave empty

2nd SMV Conference 2025

1 / 5

(Credit Hamilton Medical)

Pneumothorax

ARDS

Hemorrhagic shock

Airway Obstruction

ARDS and Pneumothorax will have increased dead space. The dead space is normal in the figure, the reduced PeCO2 is secondary to shock with reduced CO2 production

2 / 5

2) 89 year old male weighting 70 Kg admitted for septic shock and intubated. His V‘CO2 (Volume of CO2 eliminated/minute) is 70 ml/min/kg

The V'CO2 is:

Normal

High

Low

Normal VCO2 is about 2.6 to 2.9 ml/min/kg so the normal expected should be between 180-200

Causes: Hypothermia, deep sedation, hypothyroidism, paralysis, decrease CO2 production, decreased cardiac output or blood loss

3 / 5

3) The blue shaded area Y in the capnogram above represent ?

Total dead space

Anatomical dead space

Alveolar dead space

Inspiratory resistance equal: Peak Insp Pressure (PIP) - Plateau Pressure (Pplat) / Inspiratory flow (L/second)

40 - 10 / 1 = 30 cmH2O/L/sec

4 / 5

4) A 65-year-old male, with ideal body weight of 60 kg intubated for traumatic brain injury and coma. His tidal volume is 450 ml. His Alveolar tidal volume is 260 ml. The dead space is:

Normal

High

Low

Total dead space will be equal Tidal volume - alveolar tidal volume = 190 ml

Dead space / Tidal volume: 190 / 450 = 42%

Normal Anatomical dead space: 2.2 ml/kg

Normal Dead space / Tidal volume about 25-30%

5 / 5

5) A patient is intubated for ARDS, because of hypotension PEEP was reduced from 15 cmh2o to 10. SpO2 remains the same, VCO2 and Alveolar tidal volume drop. This indicate ?

Initial PEEP was too high

Worsening hemodynamics by the reduced PEEP

De-recruitment by the reduced PEEP

The reduction in both VCO2 and Alveolar tidal volume indicating worsening alveolar dead space is secondary to de-recruitment of the alveoli after PEEP reduction

Your score is

The average score is 80%

Exit

Ventilator Waveforms

Ventilator Waveforms

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Where would you set the PEEP according to that semi-quasistatic P-V curve ?

The low inflection point or the airway closure point (red triangle) is about 11, also the maximum hysteresis (difference in volume between the inspiratory and expiratory tidal volume)

Hysteresis

2 / 5

Which image has a Stress Index > 1 indicating the need to reduce PEEP?