Final Lecture: Mountain Dew, Capnography, Ventilation (Final Exam)

Question 1

Would releasing of a tourniquet increase or decrease EtCO₂ ?
Why?

Answer 1

• ↑ EtCO₂
• Tourniquet’s trap metabolic byproducts (H⁺, CO₂, etc.) that continue to be produced. When released, these byproducts flood systemic circulation.

Question 2

Would fever increase or decrease EtCO₂ ?
Why?

Answer 2

• ↑ EtCO₂
• Fever = increased metabolic rate

Question 3

Would decreased cardiac output increase or decrease EtCO₂ ?
Why?

Answer 3

• ↓ EtCO₂ (ex. intraoperative MI)
• Less CO₂ exchange can occur in the lungs due to less blood movement

Question 4

Would a pulmonary embolism increase or decrease EtCO₂?

Answer 4

↓ EtCO₂

Question 5

Would increased blood pressure increase or decrease EtCO₂?

Answer 5

↑ EtCO₂

Question 6

Would hypo or hyper-ventilation result in a decreased EtCO₂?

Answer 6

• Hyperventilation = ↓ EtCO₂
• more CO₂ being “blown” off

Question 7

Would esophageal intubation result in a decreased or increased EtCO₂?

Answer 7

↓ EtCO₂

Question 8

Would abdominal insufflation result in an increased or decreased EtCO₂?

Answer 8

↑ EtCO₂

Question 9

What is often the first sign of malignant hyperthermia?

Answer 9

↑ EtCO₂

Question 10

Would an airway obstruction or a circuit disconnection result in a decreased EtCO₂?

Answer 10

Trick question. Both will result in a ↓ EtCO₂

Question 11

Would a HCO₃⁻ infusion result in an increase or decrease to EtCO₂?
Why?

Answer 11

• ↑CO₂
• H⁺ + HCO₃⁻ ⇔ CO₂ + H₂O (equation pushed to the right, ↑CO₂ produced)

Question 12

What change would occur with EtCO₂ due to dead space development?
Why?

Answer 12

• ↓ EtCO₂
• Air trapping ala COPD = increased CO₂ trapping and less CO₂ available to escape

Question 13

What would occur with our capnographic waveform with hypoventilation?

Answer 13

EtCO₂ waveform would become elevated

Question 14

What would occur with our capnographic waveform with hyperventilation?

Answer 14

EtCO₂ waveform would become stunted

Question 15

What would you surmise to be the cause of the EtCO₂ waveform below?

Answer 15

Falling CO (v bad)

Question 16

What would you surmise to be the cause of the EtCO₂ waveform below?

Answer 16

Increasing CO (ex. successful CPR)

Question 17

What appearance would an EtCO₂ waveform take with bronchospasm?
Why?

Answer 17

“Shark-fin” upsloping appearance due to difficulty emptying small airways of the lungs

Question 18

What could be cause of the EtCO₂ waveform below?

Answer 18

Esophageal intubation, self-extubation, disconnection…. death.

Question 19

Based on the figure below, when would you expect expiration to start?
How about for expiration to end?

Answer 19

• Expiration start: Somewhere in between A and B
• Expiration end: E

Question 20

What is normal FRC for a standing patient?

Answer 20

3L

Question 21

What might FRC be for someone in the supine position, awake and spontaneously breathing?

Answer 21

FRC = 2 - 2.5 L

Question 22

How might FRC change for a sedated patient in an assisted mode of ventilation?

Answer 22

FRC = 1.75L

Question 23

How might FRC change for a supine patient who is paralyzed and completely ventilated?

Answer 23

FRC = 1L (maybe even as low as 0.75L)

Question 24

What occurs with air when at RV in a supine, paralyzed patient?

Answer 24

Air goes anteriorly, away from the more perfused areas of the lung.

Question 25

How can we treat poor V/Q ratios for the supine, paralyzed patient?

Answer 25

• ↑PEEP to ↑FRC
• ↑ FiO₂