BCIA Breathing & Capnometry Biofeedback 1 — Questions and Answers
Question 1: What does end-tidal CO2 (EtCO2) measure in capnometry biofeedback?
- Oxygen saturation at the end of inhalation
- Carbon dioxide concentration at the end of exhalation (Correct answer)
- Nitrogen levels during normal respiration
- Blood pressure changes during breathing
Correct answer: Carbon dioxide concentration at the end of exhalation
End-tidal CO2 measures the concentration of carbon dioxide at the end of a complete exhalation, closely approximating alveolar and arterial CO2 levels.
Question 2: What is the normal range for end-tidal CO2 (EtCO2) in healthy resting adults?
- 15–25 mmHg
- 35–45 mmHg (Correct answer)
- 50–60 mmHg
- 60–75 mmHg
Correct answer: 35–45 mmHg
Normal EtCO2 in healthy resting adults ranges from 35–45 mmHg, reflecting adequate alveolar ventilation matched to metabolic demand.
Question 3: What term describes chronically low CO2 levels caused by over-breathing?
- Hypercapnia
- Hyperoxia
- Hypocapnia (Correct answer)
- Hypoxemia
Correct answer: Hypocapnia
Hypocapnia refers to abnormally low arterial CO2, which occurs when breathing rate and depth exceed metabolic CO2 production, as in hyperventilation.
Question 4: At approximately what breathing rate does resonance frequency breathing typically occur to maximize HRV?
- 2–4 breaths per minute
- 6 breaths per minute (Correct answer)
- 12–15 breaths per minute
- 18–20 breaths per minute
Correct answer: 6 breaths per minute
Resonance frequency breathing occurs near 6 breaths per minute (~0.1 Hz), which entrains the baroreflex and maximizes heart rate variability oscillations.
Question 5: Which breathing pattern is emphasized in biofeedback training to maximize ventilation efficiency and reduce muscle tension?
- Chest/thoracic breathing
- Paradoxical breathing
- Apneustic breathing
- Diaphragmatic breathing (Correct answer)
Correct answer: Diaphragmatic breathing
Diaphragmatic breathing engages the primary respiratory muscle and is more efficient than thoracic breathing, improving gas exchange and reducing accessory muscle tension.
Question 6: What is the Bohr effect, as relevant to breathing biofeedback?
- Increased oxygen release from hemoglobin as CO2 rises (Correct answer)
- Decreased heart rate during exhalation
- Increased oxygen uptake during hyperventilation
- Reduced respiratory rate during acute stress
Correct answer: Increased oxygen release from hemoglobin as CO2 rises
The Bohr effect describes how elevated CO2 and lower pH cause hemoglobin to release more oxygen to tissues; hyperventilation lowers CO2, paradoxically reducing tissue oxygenation.
Question 7: Which symptom is most commonly associated with acute hyperventilation syndrome?
- Hyperthermia and profuse sweating
- Tingling in the extremities and lightheadedness (Correct answer)
- Bradycardia and hypertension
- Increased appetite and weight gain
Correct answer: Tingling in the extremities and lightheadedness
Acute hyperventilation causes hypocapnia leading to cerebral vasoconstriction and respiratory alkalosis, which produces peripheral tingling (paresthesia) and lightheadedness.
BCIA Breathing & Capnometry Biofeedback 1
What does end-tidal CO2 (EtCO2) measure in capnometry biofeedback?