What should you do if ETCO2 is less than 35 mmHg (hyperventilation)?

What should you do if ETCO2 is less than 35 mmHg (hyperventilation)?

• A. Lower oxygen flow
• B. Bolus injectable
• C. Check equipment & Check temp
• D. ↑ FGF and/or ↑ Inhalant

Answer: (D)

ETCO2 reflects how well CO2 is being eliminated by the lungs and alveolar ventilation. When ETCO2 is below 35, the patient is hyperventilating and blowing off CO2 faster than it is produced. The goal is to raise ETCO2 back toward the normal range by reducing CO2 elimination or by increasing inspired CO2, i.e., adjust ventilation to decrease minute ventilation (lower rate or smaller breaths) or, if possible, increase the CO2 delivered in the inspired gas. Before making ventilatory changes, it’s prudent to verify the reading isn’t an artifact by checking the equipment, including the sampling line, circuit integrity, and temperature calibration. Lower oxygen flow won’t address the CO2 level, and giving a bolus of medication doesn’t affect end-tidal CO2. Increasing fresh gas flow or raising the inhaled anesthetic concentration, in most circle systems, would tend to reduce CO2 retention (and further lower ETCO2), not correct hypocapnia, so they’re not the appropriate steps for rising ETCO2.

ETCO2 reflects how well CO2 is being eliminated by the lungs and alveolar ventilation. When ETCO2 is below 35, the patient is hyperventilating and blowing off CO2 faster than it is produced. The goal is to raise ETCO2 back toward the normal range by reducing CO2 elimination or by increasing inspired CO2, i.e., adjust ventilation to decrease minute ventilation (lower rate or smaller breaths) or, if possible, increase the CO2 delivered in the inspired gas. Before making ventilatory changes, it’s prudent to verify the reading isn’t an artifact by checking the equipment, including the sampling line, circuit integrity, and temperature calibration.

Lower oxygen flow won’t address the CO2 level, and giving a bolus of medication doesn’t affect end-tidal CO2. Increasing fresh gas flow or raising the inhaled anesthetic concentration, in most circle systems, would tend to reduce CO2 retention (and further lower ETCO2), not correct hypocapnia, so they’re not the appropriate steps for rising ETCO2.