A ventilator is set at a rate of 15 breaths per minute with an I:E ratio of 1:2. What is the inspiratory time?
- A 1.0 seconds
- B 1.33 seconds ✓
- C 2.0 seconds
- D 2.67 seconds
Correct answer: B. 1.33 seconds
Explanation
At 15 breaths per minute, one total respiratory cycle lasts 60 divided by 15, which equals 4 seconds. With an I:E ratio of 1:2, the cycle divides into three equal parts, giving an inspiratory time of 4 divided by 3, approximately 1.33 seconds, and an expiratory time of about 2.67 seconds. Choosing 2.67 seconds confuses inspiration with expiration, and 2.0 seconds results from incorrectly halving the cycle length rather than dividing into three parts.
Reference: Morgan and Mikhail's Clinical Anesthesiology, 5th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.