An asthmatic patient on volume-controlled ventilation develops rising plateau and end-tidal CO2 values with audible prolonged expiration. Dynamic hyperinflation with auto-PEEP is suspected. Which ventilator change is most appropriate?

• A Increase respiratory rate to improve CO2 clearance
• B Shorten the expiratory time by increasing inspiratory flow fraction
• C Increase tidal volume to recruit collapsed alveoli
• D Decrease inspiratory time and reduce respiratory rate to prolong expiratory time ✓

Explanation

Auto-PEEP arises when exhalation is incomplete before the next breath, trapping gas and raising intrathoracic pressure. The treatment is to lengthen expiratory time: lower the respiratory rate, decrease inspiratory time (raise inspiratory flow or lower I:E ratio toward 1:3 or 1:4) and reduce tidal volume if needed. Increasing rate or shortening expiration worsens gas trapping and can precipitate haemodynamic collapse from elevated intrathoracic pressure reducing venous return.

Reference: Morgan and Mikhail's Clinical Anesthesiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.