62 years old female who was intubated for acute on chronic hypercapnic respiratory failure secondary to COPD exacerbation. Her ideal body weight is 67 Kg. CXR shows severely hyperinflated lungs.
Patient was placed on AC mode of ventilation with VT of 450 mL, RR of 22 per minute, and an inspiratory flow of 60 L/min. Her minute ventilation was 10 liters per minute.
Blood gases revealed acute on chronic respiratory acidosis with pH of 7.22 and pCO2 of 75
An inspiratory hold maneuver was done and shown in the following screenshot:
In addition, an expiratory hold maneuver was done revealing the following:
Patient is sedated with propofol and fentanyl but not yet paralyzed. What would you do next?
What changes would you make on the ventilator settings (may select multiple)?
0%Increase inspiratory flow rate
0%Decrease respiratory rate
0%Decrease tidal volume
0%Increase PEEP
You can vote for more than one answer.
I guess all the answers are right, the goal is to prolong the expiratory time to allow for complete exhalation of the air. I would start by increasing the flow rate trying to decrease the inspiratory time and I:E ratio without changing the minute ventilation. Then I would decrease the tidal volume and/or the rate and accepting permissive hypercapnea. Adding external PERP can help triggering on the ventilator as this would allow the patient to exert less efforts.
This screenshot shows an increased flow rate to 70 L/min, decreased rate to 14, and decreased tidal volume to 450:
inspiratory hold now shows improved plateau pressure to 22:
And expiratory hold shows improved autoPEEP to around 5-7:
Blood gases improved despite decreased minutes ventilation: