| Reservoir | Demand pulse | Noninvasive open ventilator with oxygen[1] | Transtracheal catheter (placed surgically) | |
| Mechanism | Stores oxygen during exhalation | Delivery during early inspiration | Delivers 50 to 250 mL pulses | Store, bypass dead-space |
| Efficiency | 2:1 to 4:1 | 3:1 to 7:1 | Not available | 2:1 to 3:1 |
| High-flow | 16 L/m | Not applicable | Larger pulses | 16 L/m |
| Comfort | Adequate | Adequate | Adequate | Good after insertion; requires daily cleaning |
| Cosmetics | Obtrusive | Adequate | Adequate | Excellent |
| Complications | Rare | Mechanical failure | Mechanical failure | Mucous plug, bleeding, malposition |
