Case Studies
Back
10/1/1999
Laboratory Evaluation of Four Portable Ventilators (PVTs)
Reprinted from Respiratory Care Vol. 44, No. 10, October, 1999
Traditionally, PVTs have high imposed work of breathing (WOBi). Newer PVTs include flow triggering and PSV to minimize WOBi. We compared the WOBi and response time (RT) of 4 PVTs on a lung mode.
A two-chambered test lung (TTL) was modified to mimic spont breathing. An Evita 4 (Drager) powered the "drive" lung at 3 volume and flow conditions:
- 300 ml @ 40 L/min,
- 500 ml @ 60 L/min, and
- 800 ml @ 80 L/min.
TTL characteristics were C of 56 ml/cmH2O and R of 5 cmH2O/L/sec. PVTs (Achieva, TBird, 740, LTV) were attached to "pt" lung with flow trigger of 2 and set at PEEP/PSV combinations of: 0/0, 0/10, 5/0, and 5/10. Five breaths at each setting were analyzed and data recorded = WOBi, peak negative pressure (PNP), RT and Vt.
WPBi was higher with Achieva with PEEP set. Table 1 shows results (mean +/- SD) at 0/10 (cond #2). Table 2 shows results at 5/0 (cond #2).
Table 1
| WOBi(mJ/L) | PNP (cmH20) | RT (Sec) |
|---|
| Achieva 0.2 | 0.2 +/- 0.02 | -0.5 +/- 0.03 | 0.12 +/- 0.02 |
|---|
| LTV1000 | 0.9 +/- 0.2 | -0.9 +/- 0.1 | 0.14 +/- 0.02 |
|---|
| TBird | 0.06 +/- 0.02 | -0.1 +/- 0.03 | 0.14 +/- 0.02 |
|---|
| 740 | 1.0 +/- 0.3 | -1.24 +/- 0.06 | 0.17 +/- 0.02 |
|---|
Table 2
| WOBi(mJ/L) | PNP (cmH20) | RT (Sec) |
|---|
| Achieva | 67.0 +/- 3.0 | 0.41 +/- 0.2 | 0.5 +/- 0.04 |
|---|
| LTV1000 | 18.0 +/- 1.5 | -0.1 +/- 0.1 | 0.25 +/- 0.02 |
|---|
| TBird | 13.0 +/- 0.2 | 2.30 +/- 0.03 | 0.27 +/- 0.02 |
|---|
| 740 | 8.0 +/- 1.3 | 3.6 +/- 0.1 | 0.32 +/- 0.02 |
|---|
WOBi on these PVTs is clinically acceptable and may be minimized by adding PSV.
Reprinted from Respiratory Care Vol. 44, No. 10, October, 1999 By Daedalus Enterprises. Inc., Dallas, Texas
Back