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(Continued)

Table 3.

746

Normal Resistance and Low Compliance

Normal Resistance and Normal Compliance

High Resistance and Normal Compliance

PEEP (cm H O)

2

PIP (cm H O)

2

RR (br/min)

T

V (mean SD mL)

PEEP (cm H O)

2

PIP (cm H O)

2

RR (br/min)

T

V (mean SD mL)

PEEP (cm H O)

2

PIP (cm H O)

2

RR (br/min)

T

V (mean SD mL)

5

30

15

507 1.1

5

16

15

532 0.9

5

20

15

526 2.0

Bio-Med Devices Crossvent 3*

PERFORMANCE COMPARISON OF 15 TRANSPORT VENTILATORS

5

6 6 4 5

measured VT was 10% different than the set VT, and in 19 of these tests the measured RR was 10% different than the set RR.

31

30

520 1.1

9

29 32 23

26

15 30 14

29

475 1.3 488 2.9 390 8.7† 424 6.9†

7 10 5 6

Seventy-eight individual tests were performed at a VT of 500 mL. In 28 of these tests the measured VT was

  • 10% different than set VT, and in 15 of these tests the

RR was 10% different than the set RR. The inability to meet the target VT is partially explained by compressible volume loss, since none of these units compensates for the volume loss due to compression. The compressible vol- ume was 0.91 0.39 mL/cm H2O (range 0.43–1.65 mL/cm H2O), and since the PIP values were at most in the mid- 30s, only about one third of the volume loss can be attrib- uted to compressible volume. Two of the ventilators (Vor- tran RespirTech Pro and Percussionaire TXP) were not included in the bench test because their design was incom- patible with our protocol; they did not incorporate readily identifiable parameter settings.

18

30

523 0.8

8

25

30

507 1.5

Bio-Med Devices Crossvent 3‡

13 16 13

15

15 30 14

29

467 3.2 489 2.7 429 5.8† 442 5.8†

6 7 6 6

15 29 14

20

15 30 15

29

472 0.6 473 1.6 410 4.0† 436 5.0†

Bird Avian* Bird Avian‡ Pneupac Compac 200* Pneupac Compac 200‡

*Respiratory rate set at 15 breaths/min †Measured value was 10% different from the setting on the ventilator ‡Respiratory rate set at 30 breaths/min V tidal volume. RR respiratory rate. br/min breaths/min. PIP peak inspiratory pressure. PEEP positive end-expiratory pressure. NA not applicable.

T

Three of the ventilators were unable to meet some of the test conditions, due to their designs. The Carevent ATVachieves VT by setting V˙ E and RR, with a maximum V˙ E of 14 L/min and an inspiratory-expiratory ratio of 1:2 to es- t a b l i s h T I . T h e P n e u p a c C o m p a c 2 0 0 a l s o a c h i e v e s V T b y s e t t i n g V ˙ E a n d R R w i t h a m a x i m u m V ˙ E o f 1 4 L / m i n . T Life Support Products AutoVent 2000 has 2 controls: VT and RR, with a maximum RR of 17–18 breaths/min. In- spiratory time and flow vary with changes in V˙ E. At high RR settings the inspiratory-expiratory ratio is 1:1. h e

Animal Evaluations

We evaluated 14 ventilators with healthy and saline- lavage-injured sheep. We were unable to evaluate the Vor- tran RespirTech Pro in either animal model because the weight of the sheep (20–31 kg) was below the operating range of this ventilator (minimum 40 kg). All of the 14 ventilators tested were capable of ventilating the healthy

lungs (Fig. 1). Ventilators without F and PaCO2 targets, but exceeded the P IO2 aO2

control met the pH target. With all the

ventilators, hemodynamics were stable throughout the tests. Four ventilators (VersaMed iVent, Newport HT50, Bio- Med Devices IC2A, and Percussionaire TXP) met all the targets when ventilating injured lungs (Fig. 2). Seven ven- tilators (Pulmonetic Systems LTV 1000, Bird Avian, Oce- anic Medical Products Magellan, Pneupac Parapac Trans- port 200D, Pneupac Parapac Medic, Bio-Med Devices Crossvent 3, and Carevent ATV) successfully ventilated the lungs of only one of the 2 lung-injured animals. The remaining 3 ventilators (Univent Eagle 754, Pneupac Com- pac 200, and Life Support Products AutoVent 2000) failed to meet the ventilation targets in either of the 2 lung- injured sheep used. In all cases of failure, the PaCO2 and/or pH targets were not met. In most cases, the RR setting was the limiting parameter. All 14 ventilators met the oxygen-

RESPIRATORY CARE JUNE 2007 VOL 52 NO 6

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