The Science Journal of the American Association for Respiratory Care

1996 OPEN FORUM Abstracts

LABORATORY EVALUATION OF THE DRAGER OXYLOG 2000 TRANSPORT VENTILATOR.

Robert S Campbell RRT, Richard D Branson RRT, Jay A Johannigman MD. University of Cincinnati Medical Center, Cincinnati, OH 45267.

Purpose: To evaluate a new transport ventilator in respect to delivery of set tidal volume (V_{T}) and PEEP, accuracy of minute ventilation (V_{e}) and airway pressure measurement, demand valve responsiveness, alarm function, and battery duration. Method: The Oxylog 2000 was attached to a two-chambered test lung (TTL, Michigan Instruments) equipped with pressure, flow, and volume monitoring software. Ten breaths were recorded at each combination of V_{T} (0.1, 0.5, 1.0, and 1.5 L), C_{L} (0.1, 0.04, and 0.02 L/cmH_{2}O), and air-mix (AM) switch (on, off) with the ventilator in the CMV mode at a rate of 10 using a 1:1.5 I:E ratio. PEEP was randomly set to 0.5, 10, and 15 cmH_{2}O and measured within the TTL using an RT-200 calibration analyzer. Volume and pressure measured within the TTL were compared to those reported by the ventilator (Student's T-test). Responsiveness of the demand valve was evaluated by measuring the peak negative pressure (PNP) at CPAP levels of 0, 5, and 10 cmH_{2}O after modifying the TTL to simulate spontaneous breathing with demand flow of 30 and 60 L/min. All alarm functions were evaluated by creating known conditions above or below each alarm threshold. Both the alkaline and NiCd battery duration was evaluated by running the unit until the low battery alarm sounded and gas delivery ceased. Results: Table 1 shows the V_{T} (L) delivery and V_{e} (L/min) measured at all C_{L} and AM settings using a 1.0 L V_{T} at a rate of 10 bpm. Table 2 shows the actual PEEP level and PNP with 60 L/min demand flow for each PEEP setting.

Table 1 Table 2

Compliance 0.10 0.04 0.02 Set Peep Applied PEEP PNP

V_{T}AM ON 1.11 .97* .83*$# 0 2.0 -5

V_{T}AM OFF 1.20 1.1 1.1 5 8.8 -7

V_{e}AM ON 10.2 9.4* 7.6*$# 10 13.9 -10

V_{e}AM OFF 11.0 10.7 9.3$# 15 20.0 N/A

*=p < 0.05 vs AM off. $=p < 0.05 vs C_{L} 0.1. #=p < 0.05 vs C_{L} 0.04.

The NiCd battery provided ventilation for 5 hours, 5 minutes. The Alkaline battery pack provided ventilation for 3 hours, 37 minutes. The "change battery" warning provided three minute notice prior to termination of ventilation. All alarms operated to manufacturers specifications. Discussion: Delivered V_{T} dropped predictably as C_{L} was reduced with the AM on. Measured V_{e} adequately reflects actual minute ventilation delivery. Applied PEEP exceeded both set and measured PEEP at all settings. Demand valve triggering was sluggish and worsened with increasing PEEP. Conclusion: The Oxylog 2000 provides adequate V_{T} delivery and V_{e} measurement in both CMV and SIMV modes at normal and moderately reduced C_{L}. AM setting should be used cautiously when C_{L} is greatly reduced. Patients should be closely monitored during spontaneous breathing for signs of increased work of breathing.

Reference: OF-96-166

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