The Science Journal of the American Association for Respiratory Care

1999 OPEN FORUM Abstracts

Auto-Mode: Is it Really That Simple?

Richard Lawhead, BS, RRT, CPFT, P/P Spec., K.S. Anand, MBBS, D.Phil., Arkansas Children's Hospital

Background: Siemens Servo Ventilator 300A has a closed loop ventilation feature called Automode. Automode allows the ventilator to automatically switch between a control mode of ventilation and a spontaneous mode when certain parameters are met. Two consecutive triggering efforts from a patient will change the ventilator from a control mode to a spontaneous mode. If the patient stops breathing for a pre-determined period of time, the ventilator automatically switches back to a control mode (5sec for neonate; 8sec for pediatric; 12sec for adult).

Discussion: We report a patient who was managed initially with PRVC/VS Automode. The patient is a 10yr, 41kg male who was intubated and admitted to the PICU with the diagnosis of pneumonia. The patient was placed on the SV 300A ventilator with the following settings: PRVC 20/Vt 300/35%/+10. The patient selector had to be placed in the adult mode secondary to the flow limitation of 33 lpm in the pediatric setting. The Automode function was initiated at the beginning of Day 2. During the patient's stay on the ventilator, the ventilator settings often had to be manipulated in the attempt to manage Automode effectively. When the patient's RR was below the CMV rate, the Vt and PIPs increased substantially. The CMV rate was reduced to combat this. However, when the patient automatically switched back into PRVC, the lower rate was not sufficient to maintain adequate blood gases. After many manipulations, the Automode function was finally turned off and the patient successfully weaned and extubated utilizing PRVC and VS managed more conventionally.

Time pH pCO2 pO2 RR Vtset Vtdel PIP Mode
Day 2 @ 0030 7.25 81 80 12 255 390 36 Auto-VS
Automode turned OFF (Day 2 @ 0100)
Day 2 @ 0600 7.36 59 92 20 300 300 29 PRVC
Automode turned ON (Day 2 @ 0830)
Day 2 @ 1200 7.30 64 87 20 300 300 32 Auto-PRVC
Day 2 @ 1500 12 300 440 40 Auto-VS
Day 2 @ 1630 20 300 300 30 Auto-PRVC
Day 2 @ 1800 7.32 61 104 14 300 450 42 Auto-VS

Conclusions: The simplistic mechanism used to switch patients between control and spontaneous modes of ventilation and the multiple functions of the CMV rate knob may increase difficulty in the ventilator management of sick children with Automode on.


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