Delivery of sevoflurane using a neonatal ventilator.

BACKGROUND

Most anesthetic ventilators are designed to cope with a wide range of patient sizes and may lack precision at the lowest end of the minute volume scale. Neonatal intensive care ventilators on the other hand are designed specifically for this patient group, but are not able to deliver volatile anesthesia.

AIMS

We aimed to adapt the neonatal ventilator currently in use in our institution to deliver sevoflurane by incorporating a vaporizer and a scavenging system.

METHODS

We used a Diamedica draw-over vaporizer incorporated into the ventilator circuit and a custom designed open interface scavenging system. A number of safety measures are described to ensure that this equipment is correctly inserted into the circuit.

RESULTS

Bench testing revealed that the vaporizer output is linear and stable within the circuit flow range 4-8 L/min in all modes except high frequency oscillation where concentrations are not predictable. The scavenging system was found to be effective and did not affect volumes, pressures or waveforms when ventilating a test lung over a wide range of flows and pressures. This remained the case over the full range of scavenger flow adjustment.

CONCLUSION

The addition of a Diamedica vaporizer to a Fabian neonatal ventilator was shown in bench testing to provide stable, linear vapor concentrations without compromise of ventilator function. The system should not be used in high frequency oscillation mode because concentrations will exceed those expected and will not maintain a linear relationship with the vaporizer setting.