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BJA Advance Access originally published online on April 19, 2009
British Journal of Anaesthesia 2009 102(6):875-881; doi:10.1093/bja/aep077
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© The Author [2009]. Published by Oxford University Press on behalf of The Board of Directors of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournal.org

Assessing the performance of the Whisperflow® continuous positive airway pressure generator: a bench study

G. W. Glover and S. J. Fletcher*

Intensive Care Unit, Bradford Teaching Hospitals NHS Foundation Trust, Duckworth Lane, Bradford BD9 6RJ, UK

* Corresponding author. E-mail: sjfletcher{at}doctors.org.uk

Background: There are few data describing the performance of the Whisperflow® continuous positive airway pressure (CPAP) generator.

Methods: (i) (a) A static test of 11 Whisperflow devices examining maximum flow generation with no load and with 2.5, 5, 7.5, 10, 15, and 20 cm H2O valve loading, at varying FIO2. (b) CPAP valves (Accu-peep®, Vital Signs, Totowa, NJ, USA) were tested by measuring mean upstream pressure at varying flows in five valves (2.5, 5, 7.5, 10, 15, and 20 cm H2O). (ii) We measured the mean and minimum inspiratory mask pressure generated by a representative Whisperflow device in a model of spontaneous respiration. Measurements were made with combinations of FIO2, ventilatory frequency, tidal volume, and valve loading similar to those encountered in clinical practice.

Results: (i) (a) The flow generated by the Whisperflow valves decreases with increasing valve load and increasing FIO2 (from 140 to 20 litre min–1). (b) The CPAP valves maintain the required pressure within acceptable limits against varying flow. (ii) At all permutations, the mean inspiratory mask pressure was significantly lower than that required. At high inspiratory flow rates, the minimum inspiratory pressure approached atmospheric pressure.

Conclusions: The Whisperflow may not perform as expected. Clinicians should be cautious when using this device, particularly with high FIO2 and CPAP valve load. The flow setting should be set at maximum. Failure of CPAP therapy may be due to failure of the generator. Further in vivo data are required.

Keywords: equipment, ventilators; ventilation, continuous positive pressure


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E-letters:

Read all E-letters

Continuous flow positive airway pressure generator in critical ill patients: a moratorium
Pedro Caruso, et al.
British Journal of Anaesthesia, 21 Sep 2009 [Full text]
Response to: Continuous flow positive airway pressure generator in critical ill patients: a moratorium
Guy W Glover, et al.
British Journal of Anaesthesia, 12 Oct 2009 [Full text]
Evaluation of the Whisperflow CPAP generator
Stephen J Fletcher, et al.
British Journal of Anaesthesia, 14 Oct 2009 [Full text]

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