Dear Sir, Dr Hawkes is right, if a gas flow meter that will deliver very high flows when turned up to its maximum flow, which may be over 80 L/min, is used with the Neopuff then if the flow is increased about the set level dangerously high levels of PIP and PEEP will be delivered. What is not commonly known is that some flow meters that are marked to deliver a flow from 0 to 15 L/min can deliver these very high flows which will overwhelm the pressure control valves in the Neopuff. A flow meter should never be used with the Neopuff that can deliver a maximum gas flow above 15 L/min. The practical message for all who use the Neopuff is that it should be used according to the manufacturer’s instructions. • The recommended operating gas flow range is 5 to 15 L/min. It specifically says, “Do not attempt to use a flow higher than 15 L/min". • Adjust the gas supply to the desired flow rate between 5 and 15 L/min then set the PIP and PEEP. • If the flow rate increases from 5 to 15L/min, peak pressure typically increases approximately 8 cm H2O/mbar. • The Neopuff should only be used on a baby after checking that correct pressures will be delivered to the baby. If the Neopuff PIP and PEEP are set with a flow of 5 L/min then if the flow is increased to 10 L/min the PEEP will rise to about 15 cm H2O and the PIP will be similar to, or just above the set PIP even when max PIP is set very high. If the flow is increased to 15 L/min the PEEP rises to about 24 cm H2O and PIP is similar to, or just above the set PIP even when max PIP is set very high. The effect of increasing the flow to 15 L/min will be much less if the PIP and PEEP were set at a flow of 10 l/min at the start. The practical clinical messages are simple 1) Pick a flow you are going to use, we suggest 8 L/min should be more than adequate, set the PEEP and PIP and then don’t alter the flow. 2) If the PEEP and PIP are not being delivered this is due to a large leak between the mask and face and that should be remedied by altering mask position and hold and not by increasing the flow. Yours sincerely, Colin Morley, Georg Schmoelzer, Peter Davis

Dear Editor,

We would like respond to the eLetter from Dr Schmoelzer et al, regarding our paper entitled "Potential Hazard of the Neopuff T-Piece Resuscitator in the Absence of Flow Limitation".

Dr Schmoelzer et al have verified our findings that even an increase in flow from 5-15L/min will bring about a four-fold increase in PEEP, a serious potential hazard of the Neopuff. His failure to reproduce our maximum PIP was due to his use of a lower flush flow meter.

We encourage all users of this device to investigate the effects of changing gas flow on their own systems, in order to be aware of the potential hazards of the Neopuff device. We stand by the findings of our study that there is a "Potential Hazard with the Neopuff T-Piece Resuscitator in the absence of flow limitation".

Competing Interests: None

Dear Editor,

With great interest we read the article “Potential hazard of the Neopuff T- piece resuscitator in the absence of flow limitation” by Hawkes CP and colleagues.

We were concerned by the possibility of exceeding the set Pmax during positive pressure ventilation with a Neopuff T-Piece Resuscitator, because we did not expect this, and so we decided to do our own studies. We used a Florian Respiratory Function Monitor (Acutronic Medical Systems, Zug, Switzerland) to measure airway pressures and gas flow. The flow sensor and pressure measurement device was placed between the Neopuff and a test lung. We did not have a digital flow meter to measure the precise gas flow rate and so used the flow from a standard clinical flow meter that would normally be used with a Neopuff. Data were recorded at 1000 Hz using a laptop computer with Spectra software (Grove Medical, London, UK), a program specifically designed for recording neonatal physiological data.

Our results are very different from the claims of Hawkes and colleagues. Our data showed an increase in PIP and PEEP with increasing gas flow at 10 and 15 L/min flow rate, as described in the article. PIP and PEEP increased from 20 / 5 cm H2O at 5 L/min to 27 / 20 cm H2O at 15 L/min. With a further increase to maximum gas flow the PIP and PEEP increased to 30.4 / 21.6 cm H2O. The set Pmax of 30 cm H2O was never exceeded. In addition, we never achieved their measurements for PIP and PEEP of 73 and 36 cm H2O with a gas flow of 10 L/min. At this flow we measured a PIP and PEEP of 24 and 16.5 cm H2O, respectively (See figure 1). We showed that the potential hazard of exceeding the set Pmax during positive pressure ventilation with a Neopuff does not occur.

Our results contradict the claims of Hawkes et al.

Competing interests: None