AIM: The current recommendation in setting up the Neopuff is to use a gas flow of 5-15 L/min. We investigated if the sensitivity of the positive end expiratory pressure (PEEP) valve varies at different flow rates within this range. METHODS: Five Neopuffs were set up to provide a PEEP of 5 cm H(2) O. The number of clockwise revolutions to complete occlusion of the PEEP valve and the mean and range of pressures at each quarter clockwise revolution were recorded at gas flow rates between 5 and 15 L/min. Results: At 5, 10 and 15 L/min, 0.5, 1.7 and 3.4 full clockwise rotations were required to completely occlude the PEEP valve, and pressures rose from 5 to 11.4, 18.4 and 21.5 cm H(2) O, respectively. At a flow rate of 5 L/min, half a rotation of the PEEP dial resulted in a rise in PEEP from 5 to 11.4cm H(2) O. At 10 L/min, half a rotation resulted in a rise from 5 to 7.7cm H(2) O, and at 15 L/min PEEP rose from 5 to 6.8cm H(2) O. CONCLUSION: Users of the Neopuff should be aware that the PEEP valve is more sensitive at lower flow rates and that half a rotation of the dial at 5 L/min gas flow can more than double the PEEP.AIM: The current recommendation in setting up the Neopuff is to use a gas flow of 5-15 L/min. We investigated if the sensitivity of the positive end expiratory pressure (PEEP) valve varies at different flow rates within this range. METHODS: Five Neopuffs were set up to provide a PEEP of 5 cm H(2) O. The number of clockwise revolutions to complete occlusion of the PEEP valve and the mean and range of pressures at each quarter clockwise revolution were recorded at gas flow rates between 5 and 15 L/min. Results: At 5, 10 and 15 L/min, 0.5, 1.7 and 3.4 full clockwise rotations were required to completely occlude the PEEP valve, and pressures rose from 5 to 11.4, 18.4 and 21.5 cm H(2) O, respectively. At a flow rate of 5 L/min, half a rotation of the PEEP dial resulted in a rise in PEEP from 5 to 11.4cm H(2) O. At 10 L/min, half a rotation resulted in a rise from 5 to 7.7cm H(2) O, and at 15 L/min PEEP rose from 5 to 6.8cm H(2) O. CONCLUSION: Users of the Neopuff should be aware that the PEEP valve is more sensitive at lower flow rates and that half a rotation of the dial at 5 L/min gas flow can more than double the PEEP.