5. Delivery device of continuous positive
airway pressure (CPAP)
When the first use of CPAP was described it was classical
bubble CPAP delivered through the expiratory limb of ventilatory
circuit dipped into a column of water. The length of tube
under the water level was used to describe the amount of
CPAP in cm of H2O. Since then bubble CPAP has gone many
innovations and now specially designed bubble CPAP equipment’s
are available. CPAP can also be delivered through a
ventilator; however bubble CPAP is cheap and more useful in
resource limited settings. Kahn et al described unpredictable
delivery of pressure while using bubble CPAP and its dependence
on the flow of gases.22 Some claim that bubble CPAP by
virtue of producing noise factor may be more effective as
compared to CPAP delivered through ventilator.23 Many
studies have shown no difference in these two techniques as
these studies recruited small number of subjects. Gupta et al
reported in an RCT that bubble CPAP was more effective in
terms of extubation and need for oxygen supplementation in
preterm neonates ventilated for less than 14 days, when
compared to CPAP delivered through ventilator.24 The bubbles
may induce some oscillatory effects to improve oxygenation.
Further research is ongoing to device ways to improve this
effect.