Comparison of Ram cannula and short binasal prongs in delivering CPAP on targeting mean oropharyngeal pressures - A randomised non-inferiority trial

Respiratory distress is one of the commonest problems in neonatal period which warrants NICU admission. Nasal continuous positive airway pressure (nCPAP) is the most frequent modality used to prevent respiratory failure, mechanical ventilation use and mortality. Use of CPAP in preterm infants helps in reduction in respiratory failure, need of mechanical ventilation and mortality. [1]

Nasal interface plays a very important role in nCPAP delivery. It should be easy to use and should deliver required CPAP pressures without causing any nasal trauma. Various interfaces available are nasopharyngeal tubes, short binasal prongs and nasal masks. Despite being inferior to nasal masks in CPAP delivery, short binasal prongs are one of the most commonly used nasal interfaces in delivering nasal CPAP due to their user-friendliness and easy availability. [2]

RAM cannula (Neotech, Valencia, CA) is FDA-approved for oxygen therapy but it’s off-label use in CPAP and NIPPV delivery is getting popular day by day. As it is made up of soft material and has an adapter attached to it, thus helps to reduce nasal injury, improve neonatal comfort, and helps in easy transition from NIPPV to CPAP support without changing interface. [3,4] Simulation studies have shown that Ram cannula leads to suboptimal pressure transmission, which may be ineffective in delivering CPAP if leak from the nostrils exceeds certain threshold margin. [5-9]

2.REVIEW OF LITERATURE :

As Ram cannula is gaining popularity as a newer mode of nasal interface to provide CPAP as well as NIPPV support, not much literature exists to provide evidence regarding failure rates of nasal CPAP delivery.

Previous studies were successful in showing that Ram cannula provides consistently lower set delivered oropharyngeal pressures as compared to short binasal prongs. [8,10] There is lot of ambiguity in results published regarding clinical outcomes such as need of invasive ventilation and failure rates of CPAP and NIPPV support. [4-9]

Studies till date have used barrier dressing on nasal septum to prevent nasal injuries, but mostly cannulaide have been used for either group, resulting in bias. [4,5,12,13] None of the studies have used cannulaide for both comparison groups in delivering nasal CPAP.

One of the latest non-inferiority randomized controlled trial comparing Ram cannula with Hudson prongs in preterm neonates admitted for respiratory distress was not able to prove the non-inferiority of Ram cannula with short binasal prongs. The study was underpowered due to small sample size and did not measure mean oropharyngeal pressures. [13]

A recent systematic review and meta-analysis showed no difference in nasal injury rates and concluded that no clinical benefit or harm can be ruled out for outcome of need of invasive mechanical ventilation and need for surfactant, and adequately powered studies are needed to evaluate the efficacy of Ram cannula compared with other interfaces. [11]

JUSTIFICATION:

Ram cannula is superior in preventing nasal injuries in neonates but delivers less oropharyngeal pressures. Previous studies have used cannulaide either for Ram cannula or Hudson for comparison of nasal trauma and leak, resulting in bias. So far none of the studies have reported the efficacy of Ram cannula in delivering CPAP by targeting delivered mean oropharyngeal pressures. We hypothesize that Ram cannula is non inferior to short binasal prongs if delivered mean oropharyngeal pressures are targeted.