Evaluation of a Nasal Cannula in Noninvasive Ventilation Using a Lung Simulator

Abstract

BACKGROUND: Nasal noninvasive ventilation (NIV) is a common form of noninvasive respiratory mode used in newborn infants. A next-generation nasal cannula (Neotech RAM cannula) has recently been used to provide nasal NIV. The impact of the Neotech RAM cannula on the delivery of pressure needs to be studied. METHODS: In this ex vivo experimental design, a lung simulator (IngMar ASL 5000, version 3.4) was programmed to model a neonate (ϳ1-3 kg of body weight) with normal-to-moderately affected lungs. We used a Covidien PB840 ventilator with NIV software activated to compensate for leaks. Nasal NIV was set at peak airway pressures of 15, 20, and 25 cm H 2 O and PEEP of 5, 6, and 7 cm H 2 O. Three sizes of the Neotech RAM cannula were used (prong outer diameters of 3.0, 3.5, and 4.0 mm). The nose was designed to keep the leak of the nares by the prongs to 30%. We also created a worst case leak (58% leak) by using the largest simulated nostril diameter with the smallest diameter Neotech RAM cannula prong. The outcome measure was the difference in pressures, referred to as leak effect, measured by the lung simulator relative to the set peak airway pressure and PEEP on the ventilator. RESULTS: For the interface with 30% leak, leak effects of peak airway pressure during simulated nasal NIV were similar with all Neotech RAM cannula sizes, with 63-75% of peak airway pressure and 70 -90% of PEEP being transmitted across the nasal interface. The worst case scenario produced a 92% leak effect in peak airway pressure and PEEP. CONCLUSIONS: When used with < 30% leak, the Neotech RAM cannula interface results in clinically acceptable transmission of pressures. With > 50% leak, a clinically negligible amount of pressure is transmitted to the artificial lungs.

Comparison of Bubble CPAP Devices Using RAM Cannula for Extubation Failure in Very Low Birth Weight Infants: Randomized and Cohort Studies

“…Similar reductions in pressure transduction (up to 60%) have been reported with micro-Preemie, Preemie, and Newborn RAM © cannulas using ventilator-derived CPAP and advanced test lungs [16, 17]. When the RAM © Preemie cannula was tested with NIPPV, transmitted peak inspiratory pressure was 65% of set value, and PEEP was 70% of set value [18]. In contrast, when the BabiPlus © was tested by Poli et al[4] with prongs recommended by the manufacturer, the pressure at the prongs, when set to 6 cm H 2 O, was 6.5 ± 0.01 cm H 2 O.…”

Evaluating the Effect of Flow and Interface Type on Pressures Delivered With Bubble CPAP in a Simulated Model

“…However, the risk associated with a tight seal far outweighs the clinical benefit by increasing the propensity for skin breakdown. 12 Iyer et al 18 have shown in an ex vivo experimental design with a lung simulator that the appropriate size interface is imperative: When the cannula size was too small relative to the nasal model diameter, pressure transmission was significantly reduced, resulting in a minimal amount of pressure being applied to the model.…”

Effects of Leak Compensation on Patient-Ventilator Synchrony During Premature/Neonatal Invasive and Noninvasive Ventilation: A Lung Model Study

“…com). We set compliance and resistance values for each model by reviewing previous neonatal bench studies [11][12][13][14][15] as well as clinical studies of lung function tests in preterm infants, [16][17][18][19][20][21] specifically using individual references for each weight group: 0.5 kg, 17,18 1 kg, 19 2 kg, 20 and 4 kg 21 (compliance varying from 0.5 to 5 mL/cm H 2 O/kg; resistance varying from 50 to 350 cm H 2 O/L/s). We calculated resistance values of each endotracheal tube/nasal cannula by using pressure drop across the interface measured with the PTS 2000 (Mallinckrodt, Dublin, Ireland) and average peak flow during invasive ventilation and NIV, and we confirmed that total respiratory resistances were within the range that we estimated for each model ( Table 2).…”

“…In the NIV modes, a nasal cannula (RAM, Neotech, Valencia, California) was used for NIV. 13,29 The nasal cannula was affixed to the model nares using a 22-mm inner diameter plastic adapter (Adapter 962-E, Unomedical, McAllen, Texas). The size of the nasal cannula was selected as follows: "micro preemie" (2.5-mm outer diameter) for 0.5 kg, "preemie" (3.0-mm outer diameter) for 1 kg, "newborn" (3.5-mm outer diameter) for 2 kg, and "infant" (4.0-mm outer diameter) for 4 kg.…”