A Randomized Controlled Trial of Synchronized Nasal Intermittent Positive Pressure Ventilation in RDS

V Bhandari; R G Gavino; J H Nedrelow; P Pallela; A Salvador; R A Ehrenkranz; N L Brodsky;

Disclosures

December 05, 2007

In This Article

Discussion

With increased survival of ELBW infants, there is renewed interest in minimizing the need for prolonged mechanical ventilation with the use of non-invasive ventilation, to reduce ventilator-induced trauma and oxygen toxicity. NCPAP has been advocated,[9,10,11,12] but has not achieved equivalent success in the hands of all investigators. Our attempts to use NCPAP as a primary mode of respiratory support led to limited success as infants continued to have apneic/bradycardic episodes and/or significant respiratory failure, based on clinical and blood gas parameters. Given the potential benefits of avoidance of endotracheal intubation, namely, decreased laryngeal and tracheal injury, decreased incidence and severity of BPD, and decreased nosocomial pneumonia and sepsis,[15,25,26] a decision to utilize SNIPPV as an alternative mode of ventilation was made.

SNIPPV has been previously shown to be significantly better than NCPAP as a mode of extubation in recovering infants with RDS.[8] As a result of that study,[8] SNIPPV was established as the preferred method for extubation in infants recovering from RDS at our institutions. The efficacy and safety of this technique has also been reported at other sites[15,16,27] and has been shown to be effective when introduced into a NICU setting where it was previously not in use.[28,29] The primary mode of SNIPPV has been found to be feasible and effective in the larger premature infant in the acute phase of RDS.[15]

In the present study, use of SNIPPV as a primary mode of ventilation in infants <32 weeks of gestation and birth weights 600 to 1250 g with RDS decreased the need for PPV. The study patients were well matched in terms of maternal demographics, BW, GA, severity of RDS (as evaluated by surfactant doses) as shown in Table 1 . However, infants in the SNIPPV group had decreased BPD/death ( Table 2 ). There were no significant differences in the blood gases, other neonatal morbidities or MDI/PDI scores on follow-up. In the recently reported results of the COIN (CPAP or Intubation at birth) Trial (presented at Hot Topics 2006), 303 babies were randomized to the ventilation group, while 307 received NCPAP. There were no significant differences in death or BPD (using the 36 weeks PMA definition) or in any of the major morbidities in the two groups.

Recently, Kiciman et al.[30] have shown that thoracoabdominal motion asynchrony decreased in neonates on nasal ventilation, and that nasal IMV decreased flow resistance through the nasal prongs and improved the stability of the chest wall, resulting in improved pulmonary mechanics. Friedlich et al.[15] have suggested that addition of a PIP above PEEP by using SNIPPV not only adds intermittent distending pressure above PEEP, but also increases flow delivery in the upper airway. Furthermore, Moretti et al.[31] found that application of SNIPPV was associated with an increase in tidal and minute volumes as compared to NCPAP in the same infant. It is also possible that SNIPPV could be creating an inadvertent PEEP that would allow further recruitment of alveoli and higher functional residual capacity. Recently, Aghai et al.[32] have reported that infants on SNIPPV have decreased work of breathing.

The babies on CV were on the IMV mode, whereas the SNIPPV babies, by design were receiving synchronized ventilation. Though studies on CV have not shown any benefit with synchronization,[33] it is possible that the benefits from SNIPPV could be, in part, from synchronization. Recent reports, however, have reported success with NIPPV;[34] though, no RCT comparing synchronized versus non-synchronized NIPPV have been reported.

This study has some limitations. The major limitation is the sample size. Besides the strict GA, birth weight and timing of surfactant administration criteria, 'too sick' patients were excluded. Since this was a pragmatic study to show feasibility with a fairly novel technique in sick preterm babies, babies with severe RDS (OI>9, FiO2>0.8) were excluded, as per the request of the IRB at both sites. In the infants with mild-moderate RDS, major reasons for non-recruitment were the inclination of the attending neonatologists to trial NCPAP after delivery resulting in delayed intubation (and the subsequent administration of surfactant, if required, beyond 1 h after birth), and delayed/unsuccessful arterial line placements. This also hampered obtaining consents in a timely manner. Other reasons included loss of site investigators and conflict with other RCT. It took a year for the SNIPPV technique to be introduced, established and the study protocol to be approved by the IRB, before enrollment of patients at Yale site. With the long study duration and type of patient enrollment, a potential for selection bias exists. Some secondary outcomes could have been negative due to small numbers. To the best of our knowledge, however, this is the first RCT of primary mode SNIPPV in such a patient population.

In conclusion, in this RCT, the primary mode SNIPPV was found to be feasible as a method of ventilation in very low birth weight infants with RDS. Recently reported results[35,36] should spur the need for this finding to be tested in an adequately powered RCT.

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