Efficacy of a New Technique -"IN-REC-SUR-E"- in Preterm Neonates With RDS

EFFICACY OF A NEW TECHNIQUE -"IN-REC-SUR-E"- IN PRETERM NEONATES WITH RESPIRATORY DISTRESS SYNDROME DURING NON INVASIVE VENTILATION: A RANDOMIZED CONTROLLED TRIAL

BACKGROUND The initial stabilization on Continuous Positive Airway Pressure (CPAP) and provision of rescue surfactant only when necessary is at least as beneficial and quite possibly preferred over the standard therapy of intubation of all infants at risk in the delivery room and subsequent support with mechanical ventilation (2-4). The percentage of CPAP failure in the newborns of 25-28 weeks' gestation is 45 % (30/66) in the Australian experience (5), higher than that reported by Ammari et al. (25 %) (6) and similar to that reported by De Jaegere et al. (50 %) (7) and in the COIN trial (46 %) (2). As a potential alternative, the INSURE (INtubate, SURfactant, Extubate) approach (8) is very attractive. Recently, several studies have investigated the effectiveness of the association between non-invasive ventilation and surfactant, administered by transient intubation (INSURE), showing that it is effective in preventing the need for mechanical ventilation. Although beneficial in clinical practice, the INSURE method cannot be universally applied to all preterm neonates with Respiratory Distress Syndrome (RDS) and is unsuccessful in a particular section of this population. The INSURE failure rate recently reported in preterm infants of different gestational age widely ranges from 19 % to 69 % (10, 11). Unfortunately, no randomized controlled trials have directly evaluated the efficacy of INSURE in extremely preterm neonates (<28 weeks gestation) (8). Nevertheless, the data of the "Sustained Lung Inflation (SLI) study" (14) recently conducted on infants with GA 25+0- 28+6 weeks showed that nasal CPAP failure and need for Mechanical Ventilation (MV) at 72 hours of life was 53 % in the SLI group and 65 % in the control group (only nasal CPAP). In this study surfactant was preferably administered with the INSURE approach at a Fraction of Inspired Oxygen (FiO2) threshold of 0.40 and then it could be reasonably argued that at least 50 % of 25-28 weeks' gestation infants, even if receiving a SLI maneuver and the INSURE treatment for CPAP failure, undergoes mechanical ventilation in the first 72 hours of life for unsuccessful INSURE. One of the possible mechanisms responsible for the unsuccessful INSURE, requiring subsequent re-intubation and mechanical ventilation is the inability of the preterm lung with RDS of achieving and maintaining an "optimal" Functional Residual Capacity (FRC). Prophylactic or early rescue surfactant administration before alveolar recruitment probably results in an uneven surfactant distribution to already open alveoli thus resulting in poor clinical response to the first surfactant treatment. We, therefore, seek to compare the application of a recruitment manoeuver - in High-Frequency Oscillatory Ventilation (HFOV) modality - just before the surfactant administration, followed by rapid extubation (INtubate-RECruited-SURfactant-Extubation: IN-REC-SUR-E) with INSURE alone in spontaneously breathing preterm infants requiring nasal CPAP as initial respiratory support and reaching pre-defined CPAP failure criteria, for evaluating its effectiveness in decreasing the need of MV and improving respiratory outcome.

Study design This will be an unblinded multi-center randomized trial of IN-REC-SUR-E vs. IN-SUR-E in infants born at 24+0-27+6 weeks' gestation.

Sample size The investigators hypothesized that a recruitment manoeuver (in HFOV modality) before surfactant administration might decrease of the need of subsequent mechanical ventilation during the first 72 hours of life from 50 % (2, 5, 7) to 30 %. The investigators calculated that 103 newborns must be enrolled in each group to detect this difference as statistically significant with 80 % power at 0.05 level.

Randomisation Infants at each unit will be block (1st block: gestational age from 24+0 to 25+6 weeks; 2nd block: gestational age from 26+0 to 27+6 weeks) randomly assigned to a treatment group using automatically generated sealed envelopes which will be prepared at Policlinico A. Gemelli Hospital in Rome and then distributed to participating centers. Permutated block randomization with 1:1 randomization between the two arms will be used.

Blinding The study will not be blinded, and the staff performing the study also will take care of the infants later on. However, the decision to start mechanical ventilation will be made by clinicians other than the investigators and, moreover, parents, nurses involved in patient care and researchers assessing study end-points will be blinded to the nature of the study treatments. To minimize bias, strict criteria and definitions will be maintained during the trial.

Management in the Delivery Room Positive pressure with a neonatal mask and a T-piece system (Neopuff Infant Resuscitator, Fisher and Paykel, Auckland, New Zealand) will be used to stabilize newborns after birth. All the neonates will receive one (or two) SLI manoeuver(s) (25 cmH2O for 10-15 seconds) (14) and will be transferred to the Neonatal Intensive Care Unit (NICU) in nasal CPAP (6 cmH2O). Infants will start mechanical ventilation in agreement with the American Academy of Paediatrics guidelines on neonatal resuscitation (16). In this latter case the babies will be excluded from the study (see exclusion criteria section, page 4).

CPAP Failure Criteria In the NICU, nasal CPAP will be given through nasal prongs/mask using the standard method of the single centre (ventilator, flow-dependent system) with an initial pressure of 6 to 7 cmH2O, in all infants. CPAP failure is defined if they met any of the following criteria: FiO2 ≥ 0.30 on nasal CPAP (17) to maintain pulse oximetry (SpO2) 87-94 %(18) for at least 30 minutes unless rapid clinical deterioration occurred, respiratory acidosis defined as pCO2 > 65 mmHg (8.5 kPa) and pH < 7.20 on arterial or capillary blood gas sample, apnea defined as >4 episodes of apnea per hour or >2 episodes of apnea per hour when ventilation with bag and mask will be required.

HFOV Recruitment manoeuver Infants in the IN-REC-SUR-E group will undergo the following approach: after intubation, HFOV will be delivered with the ventilator available in each NICU. The following initial ventilator setting will be advocated: Continuous Distending Pressure (CDP): 8cmH2O; Frequency: 10-15 Hz; Delta P: 15 cmH2O or Amplitude 30 % eventually increased - chest to be "visibly vibrating "-; I:E 1:2. Delta P (or amplitude) first and/or frequency subsequently will be adjusted to achieve a Tidal Volume (VT) of 1,5-2 ml/kg and/or to maintain the transcutaneous partial carbon dioxide pressure (TcPCO2) between 40 and 60 mmHg (5.3 and 8.0 kPa). The infants will be subjected to an open lung ventilation strategy aiming to recruit and stabilize the majority of collapsed alveoli/sacculi, using oxygenation as an indirect parameter for lung volume. Optimal recruitment is defined as adequate oxygenation using a FiO2 of 0.25 or less. Starting at 8 cmH2O, the CDP will be increased stepwise (2 cmH2O every 2-3 minutes) as long as SpO2 improves. The FiO2 will be reduced stepwise, keeping SpO2 within the target range (87-94 %). The recruitment procedure will be stopped if oxygenation no longer improves or if the FiO2 is equal to or less than 0.25. The corresponding CDP will be called the opening pressure (CDPO). Next, the CDP will be reduced stepwise (1-2 cmH2O every 2-3 minutes) until the SpO2 deteriorates (of at least 2-3 points). The corresponding CDP will be called the closing pressure (CDPC). After a second recruitment manoeuver at CDPO for 2 minutes, the optimal CDP (CDPOPT) will be set 2 cmH2O above the CDPC for at least 3 minutes (19). A chest radiograph at this point is advised.

Surfactant Treatment

Infants in the IN-REC-SUR-E arm will undergo the following approach: as soon as possible after the recruitment manoeuver (at CDPOPT) a dose of poractant alfa (Curosurf [Chiesi Farmaceutici, Parma, Italy]) of 200 mg/kg will be administered via a closed administration system in one-two aliquots (1-2 minutes). The tube position will be confirmed by auscultation. A temporary reduction of frequency may be necessary to increase the VT up to 2.5 ml/kg for improving the surfactant spreading.

Infants in the IN-SUR-E arm will undergo the following approach: after intubation, a dose of poractant alfa (Curosurf [Chiesi Farmaceutici, Parma, Italy]) of 200 mg/kg will be administered via a closed administration system in one-two aliquots (1-2 minutes). The tube position will be confirmed by auscultation. During surfactant administration, infants will be manually ventilated to facilitate surfactant distribution. If necessary, mechanical ventilation with a peak inspiratory pressure (PIP) of 20-22 cmH2O, a Positive End-Expiratory Pressure (PEEP) of 5-6 cmH2O and a respiratory rate of 30-40 breaths/min will be subsequently started to achieve a VT of 4-6 ml/kg and/or to maintain the transcutaneous partial carbon dioxide pressure (TcPCO2) between 40 and 60 mmHg (5.3 and 8.0 kPa).

After surfactant administration, the babies of both groups will be extubated within 30 minutes (if satisfactory respiratory drive is present) and will receive nasal CPAP (6-8 cmH2O) (20). In case of insufficient respiratory drive, CDP (in the babies of IN-REC-SUR-E arm) or PIP (in the IN-SUR-E arm) will be reduced until spontaneous respiratory activity is restored. Maintaining a FiO2 < 0.30 to obtain SpO2 values in the desired range (87-94 %) will drive the eventual reduction in the level of CPAP in the following days. The decision as to whether to begin Bi-level Positive Airway Pressure (BiPAP) or nasal-Intermittent Mandatory Ventilation (N-IMV) to prevent the need for re-intubation in infants of both groups will be up to the neonatologist on duty, and will be considered in the final analysis.

Infants of both groups can receive a subsequent dose of surfactant (100 mg/kg of poractant alfa) using the same method (INSURE or INRECSURE) if they meet the CPAP failure criteria again during the following 12 to 24 hours.

Data collection All collected data can be obtained from the clinical records. They will be reported in electronic data sheets designed for this study.

Statistical analysis The primary efficacy analysis will be conducted on an intention to treat basis. Clinical characteristics of infants in the "IN-REC-SUR-E" and "IN-SUR-E" groups will be described using mean values and standard deviation, median value and range, or rate and percentage. Univariate statistical analysis will be performed using the Student "t" test for parametric continuous variables, the Wilcoxon rank-sum test for non-parametric continuous variables, and Fisher's exact test for categorical variables. A p <0.05 will be considered statistically significant. Then, "IN-REC-SUR-E" treatment and clinical characteristics which are most likely associated with the need for mechanical ventilation (gestational age, birth weight, antenatal steroids, CRIB score) will be included in multiple logistic regression analysis to assess their independent role in predicting "IN-REC-SUR-E" success or failure. Effect estimates will be expressed as relative risk (RR) with profile likelihood-based 95 % confidence limits.

An interim analysis is planned when 50 infants will be enrolled in each arm. Duration of study: 1 year

QUALITY CONTROL AND QUALITY ASSURANCE PROCEDURES Compliance to protocol Compliance will be defined as full adherence to protocol. Compliance with the protocol will be ensured by a number of procedures as described below.

Site set-up Local principal investigators are required to participate in preparatory meetings in which details of study protocol, data collection, "IN-REC-SUR-E" and "IN-SUR-E" procedures will be accurately discussed. All centers will receive detailed written instruction on web based data recording, and, to solve possible difficulties, it will be possible to contact the Clinical Trials Coordinating Center. Moreover, it has been ascertained that "IN-REC-SUR-E" procedure is followed similarly in all participating centers.