Cardiorespiratory Effects of "Higher" Versus "Equivalent" CPAP Upon Extubation From High EAP in Preterm Infants

Overview

The aim of this study is to compare the cardiovascular and respiratory effects of "higher" versus "equivalent" CPAP pressures post-extubation from high endotracheal airway pressures (EAP), defined as at least 8 cm H2O (water), in the form of a randomized controlled cross-over trial. Endotracheal airway pressure (EAP) will be defined as mean airway pressure (MAP) \[if on high frequency ventilation\] or positive end-expiratory pressure (PEEP) \[if on conventional ventilation\] at time of extubation. Participants will be randomized to "higher" CPAP group (CPAP level 2cm H2O higher than the extubation EAP) or "equivalent" CPAP group (CPAP level equal to the extubation EAP) before undergoing crossover to the other arm. We hypothesize that "higher" CPAP levels, when compared to "equivalent" CPAP levels, do not adversely impact the cardiorespiratory status when a patient is extubated from high EAP.

Extubation readiness of the enrolled infants will be determined solely by and at the discretion of the medical team. All enrolled infants will be checked to re-confirm eligibility prior to extubation. Those enrolled infants who are ventilated on EMV (endotracheal mechanical ventilation) with an airway pressure of 8-11 cm H2O at the time when they are deemed extubation-ready by the team will be eligible for randomization. Once eligibility for randomization is assessed, the study coordinator will notify the research team who will immediately perform a bedside functional echocardiography to assess cardiac output and PDA (patent ductus arteriosus) status. In addition, the lung compliance (as measured by the ventilator) will be recorded. If a PDA exists and is found to be hemodynamically significant, then the infant meets one of the exclusion criteria and will be ineligible for randomization. Once eligibility is confirmed, infants will be randomized using sequentially numbered sealed opaque envelopes. The sequence of the randomization will be pre-determined using a computer generated algorithm, and sealed envelopes will be created by study coordinator. Once randomized, the infants will be extubated to the "higher" CPAP group (CPAP level 2cm H2O higher than extubation EAP) or "equivalent" CPAP group (CPAP level equal to the extubation EAP) based on their allocation. After ensuring that the infants are stable for one hour (based on pre-defined clinical instability criteria) cardiac output will be measured using bedside functional echocardiography by members of the research team blinded to the allocation. To ensure blinding the research coordinator will cover the relevant digital display of the ventilator/CPAP machine (with opaque craft paper and tape) immediately prior to the echocardiography. Other aforementioned outcomes will be recorded by the blinded investigator using standardized data collection forms. Once all outcome data are collected, the infants will cross-over to the opposite arm of the trial and a similar assessment protocol will be followed after one hour. The study protocol will be considered completed when the second set of measurements is obtained and further respiratory management will be guided by the medical team. SAFETY ASSURANCE At any point during the study, emergence of any one of the clinical instability criteria will prompt the nursing staff to notify the medical team who would immediately assess the infant. If the infant shows signs of clinical instability the medical team will evaluate the infants' clinical condition as per a pre-defined checklist. When all the troubleshooting points mentioned in the checklist are addressed by the medical team and the infant is deemed clinically unstable, the infant would be immediately removed from the study protocol and parents of the subject will be notified. To ensure that no other factor affects the hemodynamic status of the infants during the study, the total fluid intake would remain the same and no caffeine citrate would be administered during the period of pre and post extubation assessment of cardiac output.