Description of Lung Ultrasound From Initial Neonatal Transition, The DOLFIN Study

This is a prospective, observational study of spontaneously breathing term and late preterm infants in the delivery room. The primary outcome will be to determine if ultrasound images of the lungs have predictable changes during the first few hours of life. Antenatal consent will be obtained from the parents prior to enrolment after admission to birth suites and initial assessment of the obstetric team or during the final prenatal visit. Consent will only obtained if not in established labour. Ultrasound images will be obtained using the Vividi (GE Healthcare, Wauwatosa, USA). An investigator will perform serial lung ultrasound exams, recordings 3-5 second clips of the right and left lung fields using 2D imaging and M-mode. The lung ultrasound exams will be brief. We will use a timer to limit exams to 2 minutes or less from the time of placing the ultrasound gel on the baby’s skin. Lung ultrasound exams will be performed at 6 time points: less than 10 minutes of life, 10-20 minutes of life, 1 hour of life, 2 hours of life, 4-6 hours of life, and 24-72 hours of life (the final exam targeting the time frame closest to discharge). If the lungs appear to have reached full aeration on two consecutive exams by the ultrasonographer (bilateral presence of A-lines with normal lung sliding), the study will be considered complete and no further images will be obtained. Prior to application to the baby’s skin, the ultrasound gel will warmed by placing it on a clean gauze under the radiant warmer in the patient’s room. After the exam, the ultrasound gel will be removed from the baby’s skin. At the one hour exam, ultrasound images of the will be obtained from the anterior, axillary, and posterior chest of the baby. The purpose of obtaining additional images at the one hour exam will be to test if there is a difference in lung aeration and fluid clearance with the probe positioned at different areas of the chest. In a study of 154 term and late preterm babies, Raimondi and colleagues performed lung ultrasound exams at 1-2 hours of life. Nine percent, 30%, and 61% had type 1, 2, and 3 lung ultrasound findings respectively. Therefore, the one hour exam may be ideal to compare images in different sections of the chest because of the variety of lung aeration grades and less potential to interfere with maternal bonding. The information obtained from the additional images will help standardize the lung ultrasound exam. The one hour exam will be limited to 5 minutes. Lung ultrasound clips will be independently collected by an investigator (DB). Two 2-D clips and 2 images captured with M-mode for each exam will be de-identified, coded, and blindly graded by 3 consultants with expertise in ultrasonography (LF, OK, SR). The degree of lung aeration will be assigned based on the grade of these images at type 1, 2, or 3 using a previously published grading system. In the event of a disagreement among the blinded consultants, if 2/3 consultants agree, that grade will be assigned. If all three consultants assign a different grade, we will review the images openly in a group discussion. We will test inter-rater reliability of characterizing lung ultrasound images as type 1, 2, or 3 by having the three blinded ultra-sonographers independently evaluate each ultrasound clip using a Spearman’s rank-order test. Before the ultrasound exams, we will place a pulse oximetry sensor on the baby’s right hand or wrist to measure the baby’s heart rate and oxygen levels. These measurements can be obtained while the baby is on the mother’s chest or being held by the family. Heart rate and SpO2 will be obtained using either an NM3 Respiratory Profile Monitor (Philips Respironics, The Netherlands) or Radical 7 pulse oximeter (Masimo, California, USA). The heart rate, and SpO2 will be converted from analog to digital signal for statistical analysis. Measurements recorded will be analyzed using Stata Software (StataCorp, College Station, Texas, USA) for statistical analysis. The pulse oximeter will be applied to the baby’s right hand or wrist at each prior to each of the ultrasound examinations and be removed after the ultrasound exam is finished. If available, we will also record the umbilical arterial cord blood gas for analysis. If the investigators observe any concerning findings on lung ultrasound (evidence of pneumothorax or effusion) or pulse oximetry, they will immediately notify the clinical team caring for the baby. Our goal is obtain the desired data without altering the experience of the parents as they introduce a new member to their family and to avoid any interference with the clinicians caring for the baby. The lung ultrasound exams may be performed on the warming bed with the agreement of the clinician caring for the baby. If the clinical team decides that the baby is well enough to be moved from the warming bed to be with the mother, lung ultrasound exams can also with the infant on the mother’s chest or while being held by a family member. If the baby cannot be held by the mother (or other family member) but the baby can be positioned close to the mother, there will be a dedicated research trolley with a warming mattress available to place the baby as close as possible to the mother for lung ultrasound exams. The natural transition of the healthy newborn includes bonding with the mother after birth. The study should not preclude skin to skin contact of babies or breastfeeding with their mothers in the first ten minutes of life. We will review the data collected after enrolling 10 and 50 babies. The purpose will be to review for adverse outcomes, quality of ultrasound images, efficacy of data collection and grading. Specifically, we will monitor the baby’s first temperature collected by the clinical team, the potential of interfering with patient care, review the quality of ultrasound images using different exam techniques and settings (like location of ultrasound probe, gain, and depth), and the inter-relater reliability. The research team has over 10 years of experience studying neonatal transition in the delivery room The measurements obtained from this cohort of babies constitutes an observational study. This data will provide valuable information on the appearance of the lungs on ultrasound from birth through the first day of life and may serve as crucial baseline data for future interventional studies intended to improve respiratory care of newborns. The measurements and images obtained from this cohort of babies constitutes an observational study. The data will provide valuable information on lung ultrasound in the first minutes to hours after birth.