We aimed at evaluating pressure transmission and stability during nonsynchronized neonatal nasal intermittent positive pressure ventilation (NIPPV) delivered using five mechanical ventilators and three nasal interfaces. An artificial nose-throat model was connected to a mechanical analog of the infant respiratory system and a breath generator. Ventilation was administrated via a nasal mask (NM), short bi-nasal prongs (SBN), or RAM® cannula. We applied positive endexpiratory pressures (PEEP) of 5 and 10 cmH 2 O, inspiratory pressures (PIP) of 15 and 30 cmH 2 O, inspiratory times of 0.23, 0.42, and 0.57 s. Measurements were performed with leaks of 0, 1.5, and 4 L/min. The pressure was measured at the airways opening (P AW ) and the glottis (P GL ). The difference between set and delivered pressures (P AW ) was less than ±1 cmH 2 O for all ventilators. We documented a significant difference between P AW and P GL in the presence of leaks. With 4 L/min leaks, PEEP dropped by 43%, 49%, and 63% with NM, SBP, and RAM® cannula, respectively; PIP dropped by 58%, 64%, and 74%. On average, the SD of PEEP fluctuations was ±0.60 and ±2.50 cmH 2 O for P AW and P GL ; the breath-by-breath SD of PIP was ±0.77 and ±2.06 cmH 2 O. During NIPPV, the PIP and PEEP transmission to the glottis is markedly lower than the set values and highly variable. The impact of leaks and nasal interface is much more significant than the differences in ventilators' performance on the efficacy of pressure transmission and stability of nonsynchronized ventilator-generated NIPPV.
Inhaled bronchodilators are often given in preterm infants with evolving or established bronchopulmonary dysplasia. However, it is unclear which patients may benefit from it and when it is the best time to start treatment. The forced oscillation technique (FOT) is a noninvasive method for assessing lung mechanics that proved sensitive to airway obstruction reversibility in children and adults. FOT does not need patient cooperation, which is ideal for infants. Bedside tools for applying FOT in infants during spontaneous breathing and different respiratory support modes are becoming available. This case report illustrates for the first time that FOT has potential value in assessing airway obstruction reversibility in preterm infants, informing which infants may manifest a clinical benefit from the treatment with bronchodilators.
Bronchopulmonary dysplasia (BPD) is the most frequent morbidity of preterm birth and is characterised by abnormal or arrested pulmonary development. Current definitions of BPD suffer from the limitation that they are based on treatment at specific time points [1,2]. Lung mechanics may provide continuous markers of lung disease, independent from unit policies, which could be repeated over time during the evolving phase or follow-up.The forced oscillation technique (FOT) is a non-invasive method for assessing lung mechanics, which does not need patient cooperation. FOT differentiated between preterm and term infants [3] and preterm infants with respiratory distress or evolving BPD [4]. Early FOT measurements improved prognostication of respiratory outcomes compared with clinical data [5,6]. FOT parameters were significantly associated with the severity of neonatal lung disease in prematurely born children [7, 8].We hypothesised that oscillatory mechanics could be functional markers of lung disease. Therefore, we investigated whether FOT parameters at 36 weeks post-menstrual age (PMA) differ between infants with and without BPD and are associated with respiratory support and oxygen therapy duration.We studied infants below 32 weeks gestational age (GA) without congenital abnormalities. Data were part of a prospective study conducted at University Children's Hospital Basel UKBB between October 2016 and March 2018, and a retrospective study conducted at Fondazione Monza e Brianza per il Bambino e la sua Mamma (MBBM) between November 2020 and November 2021. Local ethical committees approved the studies (EKNZ 233/13, 3804/21). Written informed consent was obtained before enrolment in the prospective study.Measurements were performed at 36 weeks PMA or just before discharge home, whichever occurred first. FOT was applied using a mechanical ventilator (Fabian HFOi, Vyaire) that superimposed forced oscillations (amplitude 5 cmH 2 O) on a continuous positive airway pressure (CPAP) of 5 cmH 2 O [5]. The oscillatory frequency was 10 Hz, which showed to be sensitive to changes in lung mechanics while avoiding the interference of spontaneous breathing in preterm infants [6]. Airway opening pressure and flow were recorded for 30 s after 1-min stabilisation and used to compute respiratory system resistance (R rs ) and reactance (X rs ) using a least-squares algorithm. Measurements were performed using a face mask with infants lying supine in their bed with the head in midline position and the neck supported in slight extension according to European Respiratory Society (ERS)/American Thoracic Society (ATS) standards [9]. The correct posture was stabilised by the operator holding the mask. Measurements were made during behaviourally defined quiet sleep approximately 30 min after feeding. Since measurements were performed during CPAP, if there were leaks, they would be detected from the inspection of the flow signal, and the mask position would be adjusted. For each measurement, we manually checked data quality, including the maximu...
Background: Transition from intrauterine to extrauterine life is a critical phase during which several changes occur in cardiovascular system. In clinical practice, it is important to have a method that allows an easy, rapid and precise evaluation of hemodynamic status of a newborn for clinical management. We here propose a rapid, broadly applicable method to monitor cardiovascular function using ultrasonic cardiac output monitoring (USCOM). Methods: We here present data obtained from a cohort of healthy term newborns (n = 43) born by programmed cesarean section at Fondazione MBBM, Ospedale San Gerardo. Measurements were performed during the first hour of life, then at 6 + 2, at 12-24, and 48 h of life. We performed a screening echocardiography to identify a patent duct at 24 h and, if patent, it was repeated at 48 h of life. Results: We show that physiologically, during the first 48 h of life, blood pressure and systemic vascular resistance gradually increase, while there is a concomitant reduction in stroke volume, cardiac output, and cardiac index. The presence of patent ductus arteriosus significantly reduces cardiac output (p = 0.006) and stroke volume (p = 0.023). Furthermore, newborns born at 37 weeks of gestational age display significantly lower cardiac output (p < 0.001), cardiac index (p = 0.045) and stroke volume (p < 0.001) compared to newborns born at 38 and ≥ 39 weeks. Finally, birth-weight (whether adequate, small or large for gestational age) significantly affects blood pressure (p = 0.0349), stroke volume (p < 0.0001), cardiac output (p < 0.0001) and cardiac index (p = 0.0004). In particular, LGA infants display a transient increase in cardiac index, cardiac output and stroke volume up to 24 h of life; showing a different behavior from AGA and SGA infants. Conclusions: Compared to previous studies, we expanded measurements to longer time-points and we analyzed the impact of commonly used clinical variables on hemodynamics during transition phase thus making our data clinically applicable in daily routine. We calculate reference values for each population, which can be of clinical relevance for quick bedside evaluation in neonatal intensive care unit.
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