Transcatheter patent ductus arteriosus closure in premature infants requiring high-frequency ventilation.

Transcatheter closure has become a common treatment method for patent ductus arteriosus in premature infants at many centres; however, many remain uncertain about the ability to perform the procedure in the catheterisation laboratory for infants requiring high-frequency ventilation. This study presents our centre's experience following the implementation of neonatal ventilatory guidelines, which resulted in 100% procedural success without any procedural or respiratory adverse events.

Impact of weight adjusted high frequency low tidal volume ventilation and atrial pacing in lesion metrics in high-power short-duration ablation: Results of a pilot study.

INTRODUCTION: Lesion size index (LSI) was introduced with the use of Tacticath™ and as a surrogate of lesion quality. The metric used to achieve the predetermined values involves combined information of contact force (CF), power and radiofrequency time. Rapid atrial pacing (RAP) and high-frequency low-tidal volume ventilation (HFLTV) independently or in combination improve catheter stability and CF and quality of lesions. Data of the impact of body weight adjusted HFLTV ventilation strategy associated with RAP in the lesion metrics still lacking. The study aimed to compare the results of high-power short-duration (HPSD) atrial fibrillation ablation using simultaneous weight adjusted HFLTV and RAP and standard ventilation (SV) protocol. METHODS: Prospective, nonrandomized study with 136 patients undergoing de novo ablation divided into two groups; 70 in RAP (100 ppm) + HFLTV with 4 mL/kg of tidal volume and 25 breaths/min (group A) and 66 patients with SV in intrinsic sinus rhythm (group B). Ablation using 50 W, CF of 5-10 g/10-20 g and 40 mL/minute flow rate on the posterior and anterior left atrial wall, respectively. RESULTS: No procedure-related complications. Group A: Mean LSI points 70 ± 16.5, mean total lower LSI 3.4 ± 0.5, mean total higher LSI 8.2 ± 0.4 and mean total LSI 5.6 ± 0.6. Anterior and posterior wall mean total LSI was 6.0 ± 0.4 and 4.2 ± 0.3, respectively. Mean local impedance drop (LID) points were 118.8 ± 28.4, mean LID index (%) 12.9 ± 1.5, and mean LID < 12% points 55.9 ± 23.8. Anterior and posterior wall mean total LID index were 13.6 ± 2.0 and 11.9 ± 1.7, respectively. Recurrence in 11 (15.7%) patients. Group B: Mean LSI points 56 ± 2.7, mean total lower LSI 2.9 ± 0.7, mean total higher LSI 6.9 ± 0.9, and mean total LSI 4.8 ± 0.8. Anterior and posterior wall mean total LSI was 5.1 ± 0.3 and 3.5 ± 0.5, respectively. Mean LID points were 111.4 ± 21.5, mean LID index (%) 11.4 ± 1.2, and mean LID < 12% points 54.9 ± 25.2. Anterior and posterior wall mean total LID index were 11.8 ± 1.9 and 10.3 ± 1.7, respectively. Recurrence in 14 (21.2%) patients. Mean follow up was 15.2 ± 4.4 months. CONCLUSION: Weight adjusted HFLTV ventilation with RAP HPSD ablation produced lower recurrence rate and better LSI and LID parameters in comparison to SV and intrinsic sinus rhythm.

Impact on cerebral hemodynamics of the use of volume guarantee combined with high frequency oscillatory ventilation in a neonatal animal respiratory distress model.

High-frequency oscillatory ventilation (HFOV) is an alternative to conventional mechanical ventilation (CMV). Recently, the use of volume guarantee (VG) combined with HFOV has been suggested as a safe strategy capable of reducing the damage induced by ventilation in immature lungs. However, the possible impact of this new ventilation technique on cerebral hemodynamics is unknown. To evaluate the cerebral hemodynamics effect of HFOV combined with VG in an experimental animal model of neonatal respiratory distress syndrome (RDS) due to surfactant deficiency compared with HFOV and CMV+VG (control group). Eighteen newborn piglets were randomized, before and after the induction of RDS by bronchoalveolar lavage, into 3 mechanical ventilation groups: CMV, HFOV and HFOV with VG. Changes in cerebral oxygen transport and consumption and cerebral blood flow were analyzed by non-invasive regional cerebral oxygen saturation (CrSO2), jugular venous saturation (SjO2), the calculated cerebral oxygen extraction fraction (COEF), the calculated cerebral fractional tissue oxygen extraction (cFTOE) and direct measurement of carotid artery flow. To analyze the temporal evolution of these variables, a mixed-effects linear regression model was constructed. After randomization, the following statistically significant results were found in every group: a drop in carotid artery flow: at a rate of -1.7 mL/kg/min (95% CI: -2.5 to -0.81; p < 0.001), CrSO2: at a rate of -6.2% (95% CI: -7.9 to -4.4; p < 0.001) and SjO2: at a rate of -20% (95% CI: -26 to -15; p < 0.001), accompanied by an increase in COEF: at a rate of 20% (95% CI: 15 to 26; p < 0.001) and cFTOE: at a rate of 0.07 (95% CI: 0.05 to 0.08; p < 0.001) in all groups. No statistically significant differences were found between the HFOV groups. CONCLUSION: No differences were observed at cerebral hemodynamic between respiratory assistance in HFOV with and without VG, being the latter ventilatory strategy equally safe. WHAT IS KNOWN: • Preterm have a situation of fragility of cerebral perfusion wich means that any mechanical ventilation strategy can have a significant influence. High-frequency oscillatory ventilation (HFOV) is an alternative to conventional mechanical ventilation (CMV). Recently, the use of volume guarantee (VG) combined with HFOV has been suggested as a safe strategy capable of reducing the damage induced by ventilation in immature lungs. Several studies have compared CMV and HFOV and their effects at hemodynamic level. It is known that the use of high mean airway pressure in HFOV can cause an increase in pulmonary vascular resistance with a decrease in thoracic venous return. WHAT IS NEW: • The possible impact of VAFO + VG on cerebral hemodynamics is unknown. Due the lack of studies and the existing controversy, we have carried out this research project in an experimental animal model with the aim of evaluating the cerebral hemodynamic repercussion of the use of VG in HFOV compared to the classic strategy without VG.

Receipt of high-frequency ventilation is associated with acute kidney injury in very preterm neonates.

BACKGROUND: High-frequency ventilation (HFV) is frequently used in critically ill preterm neonates. We aimed to determine the incidence of acute kidney injury (AKI) in neonates less than 29 weeks gestation who received HFV in the first week of life and to determine if the rates of AKI differed in those who received other forms of respiratory support. METHODS: This retrospective cohort study of 24 international, level III/IV neonatal intensive care units (NICUs) included neonates less than 29 weeks gestation from the AWAKEN study database. Exclusion criteria included the following: no intravenous fluids ≥ 48 h, admission ≥ 14 days of life, congenital heart disease requiring surgical repair at < 7 days of life, lethal chromosomal anomaly, death within 48 h, severe congenital kidney abnormalities, inability to determine AKI status, insufficient data on ventilation, and when the diagnosis of early AKI was unable to be made. Subjects were grouped into three groups based on ventilation modes (CPAP/no ventilation, conventional ventilation, and HFV). RESULTS: The incidence of AKI was highest in the CPAP/no ventilation group, followed by HFV, followed by conventional ventilation (CPAP/no ventilation 48.5% vs. HFV 42.6% vs. conventional ventilation 28.4% (p = 0.009). An increased risk for AKI was found for those on HFV compared to CPAP/no ventilation (HR = 2.65; 95% CI:1.22-5.73). CONCLUSIONS: HFV is associated with AKI in the first week of life. Neonates on HFV should be screened for AKI. The reasons for this association are not clear. Further studies should evaluate the relationship between ventilator strategies and AKI in premature neonates. A higher resolution version of the Graphical abstract is available as Supplementary information.

Non-invasive ventilation in neonates: a review of current literature.

Moving from an era of invasive ventilation to that of non-invasive respiratory support, various modalities have emerged resulting in improved neonatal outcomes. Respiratory distress is the commonest problem seen both in preterm and term neonates, and the use of appropriate respiratory support could be lifesaving. This article reviews the currently available non-invasive ventilation (NIV) strategies in neonates including nasal continuous positive airway pressure, nasal intermittent positive pressure ventilation (NIPPV), bi-level CPAP, heated humidified high flow nasal cannula, nasal high-frequency ventilation (NHFV) and non-invasive neutrally adjusted ventilatory assist (NIV-NAVA). Though multiple systematic reviews and meta-analyses have indicated the superiority of synchronized NIPPV over the other forms of non-invasive respiratory support in neonates, there is no single NIV modality that universally suits all. Hence, the choice of NIV for a neonate should be individualized based on its efficacy, the disease pathology, resource settings, the clinician's familiarity and parental values. Future studies should evaluate emerging modalities such as NIV-NAVA and NHFV in the respiratory management of neonates as the evidence pertaining to these is insufficient.

Estimación de Distensibilidad Dinámica Toraco-pulmonar en Modelos Neonatales de Ventilación Mecánica de Alta Frecuencia / Estimation of dynamic thoracopulmonary compliance in neonatal high-frequency mechanical ventilation models

Introducción. La ventilación de alta frecuencia (VAF) es utilizada en pacientes graves neonatales con un uso cercano al 10% del total de usuarios en ventilación mecánica (VM). Actualmente estos equipos miden volumen corriente de manera precisa, continua y rutinaria, sin embargo no hay estimaciones del comportamiento mecánico del sistema respiratorio del usuario, como lo es la distensibilidad toracopulmonar, durante el ciclo ventilatorio que sean reportadas por las pantallas de los equipos. Objetivo. Estimar distensibilidad dinámica toracopulmonar en modelos neonatales de VAF. Métodos. Estudio cuantitativo, observacional, descriptivo, y "wench work", donde se midió distensibilidad en VM convencional y volumen corriente (Vt) en VAF con equipo Acutronics Fabian® por 4 evaluadores independientes, en 5 tipos de pulmón de ensayo y bajo diferentes escenarios de parámetros de VAF con ajustes de presión media de la vía aérea (PMVA), amplitud, frecuencia respiratoria, tiempo inspiratorio, volumen garantizado, y tipo de circuito. Mediante suavización de regresiones locales por estimación mínima cuadrática (LOWESS) y análisis de regresión multivariada se obtuvieron los valores asociados a distensibilidad, con los que se construyeron ecuaciones de estimación de distensibilidad en VAF. Resultados. Se realizaron en total 46080 mediciones, con correlación intra e interevaluador > 0.99. La distensibilidad mediana (percentil 25; 75) de los 5 modelos pulmonares fue de 0.455 (0.3; 0.98). Se asociaron a distensibilidad, mediante modelos de regresión lineal múltiple de manera significativa, todas las variables evaluadas, salvo PMVA. Se establecieron asociaciones multivariantes crudas (R2=.311), de distensibilidad predicha por LOWESS (R2=.744) y distensibilidad predicha y variables independientes predichas por regresión lineal simple (R2=.973). Conclusiones. La distensibilidad en VAF esta determinada en pulmones de ensayos por los parámetros programados de: tipo de circuito, uso de volumen garantizado, tiempo inspiratorio, frecuencia respiratoria y amplitud, además del Vt medido. Se reporta ecuación explicativa de distensibilidad en VAF.

Background. Background: High frequency mechanical ventilation (HFV) is used in severe neonatal subjects nearly 10% of total mechanically ventilated (MV) users. Currently, this MV's mode allow to measure tidal volumen in an accurately, continuous and routinarie way in HFV, however there are non estimation to assess mechanical behavior of respiratory system during ventilatory cycle, like thoraco-pulmonary compliance, who be report in the equipment display. Objetive. To estimate thoraco-pulmonary compliance in artificial neonatal lung models in HFV. Methods. Quantitative, observational, descriptive, and wench work study, where distensibility was measured in conventional MV and tidal volume (TV) in HFV with Acutronics Fabian® equipment by 4 independent evaluators, in 5 types of test lung and under different scenarios of HFV parameters with adjustments of mean airway pressure (MAP), amplitude, respiratory rate, inspiratory time, guaranteed volume, and type of circuit. By smoothing local regressions by least quadratic estimation (LOWESS) and multivariate regression analysis, the values associated with distensibility were obtained, with this measures, equations for estimating compliance in VAF were constructed. Results. A total of 46080 measurements were made, with intra and inter-evaluator correlation coefficent > 0.99. The median compliance (25th percentile; 75) of the 5 lung models was 0.455 (0.3; 0.98). All variables evaluated, except MAP, were associated with compliance, by means of multiple linear regression models. Crude multivariate associations (R2 = .311), predicted compliance by LOWESS (R2 = .744) and predicted compliance and independent variables predicted by simple linear regression (R2 = .973) were established to estimate thoraco-pulmonary compliance. Conclusions. Compliance in VAF is determined in test lungs by the programmed parameters of: type of circuit, use of guaranteed volume, inspiratory time, respiratory frequency and amplitude, in addition to the measured Vt. An explanatory equation for distensibility in VAF is reported.

Venovenous extracorporeal membrane oxygenation for respiratory failure refractory to high frequency percussive ventilation.

BACKGROUND: High frequency percussive ventilation (HFPV) has demonstrated improvements in gas exchange, but not in clinical outcomes. OBJECTIVES: We utilize HFPV in patients failing conventional ventilation (CV), with rescue venovenous extracorporeal membrane oxygenation (VV ECMO) reserved for failure of HFPV, and we describe our experience with such a strategy. METHODS: All adult patients (age >18 years) placed on HFPV for failure of CV at a single institution over a 10-year period were included. Those maintained on HFPV were compared to those that failed HFPV and required VV ECMO. Survival was compared to expected survival after upfront VV ECMO as estimated by VV ECMO risk prediction models. RESULTS: Sixty-four patients were placed on HFPV for failure of CV over a 10-year period. After HFPV initiation, the P/F ratio rose from 76mmHg to 153.3mmHg in the 69 % of patients successfully maintained on HFPV. The P/F ratio only rose from 60.3mmHg to 67mmHg in the other 31 % of patients, and they underwent rescue ECMO with the P/F ratio rising to 261.6mmHg. The P/F ratio continued to improve in HFPV patients, while it declined in ECMO patients, such that at 24 h, the P/F ratio was greater in HFPV patients. The strongest independent predictor of failure of HFPV requiring rescue VV ECMO was a lower pO2 (p = .055). Overall in-hospital survival (59.4 %) was similar to that expected with upfront ECMO (RESP score: 57 %). CONCLUSIONS: HFPV demonstrated significant and sustained improvements in gas exchange and may obviate the need for ECMO and its associated complications.

Comparison between weight-adjusted, high-frequency, low-tidal-volume ventilation and atrial pacing with normal ventilation in high-power, short-duration atrial fibrillation ablation: Results of a pilot study.

Background: Better contact force (CF) and catheter stability (CS) during atrial fibrillation (AF) ablation are associated with higher success rate. Changes in CF and CS are observed during respiratory movements and cardiac contraction. Previous studies have suggested that rapid atrial pacing (RAP) and high-frequency, low-tidal-volume ventilation (HFLTV) independently or in combination improve CS and CF and quality of lesions. Data from a body weight-adjusted HFLTV strategy associated with RAP in AF high-power, short-duration (HPSD) ablation are still lacking. Objective: This study aimed to compare the results of HPSD AF ablation using simultaneous weight-adjusted HFLTV and RAP and standard ventilation (SV) protocol. Methods: This was a prospective, nonrandomized study with 136 patients undergoing de novo ablation were divided into 2 groups: 70 in RAP (100 ppm) + HFLTV with 4 mL/kg of tidal volume and 25 breaths/min (group A) and 66 patients with SV in intrinsic sinus rhythm (group B). The ablation used 50 W, CF of 5 to 10 g and 10 to 20 g, and 40 mL/min flow rate on the posterior and anterior left atrial walls, respectively. Results: There were no procedure-related complications. In group A, left atrial and total ablation times were 53.5 ± 8.3 minutes and 67.4 ± 10.1 minutes, respectively. Radiofrequency time was 19.7 ± 5.7 minutes, radioscopy time was 3.4 ± 1.8 minutes, 62 (88.6%) patients had first-pass isolation, 23 (33.3%) patients had elevation of luminal esophageal temperature, and 7 (10%) patients had recurrence. In group B, left atrial time was 56.7 ± 10.8 minutes, total ablation time was 72.4 ± 11.5 minutes, radiofrequency time was 22.4 ± 6.2 minutes, radioscopy time was 3.6 ± 3 minutes, 58 (87.9%) patients had first-pass isolation, and 20 (30.3%) patients had luminal esophageal temperature elevation. Conclusion: Weight-adjusted HFLTV with RAP in comparison with SV and intrinsic sinus rhythm in HPSD ablation is safe with no CO2 retention. The approach produced significantly reduced radiofrequency, left atrial, and total ablation times and better CF and local impedance drop indexes.

Regular lung recruitment maneuvers during high-frequency oscillatory ventilation in extremely preterm infants: a randomized controlled trial.

BACKGROUND: Lung recruitment maneuvers (LRMs) improve lung volume at initiation of high-frequency oscillatory ventilation (HFOV), but it is unclear when to repeat LRMs. We evaluated the efficiency of scheduled LRMs. METHODS: In a randomized controlled trial, extremely preterm infants on HFOV received either LRMs at 12-hour intervals and when clinically indicated (intervention) or only when clinically indicated (control). The primary outcome was the cumulative oxygen saturation index (OSI) over HFOV time, limited to 7 days. Additionally, LRMs were analyzed with respect to OSI improvement. RESULTS: Fifteen infants were included in each group. The mean (SD) postmenstrual age and weight at HFOV start were 23 + 6 (0 + 5) weeks and 650 (115) g in the intervention group and 24 + 4 (0 + 6) weeks (p = 0.03) and 615 (95) g (p = 0.38) in the control group. The mean (SD) cumulative OSI amounted to 4.95 (1.72) in the intervention versus 5.30 (2.08) in the control group (p = 0.61). The mean (SD) number of LRMs in 12 h was 1.3 (0.2) in the intervention versus 1.1 (0.5) in the control group (p = 0.13). Performing LRM when FiO2 > 0.6 resulted in a mean OSI reduction of 3.6. CONCLUSION: Regular versus clinically indicated LRMs were performed with equal frequency in preterm infants during HFOV, and consequently, no difference in lung volume was observed. LRMs seem to be most efficient at high FiO2. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT04289324 (28/02/2020).

Lung protection strategy with high-frequency oscillatory ventilation improves respiratory outcomes at two years in preterm respiratory distress syndrome: a before and after, quality improvement study.

INTRODUCTION: Bronchopulmonary dysplasia (BPD) remains one of the major challenges of extreme prematurity. High-frequency oscillatory ventilation (HFOV) with volume guarantee (HFOV-VG) can be used as an early-rescue ventilation to protect developing lungs. However, the studies exploring the impact of this ventilatory strategy on neonatal respiratory morbidity are very limited. This study aimed at documenting the improvement in respiratory outcomes in mechanically ventilated preterm newborns, after the implementation of a new mechanical ventilation respiratory bundle. METHODS: A prospective, quality improvement study was conducted between January 2012 and December 2018 in a third level NICU in Madrid, Spain. Infants born <32 weeks of gestation with severe respiratory distress syndrome (RDS) and requiring invasive mechanical ventilation were included. The intervention consisted of a new ventilation respiratory care bundle, with HFOV as early rescue therapy using low high-frequency tidal volumes (Vthf) and higher frequencies (15-20 Hz). Criteria for HFOV start were impaired oxygenation or ventilation on conventional ventilation, or peak inspiratory pressures >15 cmH2O. Two cohorts of mechanically ventilated patients were compared, cohort 1 (2012-2013, baseline period) and cohort 2 (2016-2018, after implementation of the new bundle). Clinical outcomes at 36 weeks and 2 years of postmenstrual age were compared between the groups. RESULTS: A total of 216 patients were included, the median gestational age was 26 weeks (IQR 25-28) and median birth weight was 895 g (IQR 720-1160). There were no significant differences in survival between the groups, but patients with the protective ventilation strategy (cohort 2) had higher survival without BPD 2-3 (OR 2.93, 95%CI 1.41-6.05). At 2 years of postmenstrual age, patients in cohort 2 also had a higher survival free of baseline respiratory treatment and hospital respiratory admissions than the control group (adjusted OR 2.33, 95%CI 1.10-4.93, p=.03). The results did not suggest significant differences in neurologic development. CONCLUSIONS: In extreme premature related severe respiratory failure, the use of a lung protective HFOV-VG strategy was proven to be a useful quality improvement intervention in our unit, leading to better pulmonary outcomes at 36 weeks and additional improved respiratory prognosis at two years of age.

2021 Year in Review: Pediatric Mechanical Ventilation.

Mechanical ventilation is commonly used in the pediatric intensive care unit. This paper reviews studies of pediatric mechanical ventilation published in 2021. Topics include physiology, ventilator modes, alarms, disease states, airway suctioning, ventilator liberation, prolonged ventilation, and others.

The Physiological Basis of High-Frequency Oscillatory Ventilation and Current Evidence in Adults and Children: A Narrative Review.

High-frequency oscillatory ventilation (HFOV) is a type of invasive mechanical ventilation that employs supra-physiologic respiratory rates and low tidal volumes (VT) that approximate the anatomic deadspace. During HFOV, mean airway pressure is set and gas is then displaced towards and away from the patient through a piston. Carbon dioxide (CO2) is cleared based on the power (amplitude) setting and frequency, with lower frequencies resulting in higher VT and CO2 clearance. Airway pressure amplitude is significantly attenuated throughout the respiratory system and mechanical strain and stress on the alveoli are theoretically minimized. HFOV has been purported as a form of lung protective ventilation that minimizes volutrauma, atelectrauma, and biotrauma. Following two large randomized controlled trials showing no benefit and harm, respectively, HFOV has largely been abandoned in adults with ARDS. A multi-center clinical trial in children is ongoing. This article aims to review the physiologic rationale for the use of HFOV in patients with acute respiratory failure, summarize relevant bench and animal models, and discuss the potential use of HFOV as a primary and rescue mode in adults and children with severe respiratory failure.

Feasibility, Safety, and Short-Term Outcomes of Transcatheter Patent Ductus Arteriosus Closure in Premature Infants on High-Frequency Jet Ventilation.

Background Prolonged exposure to a hemodynamically significant patent ductus arteriosus (PDA) is associated with major morbidity, particularly in infants born at <27 weeks' gestation. High-frequency jet ventilation (HFJV) is a standard of care at our center. There are no data about transcatheter PDA closure while on HFJV. The aim of this study was to assess the feasibility, safety, and outcomes of HFJV during transcatheter PDA closure. Methods and Results This is a retrospective cohort study of premature infants undergoing transcatheter device closure on HFJV. The primary outcome was successful device placement. Secondary outcomes included procedure time, fluoroscopy time and dose, time off unit, device complications, need for escalation in respiratory support, and 7-day survival. Subgroup comparative evaluation of patients managed with HFJV versus a small cohort of patients managed with conventional mechanical ventilation was performed. Thirty-eight patients were included in the study. Median age and median weight at PDA device closure for the HFJV cohort were 32 days (interquartile range, 25.25-42.0 days) and 1115 g (interquartile range, 885-1310 g), respectively. There was successful device placement in 100% of patients. There were no device complications noted. The time off unit and the procedure time were not significantly different between the HFJV group and the conventional ventilation group. Infants managed by HFJV had shorter median fluoroscopy times (4.5 versus 6.1 minutes; P<0.05) and no increased risk of adverse respiratory outcomes. Conclusions Transcatheter PDA closure in premature infants on HFJV is a safe and effective approach that does not compromise device placement success rate and does not lead to secondary complications.

Gas Exchange Mechanism of High Frequency Ventilation: A Brief Narrative Review and Prospect.

The high frequency ventilation (HFV) can well support the breathing of respiratory patient with 20%-40% of normal tidal volume. Now as a therapy of rescue ventilation when conversional ventilation failed, the HFV has been applied in the treatments of severe patients with acute respiratory failure (ARF), acute respiratory distress syndrome (ARDS), etc. However, the gas exchange mechanism (GEM) of HFV is still not fully understood by researchers. In this paper, the GEM of HFV is reviewed to track the studies in last decades and prospect for the next likely studies. And inspired by previous studies, the GEM of HFV is suggested to be continually developed with various hypotheses which will be testified in simulation, experiment and clinic trail. One of the significant measures is to study the GEM of HFV under the cross-disciplinary integration of medicine and engineering. Fully understanding the GEM can theoretically support and expand the applications of HFV, and is helpful in investigating the potential indications and contraindications of HFV.

Definitive Closure of the Patent Ductus Arteriosus in Preterm Infants and Subsequent Short-Term Respiratory Outcomes.

A persistent patent ductus arteriosus (PDA) can have significant clinical consequences in preterm infants, depending on the degree of left-to-right shunting, its impact on cardiac performance, and associated perinatal risk factors that can mitigate or exacerbate the shunt. Although the best management strategy remains contentious, PDAs that have contraindications to, or have failed medical management have historically undergone surgical ligation. Recently smaller occluder devices and delivery systems have allowed for minimally invasive closure in the catheterization laboratory even in extremely premature infants. The present review summarizes the pathophysiologic manifestations, treatment options and management of hemodynamically significant PDA in preterm infants. Additionally, we review the available literature surrounding the respiratory support and outcomes of preterm infants following definitive PDA closure.

Efficacy and safety of noninvasive high-frequency oscillatory ventilation in the treatment of respiratory failure in premature infants / 中国基层医药

Objective:To investigate the efficacy and safety of noninvasive high-frequency oscillatory ventilation in the treatment of respiratory failure in premature infants.Methods:Sixty-one premature infants with respiratory failure who received treatment in Neonatal Intensive Care Unit, Wenzhou Central Hospital from June 2019 to June 2020 were included in this study. They were randomly assigned to undergo either noninvasive high-frequency oscillatory ventilation (observation group, n = 31) or transnasal continuous positive airway pressure ventilation (control group, n = 31). Blood gas indicators, including pH value, oxygen partial pressure (PaO 2), partial pressure of carbon dioxide (PaCO 2), oxygenation index (OI), and respiratory index (RI), were determined before ventilation and 2, 8, 12, and 24 hours after ventilation. At the same time, the incidence of complications post-ventilation, including intracranial hemorrhage, bronchopulmonary dysplasia, air leakage, nasal crush injury, retinopathy of prematurity, abdominal distension, and necrotizing enterocolitis, was recorded in each group. Results:There were no significant differences in pH value, PaO 2, PaCO 2, OI, and RI pre-ventilation between observation and control groups ( t = 0.58, 0.64, 0.85, 0.43, 0.70, all P > 0.05). pH value, PaO 2, and OI measured 2, 8, 12 and 24 hours post-ventilation were significantly higher in the observation group than in the control group (pH value: t2 h = 3.20, t8 h = 4.81, t12 h = 6.39, t24 h = 5.22; PaO 2value:t2 h = 5.80, t8 h = 6.31, t12 h = 7.55, t24 h = 6.97; OI value: t2 h = 6.38, t8 h = 8.37, t12 h = 11.30, t24 h = 9.61). PaCO 2 and RI values were significantly lower in the observation group than in the control group (PaCO 2value:t2 h = 4.29, t8 h = 5.09, t12 h = 6.83, t24 h = 8.30; RI value: t2 h = 3.26, t8 h = 5.81, t12 h = 7.36、 t24 h = 6.54) (all P < 0.05). The incidence of complications was significantly lower in the observation group than in the control group [25.81% (8/31) vs. 46.67% (14/30), χ2 = 8.75, P < 0.05]. Conclusion:Compared with transnasal continuous positive airway pressure ventilation, noninvasive high-frequency oscillatory ventilation leads to better ventilation performance and a greater oxygenation ability, exhibits stronger effects on CO 2 clearance and acidosis correction, and has fewer complications in premature infants with respiratory failure. Therefore, noninvasive high-frequency oscillatory ventilation is suitable for clinical application.

Unsuccessful and Successful Clinical Trials in Acute Respiratory Distress Syndrome: Addressing Physiology-Based Gaps.

The acute respiratory distress syndrome (ARDS) is a severe form of acute hypoxemic respiratory failure caused by an insult to the alveolar-capillary membrane, resulting in a marked reduction of aerated alveoli, increased vascular permeability and subsequent interstitial and alveolar pulmonary edema, reduced lung compliance, increase of physiological dead space, and hypoxemia. Most ARDS patients improve their systemic oxygenation, as assessed by the ratio between arterial partial pressure of oxygen and inspired oxygen fraction, with conventional intensive care and the application of moderate-to-high levels of positive end-expiratory pressure. However, in some patients hypoxemia persisted because the lungs are markedly injured, remaining unresponsive to increasing the inspiratory fraction of oxygen and positive end-expiratory pressure. For decades, mechanical ventilation was the only standard support technique to provide acceptable oxygenation and carbon dioxide removal. Mechanical ventilation provides time for the specific therapy to reverse the disease-causing lung injury and for the recovery of the respiratory function. The adverse effects of mechanical ventilation are direct consequences of the changes in pulmonary airway pressures and intrathoracic volume changes induced by the repetitive mechanical cycles in a diseased lung. In this article, we review 14 major successful and unsuccessful randomized controlled trials conducted in patients with ARDS on a series of techniques to improve oxygenation and ventilation published since 2010. Those trials tested the effects of adjunctive therapies (neuromuscular blocking agents, prone positioning), methods for selecting the optimum positive end-expiratory pressure (after recruitment maneuvers, or guided by esophageal pressure), high-frequency oscillatory ventilation, extracorporeal oxygenation, and pharmacologic immune modulators of the pulmonary and systemic inflammatory responses in patients affected by ARDS. We will briefly comment physiology-based gaps of negative trials and highlight the possible needs to address in future clinical trials in ARDS.

High-frequency Ventilation.

High-frequency ventilation (HFV) is an alternative to conventional mechanical ventilation, with theoretic benefits of less risk of ventilator lung injury and more effectivity in washout CO2. Previous clinical studies have not demonstrated advantages of HFV in preterm infants compared with conventional ventilation, so rescue HFV has been used when severe respiratory insufficiency needs aggressive ventilator settings in immature infants. Today it is possible to measure, set directly, and fix tidal volume, which can protect the immature lung from large volumes and fluctuations of the tidal volume. This strategy can be used in preterm infants with respiratory failure needing invasive ventilation.

A narrative review of advanced ventilator modes in the pediatric intensive care unit.

Respiratory failure is a common reason for pediatric intensive care unit admission. The vast majority of children requiring mechanical ventilation can be supported with conventional mechanical ventilation (CMV) but certain cases with refractory hypoxemia or hypercapnia may require more advanced modes of ventilation. This paper discusses what we have learned about the use of advanced ventilator modes [e.g., high-frequency oscillatory ventilation (HFOV), high-frequency percussive ventilation (HFPV), high-frequency jet ventilation (HFJV) airway pressure release ventilation (APRV), and neurally adjusted ventilatory assist (NAVA)] from clinical, animal, and bench studies. The evidence supporting advanced ventilator modes is weak and consists of largely of single center case series, although a few RCTs have been performed. Animal and bench models illustrate the complexities of different modes and the challenges of applying these clinically. Some modes are proprietary to certain ventilators, are expensive, or may only be available at well-resourced centers. Future efforts should include large, multicenter observational, interventional, or adaptive design trials of different rescue modes (e.g., PROSpect trial), evaluate their use during ECMO, and should incorporate assessments through volumetric capnography, electric impedance tomography, and transpulmonary pressure measurements, along with precise reporting of ventilator parameters and physiologic variables.