David Gerald Tingay

High-frequency jet ventilation (HFJV) is a ventilation mode that has been available to treat neonatal respiratory failure for more than 35 years. Compared to high-frequency oscillatory ventilation, HFJV can support ventilation with relatively lower mean airway pressures and longer passive expiration. As such, HFJV is often used to treat complex respiratory conditions such as pulmonary hypoplasia, severe pulmonary interstitial emphysema, congenital lung diseases and heterogenous lung states (such as evolving chronic lung disease), in addition to rescue therapy for primary respiratory failure. Common to all these conditions is the need to match ventilator settings to the pathophysiological mechanical and end-expiratory needs. There is renewed interest in HFJV as a potential lung protective modality, especially in the most developmentally immature lungs. The aim of this review is to provide a clinical practice summary of HFJV and the application in different lung conditions. Impact: High-frequency jet ventilation is most often used in complex neonatal lung conditions such as pulmonary hypoplasia, interstitial emphysema, the most developmentally immature lungs and gas trapping. High-frequency jet ventilation offers theoretical advantages in these conditions compared to other modalities but safe and effective application also requires greater understanding of mode of action. This review aims to provide clinicians with a practical summary of HFJV, specifically an approach to setting HFJV parameters in clinical practice, important clinical considerations and future research priorities to address critical knowledge gaps.

High-frequency jet ventilation (HFJV) is used to manage severe respiratory failure in neonates, especially to manage gas trapping. To our knowledge, the role of HFJV rate on lung volume states and intra-tracheal and thoracic pressures has not been described. The aim of our study was to determine the impact of HFJV rate (HFJV _rate ) on (1) total and regional end-expiratory lung volume (EELV) and (2) intra-thoracic pressure, specifically intra-tracheal pressure ( P _trach ) and oesophageal pressure ( P _oes ) in adult New Zealand white rabbits ( n = 5) prone to gas trapping. After stabilisation on HFJV (Bunnell LifePulse Ventilator; mean (SD) PEEP and HFJV PIP were 5.6 (1.3) cmH ₂ O and 21 (2.6) cmH ₂ O), HFJV _rate between 150 and 900 bpm were randomly applied and regional EELV (electrical impedance tomography), P _trach and P _oes measured with gas exchange parameters. The non-gravity-dependent hemithorax demonstrated greater relative EELV with increasing HFJV _rate , suggesting overdistension at higher rates. Δ P _trach increased linearly from HFJV _rate 150 to 900 bpm and conversely Δ P _oes was more variable, decreased with increasing HFJV _rate . There was a U-shaped relationship between HFJV _rate and PaCO ₂ with best CO ₂ clearance occurring at HFJV _rate 320–400 bpm. Impact: In an animal model susceptible to gas trapping, high-frequency jet ventilation rate influenced volume state with increased carbon dioxide at low and high rates. This is the first study to define the mechanisms by which expiratory time during high-frequency jet ventilation alone can cause and relieve overdistension and atelectasis. Electrical impedance tomography was able to identify optimal lung volume, which may be useful in titrating the best high-frequency jet ventilation rate between 240 and 400 bpm for carbon dioxide clearance.

Objective: To evaluate the frequency and safety of nasal versus oral endotracheal intubation procedures in infants admitted to a neonatal intensive care unit (NICU). Design: Retrospective cohort study. Setting: 29 centres across seven countries from April 2017 to March 2025. Patients: Infants <1 year of age undergoing endotracheal intubation. Main outcome measures: Primary outcome was first course success, with course defined as all intubation attempts without a change in equipment, premedication or route. Secondary outcomes were first attempt success, adverse tracheal intubation-associated events (TIAEs), severe TIAEs and severe desaturations. Adjusted relative risks (aRR) were estimated using Poisson regression accounting for centre, patient, provider and procedural variables. Results: Among 20 350 intubation courses (nasal 1057 (5.2%); oral 19 293 (94.8%)), nasal intubations occurred at 17 of 29 centres, with site-level use ranging from 0% to 99.2%. In fully adjusted models, nasal compared with oral intubation was associated with decreased course success (aRR 0.89; 95% CI 0.84 to 0.94, p<0.001), first attempt success and increased risk for severe desaturation. There were no significant differences in TIAEs. In a post-hoc analysis, these associations were not present at sites where intubations were predominantly performed via nasal route. Conclusions: Nasal intubation may not be the preferred approach for infants in settings where it is infrequently performed but may achieve comparable or improved intubation-related outcomes in centres with established expertise.

Functional chest imaging using electrical impedance tomography (EIT) has experienced an impressive technological development since its invention in the early eighties of the last century. The number of experimental and clinical studies using this technology is continuously rising, and the increasing availability of devices approved for clinical use accelerates and diversifies its applications in patients. EIT is predominantly used in intensive care units but its utilisation in operating theatres, delivery rooms, pulmonary function laboratories and even remote outpatient settings is growing. Chest EIT is mainly applied to determine the regional distribution of pulmonary ventilation, aeration changes, and respiratory system mechanics both during mechanical ventilation and spontaneous breathing, but an increase in the use of chest EIT for imaging lung perfusion and cardiac action has recently been noted. The ongoing innovation of both EIT hardware and software, the new application fields, and the rising number of users of this technology require consensus on EIT terminology and definitions. This secures a common framework for conducting EIT studies, patient examinations and guarantees unified analysis of EIT data, documentation, reporting and comparability of findings. Our article provides a comprehensive consensus document on EIT terminology and definitions generated by EIT experts of the international TRanslational EIT development stuDy group in cooperation with the producers of EIT technology. It not only updates and extends the first consensus EIT terminology published in 2017, but also offers a new taxonomy of EIT measures, systematically based on the quantification of ventilation-related, heartbeat-related, and contrast-enhanced EIT signals. Thanks to its clear structure with tabulated recommended EIT terms, abbreviations, comprehensible explanations, notes, extensive literature sources and parameter calculations, EIT researchers, clinical users and manufacturers may use this document as a reference source of information relevant for chest EIT.

Background: The most effective and safe level of positive end-expiratory pressure (PEEP) during stabilisation at birth of extremely preterm infants is unknown. In observational studies, an initial high PEEP level, then titrated to response (dynamic PEEP strategy), improved clinically relevant outcomes compared with current practice using a static, and lower, PEEP level. The Positive End-Expiratory Pressure Levels during Resuscitation of Preterm Infants at Birth (POLAR) trial will evaluate a novel dynamic PEEP strategy at birth. Methods: In an international multicentre prospective open-label randomised controlled trial, we will randomise extremely preterm infants who require respiratory support from birth to either dynamic PEEP or a static PEEP. The primary outcomes are death or bronchopulmonary dysplasia at 36 weeks’ postmenstrual age. The experimental intervention of a dynamic PEEP strategy commences at 8 cmH ₂ O, but individualised to clinical need to a maximum PEEP 12 cmH ₂ O during stabilisation in the delivery room. The control arm is a standard, static PEEP (5–6 cmH ₂ O). Important short-term respiratory morbidity and potential harm outcomes in the first 10 days after birth are pre-specified secondary outcomes. Trial registration: www.clinicaltrials.gov , Trial Identifier NCT04372953, Registered 4 May 2020. Impact: The most effective and safe level of positive end-expiratory pressure (PEEP) during stabilisation at birth of extremely preterm infants remains unknown. The international multicentre randomised controlled Positive End-Expiratory Pressure Levels during Resuscitation of Preterm Infants at Birth (POLAR) trial is designed to evaluate a novel dynamic PEEP strategy. The POLAR Trial will compare starting at 8 cmH ₂ O PEEP at birth, then titrated between 8 and 12 cmH ₂ O to response, against a static, lower, 6 cmH ₂ O PEEP reflecting current practice. We plan to recruit 906 extremely preterm infants from birth. Reducing death or bronchopulmonary dysplasia (primary outcome) would represent a major advance in neonatal care.

Background: Electrical impedance tomography (EIT) has been proposed as a bedside method of measuring pulmonary blood patterns in neonates. However, EIT’s use has been limited by technical issues including cardiac-motion artefact and ventilation masking the heartbeat-related signals (HRS). This study aims to determine EIT-derived pulmonary blood volume patterns in two distinct biological models. Methods: The HRS were extracted from EIT recordings during Study A: 10 ml saline administered into the right atrium of apnoeic lambs ( n = 6) with cardiac output, and during asystole. Study B: A sustained inflation (aeration without tidal ventilation) during the respiratory transition at birth in preterm lambs ( n = 12). Results: Study A: There was a significant fall in HRS-impedance within lung regions upon administration of saline that was independent of cardiac output ( p < 0.0001, Two-way repeated-measure ANOVA), which was not influenced by cardiac motion ( p = 0.16), suggesting EIT can detect changes to pulmonary arterial bed blood volume. Study B: The amplitude of the HRS decreased linearly during aeration ( R ² = 0.062; linear regression) as a net result of decreased diastolic and increased systolic HRS. Conclusion: EIT demonstrated expected pulmonary blood volume changes in the lung independent of cardiac motion, highlighting EIT’s potential to measure ventilation and pulmonary circulation mismatch in neonates. Impact: EIT may represent a future potential solution to the lack of non-invasive and radiation-free measurements of ventilation and pulmonary perfusion in neonates. Our study showed that EIT can detect changes in thoracic impedance that are independent of ventilation and heart motion within the chest and can delineate pulmonary vascular changes that occur at birth. This suggests EIT could be used to detect blood volume changes in the lungs of neonates in the immediate postnatal period.