Lung recruitment and endotracheal suction in ventilated preterm infants measured with electrical impedance tomography.

AIMS: Although suctioning is a standard airway maintenance procedure, there are significant associated risks, such as loss of lung volume due to high negative suction pressures. This study aims to assess the extent and duration of change in end-expiratory level (EEL) resulting from endotracheal tube (ETT) suction and to examine the relationship between EEL and regional lung ventilation in ventilated preterm infants with respiratory distress syndrome. METHODS: A prospective observational clinical study of the effect of ETT suction on 20 non-muscle-relaxed preterm infants with respiratory distress syndrome (RDS) on conventional mechanical ventilation was conducted in a neonatal intensive care unit. Ventilation distribution was measured with regional impedance amplitudes and EEL using electrical impedance tomography. RESULTS: ETT suction resulted in a significant increase in EEL post-suction (P < 0.01). Regionally, anterior EEL decreased and posterior EEL increased post-suction, suggesting heterogeneity. Tidal volume was significantly lower in volume-guarantee ventilation compared with pressure-controlled ventilation (P = 0.04). CONCLUSIONS: ETT suction in non-muscle-relaxed and ventilated preterm infants with RDS results in significant lung volume increase that is maintained for at least 90 min. Regional differences in distribution of ventilation with ETT suction suggest that the behaviour of the lung is heterogeneous in nature.

Humidified high flow nasal cannulae: current practice in Australasian nurseries, a survey.

AIM: Humidified High Flow Nasal Cannula (HHFNC) has been increasingly adopted as a new means of respiratory support throughout the world. However, evidence to support its safety and efficacy is limited. The aim of the present survey was to determine current practices regarding the usage of HHFNC by neonatologists in Australia and New Zealand. METHODS: Surveys were sent to all 167 neonatologists identified by the list of centres in the Australia and New Zealand Neonatal Network. RESULTS: A total of 157 surveys were sent to valid email addresses: 111 (71%) responded of which 105 (67%) had completed the questionnaire. HHFNC is used in 17 (63%) of neonatal intensive care units in Australia and New Zealand. It is most commonly used to reduce nasal trauma (91%) and provide continuous positive airways pressure (62%). The main perceived benefits of HHFNC were the easier application and care of the infant (86%), and improved tolerance by the baby (84%). Rain out leading to fluid instillation into the upper airway (59%) was the most common problem. CONCLUSION: This survey has provided a snapshot of the practice of HHFNC usage in Australia and New Zealand in 2010 and has revealed that HHFNC use is widespread and that clinical practices are diverse. The majority of neonatologists acknowledge that there is limited evidence to support its efficacy and safety, and would be happy to participate in clinical trials to address how best to deliver HHFNC.

Effect of Treatment of Clinical Seizures vs Electrographic Seizures in Full-Term and Near-Term Neonates: A Randomized Clinical Trial.

Importance: Seizures in the neonatal period are associated with increased mortality and morbidity. Bedside amplitude-integrated electroencephalography (aEEG) has facilitated the detection of electrographic seizures; however, whether these seizures should be treated remains uncertain. Objective: To determine if the active management of electrographic and clinical seizures in encephalopathic term or near-term neonates improves survival free of severe disability at 2 years of age compared with only treating clinically detected seizures. Design, Setting, and Participants: This randomized clinical trial was conducted in tertiary newborn intensive care units recruited from 2012 to 2016 and followed up until 2 years of age. Participants included neonates with encephalopathy at 35 weeks' gestation or more and younger than 48 hours old. Data analysis was completed in April 2021. Interventions: Randomization was to an electrographic seizure group (ESG) in which seizures detected on aEEG were treated in addition to clinical seizures or a clinical seizure group (CSG) in which only seizures detected clinically were treated. Main Outcomes and Measures: Primary outcome was death or severe disability at 2 years, defined as scores in any developmental domain more than 2 SD below the Australian mean assessed with Bayley Scales of Neonate and Toddler Development, 3rd ed (BSID-III), or the presence of cerebral palsy, blindness, or deafness. Secondary outcomes included magnetic resonance imaging brain injury score at 5 to 14 days, time to full suck feeds, and individual domain scores on BSID-III at 2 years. Results: Of 212 randomized neonates, the mean (SD) gestational age was 39.2 (1.7) weeks and 122 (58%) were male; 152 (72%) had moderate to severe hypoxic-ischemic encephalopathy (HIE) and 147 (84%) had electrographic seizures. A total of 86 neonates were included in the ESG group and 86 were included in the CSG group. Ten of 86 (9%) neonates in the ESG and 4 of 86 (4%) in the CSG died before the 2-year assessment. The odds of the primary outcome were not significantly different in the ESG group compared with the CSG group (ESG, 38 of 86 [44%] vs CSG, 27 of 86 [31%]; odds ratio [OR], 1.83; 95% CI, 0.96 to 3.49; P = .14). There was also no significant difference in those with HIE (OR, 1.77; 95% CI, 0.84 to 3.73; P = .26). There was evidence that cognitive outcomes were worse in the ESG (mean [SD] scores, ESG: 97.4 [17.7] vs CSG: 103.8 [17.3]; mean difference, -6.5 [95% CI, -1.2 to -11.8]; P = .01). There was little evidence of a difference in secondary outcomes, including time to suck feeds, seizure burden, or brain injury score. Conclusions and Relevance: Treating electrographic and clinical seizures with currently used anticonvulsants did not significantly reduce the rate of death or disability at 2 years in a heterogeneous group of neonates with seizures. Trial Registration: http://anzctr.org.au Identifier: ACTRN12611000327987.

Nasal high flow in preterm infants: A dose-finding study.

OBJECTIVE: To investigate the relationship between applied flows of nasal high flow (NHF) and physiological outcomes and work of breathing (WOB), to identify an optimal delivery flow which results in reduced WOB in preterm infants. DESIGN: A prospective observational clinical study with randomly applied NHF rates. PATIENTS AND SETTING: Preterm infants within 72 hours of commencement of NHF respiratory support. INTERVENTIONS: Infants were initially placed on 8 L/min of NHF and flows of 2, 4, and 6 L/min were then applied in random order. MEASUREMENTS AND RESULTS: WOB was measured using transcutaneous electromyography and respiratory inductance plethysmography. Physiological variables were also recorded. Measurements taken 10 minutes after each flow change were compared with 8 L/min. Sixteen infants with a median gestational age of 28 (range 24-31) weeks and postnatal age of 14 (2-55) days were included in the study. The median flow rate before the study was 6 (4-8) L/min and a fraction of inspired oxygen (FiO2 ) was 0.21 (0.21-0.26). Changes in flow resulted in changes in activity in the front diaphragm (P = .027) and intercostals (P = .034). The electrical activity of the front diaphragm at 8 L/min was significantly lower than that at 2 L/min (P = .016). Respiratory rate was lowest at 6 L/min (P = .002) and SpO2 /FiO2 was highest at 8 L/min (P < .04). CONCLUSION: In preterm infants, changes in WOB resulting from randomly applied levels of NHF can be demonstrated by measuring the electrical activity of the diaphragm and intercostal muscles with transcutaneous electromyography. In combination with physiological measurements, the similarities in electrical activity between 4, 6, and 8 L/min suggest that these three flows may be equally as effective.

Effect of randomization of nasal high flow rate in preterm infants.

OBJECTIVE: To assess the effect of nasal high flow (NHF) cannula on end-expiratory level (EEL), continuous distending pressure (CDP) and regional ventilation distribution in preterm infants. DESIGN: A prospective observational clinical study with randomly applied NHF rates. PATIENTS AND SETTING: Preterm infants requiring continuous positive airway pressure (CPAP) respiratory support in a Neonatal Intensive Care Unit. INTERVENTIONS: Infants were measured on randomly applied flow rates at 2, 4, and 6 L/min of NHF and compared with bubble CPAP. MEASUREMENTS AND RESULTS: Regional ventilation distribution and EEL were measured using electrical impedance tomography (EIT) and respiratory inductance plethysmography (RIP) in 24 preterm infants (31.19 ± 1.17 weeks corrected age). Changes in CDP were measured from the esophagus via the nasogastric tube. Physiological variables were also recorded. There were no differences in ventilation distribution, EEL or CDP between CPAP and NHF (P > .05). However, the physiological variables of FiO2 (P = .01) and SpO2 /FiO2 (P < .01) were improved on CPAP compared with NHF. CONCLUSION: NHF applied in random order with flow rates between 2 to 6 L/min was equally as good as CPAP in maintaining EEL and ventilation distribution in stable preterm infants. Overall oxygenation was better on CPAP compared to NHF.

Heating of gases during neonatal resuscitation: a bench study.

AIM: Standard practice within the neonatal unit is to use heated humidified gas as it decreases respiratory complications in neonates requiring respiratory support. Using cold unhumidified gases during resuscitation could potentially cool the baby as well as exacerbate potential lung injury. We aimed to study the temperature and humidity aspects of using heated, humidified gas for neonatal resuscitation. METHODS: A heated patient circuit was connected to a T-piece resuscitator via a humidifier. An oxygen flowmeter was set at 10 L/min. Temperature recordings at the humidifier chamber (T1), distal temperature probe (T2) and T-piece (T3) were taken over 20 min at 30s intervals. A humidity sensor was placed at T3. RESULTS: Target temperatures were not reached. Time to 36°C (mean (sd)): T1 11.1 min (1.71); T3 11.6 min (1.77). T2 took 13.6 min (1.07) to reach 39°C. T1 and T3 were within ±1°C at 5.1 min (0.6). A biphasic relationship demonstrated the time lag between the temperatures of the heated patient circuit and the humidifier chamber. T3 strongly correlated to T1 when T1 is ≥28°C (r(2)=0.85). Humidity was difficult to measure and results were inferred from temperature recordings. CONCLUSION: This in vitro test showed that heated, humidified gas is possible during neonatal resuscitation. Adequate time must be allowed for the humidifier chamber to warm to near optimal temperature. The patient circuit is initially heated faster than the humidifier chamber. The displayed T1 temperature correlates to the temperature at T3 at ≥28°C.