Extubation generates lung volume inhomogeneity in preterm infants.

OBJECTIVE: To evaluate the feasibility of electrical impedance tomography (EIT) to describe the regional tidal ventilation (VT) and change in end-expiratory lung volume (EELV) patterns in preterm infants during the process of extubation from invasive to non-invasive respiratory support. DESIGN: Prospective observational study. SETTING: Single-centre tertiary neonatal intensive care unit. PATIENTS: Preterm infants born <32 weeks' gestation who were being extubated to nasal continuous positive airway pressure as per clinician discretion. INTERVENTIONS: EIT measurements were taken in supine infants during elective extubation from synchronised positive pressure ventilation (SIPPV) before extubation, during and then at 2 and 20 min after commencing nasal continuous positive applied pressure (nCPAP). Extubation and pressure settings were determined by clinicians. MAIN OUTCOME MEASURES: Global and regional ΔEELV and ΔVT, heart rate, respiratory rate and oxygen saturation were measured throughout. RESULTS: Thirty infants of median (range) 2 (1, 21) days were extubated to a median (range) CPAP 7 (6, 8) cm H2O. SpO2/FiO2 ratio was a mean (95% CI) 50 (35, 65) lower 20 min after nCPAP compared with SIPPV. EELV was lower at all points after extubation compared with SIPPV, and EELV loss was primarily in the ventral lung (p=0.04). VT was increased immediately after extubation, especially in the central and ventral regions of the lung, but the application of nCPAP returned VT to pre-extubation patterns. CONCLUSIONS: EIT was able to describe the complex lung conditions occurring during extubation to nCPAP, specifically lung volume loss and greater use of the dorsal lung. EIT may have a role in guiding peri-extubation respiratory support.

Effects of tactile stimulation on spontaneous breathing during face mask ventilation.

OBJECTIVE: We sought to determine the effect of stimulation during positive pressure ventilation (PPV) on the number of spontaneous breaths, exhaled tidal volume (VTe), mask leak and obstruction. DESIGN: Secondary analysis of a prospective, randomised trial comparing two face masks. SETTING: Single-centre delivery room study. PATIENTS: Newborn infants ≥34 weeks' gestation at birth. METHODS: Resuscitations were video recorded. Tactile stimulations during PPV were noted and the timing, duration and surface area of applied stimulus were recorded. Respiratory flow waveforms were evaluated to determine the number of spontaneous breaths, VTe, leak and obstruction. Variables were recorded throughout each tactile stimulation episode and compared with those recorded in the same time period immediately before stimulation. RESULTS: Twenty of 40 infants received tactile stimulation during PPV and we recorded 57 stimulations during PPV. During stimulation, the number of spontaneous breaths increased (median difference (IQR): 1 breath (0-3); padj<0.001) and VTe increased (0.5 mL/kg (-0.5 to 1.7), padj=0.028), whereas mask leak (0% (-20 to 1), padj=0.12) and percentage of obstructed inflations (0% (0-0), padj=0.14) did not change, compared with the period immediately prior to stimulation. Increased duration of stimulation (padj<0.001) and surface area of applied stimulus (padj=0.026) were associated with a larger increase in spontaneous breaths in response to tactile stimulation. CONCLUSIONS: Tactile stimulation during PPV was associated with an increase in the number of spontaneous breaths compared with immediately before stimulation without a change in mask leak and obstruction. These data inform the discussion on continuing stimulation during PPV in term infants. TRIAL REGISTRATION NUMBER: Australian and New Zealand Clinical Trial Registry (ACTRN12616000768493).

Neonatal videolaryngoscopy as a teaching aid: the trainees' perspective.

INTRODUCTION: Neonatal intubation is a challenging skill to acquire. A randomised controlled trial (RCT) found junior trainees had higher intubation success rates if their supervisor shared their airway view on a videolaryngoscope screen compared with intubations where the supervisor could not see the videolaryngoscope screen. The intubations in the trial were supervised by a group of experienced neonatologists who developed an intubation teaching package that aimed to be informative, consistent and supportive. We surveyed the trainees to assess their experiences of the intubation attempts. METHODS: Trainees participating in the RCT completed questionnaires anonymously after each intubation attempt. Questionnaires used 5-point Likert scales and free comment sections. Quantitative analysis was performed using descriptive statistics. In a qualitative analysis, free comments were coded to identify central recurring themes. RESULTS: Two hundred and six questionnaires were completed by 36 trainees. The majority reported that the guidance received during intubation was helpful, the postprocedure feedback was educational and their confidence levels were increased. Trainees appreciated a controlled environment and calm, consistent guidance. They found intubations in the delivery room, those involving unstable infants, large audiences and parental presence more stressful. Responses were positive whether the videolaryngoscope screen was visible or covered, emphasising the importance of consistent guidance. Overall, 16% of intubations were reported as intimidating. CONCLUSION: The shared airway view offered by videolaryngoscopy was well received. In addition, taking measures to control the setting, with standardised guidance and feedback, improved confidence and created a more positive learning experience.

Physiological responses to facemask application in newborns immediately after birth.

OBJECTIVE: Application of a face mask may induce apnoea and bradycardia, possibly via the trigeminocardiac reflex (TCR). We aimed to describe rates of apnoea and bradycardia in term and late-preterm infants following facemask application during neonatal stabilisation and compare the effects of first facemask application with subsequent applications. DESIGN: Subgroup analysis of a prospective, randomised trial comparing two face masks. SETTING: Single-centre study in the delivery room PATIENTS: Infants>34 weeks gestational age at birth METHODS: Resuscitations were video recorded. Airway flow and pressure were measured using a flow sensor. The effect of first and subsequent facemask applications on spontaneously breathing infants were noted. When available, flow waveforms as well as heart rate (HR) were assessed 20 s before and 30 s after each facemask application. RESULTS: In total, 128 facemask applications were evaluated. In eleven percent of facemask applications infants stopped breathing. The first application was associated with a higher rate of apnoea than subsequent applications (29% vs 8%, OR (95% CI)=4.76 (1.41-16.67), p=0.012). On aggregate, there was no change in median HR over time. In the interventions associated with apnoea, HR dropped by 38bpm [median (IQR) at time of facemask application: 134bpm (134-150) vs 96bpm (94-102) 20 s after application; p=0.25] and recovered within 30 s. CONCLUSIONS: Facemask applications in term and late-preterm infants during neonatal stabilisation are associated with apnoea and this effect is more pronounced after the first compared with subsequent applications. Healthcare providers should be aware of the TCR and vigilant when applying a face mask to newborn infants. TRIAL REGISTRATION NUMBER: ACTRN12616000768493.

Pulseless electrical activity: a misdiagnosed entity during asphyxia in newborn infants?

BACKGROUND: The 2015 neonatal resuscitation guidelines added ECG as a recommended method of assessment of an infant's heart rate (HR) when determining the need for resuscitation at birth. However, a recent case report raised concerns about this technique in the delivery room. OBJECTIVES: To compare accuracy of ECG with auscultation to assess asystole in asphyxiated piglets. METHODS: Neonatal piglets had the right common carotid artery exposed and enclosed with a real-time ultrasonic flow probe and HR was continuously measured and recorded using ECG. This set-up allowed simultaneous monitoring of HR via ECG and carotid blood flow (CBF). The piglets were exposed to 30 min normocapnic alveolar hypoxia followed by asphyxia until asystole, achieved by disconnecting the ventilator and clamping the endotracheal tube. Asystole was defined as zero carotid blood flow and was compared with ECG traces and auscultation for heart sounds using a neonatal/infant stethoscope. RESULTS: Overall, 54 piglets were studied with a median (IQR) duration of asphyxia of 325 (200-491) s. In 14 (26%) piglets, CBF, ECG and auscultation identified asystole. In 23 (43%) piglets, we observed no CBF and no audible heart sounds, while ECG displayed an HR ranging from 15 to 80/min. Sixteen (30%) piglets remained bradycardic (defined as HR of <100/min) after 10 min of asphyxia, identified by CBF, ECG and auscultation. CONCLUSION: Clinicians should be aware of the potential inaccuracy of ECG assessment during asphyxia in newborn infants and should rather rely on assessment using a combination of auscultation, palpation, pulse oximetry and ECG.

Outcomes following antenatal identification of hydrops fetalis: a single-centre experience from 2001 to 2012.

OBJECTIVE: To describe the aetiologies and outcomes of pregnancies complicated by hydrops fetalis (HF). STUDY DESIGN: Case series of all pregnancies complicated by HF managed at The Royal Women's Hospital (RWH), Melbourne, Australia, between 2001 and 2012. Multiple pregnancies, and cases where antenatal care was not provided at RWH were excluded. Cases were identified from neonatal and obstetric databases. Data were extracted from maternal and neonatal case files, electronic pathology and radiology reports, and obstetric and neonatal databases. RESULTS: Over 12 years, 131 fetuses with HF with a median (IQR) gestational age (GA) at diagnosis of 24 (20-30) weeks were included in the analysis. There were 65 liveborn infants with a median (IQR) GA at birth of 33 (31-37) weeks and a median (IQR) birthweight Z-score of 1.4 (0.4-2.2). Overall survival from diagnosis was 27% (36/131) increasing to 55% (36/65) if born alive. CONCLUSIONS: The perinatal mortality risk for fetuses and newborn infants with HF is high with important differences dependent on underlying diagnosis and the time at which counselling is provided. Clinicians need to be aware of the outcomes of both fetuses and neonates with this condition.

Analysis of unsuccessful intubations in neonates using videolaryngoscopy recordings.

OBJECTIVES: Neonatal intubation is a difficult skill to learn and teach. If an attempt is unsuccessful, the intubator and instructor often cannot explain why. This study aims to review videolaryngoscopy recordings of unsuccessful intubations and explain the reasons why attempts were not successful. STUDY DESIGN: This is a descriptive study examining videolaryngoscopy recordings obtained from a randomised controlled trial that evaluated if neonatal intubation success rates of inexperienced trainees were superior if they used a videolaryngoscope compared with a laryngoscope. All recorded unsuccessful intubations were included and reviewed independently by two reviewers blinded to study group. Their assessment was correlated with the intubator's perception as reported in a postintubation questionnaire. The Cormack-Lehane classification system was used for objective assessment of laryngeal view. RESULTS: Recordings and questionnaires from 45 unsuccessful intubations were included (15 intervention and 30 control). The most common reasons for an unsuccessful attempt were oesophageal intubation and failure to recognise the anatomy. In 36 (80%) of intubations, an intubatable view was achieved but was then either lost, not recognised or there was an apparent inability to correctly direct the endotracheal tube. Suctioning was commonly performed but rarely improved the view. CONCLUSIONS: Lack of intubation success was most commonly due to failure to recognise midline anatomical structures. Trainees need to be taught to recognise the uvula and epiglottis and use these landmarks to guide intubation. Excessive secretions are rarely a factor in elective and premedicated intubations, and routine suctioning should be discouraged. Better blade design may make it easier to direct the tube through the vocal cords.

Physical stimulation of newborn infants in the delivery room.

OBJECTIVE: Neonatal resuscitation guidelines recommend that newborn infants are stimulated to assist with the establishment of regular respirations. The mode, site of application and frequency of stimulations are not stipulated in these guidelines. The effectiveness of stimulation in improving neonatal transition outcomes is poorly described. METHODS: We conducted a retrospective review of video recordings of neonatal resuscitation at a tertiary perinatal centre. Four different types of stimulation (drying, chest rub, back rub and foot flick) were defined a priori and the frequency and infant response were documented. RESULTS: A total of 120 video recordings were reviewed. Seventy-five (63%) infants received at least one episode of stimulation and 70 (58%) infants were stimulated within the first minute after birth. Stimulation was less commonly provided to infants <30 weeks' gestation (median (IQR) number of stimulations: 0 (0-1)) than infants born ≥30 weeks' gestation (1 (1-3); p<0.001). The most common response to stimulation was limb movement followed by infant cry and facial grimace. Truncal stimulation (drying, chest rub, back rub) was associated with more crying and movement than foot flicks. CONCLUSION: Less mature infants are stimulated less frequently compared with more mature infants and many very preterm infants do not receive any stimulation. Most infants were stimulated within the first minute as recommended in resuscitation guidelines. Rubbing the trunk may be most effective but this needs to be confirmed in prospective studies.

Lung ultrasound immediately after birth to describe normal neonatal transition: an observational study.

OBJECTIVE: Lung ultrasound (LUS) has shown promise as a diagnostic tool for the evaluation of the newborn with respiratory distress. No study has described LUS during 'normal' transition. Our goal was to characterise the appearance of serial LUS in healthy newborns from the first minutes after birth until airway liquid clearance is achieved. STUDY DESIGN: Prospective observational study. SETTING: Single-centre tertiary perinatal centre in Australia. PATIENTS: Of 115 infants born at ≥35 weeks gestational age, mean (SD) gestational age of 386/7 weeks±11 days, mean birth weight of 3380±555 g, 51 were delivered vaginally, 14 via caesarean section (CS) after labour and 50 infants via elective CS. INTERVENTIONS: We obtained serial LUS videos via the right and left axillae at 1-10 min, 11-20 min and 1, 2, 4 and 24 hours after birth. MAIN OUTCOME MEASURES: LUS videos were graded for aeration and liquid clearance according to a previously validated system. RESULTS: We analysed 1168 LUS video recordings. As assessed by LUS, lung aeration and airway liquid clearance occurred quickly. All infants had an established pleural line at the first examination (median=2 (1-4) min). Only 14% of infants had substantial liquid retention at 10 min after birth. 49%, 78% and 100% of infants had completed airway liquid clearance at 2, 4 and 24 hours, respectively. CONCLUSIONS: In healthy transitioning newborn infants, lung aeration and partial liquid clearance are achieved on the first minutes after birth with complete liquid clearance typically achieved within the first 4 hours of birth. TRIAL REGISTRATION NUMBER: ANZCT 12615000380594.

Variability of respiratory parameters and extubation readiness in ventilated neonates.

BACKGROUND: A spontaneous breathing trial (SBT) has been used to guide suitability of extubation in VLBW infants. Respiratory variability (RV) has been used to assess extubation readiness in adults but was never investigated in preterms. The combination of a SBT and RV may further improve prediction of successful extubation. STUDY DESIGN: Using data previously collected during the SBT, the following respiratory variables were analysed: inspiratory time (T(I)), expiratory time (T(E)), T(I)/total breath time, tidal volume (V(T)) and mean inspiratory flow (V(T)/T(I)). RV was quantified using time-domain analysis for each respiratory variable and expressed as a variability index (VI). The sensitivity, specificity, positive and negative predictive values (PPV and NPV) of the SBT, each VI and combined SBT+VI were calculated. Extubation failure was defined as need of re-intubation within 72 h. RESULTS: A total of 44 infants were included. Successfully (n=36) and unsuccessfully (n=8) extubated infants had similar baseline characteristics and number of breaths analysed. VI for V(T)/T(I)was significantly decreased in the failure group. The combination of the SBT and VI of either T(I)or V(T)were the most accurate predictors of successful extubation with a sensitivity of 100% and specificity of 75% and a PPV and NPV for extubation success of 95% and 100%, respectively. CONCLUSIONS: A significant decrease in V(T)/T(I)variability occurred in infants requiring re-intubation. The combination of a SBT failure and decreased variability in T(I)or V(T)was highly predictive of failure. This combination is promising but requires prospective evaluation in a larger population.