Obstetrics and Gynaecology - Research Publications

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    The 5-minute Apgar score and childhood school outcomes
    Selvaratnam, RJ ; Wallace, EM ; Davis, PG ; Rolnik, DL ; Fahey, M ; Davey, M-A (WILEY, 2022-10)
    AIM: To examine the association between Apgar score at 5 min and childhood developmental and educational outcome. METHODS: A population-based data linkage study of births ≥37 weeks' gestation linked to developmental outcomes at preparatory school and educational outcomes at school grades 3, 5 and 7 in Victoria, Australia. Multivariable logistic regressions and generalised estimating equations were used. RESULTS: There were 167,126 singleton infants with developmental results and 392,933 singleton infants with at least one educational result. There was an inverse relationship between Apgar score at 5 min and poor developmental and educational outcomes, with the worst outcomes among Apgar scores of 0-3. Apgar scores of 7, 8 and 9 were all associated with poorer developmental outcomes (aOR = 1.31, 95% CI: 1.12-1.54; aOR = 1.17, 95% CI: 1.05-1.29; aOR = 1.08, 95% CI: 1.02-1.13 respectively), while Apgar scores of 7 and 8 were associated with poorer educational outcomes at grades 3, 5, and 7. With progression through grades 3, 5, and 7, the extent of the difference in educational outcomes diminished (e.g. for Apgar scores of 0-3: aOR = 3.33, 95% CI: 1.85-6.00 in grade 3 and aOR = 1.49, 95% CI: 0.75-2.96 in grade 7). CONCLUSION: Apgar scores below 10 at 5 min are associated with poorer developmental and educational outcomes in school.
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    Respiratory outcomes in preterm babies: Is bronchopulmonary dysplasia important?
    Barrington, KJ ; Church, PT ; Luu, TM ; Davis, PG (WILEY, 2022-09)
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    Dynamic positive end-expiratory pressure strategies using time and pressure recruitment at birth reduce early expression of lung injury in preterm lambs
    Tingay, DG ; Pereira-Fantini, PM ; Miedema, M ; McCall, KE ; Perkins, EJ ; Dowse, G ; Schinckel, N ; Sourial, M ; Davis, PG (AMER PHYSIOLOGICAL SOC, 2022-10)
    Positive end-expiratory pressure (PEEP) is critical to the preterm lung at birth, but the optimal PEEP level remains uncertain. The objective of this study was to determine the effect of maximum PEEP levels at birth on the physiological and injury response in preterm lambs. Steroid-exposed preterm lambs (124-127 days gestation; n = 65) were randomly assigned from birth to either 1) positive pressure ventilation (PPV) at 8 cmH2O PEEP or 3-min dynamic stepwise PEEP strategy (DynPEEP), with either 2) 20 cmH2O maximum PEEP (10 PEEP second steps) or 3) 14 cmH2O maximum PEEP (20-s steps), all followed by standardized PPV for 90 min. Lung mechanics, gas exchange, regional ventilation and aeration (electrical impedance tomography), and histological and molecular measures of lung injury were compared between groups. Dynamic compliance was greatest using a maximum 20 cmH2O (DynPEEP). There were no differences in gas exchange, end-expiratory volume, and ventilator requirements. Regional ventilation became more uniform with time following all PEEP strategies. For all groups, gene expression of markers of early lung injury was greater in the gravity nondependent lung, and inversely related to the magnitude of PEEP, being lowest in the 20 cmH2O DynPEEP group overall. PEEP levels had no impact on lung injury in the dependent lung. Transient high maximum PEEP levels using dynamic PEEP strategies may confer more lung protection at birth.
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    Effects of tactile stimulation on spontaneous breathing during face mask ventilation
    Gaertner, VD ; Rueegger, CM ; Bassler, D ; O'Currain, E ; Kamlin, COF ; Hooper, SB ; Davis, PG ; Springer, L (BMJ PUBLISHING GROUP, 2022-09-01)
    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).
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    Lung volume distribution in preterm infants on non-invasive high-frequency ventilation
    Gaertner, VD ; Waldmann, AD ; Davis, PG ; Bassler, D ; Springer, L ; Thomson, J ; Tingay, DG ; Ruegger, CM (BMJ PUBLISHING GROUP, 2022-09)
    INTRODUCTION: Non-invasive high-frequency oscillatory ventilation (nHFOV) is an extension of nasal continuous positive airway pressure (nCPAP) support in neonates. We aimed to compare global and regional distribution of lung volumes during nHFOV versus nCPAP. METHODS: In 30 preterm infants enrolled in a randomised crossover trial comparing nHFOV with nCPAP, electrical impedance tomography data were recorded in prone position. For each mode of respiratory support, four episodes of artefact-free tidal ventilation, each comprising 30 consecutive breaths, were extracted. Tidal volumes (VT) in 36 horizontal slices, indicators of ventilation homogeneity and end-expiratory lung impedance (EELI) for the whole lung and for four horizontal regions of interest (non-gravity-dependent to gravity-dependent; EELINGD, EELImidNGD, EELImidGD, EELIGD) were compared between nHFOV and nCPAP. Aeration homogeneity ratio (AHR) was determined by dividing aeration in non-gravity-dependent parts of the lung through gravity-dependent regions. MAIN RESULTS: Overall, 228 recordings were analysed. Relative VT was greater in all but the six most gravity-dependent lung slices during nCPAP (all p<0.05). Indicators of ventilation homogeneity were similar between nHFOV and nCPAP (all p>0.05). Aeration was increased during nHFOV (mean difference (95% CI)=0.4 (0.2 to 0.6) arbitrary units per kilogram (AU/kg), p=0.013), mainly due to an increase in non-gravity-dependent regions of the lung (∆EELINGD=6.9 (0.0 to 13.8) AU/kg, p=0.028; ∆EELImidNGD=6.8 (1.2 to 12.4) AU/kg, p=0.009). Aeration was more homogeneous during nHFOV compared with nCPAP (mean difference (95% CI) in AHR=0.01 (0.00 to 0.02), p=0.0014). CONCLUSION: Although regional ventilation was similar between nHFOV and nCPAP, end-expiratory lung volume was higher and aeration homogeneity was slightly improved during nHFOV. The aeration difference was greatest in non-gravity dependent regions, possibly due to the oscillatory pressure waveform. The clinical importance of these findings is still unclear.
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    Addressing Moral Distress: lessons Learnt from a Non-Interventional Longitudinal Study on Moral Distress.
    Prentice, TM ; Imbulana, DI ; Gillam, L ; Davis, PG ; Janvier, A (Informa UK Limited, 2022)
    BACKGROUND: Moral distress is prevalent within the neonatal intensive care unit (NICU) and can negatively affect clinicians. Studies have evaluated the causes of moral distress and interventions to mitigate its harmful effects. However, the effects of participating in moral distress studies have not been evaluated. OBJECTIVE: To evaluate the impact of participation in a longitudinal, non-intervention research project on moral distress in the NICU. DESIGN: Clinicians who previously participated in an 18-month longitudinal research study on moral distress at two NICUs were invited to complete a questionnaire on the impact of participation. The original study required regular completion of surveys that sought predictions of death, disability and the intensity/nature of moral distress experienced by clinicians caring for extremely preterm babies. Individual and unit-wide effects were explored. Free-text responses to open-ended questions were analyzed using inductive content analysis. RESULTS: A total of 249/463 (53%) eligible clinicians participated. Participation in the original 18-month study was perceived as having a positive impact by 58% of respondents. Clinicians found articulating their views therapeutic (76%) and useful in clarifying personal opinions about the babies (85%). Free-text responses revealed the research stimulated increased reflection, validated feelings and increased dialogue amongst clinicians. Respondents generally did not find participation distressing (70%). However, a small number of physicians felt the focus of discussion shifted from the baby to the clinicians. Intensity and prevalence of moral distress did not significantly change over the 18-month period. CONCLUSIONS: Participating in moral distress research prompted regular reflection regarding attitudes toward fragile patients, improving ethical awareness. This is useful in clarifying personal views that may influence patient care. Participation also enhanced communication around difficult clinical scenarios and improved provider satisfaction. These factors are insufficient to significantly reduce moral distress in isolation.
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    Nasal High-Flow Therapy during Neonatal Endotracheal Intubation
    Hodgson, KA ; Owen, LS ; Kamlin, COF ; Roberts, CT ; Newman, SE ; Francis, KL ; Donath, SM ; Davis, PG ; Manley, BJ (MASSACHUSETTS MEDICAL SOC, 2022-04-28)
    BACKGROUND: Neonatal endotracheal intubation often involves more than one attempt, and oxygen desaturation is common. It is unclear whether nasal high-flow therapy, which extends the time to desaturation during elective intubation in children and adults receiving general anesthesia, can improve the likelihood of successful neonatal intubation on the first attempt. METHODS: We performed a randomized, controlled trial to compare nasal high-flow therapy with standard care (no nasal high-flow therapy or supplemental oxygen) in neonates undergoing oral endotracheal intubation at two Australian tertiary neonatal intensive care units. Randomization of intubations to the high-flow group or the standard-care group was stratified according to trial center, the use of premedication for intubation (yes or no), and postmenstrual age of the infant (≤28 or >28 weeks). The primary outcome was successful intubation on the first attempt without physiological instability (defined as an absolute decrease in the peripheral oxygen saturation of >20% from the preintubation baseline level or bradycardia with a heart rate of <100 beats per minute) in the infant. RESULTS: The primary intention-to-treat analysis included the outcomes of 251 intubations in 202 infants; 124 intubations were assigned to the high-flow group and 127 to the standard-care group. The infants had a median postmenstrual age of 27.9 weeks and a median weight of 920 g at the time of intubation. A successful intubation on the first attempt without physiological instability was achieved in 62 of 124 intubations (50.0%) in the high-flow group and in 40 of 127 intubations (31.5%) in the standard-care group (adjusted risk difference, 17.6 percentage points; 95% confidence interval [CI], 6.0 to 29.2), for a number needed to treat of 6 (95% CI, 4 to 17) for 1 infant to benefit. Successful intubation on the first attempt regardless of physiological stability was accomplished in 68.5% of the intubations in the high-flow group and in 54.3% of the intubations in the standard-care group (adjusted risk difference, 15.8 percentage points; 95% CI, 4.3 to 27.3). CONCLUSIONS: Among infants undergoing endotracheal intubation at two Australian tertiary neonatal intensive care units, nasal high-flow therapy during the procedure improved the likelihood of successful intubation on the first attempt without physiological instability in the infant. (Funded by the National Health and Medical Research Council; Australian New Zealand Clinical Trials Registry number, ACTRN12618001498280.).
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    Quantifying lung aeration in neonatal lambs at birth using lung ultrasound
    Pryor, EJ ; Blank, DA ; Hooper, SB ; Crossley, KJ ; Badurdeen, S ; Pollock, JA ; Stainsby, AV ; Croton, LCP ; O'Connell, DW ; Hall, CJ ; Maksimenko, A ; Hausermann, D ; Davis, PG ; Kitchen, MJ (FRONTIERS MEDIA SA, 2022-09-28)
    BACKGROUND: Lung ultrasound (LUS) is a safe and non-invasive tool that can potentially assess regional lung aeration in newborn infants and reduce the need for X-ray imaging. LUS produces images with characteristic artifacts caused by the presence of air in the lung, but it is unknown if LUS can accurately detect changes in lung air volumes after birth. This study compared LUS images with lung volume measurements from high-resolution computed tomography (CT) scans to determine if LUS can accurately provide relative measures of lung aeration. METHODS: Deceased near-term newborn lambs (139 days gestation, term ∼148 days) were intubated and the chest imaged using LUS (bilaterally) and phase contrast x-ray CT scans at increasing static airway pressures (0-50 cmH2O). CT scans were analyzed to calculate regional air volumes and correlated with measures from LUS images. These measures included (i) LUS grade; (ii) brightness (mean and coefficient of variation); and (iii) area under the Fourier power spectra within defined frequency ranges. RESULTS: All LUS image analysis techniques correlated strongly with air volumes measured by CT (p < 0.01). When imaging statistics were combined in a multivariate linear regression model, LUS predicted the proportion of air in the underlying lung with moderate accuracy (95% prediction interval ± 22.15%, r 2 = 0.71). CONCLUSION: LUS can provide relative measures of lung aeration after birth in neonatal lambs. Future studies are needed to determine if LUS can also provide a simple means to assess air volumes and individualize aeration strategies for critically ill newborns in real time.