Microbiome and its impact on fetal and neonatal brain development: current opinion in pediatrics

PURPOSE OF REVIEW

Emerging evidence suggests that the gut microbiota and its metabolites regulate neurodevelopment and cognitive functioning via a bi-directional communication system known as the microbiota-gut-brain axis (MGBA).

RECENT FINDINGS

The MGBA influences brain development and function via the hypothalamic-pituitary axis, the vagal nerve, immune signaling, bacterial production of neurotransmitters, and microbial metabolites like short-chain fatty acids, tryptophan derivatives, and bile acids. Animal studies show fetal neurodevelopment is mediated by maternal microbiota derivatives, immune activation, and diet. Furthermore, manipulation of the microbiota during critical windows of development, like antibiotic exposure and fecal microbiota transplantation, can affect cognitive functioning and behavior in mice. Evidence from human studies, particularly in preterm infants, also suggests that a disrupted gut microbiota colonization may negatively affect neurodevelopment. Early microbial signatures were linked to favorable and adverse neurodevelopmental outcomes.

SUMMARY

The link between the gut microbiota and the brain is evident. Future studies, including experimental studies, larger participant cohort studies with longitudinal analyses of microbes, their metabolites, and neurotransmitters, and randomized controlled trials are warranted to further elucidate the mechanisms of the MGBA. Identification of early, predictive microbial markers could pave the way for the development of novel early microbiota-based intervention strategies, such as targeted probiotics, and vaginal or fecal microbiota transplantation, aimed at improving infant neurodevelopment.

The Effects of a New Wireless Non-Adhesive Cardiorespiratory Monitoring Device on the Skin Conditions of Preterm Infants

AIM

The aim of our study was to investigate skin conditions when wearing and removing a novel wireless non-adhesive cardiorespiratory monitoring device for neonates (Bambi-Belt) compared to standard adhesive electrodes.

STUDY DESIGN

This was a prospective study including preterm neonates requiring cardiorespiratory monitoring. Besides standard electrodes, the infants wore a Bambi Belt for 10 consecutive days. Their skin conditions were assessed using Trans Epidermal Water Loss (TEWL) and the Neonatal Skin Condition Score (NSCS) after daily belt and standard electrode removal. The ∆TEWL was calculated as the difference between the TEWL at the device's location (Bambi-Belt/standard electrode) and the adjacent control skin location, with a higher ∆TEWL indicating skin damage.

RESULTS

A total of 15 infants (gestational age (GA): 24.1-35.6 wk) were analyzed. The ΔTEWL significantly increased directly after electrode removal (10.95 ± 9.98 g/m2/h) compared to belt removal (5.18 ± 6.71 g/m2/h; F: 8.73, p = 0.004) and after the washout period (3.72 ± 5.46 g/m2/h vs. 1.86 ± 3.35 g/m2/h; F: 2.84, p = 0.09), although the latter did not reach statistical significance. The TEWL was not influenced by prolonged belt wearing. No significant differences in the NSCS score were found between the belt and electrode (OR: 0.69, 95% CI [0.17, 2.88], p = 0.6).

CONCLUSION

A new wireless non-adhesive device for neonatal cardiorespiratory monitoring was well tolerated in preterm infants and may be less damaging during prolonged wearing.

Timing of surfactant treatment in respiratory distress syndrome

The introduction of exogenous surfactant in the 1980s has resulted in an improved survival of very preterm infants with respiratory distress syndrome (RDS). Randomized controlled trials conducted before 2000 have shown that the magnitude of this beneficial effect strongly depends on the timing of surfactant treatment, i.e. the earlier surfactant is administered after birth the better. However, the initial mode of respiratory support in infants with RDS has changed dramatically over the last decades, moving from invasive to non-invasive support. Furthermore, new, less invasive techniques to administer surfactant have been introduced to match this non-invasive approach. This review summarizes the evidence on how these practice changes impacted the effect of surfactant timing on mortality and morbidity in preterm infants with RDS.

Accidental rupture of membranes and neonatal infection after labor induction with silicone or latex balloon catheters: A retrospective cohort study

OBJECTIVE(S)

Accidental rupture of membranes (acROM), an insertion-related complication of the balloon catheter for labor induction, may prolong the duration of ruptured membranes. Prolonged rupture of membranes is associated with an increased risk of intra-uterine infection with possibly neonatal infection as result. Little is known about safety profiles of different catheters regarding the occurrence of these complications. This study compares the incidence of neonatal early-onset sepsis (EOS) and acROM in women receiving either silicone or latex balloon catheters.

STUDY DESIGN

A retrospective cohort study was performed including 2200 women (silicone balloon catheter, n = 1100 vs. latex balloon catheter, n = 1100). The primary outcomes were the incidence of acROM, and suspected and proven neonatal EOS. Secondary outcomes were: prolonged rupture of membranes, intrapartum fever, pre- or postnatal neonatal exposure to antibiotics, and perinatal outcomes. A subgroup analysis was performed between women with and without acROM.

RESULTS

No statistically significant difference with regard to suspected or proven EOS was seen between the silicone and latex groups. The acROM rate was significantly higher in the silicone group compared to the latex group (2.9 % and 0.3 %, p < 0.01). Prolonged rupture of membranes was significantly more common in the silicone group compared to the latex group (5.0 % and 2.4 %, p < 0.01), as was the use of intrapartum antibiotics (12.7 % and 9.6 %, p = 0.02). Neonates were significantly more often exposed to pre- or postnatal antibiotics in the silicone group compared to the latex group (17.6 % and 13.6 %, p = 0.01). Subgroup analysis showed significantly more suspected and proven neonatal EOS when catheter-insertion was complicated with acROM (11.4 % and 20.0 %), compared to cases without acROM (3.8 % and 2.5 %), irrespective of the type of catheter used.

CONCLUSION(S)

The use of silicone balloon catheters for labor induction results in higher rates of acROM, prolonged rupture of membranes and use of intrapartum antibiotics, compared to latex balloon catheters. No statistically significant differences were found in the occurrence of suspected or proven neonatal EOS, however neonates from the silicone group were more often exposed to pre- or postnatal antibiotics. When acROM occurs, irrespective of type of catheter used, suspected and proven neonatal EOS was seen more often.

Cardiorespiratory monitoring with a wireless and nonadhesive belt measuring diaphragm activity in preterm and term infants: A multicenter non-inferiority study

INTRODUCTION

We determined if the heart rate (HR) monitoring performance of a wireless and nonadhesive belt is non-inferior compared to standard electrocardiography (ECG). Secondary objective was to explore the belt's respiratory rate (RR) monitoring performance compared to chest impedance (CI).

METHOD

In this multicenter non-inferiority trial, preterm and term infants were simultaneously monitored with the belt and conventional ECG/CI for 24 h. HR monitoring performance was estimated with the HR difference and ability to detect cardiac events compared to the ECG, and the incidence of HR-data loss per second. These estimations were statistically compared to prespecified margins to confirm equivalence/non-inferiority. Exploratory RR analyses estimated the RR trend difference and ability to detect apnea/tachypnea compared to CI, and the incidence of RR-data loss per second.

RESULTS

Thirty-nine infants were included. HR monitoring with the belt was non-inferior to the ECG with a mean HR difference of 0.03 beats per minute (bpm) (standard error [SE] = 0.02) (95% limits of agreement [LoA]: [-5 to 5] bpm) (p < 0.001). Second, sensitivity and positive predictive value (PPV) for cardiac event detection were 94.0% (SE = 0.5%) and 92.6% (SE = 0.6%), respectively (p ≤ 0.001). Third, the incidence of HR-data loss was 2.1% (SE = 0.4%) per second (p < 0.05). The exploratory analyses of RR showed moderate trend agreement with a mean RR-difference of 3.7 breaths/min (SE = 0.8) (LoA: [-12 to 19] breaths/min), but low sensitivities and PPV's for apnea/tachypnea detection. The incidence of RR-data loss was 2.2% (SE = 0.4%) per second.

CONCLUSION

The nonadhesive, wireless belt showed non-inferior HR monitoring and a moderate agreement in RR trend compared to ECG/CI. Future research on apnea/tachypnea detection is required.

Predicting CPAP failure after less invasive surfactant administration (LISA) in preterm infants by machine learning model on vital parameter data: a pilot study

Objective. Less invasive surfactant administration (LISA) has been introduced to preterm infants with respiratory distress syndrome on continuous positive airway pressure (CPAP) support in order to avoid intubation and mechanical ventilation. However, after this LISA procedure, a significant part of infants fails CPAP treatment (CPAP-F) and requires intubation in the first 72 h of life, which is associated with worse complication free survival chances. The aim of this study was to predict CPAP-F after LISA, based on machine learning (ML) analysis of high resolution vital parameter monitoring data surrounding the LISA procedure.Approach. Patients with a gestational age (GA) <32 weeks receiving LISA were included. Vital parameter data was obtained from a data warehouse. Physiological features (HR, RR, peripheral oxygen saturation (SpO2) and body temperature) were calculated in eight 0.5 h windows throughout a period 1.5 h before to 2.5 h after LISA. First, physiological data was analyzed to investigate differences between the CPAP-F and CPAP-Success (CPAP-S) groups. Next, the performance of two types of ML models (logistic regression: LR, support vector machine: SVM) for the prediction of CPAP-F were evaluated.Main results. Of 51 included patients, 18 (35%) had CPAP-F. Univariate analysis showed lower SpO2, temperature and heart rate variability (HRV) before and after the LISA procedure. The best performing ML model showed an area under the curve of 0.90 and 0.93 for LR and SVM respectively in the 0.5 h window directly after LISA, with GA, HRV, respiration rate and SpO2as most important features. Excluding GA decreased performance in both models.Significance. In this pilot study we were able to predict CPAP-F with a ML model of patient monitor signals, with best performance in the first 0.5 h after LISA. Using ML to predict CPAP-F based on vital signals gains insight in (possibly modifiable) factors that are associated with LISA failure and can help to guide personalized clinical decisions in early respiratory management.

Time to first passage of meconium and defecation frequency preceding necrotizing enterocolitis in preterm infants: a case-control study

Necrotizing enterocolitis (NEC) is associated with significant morbidity and mortality in preterm infants. Early recognition and treatment of NEC are critical to improving outcomes. Enteric nervous system (ENS) immaturity has been proposed as a key factor in NEC pathophysiology. Gastrointestinal dysmotility is associated with ENS immaturity and may serve as a predictive factor for the development of NEC. In this case-control study, preterm infants (gestational age (GA) < 30 weeks) were included in two level-IV neonatal intensive care units. Infants with NEC in the first month of life were 1:3 matched to controls based on GA (± 3 days). Odds ratios for NEC development were analyzed by logistic regression for time to first passage of meconium (TFPM), duration of meconial stool, and mean daily defecation frequency over the 72 h preceding clinical NEC onset (DF < T0). A total of 39 NEC cases and 117 matched controls (median GA 27 + 4 weeks) were included. Median TFPM was comparable in cases and controls (36 h [IQR 13-65] vs. 30 h [IQR 9-66], p = 0.83). In 21% of both cases and controls, TFPM was ≥ 72 h (p = 0.87). Duration of meconial stool and DF < T0 were comparable in the NEC and control group (median 4 and 3, resp. in both groups). Odds of NEC were not significantly associated with TFPM, duration of meconial stools, and DF < T0 (adjusted odds ratio [95% confidence interval]: 1.00 [0.99-1.03], 1.16 [0.86-1.55] and 0.97 [0.72-1.31], resp.).

CONCLUSION

In this cohort, no association was found between TFPM, duration of meconium stool, and DF < T0 and the development of NEC.

WHAT IS KNOWN

• Necrotizing enterocolitis (NEC) is a life-threatening acute intestinal inflammatory disease of the young preterm infant. Early clinical risk factors for NEC have been investigated in order to facilitate early diagnosis and treatment. • Signs of disrupted gastrointestinal mobility, such as gastric retention and paralytic ileus, have been established to support the diagnosis of NEC. Nevertheless, defecation patterns have insufficiently been studied in relation to the disease.

WHAT IS NEW

• Defecation patterns in the three days preceding NEC did not differ from gestational age-matched controls of corresponding postnatal age. Additionally, the first passage of meconium and the duration of meconium passage were comparable between cases and controls. Currently, defecation patterns are not useful as early warning signs for NEC. It remains to be elucidated whether these parameters are different based on the location of intestinal necrosis.

Duration of Neonatal Antibiotic Exposure in Preterm Infants in Association with Health and Developmental Outcomes in Early Childhood

Over 90% of preterm neonates are, often empirically, exposed to antibiotics as a potentially life-saving measure against sepsis. Long-term outcome in association with antibiotic exposure (NABE) has insufficiently been studied after preterm birth. We investigated the association of NABE-duration with early-childhood developmental and health outcomes in preterm-born children and additionally assessed the impact of GA on outcomes. Preterm children (GA < 30 weeks) participating in a multicenter cohort study were approached for follow-up. General expert-reviewed health questionnaires on respiratory, atopic and gastrointestinal symptoms were sent to parents of children > 24 months' corrected age (CA). Growth and developmental assessments (Bayley Scales of Infant and Toddler Development (BSID) III) were part of standard care assessment at 24 months' CA. Uni- and multivariate regressions were performed with NABE (per 5 days) and GA (per week) as independent variables. Odds ratios (OR) for health outcomes were adjusted (aOR) for confounders, where appropriate. Of 1079 infants whose parents were approached, 347 (32%) responded at a mean age of 4.6 years (SD 0.9). In children with NABE (97%), NABE duration decreased by 1.6 days (p < 0.001) per week of gestation. Below-average gross-motor development (BSID-III gross-motor score < 8) was associated with duration of NABE (aOR = 1.28; p = 0.04). The aOR for constipation was 0.81 (p = 0.04) per gestational week. Growth was inversely correlated with GA. Respiratory and atopic symptoms were not associated with NABE, nor GA. We observed that prolonged NABE after preterm birth was associated with below-average gross-motor development at 24 months' CA, while a low GA was associated with lower weight and stature Z-scores and higher odds for constipation.

Fecal Volatile Metabolomics Predict Gram-Negative Late-Onset Sepsis in Preterm Infants: A Nationwide Case-Control Study

Early detection of late-onset sepsis (LOS) in preterm infants is crucial since timely treatment initiation is a key prognostic factor. We hypothesized that fecal volatile organic compounds (VOCs), reflecting microbiota composition and function, could serve as a non-invasive biomarker for preclinical pathogen-specific LOS detection. Fecal samples and clinical data of all preterm infants (≤30 weeks’ gestation) admitted at nine neonatal intensive care units in the Netherlands and Belgium were collected daily. Samples from one to three days before LOS onset were analyzed by gas chromatography—ion mobility spectrometry (GC-IMS), a technique based on pattern recognition, and gas chromatography—time of flight—mass spectrometry (GC-TOF-MS), to identify unique metabolites. Fecal VOC profiles and metabolites from infants with LOS were compared with matched controls. Samples from 121 LOS infants and 121 matched controls were analyzed using GC-IMS, and from 34 LOS infants and 34 matched controls using GC-TOF-MS. Differences in fecal VOCs were most profound one and two days preceding Escherichia coli LOS (Area Under Curve; p-value: 0.73; p = 0.02, 0.83; p < 0.002, respectively) and two and three days before gram-negative LOS (0.81; p < 0.001, 0.85; p < 0.001, respectively). GC-TOF-MS identified pathogen-specific discriminative metabolites for LOS. This study underlines the potential for VOCs as a non-invasive preclinical diagnostic LOS biomarker.

Predictive Intelligent Control of Oxygenation in Preterm Infants: A Two-Center Feasibility Study

INTRODUCTION

Supplemental oxygen therapy is a mainstay of modern neonatal intensive care for preterm infants. However, both insufficient and excess oxygen delivery are associated with adverse outcomes. Automated or closed loop FiO2 control has been developed to keep SpO2 within a predefined target range more effectively.

METHODS

The aim of this study was to investigate the feasibility of closed loop FiO2 control by Predictive Intelligent Control of Oxygenation (PRICO) on the Fabian ventilator in maintaining SpO2 within a target range (88/89-95%) in preterm infants on different modes of invasive and noninvasive respiratory support. In two tertiary neonatal intensive care units, preterm infants with an FiO2 >0.21 were included and received an 8 h nonblinded treatment period of closed loop FiO2 control by PRICO, flanked by two 8 h control periods of routine manual control (RMC1 and RMC2).

RESULTS

32 preterm infants were included (median gestational age 26 + 5 weeks [IQR 25 + 5-27 + 6], median birthweight 828 grams [IQR 704-930]). Six patients received invasive respiratory support, while 26 received noninvasive respiratory support (18 CPAP, 4 DuoPAP, and 4 nasal IMV). The time percentage within the SpO2 target range was increased with PRICO (74.4% [IQR 67.8-78.5]) compared to RMC1 (65.8% [IQR 51.1-77.8]; p = 0.011) and RMC2 (60.6% [IQR 56.2-66.6]; p < 0.001) with an estimated median difference of 6.0% (95% CI 1.2-11.5) and 9.8% (95% CI 6.0-13.0), respectively.

CONCLUSION

In preterm infants on invasive and noninvasive respiratory supports, closed loop FiO2 control by PRICO compared to RMC is feasible and superior in maintaining SpO2 within target ranges.

Multicentre paired non-inferiority study of the cardiorespiratory monitoring performance of the wireless and non-adhesive Bambi® belt measuring diaphragm activity in neonates: study protocol

INTRODUCTION

Cardiorespiratory monitoring is used in the neonatal intensive care unit (NICU) to assess the clinical status of newborn infants and detect critical deteriorations in cardiorespiratory function. Currently, heart rate (HR) is monitored by electrocardiography (ECG) and respiration by chest impedance (CI). Disadvantages of current monitoring techniques are usage of wired adhesive electrodes which may damage the skin and hinder care. The Bambi® belt is a wireless and non-adhesive alternative that enables cardiorespiratory monitoring by measuring electrical activity of the diaphragm via transcutaneous electromyography. A previous study showed feasibility of the Bambi® belt and this study compares the belt performance to ECG and CI.

METHODS AND ANALYSIS

This multicentre non-inferiority paired study will be performed in the NICU of the Máxima Medical Center (MMC) in Veldhoven and the Emma Children's Hospital, Amsterdam University Medical Centre (AmsterdamUMC) in Amsterdam, The Netherlands. 39 infants in different postmenstrual age groups (minimally 10 infants<30 weeks, between 30-32 weeks and >32 weeks) will be recruited. These infants will be monitored with the Bambi® belt in addition to standard ECG and CI for 24 hours. The primary outcome is the HR, studied with three criteria: (1) the limits of agreement of the HR measurements in terms of the second-to-second difference in the HR between the belt and standard ECG, (2) the detection of cardiac events consisting of bradycardia and tachycardia and (3) the quality of HR-monitoring. The secondary outcome is the respiratory rate (RR), studied with the criteria (1) agreement in RR-trend monitoring, (2) apnoea and tachypnoea detection and (3) reliable registrations.

ETHICS AND DISSEMINATION

This protocol was approved by the Medical Ethical Committee of the MMC and the Central Committee for Human Research. The MMC started patient recruitment in July and the AmsterdamUMC in August 2021. The results will be presented at conferences and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NL9480.

Short-Term Outcome after Repeated Less Invasive Surfactant Administration: A Retrospective Cohort Study

INTRODUCTION

Less invasive surfactant administration (LISA) to preterm infants is associated with decreased risk for death or BPD. After LISA, a considerable proportion requires a second dose of surfactant because of ongoing respiratory distress syndrome, raising a clinical dilemma between intubation or performing a repeated LISA (re-LISA) procedure. We aim to assess efficacy of re-LISA in avoiding subsequent nasal continuous positive airway pressure failure (need for intubation in the first 72 h of life; CPAP-F), to identify factors associated with subsequent CPAP-F, and to compare short-term outcomes following re-LISA to surfactant retreatment by endotracheal intubation and mechanical ventilation.

METHODS

This was an observational retrospective study in two Dutch NICUs. Inclusion criterion was infants with gestational age <32 0/7 weeks requiring a second surfactant dose. Multivariate logistic regression analysis was performed.

RESULTS

Of 209 infants requiring second surfactant dose, 132 received re-LISA. Subsequent CPAP-F was observed in 56 (42%) infants and was associated with extreme prematurity (OR 2.6, 95% CI: 1.2-5.8) and FiO2>0.5 (OR 5.4, 95% CI: 2.0-14.7). Infants receiving re-LISA had a lower risk of death or BPD compared to infants intubated for the second surfactant dose (OR 0.4, 95% CI: 0.2-0.9). Infants with CPAP-F after re-LISA had similar outcomes compared to those intubated for second surfactant dose.

CONCLUSION

Re-LISA is effective in reducing CPAP-F and is associated with lower risk of death or BPD compared to retreatment via an endotracheal tube. Infants failing CPAP after re-LISA have similar outcomes compared to intubated infants. These findings support the use of re-LISA in preterm infants with ongoing RDS.

Predictive Intelligent Control of Oxygenation (PRICO) in preterm infants on high flow nasal cannula support: a randomised cross-over study

OBJECTIVE

To investigate the efficacy of automated control of inspired oxygen (FiO2) by Predictive Intelligent Control of Oxygenation (PRICO) on the Fabian ventilator in maintaining oxygen saturation (SpO2) in preterm infants on high flow nasal cannula (HFNC) support.

DESIGN

Single-centre randomised two-period crossover study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

27 preterm infants (gestational age (GA) <30 weeks) on HFNC support with FiO2 >0.25.

INTERVENTION

A 24-hour period on automated FiO2-control with PRICO compared with a 24-hour period on routine manual control (RMC) to maintain a SpO2 level within target range of 88%-95% measured at 30 s intervals.

MAIN OUTCOME MEASURES

Primary outcome: time spent within target range (88%-95%).

SECONDARY OUTCOMES

time spent above and below target range, in severe hypoxia (SpO2 <80%) and hyperoxia (SpO2 >98%), mean SpO2 and FiO2 and manual FiO2 adjustments.

RESULTS

15 patients received PRICO-RMC and 12 RMC-PRICO. The mean time within the target range increased with PRICO: 10.8% (95% CI 7.6 to 13.9). There was a decrease in time below target range: 7.6% (95% CI 4.2 to 11.0), above target range: 3.1% (95% CI 2.9 to 6.2) and in severe hypoxia: 0.9% (95% CI 1.5 to 0.2). We found no difference in time spent in severe hyperoxia. Mean FiO2 was higher during PRICO: 0.019 (95% CI 0.006 to 0.030). With PRICO there was a reduction of manual adjustments: 9/24 hours (95% CI 6 to 12).

CONCLUSION

In preterm infants on HFNC support, automated FiO2-control by PRICO is superior to RMC in maintaining SpO2 within target range. Further validation studies with a higher sample frequency and different ventilation modes are needed.

Profound Pathogen-Specific Alterations in Intestinal Microbiota Composition Precede Late-Onset Sepsis in Preterm Infants: A Longitudinal, Multicenter, Case-Control Study

BACKGROUND

The role of intestinal microbiota in the pathogenesis of late-onset sepsis (LOS) in preterm infants is largely unexplored but could provide opportunities for microbiota-targeted preventive and therapeutic strategies. We hypothesized that microbiota composition changes before the onset of sepsis, with causative bacteria that are isolated later in blood culture.

METHODS

This multicenter case-control study included preterm infants born under 30 weeks of gestation. Fecal samples collected from the 5 days preceding LOS diagnosis were analyzed using a molecular microbiota detection technique. LOS cases were subdivided into 3 groups: gram-negative, gram-positive, and coagulase-negative Staphylococci (CoNS).

RESULTS

Forty LOS cases and 40 matched controls were included. In gram-negative LOS, the causative pathogen could be identified in at least 1 of the fecal samples collected 3 days prior to LOS onset in all cases, whereas in all matched controls, this pathogen was absent (P = .015). The abundance of these pathogens increased from 3 days before clinical onset. In gram-negative and gram-positive LOS (except CoNS) combined, the causative pathogen could be identified in at least 1 fecal sample collected 3 days prior to LOS onset in 92% of the fecal samples, whereas these pathogens were present in 33% of the control samples (P = .004). Overall, LOS (expect CoNS) could be predicted 1 day prior to clinical onset with an area under the curve of 0.78.

CONCLUSIONS

Profound preclinical microbial alterations underline that gut microbiota is involved in the pathogenesis of LOS and has the potential as an early noninvasive biomarker.

Detection of Volatile Organic Compounds as Potential Novel Biomarkers for Chorioamnionitis - Proof of Experimental Models

Background: Histologic chorioamnionitis is only diagnosed postnatally which prevents interventions. We hypothesized that volatile organic compounds (VOCs) in the amniotic fluid might be useful biomarkers for chorioamnionitis and that VOC profiles differ between amnionitis of different origins. Methods: Time-mated ewes received intra-amniotic injections of media or saline (controls), or live Ureaplasma parvum serovar 3 (Up) 14, 7 or 3d prior to c-section at day 124 gestational age (GA). 100 μg recombinant ovine IL-1α was instilled at 7, 3 or 1d prior to delivery. Headspace VOC profiles were measured from amniotic fluids at birth using ion mobility spectrometer coupled with multi-capillary columns. Results: 127 VOC peaks were identified. 27 VOCs differed between samples from controls and Up- or IL-1α induced amnionitis. The best discrimination between amnionitis by Up vs. IL-1α was reached by 2-methylpentane, with a sensitivity/specificity of 96/95% and a positive predictive value/negative predictive values of 96 and 95%. The concentration of 2-methylpentane in VOCs peaked 7d after intra-amniotic instillation of Up. Discussion: We established a novel method to study headspace VOC profiles of amniotic fluids. VOC profiles may be a useful tool to detect and to assess the duration of amnionitis induced by Up. 2-methylpentane was previously described in the exhalate of women with pre-eclampsia and might be a volatile biomarker for amnionitis. Amniotic fluids analyzed by ion mobility spectrometry coupled with multi-capillary columns may provide bedside diagnosis of amnionitis and understanding inflammatory mechanisms during pregnancy.

Predictive factors for surgical treatment in preterm neonates with necrotizing enterocolitis: a multicenter case-control study

Necrotizing enterocolitis (NEC) is one of the most common and lethal gastrointestinal diseases in preterm infants. Early recognition of infants in need for surgical intervention might enable early intervention. In this multicenter case-control study, performed in nine neonatal intensive care units, preterm born infants (< 30 weeks of gestation) diagnosed with NEC (stage ≥ IIA) between October 2014 and August 2017 were divided into two groups: (1) medical (conservative treatment) and (2) surgical NEC (sNEC). Perinatal, clinical, and laboratory parameters were collected daily up to clinical onset of NEC. Univariate and multivariate logistic regression analyses were applied to identify potential predictors for sNEC. In total, 73 preterm infants with NEC (41 surgical and 32 medical NEC) were included. A low gestational age (p value, adjusted odds ratio [95%CI]; 0.001, 0.91 [0.86-0.96]), no maternal corticosteroid administration (0.025, 0.19 [0.04-0.82]), early onset of NEC (0.003, 0.85 [0.77-0.95]), low serum bicarbonate (0.009, 0.85 [0.76-0.96]), and a hemodynamically significant patent ductus arteriosus for which ibuprofen was administered (0.003, 7.60 [2.03-28.47]) were identified as independent risk factors for sNEC.Conclusions: Our findings may support the clinician to identify infants with increased risk for sNEC, which may facilitate early decisive management and consequently could result in improved prognosis. What is Known: • In 27-52% of the infants with NEC, a surgical intervention is indicated during its disease course. • Absolute indication for surgical intervention is bowel perforation, whereas fixed bowel loop or clinical deterioration highly suggestive of bowel perforation or necrosi, is a relative indication. What is New: • Lower gestational age, early clinical onset, and no maternal corticosteroids administration are predictors for surgical NEC. • Low serum bicarbonate in the 3 days prior clinical onset and patent ductus arteriosus for which ibuprofen was administered predict surgical NEC.

Optimized sample preparation for fecal volatile organic compound analysis by gas chromatography-mass spectrometry

INTRODUCTION

Headspace gas chromatography-mass spectrometry (HS-GC-MS) is widely considered the gold standard of quantitative fecal VOC analysis. However, guidelines providing general recommendations for bioanalytical method application in research and clinical setting are lacking.

OBJECTIVES

To propose an evidence-based research protocol for fecal VOC analysis by HS-GC-MS, based on extensive testing of instrumental and sampling conditions on detection and quantification limits, linearity, accuracy and repeatability of VOC outcome.

METHODS

The influence of the following variables were assessed: addition of different salt solutions, injection temperature, injection speed, injection volume, septum use, use of calibration curves and fecal sample mass. Ultimately, the optimal sample preparation was assessed using fecal samples from healthy preterm infants. Fecal VOC analysis in this specific population has potential as diagnostic biomarkers, but available amount of feces is limited here, so optimization of VOC extraction is of importance.

RESULTS

We demonstrated that addition of lithium chloride enhanced the release of polar compounds (e.g. small alcohols) into the headspace. Second, a linear relationship between injection volume, speed and temperature, and fecal sample mass on the abundance of VOC was demonstrated. Furthermore, the use of a septum preserved 90% of the non-polar compounds. By application of optimal instrumental and sampling conditions, a maximum of 320 unique compounds consisting of 14 different chemical classes could be detected.

CONCLUSIONS

These findings may contribute to standardized analysis of fecal VOC by HS-GC-MS, facilitating future application of fecal VOC in clinical practice.

Small bowel intussusception in pregnant women with a history of a Roux-en-Y gastric bypass: a case series and a systematic review of the literature

Intussusception of the small intestine has been described in pregnant women with a history of a laparoscopic Roux-en-Y gastric bypass. This study provides a systematic review on the characteristics of intussusception in this population. MEDLINE, Embase, Cochrane Library, and our own hospital's electronics health records were searched for eligible studies/cases. Fifteen papers were eligible, containing 17 cases. Our hospital search included 6 cases. Seventeen of 23 intussusceptions were retrograde and were mostly (18/23) located at the jejunojejunostomy. Six patients were treated successfully with manual reduction only and 17 patients required surgical resection. Fifteen (65%) patients had an ischemic segment. Six (26%) patients delivered during the same hospital admission. One fetal death (1 of twins) was reported. Awareness of this rare but serious complication by obstetricians and bariatric surgeons is necessary to limit maternal and fetal complications.

Minimally invasive surfactant therapy failure: risk factors and outcome

OBJECTIVE

To evaluate incidence of minimally invasive surfactant therapy (MIST) failure, identify risk factors and assess the impact of MIST failure on neonatal outcome.

DESIGN

Retrospective cohort study. MIST failure was defined as need for early mechanical ventilation (<72 hours of life). Multivariate logistic regression analysis was performed to identify risk factors for MIST failure and compare outcomes between groups.

SETTING

Two tertiary neonatal intensive care centres in the Netherlands.

PATIENTS

Infants born between 24 weeks' and 31 weeks' gestational age (GA) (n=185) with MIST for respiratory distress syndrome.

INTERVENTIONS

MIST procedure with poractant alfa (100-200 mg/kg).

MAIN OUTCOME MEASURES

Continuous positive airway pressure (CPAP) failure after MIST in the first 72 hours of life.

RESULTS

30% of the infants failed CPAP after MIST. In a multivariate logistic regression analysis, four risk factors were independently associated with failure: GA <28 weeks, C reactive protein ≥10 mg/L, absence of antenatal corticosteroids and lower surfactant dose. Infants receiving 200 mg/kg surfactant had a failure rate of 14% versus 35% with surfactant dose <200 mg/kg. Mean body temperature was 0.4°C lower at neonatal intensive care unit admission and before the procedure in infants with MIST failure.Furthermore, MIST failure was independently associated with an increased risk of severe intraventricular haemorrhage.

CONCLUSION

We observed moderate MIST failure rates in concordance with the results of earlier studies. Absence of corticosteroids and lower surfactant dose are risk factors for MIST failure that may be modifiable in order to improve MIST success and patient outcome.

Effects of closed-loop automatic control of the inspiratory fraction of oxygen (FiO2-C) on outcome of extremely preterm infants - study protocol of a randomized controlled parallel group multicenter trial for safety and efficacy

Background

Most extremely low gestational age neonates (ELGANS, postmenstrual age at birth (PMA) < 28 completed weeks) require supplemental oxygen and experience frequent intermittent hypoxemic and hyperoxemic episodes. Hypoxemic episodes and exposure to inadequately high concentrations of oxygen are associated with an increased risk of retinopathy of prematurity (ROP), chronic lung disease of prematurity (BPD), necrotizing enterocolitis (NEC), neurodevelopmental impairment (NDI), and death beyond 36 weeks PMA.

Closed-loop automated control of the inspiratory fraction of oxygen (FiO₂-C) reduces time outside the hemoglobin oxygen saturation (SpO₂) target range, number and duration of hypo- and hyperoxemic episodes and caregivers’ workload. Effects on clinically important outcomes in ELGANs such as ROP, BPD, NEC, NDI and mortality have not yet been studied.

Methods

An outcome-assessor-blinded, randomized controlled, parallel-group trial was designed and powered to study the effect of FiO₂-C (in addition to routine manual control (RMC) of FiO₂), compared to RMC only, on death and severe complications related to hypoxemia and/or hyperoxemia. 2340 ELGANS with a GA of 23 + 0/7 to 27 + 6/7 weeks will be recruited in approximately 75 European tertiary care neonatal centers. Study participants are randomly assigned to RMC (control-group) or FiO₂-C in addition to RMC (intervention-group). Central randomization is stratified for center, gender and PMA at birth (< 26 weeks and ≥ 26 weeks).

FiO₂-C is provided by commercially available and CE-marked ventilators with an FiO₂-C algorithm intended for use in newborn infants. The primary outcome variable (composite of death, severe ROP, BPD or NEC) is assessed at 36 weeks PMA (or, in case of ROP, until complete vascularization of the retina, respectively). The co-primary outcome variable (composite outcome of death, language/cognitive delay, motor impairment, severe visual impairment or hearing impairment) is assessed at 24 months corrected age.

Discussion

Short-term studies on FiO₂-C showed improved time ELGANs spent within their assigned SpO₂ target range, but effects of FiO₂-C on clinical outcomes are yet unknown and will be addressed in the FiO₂-C trial. This will ensure an appropriate assessment of safety and efficacy before FiO₂-C may be implemented as standard therapy.

Trial registration

The study is registered at www.ClinicalTrials.gov: NCT03168516, May 30, 2017.

The relationship between antenatal indomethacin as a tocolytic drug and neonatal outcomes: a retrospective cohort study

INTRODUCTION

Preterm birth is associated with increased mortality and morbidity. Tocolytic drugs, such as indomethacin, are often used to postpone preterm delivery. Indomethacin has been proven to be more effective than other tocolytic agents in terms of delaying birth but is often prescribed with caution because of its potential association with adverse neonatal outcomes. We aim to study the effects of antenatal indomethacin on neonatal outcomes after controlling for potential confounders, as compared to nifedipine and/or atosiban.

METHODS

In this cohort study, we performed a retrospective analysis of maternal and neonatal data. Women were included if they received indomethacin, nifedipine or atosiban as a tocolytic drug for imminent preterm labor and gave birth at a gestational age (GA) between 23^5/7 and 32^0/7weeks, between 2010 and 2015. Main outcome measures were: neonatal death, necrotizing enterocolitis (NEC), spontaneous intestinal perforation (SIP), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), patent ductus arteriosus (PDA) and its treatment.

RESULTS

Four hundred seventy-four women, delivering 610 infants were investigated. The incidence of the following adverse neonatal outcomes were significantly higher after indomethacin use: neonatal death (p = .017), NEC (p = .026), SIP (p = .008), PDA (p = .000) and PDA ligation (p = .000). However, these associations showed to be nonsignificant after adjusting for confounders (adjusted odds ratio neonatal mortality 1.6 (0.7-3.8)), NEC 1.6 (0.6-4.4), SIP 2.8 (0.3-30.0), PDA 1.1 (0.6-2.2) and PDA ligation 2.2 (0.7-6.5).

CONCLUSIONS

The presumed association between antenatal indomethacin exposure and several adverse neonatal outcomes may be based upon indication bias. Taking important confounding factors, such as GA at birth and neonatal birth weight into account, antenatal indomethacin exposure does not result in a higher incidence of adverse neonatal outcomes. However, there may be a higher risk for spontaneous intestinal perforation.

[Breech delivery 'on all fours']

Since the publication of the results of the Term Breech Trial (TBT) in 2000 the number of planned Caesarean sections for breech presentation has increased dramatically, at the expense of vaginal breech deliveries. The favourable effect of a planned Caesarean section for breech presentation on perinatal outcomes described in the TBT could not, however, be reproduced in later trials. A planned Caesarean section does carry an increased risk of maternal complications; furthermore, a previous Caesarean section leads to higher risks for both mother and child in any subsequent pregnancy. A recent prospective study advocates vaginal breech delivery 'on all fours', a position in which the mother leans on her hands and knees during delivery. A vaginal breech delivery in this position seems to be just as safe for the child as a planned Caesarean section, while a vaginal delivery is safer for the mother than a Caesarean section. This article describes two uncomplicated vaginal breech deliveries in the all fours position.

Why -aVF can be used in STAN as a proxy for scalp electrode-derived signal; reply to comments by Kjellmer et al

The conclusion of our recent paper that performance of the STAN device in clinical practice is potentially limited by high false-negative and high false-positive STAN-event rates and loss of ST waveform assessment capacity during severe hypoxemia, evoked comments by Kjellmer, Lindecrantz and Rosén. These comments can be summarized as follows: 1) STAN analysis is based on a unipolar lead but the authors used a negative aVF lead, and they did not validate this methodology; 2) The fetuses used in the study were too young to display the signals that the authors were trying to detect. In response to these comments we now provide both a theoretical and an experimental underpinning of our approach. In an in vivo experiment in human we placed several electrodes over the head (simulating different places of a scalp electrode), simultaneously recorded Einthoven lead I and II, and constructed -aVF from these two frontal leads. Irrespective of scalp electrode placement, the correlation between any of unipolar scalp electrode-derived signals and constructed-aVF was excellent (≥ 0.92). In response to the second comment we refer to a study which demonstrated that umbilical cord occlusion resulted in rapid increase in T/QRS ratio that coincided with initial hypertension and bradycardia at all gestational ages which were tested from 0.6-0.8 gestation. The animals of our study were in this gestational range and, hence, our experimental setup can be used to assess STAN's quality to detect fetal hypoxia. In conclusion, we have clearly demonstrated the appropriateness of using-aVF as a proxy for a scalp electrode-derived signal in STAN in these preterm lambs. Investigation why STAN could not detect relevant ST-changes and instead produced erroneous alarms in our experimental setup is hampered by the fact that the exact STAN algorithm (signal processing and analysis) is not in the public domain.

Pregnant patient with acute abdominal pain and previous bariatric surgery

Pregnant women who previously had bariatric surgery may develop acute abdominal pain during pregnancy. Two patients, 38-year-old twin primigravida (gestational age of 24+6 weeks) and a 26-year-old woman (gestational age of 24+0 weeks), both of whom had laparoscopic gastric bypass surgery previously, developed abdominal pain. The patients both had diffuse abdominal pain in combination with normal blood tests and imaging. Patient B had undergone laparoscopy at another centre after 5 weeks of gestation for internal herniation. After referral to our multidisciplinary bariatric-obstetric-neonatal (MD-BON) team, diagnostic laparoscopy was advised as internal herniation was deemed possible. In both patients, internal herniation was indeed found in Petersen's space and jejunal mesenteric defect, which was closed using laparoscopic surgery. Both women delivered healthy offspring afterwards. The presence of an MD-BON team allows for an increased awareness of potential long-term complications associated with earlier bariatric surgery in pregnancy.

Necrotizing Enterocolitis, Gut Microbiota, and Brain Development: Role of the Brain-Gut Axis

Necrotizing enterocolitis (NEC) is a relatively common disease in very-low-birth-weight infants and is associated with high mortality and morbidity. In survivors, neurodevelopmental impairment is frequently seen. The exact etiology remains largely to be elucidated, but microbiota are considered to play a major role in the development of NEC. Furthermore, emerging evidence exists that the microbiota is also of importance in brain function and development. Therefore, microbiota characterization has not only potential as a diagnostic or even preventive tool to predict NEC, but may also serve as a biomarker to monitor and possibly even as a target to manipulate brain development. Analysis of fecal volatile organic compounds, which shape the volatile metabolome and reflect microbiota function and host interaction, has been shown to be of interest in the diagnosis of NEC and late-onset sepsis. In this review, we discuss evidence of the role of the complex interplay between microbiota, NEC, and brain development, including the brain-gut axis in preterm infants.

Risk Factors for Late-Onset Sepsis in Preterm Infants: A Multicenter Case-Control Study

BACKGROUND

Late-onset sepsis (LOS) in preterm infants is a leading cause of mortality and morbidity. Timely recognition and initiation of antibiotics are important factors for improved outcomes. Identification of risk factors could allow selection of infants at an increased risk for LOS.

OBJECTIVES

The aim was to identify risk factors for LOS.

METHODS

In this multicenter case-control study, preterm infants born at ≤30 weeks of gestation were included at 9 neonatal intensive care units. Detailed demographical and clinical data were collected daily up to day 28 postnatally. Clinical and demographic risk factors were identified using univariate and multivariate regression analyses in a 1: 1 matched case-control cohort.

RESULTS

In total, 755 infants were included, including 194 LOS cases (41 gram-negative cases, 152 gram-positive cases, and 1 fungus). In the case-control cohort, every additional day of parenteral feeding increased the risk for LOS (adjusted OR = 1.29; 95% CI 1.07-1.55; p = 0.006), whereas antibiotics administration decreased this risk (OR = 0.08; 95% CI 0.01-0.88; p = 0.039). These findings could largely be attributed to specific LOS-causative pathogens, since these predictive factors could be identified for gram-positive, but not for gram-negative, LOS cases. Specifically cephalosporins administration prior to clinical onset was inversely related to coagulase-negative staphylococcus LOS (CoNS-LOS) development. Formula feeding was an independent risk factor for development of CoNS-LOS (OR = 3.779; 95% CI 1.257-11.363; p = 0.018).

CONCLUSION

The length of parenteral feeding was associated with LOS, whereas breastmilk administration was protective against CoNS-LOS. A rapid advancement of enteral feeding, preferably with breastmilk, may proportionally reduce the number of parenteral feeding days and consequently the risk for LOS.

Fecal Volatile Organic Compounds in Preterm Infants Are Influenced by Enteral Feeding Composition

Fecal volatile organic compound (VOC) analysis has shown great potential as a noninvasive diagnostic biomarker for a variety of diseases. Before clinical implementation, the factors influencing the outcome of VOC analysis need to be assessed. Recent studies found that the sampling conditions can influence the outcome of VOC analysis. However, the dietary influences remains unknown, especially in (preterm) infants. Therefore, we assessed the effects of feeding composition on fecal VOC patterns of preterm infants (born at <30 weeks gestation). Two subgroups were defined: (1) daily intake >75% breastmilk (BM) feeding and (2) daily intake >75% formula milk (FM) feeding. Fecal samples, which were collected at 7, 14 and 21 days postnatally, were analyzed by an electronic nose device (Cyranose 320^®). In total, 30 preterm infants were included (15 FM, 15 BM). No differences in the fecal VOC patterns were observed at the three predefined time-points. Combining the fecal VOC profiles of these time-points resulted in a statistically significant difference between the two subgroups although this discriminative accuracy was only modest (AUC [95% CI]; p-value; sensitivity; and specificity of 0.64 [0.51–0.77]; 0.04; 68%; and 51%, respectively). Our results suggest that the influence of enteral feeding on the outcome of fecal VOC analysis cannot be ignored in this population. Furthermore, in both subgroups, the fecal VOC patterns showed a stable longitudinal course within the first month of life.

[Abdominal pain in a pregnant patient who had gastric reduction surgery: risks associated with a history of bariatric surgery]

Pregnant women who previously had bariatric surgery may develop acute abdominal pain during pregnancy that may be related to previous operations. Two patients, a 38-year-old twin-primigravida who had a gestation period of 24+6 weeks and a 26-year-old woman who had a gestation period of 24 weeks, both of whom had laparoscopic gastric bypass (RYGB) surgery 2 and 3 years previously, developed abdominal pain. The patients were not ill, but had diffuse abdominal pain in combination with normal blood tests and imaging. Patient B had undergone laparoscopy at another centre after 5 weeks of gestation for internal herniation. After referral to our multidisciplinary Bariatric-Obstetric-Neonatal (MD-BON) team, diagnostic laparoscopy was advised as internal herniation was deemed possible. In both patients, internal herniation was indeed found in Petersen's space and jejunal mesenteric defect, which was closed using laparoscopic surgery. Both women delivered healthy offspring afterwards. The presence of a MD-BON team allows for an increased awareness of potential long-term complications associated with earlier bariatric surgery in pregnancy.

ST waveform analysis for monitoring hypoxic distress in fetal sheep after prolonged umbilical cord occlusion

INTRODUCTION

The inconclusive clinical results for ST-waveform analysis (STAN) in detecting fetal hypoxemia may be caused by the signal processing of the STAN-device itself. We assessed the performance of a clinical STAN device in signal processing and in detecting hypoxemia in a fetal sheep model exposed to prolonged umbilical cord occlusion (UCO).

METHODS

Eight fetal lambs were exposed to 25 minutes of UCO. ECG recordings were analyzed during a baseline period and during UCO. STAN-event rates and timing of episodic T/QRS rise, baseline T/QRS rise and the occurrence of biphasic ST-waveforms, as well as signal loss, were assessed.

RESULTS

During baseline conditions of normoxemia, a median of 40 (IQR, 25-70) STAN-events per minute were detected, compared to 10 (IQR, 2-22) during UCO. During UCO STAN-events were detected in five subjects within 10 minutes and in six subjects after 18 minutes, respectively. Two subjects did not generate any STAN-event during UCO. Biphasic ST event rate was reduced during UCO (median 0, IQR 0-5), compared to baseline (median 32, IQR, 6-55). ST-waveforms could not be assessed in 62% of the recording time during UCO, despite a good quality of the ECG signal.

CONCLUSIONS

The STAN device showed limitations in detecting hypoxemia in fetal sheep after prolonged UCO. The STAN device produced high false positive event rates during baseline and did not detect T/QRS changes adequately after prolonged fetal hypoxemia. During 14% of baseline and 62% of the UCO period, the STAN-device could not process the ECG signal, despite its good quality. Resolving these issues may improve the clinical performance of the STAN device.

Development of severe bronchopulmonary dysplasia is associated with alterations in fecal volatile organic compounds

BackgroundThe aim of this study was to evaluate the potential of fecal volatile organic compounds (VOCs), obtained by means of an electronic nose device (Cyranose 320), as early non-invasive biomarker for BPD.MethodsIn this nested case-control study performed at three Neonatal Intensive Care Units, fecal samples obtained at postnatal age of 7, 14, 21, and 28 days from preterm infants with severe bronchopulmonary dysplasia (BPD) were compared with fecal VOC profiles from matched controls. Microbiota analysis was performed by means of IS-pro technique on fecal samples collected at 28 days postnatally.ResultsVOC profiles of infants developing severe BPD (n=15) could be discriminated from matched controls (n=15) at postnatal age of 14 days (area under the curve (±95% confidence interval), P-value, sensitivity, specificity; 0.72 (0.54-0.90), 0.040, 60.0%, 73.3%), 21 days (0.71 (0.52-0.90), 0.049, 66.7%, 73.3%) and 28 days (0.77 (0.59-0.96), 0.017, 69.2%, 69.2%) but not at 7 days. Intestinal microbiota did not differ between BPD subjects and controls.ConclusionFecal VOC profiles of infants developing BPD could be differentiated from controls at postnatal day 14, 21, and 28. VOC differences could not be directed to intestinal microbiota alterations but presumably reflect local and systemic metabolic and inflammatory pathways associated with BPD.

Risk Factors for Necrotizing Enterocolitis: A Prospective Multicenter Case-Control Study

BACKGROUND

The identification of independent clinical risk factors for necrotizing enterocolitis (NEC) may contribute to early selection of infants at risk, allowing for the development of targeted strategies aimed at the prevention of NEC.

OBJECTIVE

The objective of this study was to identify independent risk factors contributing to the development of NEC in a large multicenter cohort.

METHODS

This prospective cohort study was performed in 9 neonatal intensive care units. Infants born at a gestational age ≤30 weeks were included. Demographic and clinical data were collected daily until day 28 postnatally. Factors predictive of the development of NEC were identified using univariate and multivariable analyses in a 1: 5 matched case-control cohort.

RESULTS

In total, 843 infants (56 NEC cases) were included in this study. In the case-control cohort, univariate analysis identified sepsis prior to the onset of NEC and formula feeding to be associated with an increased risk of developing NEC, whereas the administration of antibiotics directly postpartum was inversely associated with NEC. In a multivariable logistic regression model, enteral feeding type and the number of days parenterally fed remained statistically significantly associated with NEC, whereas the administration of antibiotics directly after birth was associated with a lower risk of developing NEC.

CONCLUSIONS

Formula feeding and prolonged (duration of) parenteral feeding were associated with an increased risk of NEC. Contrary to expectations, the initiation of treatment with antibiotics within 24 h after birth was inversely associated with NEC.

Effects of Sampling Conditions and Environmental Factors on Fecal Volatile Organic Compound Analysis by an Electronic Nose Device

Prior to implementation of volatile organic compound (VOC) analysis in clinical practice, substantial challenges, including methodological, biological and analytical difficulties are faced. The aim of this study was to evaluate the influence of several sampling conditions and environmental factors on fecal VOC profiles, analyzed by an electronic nose (eNose). Effects of fecal sample mass, water content, duration of storage at room temperature, fecal sample temperature, number of freeze-thaw cycles and effect of sampling method (rectal swabs vs. fecal samples) on VOC profiles were assessed by analysis of totally 725 fecal samples by means of an eNose (Cyranose320®). Furthermore, fecal VOC profiles of totally 1285 fecal samples from 71 infants born at three different hospitals were compared to assess the influence of center of origin on VOC outcome. We observed that all analyzed variables significantly influenced fecal VOC composition. It was feasible to capture a VOC profile using rectal swabs, although this differed significantly from fecal VOC profiles of similar subjects. In addition, 1285 fecal VOC-profiles could significantly be discriminated based on center of birth. In conclusion, standardization of methodology is necessary before fecal VOC analysis can live up to its potential as diagnostic tool in clinical practice.

Fully automated predictive intelligent control of oxygenation (PRICO) in resuscitation and ventilation of preterm lambs

BACKGROUND

Hyperoxia and hypoxia influence morbidity and mortality of preterm infants. Automated closed-loop control of the fraction of inspired oxygen (FiO(2)) has been shown to facilitate oxygen supplementation in the neonatal intensive care unit (NICU), but has not yet been tested during preterm resuscitation. We hypothesized that fully automated FiO(2) control based on predefined oxygen saturation (SpO(2)) targets was applicable in both preterm resuscitation and ventilation.

METHODS

Twenty-two preterm lambs were operatively delivered and intubated in a modified EXIT procedure. They were randomized to receive standardized resuscitation with either automated or manual FiO(2) control, targeting SpO(2) according to the Dawson curve in the first 10 min and SpO(2) 90-95% hereafter. Automated FiO(2) control also was applied during surfactant replacement therapy and subsequent ventilation.

RESULTS

Time within target range did not differ significantly between manual and automated FiO(2) control during resuscitation, however automated FiO(2) control significantly avoided hyperoxia. Automated FiO(2) control was feasible during surfactant replacement and kept SpO(2) within target range significantly better than manual control during subsequent ventilation.

CONCLUSION

In our model, fully automated FiO(2) control was feasible in rapidly changing physiologic conditions during postnatal resuscitation and prevented hyperoxia. We conclude that closed loop FiO(2) control is a promising tool for the delivery room.

Prevalence of systemic air-embolism after prolonged cardiopulmonary resuscitation in newborns: A pilot study

BACKGROUND

Chest compressions (CC) during cardiopulmonary resuscitation (CPR) are the cornerstone of adult CPR protocols and are meant to restore circulation and improve outcome. Although adverse effects such as air-embolisms have been reported, these are rare and considered to be outweighed by beneficial effect. In newborns, however, the lung tissue is more fragile. Thus, the high intra-thoracic pressures resulting from CC may make the newborns more vulnerable for air-embolisms.

OBJECTIVES

We studied the postmortem prevalence of air-embolism in neonates that have received CPR.

METHODS

Prospective cohort analysis of newborns receiving CC during CPR. CPR was performed by trained staff according to ILCOR guidelines, in a tertiary hospital. Air-embolisms were sought after using CT/MRI and autopsy.

RESULTS

During a 61/2 year period (2007-2014), n = 56 newborns received CC. Newborns were resuscitated following severe perinatal hypoxia, or due to complications during NICU treatment. In n = 14 (25.0%) circulation could not be restored (mean CPR duration: 32.7 ± 15.2 min). Post-mortem CT/MRI was performed in n = 9, of whom n = 8 (88.9%) had air-embolisms. Autopsy was performed in n = 9. The air-embolisms could not be retraced on autopsy except for n = 1 patient. In patients with CPR resulting in restored circulation (n = 42), no CT or MRI was performed for comparison due to radiation and/or hemodynamic instability. Cerebral ultrasound could not identify or exclude air-embolisms in this subgroup.

CONCLUSIONS

Post-mortem CT after prolonged resuscitation showed a high prevalence of intravascular air-embolism. Autopsy was not suited to detect air-embolism. The clinical importance of air-embolisms on the lethal outcome needs further research.

Effects of less-invasive surfactant administration on oxygenation, pulmonary surfactant distribution, and lung compliance in spontaneously breathing preterm lambs

BACKGROUND

A new technique was proposed to administer surfactant to spontaneous breathing preterm infants by placing a thin catheter through the vocal cords. This technique was not studied with respect to oxygenation, gas exchange, surfactant distribution, and lung mechanics. We tested the technique of less-invasive surfactant administration (LISA) in a spontaneous breathing preterm lamb model.

METHODS

Preterm lambs (n = 12) of 133-134 d gestational age were randomized to the following three groups: (i) continuous positive airway pressure (CPAP) only, (ii) CPAP + LISA, and (iii) intubation and mechanical ventilation with surfactant administration. Surfactant was labeled with samarium oxide. During the next 180 min, blood gas analyses were performed. Postmortem, lungs were removed and surfactant distribution was assessed, and pressure-volume curves were performed.

RESULTS

Pao2 in the LISA-treated lambs was significantly higher than in the lambs that exclusively received CPAP. Moreover, Pao2 values were similar between the LISA-treated and the intubated lambs. Overall, surfactant deposition was less in the LISA lambs, with significantly less surfactant distributed to the right upper lobe. Lung compliance was better in the intubated lambs compared with the LISA-treated lambs, although this did not reach significance.

CONCLUSION

LISA improved oxygenation, similar to conventional surfactant application techniques, despite lower surfactant deposition and lung compliance.

Topography of maturational changes in EEG burst spectral power of the preterm infant with a normal follow-up at 2 years of age

OBJECTIVE

To quantify the electroencephalography (EEG) burst frequency spectrum of preterm infants by automated analysis and to describe the topography of maturational change in spectral parameters.

METHODS

Eighteen preterm infants <32weeks gestation and normal neurological follow-up at 2years underwent weekly 4-h EEG recordings (10-20 system). The recordings (n=77) represent a large variability in postmenstrual age (PMA, 28-36weeks). We applied an automated burst detection algorithm and performed spectral analysis. The frequency spectrum was divided into δ1 (0.5-1Hz), δ2 (1-4Hz), θ (4-8Hz), α (8-13Hz) and β (13-30Hz) bands. Spectral parameters were evaluated as a function of PMA by regression analysis. Results were interpolated and topographically visualised.

RESULTS

The majority of spectral parameters show significant change with PMA. Highest correlation is found for δ and θ band. Absolute band powers decrease with increasing PMA, while relative α and β powers increase. Maturational change is largest in frontal and temporal region.

CONCLUSIONS

Topographic distribution of maturational changes in spectral parameters corresponds with studies showing ongoing gyration and postnatal white matter maturation in frontal and temporal lobes.

SIGNIFICANCE

Computer analysis of EEG may allow objective and reproducible analysis for long-term prognosis and/or stratification of clinical treatment.

Multi-channel amplitude-integrated EEG characteristics in preterm infants with a normal neurodevelopment at two years of corrected age

AIM

To analyze quantitatively multi-channel amplitude-integrated EEG (aEEG) characteristics and assess regional differences.

METHODS

We investigated 40 preterm infants (postmenstrual age, PMA: range 27-37 weeks) with normal follow-up at 24 months of age, at a median postnatal age of 8 days using 4-h EEG recordings according to the international 10-20 system reduced montage. Nine (3 transverse and 6 longitudinal) channels were selected and converted to aEEG registrations. For each aEEG registration, lower margin amplitude (LMA), upper margin amplitude (UMA) and bandwidth (UMA-LMA) were calculated.

RESULTS

In all channels PMA and LMA showed strong positive correlations. Below 32 weeks of PMA, LMA was ≤5μV. Linear regression analysis showed a maximum LMA difference between channels of approximately 2 and 1μV at 27 and 37 weeks of PMA, respectively. The lowest are LMA values in the occipital channel and the highest values are in centro-occipital channels. In the frontal, centro-temporal and centro-occipital channels, UMA and bandwidth changed with PMA. No differences in LMA, UMA and bandwidth were found between hemispheres. Skewness of LMA values strongly correlated with PMA, positive skewness indicating an immature brain (PMA≤32 weeks) and negative skewness a maturing (PMA>32 weeks) brain.

CONCLUSIONS

We detected symmetric increase of aEEG characteristics, indicating symmetric brain maturation of the left and right hemispheres. Our findings demonstrate the clinical potential of computer-assisted analyses of aEEG recordings in detecting maturational features which are not readily identified visually. This may provide an objective and reproducible method for assessing brain maturation and long-term prognosis.

Maturational changes in automated EEG spectral power analysis in preterm infants

Our study aimed at automated power spectral analysis of the EEG in preterm infants to identify changes of spectral measures with maturation. Weekly (10-20 montage) 4-h EEG recordings were performed in 18 preterm infants with GA <32 wk and normal neurological follow-up at 2 y, resulting in 79 recordings studied from 27(+4) to 36(+3) wk of postmenstrual age (PMA, GA + postnatal age). Automated spectral analysis was performed on 4-h EEG recordings. The frequency spectrum was divided in delta 1 (0.5-1 Hz), delta 2 (1-4 Hz), theta (4-8 Hz), alpha (8-13 Hz), and beta (13-30 Hz) band. Absolute and relative power of each frequency band and spectral edge frequency were calculated. Maturational changes in spectral measures were observed most clearly in the centrotemporal channels. With advancing PMA, absolute powers of delta 1 to 2 and theta decreased. With advancing PMA, relative power of delta 1 decreased and relative powers of alpha and beta increased, respectively. In conclusion, with maturation, spectral analysis of the EEG showed a significant shift from the lower to the higher frequencies. Computer analysis of EEG will allow an objective and reproducible analysis for long-term prognosis and/or stratification of clinical treatment.

Automatic burst detection for the EEG of the preterm infant

To aid with prognosis and stratification of clinical treatment for preterm infants, a method for automated detection of bursts, interburst-intervals (IBIs) and continuous patterns in the electroencephalogram (EEG) is developed. Results are evaluated for preterm infants with normal neurological follow-up at 2 years. The detection algorithm (MATLAB®) for burst, IBI and continuous pattern is based on selection by amplitude, time span, number of channels and numbers of active electrodes. Annotations of two neurophysiologists were used to determine threshold values. The training set consisted of EEG recordings of four preterm infants with postmenstrual age (PMA, gestational age + postnatal age) of 29-34 weeks. Optimal threshold values were based on overall highest sensitivity. For evaluation, both observers verified detections in an independent dataset of four EEG recordings with comparable PMA. Algorithm performance was assessed by calculation of sensitivity and positive predictive value. The results of algorithm evaluation are as follows: sensitivity values of 90% ± 6%, 80% ± 9% and 97% ± 5% for burst, IBI and continuous patterns, respectively. Corresponding positive predictive values were 88% ± 8%, 96% ± 3% and 85% ± 15%, respectively. In conclusion, the algorithm showed high sensitivity and positive predictive values for bursts, IBIs and continuous patterns in preterm EEG. Computer-assisted analysis of EEG may allow objective and reproducible analysis for clinical treatment.

Quantitative analysis of maturational changes in EEG background activity in very preterm infants with a normal neurodevelopment at 1 year of age

BACKGROUND

The electroencephalographic (EEG) background pattern of preterm infants changes with postmenstrual age (PMA) from discontinuous activity to continuous activity. However, changes in discontinuity have been investigated by visual analysis only.

AIM

To investigate the maturational changes in EEG discontinuity in healthy preterm infants using an automated EEG detection algorithm.

STUDY DESIGN

Weekly 4h EEG recordings were performed in preterm infants with a gestational age (GA)<32weeks and normal neurological follow-up at 1year. The channel C3-C4 was analyzed using an algorithm which automatically detects periods of EEG inactivity (interburst intervals). The interburst-burst ratio (IBR, percentage of EEG inactivity during a moving time window of 600s) and mean length of the interburst intervals were calculated. Using the IBR, discontinuous background activity (periods with high IBR) and continuous background activity (periods with low IBR) were automatically detected and their mean length during each recording was calculated. Data were analyzed with regression and multivariate analysis.

RESULTS

79 recordings were performed in 18 infants. All recordings showed a cyclical pattern in EEG discontinuity. With advancing PMA, IBR (R(2)=0.64; p<0.001), interburst interval length (R(2)=0.43; p<0.001) and length of discontinuous activity (R(2)=0.38; p<0.001) decreased, while continuous activity increased (R(2)=0.50; p<0.001). Multivariate analysis showed that all EEG discontinuity parameters were equally influenced by GA and postnatal age.

CONCLUSION

Analyzing EEG background activity in preterm infants is feasible with an automated algorithm and shows maturational changes of several EEG derived parameters. The cyclical pattern in IBR suggests brain organisation in preterm infant.

Quantitative analysis of amplitude-integrated electroencephalogram patterns in stable preterm infants, with normal neurological development at one year

BACKGROUND

The amplitude-integrated EEG (aEEG) is feasible for monitoring cerebral activity in preterm infants. However, quantitative data on normal patterns in these infants are limited.

OBJECTIVE

To study maturational aEEG changes in a cohort of stable preterm infants by automated quantification.

METHODS

In a cohort of stable preterm infants with gestational age (GA) <32 weeks and normal neurological follow-up at 1 year, weekly 4 h EEG recordings were performed. aEEG traces were obtained from channel C(3)-C(4). The upper margin amplitude (UMA), lower margin amplitude (LMA) and bandwidth (BW) were quantitatively calculated using an expert software system. In addition, the relative duration of discontinuous background pattern (discontinuous background defined as activity with LMA <5 microV, expressed as DC-%) was calculated.

RESULTS

79 aEEG recordings (4-6 recordings/infant) were obtained in 18 infants. Analysis of the first week recordings demonstrated a strong positive correlation between GA and LMA, while DC-% decreased significantly. Longitudinally, all infants showed increase of LMA. Multivariate analysis showed that GA and postnatal age (PA) both contributed independently and equally to LMA and DC-%. We found a strong correlation between postmenstrual age (GA + PA) and LMA and DC-%, respectively.

CONCLUSION

To our knowledge, this is the first study where aEEG development was studied by automated quantification of aEEG characteristics in a cohort of stable preterm infants with a normal neurological development at 1 year of age. LMA and DC-% are simple quantitative measures of neurophysiologic development and may be used to evaluate neurodevelopment in infants.

[Two neonates with congenital aniridia: the necessity of genetic investigation]

Two female neonates were diagnosed post partum with bilateral aniridia. The first patient had the familial form, caused by a point mutation in the paired box 6 (PAX6) gene. The second patient had a sporadic aniridia caused by a de novo microdeletion involving both the PAX6 gene as well as the Wilms tumour suppressor-I (WT1) gene. This made screening for the presence of a Wilms tumour necessary. The second patient died several months after birth, due to respiratory insufficiency. Aniridia is a rare developmental disorder of the eye, with absence of most of the iris tissue, caused by an abnormality in the PAX6 gene on chromosome 11p13. Familial aniridia is usually due to a point mutation of the PAX6 gene, which causes solely ocular abnormalities. Sporadic aniridia is caused by a de novo deletion or microdeletion of chromosome 11p13, which affects not only the PAX6 gene but also the adjacent WT1 gene. In these patients, the Wilms tumour, aniridia, genitourinary anomalies, and mental retardation (WAGR) syndrome can be present, and screening for a Wilms tumour is indicated. Unless previous investigation of a family member has demonstrated the WT1 gene to be normal, chromosome studies should always be performed in patients with aniridia.

Amplitude-integrated electroencephalographic changes in a newborn induced by overdose of morphine and corrected with naloxone

The amplitude-integrated electroencephalogram (aEEG) is a useful tool to assess brain function after perinatal asphyxia in term infants. We report a full-term newborn with moderate perinatal asphyxia, who accidentally received an overdose of morphine (5000 microg/kg). The overdose of morphine resulted in a clear and immediate change of aEEG background activity from a continuous (C) to discontinuous (DC) background pattern. After administration of naloxone, the background activity restored immediately to continuous background pattern. The aEEG was used to monitor the stepwise reduction in continuous naloxone infusion.

CONCLUSION

An overdose of morphine leads to clear and immediate changes in aEEG which restore after naloxone treatment. The aEEG can be used to monitor naloxone infusion.

Breath condenser coatings affect measurement of biomarkers in exhaled breath condensate

Exhaled breath condensate collection is not yet standardised and biomarker measurements are often close to lower detection limits. In the current study, it was hypothesised that adhesive properties of different condenser coatings interfere with measurements of eicosanoids and proteins in breath condensate. In vitro, condensate was derived from a collection model using two test solutions (8-isoprostane and albumin) and five condenser coatings (silicone, glass, aluminium, polypropylene and Teflon). In vivo, condensate was collected using these five coatings and the EcoScreen condenser to measure 8-isoprostane, and three coatings (silicone, glass, EcoScreen) to measure albumin. In vitro, silicone and glass coatings had significantly higher albumin recovery compared with the other coatings. A similar trend was observed for 8-isoprostane recovery. In vivo, median (interquartile range) 8-isoprostane concentrations were significantly higher using silicone (9.2 (18.8) pg.mL(-1)) or glass (3.0 (4.5) pg.mL(-1)) coating, compared with aluminium (0.5 (2.4) pg.mL(-1)), polypropylene (0.5 (0.5) pg.mL(-1)), Teflon (0.5 (0.0) pg.mL(-1)), and EcoScreen (0.5 (2.0) pg.mL(-1)). Albumin in vivo was mainly detectable using glass coating. In conclusion, a condenser with silicone or glass coating is more efficient for measurement of 8-isoprostane or albumin in exhaled breath condensate, than EcoScreen, aluminium, polypropylene or Teflon. Guidelines for exhaled breath condensate standardisation should include the most valid condenser coating to measure a specific biomarker.