Heart rate variability and extubation readiness in extremely preterm infants

Peri-extubation settings in preterm neonates: a systematic review and meta-analysis

OBJECTIVE

To systematically review: 1) peri-extubation settings; and 2) association between peri-extubation settings and outcomes in preterm neonates.

STUDY DESIGN

In this systematic review, studies were eligible if they reported patient-data on peri-extubation settings (objective 1) and/or evaluated peri-extubation levels in relation to clinical outcomes (objective 2). Data were meta-analyzed when appropriate using random-effects model.

RESULTS

Of 9681 titles, 376 full-texts were reviewed and 101 included. The pooled means of peri-extubation settings were summarized. For objective 2, three experimental studies were identified comparing post-extubation CPAP levels. Meta-analyses revealed lower odds for treatment failure [pooled OR 0.46 (95% CI 0.27-0.76); 3 studies, 255 participants] but not for re-intubation [pooled OR 0.66 (0.22-1.97); 3 studies, 255 participants] with higher vs. lower CPAP.

CONCLUSIONS

Summary of peri-extubation settings may guide clinicians in their own practices. Higher CPAP levels may reduce extubation failure, but more data on peri-extubation settings that optimize outcomes are needed.

Predictors of successful extubation from volume-targeted ventilation in extremely preterm neonates

OBJECTIVE

To identify variables associated with extubation success in extremely preterm neonates extubated from invasive volume-targeted ventilation.

STUDY DESIGN

We retrospectively evaluated 84 neonates ≤28 weeks' gestational age, on their first elective extubation. The primary outcome of successful extubation was defined as non-reintubation within seven days. We used multivariate logistic regression analysis.

RESULTS

We identified 58 (69%) neonates (mean gestational age of 26.5 ± 1.4 weeks, birthweight 921 ± 217 g) who met the primary outcome. Female sex (OR 1.15, 95% CI 1.01-9.10), higher pre-extubation weight (OR 1.29, 95% CI 1.05-1.59), and pH (OR 2.54, 95% CI 1.54-4.19), and lower pre-extubation mean airway pressure (MAP) (OR 0.49, 95% CI 0.33-0.73) were associated with successful extubation.

CONCLUSIONS

In preterm neonates, female sex, higher pre-extubation weight and pH, and lower pre-extubation MAP were predictors of successful extubation from volume-targeted ventilation. Evaluation of these variables will likely assist clinicians in selecting the optimal time for extubation in such vulnerable neonates.

Defining predictors for successful mechanical ventilation weaning, using a data-mining process and artificial intelligence

Mechanical ventilation weaning within intensive care units (ICU) is a difficult process, while crucial when considering its impact on morbidity and mortality. Failed extubation and prolonged mechanical ventilation both carry a significant risk of adverse events. We aimed to determine predictive factors of extubation success using data-mining and artificial intelligence. A prospective physiological and biomedical signal data warehousing project. A 21-beds medical Intensive Care Unit of a University Hospital. Adult patients undergoing weaning from mechanical ventilation. Hemodynamic and respiratory parameters of mechanically ventilated patients were prospectively collected and combined with clinical outcome data. One hundred and eight patients were included, for 135 spontaneous breathing trials (SBT) allowing to identify physiological parameters either measured before or during the trial and considered as predictive for extubation success. The Early-Warning Score Oxygen (EWSO2) enables to discriminate patients deemed to succeed extubation, at 72-h and 7-days. Cut-off values for EWSO2 (AUC = 0.80; Se = 0.75; Sp = 0.76), mean arterial pressure and heart-rate variability parameters were determined. A predictive model for extubation success was established including body-mass index (BMI) on inclusion, occlusion pressure at 0,1 s. (P0.1) and heart-rate analysis parameters (LF/HF) both measured before SBT, and heart rate during SBT (global performance 62%; 83%). The data-mining process enabled to detect independent predictive factors for extubation success and to develop a dynamic predictive model using artificial intelligence. Such predictive tools may help clinicians to better discriminate patients deemed to succeed extubation and thus improve clinical performance.

Predictors of extubation failure in newborns: a systematic review and meta-analysis

Extubation failure (EF) is a significant concern in mechanically ventilated newborns, and predicting its occurrence is an ongoing area of research. To investigate the predictors of EF in newborns undergoing planned extubation, we conducted a systematic review and meta-analysis. A systematic literature search was conducted in PubMed, Web of Science, Embase, and Cochrane Library for studies published in English from the inception of each database to March 2023. The PRISMA guidelines were followed in all phases of this systematic review. The Risk of Bias Assessment for Nonrandomized Studies tool was used to assess methodological quality. Thirty-four studies were included, 10 of which were overall low risk of bias, 15 of moderate risk of bias, and 9 of high risk of bias. The studies reported 43 possible predictors in six broad categories (intrinsic factors; maternal factors; diseases and adverse conditions of the newborn; treatment of the newborn; characteristics before and after extubation; and clinical scores and composite indicators). Through a qualitative synthesis of 43 predictors and a quantitative meta-analysis of 19 factors, we identified five definite factors, eight possible factors, and 22 unclear factors related to EF. Definite factors included gestational age, sepsis, pre-extubation pH, pre-extubation FiO2, and respiratory severity score. Possible factors included age at extubation, anemia, inotropic use, mean airway pressure, pre-extubation PCO2, mechanical ventilation duration, Apgar score, and spontaneous breathing trial. With only a few high-quality studies currently available, well-designed and more extensive prospective studies investigating the predictors affecting EF are still needed. In the future, it will be important to explore the possibility of combining multiple predictors or assessment tools to enhance the accuracy of predicting extubation outcomes in clinical practice.

Optimal timing of extubation in preterm infants

In neonatal intensive care, endotracheal intubation is usually performed as an urgent or semi-urgent procedure in infants with critical or unstable conditions related to progressive respiratory failure. Extubation is not. Patients undergoing extubation are typically stable, with improved respiratory function. The key elements to facilitating extubation are to recognize improvement in respiratory status, promote weaning of mechanical ventilation, and accurately identify readiness for removal of the endotracheal tube. Therefore, extubation should be a planned and well-organized procedure. In this review, we will appraise the evidence for existing predictors of extubation readiness and provide patient-specific, pathophysiology-derived strategies to optimize the timing and success of extubation in neonates, with a focus on extremely preterm infants.

Development and validation of a prediction model for evaluating extubation readiness in preterm infants

Successful early extubation has advantages not only in terms of short-term respiratory morbidities and survival but also in terms of long-term neurodevelopmental outcomes in preterm infants. However, no consensus exists regarding the optimal protocol or guidelines for extubation readiness in preterm infants. Therefore, the decision to extubate preterm infants was almost entirely at the attending physician's discretion. We identified robust and quantitative predictors of success or failure of the first planned extubation attempt before 36 weeks of post-menstrual age in preterm infants (<32 weeks gestational age) and developed a prediction model for evaluating extubation readiness using these predictors. Extubation success was defined as the absence of reintubation within 72 h after extubation. This observational cohort study used data from preterm infants admitted to the neonatal intensive care unit of Seoul National University Bundang Hospital in South Korea between July 2003 and June 2019 to identify predictors and develop and test a predictive model for extubation readiness. Data from preterm infants included in the Medical Informative Medicine for Intensive Care (MIMIC-III) database between 2001 and 2008 were used for external validation. From a machine learning model using predictors such as demographics, periodic vital signs, ventilator settings, and respiratory indices, the area under the receiver operating characteristic curve and average precision of our model were 0.805 (95% confidence interval [CI], 0.802-0.809) and 0.917, respectively in the internal validation and 0.715 (95% CI, 0.713-0.717) and 0.838, respectively in the external validation. Our prediction model (NExt-Predictor) demonstrated high performance in assessing extubation readiness in both internal and external validations.

Predictive factors for extubation success in very low and extremely low birth weight preterm infants

Background

Although invasive mechanical ventilation (IMV) has contributed to the survival of preterm infants with extremely low birth weight (ELBW), it is also associated with unsatisfactory clinical outcomes when used for prolonged periods. This study aimed to identify factors that may be decisive for extubation success in very low birth weight (VLBW) and extremely low birth weight (ELBW) preterm infants.

Methods

The cohort study included preterm infants with gestational age (GA) <36 weeks, birth weight (BW) <1500 grams who underwent IMV, born between 2015 and 2018. The infants were allocated into two groups: extubation success (SG) or failure (FG). A stepwise logistic regression model was created to determine variables associated with successful extubation.

Results

Eighty-three preterm infants were included. GA and post-extubation arterial partial pressure of carbon dioxide (PaCO2) were predictive of extubation success. Infants from FG had lower GA and BW, while those from SG had higher weight at extubation and lower post-extubation PaCO2.

Discussion

Although we found post-extubation PaCO2 as an extubation success predictor, which is a variable representative of the moment after the primary outcome, this does not diminish its clinical relevance since extubation does not implicate in ET removal only; it also involves all the aspects that take place within a specified period (72 hours) after the planned event.

Conclusion

GA and post-extubation PaCO2 were predictors for extubation success in VLBW and ELBW preterm infants. Infants who experienced extubation failure had lower birth weight and higher FiO2 prior to extubation.

Respiratory Management of the Preterm Infant: Supporting Evidence-Based Practice at the Bedside

Extremely preterm infants frequently require some form of respiratory assistance to facilitate the cardiopulmonary transition that occurs in the first hours of life. Current resuscitation guidelines identify as a primary determinant of overall newborn survival the establishment, immediately after birth, of adequate lung inflation and ventilation to ensure an adequate functional residual capacity. Any respiratory support provided, however, is an important contributing factor to the development of bronchopulmonary dysplasia. The risks correlated to invasive ventilatory techniques increase inversely with gestational age. Preterm infants are born at an early stage of lung development and are more susceptible to lung injury deriving from mechanical ventilation. Any approach aiming to reduce the global burden of preterm lung disease must implement lung-protective ventilation strategies that begin from the newborn’s first breaths in the delivery room. Neonatologists today must be able to manage both invasive and noninvasive forms of respiratory assistance to treat a spectrum of lung diseases ranging from acute to chronic conditions. We searched PubMed for articles on preterm infant respiratory assistance. Our narrative review provides an evidence-based overview on the respiratory management of preterm infants, especially in the acute phase of neonatal respiratory distress syndrome, starting from the delivery room and continuing in the neonatal intensive care unit, including a section regarding exogenous surfactant therapy.

Autonomic markers of extubation readiness in premature infants

BACKGROUND

In premature infants, extubation failure is common and difficult to predict. Heart rate variability (HRV) is a marker of autonomic tone. Our aim is to test the hypothesis that autonomic impairment is associated with extubation readiness.

METHODS

Retrospective study of 89 infants <28 weeks. HRV metrics 24 h prior to extubation were compared for those with and without extubation success within 72 h. Receiver-operating curve analysis was conducted to determine the predictive ability of each metric, and a predictive model was created.

RESULTS

Seventy-three percent were successfully extubated. The success group had significantly lower oxygen requirement, higher sympathetic HRV metrics, and a lower parasympathetic HRV metric. α₁ (measure of autocorrelation, related to sympathetic tone) was the best predictor of success-area under the curve (AUC) of .73 (p = 0.001), and incorporated into a predictive model had an AUC of 0.81 (p < 0.0001)-sensitivity of 81% and specificity of 78%.

CONCLUSIONS

Extubation success is associated with HRV. We show an autonomic imbalance with low sympathetic and elevated parasympathetic tone in those who failed. α₁, a marker of sympathetic tone, was noted to be the best predictor of extubation success especially when incorporated into a clinical model.

IMPACT

This article depicts autonomic markers predictive of extubation success. We depict an autonomic imbalance in those who fail extubation with heightened parasympathetic and blunted sympathetic signal. We describe a predictive model for extubation success with a sensitivity of 81% and specificity of 78%.

Prediction of extubation failure among low birthweight neonates using machine learning

OBJECTIVE

To develop machine learning models predicting extubation failure in low birthweight neonates using large amounts of clinical data.

STUDY DESIGN

Retrospective cohort study using MIMIC-III, a large single-center, open-source clinical dataset. Logistic regression and boosted-tree (XGBoost) models using demographics, medications, and vital sign and ventilatory data were developed to predict extubation failure, defined as reintubation within 7 days.

RESULTS

1348 low birthweight (≤2500 g) neonates who received mechanical ventilation within the first 7 days were included, of which 350 (26%) failed a trial of extubation. The best-performing model was a boosted-tree model incorporating demographics, vital signs, ventilator parameters, and medications (AUROC 0.82). The most important features were birthweight, last FiO2, average mean airway pressure, caffeine use, and gestational age.

CONCLUSIONS

Machine learning models identified low birthweight ventilated neonates at risk for extubation failure. These models will need to be validated across multiple centers to determine generalizability of this tool.

Dynamic touch induces autonomic changes in preterm infants as measured by changes in heart rate variability

Preterm birth significantly increases the risk of developing various long-term health problems and developmental disabilities. While touch is a crucial component of many perinatal care strategies, the neurobiological underpinnings are rarely considered. C-tactile fibers (CTs) are unmyelinated nerve fibers that are activated by low-force, dynamic touch. Touch directed specifically at CTs activates the posterior insular cortex, consistent with an interoceptive function, and has been shown to reduce heart rate and increase oxygen saturation. The current research compared the effect of five minutes of CT optimal velocity stroking touch versus five minutes of static touch on autonomic markers of preterm infants between 28 and 37 weeks gestational age. CT touch induces a higher increase in heart rate variability metrics related to the parasympathetic system, which persisted for a 5-minute post-touch period. Conversely, there was no such increase in infants receiving static touch. The present findings confirmed that CTs signal the affective quality of nurturing touch, thereby arguing an additional neurobiological substrate for the evident valuable impacts of neonatal tactile interventions and improving the effectiveness of such interventions.

Weaning and extubation from neonatal mechanical ventilation: an evidenced-based review

Mechanical ventilation is a lifesaving treatment used to treat critical neonatal patients. It facilitates gas exchange, oxygenation, and CO2 removal. Despite advances in non-invasive ventilatory support methods in neonates, invasive ventilation (i.e., ventilation via an endotracheal tube) is still a standard treatment in NICUs. This ventilation approach may cause injury despite its advantages, especially in preterm neonates. Therefore, it is recommended that neonatologists consider weaning neonates from invasive mechanical ventilation as soon as possible. This review examines the steps required for the neonate's appropriate weaning and safe extubation from mechanical ventilation.

Cardiorespiratory measures shortly after extubation and extubation outcomes in extremely preterm infants

BACKGROUND

Nasal continuous positive airway pressure, nasal intermittent positive pressure ventilation, and non-invasive neurally adjusted ventilatory assist are modes of non-invasive respiratory support. The objective was to investigate if cardiorespiratory measures performed shortly after extubation are associated with extubation outcomes and predictors of extubation success.

METHODS

Randomized crossover trial of infants with birth weight (BW) ≤ 1250 g undergoing their first extubation. Shortly after extubation, electrocardiogram and electrical activity of the diaphragm (Edi) were recorded during 40 min on each mode. Measures of heart rate variability (HRV), diaphragmatic activity (Edi area, breath area and amplitude), and respiratory variability (RV) were computed on each mode and compared between infants with extubation success or failure (reintubation ≤ 7 days).

RESULTS

Twenty-three extremely preterm infants with median [IQR] gestational age 25.9 weeks [25.2-26.4] and BW 760 g [595-900] were included: 14 success and 9 failures. There were significant differences for HRV (very low-frequency power and sample entropy) and RV parameters (breath areas, amplitudes and expiratory times) between groups, with moderate strength (0.75-0.80 areas under ROC curves) in predicting success. Diaphragmatic activity measures were similar between groups.

CONCLUSIONS

In extremely preterm infants receiving non-invasive respiratory support shortly after extubation, several cardiorespiratory variability parameters were associated with successful extubation with moderate predictive accuracy.

IMPACT

Measures of cardiorespiratory variability, performed in extremely preterm infants while receiving NCPAP, NIPPV, and NIV-NAVA shortly after extubation, were significantly different between patients that succeeded or failed extubation. Cardiorespiratory variability measures had a moderate predictive accuracy for extubation success and can be potentially used as biomarkers, in recently extubated infants. Future investigations in this population may also consider including cardiorespiratory variability measures when assessing types of post-extubation respiratory support and promote individualized care.

Predictors of extubation success: a population-based study of neonates below a gestational age of 26 weeks

OBJECTIVE

The aim of the study was to investigate first extubation attempts among extremely premature (EP) infants and to explore factors that may increase the quality of clinical judgement of extubation readiness.

DESIGN AND METHOD

A population-based study was conducted to explore first extubation attempts for EP infants born before a gestational age (GA) of 26 weeks in Norway between 1 January 2013 and 31 December 2018. Eligible infants were identified via the Norwegian Neonatal Network database. The primary outcome was successful extubation, defined as no reintubation within 72 hours after extubation.

RESULTS

Among 482 eligible infants, 316 first extubation attempts were identified. Overall, 173 (55%) infants were successfully extubated, whereas the first attempt failed in 143 (45%) infants. A total of 261 (83%) infants were extubated from conventional ventilation (CV), and 55 (17%) infants were extubated from high-frequency oscillatory ventilation (HFOV). In extubation from CV, pre-extubation fraction of inspired oxygen (FiO₂) ≤0.35, higher Apgar score, higher GA, female sex and higher postnatal age were important predictors of successful extubation. In extubation from HFOV, a pre-extubation FiO₂ level ≤0.35 was a relevant predictor of successful extubation.

CONCLUSIONS

The correct timing of extubation in EP infants is important. In this national cohort, 55% of the first extubation attempts were successful. Our results suggest that additional emphasis on oxygen requirement, sex and general condition at birth may further increase extubation success when clinicians are about to extubate EP infants for the first time.

Neonatal heart rate variability: a contemporary scoping review of analysis methods and clinical applications

BACKGROUND

Neonatal heart rate variability (HRV) is widely used as a research tool. However, HRV calculation methods are highly variable making it difficult for comparisons between studies.

OBJECTIVES

To describe the different types of investigations where neonatal HRV was used, study characteristics, and types of analyses performed.

ELIGIBILITY CRITERIA

Human neonates ≤1 month of corrected age.

SOURCES OF EVIDENCE

A protocol and search strategy of the literature was developed in collaboration with the McGill University Health Center's librarians and articles were obtained from searches in the Biosis, Cochrane, Embase, Medline and Web of Science databases published between 1 January 2000 and 1 July 2020.

CHARTING METHODS

A single reviewer screened for eligibility and data were extracted from the included articles. Information collected included the study characteristics and population, type of HRV analysis used (time domain, frequency domain, non-linear, heart rate characteristics (HRC) parameters) and clinical applications (physiological and pathological conditions, responses to various stimuli and outcome prediction).

RESULTS

Of the 286 articles included, 171 (60%) were small single centre studies (sample size <50) performed on term infants (n=136). There were 138 different types of investigations reported: physiological investigations (n=162), responses to various stimuli (n=136), pathological conditions (n=109) and outcome predictor (n=30). Frequency domain analyses were used in 210 articles (73%), followed by time domain (n=139), non-linear methods (n=74) or HRC analyses (n=25). Additionally, over 60 different measures of HRV were reported; in the frequency domain analyses alone there were 29 different ranges used for the low frequency band and 46 for the high frequency band.

CONCLUSIONS

Neonatal HRV has been used in diverse types of investigations with significant lack of consistency in analysis methods applied. Specific guidelines for HRV analyses in neonates are needed to allow for comparisons between studies.

Relationship Between the Respiratory Severity Score and Extubation Failure in Very-Low-Birth-Weight Premature Infants

Objective:

The objective of the study is to investigate the utility of the respiratory severity score (RSS), an easy-to-use, non-invasive respiratory failure assessment tool that does not require arterial blood sampling, for predicting extubation failure in very-low-birth-weight premature infants.

Methods:

Demographic characteristics, clinical course, and neonatal morbidities were retrospectively analyzed. Data were obtained from the files of infants who were admitted to our unit between February 2016 and September 2020, were born before 30 weeks’ gestation, and had a birth weight <1250 g. Extubation success was defined as no need for reintubation for 72 h after extubation. RSS and RSS/kg values before each patient’s first planned extubation were calculated. RSS values before extubation and risk factors for extubation failure were compared between infants in the successful and failed extubation groups.

Results:

Our study enrolled 142 infants who met the inclusion criteria. The extubation failure rate was 30.2% (43/142). Early gestation, low birth weight, male sex, high RSS, grade ≥3 intraventricular hemorrhage, late-onset sepsis, low weight at the time of extubation, and postmenstrual age at the time of extubation were identified as risk factors for extubation failure. In the logistic regression analysis including these risk factors, RSS/kg remained a significant risk factor, along with late-onset sepsis (OR 25.7 [95% CI: 5.70–115.76]; p<0.001). In the receiver operating characteristic analysis of RSS values, at a cutoff value of 2.13 (area under the curve: 82.5%), RSS/kg had 77% sensitivity and 78% specificity (p<0.001). The duration of mechanical ventilation and hospital stay were prolonged in infants with extubation failure. The incidence rates of stage ≥3 retinopathy of prematurity and stage ≥2 necrotizing enterocolitis were also higher.

Conclusions:

High RSS and RSS/kg values were closely associated with extubation failure and can be used as a non-invasive assessment tool to support clinical decision-making, and thus reduce the rate of extubation failure.

Cardiorespiratory effects of NIV-NAVA, NIPPV, and NCPAP shortly after extubation in extremely preterm infants: A randomized crossover trial

OBJECTIVE

Investigate the cardiorespiratory effects of noninvasive neurally adjusted ventilatory assist (NIV-NAVA), nonsynchronized nasal intermittent positive pressure ventilation (NIPPV), and nasal continuous positive airway pressure (NCPAP) shortly after extubation.

HYPOTHESIS

Types of noninvasive pressure support and the presence of synchronization may affect cardiorespiratory parameters.

STUDY DESIGN

Randomized crossover trial.

PATIENT-SUBJECT SELECTION

Infants with birth weight (BW) 1250 g or under, undergoing their first planned extubation were randomly assigned to all three modes using a computer-generated sequence.

METHODOLOGY

Electrocardiogram and electrical activity of the diaphragm (Edi) were recorded for 30 min on each mode. Analysis of heart rate variability (HRV), diaphragmatic activity (Edi area, breath area, amplitude, inspiratory and expiratory times), and respiratory variability were compared between modes.

RESULTS

Twenty-three infants had full data recordings and analysis: Median (IQR) gestational age = 25.9 weeks (25.2-26.4), BW = 760 g (595-900), and postnatal age 7 (4-19) days. There were no differences in HRV between modes. A significantly reduced Edi area and breath amplitude, and increased coefficient of variation (CV) of breath amplitude were observed during NIV-NAVA and NIPPV compared to NCPAP. A higher proportion of assisted breaths (99% vs. 51%; p < .001) provided a higher mean airway pressure (MAP; 9.4 vs. 8.2 cmH₂ O; p = .002) with lower peak inflation pressures (PIPs; 14 vs. 16 cmH₂ O; p < .001) during NIV-NAVA compared to NIPPV.

CONCLUSIONS

NIV-NAVA and NIPPV applied shortly after extubation were associated with lower respiratory efforts and higher respiratory variability. These effects were more evident for NIV-NAVA where optimal patient-ventilator synchronization provided a higher MAP with lower PIPs.

Extubation Readiness in Preterm Infants: Evaluating the Role of Monitoring Intermittent Hypoxemia

Preterm infants with respiratory distress may require mechanical ventilation which is associated with increased pulmonary morbidities. Prompt and successful extubation to noninvasive support is a pressing goal. In this communication, we show original data that increased recurring intermittent hypoxemia (IH, oxygen saturation <80%) may be associated with extubation failure at 72 h in a cohort of neonates <30 weeks gestational age. Current-generation bedside high-resolution pulse oximeters provide saturation profiles that may be of use in identifying extubation readiness and failure. A larger prospective study that utilizes intermittent hypoxemia as an adjunct predictor for extubation readiness is warranted.

Diaphragmatic activity and neural breathing variability during a 5-min endotracheal continuous positive airway pressure trial in extremely preterm infants

BACKGROUND

Extremely preterm infants are often exposed to endotracheal tube continuous positive airway pressure (ETT-CPAP) trials to assess extubation readiness. The effects of ETT-CPAP trial on their diaphragmatic activity (Edi) and breathing variability is unknown.

METHODS

Prospective observational study enrolling infants with birth weight ≤1250 g undergoing their first extubation attempt. Diaphragmatic activity, expressed as the absolute minimum (Edi min) and maximum values (Edi max), area under the Edi signal, and breath-by-breath analyses for breath areas, amplitudes, widths, and neural inspiratory and expiratory times, were analyzed during mechanical ventilation (MV) and ETT-CPAP. Neural breathing variability of each of these parameters was also calculated and compared between MV and ETT-CPAP.

RESULTS

Thirteen infants with median (interquartile range) birth weight of 800 g [610-920] and gestational age of 25.4 weeks [24.4-26.3] were included. Diaphragmatic activity significantly increased during ETT-CPAP when compared to MV:Edi max (44.2 vs. 38.1 μV), breath area (449 vs. 312 μV·s), and amplitude (10.12 vs. 7.46 μV). Neural breathing variability during ETT-CPAP was characterized by increased variability for amplitude and area under the breath, and decreased for breath time and width.

CONCLUSIONS

A 5-min ETT-CPAP in extremely preterm infants undergoing extubation imposed significant respiratory load with changes in respiratory variability.

IMPACT

ETT-CPAP trials are often used to assess extubation readiness in extremely preterm infants, but its effects upon their respiratory system are not well known. Diaphragmatic activity analysis demonstrated that these infants are able to mount an important response to a short trial. A 5-min trial imposed a significant respiratory load evidenced by increased diaphragmatic activity and changes in breathing variability. Differences in breathing variability were observed between successful and failed extubations, which should be explored further in extubation readiness investigations. This type of trial cannot be recommended for preterm infants in clinical practice until clear standards and accuracy are established.

Heart Rate Variability in the Perinatal Period: A Critical and Conceptual Review

Neonatal intensive care units (NICUs) greatly expand the use of technology. There is a need to accurately diagnose discomfort, pain, and complications, such as sepsis, mainly before they occur. While specific treatments are possible, they are often time-consuming, invasive, or painful, with detrimental effects for the development of the infant. In the last 40 years, heart rate variability (HRV) has emerged as a non-invasive measurement to monitor newborns and infants, but it still is underused. Hence, the present paper aims to review the utility of HRV in neonatology and the instruments available to assess it, showing how HRV could be an innovative tool in the years to come. When continuously monitored, HRV could help assess the baby’s overall wellbeing and neurological development to detect stress-/pain-related behaviors or pathological conditions, such as respiratory distress syndrome and hyperbilirubinemia, to address when to perform procedures to reduce the baby’s stress/pain and interventions, such as therapeutic hypothermia, and to avoid severe complications, such as sepsis and necrotizing enterocolitis, thus reducing mortality. Based on literature and previous experiences, the first step to efficiently introduce HRV in the NICUs could consist in a monitoring system that uses photoplethysmography, which is low-cost and non-invasive, and displays one or a few metrics with good clinical utility. However, to fully harness HRV clinical potential and to greatly improve neonatal care, the monitoring systems will have to rely on modern bioinformatics (machine learning and artificial intelligence algorithms), which could easily integrate infant’s HRV metrics, vital signs, and especially past history, thus elaborating models capable to efficiently monitor and predict the infant’s clinical conditions. For this reason, hospitals and institutions will have to establish tight collaborations between the obstetric, neonatal, and pediatric departments: this way, healthcare would truly improve in every stage of the perinatal period (from conception to the first years of life), since information about patients’ health would flow freely among different professionals, and high-quality research could be performed integrating the data recorded in those departments.

A predictive model for extubation readiness in extremely preterm infants

OBJECTIVE

To develop an estimator for predicting successful extubation for an individual preterm infant.

STUDY DESIGN

This was a retrospective study that included infants with birth weights ≤1250 g, who were admitted to a tertiary NICU over a 7-year period, received mechanical ventilation and had an elective extubation attempt within 60 days of age. Perinatal and periextubation characteristics were compared in the successful and failed extubation groups.

RESULTS

Of 621 screened infants, 312 were included. Extubation succeeded in 73% and failed in 27%. Adjusted factors associated with successful extubation included greater gestational age, chronologic age, pre-extubation pH and lower pre-extubation FiO₂, along with lower "peak" respiratory severity score in the first 6 h of age.

CONCLUSIONS

We used readily available demographic and clinical data to create an extubation readiness estimator that provides the probability of extubation success for an individual preterm infant (http://elasticbeanstalk-us-east-2-676799334712.s3-website.us-east-2.amazonaws.com/).

Heart Rate Variability during Periods of Low Blood Pressure as a Predictor of Short-Term Outcome in Preterms

Efficient management of low blood pressure (BP) in preterm neonates remains challenging with a considerable variability in clinical practice. The ability to assess preterm wellbeing during episodes of low BP will help to decide when and whether hypotension treatment should be initiated. This work aims to investigate the relationship between heart rate variability (HRV), BP and the short-term neurological outcome in preterm infants less than 32 weeks gestational age (GA). The predictive power of common HRV features with respect to the outcome is assessed and shown to improve when HRV is observed during episodes of low mean arterial pressure (MAP) - with a single best feature leading to an AUC of 0.87. Combining multiple features with a boosted decision tree classifier achieves an AUC of 0.97. The work presents a promising step towards the use of multimodal data in building an objective decision support tool for clinical prediction of short-term outcome in preterms who suffer episodes of low BP.

Effects of an extubation readiness test protocol at a tertiary care fully outborn neonatal intensive care unit

Background and objectives

Extubation readiness testing (ERT) in the Neonatal Intensive Care Unit (NICU) is highly variable and lacking standardized criteria. To address this gap, an evidence-based, inter-professionally developed ERT protocol was implemented to assess effectiveness on extubation failure within 72 h and on duration of intubation (DOI).

Methods

A longitudinal retrospective chart review in a level III, fully outborn NICU, of intubated infants admitted 1-year prior (Group 1), and 1 year after implementation (Group 2). Patients were extubated if they passed a 2-stage ERT protocol (3 min continuous positive airway pressure (CPAP) followed by 7 min CPAP + pressure support). Descriptive, comparative statistics, and univariate and multiple logistic regression were completed on all patients and a ≤32 6/7 weeks subgroup (intubated at day-of-life 1); p < 0.05 is considered significant.

Results

All patients (n = 589 (n = 294 Group 1, n = 295 Group 2)) were included (preterm, intubated day of life one subgroup: n = 42 Group 1, n = 38 Group 2). For all patients, extubation failure decreased significantly from 9.9% to 4.1% (p = 0.006); Group 1 patients were 2.42 times more likely to experience extubation failure compared with Group 2. Extubation failure in the preterm subgroup decreased from 21.7% to 2.6% (p = 0.01); Group 1 patients were 10.71 times more likely to experience extubation failure. Median DOI was similar in both groups for all patients and in the preterm subgroup.

Conclusions

A unique two-stage ERT protocol was effective at reducing extubation failure rate, without increasing DOI, largely in preterm infants. The evidence-based, interprofessionally developed ERT protocol and its integration into the NICU culture largely contributed to its success.

Prediction of short-term health outcomes in preterm neonates from heart-rate variability and blood pressure using boosted decision trees

BACKGROUND AND OBJECTIVE

Efficient management of low blood pressure (BP) in preterm neonates remains challenging with considerable variability in clinical practice. There is currently no clear consensus on what constitutes a limit for low BP that is a risk to the preterm brain. It is argued that a personalised approach rather than a population based threshold is more appropriate. This work aims to assist healthcare professionals in assessing preterm wellbeing during episodes of low BP in order to decide when and whether hypotension treatment should be initiated. In particular, the study investigates the relationship between heart rate variability (HRV) and BP in preterm infants and its relevance to a short-term health outcome.

METHODS

The study is performed on a large clinically collected dataset of 831 h from 23 preterm infants of less than 32 weeks gestational age. The statistical predictive power of common HRV features is first assessed with respect to the outcome. A decision support system, based on boosted decision trees (XGboost), was developed to continuously estimate the probability of neonatal morbidity based on the feature vector of HRV characteristics and the mean arterial blood pressure.

RESULTS

It is shown that the predictive power of the extracted features improves when observed during episodes of hypotension. A single best HRV feature achieves an AUC of 0.87. Combining multiple HRV features extracted during hypotensive episodes with the classifier achieves an AUC of 0.97, using a leave-one-patient-out performance assessment. Finally it is shown that good performance can even be achieved using continuous HRV recordings, rather than only focusing on hypotensive events - this had the benefit of not requiring invasive BP monitoring.

CONCLUSIONS

The work presents a promising step towards the use of multimodal data in providing objective decision support for the prediction of short-term outcome in preterm infants with hypotensive episodes.

The effects of nasal continuous positive airway pressure and high flow nasal cannula on heart rate variability in extremely preterm infants after extubation: A randomized crossover trial

BACKGROUND

NCPAP and High flow nasal cannula (HFNC) are common modes of non-invasive respiratory support used after extubation. Heart rate variability (HRV) has been demonstrated as a marker of well-being in neonates and differences in HRV were described in preterm infants receiving respiratory care. The objective was to investigate the effects of NCPAP and HFNC on HRV after extubation.

METHODS

Randomized crossover trial in infants with birth weight (BW) ≤1250 g after undergoing their first elective extubation. ECG recordings were performed during 45 min while on HFNC and nasal continuous positive airway pressure (NCPAP). Time domain, non-linear, and frequency domain parameters were calculated and compared during HFNC and NCPAP using paired nonparametric tests. A secondary analysis was performed in the subgroup of infants that were successfully extubated.

RESULTS

Thirty infants with median [range] gestational age of 27 weeks [24.1-29.3] and BW of 930 g [610-1220] were studied at 5 days [1-39] of age. No differences in HRV parameters were observed between HFNC and NCPAP. In the secondary analysis, infants successfully extubated (n = 27) had a significantly higher HRV during HFNC for some time domain parameters. For instance, the standard deviation of the RR intervals (SDRR) was more likely to be higher during HFNC compared to NCPAP (HFNC: 18/27 vs NCPAP: 9/27, P = 0.017) .

CONCLUSION

During the first hours after extubation, no differences in HRV were detected between HFNC and NCPAP in the overall cohort. However, a significantly higher HRV was noted during HFNC in the subgroup of infants successfully extubated.

Surfactant, steroids and non-invasive ventilation in the prevention of BPD

Bronchopulmonary dysplasia (BPD) is a complex disorder with multiple factors implicated in its etiopathogenesis. Despite the scientific advances in the field of neonatology, the incidence of BPD has remained somewhat constant due to increased survival of extremely premature infants. Surfactant deficiency in the immature lung, exposure to invasive mechanical ventilation leading to volutrauma, barotrauma and lung inflammation are some of the critical contributing factors to the pathogenesis of BPD. Hence, strategies to prevent BPD in the postnatal period revolve around mitigation of this injury and inflammation. This article reviews the progress made in the last 5 years in the development of new preparations of surfactant, use of corticosteroids and non-invasive ventilation in the prevention of BPD. Emerging techniques of surfactant delivery through minimally invasive and non-invasive routes are also discussed.

Autonomic nervous system depression at term in neurologically normal premature infants

BACKGROUND

Premature infants are vulnerable to destructive brain injury and disturbed neurological development. Prematurity may alter maturation of the central autonomic nervous system (ANS).

AIMS

To compare ANS function (using heart rate variability; HRV) between preterm infants with normal neuroimaging at term equivalent age and low-risk term controls. Study design, subjects. We performed a case-control study of preterm infants born ≤28 weeks gestational age that had normal brain imaging and archived continuous EKG data at term equivalent age. We documented other factors thought to influence ANS maturation (e.g. infection, ventilation days, and postnatal steroids). Controls were low-risk term gestational age newborns from uncomplicated pregnancies/deliveries. We characterized HRV metrics using frequency-(Welch periodogram) and time-domain (detrended fluctuation) analyses. Sympathetic tone was characterized by α1, root mean square analysis (RMS1 and RMS2), low-frequency (LF) power, and normalized LF (nLF) and parasympathetic tone was characterized by high-frequency (HF) power and normalized HF (nHF). α2 characterized ultraslow changes in heart rate. We used ANCOVA to compare HRV metrics between groups. Outcome measures, results. HRV from 26 preterm infants were compared to 55 controls. Analyzed HRV data for preterm infants were recorded at median (range) gestational age of 39 (36-39) weeks and for controls at 39 (37-41) weeks gestational age. α1, RMS2, LF and HF were significantly higher in control infants and remained significant after controlling for infection, ventilator days, and postnatal steroids (P < .005).

CONCLUSIONS

Autonomic maturation is impaired in a premature extrauterine environment. In the absence of destructive brain injury, our data suggest an important role for disturbed programming in this impaired autonomic development.

Predicting Extubation Outcomes-A Model Incorporating Heart Rate Characteristics Index

OBJECTIVE

To test the hypothesis that in neonates on mechanical ventilation, heart rate characteristics index (HRCi) can be combined with a clinical model for predicting extubation outcomes in neonates.

STUDY DESIGN

HRCi and clinical data for all intended intubation-extubation events (episodes) were retrospectively analyzed between June 2014 and January 2015. Each episode started 6 hours pre-extubation or at the time of primary intubation if ventilation duration was shorter than 6 hours (baseline). The episodes ended at 72 hours postextubation for successful extubations or at reintubation for failed extubations. Mean of 6 hourly epoch HRCi-scores (baseline) or fold-changes (postextubation) were analyzed. Results are expressed as medians (IQR) for continuous data and proportions for categorical data. Multivariable logistic regression mixed model was used for statistical analysis.

RESULTS

Sixty-six infants contributed to 96 episodes (18 failed extubations, 78 successful extubations) in the study. Failed extubations had significantly longer duration of ventilation (65.3 hours, 19.94-158.2 vs 38.4, 16.5-71.3) and more culture positive sepsis (33.3% vs 3.8%) than successful extubations. Baseline HRCi scores (1.68, 1.29-2.45 vs 0.95, 0.54-1.86) and postextubation epoch-1 fold changes (1.25, 0.94-1.55 vs 0.94, 0.82-1.11) were higher in failed extubations compared with successful extubations. Multivariable linear mixed-effects regression was used to create prediction models for success of extubation, using relevant variables.

CONCLUSIONS

The baseline and postextubation HRCi were significantly higher in neonates with extubation failure compared with those who succeeded. Models using HRCi and clinical variables to predict extubation success may add to the confidence of clinicians considering extubation.

Prediction of Extubation readiness in extremely preterm infants by the automated analysis of cardiorespiratory behavior: study protocol

Background

Extremely preterm infants (≤ 28 weeks gestation) commonly require endotracheal intubation and mechanical ventilation (MV) to maintain adequate oxygenation and gas exchange. Given that MV is independently associated with important adverse outcomes, efforts should be made to limit its duration. However, current methods for determining extubation readiness are inaccurate and a significant number of infants fail extubation and require reintubation, an intervention that may be associated with increased morbidities. A variety of objective measures have been proposed to better define the optimal time for extubation, but none have proven clinically useful. In a pilot study, investigators from this group have shown promising results from sophisticated, automated analyses of cardiorespiratory signals as a predictor of extubation readiness. The aim of this study is to develop an automated predictor of extubation readiness using a combination of clinical tools along with novel and automated measures of cardiorespiratory behavior, to assist clinicians in determining when extremely preterm infants are ready for extubation.

Methods

In this prospective, multicenter observational study, cardiorespiratory signals will be recorded from 250 eligible extremely preterm infants with birth weights ≤1250 g immediately prior to their first planned extubation. Automated signal analysis algorithms will compute a variety of metrics for each infant, and machine learning methods will then be used to find the optimal combination of these metrics together with clinical variables that provide the best overall prediction of extubation readiness. Using these results, investigators will develop an Automated system for Prediction of EXtubation (APEX) readiness that will integrate the software for data acquisition, signal analysis, and outcome prediction into a single application suitable for use by medical personnel in the neonatal intensive care unit. The performance of APEX will later be prospectively validated in 50 additional infants.

Discussion

The results of this research will provide the quantitative evidence needed to assist clinicians in determining when to extubate a preterm infant with the highest probability of success, and could produce significant improvements in extubation outcomes in this population.

Trial registration

Clinicaltrials.gov identifier: NCT01909947. Registered on July 17 2013.

Trial sponsor: Canadian Institutes of Health Research (CIHR).

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-017-0911-z) contains supplementary material, which is available to authorized users.

Dexamethasone effect on heart rate variability in preterm infants on mechanical ventilation

BACKGROUND

Dexamethasone is administered to some preterm infants with chronic lung disease to facilitate weaning from mechanical ventilation. Heart rate characteristics (HRC), including heart rate variability (HRV), may be impacted by glucocorticoids and may predict extubation readiness. A commercially available monitor developed for sepsis detection continuously calculates HRV and an HRC index, which are inversely related.

OBJECTIVES

Determine the impact of dexamethasone on HRV and the HRC index, in relation to extubation success.

METHODS

We identified 109 preterm infants who received dexamethasone while on mechanical ventilation and had HRC index monitoring data available. Average hourly HRV and HRC index were compared the day before and the day after initiation of dexamethasone in three groups: infants who remained on mechanical ventilation, those who were successfully extubated, and those who were extubated and required reintubation in < 3 days.

RESULTS

There was a significant increase in HRV and decrease in the HRC index the day after dexamethasone was started (HRV 16.2±0.5 vs 27.6±1.1 ms; HRC index 1.51±0.11 vs. 0.79±0.06 mean SE, p < 0.001). The 63 infants who were extubated within a day of starting dexamethasone had significantly higher HRV compared to those who remained on mechanical ventilation. There was no difference in HRV or its change with dexamethasone in the 45 infants who remained successfully extubated compared to the 18 infants who required reintubation within 3 days.

CONCLUSION

Dexamethasone improves HRV and lowers the HRC index in preterm infants with chronic lung disease on mechanical ventilation.

A pilot study: the role of the autonomic nervous system in cardiorespiratory regulation in infant feeding

AIM

The purpose of this pilot study was to examine the interplay between the parasympathetic (PNS) and sympathetic nervous systems' (SNS) contributions to prefeeding, feeding and satiation in young, healthy infants.

METHOD

This prospective study was completed on eleven full-term infants, less than 6 months old. Respiratory rate, heart rate, heart rate variability (HRV), electrodermal activity and low-frequency/high-frequency heart rate variability ratio were sampled from the infant during prefeeding, feeding and satiation periods.

RESULTS

A repeated-measures ANOVA revealed a significant difference in respiratory patterning during the three feeding phases (p = .049); however, none of the other physiological measures reached significance. An emerging trend across physiological measures suggests that the feeding phase was influenced by the SNS with increasing respiratory rate, heart rate, low-frequency HRV, electrodermal activity and decreasing high-frequency HRV compared to the prefeeding and satiation phases, which were influenced predominantly by the PNS.

CONCLUSION

Respiration rate increased significantly during the feeding phase compared to prefeeding and postfeeding phases. Emerging trends indicate a pattern of alternating relative tone in PNS versus SNS across feeding phases - with SNS predominating the feeding phase. More clinical research examining the SNS and PNS contributions to feeding should be completed across patient populations.

Correlation of clinical parameters with cardiorespiratory behavior in successfully extubated extremely preterm infants

Extremely preterm infants (gestational age ≤ 28 weeks) often require EndoTracheal Tube-Invasive Mechanical Ventilation (ETT-IMV) to survive. Clinicians wean infants off ETT-IMV as early as possible using their judgment and clinical information. However, assessment of extubation readiness is not accurate since 20 to 40% of preterm infants fail extubation. We extended our work in automated prediction of extubation readiness by examining correlations of automated cardiorespiratory features to clinical parameters in successfully extubated infants. Only a few features, mainly those related to variability of breathing synchrony, had any consistent correlation with clinical parameters, namely gestational age, day of life at extubation, and bicarbonate. We conclude that the automated cardiorespiratory features likely provide different information additional to clinical practice.