Predicting Extubation Readiness in Preterm Infants Utilizing Machine Learning: A Diagnostic Utility Study.

OBJECTIVE: The objective of this study was to predict extubation readiness in preterm infants using machine learning analysis of bedside pulse oximeter and ventilator data. STUDY DESIGN: This is an observational study with prospective recordings of oxygen saturation (SpO2) and ventilator data from infants <30 weeks of gestation age. Research pulse oximeters collected SpO2 (1 Hz sampling rate) to quantify intermittent hypoxemia (IH). Continuous ventilator metrics were collected (4-5-minute sampling) from bedside ventilators. Data modeling was completed using unbiased machine learning algorithms. Three model sets were created using the following data source combinations: (1) IH and ventilator (IH + SIMV), (2) IH, and (3) ventilator (SIMV). Infants were also analyzed separated by postnatal age (infants <2 or ≥2 weeks of age). Models were compared by area under the receiver operating characteristic curve (AUC). RESULTS: A total of 110 extubation events from 110 preterm infants were analyzed. Infants had a median gestation age and birth weight of 26 weeks and 825 g, respectively. Of the 3 models presented, the IH + SIMV model achieved the highest AUC of 0.77 for all infants. Separating infants by postnatal age increased accuracy further achieving AUC of 0.94 for <2 weeks of age group and AUC of 0.83 for ≥2 weeks group. CONCLUSIONS: Machine learning analysis has the potential to enhance prediction accuracy of extubation readiness in preterm infants while utilizing readily available data streams from bedside pulse oximeters and ventilators.

The impact of intermittent hypoxemia on type 1 retinopathy of prematurity in preterm infants.

BACKGROUND: Intermittent hypoxemia (IH) may influence retinopathy of prematurity (ROP) development in preterm infants, however, previous studies had mixed results. This study tests the hypothesis that increased IH is associated with Type 1 ROP; a stage beyond which treatment is indicated. METHODS: IH was quantified by continuously monitoring oxygen saturation (SpO2) using high-resolution pulse oximeters during the first 10 weeks of life. Statistical analyses assessed the relationship and predictive ability of weekly and cumulative IH for Type 1 ROP development. RESULTS: Most analyses showed no association between IH and Type 1 ROP adjusting for gestational age (GA) and birth weight (BW). However, cumulative IH of longer duration during weeks 5-10, 6-10, and 7-10 were significantly associated with Type 1 ROP adjusting for GA and BW, e.g., the adjusted odds ratio of Type 1 ROP was 2.01 (p = 0.03) for every 3.8 seconds increase in IH duration from week 6-10. IH did not provide statistically significant added predictive ability above GA and BW. CONCLUSIONS: For most analyses there was no significant association between IH and Type 1 ROP adjusting for GA and BW. However, infants with longer IH duration during the second month of life had higher risk for Type 1 ROP. IMPACT: The relationship and predictive ability of intermittent hypoxemia (IH) on retinopathy of prematurity (ROP) is controversial. This study shows no significant association between IH events and Type 1 ROP after adjusting for gestational age (GA) and birth weight (BW), except for cumulative IH of longer duration in the second month of life. In this cohort, IH does not provide a statistically significant improvement in ROP prediction over GA and BW. This study is the first to assess the cumulative impact of IH measures on Type 1 ROP. Interventions for reducing IH duration during critical postnatal periods may improve ROP outcomes.

Wearable fiber-free optical sensor for continuous monitoring of neonatal cerebral blood flow and oxygenation.

BACKGROUND: Unstable cerebral hemodynamics places preterm infants at high risk of brain injury. We adapted an innovative, fiber-free, wearable diffuse speckle contrast flow-oximetry (DSCFO) device for continuous monitoring of both cerebral blood flow (CBF) and oxygenation in neonatal piglets and preterm infants. METHODS: DSCFO uses two small laser diodes as focused-point and a tiny CMOS camera as a high-density two-dimensional detector to detect spontaneous spatial fluctuation of diffuse laser speckles for CBF measurement, and light intensity attenuations for cerebral oxygenation measurement. The DSCFO was first validated against the established diffuse correlation spectroscopy (DCS) in neonatal piglets and then utilized for continuous CBF and oxygenation monitoring in preterm infants during intermittent hypoxemia (IH) events. RESULTS: Significant correlations between the DSCFO and DCS measurements of CBF variations in neonatal piglets were observed. IH events induced fluctuations in CBF, cerebral oxygenation, and peripheral cardiorespiratory vitals in preterm infants. However, no consistent correlation patterns were observed among peripheral and cerebral monitoring parameters. CONCLUSIONS: This pilot study demonstrated the feasibility of DSCFO technology to serve as a low-cost wearable sensor for continuous monitoring of multiple cerebral hemodynamic parameters. The results suggested the importance of multi-parameter measurements for understanding deep insights of peripheral and cerebral regulations. IMPACT: The innovative DSCFO technology may serve as a low-cost wearable sensor for continuous bedside monitoring of multiple cerebral hemodynamic parameters in neonatal intensive care units. Concurrent DSCFO and DCS measurements of CBF variations in neonatal piglet models generated consistent results. No consistent correlation patterns were observed among peripheral and cerebral monitoring parameters in preterm neonates, suggesting the importance of multi-parameter measurements for understanding deep insights of peripheral and cerebral regulations during IH events. Integrating and correlating multiple cerebral functional parameters with clinical outcomes may identify biomarkers for prediction and management of IH associated brain injury.

A Wearable Fiber-Free Optical Sensor for Continuous Monitoring of Neonatal Cerebral Blood Flow and Oxygenation.

Impact: The innovative DSCFO technology may serve as a low-cost wearable sensor for continuous bedside monitoring of multiple cerebral hemodynamic parameters in neonatal intensive care units.Concurrent DSCFO and DCS measurements of CBF variations in neonatal piglet models generated consistent results.No consistent correlation patterns were observed among peripheral and cerebral monitoring parameters in preterm neonates, suggesting the importance of multi-parameter measurements for understanding deep insights of peripheral and cerebral regulations during IH events.Integrating and correlating multiple cerebral functional parameters with clinical outcomes may identify biomarkers for prediction and management of IH associated brain injury. Background: Unstable cerebral hemodynamics places preterm infants at high risk of brain injury. We adapted an innovative, fiber-free, wearable diffuse speckle contrast flow-oximetry (DSCFO) device for continuous monitoring of both cerebral blood flow (CBF) and oxygenation in neonatal piglets and preterm infants. Methods: DSCFO uses two small laser diodes as focused-point and a tiny CMOS camera as a high-density two-dimensional detector to detect spontaneous spatial fluctuation of diffuse laser speckles for CBF measurement, and light intensity attenuations for cerebral oxygenation measurement. The DSCFO was first validated against the established diffuse correlation spectroscopy (DCS) in neonatal piglets and then utilized for continuous CBF and oxygenation monitoring in preterm infants during intermittent hypoxemia (IH) events. Results: Consistent results between the DSCFO and DCS measurements of CBF variations in neonatal piglets were observed. IH events induced fluctuations in CBF, cerebral oxygenation, and peripheral cardiorespiratory vitals in preterm infants. However, no consistent correlation patterns were observed among peripheral and cerebral monitoring parameters. Conclusions: This pilot study demonstrated the feasibility of DSCFO technology to serve as a low-cost wearable sensor for continuous monitoring of multiple cerebral hemodynamic parameters. The results suggested the importance of multi-parameter measurements for understanding deep insights of peripheral and cerebral regulations.

The Impact of Intermittent Hypoxemia on Type 1 Retinopathy of Prematurity in Preterm Infants.

Background: Intermittent hypoxemia (IH) may influence retinopathy of prematurity (ROP) development in preterm infants, however, previous studies had mixed results. This study aims to assess the influence and evaluate the predictive ability of IH measures on Type 1 ROP, a stage beyond which ROP treatment is indicated. Methods: IH was quantified by continuously monitoring oxygen saturation (SpO2) using high-resolution pulse oximeters during the first 10 weeks of life. Statistical analyses assessed the relationship and predictive ability of weekly and cumulative IH variables for Type 1 ROP development. Results: Univariate analyses suggested that IH measures are greater in infants with Type 1 ROP and are predictive of Type 1 ROP development. Multivariable logistic regression analyses revealed that cumulative IH of longer duration during certain postnatal periods are associated with Type 1 ROP development after adjusting for gestational age (GA) or birth weight (BW). Although area under the curve (AUC) analyses revealed added predictivity of cumulative IH variables above GA or BW, these increments in AUC were not statistically significant. Conclusions: The duration of IH events was associated with Type 1 ROP development. Interventions for reducing the duration of IH events may potentially improve ROP outcomes.

Adverse effects of COVID-19 pandemic on a multicenter randomized controlled trial.

OBJECTIVE: Describe the effects of the COVID-19 pandemic on subject enrollment in a multicenter randomized controlled trial. STUDY DESIGN: We assessed the number of eligible infants approached and consented for enrollment over five separate epochs including baseline, peak pandemic, and gradual but incomplete recovery. RESULT: The pandemic had a major effect on ability to approach parents for consent. Parents approached dropped from 95.4% baseline to 13.1% in the peak pandemic epoch and has not recovered to baseline even in the just-completed post-pandemic epoch (84.9%). Despite the decrease in subjects approached, there was no significant change in the overall consent rate for the study CONCLUSION: The pandemic has significantly limited ability to approach parents of eligible infants for consent, with only partial recovery. Opportunities for interactions of investigators and study coordinators with parents continue to present challenges limiting full recovery.

Aerosolized Surfactant for Preterm Infants with Respiratory Distress Syndrome.

Currently, the administration of surfactant to preterm infants with respiratory distress syndrome (RDS) mainly relies on intratracheal instillation; however, there is increasing evidence of aerosolized surfactant being an effective non-invasive strategy. We present a historical narrative spanning sixty years of development of aerosolization systems. We also offer an overview of the pertinent mechanisms needed to create and manage the ideal aerosolization system, with a focus on delivery, distribution, deposition, and dispersion in the context of the human lung. More studies are needed to optimize treatment with aerosolized surfactants, including determination of ideal dosages, nebulizer types, non-invasive interfaces, and breath synchronization. However, the field is rapidly evolving, and widespread clinical use may be achieved in the near future.

Response to first dose of inhaled albuterol in mechanically ventilated preterm infants.

BACKGROUND: Bronchodilator responses among preterm infants are heterogeneous. Bedside measurements may identify responders. STUDY DESIGN: Respiratory measurements (Resistance, Compliance, FiO2) and pulse oximetry (SpO2) patterns were downloaded from infants <30 weeks gestational age during the first 2 months of life. Mechanically ventilated infants who received albuterol were included (n = 33). Measurements were compared before and after first albuterol. Secondary analyses assessed subsequent doses. RESULTS: Median gestation and birthweight were 25 3/7 weeks and 730 g, respectively. Mean Resistance decreased post-albuterol (p = 0.007). Sixty-eight percent of infants were responders based on decreased Resistance. Compliance and FiO2 did not significantly differ. Percent time in hypoxemia (SpO2 < 85%) decreased post albuterol (p < 0.02). In responders, Resistance changes diminished with subsequent administration (all p = 0.01). CONCLUSIONS: Ventilator resistance decreased in two-thirds of preterm infants, consistent with studies that utilized formal pulmonary function testing. Albuterol had a variable effect on delivered FiO2; however, hypoxemia may be useful in evaluating albuterol response.

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.

Prematurity and postnatal alterations in intermittent hypoxaemia.

Intermittent hypoxaemia (IH) events are well described in extremely preterm infants, but the occurrence of IH patterns in more mature preterm infants remains unclear. The objective of this study was to characterise the effect of gestational age on early postnatal patterns of IH in extremely (<28 weeks), very (28-<32 weeks) and moderately (32-<34 weeks) preterm infants. As expected, extremely preterm infants had a significantly higher frequency of IH events of longer durations and greater time with hypoxaemia versus very and moderately preterm infants. In addition, the postnatal decrease in IH duration was comparable in the very and moderately preterm infants. This progression of IH events should assist clinicians and families in managing expectations for resolution of IH events during early postnatal life.

Simultaneous measurements of tissue blood flow and oxygenation using a wearable fiber-free optical sensor.

SIGNIFICANCE: There is an essential need to develop wearable multimodality technologies that can continuously measure both blood flow and oxygenation in deep tissues to investigate and manage various vascular/cellular diseases. AIM: To develop a wearable dual-wavelength diffuse speckle contrast flow oximetry (DSCFO) for simultaneous measurements of blood flow and oxygenation variations in deep tissues. APPROACH: A wearable fiber-free DSCFO probe was fabricated using 3D printing to confine two small near-infrared laser diodes and a tiny CMOS camera in positions for DSCFO measurements. The spatial diffuse speckle contrast and light intensity measurements at the two different wavelengths enable quantification of tissue blood flow and oxygenation, respectively. The DSCFO was first calibrated using tissue phantoms and then tested in adult forearms during artery cuff occlusion. RESULTS: Phantom tests determined the largest effective source-detector distance (15 mm) and optimal camera exposure time (10 ms) and verified the accuracy of DSCFO in measuring absorption coefficient variations. The DSCFO detected substantial changes in forearm blood flow and oxygenation resulting from the artery occlusion, which meet physiological expectations and are consistent with previous study results. CONCLUSIONS: The wearable DSCFO may be used for continuous and simultaneous monitoring of blood flow and oxygenation variations in freely behaving subjects.

Intermittent Hypoxemia in Preterm Infants: A Potential Proinflammatory Process.

OBJECTIVE: A major consequence of prematurity is intermittent hypoxemia (IH). Data from both adult studies and neonatal animal models suggest that IH is proinflammatory; however, there is limited data in preterm infants. Here, we assess the relationship between IH and systemic inflammation, namely, serum C-reactive protein (CRP) in preterm infants. STUDY DESIGN: Serum CRP was measured at 30 days of life, at the time of peak IH frequency. IH measures (e.g., per cent time in hypoxemia, frequency, duration) were calculated the week prior to CRP collection. Statistical analyses were based on Spearman's correlation. RESULTS: A total of 26 infants were included. Median gestational age and birth weight were 274/7 weeks and 980 g, respectively. There were positive correlations between primary IH measures and CRP levels, especially for events longer than 1-minute duration (r range: 0.56-0.74, all p < 0.01). CONCLUSION: We demonstrate that IH is associated with increased CRP for the first time in preterm infants. Our findings are consistent with studies from adults and neonatal animal models suggesting that IH is a proinflammatory process. KEY POINTS: · IH events are common.. · IH is associated with elevated C-reactive protein.. · Longer IH events (>1 min) are of most significance..

Hypothyroidism after Percutaneous Patent Ductus Arteriosus Device Closure in an Extremely Preterm Infant: Possible Role of Iodinated IV Contrast.

We report a case of contrast-induced hypothyroidism in an extremely preterm infant after percutaneous patent ductus arteriosus (PDA) device closure. Iodine-induced hypothyroidism after exposure to iodine-containing antiseptics and contrast media has been previously reported in extremely preterm infants. However, this is the first report of contrast-induced hypothyroidism in an extremely preterm infant undergoing percutaneous PDA device closure. This is timely, given percutaneous PDA device closure is more frequently utilized. Guidelines for screening thyroid function pre and post contrast-requiring procedures may be warranted. Hypothyroidism if left untreated can have detrimental effects on developing brain, especially in the preterm population. Therefore, the earlier detection and treatment of iodine-induced hypothyroidism is imperative.

Aerosolized Calfactant for Newborns With Respiratory Distress: A Randomized Trial.

BACKGROUND: Exogenous surfactants to treat respiratory distress syndrome (RDS) are approved for tracheal instillation only; this requires intubation, often followed by positive pressure ventilation to promote distribution. Aerosol delivery offers a safer alternative, but clinical studies have had mixed results. We hypothesized that efficient aerosolization of a surfactant with low viscosity, early in the course of RDS, could reduce the need for intubation and instillation of liquid surfactant. METHODS: A prospective, multicenter, randomized, unblinded comparison trial of aerosolized calfactant (Infasurf) in newborns with signs of RDS that required noninvasive respiratory support. Calfactant was aerosolized by using a Solarys nebulizer modified with a pacifier adapter; 6 mL/kg (210 mg phospholipid/kg body weight) were delivered directly into the mouth. Infants in the aerosol group received up to 3 treatments, at least 4 hours apart. Infants in the control group received usual care, determined by providers. Infants were intubated and given instilled surfactant for persistent or worsening respiratory distress, at their providers' discretion. RESULTS: Among 22 NICUs, 457 infants were enrolled; gestation 23 to 41 (median 33) weeks and birth weight 595 to 4802 (median 1960) grams. In total, 230 infants were randomly assigned to aerosol; 225 received 334 treatments, starting at a median of 5 hours. The rates of intubation for surfactant instillation were 26% in the aerosol group and 50% in the usual care group (P < .0001). Respiratory outcomes up to 28 days of age were no different. CONCLUSIONS: In newborns with early, mild to moderate respiratory distress, aerosolized calfactant at a dose of 210 mg phospholipid/kg body weight reduced intubation and surfactant instillation by nearly one-half.

Noncontact optical imaging of brain hemodynamics in preterm infants: a preliminary study.

Extremely preterm infants' hemodynamic instability places them at high risk of brain injury. Currently there is no reliable bedside method to continuously monitor cerebral hemodynamics in the neonatal intensive care unit (NICU). This paper reports a feasibility study to adapt and test an innovative speckle contrast diffuse correlation tomography (scDCT) device for noncontact, high-density, 3D imaging of cerebral blood flow (CBF) in preterm infants. The scDCT scans a focused point near-infrared illumination to multiple source positions for deep tissue penetration, and controls an electron multiplying charge-coupled-device camera with thousands of pixels to achieve a high-density sampling. The optimized scDCT for use in preterm infants was first evaluated against an established diffuse correlation spectroscopy in an infant-head-simulating phantom with known properties. The observed significant correlation between the two measurements verified the capability of scDCT for transcranial brain imaging. The insignificant influence of transparent incubator wall on scDCT measurements was then confirmed by comparing adult forearm blood flow responses to artery cuff occlusions measured inside and outside the incubator. Finally, the scDCT device was moved to the NICU to image CBF variations in two preterm infants. Infant #1 with no major organ deficits showed little CBF fluctuation over the first 3 weeks of life. Infant #2 showed a significant CBF increase after the 2 h pharmacotherapy for patent ductus arteriosus closure. While these CBF variations meet physiological expectations, the fact that no significant changes are noted with peripheral monitoring of blood oxygen saturation suggests necessity of direct cerebral monitoring. This feasibility study with timely technology development is an important and necessary step towards larger clinical studies with more subjects to further validate it for continuous monitoring and instant management of cerebral pathologies and interventions in the NICU.

Transmitted Home Oximetry and Duration of Home Oxygen in Premature Infants.

OBJECTIVES: To determine if a home oxygen therapy (HOT) management strategy that includes analysis of recorded home oximetry (RHO) data, compared with standard monthly clinic visit assessments, reduces duration of HOT without harm in premature infants. METHODS: The RHO trial was an unmasked randomized clinical trial conducted in 9 US medical centers from November 2013 to December 2017, with follow-up to February 2019. Preterm infants with birth gestation ≤37 + 0/7 weeks, discharged on HOT, and attending their first pulmonary visit were enrolled. The intervention was an analysis of transmitted RHO between clinic visits (n = 97); the standard-care group received monthly clinic visits with in-clinic weaning attempts (n = 99). The primary outcomes were the duration of HOT and parent-reported quality of life. There were 2 prespecified secondary safety outcomes: change in weight and adverse events within 6 months of HOT discontinuation. RESULTS: Among 196 randomly assigned infants (mean birth gestational age: 26.9 weeks; SD: 2.6 weeks; 37.8% female), 166 (84.7%) completed the trial. In the RHO group, the mean time to discontinue HOT was 78.1 days (SE: 6.4), compared with 100.1 days (SE: 8.0) in the standard-care group (P = .03). The quality-of-life scores improved from baseline to 3 months after discontinuation of HOT in both groups (P = .002), but the degree of improvement did not differ significantly between groups (P = .75). CONCLUSIONS: RHO was effective in reducing the duration of HOT in premature infants. Parent quality of life improved after discontinuation. RHO allows physicians to determine which infants can be weaned and which need prolonged oxygen therapy between monthly visits.

A Wearable Fiberless Optical Sensor for Continuous Monitoring of Cerebral Blood Flow in Mice.

Continuous and longitudinal monitoring of cerebral blood flow (CBF) in animal models provides information for studying the mechanisms and interventions of various cerebral diseases. Since anesthesia may affect brain hemodynamics, researchers have been seeking wearable devices for use in conscious animals. We present a wearable diffuse speckle contrast flowmeter (DSCF) probe for monitoring CBF variations in mice. The DSCF probe consists of a small low-power near-infrared laser diode as a point source and an ultra-small low-power CMOS camera as a 2D detector array, which can be affixed on a mouse head. The movement of red blood cells in brain cortex (i.e., CBF) produces spatial fluctuations of laser speckles, which are captured by the camera. The DSCF system was calibrated using tissue phantoms and validated in a human forearm and mouse brains for continuous monitoring of blood flow increases and decreases against the established technologies. Significant correlations were observed among these measurements (R2 ≥ 0.80, p < 10-5). This small fiberless probe has the potential to be worn by a freely moving conscious mouse. Moreover, the flexible source-detector configuration allows for varied probing depths up to ~8 mm, which is sufficient for transcranially detecting CBF in the cortices of rodents and newborn infants.

Noninvasive noncontact speckle contrast diffuse correlation tomography of cerebral blood flow in rats.

Continuous and longitudinal imaging of cerebral blood flow (CBF) variations provide vital information to investigate pathophysiology and interventions for a variety of neurological and cerebral diseases. An innovative noncontact speckle contrast diffuse correlation tomography (scDCT) system was downscaled and adapted for noninvasive imaging of CBF distributions in rat brain through intact scalp and skull. Algorithms for 2D mapping and 3D image reconstruction of CBF distributions were developed and optimized. The continuous imaging capability of the system was shown by imaging global CBF increases during CO2 inhalations and regional CBF decreases across two hemispheres during sequential unilateral and bilateral common carotid artery ligations. The longitudinal imaging capability was demonstrated by imaging CBF variations over a long recovery period of 14 days after an acute stroke. Compared to the 2D mapping method, the 3D imaging method reduces partial volume effects, but needs more computation time for image reconstruction. Results from this study generally agree with those reported in the literature using similar protocols to induce CBF changes in rats. The scDCT enables a relatively large penetration depth (up to ∼10 mm), which is sufficient for transcranial brain measurements in small animals and human neonates. Ultimately, we expect to provide a noninvasive noncontact cerebral imager for basic neuroscience research in small animal models and clinical applications in human neonates.