Perfusion index in healthy newborns during critical congenital heart disease screening at 24 hours: retrospective observational study from the USA

Distribution and reference values of peripheral perfusion index in neonates from population-wide screening

BACKGROUND

Peripheral perfusion index (PPI) is useful in a variety of neonatal settings. Currently, available reference values are from small numbers and highly variable.

METHODS

We sought to generate reference values of PPI by analysing previously collected data from newborns who underwent mandated universal pulse oximetry and PPI screening from 2018 to 2021 using uniform protocol and equipment. Q-Q plots and boxplots were used to visualise distributions. Kernel density estimation for heaped and rounded data was used to estimate percentiles of the distributions.

RESULTS

Data from 388 205 newborns who underwent universal pulse oximetry screening in the first week of life were used for this analysis. Pre and postductal values showed a non-normal distribution and skewed to the left, the former had a thicker tail with more extreme values. Minor, but statistically significant differences were seen in the PPI values from day 1 to 7. Median preductal PPI (2.77, IQR:1.83-3.93) was significantly higher than postductal (2.38 IQR: 1.41-3.55) (p<0.01). PPI values increased with weight and boys had higher PPI. Kernel estimates of the percentiles in the overall sample and subgroups for gender and weight have been provided for preductal and post-ductal values.

CONCLUSION

This study, based on the largest available dataset, provides reference values for PPI in newborns. A significant influence of gender and birth weight on PPI values in newborns has been identified. Future research on understanding the influence of age, sex, birth weight, gestational age, ambient temperature and genetic factors on PPI is recommended.

Machine Learning-Based Critical Congenital Heart Disease Screening Using Dual-Site Pulse Oximetry Measurements

BACKGROUND

Oxygen saturation (Spo2) screening has not led to earlier detection of critical congenital heart disease (CCHD). Adding pulse oximetry features (ie, perfusion data and radiofemoral pulse delay) may improve CCHD detection, especially coarctation of the aorta (CoA). We developed and tested a machine learning (ML) pulse oximetry algorithm to enhance CCHD detection.

METHODS AND RESULTS

Six sites prospectively enrolled newborns with and without CCHD and recorded simultaneous pre- and postductal pulse oximetry. We focused on models at 1 versus 2 time points and with/without pulse delay for our ML algorithms. The sensitivity, specificity, and area under the receiver operating characteristic curve were compared between the Spo2-alone and ML algorithms. A total of 523 newborns were enrolled (no CHD, 317; CHD, 74; CCHD, 132, of whom 21 had isolated CoA). When applying the Spo2-alone algorithm to all patients, 26.2% of CCHD would be missed. We narrowed the sample to patients with both 2 time point measurements and pulse-delay data (no CHD, 65; CCHD, 14) to compare ML performance. Among these patients, sensitivity for CCHD detection increased with both the addition of pulse delay and a second time point. All ML models had 100% specificity. With a 2-time-points+pulse-delay model, CCHD sensitivity increased to 92.86% (P=0.25) compared with Spo2 alone (71.43%), and CoA increased to 66.67% (P=0.5) from 0. The area under the receiver operating characteristic curve for CCHD and CoA detection significantly improved (0.96 versus 0.83 for CCHD, 0.83 versus 0.48 for CoA; both P=0.03) using the 2-time-points+pulse-delay model compared with Spo2 alone.

CONCLUSIONS

ML pulse oximetry that combines oxygenation, perfusion data, and pulse delay at 2 time points may improve detection of CCHD and CoA within 48 hours after birth.

REGISTRATION

URL: https://www.clinicaltrials.gov/study/NCT04056104?term=NCT04056104&rank=1; Unique identifier: NCT04056104.

Use of Pulse Oximetry Pulsatility Index Screening for Critical Congenital Heart Disease

OBJECTIVE

This study aimed to compare oximetry data (pre- and postductal oxygen saturation [SpO2], pre- and postductal pulsatility index [PI]) in healthy newborns (≥35 weeks' gestational age) to infants who have critical congenital heart disease (CCHD).

STUDY DESIGN

This is a retrospective analysis of data obtained from electronic medical records, recorded as part of routine pulse oximetry screening (POS) for CCHD in infants born between the years 2013 and 2020. Testing was performed at 24 ± 2 hours of life. Data were analyzed to detect differences in pre- and postductal SpO2 and pre- and postductal PI in healthy newborns compared with infants who have CCHD. Newborns were excluded from analysis if they: (1) had a prenatal diagnosis of CCHD in the medical record, (2) had previously been admitted to the neonatal intensive care unit, or (3) had failed POS but were found no CCHD by diagnostic echocardiography.

RESULTS

A total of 88,754 healthy newborns had received POS between the years 2013 and 2020. Of the 88,736 newborn records available for analysis,18 newborns were diagnosed with CCHD. Eight were identified by POS before discharge and 10 were diagnosed after discharge. Infants diagnosed with CCHD by POS had lower pre- and postductal SpO2 compared with normal infants. Their postductal PI was significantly lower. Infants who had CCHD that was not identified by POS had similar pre- and postductal SpO2 values, but their postductal PI was lower. Using a postductal PI cutoff of 1.21 had a receiver operating curve of area under the curve 0.77 (95% confidence interval: 0.672, 0.869) with 74% sensitivity and 61% specificity.

CONCLUSION

In our large cohort of infants born in San Diego County, the postductal PI is lower in infants with CCHD. Given that PI is routinely displayed on every pulse oximeter and the high morbidity of missed CCHD, PI should be incorporated into routine CCHD screening.

KEY POINTS

· Postductal PI is lower in newborn who presented later with congenital heart disease.. · Postductal PI cut-off of 1.21 may help practitioners determine if a newborn is at risk for CCHD.. · This large cohort study demonstrates that a low PI can detect additional CCHD cases..

Evaluation of tissue perfusion status in moderate to late preterm

The aim of this study was to investigate the tissue perfusion status and circadian rhythm in moderately premature infants. As a prospective study, from July 2019 to October 2019, the haemodynamic stability of moderate to late preterm, including such indicators as perfusion index (PI), blood pressure (systolic/diastolic) (BP), heart rate (HR), respiratory rate (RR), oxygen saturation (SpO2) and body temperature were monitored in the morning and at night within eight days after birth. There was no difference of statistical significance between PI values in the morning and at night (P>0.05). The HR from days six to eight after birth was higher than days one to three (P<0.05). The HR increased significantly on days seven and eight compared with days four and five (P<0.05). The BP from days three to eight was significantly higher than on day one (P<0.05), and the BP from days four to eight was higher than on day two. There was a weak positive correlation between the PI values and gestational age (GA) (r=0.097), HR (r=0.067) and time (r=0.284), and a negative correlation with SpO2 (r=-0.113). The PI and HR of moderate to late preterm increased within eight days after birth. BP was relatively lower after birth and gradually increased to a stable level on days three to four. The PI and BP circadian rhythms associated with tissue perfusion were not established on day eight after birth.

Peripheral Saturation and Perfusion Index on the First Day of Life Play a Role in Early Discharge of Healthy Term Newborns

INTRODUCTION

Pulse oximetry screening is a safe, feasible test, effective in identifying congenital heart diseases in otherwise well-appearing newborns. Uncertainties still persist on the most effective algorithm to be used and the timing of screening. The aim of this study was to evaluate the role of the pulse oximetry screening associated with the peripheral perfusion index performed in the first 24 hours of life for the early detection of congenital heart diseases and noncongenital heart diseases in the newborns.

MATERIALS AND METHODS

A prospective observational cohort study was conducted. The enrollment criteria were as follows: term newborns with an APGAR score >8 at 5 minutes. The exclusion criteria were as follows: clinical signs of prenatal/perinatal asphyxia or known congenital malformations. Four parameters of pulse oximetry screening were utilized: saturation less than 90% (screening 1), saturation of less than 95% in one or both limbs (screening 2), difference of more than 3% between the limbs (screening 3), and preductal peripheral perfusion index or postductal peripheral perfusion index below 0.70 (screening 4). The likelihood ratio, sensibility, specificity, and positive and negative predictive values for identification of congenital heart diseases or noncongenital heart diseases (suspicion of perinatal infection and any respiratory diseases) were evaluated.

RESULTS

The best predictive results for minor congenital heart disease were obtained combining screening 3 and screening 4 (χ ² (1) = 15,279; p < 0.05; OR = 57,900 (9,465-354,180)). Screening 2, screening 3, and screening 4 were predictive for noncongenital heart diseases (χ ² (1) = 11,550; p < 0.05; OR = 65,744 (10,413-415,097)). Combined screenings 2-4 were predictive for both congenital heart disease and noncongenital heart disease (χ ² (1) = 22,155; p < 0.05; OR = 117,685 (12,972-1067,648)).

CONCLUSIONS

Combining peripheral saturation with the peripheral perfusion index in the first 24 hours of life shows a predictive role in the detection of minor congenital heart diseases and neonatal clinical conditions whose care needs attention.

Low false-positive rate of perfusion index as a screening tool for neonatal aortic coarctation

Aim

Adding perfusion index (PI) to pulse oximetry screening (POS) may increase neonatal detection of CoA (aortic coarctation). A cut‐off <0.7% has been suggested but is associated with a high rate of false positives. We aimed to evaluate the specificity of PI when using repeated instead of single measurements.

Methods

A pilot study was conducted in 50 neonates. PI was recorded in right hand and a foot by pulse oximeter. If PI was <0.7%, the measurement was immediately repeated up to 3 times. If all three measurements were <0.7% in hand and/or foot the screen was positive and echocardiography was performed. There were 3/50 false‐positive screens. The protocol was therefore modified requiring 30 min intervals between measurements.

Results

An additional 463 neonates were included using the modified protocol at a median age of 18 h. There were no false positives. The only neonate with CoA had a negative screen (PI hand 1.2% and foot 0.8%). The measurement required on average an extra 3 min and 30 s compared with POS only.

Conclusion

The false‐positive rate of PI was reduced by using repeated PI measurements. The sensitivity for CoA using this protocol should be evaluated in large‐scale prospective studies.

Oxygen saturation and perfusion index screening in neonates at high altitudes: can PDA be predicted?

Screening critical congenital heart disease in neonates with 24-48 h of age could be made by oxygen saturation determination. Perfusion index may be used as an adjunct to pulse oximetry screening to detect non-cyanotic critical congenital heart disease cases such as a left heart outflow obstruction. We evaluate the results of combined screening for oxygen saturation and peripheral perfusion index at high altitudes. The study included 501 neonates older than gestational week 35. The mean oxygen saturation was lower than at sea level, and the screening test was positive in a total of 21 (4.2%) babies. Critical congenital heart diseases were not detected in any patient. A total of 10 (2%) babies were detected with PDA, nine (1.8%) of whom recorded a positive screening test. The prevalence of PDA was significantly higher in the positive screening test group when compared with those who underwent echocardiography due to clinical findings.Conclusion: The median peripheral perfusion index at high altitude was not lower than at sea level, while the mean oxygen saturation, in contrast, was lower than at sea level. The low partial oxygen pressure found at high altitudes leads to a variation in postnatal adaptation and an increased prevalence of PDA. Accordingly, oxygen saturation screening may serve to identify babies with PDA at high altitudes. What is Known: • Oxygen saturation is known to be low at high altitudes, and thus the rates of false positivity are high when screening for critical congenital heart disease. • High altitudes are also associated with an increased prevalence of simple congenital heart disease. What is New: • The peripheral perfusion index at high altitude is not lower than at sea level. • The prevalence of PDA is significantly higher in those with false positive screening results.

A novel system to collect dual pulse oximetry data for critical congenital heart disease screening research

Introduction

Access to patient medical data is critical to building a real-time data analytic pipeline for improving care providers' ability to detect, diagnose, and prognosticate diseases. Critical congenital heart disease (CCHD) is a common group of neonatal life-threatening defects that must be promptly diagnosed to minimize morbidity and mortality. CCHD can be diagnosed both prenatally and postnatally. However, despite current screening practices involving oxygen saturation analysis, timely diagnosis is missed in approximately 900 infants with CCHD annually in the USA and can benefit from increased data processing capabilities. Adding non-invasive perfusion measurements to oxygen saturation data can improve the timeliness and fidelity of CCHD diagnostics. However, real-time monitoring and interpretation of non-invasive perfusion data are currently limited.

Methods

To address this challenge, we created a hardware and software architecture utilizing a Pi-top™ for collecting, visualizing, and storing dual oxygen saturation, perfusion indices, and photoplethysmography data. Data aggregation in our system is automated and all data files are coded with unique study identifiers to facilitate research purposes.

Results

Using this system, we have collected data from 190 neonates, 130 presumably without and 60 with congenital heart disease, in total comprising 1665 min of information. From these data, we are able to extract non-invasive perfusion features such as perfusion index, radiofemoral delay, and slope of systolic rise or diastolic fall.

Conclusion

This data collection and waveform analysis is relatively inexpensive and can be used to enhance future CCHD screening algorithms.