Perfusion index as a screening test for neonatal aortic coarctation: Should we be using it routinely?

Pulse Oximetry Screening for Critical Congenital Heart Defects in Newborn Babies

Pulse oximetry screening (POS) was first described over 20 years ago. However, in recent years, major clinical trials have demonstrated consistent test accuracy for the detection of critical congenital heart defects (CCHD). International uptake of POS has progressed well over the last 10 years with most major high-income countries now recommending screening. This review describes the evidence base which has led to this, the current debate regarding choice of screening algorithm, and the future areas for further research.

Perfusion index in newborns with CHD without clinical signs of hypoperfusion and heart failure: comparison with healthy newborns

INTRODUCTION

Peripheral perfusion index has been proposed as a possible method for detecting circulatory impairment. We aimed to determine the normal range of peripheral perfusion index in healthy newborns and compare it with that of newborns with CHD.

METHODS

Right-hand saturation and right-hand peripheral perfusion index levels were recorded, and physical examination and echocardiography were performed in newborns who were 0-28 days old and whom were evaluated in our paediatric cardiology outpatient clinic. The saturation and peripheral perfusion index levels of newborns with normal heart anatomy and function were compared with those of newborns with CHD.

RESULTS

Out of 358 newborns (238 mature and 75 premature) enrolled in the study, 39 had CHD (20 mild CHD, 13 moderate CHD, and 6 severe CHD), of which 29 had CHD with left-to-right shunting, 5 had obstructive CHD, and 5 had cyanotic CHD. No newborn had clinical signs of hypoperfusion or heart failure, such as prolonged capillary refill, weakened pulses, or coldness of extremities. Peripheral perfusion index level was median (interquartile range) 1.7 (0.6) in healthy newborns, 1.8 (0.7) in newborns with mild CHD, and 1.8 (0.4) in newborns with moderate and severe CHD, and there was no significant difference between the groups regarding peripheral perfusion index level.

CONCLUSION

Peripheral perfusion index remains unchanged in newborns with CHD without the clinical signs of hypoperfusion or heart failure. Larger studies with repeated peripheral perfusion index measurements can determine how valuable this method will be in the follow-up of newborns with CHD.

Impact of pulse oximetry screening to detect congenital heart defects: 5 years' experience in a UK regional neonatal unit

Pulse oximetry screening (POS) has been shown to be an effective, non-invasive investigation that can detect up to 50-70% of previously undiagnosed congenital heart defects (CHDs). The aims of this study were to assess the accuracy of POS in detection of CHDs and its impact on clinical practice. All eligible newborn infants born between 1 Jan 2015 and 31 Dec 2019 in a busy regional neonatal unit were included in this prospective observational study. A positive POS was classified as two separate measurements of oxygen saturation < 95%, or a difference of > 2% between pre- and post-ductal circulations. Overall, 23,614 infants had documented POS results. One hundred eighty nine (0.8%) infants had a true positive result: 6 had critical CHDs, 9 serious or significant CHDs, and a further 156/189 (83%) infants had significant non-cardiac conditions. Forty-three infants who had a normal POS were later diagnosed with the following categories of CHDs post-hospital discharge: 1 critical, 15 serious, 20 significant and 7 non-significant CHDs. POS sensitivity for detection of critical CHD was 85.7%, whereas sensitivity was only 33% for detection of major CHDs (critical and serious) needing surgery during infancy; specificity was 99.3%.Conclusion: Pulse oximetry screening showed moderate to high sensitivity in detection of undiagnosed critical CHDs; however, it failed to detect two-third of major CHDs. Our study further emphasises the significance of adopting routine POS to detect critical CHDs in the clinical practice. However, it also highlights the need to develop new, innovative methods, such as perfusion index, to detect other major CHDs missed by current screening tools. What is Known: • Pulse oximetry screening is cost effective, acceptable, easy to perform and has moderate sensitivity and high specificity in detection of critical congenital heart defects. • Pulse oximetry screening has been implemented many countries including USA for detection of critical congenital heart defects, but it is not currently recommended by the UK National Screening Committee. What is New: • To our knowledge, this is the first study describing postnatal detection and presentation of all the infants with congenital heart defects over a period of 5 years, including those not detected on the pulse oximetry screening, on the clinical practice. • It emphasises that further research required to detect critical congenital heart defects and other major CHDs which can be missed on the screening tools currently employed in clinical practice.