Reference values of perfusion indices in hemodynamically stable newborns during the early neonatal period

Safety of different cord clamping strategies in the early postnatal period

BACKGROUND

This study aimed to evaluate the effect of ICC (cord clamping within the first 15 s), DCC (delayed cord clamping at 60 s), and cut-UCM (cut-umbilical cord milking, cord clamping within the first 15 s) groups on oxygen saturation (SpO2), heart rate (HR), and perfusion index (PI) up to 10 min after birth in newborn infants.

METHODS

We conducted this randomized clinical trial in the delivery unit of a University Hospital with 189 infants born between 35 and 42 weeks of gestation. Participants were randomly assigned to one of three groups: ICC, DCC, and cut-UCM. The primary outcomes measured were SpO2, HR, and PI at the 1st, 3rd, 5th, and 10th minutes after birth. We utilized ANOVA and Bayesian calculations in this study.

RESULTS

There was no difference between the ICC, DCC, and cut-UCM groups in SpO2, HR, and PI values at the 1st, 3rd, 5th, and 10th minutes of life, which did not significantly alter between the three groups in one-way ANOVA. Bayesian repeated-measure ANOVA calculations showed that SpO2 and heart rate results at the 1st, 3rd, 5th, and 10th minutes did not differ between ICC, DCC, and cut-UCM techniques with strong evidence. At the 3rd minute, PI was slightly higher in the DCC and cut-UCM groups compared to the ICC group, with anecdotal evidence. We found no difference between DCC and cut-UCM regarding the 3rd-minute PI, with moderate evidence.

CONCLUSION

Umbilical clamping procedures (ICC, DCC, and cut-UCM) did not affect SpO2 and HR in the first ten minutes of life, but 3rd-minute PI values were slightly higher in DCC and cut-UCM compared with ICC among late preterm and term neonates.

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.

Correlation between Perfusion Index and Left Ventricular Output in Healthy Late Preterm Infants

OBJECTIVE

The perfusion index (PI) is a noninvasive marker derived from photoelectric plethysmographic signals in pulse oximetry in the evaluation of peripheral perfusion. This study was aimed to determine the correlation between PI and left ventricular output (LVO) in healthy late preterm infants at 48th hour of life.

STUDY DESIGN

With new generation pulse oximeter (MASIMO Rad 7 Oximeter) pre- and post-ductal PI values were recorded from healthy late preterm babies at the 48th hour of life. PI was determined simultaneously with LVO as measured by transthoracic echocardiography.

RESULTS

A total of 50 late preterm babies were included in the study. The mean gestational age of the cases was 35.4 ± 0.7 weeks and the birth weight was 2,586 ± 362 g. Mean pre- and post-ductal PI values at the postnatal 48th hour of babies' life were found to be 2.0 ± 0.9 and 1.7 ± 1.1. The mean LVO value was 438 ± 124, LVO/kg 175 ± 50. When the LVO value was normalized according to the babies' body weight, there was no statistically significant correlation between the pre- and post-ductal PI and the LVO/kg value (r <0.2, p >0.05 in both comparisons).

CONCLUSION

There was no correlation between pre- and post-ductal PI and LVO values in healthy late preterm infants. This may be due to the failure of the LVO, a systemic hemodynamic parameter, to accurately reflect microvascular blood flow due to incomplete maturation of the sympathetic nervous system involved in the regulation of peripheral tissue perfusion in preterm babies.

KEY POINTS

· No correlation found between PI and LOV in preterm babies.. · LVO cannot adequately reflect peripheral blood flow.. · Sympathetic nervous system is immature in preterm infants..

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.

Is perfusion index a surrogate indicator of left ventricular contractility in neonates? A prospective study

Introduction

Noninvasive blood pressure monitoring may not accurately reflect cardiac contractility in neonates due to low vascular tone. The perfusion index (PI) is a noninvasive method of assessing the strength of peripheral pulses. It is shown to have a significant correlation with the left ventricular output. This prospective study estimates the correlation between PI and cardiac contractility in neonates.

Methods and Results

All hemodynamically stable neonates who were on substantial enteral feeds and not on any respiratory or inotropic support underwent measurement of PI and echocardiography examination. Various indices of left ventricular contractility were estimated, and the correlation coefficient between them and PI was determined. Fifty-six neonates were studied. The median (interquartile range [IQR]) PI was 1.5 (1.25-1.75). The median (IQR) PI in preterm neonates was 1.5 (1.2-1.8) and that in term neonates was 1.8 (1.25-2.7) (P = 0.064). PI had a correlation of 0.205 with fractional shortening (P = 0.129) and 0.13 with left ventricular ejection fraction (P = 0.821). The Spearman's correlation coefficient between PI and velocity of circumference fiber shortening was 0.009 (P = 0.945). The Spearman's correlation coefficient between PI and cardiac output was -0.115 (P = 0.400).

Conclusion

The PI does not correlate with left ventricular contractility parameters in neonates.

Peripheral perfusion index in well newborns at 6 to 72 h of life at different altitudes: a multi-center study in China

The purpose of this study is to obtain the reference range of peripheral perfusion index (PPI) of asymptomatic well newborns at 6 to 72 h of life at different altitudes. A population-based prospective cohort study was conducted in cities at different altitudes in China. Asymptomatic well newborns were enrolled consecutively from six hospitals with an altitude of 4 to 4200 m between February 1, 2020, and April 15, 2021. PPI was measured at 6, 12, 24, 48, and 72 h after birth on the right hand (pre-ductal) and either foot (post-ductal) using a Masimo SET Radical-7 oximeter. Fiftieth percentile reference curves of the pre- and post-ductal PPI values at 6-72 h after birth were generated using the Lambda Mu Sigma method. Linear mixed-effects regression was performed to determine the influence of different altitude levels on PPI values over different measurement time points. A total of 4257 asymptomatic well newborns were recruited for analysis. The median and quartile pre- and post-ductal PPI values at 6-72 h of life at different altitudes were 1.70 (1.20, 2.60) and 1.70 (1.10, 2.70) for all infants, 1.30 (1.10, 1.90) and 1.10 (0.88, 1.80) for infants at low altitude, 1.40 (1.00, 2.00) and 1.30 (0.99, 2.00) at mild altitudes, 1.90 (1.30, 2.50) and 1.80 (1.20, 2.70) at moderate altitudes, 1.80 (1.40, 3.50) and 2.20 (1.60, 4.30) for high altitudes, 3.20 (2.70, 3.70), and 3.10 (2.10, 3.30) for higher altitudes, respectively. Overall, both pre- and post-ductal PPI increased with altitude. The 50th percentile curves of pre- and post-ductal PPI values in well newborns at mild, low, moderate, and high altitudes were relatively similar, while the difference between the PPI curves of infants at higher altitudes and other altitudes was significantly different.  Conclusions: With the increase of altitude, pre- and post-ductal PPI of newborns increases. Our study obtained the PPI reference values of asymptomatic well newborns at 6 to 72 h after birth at different altitudes from 4 to ≥ 4000 m. What is Known: • Monitoring hemodynamics is very important to neonates. As an accurate and reliable hemodynamic monitoring index, PPI can detect irreversible damage caused by insufficient tissue perfusion and oxygenation early, directly, noninvasively, and continuously. What is New: • Our study obtained the PPI reference values of asymptomatic well newborns at 6 to 72 h after birth at different altitudes from 4 to ≥ 4000 m. With the increase of altitude, pre- and post-ductal PPI of newborns increase with statistical significance. Therefore, the values and disease thresholds of PPI for asymptomatic neonates should be modified according to altitudes.

Multimodal Assessment of Systemic Blood Flow in Infants

The assessment of systemic blood flow is a complex and comprehensive process with clinical, laboratory, and technological components. Despite recent advancements in technology, there is no perfect bedside tool to quantify systemic blood flow in infants that can be used for clinical decision making. Each option has its own merits and limitations, and evidence on the reliability of these physiology-based assessment processes is evolving. This article provides an extensive review of the interpretation and limitations of methods to assess systemic blood flow in infants, highlighting the importance of a comprehensive and multimodal approach in this population.

Peripheral Perfusion Index as a Marker of Sepsis in Preterm Neonates

BACKGROUND

Neonatal sepsis is a major contributor to neonatal mortality in India. Blood culture, the gold standard for the diagnosis of sepsis takes 48-72 h while the serological markers have suboptimal diagnostic test characteristics. Perfusion index (PI) is a real time, non-invasive marker that can detect microcirculatory changes before other clinical manifestation of sepsis.

OBJECTIVE

To determine the diagnostic accuracy of PI in detecting hospital-acquired sepsis before overt clinical manifestations.

STUDY DESIGN

A prospective observational study conducted in the Neonatal Intensive Care Unit (NICU) of a tertiary care hospital.

PARTICIPANTS

Preterm neonates admitted to NICU.

METHODS

PI was continuously monitored in all enrolled neonates. Clinical sepsis was defined using the NeonatalKrankenhaus-Infektions-Surveillance-System (NeoKISS). The time of fall of PI below 0.88 and time of clinical sepsis as per NeoKISS were noted and the difference was calculated.

RESULTS

Among 65 preterm neonates (gestational age: 31.5 ± 2.6 weeks, birth weight: 1350, IQR 1100-1700 g), a total of 86 events of suspected sepsis were noted, of which 69 were sepsis screen positive. Fifteen events were associated with culture positive sepsis. PI yielded a sensitivity of 89.47% (95% CI 78.48-96.04%), specificity of 56% (95% CI 34.93-75.60%), positive predictive value of 82.26% (95% CI 74.70-87.92%) and negative predictive value of 70% (95% CI 50.36-84.29%) in detection of hospital-acquired sepsis.

CONCLUSION

PI might serve as an early, non-invasive marker of hospital-acquired sepsis in preterm neonates.

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.

The perfusion index histograms predict patent ductus arteriosus requiring treatment in preterm infants

The impact of patent ductus arteriosus (PDA) on vital sign trends represented as histograms, and perfusion index in particular, is unknown. This study aimed to split continuously obtained PI and other vital signs before, during, and after medical treatment of PDA, into histogram bins, and determine the utility of PI and other vital sign histograms in the early prediction of hemodynamically significant PDA (hsPDA). In 34 infants at a mean gestational age of 26 ± 2.1 weeks, we prospectively collected vital signs for three different periods, 24 h before starting treatment of PDA, during PDA treatment, and 24 h after completion of the course of treatment, and confirmed PDA closure by echo. Histograms with three comparable periods were obtained from preterm infants who did not require treatment for PDA and analyzed for comparison. The duration of time spent in each histogram bin was determined for each time epoch. Episodes of low PI < 0.4 and high PI > 2 were significantly longer in duration in infants with PDA before treatment compared to those in infants with PDA during and after treatment. The arterial oxygen saturation (SpO₂) < 80% was also longer in duration in infants with PDA before compared to that in infants with PDA during and after treatment. Low PI < 0.4 correlated with most echocardiography indices of hsPDA.Conclusion: We conclude that a patent ductus arteriosus requiring treatment in preterm infants ≤ 29 weeks GA was associated with significant fluctuations between a low PI < 0.4 alternating with a high PI > 2, reflecting the dynamic nature of hsPDA shunt volume. PI variability may be an early marker of hsPDA. What is Known: • The perfusion index is a continuous underutilized parameter provided by pulse oximetry to assess the peripheral perfusion. • The perfusion index helps predict conditions with hemodynamic instability. What is New: • The perfusion index assessed as daily histogram trends can predict patent ductus arteriosus requiring treatment.

Signal Quality of Electrical Cardiometry and Perfusion Index in Very Preterm Infants

OBJECTIVE

The use of noninvasive monitoring of neonatal hemodynamics is increasing in neonatal care. Methods include noninvasive cardiac output estimated by electrical cardiometry (EC) and peripheral perfusion as perfusion index (PI) using pulse oximetry. Our aim was to evaluate the feasibility to continuously monitor preterm infants with EC and PI during the first 2 postnatal days and the effects of averaging EC data in signal quality (SigQ) analysis.

DESIGN

Prospective observational study.

SETTING

Tertiary neonatal academic hospital.

PATIENTS

Preterm infants <32 weeks gestation from birth until 48 h.

MAIN OUTCOME MEASURES

Continuous EC and PI measurements. Feasibility was quantified as the time with high SigQ, classified using SigQ index in EC and exception codes in PI. Our predefined threshold for good feasibility was minimum of 24 h with high SigQ for both.

RESULTS

Twenty-two preterm infants (median [IQR] gestational age 28 + 6 (26 + 0, 30 + 4) weeks + days, birth weight 960 [773, 1,500] g) were included. We recorded a minimum of 24 h with high SigQ in 14 infants for EC (unaveraged data) and 22 infants for PI measurements. The median (range) % of recording time with high SigQ was 74% (50%, 88%) for EC and 94% (82%, 96%) for PI. Using 1 minute averaging for EC data resulted in an increase of infants with minimum 24 h of high SigQ to 21 infants.

CONCLUSIONS

EC and PI monitoring are feasible in preterm infants within the first 48 h, but SigQ remains problematic for EC. Signal dropout is masked in averaged EC values.

What Inotrope and Why?

Primary function of cardiovascular system is to meet body's metabolic demands. The aim of inotrope therapy is to minimise adverse impact of cardiovascular compromise. Current use of inotropes is primarily guided by the pathophysiology of cardiovascular compromise and anticipated actions of inotropes. Lack of significant reduction in morbidity and mortality associated with cardiovascular compromise despite inotrope use, highlights major gaps in our understanding of circulatory targets, thresholds and choices of inotrope therapy. Thus far, prevention of cardiovascular compromise remains the most effective strategy to optimize outcomes. Studies of alternative design are needed for further advancement in cardiovascular therapy in neonates.

Peripheral perfusion index percentiles for healthy newborns by gestational age and sex in China

Peripheral perfusion index (PPI) percentiles for newborns serve as an important observation tool in clinical practice, but research pertaining to reference ranges are lacking. The aim of this study was to establish PPI percentiles for healthy newborns by gestational age and sex at 24-48 hours of life. We conducted an observational study and examined PPI values at 24-48 hours of life in 3814 asymptomatic newborns born between 35 and 41 weeks gestation who did not need medical treatment from June 1, 2016 to May 31, 2017 at two maternity hospitals in Shanghai. Linear regression analysis was carried out on the associations between PPI values and variables such as gestational age, sex, and birthweight. Pre-ductal PPI values linearly increased with gestational age (β: 0.072; 95% CI: 0.037, 0.107; P = 0.000). Post-ductal PPI values were also mainly related to gestational age (β: 0.051; 95% CI: 0.018, 0.085; P = 0.003). Smoothed reference curves for pre- and post-ductal PPI values by gestational age and sex were derived from LMS Chart Maker. Our study is the first study to establish PPI percentiles curves for healthy newborns by gestational age and sex at 24-48 hours of life. Further research is required for the implementation of PPI curves into clinical practice.

The value of peripheral perfusion index measurements for early detection of critical cardiac defects

BACKGROUND

Approximately 25% of congenital heart diseases (CHD) are estimated to be critical and require an intervention. In this study, we aimed to investigate the additional value of peripheral perfusion index (PPI) measurements to pulse oximetry screening for critical CHD (CCHD).

METHODS

Infants born at Ege University Hospital between May 2013 and September 2015 were prospectively included in the study. In addition to physical examination, pre- and postductal oxygen saturations and PPI values were measured with a new generation pulse oximeter before discharge from the hospital.

RESULTS

A total of 3175 newborns (33 with an antenatal diagnosis of CCHD) were included in the study. With the combination of physical examination, pulse oximetry screening and peripheral perfusion index (PPI) measurements, all newborns with CCHD were detected in our study including three infants without an antenatal diagnosis in whom pulse oximetry screening was negative.

CONCLUSION

PPI measurements may be valuable for early detection of obstructive left heart lesions where pulse oximetry screening has limitations in diagnosis.

Cerebral oxygen saturation and peripheral perfusion in the extremely premature infant with intraventricular and/or pulmonary haemorrhage early in life

Extremely preterm infants are at higher risk of pulmonary (PH) and intraventricular (IVH) haemorrhage during the transitioning physiology due to immature cardiovascular system. Monitoring of haemodynamics can detect early abnormal circulation that may lead to these complications. We described time-frequency relationships between near infrared spectroscopy (NIRS) cerebral regional haemoglobin oxygen saturation (CrSO₂) and preductal peripheral perfusion index (PI), capillary oxygen saturation (SpO₂) and heart rate (HR) in extremely preterm infants in the first 72 h of life. Patients were sub-grouped in infants with PH and/or IVH (N _H  = 8) and healthy controls (N _C  = 11). Data were decomposed in wavelets allowing the analysis of localized variations of power. This approach allowed to quantify the percentage of time of significant cross-correlation, semblance, gain (transfer function) and coherence between signals. Ultra-low frequencies (<0.28 mHz) were analyzed as slow and prolonged periods of impaired circulation are considered more detrimental than transient fluctuations. Cross-correlation between CrSO₂ and oximetry (PI, SpO₂ and HR) as well as in-phase semblance and gain between CrSO₂ and HR were significantly lower while anti-phase semblance between CrSO₂ and HR was significantly higher in PH-IVH infants compared to controls. These differences may reflect haemodynamic instability associated with cerebrovascular autoregulation and hemorrhagic complications observed during the transitioning physiology.

Correlations between near-infrared spectroscopy, perfusion index, and cardiac outputs in extremely preterm infants in the first 72 h of life

Haemodynamic assessment during the transitional period in preterm infants is challenging. We aimed to describe the relationships between cerebral regional tissue oxygen saturation (CrSO₂), perfusion index (PI), echocardiographic, and clinical parameters in extremely preterm infants in their first 72 h of life. Twenty newborns born at < 28 weeks of gestation were continuously monitored with CrSO₂ and preductal PI. Cardiac output was measured at H6, H24, H48, and H72. The median gestational age and birth weight were 25.0 weeks (24-26) and 750 g (655-920), respectively. CrSO₂ and preductal PI had r values < 0.35 with blood gases, lactates, haemoglobin, and mean blood pressure. Cardiac output significantly increased over the 72 h of the study period. Fifteen patients had at least one episode of low left and/or right ventricular output (RVO), during which there was a strong correlation between CrSO₂ and superior vena cava (SVC) flow (at H6 (r = 0.74) and H24 (r = 0.86)) and between PI and RVO (at H6 (r = 0.68) and H24 (r = 0.92)). Five patients had low SVC flow (≤ 40 mL/kg/min) at H6, during which PI was strongly correlated with RVO (r = 0.98).

CONCLUSION

CrSO₂ and preductal PI are strongly correlated with cardiac output during low cardiac output states. What is Known: • Perfusion index and near-infrared spectroscopy are non-invasive tools to evaluate haemodynamics in preterm infants. • Pre- and postductal perfusion indexes strongly correlate with left ventricular output in term infants, and near-infrared spectroscopy has been validated to assess cerebral oxygenation in term and preterm infants. What is New: • Cerebral regional tissue oxygen saturation and preductal perfusion index were strongly correlated with cardiac output during low cardiac output states. • The strength of the correlation between cerebral regional tissue oxygen saturation, preductal perfusion index, and cardiac output varied in the first 72 h of life, reflecting the complexity of the transitional physiology.

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

OBJECTIVE

To describe the distribution of perfusion index (PI) in asymptomatic newborns at 24 hours of life when screening for critical congenital heart disease (CCHD) using an automated data selection method.

DESIGN

This is a retrospective observational study.

SETTING

Newborn nursery in a California public hospital with ~3500 deliveries annually.

METHODS

We developed an automated programme to select the PI values from CCHD screens. Included were term and late preterm infants who were screened for CCHD from November 2013 to January 2014 and from May 2015 to July 2015. PI measurements were downloaded every 2 s from the pulse oximeter and median PI were calculated for each oxygen saturation screen in our cohort.

RESULTS

We included data from 2768 oxygen saturation screens. Each screen had a median of 29 data points (IQR 17 to 49). The median PI in our study cohort was 1.8 (95% CI 1.8 to 1.9) with IQR 1.2 to 2.7. The median preductal PI was significantly higher than the median postductal (1.9 vs 1.8, p=0.03) although this difference may not be clinically significant.

CONCLUSION

Using an automated data selection method, the median PI in asymptomatic newborns at 24 hours of life is 1.8 with a narrow IQR of 1.2 to 2.7. This automated data selection method may improve accuracy and precision compared with manual data collection method. Further studies are needed to establish external validity of this automated data selection method and its clinical application for CCHD screening.

Neurotoxicity versus Neuroprotection of Anesthetics: Young Children on the Ropes?

Normal brain development in young children depends on a balance between excitation and inhibition of neurons, and alterations to this balance may cause apoptosis. During the perioperative period, both surgical stimuli and anesthetics can induce neurotoxicity. This article attempts to expand the perspective of a topical issue-anesthetic-induced neurotoxicity-by also considering the protective effect of general anesthetics against surgery-induced neurotoxicity, all of which may generate some controversy in the current literature. The "new" major factor influencing neurotoxicity-nociceptive stimulus-is discussed together with other factors to develop clinical and research strategies to obtain a balance between neurotoxicity and neuroprotection.

Relationship between perfusion index and patent ductus arteriosus in preterm infants

BACKGROUND

Perfusion index (PI) is a noninvasive measure of perfusion. ΔPI (difference between pre- and postductal PI) may identify hemodynamically significant PDA. However, studies are limited to brief and intermittent ΔPI sampling. Our objective is to assess the value of continuous high resolution ΔPI monitoring in the diagnosis of PDA.

METHODS

Continuous ΔPI monitoring in preterm infants was prospectively performed using two high-resolution pulse oximeters. Perfusion Index measures (ΔPI mean and variability, pre- and postductal PI) were analyzed over a 4-h period prior to echocardiography. A cardiologist blinded to the results evaluated for PDA on echocardiography. Linear mixed regression models were utilized for analyses.

RESULTS

We obtained 31 echocardiography observations. Mean ΔPI (-0.23 vs. 0.16; P < 0.05), mean pre-PI (0.86 vs. 1.26; P < 0.05), and ΔPI variability (0.39 vs. 0.61; P = 0.05) were lower in infants with PDA compared to infants without PDA at the time of echocardiography.

CONCLUSION

Mean ΔPI, ΔPI variability, and mean pre-PI measured 4 h prior to echocardiography detect PDA in preterm infants. PI is dynamic and should be assessed continuously. Perfusion index is a promising bedside measurement to identify PDA in preterm infants.

Continuous noninvasive monitoring in the neonatal ICU

PURPOSE OF REVIEW

Standard hemodynamic monitoring such as heart rate and systemic blood pressure may only provide a crude estimation of organ perfusion during neonatal intensive care. Pulse oximetry monitoring allows for continuous noninvasive monitoring of hemoglobin oxygenation and thus provides estimation of end-organ oxygenation. This review aims to provide an overview of pulse oximetry and discuss its current and potential clinical use during neonatal intensive care.

RECENT FINDINGS

Technological advances in continuous assessment of dynamic changes in systemic oxygenation with pulse oximetry during transition to extrauterine life and beyond provide additional details about physiological interactions among the key hemodynamic factors regulating systemic blood flow distribution along with the subtle changes that are frequently transient and undetectable with standard monitoring.

SUMMARY

Noninvasive real-time continuous systemic oxygen monitoring has the potential to serve as biomarkers for early-organ dysfunction, to predict adverse short-term and long-term outcomes in critically ill neonates, and to optimize outcomes. Further studies are needed to establish values predicting adverse outcomes and to validate targeted interventions to normalize abnormal values to improve outcomes.

Perfusion Index in Very Low Birth Weight Premature Infants During Their First 2 Weeks of Life

BACKGROUND

Our program of research focuses on thermal and circulatory stability in extremely premature infants. In prior studies, we found that infants have long periods of time in which foot temperature (FT) is higher than central temperature. We thus wanted to determine whether blood flow in the foot is increased when FT is elevated. Perfusion index (PI) can be used as a clinical indicator of peripheral perfusion, but reports on use of PI in premature infants are lacking. We employed exploratory methodology to examine foot perfusion and temperature in very low birth weight infants.

AIMS

For premature infants after birth: (1) describe foot PI values for the first 2 weeks of life and (2) describe the relationship of longitudinal FT and PI.

STUDY DESIGN

Case study design with longitudinal FT and PI in 17 infants born at <29 weeks' gestation with birth weight < 1,200 g for 2 weeks after birth.

RESULTS

Infants averaged 851 g at birth and were 24-29 weeks' gestational age. The mean PI across all infants for 14 days was 1.04, SD = 0.79. Using a repeated measures multilevel model approach confirmed that FT and PI were positively related in these infants.

CONCLUSIONS

These findings demonstrate that perfusion is increased in the periphery in extremely premature infants when FT is increased. PI measures can be used as a trend for peripheral perfusion, and these values increase over the first 2 weeks of life in infants weighing more than 750 g.

Perfusion index assessment during transition period of newborns: an observational study

Background

Perfusion index (PI) is becoming a part of clinical practice in neonatology to monitor peripheral perfusion noninvasively. Hemodynamic and respiratory changes occur in newborns during the transition period after birth in which peripheral perfusion may be affected. Tachypnea is a frequent symptom during this period. While some tachypneic newborns get well in less than 6 h and diagnosed as “delayed transition”, others get admitted to intensive care unit which transient tachypnea of newborn (TTN) being the most common diagnosis among them. We aimed to compare PI of neonates with TTN and delayed transition with controls, and assess its value on discrimination of delayed transition and TTN.

Methods

Neonates with gestational age between 37 and 40 weeks who were born with elective caesarian section were included. Eligible neonates were monitored with Masimo Set Radical7 pulse-oximeter (Masimo Corp., Irvine, CA, USA). Postductal PI, oxygen saturation and heart rate were manually recorded every 10 s for 3 min for two defined time periods as 10^th minute and 1^st hour. Axillary temperature were also recorded. Newborn infants were grouped as control, delayed transition, and TTN.

Results

Forty-nine tachypneic (TTN; 21, delayed transition; 28) and 30 healthy neonates completed the study. PI values were similar between three groups at both periods. There were no correlation between PI and respiratory rate, heart rate, and temperature.

Conclusion

PI assessment in maternity unit does not discriminate TTN from delayed transitional period in newborns which may indicate that peripheral perfusion is not severely affected in either condition.

Rationale for Implementation of Warm Cardiac Surgery in Pediatrics

Cardiac surgery was developed thanks to the introduction of hypothermia and cardiopulmonary bypass in the early 1950s. The deep hypothermia protective effect has been essential to circulatory arrest complex cases repair. During the early times of open-heart surgery, a major concern was to decrease mortality and to improve short-term outcomes. Both mortality and morbidity dramatically decreased over a few decades. As a consequence, the drawbacks of deep hypothermia, with or without circulatory arrest, became more and more apparent. The limitation of hypothermia was particularly evident for the brain and regional perfusion was introduced as a response to this problem. Despite a gain in popularity, the results of regional perfusion were not fully convincing. In the 1990s, warm surgery was introduced in adults and proved to be safe and reliable. This option eliminates the deleterious effect of ischemia-reperfusion injuries through a continuous, systemic coronary perfusion with warm oxygenated blood. Intermittent warm blood cardioplegia was introduced later, with impressive results. We were convinced by the easiness, safety, and efficiency of warm surgery and shifted to warm pediatric surgery in a two-step program. This article outlines the limitations of hypothermic protection and the basic reasons that led us to implement pediatric warm surgery. After tens of thousands of cases performed across several centers, this reproducible technique proved a valuable alternative to hypothermic surgery.

The perfusion index of healthy term infants during transition at birth

Perfusion index is a continuous parameter provided by pulse oximetry and might be useful for evaluating hemodynamic changes at birth and identifying transitional problems. The objective was to describe perfusion index values in term infants immediately after birth. Perfusion index of 71 healthy term born infants were recorded during the first 10 min after birth, using a pulse oximetry sensor placed preductally. A Wilcoxon signed-rank test was used to compare between time points. No significant trend in perfusion index could be observed in term-delivered infants. There was a significant difference between 2 and 3 min (2.4 (1.6-5.0) vs. 2.3 (1.6-3.7), p = 0.05) and between 3 and 4 min after birth (2.3 (1.6-3.7) vs. 2.1 (1.4-3.2), p < 0.001). There was no significant change in median PI values in the following 8 min.

CONCLUSION

Perfusion index does not change significantly during transition at birth in healthy term infants born by normal vaginal delivery or cesarean section. Large variation in perfusion index causes monitoring this parameter to have limited value.

WHAT IS KNOWN

• Perfusion index is a non-invasive indicator for peripheral perfusion. • Perfusion index values <1.24 are seen as an accurate predictor for severity of illness for infants admitted to the neonatal intensive care unit. What is new: • Although significant physiological changes occur during birth, perfusion index remains stable. • Large variation in perfusion index causes monitoring of this value to have limited value as an additional parameter for evaluating transition at birth.

Enhanced Monitoring of the Preterm Infant during Stabilization in the Delivery Room

Monitoring of preterm infants in the delivery room (DR) remains limited. Current guidelines suggest that pulse oximetry should be available for all preterm infant deliveries, and that if intubated a colorimetric carbon dioxide detector should provide verification of correct endotracheal tube placement. These two methods of assessment represent the extent of objective monitoring of the newborn commonly performed in the DR. Monitoring non-invasive ventilation effectiveness (either by capnography or respiratory function monitoring) and cerebral oxygenation (near-infrared spectroscopy) is becoming more common within research settings. In this article, we will review the different modalities available for cardiorespiratory and neuromonitoring in the DR and assess the current evidence base on their feasibility, strengths, and limitations during preterm stabilization.

Perfusion index in the preterm infant immediately after birth

AIM

To evaluate PI in preterm infants during the first 10 min of life.

DESIGN/METHODS

An observational study was conducted in the delivery room on preterm infants (less than 32 week gestation). PI values were obtained from a pre ductal saturation probe placed on the right wrist. Analysis was performed on the first 10 min of data to investigate the correlation of PI with gestational age, heart rate, blood pressure, and lactate values.

RESULTS

33 infants with a median gestational age of 29 wks (IQR, 26-30 wks) and median birth weight of 1205 g (IQR, 925-1520 g) were included for analysis. The overall median PI value for the first 10 min was 1.3 (IQR, 0.86-1.68). There was no significant correlation found between delivery room PI and gestational age(r=0.28, 95% CI: -0.09, 0.59), lactate levels (r=-0.25, 95% CI: -0.62, 0.18) and blood pressure values (r=-0.18, 95% CI: -0.46, 0.20). An average correlation value of r=-0.417 (95% CI: - 0.531, -0.253) was found between PI and heart rate values. There was no statistical difference between the median of the median PI value over the first 5 min of life compared to the second 5 min (p=0.22). Variability, as quantified by the IQR, was higher in the first 5 min compared to the second 5 min: median of 0.5(IQR, 0.27, 0.92) vs 0.2(IQR, 0.10, 0.30) (p<0.00).

CONCLUSIONS

Delivery room PI values are easily obtained, however, have significant variability over the first 5 min of life and may add little to delivery room assessment.