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

Aim 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. Methods 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

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

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. 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. 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 2586 ± 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.

TO FIND OUT CORRELATION BETWEEN SVC FLOW AND LEFT VENTRICULAR OUTPUT IN NEWBORN BETWEEN GESTATIONAL AGE OF 34-37 WEEKS AND >37 WEEKS ON LIFE DAY ONE

Background: Preterm newborn is vulnerable to brain injury which is thought to be caused partly by abnormalities in cerebral perfusion (1). Commonly used parameters such as blood pressure & blood lactate level are not sufficient to detect low circulatory blood flow in preterm neonate because these are poor surrogate markers of systemic blood flow during the circulatory transition just after birth Methods- The Present Prospective Cross sectional observational study was conducted in the department of Paediatrics, attached to DR.SN Medical College Jodhpur over the duration of one year .Ethical consent was taken from local institutional ethical committee of Dr.S.N Medical College Jodhpur. Results: In present study 2D Echocardiography was done in preterm newborn (Median gestational age 35 week) (range 34-37 week ) on life day one for measurement of superior vena cava blood flow in which mean flow was 62.5±20.93 ml/kg/min (Mean±SD) and Median flow was 57.83ml/kg/min and range of SVC flow was 18-143 ml/kg/min. Also measured left ventricular output on life day one in which Mean±SD and median LVO flow was 204.88±70.74 and 189.5 which show r value 0.56 with significant positive predictive value <0.0001 by Pearson’s correlation coefficient. In term newborn between gestational ages of 37-41 week with Median gestational age 39 week (range 37-41 week) on life day one. In which mean LVO flow was 203.31± 61.88 (Mean±SD) and mean SVC flow was 58.89±19.11, (Mean±SD) Shows r value 0.40 and positive predictive value < 0.002 by using Pearson’s correlation coefficient. Conclusion: We conclude that SVC flow measurent through 2D colour Doppler echocardiography is most reliable and non-invasive method in preterm newborn as well as evaluation of treatment. . Although echocardiographic assessment of LVO appears to be relatively robust, it is of limited clinical value preterm neonates in the neonatal unit setting because the majority of sick preterm neonate will have patent ductus arteriosus, meaning that LVO does not represent systemic blood flow and is in fact a better marker of pulmonary flow volume. Keywords: SVC, Preterm, Term neonates.

Brief asphyxial state following immediate cord clamping accelerates onset of left-to-right shunting across the ductus arteriosus after birth in preterm lambs

Reversal of shunting across the ductus arteriosus from right-to-left to left-to-right is a characteristic feature of the birth transition. Given that immediate cord clamping (ICC) followed by an asphyxial cord clamp-to-ventilation (CC-V) interval may augment left ventricular (LV) output and central blood flows after birth, we tested the hypothesis that an asphyxial CC-V interval accelerates the onset of postnatal left-to-right ductal shunting. High-fidelity central blood flow signals were obtained in anesthetized preterm lambs (gestation 128 ± 2 days) after ICC followed by a nonasphyxial (∼40 s, n = 9) or asphyxial (∼90 s, n = 9) CC-V interval before mechanical ventilation for 30 min after birth. Left-to-right ductal flow segments were related to aortic isthmus and descending aortic flow profiles to quantify sources of ductal shunting. In the nonasphyxial group, phasic left-to-right ductal shunting was initially minor after birth, but then rose progressively to 437 ± 164 ml/min by 15 min ( P < 0.001). However, in the asphyxial group, this shunting increased from 24 ± 21 to 199 ± 93 ml/min by 15 s after birth ( P < 0.001) and rose further to 471 ± 190 ml/min by 2 min ( P < 0.001). This earlier onset of left-to-right ductal shunting was supported by larger contributions ( P < 0.001) from direct systolic LV flow and retrograde diastolic discharge from an arterial reservoir/windkessel located in the descending aorta and its major branches, and associated with increased pulmonary arterial blood flow having a larger ductal component. These findings suggest that the duration of the CC-V interval after ICC is an important modulator of left-to-right ductal shunting, LV output and pulmonary perfusion at birth. NEW & NOTEWORTHY This birth transition study in preterm lambs demonstrated that a brief (∼90 s) asphyxial interval between umbilical cord clamping and ventilation onset resulted in earlier and greater left-to-right shunting across the ductus arteriosus after birth. This greater shunting 1) resulted from an increased left ventricular output associated with a higher systolic left-to-right ductal flow and increased retrograde diastolic discharge from a lower body arterial reservoir/windkessel, and 2) was accompanied by greater lung perfusion after birth.

Agreement of Cardiac Output Measurements between Bioreactance and Transthoracic Echocardiography in Preterm Infants during the Transitional Phase: A Single-Centre, Prospective Study

<b><i>Introduction:</i></b> Bioreactance cardiac output (CO) monitors are able to non-invasively and continuously monitor CO. However, as a novel tool to measure CO, it must be proven to be accurate and precise. <b><i>Objective:</i></b> To determine the agreement between CO measured with a bioreactance monitor and transthoracic echocardiography-derived left ventricular output parameters in preterm infants. <b><i>Methods:</i></b> This is a prospective observational study in 63 preterm neonates with non-invasive respiratory support, not requiring inotrope support. The infants underwent continuous bioreactance monitoring of CO and stroke volume (SV) and simultaneous transthoracic echocardiography every 6 h until 72 h of life. <b><i>Results:</i></b> The agreement between bioreactance and transthoracic echocardiography, for both SV and CO, was poor. The percentage error was 67.5% for SV and 71.6% for CO. The mean error was 60.4% for SV and 69.8% for CO. Bias was affected by numerous variables. After correcting for time, CO and SV bias were significantly affected by the presence of an open patent ductus arteriosus and the level of CO. <b><i>Conclusion:</i></b> Bioreactance cannot be considered interchangeable with transthoracic echocardiography to measure CO in preterm infants during the transition phase. Agreement between bioreactance and other CO metrics should be assessed before concluding its accuracy or inaccuracy in neonates.

Myocardial function in late preterm infants during the transitional period: comprehensive appraisal with deformation mechanics and non-invasive cardiac output monitoring

Background:There is a paucity of functional data on mid-to-late preterm infants between 30+0 and 34+6 weeks gestation. We aimed to characterise transitional cardiopulmonary and haemodynamic changes during the first 48 hours in asymptomatic mid-to-late preterm infants.Methods:Forty-five healthy preterm newborns (mean ± standard deviation) gestation of 32.7 ± 1.2 weeks) underwent echocardiography on Days 1 and 2. Ventricular mechanics were assessed by speckle tracking-derived deformation, rotational mechanics, tissue Doppler imaging, and right ventricle-focused measures (tricuspid annular plane systolic excursion, fractional area change). Continuous haemodynamics were assessed using the NICOM™ system to obtain left ventricular output, stroke volume, heart rate, and total peripheral resistance by non-invasive cardiac output monitoring.Results:Right ventricular function increased (all measures p < 0.005) with mostly stable left ventricular performance between Day 1 and Day 2. NICOM-derived left ventricular output [mean 34%, 95% confidence interval 21–47%] and stroke volume [29%, 16–42%] increased with no change in heart rate [5%, −2 to 12%]. There was a rise in mean blood pressure [11%, 1–21%], but a decline in total peripheral resistance [−14%, −25 to −3%].Conclusion:Left ventricular mechanics remained persevered in mid-to-late premature infants, but right ventricular function increased. Non-invasive cardiac output monitoring is feasible in preterm infants with an increase in left ventricular output driven by an improvement in stroke volume during the transitional period.