Arterial Blood Pressure and Cerebral Tissue Oxygenation During Immediate Transition After Birth in Term and Preterm Neonates - a Prospective Pilot Observational Study
Conditions: Blood Pressure, Cerebral Tissue Oxygenation
Sponsor: Medical University of Graz

Protocol Version 1.2  
05th, May, 2022 
 
 
 
Arterial blood pressure and cerebral tissue oxygenation during immediate 
transition after birth in term and preterm neonates – a prospective pilot 
observational study 
 
 
 
 
Daniel David Pfurtscheller, MD, Gerhard Pichler, MD 
Research Unit of Neonatal Micro- and Macrocirculation (Head: Prof. Dr. G Pichler), 
Department of Pediatrics, Medical University of Graz, Auenbruggerplatz 30, 8036 Graz, 
Austria 
 
 
Keywords: preterm infant, transition, near infrared spectroscopy, regional cerebral oxygen 
saturation, supplemental oxygen, blood pressure, cardiac output 
 
 
 
 
Address for correspondence: 
Dr.med. univ., Cand med sci. student:  
Daniel David Pfurtscheller, MD 
Klinische Abteilung für Neonatologie 
Univ. Klinik für Kinder- und Jugendheilkunde 
Medizinische Universität Graz 
Auenbruggerplatz 30 
8036 Graz 
Phone: +43-316-385-30452 
Fax: +43-316-385-2678 
Mail:    DanielDavid.Pfurtscheller@uniklinikum.kages.at 

 
1. Background 
 
1.1 Clinical assessment immediately after birth 
Evaluation of a newborn infant immediately after birth could be a challenge. To standardize 
the clinical assessment Virginia APGAR introduced 1953 the so-called APGAR-Score, which 
is still used routinely worldwide, to evaluate the neonates in the delivery room. (1). 
 
1.2 Monitoring immediately after birth 
The latest resuscitation guidelines recommend in addition to the clinical assessment  to monitor 
arterial oxygen saturation (SpO2) and heart rate (HR) immediately after birth in neonates 
in need of support (2). 
However, since 1953 beside SpO2 and HR monitoring, further methods and parameters, 
which could be monitored have been described during the immediate transition after birth that 
might help to assess the neonate in this crucial period. These methods include cardio- 
circulatory monitoring of blood pressure or cardiac output (3–5), respiratory function 
monitoring (6), transcutaneous monitoring of pCO2 (7) and cerebral monitoring with (a)EEG 
or near infrared spectroscopy (NIRS) (10, 11). 
 
1.3 Cardio-circulatory monitoring during immediate transition 
Blood pressure on the one hand is a routine monitoring in the NICU measured invasively or 
with the oscillometric method non-invasively. During immediate neonatal transition in the 
delivery room, the invasive measurement is not feasible, whereby the oscillometric method 
has already been proven to be feasible. (13). Meanwhile, reference ranges for non-invasively 
measured arterial blood pressure have been published for preterm and term neonates (14). 
Cardiac output on the other hand can be measured with noninvasive, minimal invasive and 
invasive methods (18). The gold standard method would be the so-called thermodilution 
technic, which is gained through a pulmonary vain catheter that is, however, quite invasive 
(19, 20). Cardiac output measurements  are therefore performed routinely with the 
echocardiography especially in severely ill neonates in the NICU. The advantage of the 
echocardiography is that it is a non-invasive method and the disadvantages are that the quality 
of the echocardiography depends on the experience of the examiner and evaluation is non- 
continuous. Furthermore, the measurement itself has its limitation concerning feasibility when 
performed during resuscitation (4, 21, 22). 

A further method to measure cardiac output is the electrical velocimetry. This method is 
based on the different electrical conductivity of certain biological tissues. Due to impedance 
changes during a heartbeat, the stroke volume can be assessed, and the cardiac output calculated 
(8). Electrical velocimetry monitoring is a feasible new method to measure cardiac output 
during the immediate transition after birth (9). Noori et al. showed that electrical velocity 
monitoring has regarding the cardiac output comparable results to echocardiography (12). 
 
1.4 Near-infrared spectroscopy (NIRS) 
NIRS was first described and published by Jöbsis (23) in 1977. The basis of this technique are 
the physical properties of the organic tissue to light in the near infrared region. The light used 
has therefore a wavelength in the near infrared region (700-1000 nm) (11). This light is 
absorbed, scattered or reflected differently by different chromophores such as myoglobin, 
cytochrome oxidase, oxygenated or deoxygenated hemoglobin in the biological tissue. Due to 
this, it is possible to monitor continuously the tissue oxygenation that depends on oxygen 
supply as well as the consumption of different tissues such as brain, kidney, or muscles (11, 
24, 25). 
NIRS therefore is a continuous noninvasive monitoring of tissue oxygenation that reflects the 
tissue oxygen saturation in veins, capillaries, and arteries of the measured compartment (10, 
25, 26). 
With the knowledge of the SpO2 and the tissue oxygen saturation the fractional tissue oxygen 
extraction (FTOE) can be calculated (FTOE=(SpO2-tissue oxygenation/SpO2). FTOE reflects 
the oxygen extraction of a tissue from the vessels, which helps to assess the activity of certain 
biological tissues (25, 27). 
 
1.5 Arterial blood pressure, cardiac output and cerebral oxygenation 
The tissue oxygen saturation is not only depending on the SpO2 but also on the hemoglobin 
content of the blood, the perfusion and tissue oxygen consumption. Concerning the perfusion 
and considering the brain it would be the so-called cerebral blood flow (CBF), which depends 
on cerebral perfusion pressure (CPP). CPP is defined as the difference between intracranial 
pressure (ICP) and mean arterial blood pressure (MABP) (28–30). During immediate 
transition ICP measurement is not feasible due to the invasive technics through a catheter and 
ICP can be assumed to be constant during the transition period especially in preterm neonates 
where the sutures are not closed yet. In contrast to that, the MABP can easily be measured 

even during the immediate transition non-invasively with an oscillometric method as 
discussed previously (13). 
MABP itself depends mainly on CO and vascular resistance. In the peripheral tissue, i.e. 
muscle, an increase of the MABP correlates well with an increase of oxygenated hemoglobin. 
The correlation between the MABP and the cranial perfusion and oxygenation should be 
weaker, due to cerebrovascular response mechanism, known as cerebral autoregulation that 
should keep cerebral perfusion constant independently of MABP (31). 
In sick neonates and in preterm neonates, however this autoregulation is not working as well 
as in healthy term infants (15, 17). 
 
1.6 Physiological changes of the cardio—circulatory system during transition 
The main difference of fetal cardio-circulation to the cardio-circulation after birth is that 
before birth the lungs are by-passed, and the oxygenated blood is provided by the placenta. 
The three bypasses are the ductus venosus (DV), a connection between the umbilical vein and 
the vena cava inferior, the ductus arteriosus (DA), a vessel between pulmonary artery and the 
aorta to avoid pulmonary circulation, and the foramen ovale (FO), a connection between the 
cardiac atria which also serves the purpose to bypass the pulmonary circulation. 
Due to these described peculiarities the fetal circulation is a parallel circulation instead of a 
serial one (32, 33). 
During transition, the pulmonary resistance drops, due to the lung aeration. This resistance- 
drop triggers an increase of the pulmonary blood-flow. Considering this new detour, 
depending on when the umbilical cord was clamped, the preload is reduced during the first 
minutes after birth. Furthermore, due to the cord clamping the low-resistance placenta 
circulation is yield, which leads to an increased afterload and the arterial pressure increases. 
As a result of reduced preload and initial-increased afterload, the cardiac output is reduced 
with clamping the cord. 
Considering these changes, the cerebral blood-flow as well as the systemic blood flow and 
systemic blood pressure are initially increased whereby a drop occurs immediately after the 
initial increase due to the reduced cardiac output (34). Afterwards, the cardiac output continues 
to stay low until the pulmonary blood-flow increases with ventilation of the lungs (35). During 
this cardio-circulatory and pulmonary changes immediately after birth the cerebral auto-
regulatory mechanisms should maintain the cerebral blood-flow constant. These autoregulatory 
mechanisms are not yet fully comprehensible especially in preterm neonates (36, 37). 

In term neonates Baik et al have demonstrated that cFTOE as well as crSO2 are independent 
of MABP (38, 39). However, Baik’s study (38) only investigated MABP in connection with 
crSO2 as well as cFTOE 15 minutes after birth. However, the question remains, if in term 
neonates MABP has some influence on cerebral oxygenation before minute 15 after birth 
when the lung is aerated, and most cardio-circulatory changes take place. 
Furthermore, Baik’s study (38) showed a significant negative correlation between MABP and 
cFTOE in preterm neonates which seems to suggest that in preterm infants the autoregulatory 
mechanism are less mature than in term neonates and that preterm neonates may benefit from 
blood pressure monitoring during immediate neonatal transition. These findings are in 
accordance with the animal model of Helou and Rhees observation in neonates (15–17). 
However again the question remains, if in preterm neonates MABP has more influence on 
cerebral oxygenation before minute 15 after birth when the lung is aerating and most cardio- 
circulatory changes take place. 
 
 
2 Aims 
 
2.1 Primary aim 
The primary aim of the present study is therefore to investigate if there is an influence of 
blood pressure on cerebral oxygen saturation and cerebral oxygen extraction within the first 
minutes (within 15 minutes) after birth in term and preterm neonates, when most cardio- 
circulatory changes and aeration of the lung take place. 
 
2.2 Secondary aim 
Secondary aims are to investigate a possible influence of cardiac output on cerebral oxygen 
saturation and cerebral oxygen extraction within the first minutes after birth in term and 
preterm neonates and any possible differences between term and preterm neonates. 
 
 
 
3. Hypotheses: 
 
3.1 Primary Hypothesis I 
Non-invasive measured blood pressure correlates with cerebral oxygen saturation and cerebral 
fractional oxygen extraction, whereby higher blood pressure is associated with higher cerebral 

oxygen saturation and lower cerebral fractional oxygen extraction in term and preterm neonates 
within the first 15 minutes after birth. 
 
3.2 Secondary Hypotheses II 
Cardiac output correlates with cerebral oxygen saturation and cerebral fractional oxygen 
extraction, whereby higher cardiac output is associated with higher cerebral oxygen saturation 
and lower cerebral fractional oxygen extraction, whereby correlations are more pronounced in 
preterm neonates within the first 15 minutes after birth. 
 
 
4 Patients and Methods 
 
4.1 Patients 
Term and preterm neonates observed routinely at the resuscitation desk at the Division of 
Neonatology, Department of Pediatrics, Medical University of Graz after caesarean section 
and/or who require respiratory support will be eligible for the study. CPAP and PPV with 
mask, if necessary, will be performed with Neopuff Infant Resuscitator (Fisher&Paykel 
Healthcare, New Zealand). 
The total number of birth/year at the Department of Obstetrics and Gynecology, Medical 
University of Graz is approximately 3000 - of these are around 8-10% preterm neonates. 
The antepartum medical history and birth history will be collected. Gestational age, birth 
weight, gender, Apgar score, ph of umbilical artery and postnatal blood gases (if routinely 
analyzed) will be documented in each neonate. 
 
4.1.1 Inclusion criteria 
▪ Term and preterm neonates observed routinely at the resuscitation desk 
▪ Decision to conduct full life support 
▪ Written informed consent 
 
 
4.1.2 Exclusion criteria 
▪ No decision to conduct full life support 
▪ No written informed consent 
▪ Congenital malformation 
 
 
4.1.3 Patient groups 
1. Preterm neonates (<37+0 weeks of gestation) 

2. Term neonates (≥37+0 weeks of gestation) 
 
 
5 Sample size 
In preterm infants, it was found that the correlation between MABP, and cFTOE is r = -0.19 at 
15 minutes after birth. Even lower correlations were found for crS02 and MABP and for term 
infants (38). Due to the bevor in 1.6. described changes during the immediate transition period, 
which lead to a decrease in cardiac preload and an increase in cardiac afterload the cardiac 
output is reduced. Considering these changes in the cerebral blood flow as well as the 
systemic blood flow and systemic blood pressure we expect to find higher correlations in the 
fifth and tenth minute after birth. According to our experience, it is feasible to include 50 
infants in this study. If 50 infants are included and a drop-out rate of 10% is considered, 45 
infants can be analyzed. Using these 45 infants the lower limit of Spearman’s rank correlation 
coefficient’s 95% CI will be 0.14 for a correlation coefficient of r = 0.40. This lower limit 
increases to 0.20, 0.26, 0.32 for r = .45, r = .50 and r= .55 respectively.  
Therefore we aim for a sample size of 50 neonates in each group – prterm neonates and term 
neonates, resulting in a total sample size of 100 neonates  
 
6 Study design 
 
Prospective observational pilot study 
 
7 Monitoring 
 
7.1 Routine Monitoring 
SpO2, heart rate, and central temperature will be monitored routinely. In addition, if CPAP or 
PPV are required non-invasive respiratory-function monitoring and transcutaneous pCO2 as 
routine non-invasive monitoring will be performed in the first minutes of resuscitation. 
Routine monitoring: 
1) Pulse oximetry (MR7CDS1 Radical 7, Chemomedica, Austria / IntelliVue MP70, Philips, 
Netherland) 
2) Peripheral and central temperature (IntelliVue MP70, Philips, Netherland) 
3) Respiratory function monitor (Monivent) 
4) pCO2 (TC Sensor 84, etC02 Sensor, Radiometer RSCH GmbH, Thalwil, Switzerland / 
IntelliVue MP70, Philips, Netherland) 
 

7.2 Additional Monitoring 
In addition during the first 15 minutes we will record: NIRS measurements, non-invasive 
blood pressure and cardiac output. 
 
Additional Monitoring: 
5) NIRS (t-NIRS, Hamamatsu, Japan) 
6) Blood pressure measurement (IntelliVue MP70, Philips, Netherland) 
7) Cardiac Output (Aesculon-EV-Monitor, Osypka, Berlin, Germany) 

 
7. 3 NIRS - cerebral regional oxygen saturation- tissue oxygenation index  
For NIRS measurements the t-NIRS device (Hamamatsu, Japan ) will be used. This monitor 
uses a “time resolved” technique and measures non-invasively oxygenated, deoxygenated and 
total hemoglobin and tissue oxygenation index (TOI that corresponds to cerebral regional 
oxygen saturation). 
Immediately after birth when the neonate is brought to the resuscitation desk, a sensor will be 
placed and fixed with a CPAP cap on the left forehead. 
 
7.4 Blood pressure   
For non-invasive blood pressure measurements the IntelliVue MP50 monitor (Philips, 
Netherland) will be used. The pneumatic cuff will be placed around the left upper arm and 
blood pressure measurements will be performed during the first fifteen minutes after birth. 
  
7.5 Cardiac output Monitoring  
For non-invasive cardiac-output measurements the Aesculon-Monitor (Osypka, Berlin, 
Germany) will be used. The monitor uses a new technique of thoracic bioimpedance. Four 
surface EKG electrodes are placed over the skin (forehead, left side of the neck, left hemithorax 
and left thigh). 
 
8 Routine Interventions 
Resuscitation will be according the “European Consensus Guidelines” on the management of neonatal 
respiratory distress syndrome (2). 
 
 
 
9 Outcome measures 
 
9.1 Primary 
▪ 
Blood pressure minute 5, 10 and 15 
▪ 
NIRS data measured with t-NIRS minute 5, 10 and 15 
▪ 
FTOE minute 5, 10 and 15 
 
 
9.2 Secondary 
▪ 
Cardiac output minute 5,10 and 15 
▪ 
Gestational age 

 
9.3 Exploratory 
▪ 
Respiratatory support during resuscitation 
▪ 
SpO2 level at each minute 
▪ 
HR level at each minute 
▪ 
Temperature minute 5 and 15 
▪ 
Monitoring parameters during the first 15minutes after birth: 
▪ 
Mean (SD) HR 
▪ 
Mean (SD) BP 
 
 
 
10 Outcome assessment tools 
 
Monitoring during the first 15 minutes after birth 
 
Medical history 
 
Severe morbidities and all cause mortality will be recorded 
 
 
 
 
11 Risks and benefits 
Pulse oxymetry the recommended routine monitoring will be performed in all neonates and 
SpO2 will be kept within normal ranges (10th-90th centile) (2) in all neoantes hypoxygenation 
and hyperoxygenation defined by the routine monitoring should be avoided. Blood 
measurements are routine in neonates in the NICU and well tolerated. Irritation of the skin 
due to the NIRS and the Aesculon-Monitor sensors is improbable, because of the short 
measurement period. Risks related to the manipulation of the patient during positing and re- 
positing of the sensors will be minimized by experience of research team. Neonates will 
always be under routine monitoring and observation by nurses and neonatologists. 
 
 
 
 
 
12 Informed consent procedure 
Parents of potential participants will be invited to enroll their preterm newborn, when possible, 
before delivery. The qualified physician will make contact and parents will be informed of the 
study and given the Parent information sheet. The parents will be given time to think and ask 

questions, before a written informed consent can be obtained. Parents will be given a copy of 
the informed consent. 
 
 
13 Data collection 
NIRS data and other monitoring data (SpO2, HR, tcpCO2, and temperature) will be collected 
in a polygraphic system (alpha-trace digital MM, B.E.S.T. Medical Systems, Austria). Blood 
pressure, demographic and medical history data will be anonymized and collected with a 
CRF. 
 
 
14 Data analysis 
Initially, all data will undergo a descriptive analysis to uncover any data anomalies and 
missing values that may impact the validity of the data analysis. 
Demographic, NIRS and routine monitoring data will be presented as n (%), mean and 
standard deviation (SD), or median and interquartile range (IQR), as appropriate. 
Comparisons of categorical characteristics between preterm and term infants will be 
performed using chi-square test and for continuous variables using t-test or Mann-Whitney U- 
test, as appropriate. 
Correlation analyses will be performed to investigate, if there is a connection between 
crSO2, cFTOE and MAP in preterm and term infants at different time points, individually. 
Correlations will be performed using Spearman's rank correlation coefficient or Pearson's 
correlation when appropriate. A p-value < 0.05 will be considered statistical significant. The 
statistical analyses will be performed using IBM SPSS Statistics 22.0.0 (IBM Corporation; 
Armonk, USA). 
Comparison of correlation analyses at different time points and in term and preterm neonates 
will be descriptive.Statistical analysis is planned to be performed in cooperation with the 
Institute for Medical Informatics, Statistics and Documentation, Medical University of Graz, 
Austria. 
 
 
 
 
Graz, 0.5.05.2022 

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