Copeptin- Relevance as a Perioperative Marker in Pediatric Cardiac Surgery
Conditions: Congenital Heart Disease
Sponsor: Claudia Herbst

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PROJECT SCHEDULE 
 
Copeptin- Relevance as a Perioperative Marker in Pediatric Cardiac Surgery 
 
Erhan Urganci 
n1150639 
 
 
Department of Cardiac Surgery 
Medical University of Vienna 
Währinger Gürtel 18-20, 
1090 Vienna, Austria 
 
 
Supervisor: 
Dr. med. univ. Claudia Herbst 
claudia.herbst@meduniwien.ac.at 
 
 
 
Dr. med. univ. Claudia Herbst, MD 
 

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TABLE OF CONTENT 
 
1.  
1. Summary  
3 
2. Background 
4 
3. Aims of this study 
6 
4. Study population 
6 
5. Methods 
7 
6. Statistical analysis 
8 
7. Ethical aspects 
9 
8. Data handling and record keeping 
10 
9. Time schedule 
10 
10. Additional contributers 
11 
References 
11 
2.  
 
 
 
 

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1. Summary  
 
Objective: 
Vasopressin is a hormone secreted by the posterior pituitary gland. Its main 
functions are the constriction of blood vessels and reabsorption of water and 
thereby regulating water balance and hemodynamics of the body. Copeptin is a 
cleavage product in the synthesis of vasopressin and is being released in 
equimolar amounts. Its stability makes it easier to determine than vasopressin.  
The use of a heart-lung machine in cardiac procedures has important effects on 
the water balance of the body and affects vasopressin secretion. 
This prospective clinical trial aims to figure out if copeptin would be suitable for 
perioperative risk evaluation in neonates and children with congenital heart 
disease after surgery with the use of a heart-lung machine.  
Hypotheses: 
The primary outcome endpoint of this study is the change in copeptin 
concentration perioperatively in patients with congenital heart disease, with the 
use of heart-lung machine. 
Secondary outcome endpoints are correlations between copeptin concentration 
and complexity of the procedure (based on the aristotle basic score), clinical 
status and the perfusion times of the heart-lung machine. 
Material and Methods:  
The study population consists of 81 subjects, newborns, infants and children   
up to six years of age with congenital heart disease, undergoing surgery with 
the use of a heart lung machine.  
To determine the main outcome variable, three blood samples will be taken 
from each patient perioperatively in order to evaluate changes in copeptin 
concentration.  

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Relevance and Implications:  
This will be the first study focusing on correlations of copeptin concentrations 
with different variables in pediatric cardiac surgery. Findings may allow to use 
copeptin perioperatively to evaluate the clinical and hemodynamic situation of 
patients after congenital heart surgery. 
 
2. Background 
 
Vasopressin - Synthesis and Secretion: 
Vasopressin is a polypeptid built of 9 amino acids. It is synthesized in the 
magnocellular neurons, the paraventricular nucleus and supraoptic nucleus of 
the anterior hypothalamus. These neurons have axonal projections which 
connect to the posterior pituitary gland were the hormone is carried through. 
After posttranslational processing the product, prepro-AVP-NPII, is being 
cleaved by endopeptidases into AVP, neurophysin II (95 amino acids) and 
copeptin (39 amino acids) in equal amounts. By opening voltage-gated calcium 
channels, neurosecretory granules start fusioning with the nerve terminal 
membrane and release AVP, NPII and copeptin in equimolar amounts into the 
circulation. 
Neurophysin and copeptin have no known role in peripheral tissues. Since both 
polypeptides are being released in equal amounts, copeptin can be used as a 
reliable surrogate marker for vasopressin secretion.  
Studies also showed that copeptin is elevated in critically ill patients, after 
myocardial infarction, septic shock and chronic heart failure. 
 
 
Cellular Action 
Vasopressin binds to G-protein-coupled receptors called vasopressin receptors 
that are classified into V1, V2 and V3 subtypes. The V1 receptor is found in 
vascular smooth muscle, liver, platelets and central nervous system and is Gq- 
mediated and therefore results in an increase of intracellular calcium which 
leads to vasoconstriction. The V2 receptor is expressed on the basolateral 
membrane of the collecting ducts of the kidney and stimulates movement of 
aquaporin-2 to the apical membrane, which allow reabsorption of water. The V3 

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receptor is found in the anterior pituitary gland and acts synergistically with CRF 
causing secretion of ACTH. 
 
 

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Copeptin 
The measurement of AVP is technically challenging because of its instability 
and the large amount attached to platelets. Therefore copeptin is used as a 
surrogate marker. It can be measured in serum and plasma samples by 
sandwich immunoassay. Its ex vivo stability for at least 7 days in serum and 
citrate-, EDTA-, and heparin plasma at 4°C was demonstrated. Studies also 
showed that there is no association in copeptin levels with age. 
 
Heart-Lung Machine 
The heart-lung machine takes up the perfusion work of the heart and 
additionally oxygenates the carried blood. It is a vital tool in cardiac surgery and 
enables complex procedures to be performed. 
It is important to pay close attention to the effects of the heart-lung machine in 
the postoperative period including: volume shift from intravasal to interstitial, 
peripheral vasoconstriction, myocardial depression and altered hemodynamics 
without adaption to recent flow conditions. Therefore it also affects synthesis 
and secretion of vasopressin. 
 
3. Aims of this study 
This prospective clinical trial aims to assess changes in copeptin levels 
perioperatively in patients with congenital heart disease undergoing corrective 
or palliative surgery with the use of a heart-lung machine by analysis of three 
blood samples of each patient. 
 
4. Study population 
The study population consists of 81 patients (neonates, infants, children) with 
congenital heart disease and the need of surgery with a heart-lung machine. 
Parental consent after pre-operation discussion and informing of the study is 
required.  
Exclusion criteria are following: need of preoperative mechanical circulatory 
support, preoperative mechanical ventilation, Diabetes insipidus, preoperative 
cardio pulmonary resuscitation, no consent of the parents and preoperative 
shock or sepsis. 

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5. Methods 
After induction of anesthesia every patient undergoing cardiac surgery will get 
monitored by vascular access. The anesthesiologist will place an arterial 
catheter for invasive blood pressure and a central venous catheter for applying 
medication and measurement of central venous pressure. We are planning to 
use these catheters for taking the blood samples which means that we will not 
place an additional syringe for the study.  
For measurement of copeptin 900µl of blood is taken at three different time 
points. The first sample will be taken before the surgery in the operation room. 
The second sample will be taken after the surgery in the operation room and the 
third sample, one day after the surgery in the intensive care unit. The exact 
times will be recorded in report sheets.  
After the surgery the cardiopulmonary bypass times and the exact procedures 
will be recorded. The performed procedures are needed in regard to calculating 
the Aristotle score which determines the complexity of the procedure.  
The extubation time and the lenght of stay in the intensive care unit as well as 
any important events (any complications) in the postoperative period are going 
to be recorded. 
The samples will be stored at the Meduni Wien Biobank until all samples are 
collected. After collection of these data for 81 patients the samples will be 
analyzed by the laboratory and the collected data will be prepared for statistical 
analysis.  
 
Sample size 
Sample size calculation was performed based on a paired t-Test. Due to a prior 
study we knew that the major change of copeptin concentration would be 
between the first and second measurement. Assumptions of the needed 
variables were estimated based on this study. 
As a result a sample size of 73 patients will have 80% power to detect a 
difference in means of -0,25 (e.g. a first condition mean, m1, of 0,086 and a 
second condition mean, m2, of 0,336), assuming a standard deviation of 
differences of 0,75, using a paired t-test with a 0,05 two-sided significance level. 
Based on clinical experience the dropout rate will be determined at 10%. That 
impliezs a total sample size of 81 patients. 

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6. Statistical analysis 
Descriptive Statistics 
Statistical analysis will be performed using SPSS. Variables for the description 
of the population are the distribution of age, gender and weight. For describing 
numerical data of age and weight will be used, dependent on the distribution, 
means and standard deviations or median and minimum-maximum values.  
Surgery related variables for further descriptive statistics are cardiopulmonary 
bypass time, aortic cross clamp time and complexity level of aristotle score. 
Cardiopulmonary bypass and aortic cross clamp time will be described by either 
mean or median depending on the distribution. 
Postoperative data variables for descriptive analysis are length of ICU stay (in 
days), intubation time (in hours). Length of ICU stay and intubation time will be 
shown by either mean or median depending on the distribution.  
Descriptive statistics of copeptin values consist of mean values and standard 
deviations of the logarithmized collected data. Three Scattergrams of the 
logarithmized data will be displayed of the first and second measurement, first 
and third measurement and second and third measurement. 
Relevant descriptive data will be graphically shown in an appropriate manner. 
 
Table of descriptive variables 
Variables 
Units 
Variable type 
Age 
in years 
metric 
Gender 
girl/boy 
nominal 
Weight 
in kg 
metric  
CPB Time 
in minutes 
metric 
AoXC Time 
in minutes 
metric 
Complexity level  
1-4 
ordinal 
LOS- ICU 
in days 
metric 
Intubation Time 
in hours 
metric 
Copeptin 
in ng/ml 
metric 
 
 

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Analytical statistics of copeptin values 
Since three samples at different times will be taken of one patient, we are going 
to compare paired means. To compare the copeptin levels of the first and the 
second measurements, will be used paired t-test with a 0,05 two-sided 
significance level. Analyses will be performed using SPSS.  
The null hypothesis implies that the means of the first and the second 
measurements are not significantly different. The alternative hypothesis implies 
that the difference of both means is significant. As copeptin is not expected to 
be normally distributed, logarithmic e-transformations will be performed.  
This test will be repeated for the second and the third measurements and for 
the first and the third measurements.  
 
Correlations 
Secondary outcome endpoints are correlations between copeptin concentration 
and complexity of the procedure (based on the aristotle basic score), clinical 
status (based on length of ICU stay and intubation time) and the perfusion times 
of the heart-lung machine.  
Pearson´s correlations coefficient will be used for calculating the correlation of 
copeptin concentrations with intubation time (in hours), length of ICU stay (in 
days), the aristotle basic score of each procedure and the times of the heart-
lung machine. Data of each correlation will be shown in a scattergram. 
 
7. Ethical aspects 
We tried scheduling this study without any disadvantages or discomfort for the 
subjects. Vascular access for the blood samples will be placed by the 
anethesiologists for every patient undergoing cardiac surgery. 
Also the amount of blood needed for copeptin measurement will be calculated 
as low as possible.  
Prior to inclusion in the study parents will be asked for written informed consent. 
Parents or participants can decide to withdraw from the study at any time and 
can also be removed from the trial by the investigator if exclusion criteria are 
met. No side effects are expected from taking this amount of blood samples. 

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The study will be performed in accordance with the Declaration of Helsinki 
(1964), including all current revisions, and the guidelines for Good Scientific 
Practice required by the Medical Universtiy of Vienna. 
First application for approval of this study and all other procedures involved by 
the Ethics Commitee of the Medical University of Vienna will be made in 
January 2017. 
 
8. Data handling and record keeping 
All patients will be coded with an ongoing number (pseudonymized). The data 
will be collected with protocol sheets and then computerized coded in an SPSS 
file for analysis. The access for the computer will be restricted to members of 
the study.  Only authorized individuals will have access to the original data. 
 
9. Time schedule 
 
 
 
Sept. 
2016 
Nov. 
2016 
Dec. 
2016 
Feb.201
7 
May- 
Nov. 
2017 
Dec. 
2017 
Jan.- 
March 
2018 
Literature research 
 
 
 
 
 
 
 
Sample size calculation  
 
 
 
 
 
 
Project schedule 
 
 
 
 
 
 
 
Ethics application 
 
 
 
 
 
 
 
Data collection 
 
 
 
 
 
 
 
Data analysis 
 
 
 
 
 
 
 
Writing thesis 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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10. Additional contributers 
 
Mag. Dr. Helmuth Haslacher, Medizinische Universität Wien,  
Klinisches Institut für Labormedizin, Währinger Gürtel 18-20, 1090 Wien 
Mail: POST_AKH_KIMCL_BB@akhwien.at 
Tel: 01-40400-53550 
Web: www.meduniwien.ac.at/biobank 
 
Assoc. Prof. Univ. Doz. Dr. Rodrig Marculescu, Medizinische Universität Wien, 
Klinische Abteilung für Medizinisch-chemische Labordiagnostik,  
Klinisches Institut für Labormedizin 
Mail: rodrig.marculescu@meduniwien.ac.at 
 
 
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