A new thromboelastometry analyser (ClotPro, Enicor GmbH, Munich, Germany) with improved technology was developed. This device has an improved new-generation viscoelastometric testing technique and enables the detection and assessment of factor deficiencies, low fibrinogen, platelet contribution (to whole blood coagulation), heparin and direct oral anticoagulants effects, fibrinolysis and antifibrinolytic drugs. This study aims to determine reference ranges for the ClotPro device for all paediatric age groups.

Viscoelastic testing as a relatively novel method to assess coagulation status appears favourable in reducing blood product transfusions. The tests are performed on whole blood instead of plasma, which saves time and gives a quick sight at the interaction between cellular and plasmatic clotting factors.

Reviews of the literature suggest that transfusions of packed red blood cells (pRBC), plasma, and platelets are all decreased in patients whose transfusions were guided by viscoelastic tests rather than by clinical judgement or conventional laboratory tests.

The benefits of viscoelastic coagulation monitoring have been described in many fields of surgery and intensive care. Current literature and a guideline for the treatment of massive haemorrhage in perioperative bleeding and trauma patients recommend the use of viscoelastic tests to guide haemostatic resuscitation.

Inclusion Criteria:

• paediatric patients attending hospital for elective surgery or diagnostic imaging undergoing general anaesthesia are going to be eligible to participate.
• children whose parents agree to participate are provided with oral and written information and written informed consent has to be obtained.

Exclusion Criteria:

• problematic blood collection
• age over 16 years
• emergency surgery
• systemic infection
• known bleeding disorders
• history of congenital or acquired coagulopathy including renal, liver and bone marrow disease,
• any medication interfering with haemostasis
• prophylactic or therapeutic anticoagulant therapy (acetylsalicylic acid within the last 10 days or low-molecular-weight heparins within the last 48 h)
• administration of colloids hydroxyethyl starch (HES)/albumin, or blood products before the blood withdrawal

6 Individual age categories are determined to monitor: ASA physical status I-II

1. 0 (full term) to 3 months
2. 4 to12 months
3. 13 to 24 months
4. 2 to 5 years
5. 6 to10 years
6. 11 to 16 years Demographic data to be recorded: age, gender, weight, height.