Monitoring heparin anticoagulation in major vascular surgery

ISRCTN ISRCTN87607734
DOI https://doi.org/10.1186/ISRCTN87607734
Secondary identifying numbers NHS REC 15/LO/1750
Submission date
21/09/2015
Registration date
25/09/2015
Last edited
12/05/2016
Recruitment status
No longer recruiting
Overall study status
Completed
Condition category
Surgery
Prospectively registered
Protocol
Statistical analysis plan
Results
Individual participant data
Record updated in last year

Plain English summary of protocol

Background and study aims
Vascular surgery is a type of surgery that treats diseases of the arteries and veins. During vascular surgery the drug heparin is commonly used to stop the blood from clotting (heparin anticoagulation). If too much heparin is given the patient is at risk of excess bleeding, and if too little heparin is given the patient is at risk of blood clots during the operation. It is increasingly being seen as best practice to use methods that keep blood loss to a minimum and reduce the requirement for blood transfusion. There is a debate about the best method of monitoring heparin anticoagulation. The most commonly used test to guide heparin dosing during surgery is activated clotting time (ACT), which measures how long it takes your blood to clot. However, there are concerns about variations in response between patients, and how ACT levels relate to laboratory tests of heparin activity. The aims of this study are to compare ACT levels and laboratory tests in patients undergoing major vascular surgery, record the variation in responses to heparin in these patients, and relate heparin activity to patient outcomes such as bleeding and clotting.

Who can participate?
Adult patients undergoing elective major complex vascular surgery with heparin anticoagulation and monitoring.

What does this study involve?
All patients undergoing this type of major vascular surgery are fitted with an arterial line - a thin catheter inserted into an artery from which blood is routinely sampled at intervals throughout the surgery without having to pierce the skin repeatedly. During the study the doctor takes an extra sample of blood (equivalent to half a teaspoonful) each time blood is monitored for heparin anticoagulation. This additional blood is sent to the laboratory to undergo different tests that also monitor heparin activity. Apart from the additional blood sampling during their surgery their care is exactly the same as if they were not in the study. The patients are also followed up to assess whether they have any bleeding or blood clotting, which is part of their routine care.

What are the possible benefits and risks of participating?
There is no direct benefit from taking part in the study, but the results of this study may help future patients and contribute to improved treatment during surgery. The disadvantages to taking part in the study are that the participant will have extra blood tests during surgery. There is no other change in the participant's treatment.

Where is the study run from?
Royal Free London NHS Foundation Trust (UK).

When is the study starting and how long is it expected to run for?
October 2015 to April 2017.

Who is funding the study?
Vascular Anaesthesia Society of Great Britain and Ireland (VASGBI).

Who is the main contact?
Dr Nick Schofield

Contact information

Dr Nick Schofield
Scientific

Royal Free London NHS Foundation Trust
Pond Street
London
NW3 2QG
United Kingdom

ORCiD logoORCID ID 0000-0003-3098-455X

Study information

Study designObservational cohort study
Primary study designObservational
Secondary study designCohort study
Study setting(s)Hospital
Study typeDiagnostic
Scientific titleMonitoring heparin anticoagulation in major vascular surgery: an observational cohort study
Study objectivesAim to correlate activated clotting time (ACT), anti-Xa levels and antithrombin levels during major vascular surgery.
Ethics approval(s)Research & Development Department Royal Free Hospital, 27/10/2015, REC Ref: 15/NI/0219
Health condition(s) or problem(s) studiedHaematology and vascular surgery
InterventionEnrolled patients will have additional blood tests during their surgery - withdrawal of additional 2.7 ml of blood with each monitoring episode. Up to an additional 16 ml of blood may be sampled during the course of surgery. This is equivalent to roughly 1 tablespoon and should not convey any additional risks or adverse consequences. Sampling episodes will be kept to a minimum and minimum volumes of blood withdrawn to reduce any avoidable wastage of blood. Blood will be taken from established invasive lines (arterial line), at the same time point as routine samples and therefore additional needling of the skin will not be necessary. Blood samples will be used to measure the activated clotting time (ACT), thrombin generation and anti-Xa levels.
Intervention typeOther
Primary outcome measureCorrelate ACT and anti-Xa levels during aortic surgery - measured at baseline and up to six time points during surgery
Secondary outcome measures1. Blood loss and bleeding will be measured during theatre
2. Clotting complications will be monitored during theatre and first week postoperatively
Overall study start date05/10/2015
Completion date05/04/2017

Eligibility

Participant type(s)Patient
Age groupAdult
SexBoth
Target number of participants40
Key inclusion criteriaAll adult patients able to give informed consent and undergoing elective major complex vascular surgery in which heparin anticoagulation and monitoring is indicated
Key exclusion criteria1. <18 years old
2. Unable to consent
3. History of heparin allergy
4. Already taking part in research study
Date of first enrolment05/11/2015
Date of final enrolment05/11/2016

Locations

Countries of recruitment

  • England
  • United Kingdom

Study participating centre

Royal Free London NHS Foundation Trust
Pond Street
Hampstead
London
NW3 2QG
United Kingdom

Sponsor information

Royal Free London NHS Foundation Trust (UK)
Hospital/treatment centre

Pond Street
Hampstead
London
NW3 2QG
England
United Kingdom

ROR logo "ROR" https://ror.org/04rtdp853

Funders

Funder type

Other

Vascular Anaesthesia Society of Great Britain and Ireland (VASGBI) Departmental Project Grant DG01-2015

No information available

Results and Publications

Intention to publish date
Individual participant data (IPD) Intention to shareYes
IPD sharing plan summaryAvailable on request
Publication and dissemination planTo be confirmed at later date
IPD sharing plan

Study outputs

Output type Details Date created Date added Peer reviewed? Patient-facing?
HRA research summary 28/06/2023 No No

Editorial Notes

12/05/2016: Ethics approval information added.