Editing Cardiopulmonary bypass (section)

== Contraindications and special considerations ==
There are no absolute contraindications to cardiopulmonary bypass.<ref>{{Citation| vauthors = Ismail A, Miskolczi SY |title=Cardiopulmonary Bypass|date=2019|url=http://www.ncbi.nlm.nih.gov/books/NBK482190/|work=StatPearls|publisher=StatPearls Publishing|pmid=29489210|access-date=2020-01-21 |id=NBK482190 }}</ref> However, there are several factors that need to be considered by the care team when planning an operation.

[[Heparin-induced thrombocytopenia]] and [[heparin-induced thrombocytopenia and thrombosis]] are potentially life-threatening conditions associated with the administration of heparin. In both of these conditions, [[Antibody|antibodies]] against heparin are formed which causes [[Coagulation|platelet activation]] and the formation of [[Thrombus|blood clots]]. Because heparin is typically used in CPB, patients who are known to have the antibodies responsible for heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis require alternative forms of anticoagulation. [[Bivalirudin]] is the most studied heparin-alternative in people with heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis requiring CPB.<ref>{{cite journal | vauthors = Shore-Lesserson L, Baker RA, Ferraris VA, Greilich PE, Fitzgerald D, Roman P, Hammon JW | title = The Society of Thoracic Surgeons, The Society of Cardiovascular Anesthesiologists, and The American Society of ExtraCorporeal Technology: Clinical Practice Guidelines-Anticoagulation During Cardiopulmonary Bypass | journal = The Annals of Thoracic Surgery | volume = 105 | issue = 2 | pages = 650–662 | date = February 2018 | pmid = 29362176 | doi = 10.1016/j.athoracsur.2017.09.061 | doi-access = free }}</ref>

A small percentage of patients, such as those with an [[antithrombin III deficiency]], may exhibit resistance to heparin. In these patients, patients may need additional heparin, fresh frozen plasma, or other blood products such as recombinant anti-thrombin III to achieve adequate anticoagulation.<ref>{{cite journal | vauthors = Finley A, Greenberg C | title = Review article: heparin sensitivity and resistance: management during cardiopulmonary bypass | journal = Anesthesia and Analgesia | volume = 116 | issue = 6 | pages = 1210–22 | date = June 2013 | pmid = 23408671 | doi = 10.1213/ANE.0b013e31827e4e62 | s2cid = 22500786 | doi-access = free }}</ref>

A [[persistent left superior vena cava]] is thoracic system variation in which the left-sided vena cava fails to involute during normal development. It is the most common variation of the thoracic venous system, occurring in approximately 0.3% of the population.<ref>{{cite journal | vauthors = Berg C, Knüppel M, Geipel A, Kohl T, Krapp M, Knöpfle G, Germer U, Hansmann M, Gembruch U | display-authors = 6 | title = Prenatal diagnosis of persistent left superior vena cava and its associated congenital anomalies | journal = Ultrasound in Obstetrics & Gynecology | volume = 27 | issue = 3 | pages = 274–280 | date = March 2006 | pmid = 16456841 | doi = 10.1002/uog.2704 | s2cid = 26364072 | doi-access = free }}</ref> The abnormality is often detected on pre-operative imaging studies, but may also be discovered intra-operatively. A persistent left superior vena cava may make it difficult to achieve proper venous drainage or deliver of retrograde [[cardioplegia]]. Management of a persistent left superior vena cava during CPB depends on factors such as the size and drainage site of the vena cava variation.<ref name=":33">{{Cite book |title=Cardiac surgery in the adult |vauthors=Cohn LH |date=2017-08-28 |publisher=McGraw-Hill Education |isbn=978-0-07-184487-1 |edition=5th |oclc=930496902}}</ref>

Cerebral perfusion, brain blood circulation, always has to be under consideration when using CPB. Due to the nature of CPB and its impact on circulation, the body's own [[cerebral autoregulation]] is affected. The occurrence and attempts of preventing this issue has been addressed many times, but still without complete understanding.<ref>{{cite journal |vauthors=Arthursson H, Kjellberg G, Tovedal T, Lennmyr F |title=Cerebral oxygenation and autoregulation during rewarming on cardiopulmonary bypass |journal=Perfusion |volume=38 |issue=3 |pages=523–9 |date=April 2023 |pmid=35038948 |pmc=10026164 |doi=10.1177/02676591211064961 }}</ref>