Editing Cardiopulmonary bypass (section)

==Technique==

===Pre-operative planning===
CPB requires significant forethought before surgery. In particular, the cannulation, cooling, and cardio-protective strategies must be coordinated between the [[surgeon]], [[Anesthesiology|anesthesiologist]], [[perfusionist]], and [[Nursing|nursing staff]].<ref name=":0">{{Cite book | vauthors = Mokadam NA |title=Cardiopulmonary bypass : a primer |publisher=[[University of Washington]] |year=2015 |oclc=922073684}}</ref>

==== Cannulation strategy ====
The cannulation strategy varies on several operation-specific and patient-specific details. Nonetheless, a surgeon will place a [[cannula]] in the right atrium, vena cava, or femoral vein to withdraw blood from the body. The cannula used to return oxygenated blood is usually inserted in the ascending aorta, but there is a possibility that it is inserted in the femoral artery, axillary artery, or brachiocephalic artery according to the demand of the surgery.<ref name=":33"/><ref name=":13">{{Cite book |title=Kirklin/Barratt-Boyes cardiac surgery : morphology, diagnostic criteria, natural history, techniques, results, and indications |vauthors=Kouchoukos NT, Kirklin JW |date=2013 |publisher=Elsevier/Saunders |isbn=978-1-4557-4605-7 |edition=4th |location=Philadelphia |oclc=812289395}}</ref> After the cannula is inserted, venous blood is drained from the body by the cannula into a reservoir. This blood is then filtered, cooled, or warmed, and oxygenated before it returns to the body through a mechanical pump.

==== Intra-operative technique ====
A CPB circuit must be primed with fluid and all air expunged from the arterial line/cannula before connection to the patient. The circuit is primed with a [[crystalloids|crystalloid]] solution and sometimes blood products are also added. Prior to cannulation (typically after opening the pericardium when using central cannulation), [[heparin]] or another [[anticoagulant]] is administered until the [[activated clotting time]] is above 480 seconds.<ref name=":1">{{Cite book|title=Kirklin/Barratt-Boyes cardiac surgery : morphology, diagnostic criteria, natural history, techniques, results, and indications|date=2013|publisher=Elsevier/Saunders| vauthors = Kouchoukos NT, Kirklin JW |isbn=978-1-4557-4605-7|edition=4th|location=Philadelphia|oclc=812289395}}</ref>

The arterial cannulation site is inspected for [[calcification]] or other disease. Preoperative imaging or an [[ultrasound]] probe may be used to help identify aortic calcifications that could potentially become dislodged and cause an occlusion or [[stroke]]. Once the cannulation site has been deemed safe, two concentric, diamond-shaped [[Purse string|pursestring]] sutures are placed in the distal ascending aorta. A stab incision with a [[scalpel]] is made within the pursestrings and the arterial cannula is passed through the incision. It is important the cannula is passed perpendicular to the aorta to avoid creating an [[aortic dissection]].<ref name=":1" /> The pursestrings sutures are cinched around the cannula using a tourniquet and secured to the cannula.<ref name=":0" /> At this point, the perfusionist advances the arterial line of the CPB circuit and the surgeon connects the arterial line coming from the patient to the arterial line coming from the CPB machine. Care must be taken to ensure no air is in the circuit when the two are connected, or else the patient could develop an [[air embolism]].<ref name=":2" /><ref name=":1" /> Other sites for arterial cannulation include the [[axillary artery]], [[brachiocephalic artery]], or [[femoral artery]].

Aside from the differences in location, [[Vein|venous]] cannulation is performed similarly to arterial cannulation. Since calcification of the [[Vein|venous system]] is less common, the inspection or use of an ultrasound for calcification at the cannulation sites is unnecessary. Also, because the venous system is under much less pressure than the arterial system, only a single suture is required to hold the cannula in place.<ref name=":1" /> If only a single cannula is to be used (dual-stage cannulation), it is passed through the [[right atrial appendage]], through the tricuspid valve, and into the inferior vena cava.<ref name=":2" /> If two cannula are required (single-stage cannulation), the first one is typically passed through the superior vena cava and the second through the inferior vena cava.<ref name=":2" /> The [[femoral vein]] may also be cannulated in select patients.

If the heart must be stopped for the operation, [[cardioplegia]] cannulas are also required. Antegrade cardioplegia (forward flowing, through the heart's arteries), retrograde cardioplegia (backwards flowing, through the heart's veins), or both types may be used depending on the operation and surgeon preference. For antegrade cardioplegia, a small incision is made in the aorta proximal to the arterial cannulation site (between the heart and arterial cannulation site) and the cannula is placed through this to deliver cardioplegia to the [[coronary arteries]]. For retrograde cardioplegia, an incision is made on the posterior (back) surface of the heart through the [[right ventricle]]. The cannula is placed in this incision, passed through the tricuspid valve, and into the [[coronary sinus]].<ref name=":0" /><ref name=":2" /> The cardioplegia lines are connected to the CPB machine.

At this point, the patient is ready to go on bypass. Blood from the venous cannula(s) enters the CPB machine by gravity where it is oxygenated and cooled (if necessary) before returning to the body through the arterial cannula. Cardioplegia can now be administered to stop the heart, and a cross-clamp is placed across the aorta between the arterial cannula and cardioplegia cannula to prevent the arterial blood from flowing backwards into the heart. Setting appropriate blood pressure targets to maintain the health and function of the organs including the brain and kidney are important considerations.<ref>{{Cite journal |last1=Kotani |first1=Yuki |last2=Kataoka |first2=Yuki |last3=Izawa |first3=Junichi |last4=Fujioka |first4=Shoko |last5=Yoshida |first5=Takuo |last6=Kumasawa |first6=Junji |last7=Kwong |first7=Joey SW |date=2022-11-30 |editor-last=Cochrane Heart Group |title=High versus low blood pressure targets for cardiac surgery while on cardiopulmonary bypass |journal=Cochrane Database of Systematic Reviews |language=en |volume=2022 |issue=11 |pages=CD013494 |doi=10.1002/14651858.CD013494.pub2 |pmc=9709767 |pmid=36448514}}</ref>

Once the patient is ready to come off of bypass support, the cross-clamp and cannulas are removed and [[protamine sulfate]] is administered to reverse the anticoagulative effects of heparin.