Editing Cardiac output (section)

=== Ultrasound dilution ===
Ultrasound dilution (UD) uses body-temperature normal saline (NS) as an indicator introduced into an extracorporeal loop to create an atrioventricular (AV) circulation with an ultrasound sensor, which is used to measure the dilution then to calculate cardiac output using a proprietary algorithm. A number of other haemodynamic variables, such as total end-diastole volume (TEDV), central blood volume (CBV) and active circulation volume (ACVI) can be calculated using this method.{{citation needed|date=October 2014}}

The UD method was firstly introduced in 1995.<ref>{{cite journal | vauthors = Krivitski NM | title = Theory and validation of access flow measurement by dilution technique during hemodialysis | journal = Kidney International | volume = 48 | issue = 1 | pages = 244–50 | date = July 1995 | pmid = 7564085 | doi = 10.1038/ki.1995.290 | doi-access = free }}</ref> It was extensively used to measure flow and volumes with extracorporeal circuit conditions, such as [[ECMO]]<ref>{{cite journal | vauthors = Tanke RB, van Heijst AF, Klaessens JH, Daniels O, Festen C | title = Measurement of the ductal L-R shunt during extracorporeal membrane oxygenation in the lamb | journal = Journal of Pediatric Surgery | volume = 39 | issue = 1 | pages = 43–47 | date = January 2004 | pmid = 14694369 | doi = 10.1016/j.jpedsurg.2003.09.017 }}</ref><ref>{{cite journal | vauthors = Casas F, Reeves A, Dudzinski D, Weber S, Lorenz M, Akiyama M, Kamohara K, Kopcak M, Ootaki Y, Zahr F, Sinkewich M, Foster R, Fukamachi K, Smith WA | title = Performance and reliability of the CPB/ECMO Initiative Forward Lines Casualty Management System | journal = ASAIO Journal | volume = 51 | issue = 6 | pages = 681–85 | year = 2005 | pmid = 16340350 | doi = 10.1097/01.mat.0000182472.63808.b9 | s2cid = 1897392 | doi-access = free }}</ref> and [[Hemodialysis|Haemodialysis]],<ref>{{cite journal | vauthors = Tessitore N, Bedogna V, Poli A, Mantovani W, Lipari G, Baggio E, Mansueto G, Lupo A | title = Adding access blood flow surveillance to clinical monitoring reduces thrombosis rates and costs, and improves fistula patency in the short term: a controlled cohort study | journal = Nephrology, Dialysis, Transplantation | volume = 23 | issue = 11 | pages = 3578–84 | date = November 2008 | pmid = 18511608 | doi = 10.1093/ndt/gfn275 | doi-access =  }}</ref><ref>{{cite journal | vauthors = van Loon M, van der Mark W, Beukers N, de Bruin C, Blankestijn PJ, Huisman RM, Zijlstra JJ, van der Sande FM, Tordoir JH | title = Implementation of a vascular access quality programme improves vascular access care | journal = Nephrology, Dialysis, Transplantation | volume = 22 | issue = 6 | pages = 1628–32 | date = June 2007 | pmid = 17400567 | doi = 10.1093/ndt/gfm076 | doi-access = free }}</ref> leading more than 150 peer reviewed publications. UD has now been adapted to [[intensive care unit]]s (ICU) as the COstatus device.<ref>([https://www.transonic.com/products/critical-care/product/costatus/ COstatus] {{webarchive|url=https://web.archive.org/web/20150512224027/https://www.transonic.com/products/critical-care/product/costatus/ |date=12 May 2015 }}, [https://www.transonic.com/ Transonic System Inc.] {{webarchive|url=https://web.archive.org/web/20081029072511/https://transonic.com/ |date=29 October 2008 }} Ithaca, NY){{psc|date = October 2014}}
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The UD method is based on ultrasound indicator dilution.<ref>{{cite journal | vauthors = Krivitski NM, Kislukhin VV, Thuramalla NV | title = Theory and in vitro validation of a new extracorporeal arteriovenous loop approach for hemodynamic assessment in pediatric and neonatal intensive care unit patients | journal = Pediatric Critical Care Medicine | volume = 9 | issue = 4 | pages = 423–28 | date = July 2008 | pmid = 18496416 | pmc = 2574659 | doi = 10.1097/01.PCC.0b013e31816c71bc }}</ref> Blood ultrasound velocity (1560–1585&nbsp;m/s) is a function of total blood protein concentration—sums of proteins in plasma and in red blood red cells—and temperature. Injection of body-temperature normal saline (ultrasound velocity of saline is 1533&nbsp;m/s) into a unique AV loop decreases blood ultrasound velocity, and produces dilution curves.{{citation needed|date=October 2014}}

UD requires the establishment of an extracorporeal circulation through its unique AV loop with two pre-existing arterial and central venous lines in ICU patients. When the saline indicator is injected into the AV loop, it is detected by the venous clamp-on sensor on the loop before it enters the patient's heart's right atrium. After the indicator traverses the heart and lung, the concentration curve in the arterial line is recorded and displayed on the COstatus HCM101 Monitor. Cardiac output is calculated from the area of the concentration curve using the Stewart-Hamilton equation. UD is a non-invasive procedure, requiring only a connection to the AV loop and two lines from a patient. UD has been specialised for application in pediatric ICU patients and has been demonstrated to be relatively safe although invasive and reproducible.{{citation needed|date=October 2014}}