This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Francis, D. P. Articles by Coats, A. J. S. Search for Related Content PubMed PubMed Citation Articles by Francis, D. P. Articles by Coats, A. J. S. Related Collections Information technology Pulmonary biology and circulation Coronary circulation

(Circulation. 1999;100:2198.)
© 1999 American Heart Association, Inc.

Basic Science Reports

Oxygenation in Patients With a Functionally Univentricular Circulation and Complete Mixing of Blood

Are Saturation and Flow Interchangeable?

Darrel P. Francis, MA, MRCP; Keith Willson, MSc, MIPEM; Sara A. Thorne, MD, MRCP; L. Ceri Davies, BSc, MRCP; Andrew J. S. Coats, DM, FRCP

From the Department of Cardiology (D.P.F., S.A.T., L.C.D., A.J.S.C.) and the Biomedical Engineering Research Unit (K.W.), Royal Brompton Hospital, and the National Heart and Lung Institute, Imperial College of Science, Technology, and Medicine (D.P.F., S.A.T., L.C.D., A.J.S.C.), London, UK.

Background—Perioperative management of patients with complete mixing of pulmonary and systemic blood centers on approximately equating pulmonary (Qp) and systemic (Qs) blood flow (Qp/Qs1). This empirically derived target is opposed by theoretical studies advocating a target Qp/Qs well below 1. We studied the cause of this persistent discrepancy.

Methods and Results—Classic theoretical studies have concentrated on maximizing 1 of many potential combination parameters of arterial oxygen content (CaO₂) and systemic blood flow: total oxygen delivery (DO₂)=CaO₂xQs. We defined "useful" oxygen delivery as the amount of oxygen above a notional saturation threshold (Sat_Thresh): D(u)O₂=carrying capacityx(SaO₂-Sat_Thresh)xQs. Whereas DO₂ peaks at Qp/Qs ratios <1, D(u)O₂ peaks at higher Qp/Qs ratios, nearer to (or exceeding) 1. Systemic venous saturation (which mirrors tissue oxygen tension) peaks at Qp/Qs=1.

Conclusions—First, the standard model of single-ventricle physiology can be reexpressed in a form allowing analysis by differential calculus, which allows broader conclusions to be drawn than does computer modeling alone. Second, the classic measure DO₂ fails to reflect the fact that proportional changes in saturation and flow are not clinically equivalent. Recognizing this asymmetry by using D(u)O₂ can give a target Qp:Qs balance that better represents clinical experience. Finally, to avoid an arbitrary choice of Sat_Thresh, systemic venous oxygen saturation (SsvO₂) may be a useful parameter to maximize: this occurs at a Qp/Qs ratio of 1. Attempts to increase DO₂ by altering Qp/Qs away from this value will inevitably reduce SsvO₂ and therefore tissue oxygenation. Oxygen delivery is far from synonymous with tissue oxygen status.

Key Words: oxygen • circulation • blood flow

This article has been cited by other articles:

				J. A. DiNardo Phenoxybenzamine Is Indicated in Treatment of Hypoplastic Left Heart Syndrome: Con Anesth. Analg., August 1, 2007; 105(2): 310 - 311. [Full Text] [PDF]

				D. B. McElhinney and D. F. Teitel From Theory to Practice: Optimizing the Efficiency of an Inefficient Circulation Circulation, September 19, 2006; 114(12): 1226 - 1228. [Full Text] [PDF]

				G.-P. Diller, A. Uebing, K. Willson, L. C. Davies, K. Dimopoulos, S. A. Thorne, M. A. Gatzoulis, and D. P. Francis Analytical Identification of Ideal Pulmonary-Systemic Flow Balance in Patients With Bidirectional Cavopulmonary Shunt and Univentricular Circulation: Oxygen Delivery or Tissue Oxygenation? Circulation, September 19, 2006; 114(12): 1243 - 1250. [Abstract] [Full Text] [PDF]

				U Theilen and L Shekerdemian The intensive care of infants with hypoplastic left heart syndrome Arch. Dis. Child. Fetal Neonatal Ed., March 1, 2005; 90(2): F97 - F102. [Abstract] [Full Text] [PDF]

				D. Soetenga and K. A. Mussatto Management of Infants With Hypoplastic Left Heart Syndrome: Integrating Research Into Nursing Practice Crit. Care Nurse, December 1, 2004; 24(6): 46 - 66. [Full Text] [PDF]

				G. M. Hoffman, J. S. Tweddell, N. S. Ghanayem, K. A. Mussatto, E. A. Stuth, R. D. B. Jaquis, and S. Berger Alteration of the critical arteriovenous oxygen saturation relationship by sustained afterload reduction after the norwood procedure J. Thorac. Cardiovasc. Surg., March 1, 2004; 127(3): 738 - 745. [Abstract] [Full Text] [PDF]

				G. M. Hoffman, N. S. Ghanayem, J. M. Kampine, S. Berger, K. A. Mussatto, S. B. Litwin, and J. S. Tweddell Venous saturation and the anaerobic threshold in neonates after the Norwood procedure for hypoplastic left heart syndrome Ann. Thorac. Surg., November 1, 2000; 70(5): 1515 - 1520. [Abstract] [Full Text] [PDF]