Simultaneous determination of the accuracy and precision of closed-circuit cardiac output rebreathing techniques. J Appl Physiol 103: [867][868][869][870][871][872][873][874] 2007. First published June 7, 2007; doi:10.1152/japplphysiol.01106.2006.-Foreign and soluble gas rebreathing methods are attractive for determining cardiac output (Q c) because they incur less risk than traditional invasive methods such as direct Fick and thermodilution. We compared simultaneously obtained Q c measurements during rest and exercise to assess the accuracy and precision of several rebreathing methods. Q c measurements were obtained during rest (supine and standing) and stationary cycling (submaximal and maximal) in 13 men and 1 woman (age: 24 Ϯ 7 yr; height: 178 Ϯ 5 cm; weight: 78 Ϯ 13 kg; V O2max: 45.1 Ϯ 9.4 ml⅐kg Ϫ1 ⅐min Ϫ1; mean Ϯ SD) using one-N 2O, four-C2H2, one-CO2 (single-step) rebreathing technique, and two criterion methods (direct Fick and thermodilution). CO 2 rebreathing overestimated Q c compared with the criterion methods (supine: 8.1 Ϯ 2.0 vs. 6.4 Ϯ 1.6 and 7.2 Ϯ 1.2 l/min, respectively; maximal exercise: 27.0 Ϯ 6.0 vs. 24.0 Ϯ 3.9 and 23.3 Ϯ 3.8 l/min). C 2H2 and N2O rebreathing techniques tended to underestimate Q c (range: 6.6 -7.3 l/min for supine rest; range: 16.0 -19.1 l/min for maximal exercise). Bartlett's test indicated variance heterogeneity among the methods (P Ͻ 0.05), where CO 2 rebreathing consistently demonstrated larger variance. At rest, most means from the noninvasive techniques were Ϯ10% of direct Fick and thermodilution. During exercise, all methods fell outside the Ϯ10% range, except for CO 2 rebreathing. Thus the CO2 rebreathing method was accurate over a wider range (rest through maximal exercise), but was less precise. We conclude that foreign gas rebreathing can provide reasonable Q c estimates with fewer repeat trials during resting conditions. During exercise, these methods remain precise but tend to underestimate Q c. Single-step CO 2 rebreathing may be successfully employed over a wider range but with more measurements needed to overcome the larger variability.foreign gas rebreathing; physiological gas rebreathing; direct Fick; thermodilution CARDIAC OUTPUT (Q c ), the volume of blood pumped by the heart each minute, can be measured several ways, both invasively and noninvasively. Each technique has advantages and limitations that may restrict its application during exercise. The direct Fick method has been implemented in humans in clinical environments since 1940 (21); together with the thermodilution method, they are considered "gold standard" Q c techniques. These methods, however, are expensive, require medical expertise, and are invasive, limiting their widespread utility (44). For instance, occasional reported complications associated with these gold standards include arrhythmias and pulmonary artery or right ventricle perforation (30, 40).Rebreathing techniques, employing foreign or physiological tracers, are attractive alternatives because their relative risk is considerably...

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Successful organizations have the ability to measure and act on key indicators and events in real time. By leveraging the power of virtual instrumentation and open architecture standards, multidimensional executive dashboards can empower health care organizations to make better and faster data-driven decisions. This article will highlight how user-defined virtual instruments and dashboards can connect to hospital information systems (e.g., admissions/discharge/transfer systems, patient monitoring networks) and use statistical process control to "visualize" information and make timely, data-driven decisions. The case studies described will illustrate enterprisewide solutions for: bed management and census control, operational management, data mining and business intelligence applications, and clinical applications (physiological data acquisition and wound measurement and analysis).

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