• Katie Jaschke, Dianna Brown, Alicia Clark, Sarah Doull, Ashley English, Nicole Hoover, Philip Jones, David Klamm, Chung Odom, Brenna Primrose, Kristin Sollars, and Marci Ebberts.
• Katie Jaschke, Dianna Brown, Alicia Clark, Sarah Doull, Nicole Hoover, and David Klamm are staff nurses in the cardiac intensive care unit at Saint Luke's Hospital of Kansas City, Kansas City, Missouri. Ashley English, Chung Odom, Brenna Primrose, and Kristin Sollars were staff nurses in the cardiac intensive care unit at Saint Luke's Hospital of Kansas City when the study was done. English is now a nurse practitioner for the Saint Luke's internal medicine group in Kansas City, Missouri. Odom is now a staff nurse in the surgical trauma intensive care unit at University of Arkansas Medical Center in Little Rock. Primrose is now an acute care nurse practitioner in the neurosurgical intensive care unit at Saint Luke's Hospital. Sollars is now a clinical education specialist in critical care for Saint Luke's Health System, Kansas City, Missouri. Philip Jones is a senior biostatistician for the cardiovascular outcomes group, Mid-America Heart Institute, Kansas City, Missouri. Marci Ebberts is a clinical education specialist for Saint Luke's Health System.
• Am. J. Crit. Care. 2014 Nov 1;23(6):486-93.

BackgroundMeasurement of mixed venous oxygen saturation helps determine whether cardiac output and oxygen delivery are sufficient for metabolic needs. As recommended by the American Association of Critical-Care Nurses guideline, blood samples for determining mixed venous oxygen saturation are obtained by slowly, in 1 to 2 minutes, withdrawing 1.5 mL of blood from the distal port of the pulmonary artery catheter. In theory, the negative force of rapid withdrawal could pull oxygenated blood from the pulmonary capillary bed, causing falsely elevated saturation values.ObjectiveTo determine if the speed of withdrawal affects oxygen content in blood samples used to measure mixed venous oxygen saturation.MethodsThe sample consisted of heart failure patients with pulmonary artery catheters admitted to a cardiac intensive care unit. A prospective, randomized, 2 × 2 crossover design was used to compare mixed venous oxygen saturation in blood samples obtained quickly or slowly. A total of 50 sets of saturation values were analyzed. Each set included 1 blood sample obtained slowly, in 1 to 2 minutes, and 1 obtained rapidly, in 5 seconds.ResultsThe mean difference in saturation values between the fast and the slow groups was -0.3 (CI, -1.5 to 0.8; P = .55), indicating that no meaningful systematic bias is attributable to fast withdrawal of blood.ConclusionsRapid blood sampling does not falsely elevate measurements of mixed venous oxygen saturation.©2014 American Association of Critical-Care Nurses.

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