CardioExchange Archive

Anyone who has been in the hospital, either as a patient or a healthcare provider, is keenly aware that hospitals perform a lot of tests. It has even been suggested that some of those tests may not be necessary. Now a new study published in the Annals of Thoracic Surgery sheds light on just how excessive some of this testing can be.

Researchers analyzed records from 1,894 patients who had cardiac surgery at the Cleveland Clinic and calculated the frequency and total volume of blood drawn from their subjects. They wrote that they “were astonished by the extent of bloodletting” they discovered.

They reported the patients they studied were subjected to 221,498 laboratory tests, which averaged out to 115 tests per patient. Forty percent of the tests measured arterial or venous blood gas levels, 18% assessed blood coagulation, 14% were for a complete blood count (CBC), and 13% were for metabolic panels.

The cumulative median volume of blood was 454 mL per patient, which “is roughly equivalent to 1 to 2 cans of soda,” said the first author of the paper, Dr. Colleen Koch, who recently left the Cleveland Clinic to become the chair of the department of anesthesiology and critical care medicine at Johns Hopkins. Patients in the highest quartile of volume lost nearly a full liter of blood. The volume of blood drawn was much higher while the patients were in the cardiovascular ICU (332 mL) than when they were on the regular hospital floor (118 mL).

“Bloodletting to such an extent has consequences,” wrote the authors. Hospital-acquired anemia often results in the need for red blood cell transfusions, they note. In an email interview, Dr. Koch noted that higher phlebotomy volume increases the likelihood of hospital-acquired anemia, and patients with hospital-acquired anemia have worse outcomes.

In an invited commentary, Dr. Milo Engoren, an anesthesiologist at the University of Michigan, expressed shock at the finding. His remarks begin with a simple “Wow!” He continues: “we also need to step back and ask, ‘Does this patient need this test?’ Are we getting the test because the answer will change therapy? Or are we getting the test from habit or other inappropriate reason? Avoiding unnecessary blood tests will not only help prevent anemia (and maybe transfusion) but will also save money.”

Commenting on the study, Yale University cardiologist Harlan Krumholz said that the study shows “another facet of how hospitals can be toxic rather than healing. Is there really a need to drain patients of so much blood? Surely, this is an area where we can decrease the harm of being in the hospital.”

Dr. Matthew Sparks, a nephrologist at Duke University, said that this is “a common problem” and “a difficult habit to break.” But, he notes, “the culture needs to be stopped. The cardiovascular ICU however, is a place where things are dynamic and changing quickly. So I am not surprised they draw so many labs. However, when you see the quantified effect it really makes you take a step back and question the harm from so much blood loss.”

Original illustration by Max Husten