Recent Evidence Challenges Four Inpatient Management Habits

Why did you order that test? Dr. Leonard S. Feldman wants you to turn off the autopilot and consider the evidence from the medical literature on the following four practices:

• Is the best target hematocrit for a cardiac patient 30% (or a hemoglobin level of 10 g/dL)?

• Should nasogastric lavage be routine in patients with suspected GI bleeds?

• Is it helpful to measure the fractional excretion of sodium or fractional excretion of urea nitrogen when evaluating acute kidney injury?

• Are daily chest x-rays a good idea in patients on mechanical ventilation in an ICU or step-down unit?

"Many of us do all of these things regularly on a reflexive basis," said Dr. Feldman, director of the general medicine comprehensive consult service at Johns Hopkins University, Baltimore.

Yet recent studies challenge the value of these approaches:

Transfusions

Three studies influenced the AABB (formerly the American Association of Blood Banks) to publish a clinical practice guideline this year recommending a restrictive strategy when considering blood transfusions in hospitalized patients with preexisting cardiovascular disease. The AABB says not to transfuse if the hemoglobin level is above 7-8 g/dL and to consider transfusing patients who are symptomatic or who have a hemoglobin level of less than 8 g/dL, the AABB says (Ann. Intern. Med. 2012;157:49-58).

One recent study randomized 502 patients undergoing coronary artery bypass grafting (CABG) or valve replacement who were on cardiac bypass support to either a liberal strategy aiming to maintain a hematocrit of at or above 30% from the start of surgery until discharge from the ICU or a restrictive strategy that aimed to keep the hematocrit at or above 24%.

Both groups were able to meet these goals. The two groups did not differ significantly, however, in a composite end point of 30-day all-cause mortality and severe morbidity occurring during hospitalization (JAMA 2011;304:1559-67).

There was a trend toward higher risk of death with the restrictive strategy, with a hazard ratio of 1.28, but the ratio ranged from 0.6 to 2.7, so the risk was not statistically significant. Analysis of a slew of secondary outcomes also found no significant differences between groups.

Another study randomized 2,016 patients aged 50 years or older who either had a history of cardiovascular disease or cardiac risk factors and who had a hemoglobin level below 10 g/dL after surgery for hip fracture. The liberal strategy triggered transfusion in all patients with a hemoglobin below 10 g/dL. The restrictive strategy transfused only if the patient showed symptoms of anemia or at the physician’s discretion in patients with a hemoglobin level less than 8 g/dL.

Patients received a lot more blood under the liberal strategy compared with the restrictive strategy – 1,866 vs. 652 units of blood, respectively – but the groups did not differ significantly in death rates or the ability to walk across a room without human assistance at 30 and 60 days after surgery (N. Engl. J. Med. 2011;365:2453-62). Sixty days after surgery, 35% of patients in each group had died or were unable to walk across a room unaided.

"This is a trial that you should be showing all of your orthopedists," Dr. Feldman said. "When the orthopedist says that we need to give a patient blood so the patient will be able to do better in rehab" after hip surgery, point to the data showing that this isn’t necessarily true, he suggested.

An earlier trial of 838 critically ill patients who had hemoglobin levels below 9 g/dL within 72 hours of admission to the ICU found 30-day mortality rates of 19% in those randomized to a restrictive transfusion strategy and 23% in patients randomized to a liberal transfusion strategy, a difference that was not statistically significant (N. Engl. J. Med. 1999;340:409-17).

The liberal strategy transfused when hemoglobin levels fell below 10 g/dL and maintained the hemoglobin at 10-12 g/dL. The restrictive strategy waited until hemoglobin levels fell below 7 g/dL before transfusing and maintained hemoglobin at 7-9 g/dL.

"So, we have three different studies here that really seem to indicate that for transfusion of those patients who are at highest risk – cardiac patients – it did not seem to make a difference in their outcomes, particularly in mortality, if you were restrictive or liberal" in setting thresholds for transfusion, Dr. Feldman said. "This is not the same, though, for patients who are having an acute coronary syndrome. We don’t have any good data for them," and the AABB doesn’t recommend for or against liberal or restrictive transfusion thresholds, he added.