Critical Care Docs Use Strength Test to Predict Outcomes

A new study shows that using a quick and simple bedside handgrip test may assist in diagnosing a known complication of critical illness often associated with an increased risk of death.

Critical care researchers used handgrip tests to test the strength of critically ill patients admitted to the intensive care units of five academic medical centers, including The Ohio State University Medical Center. These patients were on a ventilator for at least five days and had no evidence of pre-existing neuromuscular disease.

Researchers found that handgrip strength was lower in patients with intensive care unit acquired weakness and those patients had good test performance for diagnosis. These same patients also had longer hospital stays and required a ventilator for a longer period of time.

The findings were published in the August issue of the American Journal of Respiratory and Critical Care Medicine.

Intensive care unit acquired weakness, or ICU-acquired weakness, is independently associated with greater morbidity and increased hospital mortality, according to Dr. Naeem Ali, a pulmonologist and critical care specialist at Ohio State’s Medical Center and principal investigator of the study.

“Handgrip strength is also independently associated with poor hospital outcomes and may serve as a simple test that can readily identify weakness,” Ali says.

The development of generalized weakness related to critical illness is common in patients and ICU-acquired weakness is more common in survivors of critical illness, as is a prolonged time on the ventilator resulting in a longer hospital stay. Recovery from this disorder may take months or years. According to Ali, sub-clinical weakness may also contribute to the physical limitations commonly found in survivors.

“Previous strength studies have not definitively demonstrated an independent association with mortality. It is unclear if patients in these studies ever manifested weakness because many may have died before awakening,” Ali said. “There are many factors that could influence outcome such as age, whether or not a patient is hyperglycemic and if a patient experiences multiple organ failure.”

Of the 174 patients involved in the study, 136 were examined for strength upon awakening. The other 38 patients were deemed continuously ineligible from enrollment to death or hospital discharge, and had higher mortality. One-hundred and twenty-three patients who were diagnosed with ICU-acquired weakness had significantly low handgrip strength test results.

“Not only does a handgrip strength test help us identify those patients who are at an increased risk of death, it can also be used as a tool to also identify patients who are at higher risk for poor outcomes and candidates for interventions,” says Ali.

“Additional research is necessary to determine the appropriate threshold of handgrip strength at which critically ill patients are at an increased risk of death. Early identification of these patients with possible ICU-acquired weakness might allow for more expeditious treatments that could reduce the morbidity and mortality of this disease,” adds Ali.

Researchers at the University of Manitoba, MetroHealth Medical Center, Indiana University Medical Center, the University of Cincinnati and Case Western Reserve University participated in the study.

Along with Ali, other Ohio State researchers involved in the study were James O’Brien, Stephen Hoffmann, Gary Phillips, Stanley Lemeshow and Clay Marsh.

(Source: American Journal of Respiratory and Critical Care Medicine: Ohio State University Medical Centre: August 2008)