SAN DIEGO—Thrombotic events occur frequently in critically ill patients yet may often go unrecognized, Wendy Lim, M.D., reported during a poster session at the annual meeting of the American Society of Hematology.
“We're doing a poor job in actually recognizing these diseases,” said Dr. Lim, a clinical research scholar in the department of medicine at McMaster University, Hamilton, Ont. “Because a lot of critically ill patients are endotracheally intubated or sedated, they can't complain of pain in their leg if they have a blood clot, or they can't complain of chest pain if they have a heart attack. We're dependent on patients to express symptoms, and in the case of critically ill patients, we don't have that luxury. We're limited in our abilities.”
She and her associates conducted a retrospective chart review of 198 critically ill patients admitted to the medical-surgical intensive care unit at St. Joseph's Hospital in Hamilton, Ont. The patients were part of a prospective cohort study in which twice-daily ultrasound was used to screen for deep vein thrombosis (DVT). Other thrombotic events were diagnosed based on clinical suspicion and confirmed by conventional diagnostic tests.
On admission to the ICU, ultrasound screening revealed DVT in 6 of the 198 patients (3%), but only 3 of the 6 cases (50%) were clinically suspected.
During the ICU stay, 15 patients (7.6%) developed DVT but only 3 of 15 (20%) were clinically suspected.
On admission to the ICU, pulmonary embolism was clinically recognized in 4 patients (2%), while no cases of PE transpired during the ICU stay.
As for arterial events, 4 patients (2%) were admitted with ischemic stroke and 8 (4%) had a stroke in the ICU.
Levels of cardiac troponin I were measured at least once in the first 24 hours of admission in nearly every patient (90%).
On admission to the ICU, 72 patients (36%) had elevated troponin levels and 38 patients (19%) were diagnosed with myocardial infarction. Dr. Lim reported that 29 patients (15%) had elevated troponin levels without typical ischemic ECG changes while 3 patients (1.5%) had elevated troponin levels with a normal ECG.
During the ICU stay, 12 patients (6%) developed elevated troponin levels with associated ischemic ECG changes. Of these patients, only 5 (42%) were diagnosed with MI on admission.
“I think we need to learn a lot more about how to interpret this high frequency of elevated troponin levels in critically ill patients,” Dr. Lim commented. “Are all of these patients actually having injuries that are being missed and not being treated appropriately? What does this represent?”
A prospective study is underway to help answer these questions, she said.