LISBON – Although microcirculation in cardiac surgery patients is impaired during the first few hours in the ICU, the degree of impairment was not great enough to affect the accuracy of continuous glucose monitors in a prospective, observational study of 60 patients.
Hyperglycemia, hypoglycemia, and glucose hypervariability are associated with increased mortality in critically ill patients after cardiac surgery. The accuracy of continuous glucose monitoring (CGM) in critically ill patients has been uncertain, said Dr. J. Hans DeVries, an endocrinologist at the University of Amsterdam.
“These results support CGM use in cardiac surgery patients, with quite good sensor accuracy in patients with a low severity of illness,” he said at the meeting.
The patients had a mean age of 65 years; 48 of the 60 were male. Nearly a third (27%) had diabetes. Thirty-two (53%) of the patients had only coronary artery bypass surgery, 16 (27%) had only valve surgery, and 12 (20%) had both procedures. Their APACHE score predicting mortality was low, 0.01. Total ICU stay was 23 hours. Hemodynamic parameters were fairly good, with a microcirculatory function index of 2.8 (out of 3.0). The proportion of perfused vessels was high, 0.97. The patients' peripheral temperature was low, 32.8 °C.
The Medtronic Guardian REAL-Time and the Abbott FreeStyle Navigator sensors were placed subcutaneously in the abdominal wall of each patient prior to surgery. The Navigator performed slightly better than did the Guardian. Microcirculation was measured by microvascular flow index, perfused vessel density, and proportion of perfused vessels using sublingual sidestream dark-field imaging; tissue oxygenation was obtained with near-infrared spectroscopy. Tissue oxygenation and perfused vessel density were impaired in the first hours after surgery, but at no point were any microcirculatory parameters significantly associated with sensor accuracy. For the Navigator CGM, lower peripheral temperature and higher APACHE IV scores were significantly associated with decreased sensor accuracy. For the Guardian, lower peripheral temperature was significantly associated with decreased sensor accuracy.
The EASD's European Foundation for the Study of Diabetes funded the study. Dr. DeVries disclosed ties with Dexcom, Abbott, and Medtronic.
The study results showed 'quite good sensor accuracy in patients with a low severity of illness.'
Source DR.