Perioperative management
Microcirculation and its relation to continuous subcutaneous glucose sensor accuracy in cardiac surgery patients in the intensive care unit

https://doi.org/10.1016/j.jtcvs.2013.06.017Get rights and content
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Objective

Continuous glucose monitoring could be helpful for glucose regulation in critically ill patients; however, its accuracy is uncertain and might be influenced by microcirculation. We investigated the microcirculation and its relation to the accuracy of 2 continuous glucose monitoring devices in patients after cardiac surgery.

Methods

The present prospective, observational study included 60 patients admitted for cardiac surgery. Two continuous glucose monitoring devices (Guardian Real-Time and FreeStyle Navigator) were placed before surgery. The relative absolute deviation between continuous glucose monitoring and the arterial reference glucose was calculated to assess the accuracy. Microcirculation was measured using the microvascular flow index, perfused vessel density, and proportion of perfused vessels using sublingual sidestream dark-field imaging, and tissue oxygenation using near-infrared spectroscopy. The associations were assessed using a linear mixed-effects model for repeated measures.

Results

The median relative absolute deviation of the Navigator was 11% (interquartile range, 8%-16%) and of the Guardian was 14% (interquartile range, 11%-18%; P = .05). Tissue oxygenation significantly increased during the intensive care unit admission (maximum 91.2% [3.9] after 6 hours) and decreased thereafter, stabilizing after 20 hours. A decrease in perfused vessel density accompanied the increase in tissue oxygenation. Microcirculatory variables were not associated with sensor accuracy. A lower peripheral temperature (Navigator, b = −0.008, P = .003; Guardian, b = −0.006, P = .048), and for the Navigator, also a higher Acute Physiology and Chronic Health Evaluation IV predicted mortality (b = 0.017, P < .001) and age (b = 0.002, P = .037) were associated with decreased sensor accuracy.

Conclusions

The results of the present study have shown acceptable accuracy for both sensors in patients after cardiac surgery. The microcirculation was impaired to a limited extent compared with that in patients with sepsis and healthy controls. This impairment was not related to sensor accuracy but the peripheral temperature for both sensors and patient age and Acute Physiology and Chronic Health Evaluation IV predicted mortality for the Navigator were.

CTSNet classification

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Abbreviations and Acronyms

APACHE IV PM
Acute Physiology and Chronic Health Evaluation IV predicted mortality
CGM
continuous glucose monitoring
HI
heterogeneity index
ICU
intensive care unit
IQR
interquartile range
MFI
microvascular flow index
PVD
perfused vessel density
PPV
proportion of perfused vessels
RAD
relative absolute deviation
SDF
sidestream dark-field
StO2
tissue oxygenation

Cited by (0)

This study was supported by a European Foundation for the Study of Diabetes/LifeScan research grant.

Disclosures: J. H. DeVries or institutions to which he is connected received research support and fees from speaking engagements from Abbott Diabetes Care and Medtronic and is on an advisory board of Abbott Diabetes Care. The other authors have nothing to disclose with regard to commercial support.