Elsevier

Endocrine Practice

Volume 23, Issue 1, January 2017, Pages 46-55
Endocrine Practice

Original Articles
Evaluation of Outcomes and Complications in Patients Who Experience Hypoglycemia After Cardiac Surgery

https://doi.org/10.4158/EP161427.ORGet rights and content

ABSTRACT

Objective: The objective of the study was to elucidate 30-day and long-term outcomes in patients experiencing postoperative hypoglycemia.

Methods: We conducted a retrospective review of patients who underwent cardiac surgery between September 4, 2007, and April 30, 2011, at Northwestern Memorial Hospital who had intensive treatment of hyperglycemia postoperatively. Of 1,325 patients, 215 experienced a hypoglycemic episode (blood glucose <70 mg/dL) within the first 3 postoperative days. A total of 198 were propensity-score (PS) matched to 363 patients without hypoglycemia. The analysis consisted of a comparison of 30-day cardiac outcomes and long-term mortality between those who experienced a hypoglycemic event and those who did not.

Results: Between patients who experienced hypoglycemia compared to those that did not, there were no significant differences in mean glucose values while on insulin drips (119.8 ± 33.5 mg/dL vs. 120.9 ± 30.5 mg/dL; P = .69) or subcutaneous insulin (122.0 ± 38.0 mg/dL vs. 127.2 ± 35.5 mg/dL; P = .11) or postoperative surgical complication rates (30-day mortality: 3.5% vs. 1.7%; complications (any): 40% vs. 42%; 30-day re-admissions: 13% vs. 13%; all cardiac complications: 35% vs. 31%; and all infections: 8% vs. 5%). Over an average of 5.1 ± 2.2 years following index surgery, there was higher all-cause mortality among those PS-matched who had experienced hypoglycemia compared to those who had not (log-rank P = .031), primarily due to those (n = 32) experiencing more than one episode of hypoglycemia.

Conclusion: Postoperative hypoglycemia did not negatively impact immediate surgical complication rates but was associated with a significant risk of increased postoperative morbidity and long-term all-cause mortality in patients experiencing multiple episodes of hypoglycemia.

Abbreviations: BG = blood glucose; BMI = body mass index; CARD = Cardiovascular Research Database; HR = hazard rate; PS = propensity score

Section snippets

INTRODUCTION

Both hyper- and hypoglycemia are common in hospitalized patients. Studies have identified hyperglycemia as an independent risk factor for poor clinical outcomes regardless of diabetes status (1., 2., 3., 4., 5., 6., 7., 8., 9.). Inconsistent benefits and worsening of hypoglycemia risk with intensive glycemic control prompted a shift of recommendations from the American Association of Clinical Endocrinologists and the American Diabetes Association in 2009 to higher glucose targets for inpatients

Study Design

A retrospective electronic medical record (EMR) review of patients who underwent cardiac surgery that involved coronary artery bypass grafting (CABG) and/or cardiac valve repair/replacement and had postoperative insulin management by the Northwestern Glucose Management Service (GMS) between September 4, 2007, and April 30, 2011, at Northwestern Memorial Hospital (NMH) was performed with approval by the Northwestern University Institutional Review Board (IRB), as previously reported (12).

RESULTS

The demographic characteristics of the original groups are shown in Table 1, comparing patients with hypoglycemia (n = 215) and those without hypoglycemia (n = 1,110). Patients experiencing hypoglycemia were more likely to be less overweight, female, have pre-existing diabetes, and have a prior history of cerebrovascular disease, with a trend towards greater decrease in renal function.

When comparing 30-day outcomes between those with hypoglycemia and those without hypoglycemia in the original

DISCUSSION

Hyperglycemia is an independent risk factor for poor clinical outcomes, particularly in hospitalized patients (1., 2., 3., 4., 5., 6., 7., 8., 9.). The role of hypoglycemia in patient outcomes and mortality has come to light in the wake of studies in which strict glycemic control was implemented. In our study, we found no increase in adverse outcomes within the first 30 days following surgery related to all patients experiencing hypoglycemia. However, when patients were subdivided into those

CONCLUSION

In conclusion, hypoglycemia from intensive postoperative glycemic management is common. While there do not appear to be increased adverse outcomes from surgery in the first 30 days postoperatively with single episodes of hypoglycemia, there are increased adverse outcomes and there may be a significant risk of increased long-term mortality in patients who experience more than one episode of hypoglycemia in the first 3 postoperative days. Thus, a single episode of hypoglycemia is common and

ACKNOWLEDGMENT

We thank the many nurses and physicians who participated in the care of these patients.

The results of this study have been presented, in part, previously (Lowden E, Schmidt K, Mulla I, et al. Evaluation of postoperative hypoglycemia in cardiac surgery patients: comparison of outcomes and complications. Presented at: 98th Annual Meeting of The Endocrine Society; April, 2016; Boston, MA. Abstract #694).

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    DISCLOSURE

    The authors have no multiplicity of interest to disclose.

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