Low Albumin Is Not Associated With Microvascular Free Flap Failure

Tuesday, September 11, 2012: 2:00 PM
Jonathan Shum DDS, MD Portland, OR, USA
Etern S. Park DDS, MD Portland, OR, USA
Michael Markiewicz DDS, MPH, MD Portland, OR, USA
R. Bryan Bell DDS, MD Portland, OR, USA
Tuan G. Bui DDS, MD Portland, OR, USA
Bryce Potter DMD, MD Portland, OR, USA
Eric Dierks DMD, MD Portland, OR, USA
Introduction:  Albumin has been defined as a predictive measure for the risk of adverse postoperative outcomes. [i]  The prognostic value is applied to all surgical specialties including the evaluation of patients in the intensive care setting. With respect to microvascular head and neck reconstruction; albumin is also described to have anticoagulant effects and has been used for this property in cardiothoracic surgery as a primer for cardiopulumonary bypass circuits.[ii]  This investigators’ purpose was to answer the following clinical question: “Among patients undergoing microvascular head and neck reconstruction, do free flaps in subjects with low albumin, when compared to those with normal albumin, have a higher failure rate?” The investigators hypothesized that: 1) low albumin was associated with a higher flap failure, and 2) there exist one or more variables associated with flap failure, in those subjects undergoing microvascular free flap reconstruction. The specific aims were: 1) to estimate and compare the odds of free flap failure in subjects with low albumin; and 2) to identify risk factors associated with free flap failure.

Materials and Methods: To address the research purpose, the investigators initiated a retrospective cohort study and enrolled a sample of subjects that underwent head and neck microvascular reconstruction. The primary predictor variable was a binary variable, albumin. Values below 3.5 were considered low. The primary outcome variable was free flap failure. Other covariates measured include age, sex, being underweight or overweight (defined by BMI), having a malignant vs benign tumor, location of the ablative defect, and type of free flap used. To assess the relationship between malnutrition and free flap failure, the investigators developed a multivariate logistic regression model, adjusted for possible confounding variables. Candidate variables for inclusion in the model were those covariates jointly associated with the primary predictor and outcome variables at p < 0.15 in the univariate analyses. Biologically significant variables, i.e. age and sex, were entered into the model.  Level of statistical significance in the adjusted multivariate model was set at an α level of 0.05. 

Results: The sample was composed of 101 subjects that underwent head and neck microvascular reconstruction. There were statistically or near statistically significant differences (p ≤ 0.15) between the two study groups and age. In the univariate analyses, low albumin was not  significantly associated with free flap failure (OR = 2.8, 95% CI: 0.5, 14.6, p= 0.2). In the proposed multivariate model that controlled for age and sex, low albumin again was not associated with an increased risk for flap failure (OR = 2.3, 95% CI: 0.4, 13.2, p = 0. 4).

Conclusion: The results of this study suggest that low albumin in the perioperative period is not associated with microvascular free flap failure in subjects with head and neck tumors.


[i] Daley J, Khuri SF, Henderson W et al.  Risk adjustment of the postoperative morbidity rate for the comparative assesssment of the quality of surgical care: results of the National Veterans Affairs Surgical Risk Study.  J Am Coll Surg 1997: 185(4): 328 – 340.

 

[ii] Margarson MP, Soni N. Serum albumin: touchstone or totem? Anesthesia 1998: 53(8): 789 – 803.

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