The Effect of Body Mass Index on Surgical Blood Loss in Functional Endoscopic Sinus Surgery

Introduction: As functional endoscopic sinus surgery (FESS) has emerged as a standard of care in patients with chronic sinus disease, intraoperative blood loss can often be problematic. Identification of risk factors for operative blood loss during FESS can help in patient care and perioperative planning. The effect of body mass index (BMI) on intraoperative blood loss during FESS has not been established.

Methods: A retrospective review was performed of patients who underwent FESS for chronic sinusitis by a single surgeon over a 5-year period. Patients were then grouped according to their BMI: low/normal weight (<25), overweight (25–29), or obese (>29). Comparative statistical analysis was done between BMI groups using one-way ANOVA for operative time, total blood loss, and rate of blood loss. The strength of the linear association between blood loss and BMI was assessed using Spearman’s rank correlation coefficient.

Results: A total of 321 patients were included. Patients were categorized into three groups: low/normal BMI (n = 97), overweight (n = 84) and obese (n = 120). The average BMI for each category was 22.0, 27.0, and 35.4, respectively. The mean total operative blood loss for groups 1, 2, and 3 were 198.6, 197.7, and 270.1 mL, respectively, with corresponding rates of blood loss of 1.40, 1.31, and 1.79 mL/min. Comparative analysis revealed a statistically significant difference in total blood loss (p = 0.009) and rate of blood loss (p = 0.012) among the three BMI categories. There was no significance when comparing operative time between the three groups (p = 0.61). Significant linear association was found between total blood loss and rate of blood loss with BMI (p = 0.003 and p = 0.004, respectively). A linear correlation between operative time and total blood loss was also seen (p <  0.00001) but not between BMI and operative time (p = 0.273).

Conclusion: Functional endoscopic sinus surgery can be associated with a large amount of blood loss and identification of risk factors related to blood loss can help improve perioperative patient care. This study shows a correlation between operative blood loss and increasing BMI which may help identify those at risk for intraoperative bleeding. Further larger studies are needed to more clearly delineate this association.

Patient demographics and study results:

	BMI <  25	BMI 25–29	BMI > 29
N	97	84	140
Sex (% male)	38 (39.2%)	44 (52.4%)	73 (52.1%)
Chronic rhinosinusitis w/ polyps (%)	17 (17.5%)	16 (19.0%)	32 (22.9%)
Cystic fibrosis (%)	20 (20.6%)	1 (1.2%)	2 (1.4%)
Average BMI (kg/m2)	22.0	27.0	35.4
Average operative time (min)[*]	140.5	145.0	146.5
Average total blood loss (mL)[**]	198.6	197.9	270.1
Average blood loss rate (mL/min)[***]	1.40	1.31	1.79

^* p = 0.61

^** p = 0.009

^*** p = 0.012.