Patient and Perioperative Factors Influencing Blood Loss in Endoscopic Transsphenoidal Resection of Pituitary Tumors

Introduction: Given the proximity to vital structures, visualization during endoscopic endonasal transsphenoidal pituitary surgery is vital. Excessive blood loss during this procedure can obscure visualization and place the patient at increased risk for iatrogenic injury. Prior studies of patients undergoing functional endoscopic sinus surgery (FESS) have shown correlations between the type of general anesthetic used and intraoperative blood loss. To our knowledge, no similar study has been done in endoscopic pituitary surgery. Furthermore, the role that tumor type and revision surgery play on intraoperative blood loss and other factors has not been well described.

Objective: To provide a quantitative analysis of these factors in an attempt define the role anesthetic choice plays in endoscopic pituitary surgery. Furthermore, we wish to describe how revision endoscopic pituitary surgery and tumor type may impact blood loss and other perioperative factors.

Methods: An IRB-approved retrospective review was completed for all patients undergoing endoscopic pituitary resection at the University of Michigan from 2010 to 2012. All surgeries were performed in a two-team approach by a single neurosurgeon and single otolaryngologist. Outcomes based on estimated blood loss, length of surgery, length of hospitalization, anesthetic type, revision status, and imaging characteristics related to the surgeries were reviewed. Sensitivity analyses were also performed.

Results: Sixty-five patients who underwent expanded endonasal transsphenoidal resection of pituitary tumors were evaluated. Twenty-five patients had total intravenous anesthesia (TIVA) and 40 patients had combination inhaled and IV anesthesia. Thirty patients had growth hormone-secreting pituitary macroadenomas, of which 15 involved a primary resection and 14 a revision resection. Thirty-five patients had macroadenomas of other pathologic type, of which 26 involved a primary resection and 9 a revision resection. Growth hormone-secreting tumors represented 35% of primary operations and 61% of revision cases. Patients were well matched with regards to age and sex. In subgroup analyses, no differences were seen in preoperative hematocrit, postoperative hematocrit, length of surgery, or length of hospitalization among the various groups.

Differences were seen in blood loss when comparing patients receiving TIVA versus inhaled combination anesthesia (267 mL vs. 382 mL, P = 0.09), non-acromegalic verus acromegalic patients (277 mL vs. 383 mL, P = 0.14), and revision cases versus primary cases (237 mL vs. 373 mL, P = 0.015). Furthermore, although not significant, differences were seen in subgroup analysis comparing: (1) primary resection in non-acromegalic patients versus acromegalic patients (301 mL vs. 488 mL, P = 0.058), (2) primary resection in patients receiving TIVA versus combination inhaled anesthesia (292 mL vs. 420 mL, P = 0.197), (3) revision resection in non-acromegalic versus acromegalic patients (208 mL vs. 255 mL, P = 0.34), and (4) revision resection in patients receiving TIVA versus combination inhaled anesthesia (188 mL vs. 254 mL, P = 0.53).

Conclusions: Intraoperative blood loss during endoscopic transsphenoidal resection of pituitary masses appears to be influenced by a variety of factors. Although only primary surgical resection reaches statistical significance, the presence of growth hormone-secreting tumors and the use of an inhaled anesthetic appear to correlate with an increase in intraoperative blood loss during these surgeries.