Introduction:
Surgical resection by either transperitoneal laparoscopic adrenalectomy (TLA) or posterior retroperitoneoscopic adrenalectomy (PRA) is the therapy for pheochromocytomas (PCC). PRA results in faster operating times with less blood loss and faster recovery, but is demanding due to smaller working space with higher CO­2-pressures and may therefore result in more tumor manipulation and blood pressure fluctuations. We aim to investigate the impact of surgical technique on intraoperative hemodynamic instability in patients undergoing PCC surgery using the hemodynamic instability (HI) score.

Methods:
We included patients who underwent endoscopic adrenalectomy for PCC from 2007-2022. Patients who were lacking intraoperative data, after conversion to open adrenalectomy or switch to another endoscopic technique,  with bilateral adrenalectomy and combined surgical procedures, have been excluded. Patients were preoperatively prepared with alpha-adrenoreceptor blockers for 14 days. Intraoperative hemodynamic control was protocolized and similar in all patients. The primary outcome was hemodynamic instability (HI-score) and secondary outcomes were hemodynamic parameters and drug administration and fluid infusion.

Results
Overall, 57 underwent TLA and 44 underwent PRA. The two groups were similar in baseline characteristics. The HI-score was higher in PRA than in TLA patients (97 vs 46). In PRA patients there were more frequent (IQR:2-5 vs IQR:1-3) and longer episodes of hypotension (5.6% vs 7.1%), and longer episodes of bradycardia (9.9% vs 16.9%, p=0.038). On the contrary, TLA patients had higher maximum systolic blood pressure (169mmHg vs 157mmHg), more frequent episodes of tachycardia (31.6% vs 6.8%) and higher maximum heart rate (90bpm vs 80bpm). PRA patients needed more often vasoconstrictive drugs (97.7% vs 78.9%) and fluid infusion (1111ml/h vs 798ml/h), whereas TLA patients received more vasodilating drugs (64.9% vs 38.6%).

Conclusion: 
PRA is associated with higher hemodynamic instability than TLA due to hypotension requiring vasoconstrictive drugs.