Is Permissive Hypotension Truly Harmless? Early Biomarker Evidence of Subclinical Kidney Injury in Rhinologic Surgery

This study aims to investigate the effects of permissive hypotension, which is routinely used in rhinologic surgeries such as rhinoplasty, septoplasty, and functional endoscopic sinus surgery (FESS), on renal function. Although permissive hypotension has been widely practiced to improve surgical field visibility and reduce intraoperative blood loss, its specific definition is not standardized in the literature. In most studies, maintaining mean arterial pressure (MAP) within the range of 50-65 mmHg is considered permissive hypotension. MAP values below 60 mmHg have been associated with increased risk of cardiac and renal complications. However, in otherwise healthy patients, such episodes are frequently tolerated without clinically apparent renal dysfunction. The kidneys have a strong compensatory reserve capacity, and early tubular injury may not be detected by conventional renal function tests such as serum creatinine. Therefore, the use of more sensitive biomarkers is necessary to detect potential subclinical injury. In this prospective observational study, serum NGAL and cystatin C levels will be measured from routine preoperative and postoperative (12-24 hours) blood samples obtained from adult patients undergoing rhinologic procedures. A ≥25% increase in these biomarkers from baseline will be considered indicative of subclinical acute kidney injury. Additionally, intraoperative hemodynamic data will be monitored, and the duration of MAP \<60 mmHg and MAP \<65 mmHg will be recorded. At the end of the procedure, surgical field conditions will be evaluated using the Boezaart Surgical Field Score. The relationship between these parameters and biomarker changes will be analyzed. The goal of this study is to determine whether early, clinically silent renal injury may occur during permissive hypotension and to provide insight into its potential implications for future renal function. All interventions and blood samplings are part of routine care, and no additional procedures will be performed for research purposes.

NCT Number	NCT07328620
Lead Sponsor	Gazi University
Conditions	Acute Kidney Injury, Hypotension
Enrollment	35 participants
Start Date	2025-03-01
Primary Completion	2025-05-30 (estimated)
Study Completion	2025-07-30 (estimated)
Updated on ClinicalTrials.gov	2026-06-04