Interchangeability Between Pleth Variability Index and Internal Jugular Vein Variability Index During Laparoscopic Living Donor Nephrectomy: A Prospective Observational Concordance Study

Objective: This study aimed to evaluate whether PVi and IJV-VI demonstrate sufficient agreement and trending ability to support their clinical interchangeability during laparoscopic living donor nephrectomy. Methods: A prospective observational concordance study was conducted in adult patients undergoing elective laparoscopic living donor nephrectomy under mechanical ventilation. Simultaneous paired measurements of PVi and IJV-VI were obtained every 15 minutes during surgery. Agreement between methods was assessed using repeated-measures Bland Altman analysis. Trending ability was evaluated using polar plot and four-quadrant plot analyses. Results: Thirty-six patients were included, providing 366 paired intraoperative measurements. Bland Altman analysis demonstrated a small overall bias of 0.06% (95%CI;0.21 to 0.39), with wide 95% limits of agreement ranging from -5.10% to 5.22% and a global percentage error of 55.96% (95%CI 37.81-74.17). Polar plot analysis showed poor trending ability, with an angular bias of 14.2o, angular dispersion of 117o, and only 34.5% of vectors within the clinically acceptable +/-30o zone. Four-quadrant analysis demonstrated an overall concordance rate of 84.7% after applying a central exclusion zone. Conclusion: Although PVi and IJV-VI demonstrated a strong positive association during laparoscopic living donor nephrectomy, agreement and trending ability between methods were limited.