Open AccessArticle Blood Pressure and Pleth Variability Index as Predictors of Tourniquet-Release Hypotension in Elderly Patients Undergoing Total Knee Arthroplasty: A Prospective Observational Study Department of Anesthesiology and Pain Medicine, Kyung Hee University College of Medicine, Kyung Hee University Hospital, Seoul 02447, Republic of Korea * Author to whom correspondence should be addressed. Life 2026, 16(6), 973; https://doi.org/10.3390/life16060973 (registering DOI) Submission received: 30 April 2026 / Revised: 1 June 2026 / Accepted: 8 June 2026 / Published: 9 June 2026 Abstract Background: Tourniquet release during total knee arthroplasty (TKA) can cause abrupt hypotension in elderly patients, but simple intraoperative predictors remain unclear. We evaluated whether blood pressure and the pleth variability index (PVi) predict tourniquet-release hypotension. Methods: In this prospective observational study, 90 elderly patients undergoing TKA with a thigh tourniquet were analyzed. Noninvasive blood pressure and PVi were recorded at predefined perioperative time points. The primary endpoint was hypotension after deflation, defined as mean blood pressure < 65 mmHg. Secondary exploratory endpoints were systolic blood pressure < 90 mmHg and a ≥20% decrease in systolic blood pressure from pre-release values. Results: The primary endpoint occurred in 28.9% of patients and was more common in those with lower pre-release blood pressure. In multivariable analysis, pre-release mean blood pressure and PVi measured immediately after intubation independently predicted hypotension, with odds ratios of 0.95 per 1 mmHg increase and 1.12 per 1-point increase, respectively. The combined model showed moderate discrimination (AUC = 0.71). Similar patterns were observed for systolic definitions, without clear associations with early postoperative complications or hospital length of stay. Conclusions: Lower pre-release mean blood pressure and higher intubation PVi may help identify elderly TKA patients at risk of tourniquet-release hypotension. Keywords: blood pressure; hypotension; pleth variability index; elderly patients; total knee arthroplasty; tourniquet 1. Introduction Total knee arthroplasty (TKA) is frequently performed in elderly patients, many of whom have long-standing hypertension, coronary artery disease, and other cardiovascular comorbidities [ 1]. Pneumatic thigh tourniquets are commonly used to reduce blood loss and improve surgical visualization, but tourniquet deflation may cause abrupt hemodynamic changes, including hypotension, acidosis, and hyperkalemia [ 2]. In vulnerable patients, these changes may compromise myocardial and cerebral perfusion [ 3]. Large perioperative cohort studies have shown that even short periods of intraoperative hypotension, particularly when mean blood pressure (MBP) falls below approximately 65 mmHg, are associated with postoperative myocardial injury, acute kidney injury (AKI), stroke, and increased mortality [ 4 Dynamic preload indices such as the pleth variability index (PVi) have attracted attention as noninvasive markers of fluid responsiveness during controlled mechanical ventilation [ 7, 8, 9, 10]. Higher PVi values have been associated with hypovolemia and increased likelihood of fluid responsiveness [ 11], and several studies have shown that elevated baseline PVi predicts hypotension after induction of general anesthesia, particularly in high-risk or geriatric patients [ 6, 12, 13, 14]. However, the clinical utility of PVi in geriatric cohorts remains controversial, as age-related vascular stiffness, baseline vasoplegia, and the frequent administration of vasoactive medications can significantly alter peripheral perfusion waveforms and compromise the reliability of dynamic preload indices [ 15, 16]. Currently, the utility of PVi for predicting hemodynamic instability during specific intraoperative events, such as tourniquet release during TKA, remains unclear. Although pneumatic thigh tourniquets are widely used in TKA, abrupt hemodynamic depression after deflation is highly prevalent and hazardous in geriatric patients due to physiological aging and cardiovascular comorbidities [ 2, 3]. Traditional static hemodynamic monitors are often insufficient for predicting this sudden vasodilation-driven hypotension, and there is a critical clinical gap in simple, noninvasive, and dynamic predictors to stratify patient risk before tourniquet deflation. Our study addresses this clinical gap by evaluating a combined pre-release perfusion pressure and early dynamic volume index (intuPVi) bedside risk assessment framework under real-world clinical constraints. Accordingly, we prospectively evaluated whether pre-release blood pressure and PVi could serve as useful predictors of tourniquet-release hypotension in elderly patients undergoing TKA under general anesthesia. We also present the findings with explicit acknowledgment of the limitations of intermittent noninvasive monitoring, exploratory secondary analyses, and modest sample size. 2. Materials and Methods 2.1. Study Design and Ethical Approval This single-center prospective observational study was conducted at a tertiary care hospital. The institutional review board approved the study protocol, and written informed consent was obtained from all participants. The study was performed in accordance with the Declaration of Helsinki and applicable institutional and national regulations. 2.2. Study Population Consecutive adult patients who underwent elective primary unilateral TKA under general anesthesia with a thigh tourniquet were screened. Inclusion criteria were age ≥ 65 years, elective unilateral TKA, use of a pneumatic thigh tourniquet with documented inflation and deflation times, and availability of noninvasive blood pressure and PVi measurements at predefined perioperative time points. Exclusion criteria were revision TKA or bilateral procedures, combined regional/general anesthesia with neuraxial block as the primary anesthetic, baseline arrhythmias that could invalidate dynamic preload indices, and missing hemodynamic or PVi data around the time of tourniquet release. Ninety patients met all criteria and were included in the final analysis. 2.3. Anesthesia and Tourniquet Management Anesthesia was induced with intravenous propofol (1–2 mg/kg), followed by a neuromuscular blocking agent to facilitate endotracheal intubation. Anesthesia was maintained with volatile anesthetics in oxygen/air and continuous remifentanil infusion. Patients were mechanically ventilated in volume-controlled mode with a tidal volume of approximately 6–8 mL/kg. A pneumatic thigh tourniquet was applied to the operative limb and inflated after exsanguination. Tourniquet pressure was generally set at 100–150 mmHg above systolic blood pressure and maintained until completion of the major surgical steps. Tourniquet inflation and deflation times were recorded and converted to minutes to calculate tourniquet duration. Intravenous fluids and vasoactive agents, including phenylephrine, ephedrine, or norepinephrine, were administered at the discretion of the attending anesthesiologist to maintain hemodynamic stability. 2.4. Monitoring Noninvasive blood pressure (NIBP) was measured on the contralateral arm at 1–5 min intervals. For analysis, we abstracted systolic and mean blood pressure values at key time points: baseline (iniSBP and iniMBP) immediately before induction; pre-release systolic and mean blood pressure (preRel_SBP and preRel_MBP), defined as the last values recorded within 5 min before tourniquet deflation (befoffSBP and befoffMBP); and the minimum systolic and mean blood pressures after tourniquet deflation (offSBP and offMBP) within a precisely defined post-deflation window of 10 min following tourniquet deflation. PVi was measured using a Radical-7 monitor with a rainbow sensor (Masimo Corp., Irvine, CA, USA). PVi values were recorded immediately before induction (iniPVi), immediately after endotracheal intubation (intuPVi), at or near tourniquet inflation (onPVi), during surgery at predefined intervals (inciPVi, 1hPVi), immediately before deflation (befoffPVi), and shortly after deflation (offPVi). Preliminary analyses from the pilot study suggested that PVi measured immediately after intubation (intuPVi) showed the clearest relationship with post-deflation blood pressure; therefore, intuPVi was selected as the primary PVi predictor in the present analysis. 2.5. Data Collection and Outcomes Demographic and clinical variables were extracted from electronic medical records, including age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status, history of hypertension (HTN) and diabetes mellitus (DM), anesthesia duration, surgery duration, tourniquet duration, crystalloid volume, and estimated blood loss (EBL). The primary outcome was tourniquet-release hypotension defined as offMBP < 65 mmHg (Severe_offMBP65), in line with prior large cohort studies linking intraoperative MBP < 65 mmHg to adverse outcomes [ 4]. Two secondary hypotension outcomes were evaluated for comparison: an absolute systolic definition (Severe_offSBP90, offSBP < 90 mmHg) and a relative systolic definition (Severe_pre20), defined as a ≥20% decrease in systolic blood pressure from pre-release values to the nadir after deflation. These secondary endpoints were included to examine whether the observed associations were consistent across commonly used absolute and relative blood pressure definitions and should be interpreted as supportive exploratory analyses rather than primary inferential outcomes. Postoperative outcomes of interest included postoperative nausea and vomiting (PONV), wound infection, postoperative pulmonary complication (PPC), urinary retention (need for Nelaton catheterization and postoperative urinary retention [POUR]), AKI, delirium, postoperative creatinine, glomerular filtration rate (GFR), and hospital length of stay (HLOS). 2.6. Sample Size Calculation and Statistical Analysis Based on a pilot study conducted at our institution in patients undergoing TKA, the correlation coefficient between the degree of blood pressure decrease at tourniquet release and PVi was 0.493. A G*Power (version 3.1; Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany) analysis (Exact test, Correlation: bivariate normal model, a priori computation of required sample size, two-tailed, correlation ρH1 = 0.493, α error probability = 0.01, power = 0.99, correlation ρH0 = 0) yielded a required sample size of 85 patients. Assuming a 5% dropout rate, we set the target enrollment at 90 patients. We acknowledge that while this sample size was calculated a priori based on the correlation coefficient as a primary surrogate of association, it was not specifically powered for higher-dimensional multivariable logistic regression or receiver operating characteristic (ROC) analysis, representing a limitation in statistical depth. Continuous variables are reported as mean ± standard deviation (SD) or median (interquartile range), as appropriate. Normality was assessed using the Shapiro–Wilk test and visual inspection of histograms. Between-group comparisons for the primary endpoint were performed using the Mann–Whitney U test for continuous variables and the chi-square or Fisher’s exact test for categorical variables. Univariate logistic regression analyses were first used to examine associations between each hypotension endpoint and clinically plausible predictors. Parsimonious multivariable logistic regression models were then constructed for each hypotension endpoint, including pre-release blood pressure, intuPVi, and HTN. Model performance was assessed using receiver operating characteristic analysis and the area under the curve (AUC). All statistical tests were two-sided, and p < 0.05 was considered statistically significant. Statistical analyses were performed using SPSS version 22.0 (IBM Corp., Armonk, NY, USA). 3. Results 3.1. Patient Characteristics and Incidence of Tourniquet-Release Hypotension A total of 90 elderly patients met the inclusion criteria and were included in the final analysis. Most patients were female (86.7%), and ASA physical status II was the most common classification (80.0%). The mean age was 73.88 ± 5.37 years, and the mean body mass index was 25.74 ± 3.03 kg/m 2. HTN and DM were present in 64.4% and 34.4% of patients, respectively. Baseline SBP and MBP were 171.18 ± 21.37 mmHg and 118.04 ± 14.90 mmHg, respectively. Pre-release SBP and MBP were 129.67 ± 19.89 mmHg and 94.33 ± 14.39 mmHg, whereas the nadir post-deflation SBP and MBP were 96.30 ± 14.11 mmHg and 70.87 ± 10.00 mmHg, respectively ( Table A1 Tourniquet-release hypotension, defined as offMBP < 65 mmHg, occurred in 26 of 90 patients (28.9%). The incidence of offSBP < 90 mmHg was 35.6%, and the incidence of a ≥20% decrease in SBP from pre-release values was 72.2%. Baseline and perioperative characteristics according to the presence of offMBP < 65 mmHg are summarized in . Patients with hypotension had significantly lower pre-release SBP and MBP than those without hypotension. Body mass index was also slightly lower in the hypotension group, whereas age, anesthesia duration, surgery duration, tourniquet duration, crystalloid volume, and estimated blood loss did not differ significantly between groups ( 3.2. Predictors of the Primary Endpoint Univariate logistic regression analysis showed that lower pre-release MBP was significantly associated with offMBP < 65 mmHg (odds ratio (OR), 0.94; 95% confidence interval (CI), 0.91–0.98; p = 0.003). Lower pre-release SBP was also associated with the primary endpoint (OR, 0.96; 95% CI, 0.94–0.99; p = 0.007). PVi measured immediately after endotracheal intubation (intuPVi) showed a borderline association with the primary endpoint (OR, 1.12; 95% CI, 1.00–1.25; p = 0.042). Other candidate predictors were not significantly associated with the primary endpoint ( In the multivariable model, pre-release MBP and intuPVi remained independently associated with offMBP < 65 mmHg. The adjusted OR was 0.95 (95% CI, 0.92–0.99; p = 0.012) for pre-release MBP and 1.12 (95% CI, 1.00–1.26; p = 0.042) for intuPVi. We acknowledge that the association between lower pre-release MBP and post-deflation hypotension is partly expected and mathematically related. However, including pre-release MBP in our multivariable model was essential to demonstrate that the dynamic index (intuPVi) provides independent and additive predictive information beyond the absolute blood pressure level immediately before deflation. The discriminatory performance of the combined model was moderate, with an AUC of 0.71 ( and Figure 1 3.3. Secondary Blood Pressure Outcomes For the secondary hypotension definitions, similar patterns were observed. Pre-release SBP and intuPVi were significantly associated with offSBP < 90 mmHg in the parsimonious multivariable model. In addition, both variables were associated with a ≥20% decrease in SBP from pre-release values to the post-deflation nadir ( The combined model showed an AUC of 0.76 for offSBP < 90 mmHg and 0.88 for the relative SBP decrease endpoint, indicating that pre-release SBP was particularly informative for the relative definition, whereas intuPVi provided modest additional discrimination ( 3.4. Exploratory Bedside Risk Stratification An exploratory bedside rule was assessed using thresholds of pre-release MBP < 86 mmHg and intuPVi ≥ 16. Patients with pre-release MBP < 86 mmHg had a higher incidence of offMBP < 65 mmHg than those with pre-release MBP ≥ 86 mmHg (50.0% vs. 21.2%). Similarly, patients with intuPVi ≥ 16 had a higher incidence of offMBP < 65 mmHg than those with intuPVi < 16 (52.2% vs. 20.9%). When both criteria were present, the incidence of offMBP < 65 mmHg was 71.4%, compared with 25.3% in all other patients. Because only seven patients met both criteria, this analysis should be interpreted as exploratory. The corresponding visual summary is provided in the Appendix B as Figure A1. 3.5. Postoperative Outcomes Postoperative outcomes according to the presence of offMBP < 65 mmHg are presented in . The incidences of PONV, wound infection, PPC, urinary retention, AKI, and delirium were similar between groups. Postoperative day 2 creatinine and GFR also did not differ significantly. HLOS was numerically shorter in patients with offMBP < 65 mmHg, but the difference was not statistically significant ( Overall, no clear association was observed between tourniquet-release hypotension and early postoperative complications in this cohort. 4. Discussion This prospective study in elderly patients undergoing TKA with a thigh tourniquet under general anesthesia demonstrates that pre-release MBP and PVi immediately after endotracheal intubation (intuPVi) are independent predictors of tourniquet-release hypotension when defined as offMBP < 65 mmHg. Similar associations were observed when hypotension was defined using a systolic threshold (offSBP < 90 mmHg) and a relative decrease of ≥20% from pre-release to nadir SBP after deflation. These findings suggest that both the blood pressure level immediately before tourniquet deflation and the degree of preload dependence early after induction jointly determine vulnerability to tourniquet-release hypotension in this population. The combined use of pre-release blood pressure and intuPVi improved the prediction of tourniquet-release hypotension compared with either variable alone, although the absolute gains in AUC were modest. Nevertheless, the overall discrimination of the parsimonious models was moderate for a simple bedside risk assessment tool. Using pre-release MBP < 86 mmHg and intuPVi ≥ 16 as pragmatic thresholds, we identified a high-risk subgroup in which Severe_offMBP65 occurred in 71.4%, compared with 25.3% in all other patients. This gradient in risk suggests that a two-dimensional assessment incorporating both the absolute perfusion pressure immediately before deflation (pre-release MBP) and a dynamic index of preload dependency and vascular reserve (intuPVi) may be more informative than either parameter alone for stratifying risk of tourniquet-release hypotension. Because model discrimination was only moderate and the high-risk subgroup was small, we propose this approach as a hypothesis-generating framework for future validation rather than as an immediate trigger for protocolized intervention. Despite these limitations, our findings suggest that pre-release MBP and PVi could serve as preliminary indicators to help identify elderly TKA patients who may be vulnerable to tourniquet-release hypotension. In a research context, this underscores the potential value of examining pre-release hemodynamic states rather than relying solely on post-deflation reactive measures. However, translating these findings into clinical practice—such as implementing proactive hemodynamic protocols or preemptively adjusting vasopressor dosing before tourniquet deflation—would be premature without prospective validation in larger, standardized cohorts. Future prospective multicenter studies should validate these observations, examine whether targeted interventions based on pre-release blood pressure and PVi can reduce the incidence and duration of tourniquet-release hypotension, and determine whether such strategies can ultimately improve patient-centered outcomes. 5. Conclusions Lower pre-release MBP and higher intuPVi were independently associated with tourniquet-release hypotension in elderly patients undergoing TKA under general anesthesia. These findings are hypothesis-generating and suggest that these variables may be useful for preliminary peri-deflation risk stratification. However, the findings must be interpreted cautiously because of the moderate model performance, intermittent noninvasive monitoring, post hoc selection, and the modest sample size. External validation in larger cohorts using standardized hemodynamic management protocols is required before these markers can be integrated into routine clinical practice. Author Contributions Conceptualization, S.L. and H.Y.K.; methodology, S.L. and H.Y.K.; software, S.L.; validation, J.E.K., Y.Y. and H.H.; formal analysis, S.L.; investigation, S.L., J.E.K. and Y.Y.; resources, H.Y.K.; data curation, S.L., J.E.K. and Y.Y.; writing—original draft preparation, S.L.; writing—review and editing, J.E.K., Y.Y., H.H. and H.Y.K.; visualization, S.L.; supervision, H.Y.K.; project administration, H.Y.K.; funding acquisition, H.Y.K. All authors have read and agreed to the published version of the manuscript. This research was funded by Kyung Hee University, grant number KHU-20233255. Institutional Review Board Statement The study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Review Board of Kyung Hee University Hospital (protocol code KHUH 2023-03-069 and date of approval: 28 April 2023). Informed Consent Statement Informed consent was obtained from all subjects involved in the study. Data Availability Statement Data can be obtained from the authors upon reasonable request. Acknowledgments We sincerely thank the clinical teams in the Department of Anesthesiology and Pain Medicine, Kyung Hee University Hospital, for their invaluable assistance. Conflicts of Interest The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results. Abbreviations The following abbreviations are used in this manuscript: AKI Acute kidney injury ASA American Society of Anesthesiologists AUC Area under the curve BMI Body mass index CI Confidence interval DM Diabetes mellitus EBL Estimated blood loss GFR Glomerular filtration rate HLOS Hospital length of stay HTN Hypertension MBP Mean blood pressure OR Odds ratio PONV Postoperative nausea and vomiting POUR Postoperative urinary retention PPC Postoperative pulmonary complication PVi Pleth variability index ROC Receiver operating characteristic SBP Systolic blood pressure TKA Total knee arthroplasty Appendix A Table A1. Baseline characteristics of study participants. Table A1. Baseline characteristics of study participants. Variable Value ( n = 90) Female 78 (86.7%) ASA class II 72 (80.0%) Age (years) ୭୩.୮୮ ବ୍ଦ ୫.୩୭ BMI (kg/m 2) ୨୫.୭୪ ବ୍ଦ ୩.୦୩ Hypertension 58 (64.4%) Diabetes mellitus 31 (34.4%) Baseline SBP (mmHg) ୧୭୧.୧୮ ବ୍ଦ ୨୧.୩୭ Baseline MBP (mmHg) ୧୧୮.୦୪ ବ୍ଦ ୧୪.୯୦ Pre-release SBP (mmHg) ୧୨୯.୬୭ ବ୍ଦ ୧୯.୮୯ Pre-release MBP (mmHg) ୯୪.୩୩ ବ୍ଦ ୧୪.୩୯ offSBP (mmHg) ୯୬.୩୦ ବ୍ଦ ୧୪.୧୧ offMBP (mmHg) ୭୦.୮୭ ବ୍ଦ ୧୦.୦୦ Anesthesia time (min) ୧୪୨.୮୩ ବ୍ଦ ୧୪.୬୯ Operation time (min) ୧୦୧.୦୦ ବ୍ଦ ୧୨.୮୫ Tourniquet time (min) ୯୨.୮୯ ବ୍ଦ ୯.୨୫ Appendix B Figure A1. Simplified bar chart showing the incidence of offMBP < 65 mmHg according to pre-release MBP (≥86 vs. <86 mmHg), intuPVi (<16 vs. ≥16), and a combined high-risk group (pre-release MBP < 86 mmHg and intuPVi ≥ 16). Risk strata (MBP < 86 mmHg, PVi ≥ 16, and the combined high-risk group) are shown as blue bars on the left of each pair. Figure A1. Simplified bar chart showing the incidence of offMBP < 65 mmHg according to pre-release MBP (≥86 vs. <86 mmHg), intuPVi (<16 vs. ≥16), and a combined high-risk group (pre-release MBP < 86 mmHg and intuPVi ≥ 16). Risk strata (MBP < 86 mmHg, PVi ≥ 16, and the combined high-risk group) are shown as blue bars on the left of each pair. Nham, F.H.; Patel, I.; Zalikha, L.; El-Othmani, M.M. Epidemiology of primary and revision total knee arthroplasty: Analysis of demographics, comorbidities and outcomes from the national inpatient sample. Arthroplasty 2023, 5] Girardis, M.; Milesi, S.; Donato, S.; Raffaelli, M.; Spasiano, A.; Antonutto, G.; Pasqualucci, A.; Pasetto, A. The hemodynamic and metabolic effects of tourniquet application during knee surgery. Anesth. Analg. 2000, 91] Okpara, S.; Lee, T.; Pathare, N.; Ghali, A.; Momtaz, D.; Ihekweazu, U. Cardiovascular Disease in Total Knee Arthroplasty: An Analysis of Hospital Outcomes, Complications, and Mortality. Clin. Orthop. 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The prevalence of knee osteoarthritis in elderly community residents in Korea. J. Korean Med. Sci. 2010, 25] Primorac, D.; Molnar, V.; Rod, E.; Jelec, Z.; Cukelj, F.; Matisic, V.; Vrdoljak, T.; Hudetz, D.; Hajsok, H.; Boric, I. Knee Osteoarthritis: A Review of Pathogenesis and State-Of-The-Art Non-Operative Therapeutic Considerations. Genes 2020, 11] Figure 1. Receiver operating characteristic (ROC) curves for predicting tourniquet-release hypotension, defined as offMBP < 65 mmHg. Curves are shown for pre-release mean blood pressure (MBP) alone, PVi measured immediately after endotracheal intubation (intuPVi) alone, and a combined logistic regression model including both predictors. The grey dotted line represents the reference line (AUC = 0.5). Figure 1. Receiver operating characteristic (ROC) curves for predicting tourniquet-release hypotension, defined as offMBP < 65 mmHg. Curves are shown for pre-release mean blood pressure (MBP) alone, PVi measured immediately after endotracheal intubation (intuPVi) alone, and a combined logistic regression model including both predictors. The grey dotted line represents the reference line (AUC = 0.5). Baseline characteristics and perioperative data according to tourniquet-release hypotension, defined as offMBP < 65 mmHg. Baseline characteristics and perioperative data according to tourniquet-release hypotension, defined as offMBP < 65 mmHg. Variable Non-Hypotension ( n = 64) Hypotension ( n = 26) p-Value Sex (male/female) 9/55 3/23 1.000 ASA class 1/2/3 13/47/4 1/25/0 0.049 Hypertension 38 (59.4%) 20 (76.9%) 0.115 Diabetes mellitus 23 (35.9%) 8 (30.8%) 0.640 Age (years) ୭୩.୩୧ ବ୍ଦ ୫.୫୯ ୭୫.୨୭ ବ୍ଦ ୪.୫୮ 0.072 BMI (kg/m 2) ୨୬.୦୪ ବ୍ଦ ୨.୮୭ ୨୫.୦୧ ବ୍ଦ ୩.୩୪ 0.045 Baseline SBP (mmHg) ୧୬୯.୮୦ ବ୍ଦ ୨୧.୪୨ ୧୭୪.୫୮ ବ୍ଦ ୨୧.୨୬ 0.308 Baseline MBP (mmHg) ୧୧୭.୭୮ ବ୍ଦ ୧୩.୮୫ ୧୧୮.୬୯ ବ୍ଦ ୧୭.୪୯ 0.782 Pre-release SBP (mmHg) ୧୩୩.୩୯ ବ୍ଦ ୨୦.୨୨ ୧୨୦.୫୦ ବ୍ଦ ୧୫.୯୬ 0.003 Pre-release MBP (mmHg) ୯୭.୩୮ ବ୍ଦ ୧୪.୧୬ ୮୬.୮୫ ବ୍ଦ ୧୨.୨୩ 0.001 offSBP (mmHg) ୧୦୨.୧୬ ବ୍ଦ ୧୧.୮୨ ୮୧.୮୮ ବ୍ଦ ୭.୨୬ <0.001 offMBP (mmHg) ୭୫.୪୮ ବ୍ଦ ୭.୬୨ ୫୯.୫୦ ବ୍ଦ ୪.୫୬ <0.001 Anesthesia time (min) ୧୪୩.୦୫ ବ୍ଦ ୧୩.୪୪ ୧୪୨.୩୧ ବ୍ଦ ୧୭.୬୮ 0.391 Operation time (min) ୧୦୧.୪୭ ବ୍ଦ ୧୨.୦୩ ୯୯.୮୫ ବ୍ଦ ୧୪.୮୭ 0.532 Tourniquet time (min) ୯୩.୭୦ ବ୍ଦ ୮.୫୯ ୯୦.୮୮ ବ୍ଦ ୧୦.୬୩ 0.145 Crystalloid volume (mL) ୩୨୧.୮୮ ବ୍ଦ ୧୧୦.୧୫ ୨୮୦.୭୭ ବ୍ଦ ୧୦୫.୯୦ 0.117 Estimated blood loss (mL) ୪୨.୬୬ ବ୍ଦ ୨୧.୯୮ ୩୮.୪୬ ବ୍ଦ ୨୪.୧୨ 0.223 Values are presented as the mean ± SD or number (%). ASA, American Society of Anesthesiologists; BMI, body mass index; SBP, systolic blood pressure; MBP, mean blood pressure. Univariate predictors of tourniquet-release hypotension, defined as offMBP < 65 mmHg. Univariate predictors of tourniquet-release hypotension, defined as offMBP < 65 mmHg. Predictor OR (95% CI) p-Value Pre-release MBP (mmHg) 0.94 (0.91–0.98) 0.003 Pre-release SBP (mmHg) 0.96 (0.94–0.99) 0.007 intuPVi 1.12 (1.00–1.25) 0.042 inciPVi 1.10 (0.99–1.22) 0.085 Crystalloid volume (mL) 1.00 (0.99–1.00) 0.111 Hypertension 2.28 (0.81–6.45) 0.120 Age (years) 1.07 (0.98–1.17) 0.120 BMI (kg/m 2) 0.89 (0.75–1.04) 0.147 Tourniquet time (min) 0.97 (0.92–1.02) 0.192 onPVi 1.06 (0.95–1.19) 0.290 Baseline SBP (mmHg) 1.01 (0.99–1.03) 0.336 Cerebrovascular disease 1.96 (0.41–9.43) 0.403 Cardiac disease 1.76 (0.45–6.83) 0.415 Estimated blood loss (mL) 0.99 (0.97–1.01) 0.428 Surgical time (min) 0.99 (0.95–1.03) 0.586 Diabetes mellitus 0.79 (0.30–2.10) 0.640 1hPVi 1.01 (0.94–1.09) 0.707 offPVi 1.02 (0.91–1.14) 0.771 Baseline MBP (mmHg) 1.00 (0.97–1.04) 0.792 iniPVi 1.01 (0.95–1.06) 0.815 befoffPVi 1.01 (0.93–1.10) 0.820 Anesthesia time (min) 1.00 (0.97–1.03) 0.828 OR, odds ratio; CI, confidence interval; BMI, body mass index; MBP, mean blood pressure; SBP, systolic blood pressure; PVi, pleth variability index. Parsimonious multivariable models for different definitions of tourniquet-release hypotension. Parsimonious multivariable models for different definitions of tourniquet-release hypotension. Outcome Predictor Adjusted OR (95% CI) p-Value Model AUC offMBP < 65 mmHg Pre-release MBP 0.95 (0.92–0.99) 0.012 0.71 intuPVi 1.12 (1.00–1.26) 0.042 offSBP < 90 mmHg Pre-release SBP 0.96 (0.94–0.99) 0.006 0.76 intuPVi 1.15 (1.02–1.29) 0.018 ≥20% decrease in SBP Pre-release SBP 1.12 (1.06–1.18) <0.001 0.88 intuPVi 1.20 (1.02–1.40) 0.029 OR, odds ratio; CI, confidence interval; MBP, mean blood pressure; SBP, systolic blood pressure; PVi, pleth variability index; AUC, area under the receiver operating characteristic curve. Postoperative outcomes according to tourniquet-release hypotension, defined as offMBP < 65 mmHg. Postoperative outcomes according to tourniquet-release hypotension, defined as offMBP < 65 mmHg. Outcome Non-Hypotension ( n = 64) Hypotension ( n = 26) p-Value PONV 27/63 (42.9%) 9/25 (36.0%) 0.555 Wound infection 1/64 (1.6%) 0/26 (0.0%) 1.000 PPC 4/64 (6.2%) 1/26 (3.8%) 1.000 Nelaton catheterization 35/64 (54.7%) 15/26 (57.7%) 0.795 POUR 40/64 (62.5%) 16/26 (61.5%) 0.932 AKI 0/64 (0.0%) 1/26 (3.8%) 0.289 Delirium 8/64 (12.5%) 5/26 (19.2%) 0.510 CrPOD2 ୦.୬୨ ବ୍ଦ ୦.୨୬ ୦.୬୧ ବ୍ଦ ୦.୧୮ 0.627 GFRPOD2 ୧୧୦.୦୦ ବ୍ଦ ୩୩.୫୬ ୧୦୮.୩୧ ବ୍ଦ ୩୪.୭୬ 0.454 HLOS ୯.୯୫ ବ୍ଦ ୪.୧୦ ୮.୫୮ ବ୍ଦ ୩.୯୨ 0.167 PONV, postoperative nausea and vomiting; PPC, postoperative pulmonary complication; POUR, postoperative urinary retention; AKI, acute kidney injury; CrPOD2, creatinine on postoperative day 2; GFRPOD2, glomerular filtration rate on postoperative day 2; HLOS, hospital length of stay. Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. © 2026 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license. Share and Cite MDPI and ACS Style Lee, S.; Kim, J.E.; Yang, Y.; Hong, H.; Kang, H.Y. Blood Pressure and Pleth Variability Index as Predictors of Tourniquet-Release Hypotension in Elderly Patients Undergoing Total Knee Arthroplasty: A Prospective Observational Study. Life 2026, 16, 973. https://doi.org/10.3390/life16060973 AMA Style Lee S, Kim JE, Yang Y, Hong H, Kang HY. Blood Pressure and Pleth Variability Index as Predictors of Tourniquet-Release Hypotension in Elderly Patients Undergoing Total Knee Arthroplasty: A Prospective Observational Study. Life. 2026; 16(6):973. https://doi.org/10.3390/life16060973 Chicago/Turabian Style Lee, Sangho, Jung Eun Kim, Yeji Yang, Harin Hong, and Hee Yong Kang. 2026. "Blood Pressure and Pleth Variability Index as Predictors of Tourniquet-Release Hypotension in Elderly Patients Undergoing Total Knee Arthroplasty: A Prospective Observational Study" Life 16, no. 6: 973. https://doi.org/10.3390/life16060973 APA Style Lee, S., Kim, J. E., Yang, Y., Hong, H., & Kang, H. Y. (2026). Blood Pressure and Pleth Variability Index as Predictors of Tourniquet-Release Hypotension in Elderly Patients Undergoing Total Knee Arthroplasty: A Prospective Observational Study. Life, 16(6), 973. https://doi.org/10.3390/life16060973 Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here. Article Metrics Article metric data becomes available approximately 24 hours after publication online.
