Description

This study will be conducted as a prospective observational trial at SBÜ Dr. Abdurrahman Yurtaslan Oncology Training and Research Hospital, Department of Anesthesiology and Reanimation, with the aim of evaluating the incidence and risk factors of post-induction hypotension (PIH) in geriatric oncology patients. The study will commence after institutional ethics committee approval, and written informed consent will be obtained from all participants.

Standard monitoring (ECG, non-invasive blood pressure, SpO₂) will be applied in the operating room. Pre-induction values will be recorded after a 5-minute rest period. Perfusion index (PI) and pleth variability index (PVI) will be measured using the Massimo Root® with Radical-7 monitor from the non-cannulated hand, with three consecutive readings averaged.

Demographic data (age, sex, height, weight, BMI), comorbidities, regular medications, type of malignancy, history of chemotherapy/radiotherapy, and preoperative laboratory values will be documented.

Anesthesia induction will be performed with propofol (1.5-2.5 mg/kg), fentanyl (1-2 μg/kg), lidocaine (1-1.5 mg/kg), and rocuronium (0.6 mg/kg). Maintenance will be achieved using sevoflurane (1.5-2%) or desflurane (5-6%), O₂/air mixture, and remifentanil (0.1-0.2 μg/kg/min). Drugs and doses used during induction will be recorded.

PIH is defined as hypotension occurring within the first 20 minutes after induction, prior to surgical stimulation. Criteria:

A ≥30% decrease in mean arterial pressure (MAP) compared to baseline or MAP \< 65 mmHg Any interventions for hypotension (vasopressors, intravenous fluids) will be documented.

Blood pressure measurements will be obtained at six time points:

T0: Baseline, before induction T1: After induction, prior to intubation T2: 1 minute after intubation T3: 5 minutes after intubation T4: 10 minutes after intubation T5: 15 minutes after intubation

The study will be completed after the T5 measurement, covering the first \~20 minutes following anesthesia induction.

In this study, post-induction hypotension (PIH) will be defined as either a ≥30% decrease in mean arterial pressure (MAP) compared to the pre-induction baseline value, or MAP \< 65 mmHg. The pre-induction MAP measured non-invasively will be taken as the baseline. During the first 20 minutes after induction (measured every 2 minutes), patients meeting either criterion will be classified into the "PIH present" group, while those without such changes will be classified as "PIH absent."

Sample size calculations were performed using G\*Power 3.1:

For group comparisons: Assuming a medium effect size (Cohen's d = 0.5), 80% power, and α = 0.05, 64 patients per group (128 total) are required.

For categorical variables: With a medium effect size (Cohen's w = 0.3), 108 participants are required.

For logistic regression: Based on literature, the incidence of PIH was estimated at 20%. Assuming an Odds Ratio (OR) of 2.0, a two-tailed test with 80% power and α = 0.05 indicated that at least 113 participants are needed.

All statistical analyses will be conducted using SPSS or equivalent software, with a significance threshold of p \< 0.05.