Hemodynamic Effects of Lithotomy Position in Surgical Patients (PH-LITHO)

This prospective, randomized clinical study was conducted at Karadeniz Technical University Faculty of Medicine after receiving ethics committee approval (Protocol No: 2021/268)

• The study included 60 patients aged 65-80, classified as ASA II-III, who had been diagnosed with hypertension and on stable medication for at least 6 months

Randomization and Blinding: Participants were randomized into two groups (n=30 each) using computer-based random number generation

• Allocation was concealed using sequentially numbered envelopes
• Researchers involved in data recording and statistical analysis were blinded to the group assignments

Anesthesia Protocol: All patients received standard monitoring (ECG, SpO₂, and non-invasive blood pressure) and were sedated with intravenous midazolam (0.05 mg/kg) and fentanyl (1 µg/kg)

• Following a 3-minute rest in the supine position, Group L patients were moved to the lithotomy position for 120 seconds before induction, while Group S remained in the supine position
• Anesthesia was induced with 3-5 mg/kg thiopental administered over 120 seconds
• A laryngeal mask airway (LMA) was inserted at the 60th second post-induction
• Maintenance of anesthesia was achieved with desflurane (BIS target: 40-60) and remifentanil infusion

Hemodynamic Monitoring and Intervention: Non-invasive blood pressure (NIBP) was measured immediately after induction (Minute 0) and every minute thereafter for the first 5 minutes

• Post-induction hypotension (PIH) was defined as a Mean Arterial Pressure (MAP) falling below 65 mmHg or a decrease of more than 20% from the baseline value
• In the event of hypotension, 5 mg of intravenous ephedrine was administered as a rescue medication

Statistical Analysis: Sample size was calculated based on a 20% expected difference in PIH incidence, requiring 27 patients per group for 95% power

. Statistical analyses were performed using IBM SPSS v23.0, including t-tests, Mann-Whitney U tests, and Kaplan-Meier analysis for time-to-event (onset of hypotension)

Inclusion criteria

• Aged between 65 and 80 years.
• American Society of Anesthesiologists (ASA) physical status class II or III.
• Clinical diagnosis of hypertension.
• Continuous use of the same antihypertensive medication for at least 6 months.
• Scheduled for elective surgery requiring the lithotomy position.

Exclusion criteria

• Uncontrolled hypertension.
• Arrhythmias requiring medical treatment.
• Left ventricular ejection fraction (LVEF) < 40%.
• Unstable ischemic heart disease.
• Physical inability to be placed in the lithotomy position.