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

Does the Pre-induction Lithotomy Position Reduce Post-induction Hypotension in Geriatric Hypertensive Patients? A Prospective Randomized Study

Anesthesia-induced hypotension is a common occurrence in elderly hypertensive patients and is closely associated with increased postoperative morbidity

• This study aims to investigate whether the lithotomy position, a non-pharmacological and cost-free approach, can reduce the incidence of post-induction hypotension (PIH) in this high-risk population by increasing venous return

Sixty patients aged 65-80 with a history of hypertension were randomly assigned to either the Supine Group (Group S) or the Lithotomy Group (Group L)

• In Group L, patients were placed in the lithotomy position 120 seconds before the start of anesthesia induction
• Blood pressure was monitored every minute for the first five minutes following induction
• The study evaluates whether this simple positioning strategy can maintain hemodynamic stability, reduce the drop in mean arterial pressure, and decrease the overall need for vasopressor medications like ephedrine

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.