An observational study in Cardiac Arrhythmia and Anesthesia, sponsored by Istanbul University. Not yet recruiting. Open to participants aged 18 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-05-07.
Sponsored by Istanbul University · Observational
Laparoscopic cholecystectomy procedures involve pneumoperitoneum and volatile anesthetics, both of which can significantly influence cardiovascular physiology and autonomic balance. While volatile anesthetics are known to affect myocardial repolarization, the specific impact of Low-Flow Anesthesia (LFA)-a cost-effective and environmentally friendly technique-on these cardiac markers remains under-researched.
This prospective observational study aims to compare the effects of low-flow versus normal-flow sevoflurane anesthesia on two critical non-invasive biomarkers of ventricular repolarization: the Frontal QRS-T angle and the Tp-e interval. These parameters are essential for predicting electrical instability and the risk of malignant arrhythmias. The study will evaluate a total of 128 patients to determine whether different fresh gas flow rates lead to significant changes in cardiac electrophysiological stability during the perioperative and early postoperative periods.
This prospective observational study is designed to investigate the electrophysiological effects of different fresh gas flow rates during sevoflurane anesthesia in patients undergoing elective laparoscopic cholecystectomy. Laparoscopic procedures involving pneumoperitoneum and volatile anesthetics are known to influence autonomic nervous system balance and cardiovascular stability. While the impact of inhalation agents on myocardial repolarization is documented, the specific effects of Low-Flow Anesthesia (LFA)-an environmentally and economically favorable technique-on markers of electrical instability remain to be fully elucidated. The primary objective is to evaluate and compare the effects of low-flow and normal-flow sevoflurane techniques on the Frontal QRS-T angle and the Tp-e interval, which serve as critical non-invasive biomarkers for predicting malignant arrhythmia risk and reflecting the transmural distribution of ventricular repolarization.
The study protocol involves 128 patients, a sample size determined by power analysis (80% power, 0.05 alpha) to account for a predicted 35% difference between groups and potential dropouts. Patients are observationally assigned to either the Low-Flow Group (LFG) or the Normal-Flow Group (NFG) according to routine clinical practice. Following a standardized induction and an initial stabilization phase at 4-6 L/min, flow rates are adjusted once the target concentration (MACage +1) is reached: the LFG is reduced to 0.5 L/min, while the NFG is maintained at 2 L/min. Ventilation is managed to keep EtCO2 between 35-45 mmHg. Data collection is performed via high-resolution ECG recordings at four time points: preoperative baseline (T1), 5 minutes post-intubation (T2), 15 minutes post-intubation (T3), and 15 minutes postoperatively (T4).
Another key focus of this research is the detailed analysis of secondary outcomes, including the monitoring of hemodynamic stability (mean arterial pressure and heart rate) across all time points. Furthermore, the study aims to characterize the electrophysiological profile of each technique by analyzing the Tp-e/QT ratio and calculating time-dependent variations in repolarization parameters, specifically the delta changes from baseline to intraoperative stages (ΔT1-T2 and ΔT1-T3). Additionally, a cost-effectiveness analysis will be conducted by determining the total volume of volatile anesthetic consumed in both techniques. Statistical analysis will involve independent samples t-tests for inter-group comparisons, while repeated measures ANOVA with Bonferroni correction will evaluate time-dependent changes. Pearson correlation analysis will be utilized to assess the relationships between continuous variables, providing a comprehensive assessment of the safety and efficacy of low-flow versus normal-flow anesthesia management.
885 studies on the registry are indexed under Arrhythmias, Cardiac; 235 are open to participants now.
This study's planned enrollment of 128 is below the median of 200 across 414 observational studies indexed under Arrhythmias, Cardiac.
Browse Arrhythmias, Cardiac studies →Istanbul University is the lead sponsor of 496 studies on the registry; 79 are open to participants now.
Of its 5 completed or terminated interventional studies of FDA-regulated products, 1 (20%) have results posted.
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The study population consists of adult patients (aged 18 years and older) scheduled for elective or semi-elective laparoscopic cholecystectomy at a tertiary care training and research hospital.
Exclusion Criteria:
Anesthesia induction and initial stabilization (first 6-8 minutes at 4-6 L/min) follow standard hospital protocols. Fresh Gas Flow (FGF) reduced to 0.5 L/min after the target concentration (MACage +1) is reached. Ventilation parameters are adjusted to maintain end-tidal carbon dioxide (EtCO2) between 35-45 mmHg with a minimum FiO2 of 0.30. Volatile anesthetics are discontinued 15 minutes before the estimated end of surgery. Pre-oxygenation and wash-out are performed at 5-6 L/min with 80% oxygen prior to extubation.
Procedure: low flow anesthesia
Anesthesia induction and initial stabilization (first 6-8 minutes at 4-6 L/min) follow standard hospital protocols. Fresh Gas Flow (FGF) maintained at 2 L/min during anesthesia maintenance. Ventilation parameters are adjusted to maintain end-tidal carbon dioxide (EtCO2) between 35-45 mmHg with a minimum FiO2 of 0.30. Volatile anesthetics are discontinued 15 minutes before the estimated end of surgery. Pre-oxygenation and wash-out are performed at 5-6 L/min with 80% oxygen prior to extubation.
Fresh Gas Flow (FGF) reduced to 0.5 L/min after the target concentration (MACage +1) is reached.
Frontal QRS-T angle
electrocardiogram
Time frame: Pre-operative period, 5 minutes after induction, 15 minutes after induction, post operative 15th minute
Tp-e interval
electrocardiogram
Time frame: Pre-operative period, 5 minutes after induction, 15 minutes after induction, post-operative 15th minute
blood pressure
Non-invasive blood pressure (NIBP) monitor
Time frame: during peri-operative period
heart rate
electrocardiogram
Time frame: during peri-operative period
Tp-e/QT ratio
electrocardiogram
Time frame: Pre-operative period, 5 minutes after induction, 15 minutes after induction, post-operative 15th minute
Total amount of volatile anesthetic consumed
Mindray anesthesia machine
Time frame: end of operation
Total amount of Remifentanil consumed
infusion pump
Time frame: end of operation
No study locations are listed for this record.
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Istanbul University