Corrected Carotid Flow Time for Predicting Spinal Anesthesia-induced Hypotension

Spinal anaesthesia is a standard technique frequently preferred for caesarean section. However, spinal anaesthesia-induced hypotension remains a critical problem causing undesirable maternal symptoms such as nausea, vomiting and dyspnoea and adverse consequences for umbilical acidosis and the fetus. One of the reasons aggravating hypotension is aortocaval compression of the growing uterus and consequent decrease in preload and stroke volume . Therefore, left lateral tilt position is recommended in pregnant women after the 20th gestational week to prevent supine hypotension. This position decreases uterine compression on the vena cava and increases venous return to the heart and thus stroke volume. Recently, carotid artery Doppler has been used to assess stroke volume. Many studies have shown that carotid corrected flow time increases significantly after expansion of intravascular volume in hypovolaemic patients . In one study, it was reported that the change in carotid artery blood flow time induced by passive leg raising predicts fluid sensitivity in critically ill patients. It has been reported that changes in carotid artery blood flow time against hemodynamic interventions (such as Trendelenburg position) reflect maternal hypovolemic status and distinguish hypovolemic patients with a higher risk of spinal anesthesia-related hypotension. The investigators also think that the left lateral tilt position may increase the corrected carotid flow time by affecting hemodynamics and may differentiate the patient with a high risk of hypotension.

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Key information

Conditions

Hypotension Cardiovascular Diseases Vascular Diseases

Age range

18 year–40 year

Sex eligibility

Female

Study type

Observational

About this study

Patients undergoing elective cesarean section under spinal anesthesia will be included in the study. Carotid corrected flow time will be measured by Doppler ultrasonography in the supine and left lateral tilt (15°) positions before spinal anesthesia. Flow time will be measured using pulse Doppler waveforms in the long axis of the right common carotid artery. The measured flow time will be calculated as "corrected flow time" using the following Wodey formula; Carotid corrected flow time = measured flow time + [1.29 (Heart rate - 60)].

After standard monitoring (Electrocardiography, peripheral oxygen saturation, noninvasive blood pressure measurement), routine spinal anesthesia will be performed without any study-specific changes. The noninvasive blood pressure value measured before spinal anesthesia will be taken as the baseline value and a decrease of 20% or more in this value or a decrease in systolic blood pressure below 100 mmHg will be considered as "spinal anesthesia induced hypotension". Patients will be divided into those who develop spinal anesthesia-induced hypotension and those who do not develop spinal anesthesia-induced hypotension after spinal anesthesia and carotid corrected flow times will be compared between both groups.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Full-term pregnancy
physical status II of American Society of Anesthesiologists

Exclusion criteria

emergency cesarean section,
cesarean under general anesthesia
gestational Diabetes Mellitus
gestational Hypertension
preeclampsia,
cardiovascular disease
cerebrovascular disease
chronic kidney disease disease

Treatment and study plan

Primary outcomes

predictive value of the carotid flow time alteration

Time frame: 10-15 minute

rate of prediction

Sponsors and collaborators

Lead sponsor

Selcuk University

Other

Registry information

Official study title

The Effect of Carotid Corrected Blood Flow Time Measured in the Left Lateral Tilt Position on the Prediction of Spinal Anaesthesia-induced Hypotension in Caesarean Section

Important dates

Study start: 2025
Primary completion: 2025
Study completion: 2025
First posted: Apr 1, 2025
Registry last updated: Apr 9, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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