Pupillary Light Reflex to Predict Post-Spinal Hypotension in Elective Cesarean Delivery

Pupillary Light Reflex for Predicting Hypotension Risk After Spinal Anesthesia for Elective Cesarean Section: A Prospective Observational Cohort Study

This prospective observational cohort study investigates whether pre-anesthetic pupillary light reflex (PLR) parameters can predict the risk of hypotension following spinal anesthesia in women undergoing elective cesarean section. Spinal anesthesia-induced hypotension is common, with reported incidence rates of 50-90%, and current predictors such as baseline blood pressure and BMI have limited accuracy. PLR, a sensitive marker of autonomic nervous system balance, may offer a simple, objective, and non-invasive tool for identifying patients at higher risk. The study evaluates pupillary reaction latency and other PLR parameters and correlates them with post-spinal blood pressure changes to determine their predictive value.

Study Overview

• Status: Not yet recruiting
• Conditions: Hypotension; Spinal Anesthesia; Cesarean Delivery
• Intervention / Treatment: Other: Not applicable- observational study

Detailed Description

Spinal anesthesia is the standard technique for elective cesarean delivery, yet it is frequently associated with maternal hypotension due to sympathetic blockade. According to the study protocol, spinal anesthesia-induced hypotension (SAIH) occurs in 50-90% of cases, and currently available predictors-including baseline blood pressure, BMI, and block height-demonstrate limited accuracy (AUC <0.65). The pupillary light reflex (PLR) is a sensitive indicator of autonomic nervous system balance, and pupillary reaction latency may reflect parasympathetic conduction efficiency. As noted in the protocol, no published studies have evaluated PLR as a predictor of hypotension after spinal anesthesia in obstetric patients.

This prospective observational cohort study aims to determine whether pre-anesthetic PLR parameters, particularly pupillary reaction latency, can predict the occurrence and severity of hypotension following spinal anesthesia for elective cesarean section. Additional pupillometry parameters-including baseline diameter, constriction velocity, and minimum diameter-will also be assessed. Measurements are obtained using a handheld pupillometer after 5 minutes of dark adaptation, with three readings taken at 60-second intervals.

Following spinal anesthesia with hyperbaric bupivacaine and fentanyl, maternal blood pressure is monitored every 5 minutes for the first 20 minutes. The primary outcome is hypotension, defined as a >20% decrease in systolic blood pressure. Secondary outcomes include severe hypotension, vasopressor requirements, maternal symptoms, and neonatal Apgar scores and umbilical artery pH.

Statistical analysis includes ROC curve evaluation, Youden's index for cutoff determination, and multivariate logistic regression. The study involves no interventions beyond routine care, and pupillometry is non-invasive and safe. Findings may support the development of a novel, objective, and clinically useful predictor for SAIH in obstetric anesthesia.

• Study Type: Observational
• Enrollment (Estimated): 200

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Pregnant women (ASA II), aged 18-45 years, with term singleton pregnancies undergoing elective cesarean section under spinal anesthesia at Al-Azhar University Hospital, Damietta. Participants are evaluated using pre-anesthetic pupillometry and routine perioperative monitoring.

Description

Inclusion Criteria:

ASA II Term pregnancy ≥37 weeks Singleton pregnancy Elective cesarean section Age 18-45 years Written informed consent

Exclusion Criteria:

Emergency cesarean section Hypertensive disorders Diabetes mellitus Cardiovascular disease Neurological or autonomic disorders Ophthalmic disease Medications affecting autonomic function BMI >40 kg/m² Failed spinal anesthesia

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Elective Cesarean Section Cohort; Pregnant women (ASA II, term ≥37 weeks) undergoing elective cesarean section under spinal anesthesia. Participants undergo pre-anesthetic pupillometry and routine perioperative monitoring. No interventions are administered beyond standard clinical care.	Other: Not applicable- observational study; This study does not involve any investigational drugs, devices, or therapeutic interventions. Pupillometry is a non-invasive measurement performed as part of the observational assessment and is not considered an intervention.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Hypotension After Spinal Anesthesia	Hypotension defined as a >20% decrease in systolic blood pressure from baseline within the first 20 minutes after spinal anesthesia administration. Blood pressure is measured every 5 minutes as per protocol.	0-20 minutes after spinal anesthesia

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Severe Hypotension	Severe hypotension defined as systolic blood pressure <80 mmHg or requiring vasopressor administration.	0-20 minutes after spinal anesthesia
Total Vasopressor Dose Administered	Total amount of vasopressor medication administered to treat hypotension following spinal anesthesia.	Intraoperative period (first 20 minutes post-spinal)
Maternal Symptoms Associated With Hypotension	Assessment of maternal symptoms including nausea, vomiting, dizziness, or discomfort associated with hypotension.	Intraoperative period
Neonatal Apgar Scores	Apgar scores at 1 and 5 minutes after delivery.	1 minute and 5 minutes postpartum
Umbilical Artery pH	Measurement of umbilical artery blood pH to assess neonatal acid-base status.	Immediately after delivery

Collaborators and Investigators

• Sponsor: Al-Azhar University

Study record dates

Study Major Dates

• Study Start (Estimated): June 28, 2026
• Primary Completion (Estimated): September 30, 2026
• Study Completion (Estimated): October 31, 2026

Study Registration Dates

• First Submitted: June 25, 2026
• First Submitted That Met QC Criteria: June 25, 2026
• First Posted (Actual): July 1, 2026

Study Record Updates

• Last Update Posted (Actual): July 1, 2026
• Last Update Submitted That Met QC Criteria: June 25, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Hypotension; Cesarean Section; Spinal Anesthesia; Pupillometry; Obstetric Anesthesia; Pupillary Light Reflex
• Additional Relevant MeSH Terms: Vascular Diseases; Cardiovascular Diseases; Hypotension
• Other Study ID Numbers: DFM-IRB 00012367- 26-06-005

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No