Ultrasound Guided Fluid Loading Before Spinal Anesthesia

In the literature, numerous studies have compared the different pre-filling and co-filling protocols with different solutes. The majority of them conclude that co-filling is superior to pre-filling when the same type of solute is used. Pre-filling with crystalloids was then abandoned in favor of co-filling with crystalloids It is essential to remember that several invasive or non-invasive means of hemodynamic monitoring have previously been validated in pregnant women The use of invasive tools for assessing blood volume, particularly arterial and central venous catheters, is limited given the brevity of obstetric procedures, the risk of morbidity in awake patients and their high costs. Although non-invasive methods are preferable, some remain imperfect, notably carotid Doppler and bioimpedance devices Transthoracic echocardiography stands out as a particularly reliable and relevant non-invasive tool for assessing cardiac output and blood volume in parturients It allows analysis of the variation of the subaortic velocity time integral (∆ ITV s-a) during the passive leg raise test (LET). It is the only dynamic preload parameter validated in patients during spontaneous ventilation, thus allowing assessment of blood volume.

After reviewing the literature, the investigators found no studies about, exclusively hypovolemic patients, the effect of combining pre-filling with co-filling with crystalloids, monitored by echocardiographic preload-dependence indices, on the incidence of arterial hypotension during elective cesarean sections performed under spinal anesthesia.

In this study, monitoring was performed by transthoracic echocardiography, based on the variation in subaortic TVI following the passive leg raise test and vascular fluid tests.

The objective of this prospective randomized study was to evaluate the efficacy of ultrasound-guided correction of hypovolemia by pre-filling with crystalloids on the incidence of arterial hypotension during elective cesarean sections performed under spinal anesthesia.

• C (Drug), also known as isotonic saline solution preloading: isotonic saline solution infusion (fluid preloading) to achieve correction of hypovolemia before spinal anesthesia using cardiac ultrasoud guidance by measurment of VTI variation after a 250ml saline solution loading, with a maximum of 4 challenges, until hypovolemia complete correction
• T (Drug), also known as isotonic saline solution coloading with ephedrine boluses: isotonic saline solution coloading after spinal anesthesia associated with recsue boluses of Ephedrine would be the "standard of care" in this arm. No correction of hypovolemia is done before spinal anesthesia. parturients receive a cristalloid coloading with saline isotonic solution with rescue boluses of ephedrine if hypotesion happens after spinal anesthesia

Primary outcomes

• incidence of post-spinal anesthesia arterial hypotension during surgery [60 minutes]: The incidence of intraoperative post-spinal hypotension Defined by a drop in blood pressure (BP) of more than 20% of its reference value, or a blood pressure (BP) < 100 mmHg

Secondary outcomes

• Time to onset of the first episode of arterial hypotension (min) [60 minutes]: hypotension is Defined by a drop in SBP of more than 20% of its reference value, or a SBP < 100mmHg
• Duration of hypotensive episode (min) [60 minutes]: the duration of hypotension from the onset of the first episode until reaching normal ranges again
• Depth of hypotension (% fall from baseline value) [60 minutes]: hypotension is Defined by a drop in SBP of more than 20% of its baseline value, or a SBP < 100mmHg
• Variation in intraoperative cardiac output (% drop from baseline) [60 minutes]: cardiac output is expected to rise of fall from its baseline and is caculated in percenttages of variation from its baseline
• Consumption of per-op vasopressors (mg of ephedrine) [60 minutes]: total dose of ephedrine given in case of hypotension
• Volume of cristalloids and colloids infused (ml) [60 minutes]: total volume of critalloids given either when preloading bfeore spinal anesthesia or while coloading after spinal anesthesia
• Incidence of maternal bradycardia (%) - [60 minutes]: (Heart Rate < 50 bpm)
• Incidence of intraoperative nausea and vomiting (%) [60 minutess]: nausea and vomiting usually at the moments of severe hypotension
• Fetal pH at the umbilical cord at birth. [30 minutes]: right after delivery
• Newborn APGAR score at the first and fifth minute [30 minutes]: at birth

Sex: Female, ages: 18 Years to 50 Years, accepts healthy volunteers

Inclusion Criteria:

ASA II score, singleton pregnancy cesarean section

Exclusion Criteria:

Spinal anesthesia failure general anesthesia postpartum hemorhage saline solution volume > 1000 ml for preloading echocardiography: difficulties Poor echogenicity

• Results publication: Ben Marzouk S, Fouzai B, Dhraief N, Ben Amor F, Hkiri T, Hamdi H, Trablesi S, Kalai A, Maghrebi H. Cardiac ultrasound-guided crystalloid preloading before spinal anesthesia vs. standard coloading for scheduled cesarean delivery: a randomized controlled trial. Int J Obstet Anesth. 2026 May;66:104840. doi: 10.1016/j.ijoa.2025.104840. Epub 2025 Dec 29. PMID 41529542