This prospective, randomized, controlled study was approved by the Ministry of Health
Istanbul Medeniyet University Göztepe Training and Research Hospital Clinical Research
Ethics Committee (approval number 2022/0263, dated 27 April 2022).
A total of 120 patients, aged 18 years and older and planned for gynaecological pelvic
surgery with an American Society of Anaesthesiologists (ASA) physical status score of
I-III, were included in this study. All participants were female patients. All patients
underwent general anaesthesia. Exclusion criteria were unstable haemodynamics (persistent
hypotension preventing extubation at the end of surgery, arrhythmia, ejection fraction
(EF) < 40%), valvular heart disease, cardiac pacing, obesity (BMI >35), chronic
obstructive pulmonary disease (COPD), Increased intrabdominal pressure, open wound at the
US site, preoperative severe hypertension (systolic blood pressure >180 mmHg, diastolic
>110 mmHg), use of angiotensin II receptor blockers (ARB), angiotensin coverting enzyme
inhibitor (ACE-I) and refusal to participate in the study.
Randomization was performed by the sealed envelope method. The closed envelopes were
randomly numbered, and each patient randomly selected the envelope that defined her
group. Those who chose the envelope ending with an even number were identified as group A
patients (n = 55), and those who chose the envelope ending with an odd number were
identified as group B patients (n = 55).
All patients were thoroughly evaluated and medically optimised through the preoperative
preparation outpatient clinic. Intra venous (IV) fluid infusion calculated according to
preoperative weight and dIVC-CI measurement procedure were explained to the patient on
the night of surgery and consent was obtained. Bowel cleansing procedure was performed by
the gynaecological surgeon. Oral nutrition was discontinued at midnight, adhering to the
routine practice of the gynaecology clinic. Group A patients were started on IV infusion
of maintenance fluid (polifleks isolen-s, POLİFARMA İLAÇ SAN. VE TİC. A.Ş.) calculated
according to weight. The maintenance fluid calculated according to weight was 4 mL/st for
the first 10 kg, 2 mL/st for the second 10 kg and 1 mL/st for each remaining kg and
infused hourly during the fasting period.
When the patient reached the operating theatre, the fasting period was questioned and
recorded. 5 lead electrocardiography (ECG), pulse oximetry and non-invasive blood
pressure monitoring (Fabius GS Premium Drager Anesthesia monitor, Germany) were
performed. Masimo Rainbow (Adult/Neonatal Pulse CO-Oximeter Adhesive sensor, CALIFORNIA)
probe was placed on the left index finger of the patients for measurement of PI and PVI
values. Heart rate (HR), SBP, MBP, MBP, PI and PVI baseline measurements were recorded.
IVC ultrasonography was performed after the patient rested in the supine position in
spontaneous respiration for at least 5 minutes before induction. The IVC was imaged in
the paramedian long axis at the junction with the right atrium with a low (3-5 mHz)
frequency convex probe (CA1-7AD Samsung brobu) using USG (Samsung Medison H60, KOREA)
with a subcostal approach. In M mode, respiratory changes in the IVC were evaluated
approximately 1.5-3 cm distal to the right atrium, approximately 2 cm from the point
where the hepatic vein drains into the IVC. The maximum (expiratory) diameter and minimum
(inspiratory) diameter of the IVC were monitored during the same respiratory cycle.
IVC-CI was calculated and recorded as a percentage using the formula IVC-CI = (dIVC
expiration-dIVC inspiration) ×100/dIVC expiration. The patient position and ultrasound
images are shown in Figure 2.
Anesthesia management, 1 mg/kg midazolam and 1 µg/kg fentanyl IV were administered for
sedation. Propofol 2 mg/kg and rocuronium bromide 0.6 mg/kg were used for induction.
Sevoflurane/oxygen/air mixture with a minimum alveolar concentration (MAC) of 0.8-1 was
used for resuscitation. Remifentanil infusion of 0.05-1 µg/kg/min was preferred as
analgesic. Tidal volume was set as 8 ml/kg, frequency 12-16/min, positive end expiratory
pressure (PEEP) 5 cm/H2O. HR (0 st min), SBP (0 st min), MBP (0 st min) measurements were
repeated and recorded. For invasive blood pressure monitoring, an IV cannula was inserted
into the right radial artery under aseptic conditions and PPV (0 st min) was recorded.
HR, SBP, MBP, PI, PVI, PPV measurements were recorded every 10th minute.
After induction, MBP < 60 mmHg or a decrease of more than 30% from basal value was
considered as hypotension. Patients who developed hypotension (Group H) and those who did
not (Group O) were recorded. Group H patients were given 3 ml/kg bolus of infused fluid,
and iv 5 mg ephedrine was administered to patients whose haemodynamics did not improve
despite fluid bolus and recorded. In the intraoperative period, Group A and Group B
patients were administered hourly maintenance fluid (balanced solution) calculated
according to weight, surgical field fluid loss, and crystalloid IV as much as the amount
of diuresis. Erythrocyte replacement was performed in patients with a haemoglobin (Hb)
value of 10 g/dl whose haemodynamics deteriorated due to bleeding.
Anaesthesia was terminated at the end of the surgical procedure. Neuromuscular blockade
was terminated with IV sugammadex. Patients who fulfilled extubation conditions were
transferred to the recovery room after extubation. They were discharged to the ward after
reaching a Modified Aldrete score of 12.
Our primary outcome was a comparison of the incidence of post-induction hypotension
between the two groups. Secondary outcomes included the comparison of dIVC, CI (%), PI,
PVI, and PPV in predicting hypotension.
