IVC Ultrasonography Versus Plethysmographic Variability Index for Prediction of General Anesthesia Induction Hypotension

Study Overview
=================
Brief Summary
-----------------
This thesis aims to evaluate the ability of preoperative plethysmographic variability index to predict post-induction hypotension in comparison with ultrasound measurements of inferior vena cava (IVC) diameter.

Detailed Description
-----------------
Prospective cohort study. Upon arrival to the operating room, routine monitors (ECG, pulse oximetry, and non-invasive blood pressure monitor) will be applied, intravenous line will be secured and routine premedications (ranitidine 50 mg and ondansteron 4mg) will be administrated. Then inferior vena cava ultrasonography will be performed. Maximum and minimum IVC diameters over a single respiratory cycle will be measured using built-in software. The CI will be calculated as: CI = (dIVCmax - dIVCmin)/dIVCmax , it will be expressed as a percentage. Plethysmographic variability index and a perfusion index readings will be taken preinduction in the form of three readings on one-minute interval. Induction of anaesthesia will be achieved using propofol (2 mg/Kg) and atracurium (0.5 mg/Kg). Endotracheal tube will be inserted after 3 minutes of mask ventilation. Anaesthesia will be maintained by isoflurane (1-1.5%) and atracurium 10 mg increments every 20 minutes. Ringer lactate solution will be infused at a rate of 2 mL/Kg/hour. Any episode of hypotension (defined as mean arterial pressure < 80% of the baseline reading) will be managed by 5mcg norepinephrine.

Official Title
-----------------
Comparison of Ultrasound-based Measures of Inferior Vena Cava and Plethysmographic Variability Index for Prediction of Hypotension During Induction of General Anesthesia; Prospective Cohort Study.

Conditions
-----------------
Hypotension on Induction

Intervention / Treatment
-----------------
* Device: IVC Ultrasonography
* Device: Plethysmographic variability index (PVI) and perfusion index readings (PI)


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Adult patients (>18years) ASA I-II-III Patients scheduled for elective surgeries under general anaesthesia. Exclusion Criteria: Operations which will last for less than 15 minutes. Patients with cardiac morbidities (impaired contractility with ejection fraction < 40% and tight valvular lesions, unstable angina). Patients with heart block and arrhythmia (atrial fibrillation and frequent ventricular or supraventricular premature beat). Patient with decompansted respiratory disease (poor functional capacity, generalized wheezes, peripheral O2 saturation < 90% on room air). Patients with increased intraabdominal pressure (intrabdominal mass compressing IVC). Patients with peripheral vascular disease or long standing DM affecting PVI readings. Pregnancy

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
-----------------
All

Study Plan
=================
How is the study designed?
-----------------

Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| study group<br>Participants will be adult patients (above 18 years), ASA I-II-III, scheduled for elective surgeries under general anesthesia. | Device: IVC Ultrasonography<br>* Ultrasound measurements will be performed using a curved transducer set to abdominal mode (1-5 MHz; Acuson x300; Siemens Healthcare, Seoul, Korea). IVC variation will be assessed using ultrasound in the long-axis (sagittal) view. IVC diameter will be measured 1 cm distal to its junction with hepatic vein either by 2-D or M modes via a subcostal approach according to the methodology described by the American Society of Echocardiography . A two-dimensional image of the IVC as it enters the right atrium will be first obtained.<br>Device: Plethysmographic variability index (PVI) and perfusion index readings (PI)<br>* The PVI and PI will be recorded in the supine position by an anaesthesiologist who was not involved in the further intraoperative monitoring of the patient using Masimo SET (MightySat 9900, Masimo Corporation, Irvine, CA, USA). PVI (%) is a measure of the dynamic change in PI that occurs during one or more complete respiratory cycles, calculated as: PVI= [(PImax-PImin)/PImax] x100<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of the accuracy (Area under receiver operating characteristic curves) of PVI and IVC variation in prediction of post-induction hypotension | Maximum and minimum IVC diameters over a single respiratory cycle will be measured using a built-in software. The CI will be calculated as: CI = (dIVCmax - dIVCmin)/dIVCmax CI will be expressed as a percentage | 10 minutes before general anesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plethysmographic variability index (PVI) and a perfusion index readings (PI) | Three readings, on one-minute interval before general anesthesia induction | 3 minutes | 
| Maximum and minimum IVC diameters | Maximum and minimum IVC diameters over a single respiratory cycle will be measured using built-in software. The CI will be calculated as: CI = (dIVCmax - dIVCmin)/dIVCmax , it will be expressed as a percentage. | 10 minutes | 
| Mean arterial blood pressure | measured at 1-minute intervals starting from the baseline preoperative reading until skin incision as follows: preinduction reading - 1-minute postinduction reading - 2-minute postinduction reading - preintubation reading - one-minute postintubation reading until skin incision | 20 minutes | 
| Heart rate | measured at 1-minute intervals starting from the baseline preoperative reading until skin incision as follows: preinduction reading - 1-minute postinduction reading - 2-minute postinduction reading - preintubation reading - one-minute postintubation reading until skin incision | 20 minutes |