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

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.

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.

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.

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