Perfusion Index-derived Parameters as Predictors Post-induction Hypotension.

Study Overview
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Brief Summary
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The perfusion index (PI) is a numerical value for the ratio between pulsatile and non-pulsatile blood flow measured by a special pulse oximeter. PI represents the baseline sympathetic tone which is assumed one of the factors contributing for hypotension. Patients with low PI were reported by Mahendale and Rajasekhar to show greater hypotension after induction of anesthesia. This was explained by the high sympathetic tone in these patients which is suddenly masked by propofol administration leading to profound hypotension. This study aims to evaluate the ability of preoperative plethysmographic variability index, perfusion index and the Dicrotic Plethysmography to predict post-induction hypotension.

Detailed Description
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The perfusion index (PI) is a numerical value for the ratio between pulsatile and non-pulsatile blood flow measured by a special pulse oximeter. PI represents the baseline sympathetic tone which is assumed one of the factors contributing for hypotension. Patients with low PI were reported by Mahendale and Rajasekhar to show greater hypotension after induction of anesthesia. This was explained by the high sympathetic tone in these patients which is suddenly masked by propofol administration leading to profound hypotension. Moreover, The PI has been described as a reliable tool for vascular tone assessment and monitoring. Dicrotic Plethysmography (Dicpleth): is easily derived from the photoplethysmographic signal. It represents the relative height of the dicrotic wave compared with the maximum peak of the waveform, has been described as the amount of reflected wave, dependent on the vascular tone. M.Coutrot et al quantified Dicpleth variations to detect arterial hypotension and mentioned that Dicpleth and PI are both related to vascular tone and are easily derived from the photoplethysmographic signal. Moreover, Chowienczyk PJ et. al. demonstrated that the reduction in Dicpleth is related to the reduction of vascular tone caused by vasodilator drugs, such as salbutamol or glyceryl trinitrate

Official Title
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Evaluation of Perfusion Index-derived Parameters as Predictors of Hypotension After Induction of General Anaesthesia: a Prospective Cohort Study.

Conditions
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Hypotension, General Anesthesia Induced Hypotension

Intervention / Treatment
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* Device: Perfusion index derived parameters


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: • Adult patients (18-59 years) ASA I-II 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 peripheral vascular disease or long standing DM affecting PVI readings. Pregnancy.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 59 Years

Sexes Eligible for Study
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All

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| study group<br>adult patients (18-59 years), ASA I-II-III, scheduled for elective surgeries under general anaesthesia. | Device: Perfusion index derived parameters<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). This device allows bluetooth radio for transfer of parameter data to a smart device. The device will be applied on the index finger of the dominant hand of each patient. It will be applied on the hand that neither contains the venous line nor the blood pressure cuff. Three measurements of PVI and PI on one minute interval will be recorded. We will use the average of these readings. Dicpleth is defined as the ratio of the height of the dicrotic notch to the height of the systolic peak, measured at end-expiratory time.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The area under receiver operating characteristic (AUROC) curve for perfusion index to predict hypotension after induction of anesthesia | 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 | 10 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean arterial blood pressure | Mean arterial blood pressure will be measures in supine position in one of the upper limbs in the operating room measured at 1-minute intervals starting from preoperative baseline readings till skin incision. | 15 minutes | 
| Plethysmographic variability index | The area under receiver operating characteristic (AUROC) curve for Plethysmographic variability index to predict hypotension after induction of anesthesia. | 10 minutes | 
| Dicrotic Plethysmography | calculated as a ratio between height of the dicrotic notch to amplitude of the pulsatile component of the digital photoplethysmographic signal. The value will be obtained by averaging the values of three consecutive complexes, at end-expiratory time. The area under receiver operating characteristic (AUROC) curve for Dicrotic Plethysmography to predict hypotension after induction of anesthesia. | 10 minutes | 
| Incidence of post-induction hypotension | defined as mean arterial pressure < 75% of the baseline reading during the period from induction of anesthesia until skin incision. | 15 minutes after induction of anesthesia | 
| Heart rate | preoperative baseline readings | 5 minutes | 
| systolic arterial blood pressure | preoperative baseline readings | 5 minutes | 
| diastolic arterial blood pressure | preoperative baseline readings | 5 minutes |