Conventional Fluid Management vs Plethysmographic Variability Index -Based Goal Directed Fluid Management

Study Overview
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Brief Summary
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Plethysmographic variability index is a dynamic method for evaluation of volume status which depends on estimation of respiratory variations in pulse oximeter waveform amplitude. The PVI has been studied in various patient populations and clinical settings, and has been shown to reliably predict fluid responsiveness and guide fluid resuscitation. conventional fluid management. Fluid replacement is managed according to clinical assessment, heart rate, arterial blood pressure and central venous pressure monitoring. However, clinical studies indicate that changes in ABP cannot be used for the monitoring of stroke volume and cardiac output. Another method is the goal-directed fluid management and it is based on individualized fluid management using static and dynamic parameters.

Detailed Description
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This study aims to compare the conventional fluid managment and Plethysmographic Variability index based during elective spine surgeries in prone position. the study hypothesize is: plethysmographic variability index (PVI) based fluid management is more accurate than conventional method in preventing hypovolemia ana hypotension associated with prone position. The patients will be randomly assigned into two equal groups using computer-generated random numbers with closed envelop, each of which will include 33 patients. Group conventional: (n=33) patients are in the conventional fluid management group. Group PVI: (n=33) patients are in the PVI-based goal-directed fluid management group.

Official Title
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Comparison Between Conventional Fluid Management and Plethysmographic Variability Index Based Goal Directed Fluid Management in Patients Undergoing Spine Surgeries in Prone Position; A Randomized Control Trial.

Conditions
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Fluid Management During Elective Spine Surgeries

Intervention / Treatment
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* Procedure: General anaesthesia
* Drug: Conventional fluid managment
* Drug: PVI dependant goal directed fluid therapy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: • Adult patients (18-65 years) ASA I-II Patients scheduled for elective lumbar spine surgeries (e.g.: Lumbar fixation and simple discectomy) under general anaesthesia in prone position. Exclusion Criteria: • Operations which will last for less than 15 minutes. (e.g.: plate and screw adjustment or incomplete terminated surgery) Patients with cardiac morbidities e.g. history of unstable angina, impaired contractility with ejection fraction < 40%, wall motional abnormalities or tight valvular lesions detected by echocardiography, previous cardiac operations or cardiac catherization with stent. Patients with heart block and arrhythmia (atrial fibrillation and frequent ventricular or supraventricular premature beat). Patient with decompensated 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. Complicated surgeries (huge spine tumors, intraoperative vascular or neurological complications and prolonged durations more than 5 hours) or surgeries with massive blood loss (4 units of packed RBCs in 1 hour or replacement of 50% of total blood volume within 3 hours ) Pregnancy.

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

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Group conventional<br> | Procedure: General anaesthesia<br>* All patients in supine position will receive breathing 100% oxygen, induction of anaesthesia will be achieved using propofol (2 mg/Kg), 1-2 mcg/kg of fentanyl and atracurium (0.5 mg/Kg). Endotracheal tube will be inserted after 3 minutes of mask ventilation. Patients who will experience prolonged airway instrumentation due to a difficult intubation will be excluded from further data analysis because of excessive stimulation. Then mechanical ventilation will be performed using a tidal volume of 6-8 mL/kg of ideal body weight at an inspiratory to expiratory ratio of 1:2 without positive end-expiratory pressure. The ventilatory frequency will be adjusted to maintain an end-tidal carbon dioxide tension of 35-40 mmHg. Anaesthesia will be maintained by isoflurane (1-1.5%), atracurium 10 mg intravenous increments every 20 minutes and morphine 0.1 mg/kg intravenous will be given as a long acting analgesia.<br>Drug: Conventional fluid managment<br>* Ringer solution at the dose of 5 ml/kg/h infused throughout the surgical procedure by taking the parameters such as Heart rate (HR), mean arterial pressure (MAP) and urine output, Hypotension was defined as a condition in which the MAP was below 30% of the baseline MAP of the patient. In this case, bolus of 250 ml crystalloids (0.9% NaCl) was given and in case of hypotension persistence, 5 mg I.V. ephedrine administered and repeated every 5 min till the MAP increased over 70% of baseline.<br>|
| Experimental: Group PVI<br> | Procedure: General anaesthesia<br>* All patients in supine position will receive breathing 100% oxygen, induction of anaesthesia will be achieved using propofol (2 mg/Kg), 1-2 mcg/kg of fentanyl and atracurium (0.5 mg/Kg). Endotracheal tube will be inserted after 3 minutes of mask ventilation. Patients who will experience prolonged airway instrumentation due to a difficult intubation will be excluded from further data analysis because of excessive stimulation. Then mechanical ventilation will be performed using a tidal volume of 6-8 mL/kg of ideal body weight at an inspiratory to expiratory ratio of 1:2 without positive end-expiratory pressure. The ventilatory frequency will be adjusted to maintain an end-tidal carbon dioxide tension of 35-40 mmHg. Anaesthesia will be maintained by isoflurane (1-1.5%), atracurium 10 mg intravenous increments every 20 minutes and morphine 0.1 mg/kg intravenous will be given as a long acting analgesia.<br>Drug: PVI dependant goal directed fluid therapy<br>* After the induction of anesthesia, Ringer solution infused at the dose of 2 ml/kg/h started as a basal rate of infusion. If the PVI was higher than 13% for more than 5 min, a 250-ml bolus of crystalloids administrated. If the PVI was still higher than 13% after the bolus, it was repeated every 5 min until the PVI was less than 13% and if MAP was below 30% of the baseline MAP of the patient 5 mg iv ephedrine was applied and repeated every 5 min to keep the MAP increased over 70% of baseline. In the cases where PVI was less than < 13% and if MAP was below 30% of the baseline MAP of the patient 5 mg iv ephedrine was applied and repeated every 5 min to keep the MAP increased over 70% of baseline. Then the patient was turned to prone position and the same steps according to Massimo readings were repeated.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The total intraoperative crystalloid consumption | the total volume of infused crystalloids intraoperatively. | 3 hours | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Plethysmographic variability index | measured every 5 minutes intraoperatively taking in consideration these time points: in supine position in the operating room before induction of anaesthesia as a baseline reading (T0) -postinduction reading (T1) -after prone positioning(T2). Then every 30 minutes all through the operation. | 3 hours | 
| perfusion index | measured every 5 minutes intraoperatively taking in consideration these time points: in supine position in the operating room before induction of anaesthesia as a baseline reading (T0) -postinduction reading (T1) -after prone positioning(T2). Then every 30 minutes all through the operation. | 3 hours | 
| mean arterial blood pressure | measured every 5 minutes intraoperatively taking in consideration these time points: in supine position in the operating room before induction of anaesthesia as a baseline reading (T0) -postinduction reading (T1) -after prone positioning(T2). Then every 30 minutes all through the operation. | 3 hours | 
| Heart rate | measured every 5 minutes intraoperatively taking in consideration these time points: in supine position in the operating room before induction of anaesthesia as a baseline reading (T0) -postinduction reading (T1) -after prone positioning(T2). Then every 30 minutes all through the operation. | 3 hours | 
| Blood lactate level | It will be obtained after induction of anaesthesia (T1) and immediately postoperative in the recovery room (T2). | 3 hours | 
| Total amount of intraoperative urine output | • Oliguria (defined as a condition in which the intraoperative urine output < 0.5ml/kg/hr) will be recorded every hour and treated by boluses of 250 ml crystalloids (0.9% NaCl). | 3 hours | 
| The need and the amount of intraoperative blood transfusion | • The total amount of blood loss will be monitored and if exceed 20% of total blood volume blood transfusion will be started at a dose according to the estimated blood loss. | 3 hours |