Conventional Fluid Management vs Plethysmographic Variability Index -Based Goal Directed Fluid Management
Condition: Fluid Management During Elective Spine Surgeries
Study type: Interventional

Summary: 
      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: 
      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.
    

Intervention name(s): General anaesthesia; Conventional fluid managment; PVI dependant goal directed fluid therapy
Intervention type(s): Procedure; Drug; Drug
Intervention description(s): 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.; 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.; 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.
Intervention MeSH terms: Anesthetics
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Prevention