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

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.

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.

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.

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.