Inferior Venacava Ultrasound to Guide Fluid Management for Prevention of Hypotension After Spinal Anesthesia.

Study Overview
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Brief Summary
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Hypotension is common during spinal anesthesia and contributes to underperfusion and ischemia. Severe episodes of intraoperative hypotension is an independent risk factor for myocardial infarction, stroke, heart failure, acute kidney injury, prolonged hospital stay and increased one year mortality rates. Empiric fluid preloading can be done to decrease the incidence of hypotension but carries risk of fluid overload especially in elderly and cardiac patients. Inferior venacava ultrasonography (IVC USG) has been used in spontaneously breathing critically ill patients for volume responsiveness but there is limited data regarding its use for volume optimization in perioperative setting. The aim of this study is to evaluate the use of inferior venacava ultrasound to guide fluid management for prevention of hypotension after spinal anesthesia.

Detailed Description
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Introduction: Hypotension is common during spinal anesthesia and contributes to underperfusion and ischemia. It occurs due to reduction in both cardiac output and systemic vascular resistance. Even short duration of intraoperative MAP less than 55 mmHg has been found to be associated with Acute kidney injury (AKI) and myocardial injury. Severe episodes of intraoperative hypotension is an independent risk factor for myocardial infarction, stroke, heart failure, acute kidney injury, prolonged hospital stay and increased 1 year mortality rates. Predictive variables for spinal anesthesia induced hypotension includes peak sensory level, chronic alcohol consumption, emergency surgery, age more than 40 years, hypertension, combined spinal/general anaesthesia(GA), spinal puncture at or above lumbar 2 lumber 3 (L2L3) interspace. Preoperative volume status is an important factor determining patient's hemodynamic status. Traditional static parameters such as central venous pressure have been criticized for invasiveness and lack of accuracy. Newer noninvasive dynamic parameters like inferior venacava diameter and Collapsibility index(CI), acoustic echocardiography, stroke volume variation and pulse pressure variation etc are being used widely for assessing volume status. Study Objective: To evaluate the use of inferior vena cava ultrasound to guide fluid management for prevention of hypotension after spinal anesthesia. Design: A randomized prospective interventional study Sample size: 92 Place: Operating theatres of Tribhuvan University Teaching Hospital (TUTH), Maharajgunj Medical Campus (MMC), Institute of Medicine (IOM). Interventions: A total of 92 patients undergoing lower limb orthopedic surgery will be enrolled in the study. They will be randomized into USG group and Control group. In the USG group, IVC ultrasound will be done and collapsibility index (CI) will be calculated. Depending upon the value of calculated CI, fluid management will be done by infusing Ringer's Lactate (RL). Thereafter spinal anesthesia will be performed. In the control group, spinal anesthesia will be performed without IVC USG assessment. In both the groups, incidence of hypotension and amount of fluid and vasopressors administered will be recorded.

Official Title
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Inferior Venacava Ultrasound to Guide Fluid Management for Prevention of Hypotension After Spinal Anesthesia.

Conditions
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Hypotension, Fluid Overload

Intervention / Treatment
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* Other: Inferior venacava Ultrasonography (IVC USG) guided fluid management


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age ≥16-65 years American Society of Anaesthesiology physical status (ASA PS) I and II Requiring elective spinal anaesthesia for lower limb orthopaedic surgery Exclusion Criteria: Patients with pre-procedural hypotension, defined as two consecutive measurements of systolic arterial pressure (SAP) less than 90 mmHg or mean arterial pressure (MAP) less of 60 mmHg. Contraindication for Spinal Anaesthesia Platelet counts ˂100,000 per microlitre of blood International normalized ratio (INR) ≥1.5 Bleeding disorders Infection at injection site

Ages Eligible for Study
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Minimum Age: 16 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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Control arm<br>Control group will follow the standard procedure in our centre and will not undergo USG assessment before spinal anaesthesia. The spinal anaesthesia procedure will be standardized. Under strict aseptic precautions spinal anesthesia will be performed at L3-L4 inter-space using a 25 Gauge Quincke spinal needle (B. Braun Medical SA, Melsungen, Germany) in sitting position. 3 ml of hyperbaric bupivacaine 0.5% (15 mg) will be injected with the needle orifice oriented cranially. After injection, patients will be immediately positioned supine. Meanwhile, the non-invasive blood pressure will be measured and recorded every 3 minute for 30 min and then every 5 min throughout surgery and anesthesia. | |
| Experimental: USG arm<br>In the IVC USG group, USG assessment and volume optimisation using collapsibility index will be done prior to spinal anaesthesia. all patients will be lying supine, for at least 5 min before IVC examination. Ultrasound measurements will be performed using a Sonosite M-Turbo (Sonosite Inc., USA) machine and phased array 5-1 Megahertz transducer (Sonosite Inc.) set to abdominal mode by an M-mode modality through the subcostal view. All IVC measurements will be performed by principal investigator before spinal anaesthesia. Principal investigator should have performed more than 25 scans before the commencement of the study. | Other: Inferior venacava Ultrasonography (IVC USG) guided fluid management<br>* The IVC will be visualized using a paramedian long-axis view via a subcostal approach. A two-dimensional image of the IVC as it enters the right atrium will be first obtained. Variations in IVC diameter with respiration will be assessed using M-mode imaging performed 2 to 3 cm distal to the junction of right atrium and IVC. Maximum and minimum diameter will be measured from inner wall to inner wall and collapsibility index(CI) will be calculated using formula: CI = [(dIVCmax - dIVCmin)/dIVCmax] x 100% CI of ˃36% will be accepted as predicted fluid responder and ≤36% will be regarded as predicted fluid non responders. Predicted fluid responders will receive a bolus of 500 ml of Ringer's lactate over a time period of 15 min, after which the IVC diameter variation will be reassessed. Additional 250ml of Ringer's lactate bolus will be applied until a non fluid responder pattern is observed during IVC USG. Thereafter,spinal anaesthesia will be performed.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of incidence of hypotension between two groups | To compare the incidence of hypotension after spinal anesthesia between two groups, USG group who have undergone volemic optimization after USG assessment and control group. | 30 minutes after spinal anaesthesia | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Analyse amount of fluids administered between two groups | To compare fluid adjustment requirement between USG group and control group | 30 minutes after spinal anaesthesia | 
| Compare vasopressors used between two groups | To compare the rate of vasopressors used between USG group and control group | 30 minutes after spinal anaesthesia | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Spinal anesthesia, Collapsibility index, Inferior venacava ultrasound, Transthoracic echocardiography