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NCT Number: NCT05171608

Preoperative Ultrasound-based Protocol for Optimization of Fluid Therapy to Prevent Early Intraoperative Hypotension

Background: Intraoperative hypotension increases 30-day mortality and the risks of myocardial injury and acute renal failure. Patients with inadequate volume reserve before the induction of anesthesia are highly exposed. The identification of latent hypovolemia is therefore crucial. Ultrasonographic measurement of the inferior vena cava collapsibility index (IVCCI) is able to detect volume responsiveness in circulatory shock and growing evidence support the theory that higher IVCCI can predict intraoperative hypotension.

The aim of the present study is to evaluate the potential benefit of an ultrasound-based protocol for preoperative fluid optimization. The investigators will perform a randomized-controlled study involving elective surgical patients. An ultrasound-based protocol (USP) arm and a conventional fluid therapy group (CFT) are to be formed. Ultrasound examinations will be performed twice in both groups: 2 hours and 30 minutes preoperatively. The inferior vena cava and the anterior lung fields will be scanned. In the USP group the participants will receive fluid therapy according to the ultrasonographic findings: high level of IVCCI and absence of signs of pulmonary edema will indicate fluid therapy. In the CFT group the attending anesthesiologist (blinded to the results of ultrasonography) will order fluid therapy on the basis of daily routine and clinical judgement.

The investigators will evaluate the incidence of intraoperative hypotension (primary outcome), postoperative metabolic status and organ functions and the amount of the administered intravenous fluids in both groups.

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Key information

Conditions

Anesthesia Cardiovascular Diseases Echocardiography Hypotension Lung Ultrasound Perioperative Complication Vascular Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Semmelweis University, Deparment of Surgery, Transplantation and Gastroenterology

Budapest, 1082, Hungary

About this study

A randomized-controlled study with 80 participants.

The investigators will use computer-generated unpaired random allocation method to an ultrasound-based protocol (USP) group or to the conventional fluid therapy (CFT) group.

Preoperative ultrasound examinations will be performed twice in both groups: 2 hours and 30 minutes preoperatively. The inferior vena cava and the lung fields (so called BLUE - Bedside Lung Ultrasound in Emergency - points: 2nd or 3rd intercostal space anterior, 5th-6th interspace anterior and posterior axillary line position) will be scanned. The collapsibility index (IVCCI) of the IVC is calculated, >40 percent is considered 'high IVCCI'. Lung ultrasound (LUS) is evaluated as indicative for 'lung congestion' if symmetric anterior B-profiles (at least 3 B-lines in anterior lung fields) are detected.

Baseline demographic (age, sex, height, weight) and comorbidity data (history of hypertension, chronic heart failure, coronary or cerebrovascular disease, respiratory illness e.g. COPD, past COVID, diabetes on insulin treatment) together with laboratory data (haemoglobin, creatinine, blood urea) are to be recorded.

A standardized practice of monitoring and induction of general anesthesia will allow for the detection of immediate and early (first 10 minutes of anesthesia) hypotensive events. A follow up for 24 hours is necessary for evaluating the fulfillment of secondary endpoints. A semi-quantitative lung ultrasound after 24 hours will estimate lung aeration.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Elective surgery

  • General surgical procedures
  • Estimated duration of anesthesia > 60 minutes
  • ASA class 2 or 3

Exclusion criteria

  • Emergency procedure
  • Reoperation, redo procedure
  • Patient who is incapable of acting
  • Uncontrolled hypotension (<90 mmHg)
  • Uncontrolled hypertension (>180 mmHg)
  • High risk valvular disease (Aortic Stenosis)
  • Endocrine hypertension (Conn's syndrome, phaeochromocytoma)
  • Sepsis (infection and SOFA≥2 pt)
  • Conditions blocking lung ultrasound (pneumothorax without drainage, former pulmonary resection, pleural effusion affecting more than 2 interspaces)
  • Pregnancy

Treatment and study plan

Ultrasound-based protocol based fluid therapy

Procedure

Protocol of the interventional group according to the ultrasonographic findings:

Ultrasound scan 2 hours before surgery:

IVCCI>40 percent and absence of symmetric anterior 'B-profile' on the lung ultrasound indicate intravenous (IV) fluid therapy: 8 ml/kg of isotonic, balanced crystalloid infusion.

IVCCI≤40 percent AND/OR symmetric anterior 'B-profile' contraindicates further IV fluid therapy.

A 2nd ultrasound scan at 30 minutes before surgery:

IVCCI>40 percent and absence of symmetric anterior 'B-profile' on the lung ultrasound indicate further IV fluid therapy: 5 ml/kg of isotonic, balanced crystalloid infusion.

IVCCI≤40 percent AND/OR symmetric anterior 'B-profile' contraindicates further IV fluid therapy.

Primary outcomes

  1. Rate of hypotension associated to general anesthesia induction

    Time frame: first 10 minutes of anesthesia

    mean arterial pressure < 65 mmHg AND/OR ≥30 percent of decrease compared to baseline (before induction of anesthesia)

Secondary outcomes

  1. Dose of preoperative fluid therapy (in millilitres)

    Time frame: preoperative time frame on the day of surgery

    intravenous fluid therapy before anesthesia induction

  2. Dose fluid therapy of the operative day (in millilitres)

    Time frame: 24 hours

    all intravenous fluid therapy on the day of surgery

  3. lactate level (mmol/l)

    Time frame: 1st postoperative hour

    highest lactate level in mmol of an arterial blood sample

  4. base excess (mmol/l)

    Time frame: 1st postoperative hour

    worst base excess level in mmol of an arterial blood sample

  5. urine output (millilitres/24 h)

    Time frame: 24 hours

    summarized urine output after surgery

  6. lung ultrasound score (LUS)

    Time frame: 24th postoperative hour

    Summarized lung ultrasound score of 12 fields of the thorax (0-36 pts)

Sponsors and collaborators

Lead sponsor

Semmelweis University

Other

Registry information

Official study title

Preoperative Ultrasound-based Protocol for Optimization of Fluid Therapy to Prevent Hypotension Associated to General Anesthesia: a Randomized Controlled Trial

Important dates

Study start
2021
Primary completion
2022
Study completion
2022
First posted
Dec 29, 2021
Registry last updated
Sep 7, 2022

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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