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NCT Number: NCT05550181

Intraoperative Hypocapnia in PROVHILO and PROBESE

To gain a better understanding of the epidemiology of intraoperative hypocapnia, in particular the associations of intraoperative hypocapnia with patient demographics, ventilator characteristics, and perioperative complications we will perform an individual patient-level meta-analysis of two recent randomized clinical trials of intraoperative ventilation, the 'PROtective Ventilation using High versus LOw PEEP trial' (PROVHILO), and the 'Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients trial' (PROBESE).

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Key information

Conditions

Mechanical Ventilation Complication Hypocapnia Intraoperative Complications Pathologic Processes Pathological Conditions, Signs and Symptoms Postoperative Complications Pulmonary Complication Signs and Symptoms Signs and Symptoms, Respiratory Surgery

Age range

18 year and older

Sex eligibility

All sexes

Study type

Observational

Primary location

Hospital Israelita Albert Einstein, São Paulo, Brazil

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About this study

Lung-protective intraoperative ventilation (LPV) has the potential to improve the outcome of surgery patients through a reduction in postoperative pulmonary complications. Use of intraoperative ventilation strategies that use a low tidal volume could result in intraoperative hypercapnia. However, hypocapnia remains surprisingly common during intraoperative ventilation, possibly meaning that anesthesiologists continue to use high, if not too high respiratory rates or tidal volumes.

Previous studies suggested associations between intraoperative derangement of end-tidal carbon dioxide (etCO2) and postoperative outcomes. Indeed, two studies in highly selected patient groups showed associations of intraoperative hypocapnia with prolonged length of hospital stay, in patients undergoing pancreaticoduodenectomy, and in patients undergoing hysterectomy.

To gain a better understanding of the epidemiology of intraoperative hypocapnia, in particular the associations of intraoperative hypocapnia with patient demographics, ventilator characteristics, and perioperative complications we will perform an individual patient-level meta-analysis of two recent randomized clinical trials of intraoperative ventilation; PROVHILO and PROBESE.

Who can participate

Healthy volunteers accepted: No

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

Inclusion criteria

  • Planned for major (abdominal) surgery.
  • At risk for postoperative pulmonary complications.

Exclusion criteria

  • Planned thoracic surgery or neurosurgery.
  • Unscheduled surgery (i.e., urgent, or emergent surgeries) were excluded because these patients may have had metabolic abnormalities at the moment of surgery, i.e., metabolic acidosis, for which the anesthesiologist may have adjusted the intraoperative ventilator settings. This may have led to a 'compensatory' low etCO2.
  • Patients with etCO2 recordings are missing from the study databases.

Treatment and study plan

intraoperative mechanical ventilation with hypocapnia (etCO2 < 35 mm Hg)

Behavioral

A patient is considered 'hypocapnic' if the etCO2 was < 35 mm Hg at any point during surgery, from start of the study till end of the study and classified as 'without hypocapnia' otherwise. In case of a missing value immediately before extubation, we will use the values as reported in the last hour of surgery.

Primary outcomes

  1. Incidence of postoperative pulmonary complications

    Time frame: Until day seven or hospital discharge, whichever comes first

    Composite of predefined and collected postoperative pulmonary complications. Postoperative pulmonary complications included mild, moderate, and severe respiratory failure; acute respiratory distress syndrome; bronchospasm; new pulmonary infiltrate; pulmonary infection; aspiration pneumonitis; pleural effusions; atelectasis; cardiopulmonary edema; and pneumothorax.

Secondary outcomes

  1. Incidence of intraoperative complications

    Time frame: Intraoperatively

    Defined as intraoperative hypotension, arrhythmias; or need for rescue for desaturations; or need for vasoactive drugs.

  2. Incidence of intensive care unit admission

    Time frame: Until hospital discharge, death or 100 days, whichever comes first

    Incidence of intensive care unit admission during hospital stay

  3. Incidence of extrapulmonary pulmonary complications

    Time frame: Until day seven or hospital discharge, whichever comes first

  4. Incidence of 7-day mortality

    Time frame: Mortality during the first seven days of hospitalization

    Until day seven or hospital discharge, whichever comes first

  5. Incidence of in-hospital mortality

    Time frame: From date of randomization until the date of first documented progression or date of death from any cause, whichever came first, assessed up to 100 days

  6. Incidence of major postoperative complications

    Time frame: Until day seven or hospital discharge, whichever comes first

    Collapsed composite of complications developing within the first seven postoperative combining severe postoperative pulmonary complications, sepsis, septic shock and/or acute kidney injury

Sponsors and collaborators

Lead sponsor

NMC Specialty Hospital

Other

Collaborators

  • Academisch Medisch Centrum - Universiteit van Amsterdam (AMC-UvA)
  • Hospital Clínico Universitario de Valencia
  • Hospital Israelita Albert Einstein
  • University Hospital Carl Gustav Carus

Registry information

Official study title

Associations of Intraoperative Hypocapnia With Patient Demographics, Ventilation Characteristics and Outcomes--Statistical Analysis Plan for an Individual Patient Data Analysis of PROVHILO and PROBESE

Acronym: iHypoPRO

Important dates

Study start
2022
Primary completion
2023
Study completion
2023
First posted
Sep 22, 2022
Registry last updated
May 6, 2023

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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