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Study on Low Oxygen and Nitrous Oxide Use During Anesthesia for Surgery Patients

Fast replyRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

This clinical trial, known as LOWOX, is focused on patients undergoing surgery under general anesthesia. The study is investigating the effects of using a goal-directed low concentration of oxygen during anesthesia compared to a fixed concentration. The treatment involves the use of a combination of nitrous oxide and oxygen, which are inhaled gases commonly used during surgical procedures to help maintain anesthesia.

The purpose of the study is to determine if adjusting the oxygen levels during surgery can improve the levels of oxygen in the blood after surgery. Participants will be randomly assigned to receive either the goal-directed low oxygen concentration or the routine fixed concentration during their surgery. The study will monitor the participants' recovery, including their oxygen levels, lung function, and overall recovery after surgery.

Throughout the study, various aspects of the participants' health will be assessed, such as their oxygen levels on the second day after surgery and three months later, as well as their recovery from surgery. The study will also look at factors like the length of hospital stay and any infections at the surgical site. The trial aims to provide insights into whether adjusting oxygen levels during surgery can lead to better outcomes for patients.

The research process

The trial runs in 7 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Joining the trial

    Participation begins after providing written consent and meeting the eligibility criteria, which include being an adult over 18 years old, scheduled for abdominal surgery lasting more than 2 hours, and classified under the American Society of Anesthesia (ASA) Class 1-3.

  2. Step 2

    Pre-surgery assessment

    Before surgery, baseline measurements are taken, including arterial oxygen partial pressure (PaO2), diffusion capacity for carbon monoxide, and vital capacity (VC).

  3. Step 3

    Anesthesia administration

    During surgery, anesthesia is administered with a focus on goal-directed low oxygen concentration compared to a fixed oxygen concentration. The inhalation gas used includes a mixture of nitrous oxide and oxygen.

  4. Step 4

    Postoperative day 1

    On the first day after surgery, changes in PaO2 and carbon dioxide partial pressure (PaCO2) are measured and compared to baseline values.

  5. Step 5

    Postoperative day 2

    On the second day after surgery, PaO2 is measured again. If possible, supplemental oxygen is stopped for at least 30 minutes before blood sampling. Changes in diffusion capacity for carbon monoxide and VC are also assessed.

  6. Step 6

    Discharge and recovery

    Upon discharge, postoperative recovery is evaluated using the Postoperative Recovery Profile. The length of hospital stay is recorded.

  7. Step 7

    Follow-up after 3 months

    Three months post-surgery, changes in diffusion capacity for carbon monoxide, VC, PaO2, and PaCO2 are measured again. Surgical site infections and overall recovery are assessed.

Who can join the trial?

4 criteria

  • Must be an adult over 18 years old.
  • Must have given written consent to participate in the trial. This means you agree to join the study and have signed a form to confirm this.
  • Must be scheduled for abdominal surgery that will last more than 2 hours. This includes surgeries related to the stomach area, performed in the Departments of Surgery, Urology, and Gynecology.
  • Must fall under the American Society of Anesthesia (ASA) Class 1-3. This is a way doctors classify patients based on their health before surgery. Class 1 means healthy, Class 2 means mild health issues, and Class 3 means more serious health issues but still stable.

Who cannot join the trial?

3 criteria

  • Patients who are not undergoing surgery under general anesthesia cannot participate. General anesthesia is when you are put into a deep sleep during surgery so you don't feel pain.
  • Patients who are not within the specified age range for the study cannot participate. The study includes certain age groups, but the exact ages are not specified here.
  • Patients who are part of a vulnerable population cannot participate. Vulnerable populations include groups who might need special protection, like children or people with certain disabilities.
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Investigated drugs

Oxygen Therapy is used during anesthesia to maintain adequate oxygen levels in the blood. In this trial, the focus is on comparing two different approaches: a goal-directed low oxygen concentration and a fixed oxygen concentration. The goal-directed approach adjusts the oxygen levels based on the patient's needs, while the fixed concentration provides a constant level of oxygen throughout the procedure. The study aims to determine if the goal-directed method improves postoperative oxygen levels in the blood.

What is already known about the treatment

Oxygen Therapy – Oxygen therapy is administered through inhalation, typically using a mask or nasal cannula, to provide supplemental oxygen to patients. It is widely used in medical settings, especially during surgeries under general anesthesia, to ensure adequate oxygen levels in the blood. The current status of oxygen therapy in medicine is well-established, with extensive literature supporting its use in various clinical scenarios. The main therapeutic indication for oxygen therapy is to treat or prevent hypoxemia, a condition characterized by low levels of oxygen in the blood. At the molecular level, oxygen therapy works by increasing the amount of oxygen available for cellular respiration, which is essential for energy production in cells. It is classified pharmacologically as a medical gas.

Investigated diseases

Surgical Site Infection – This condition occurs when bacteria or other germs enter the body through the surgical incision, leading to infection. It can cause redness, swelling, and pain around the area of the surgery. In some cases, there may be pus or other drainage from the wound. The infection can develop shortly after surgery or even weeks later. It may affect only the skin or go deeper into tissues and organs. Proper wound care and monitoring are essential to prevent and manage this condition.
Trial detailsLast updated 7 Oct 2026
Age18+ yearsPhasePhase ITrial ID2024-513117-12-00Estimated enrolment200 patientsSponsorRegion Vaesterbotten

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