How Safe is Minimal Flow Anesthesia in Terms of Infection?
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 入组人数
- 140
- 试验地点
- 2
- 主要终点
- Assessment of Bacterial Contamination in Anesthesia Circuits and Nasopharyngeal Swab Samples
研究概览
简要总结
This study is being done to find out if the heat and moisture that build up during minimal flow anesthesia can lead to the growth of germs (microorganisms) inside the anesthesia equipment. Minimal flow anesthesia (using fresh gas flow of 0.5 liters per minute or less) is known to help protect the lungs and the environment. However, it may also cause water to collect in the equipment, which could allow germs to grow. In this study, we want to see whether this type of anesthesia is safe when it comes to the risk of germs in the equipment.
详细描述
Introduction Inhalation anesthesia is commonly administered using fresh gas flows between 2-6 L/min (liters per minute ). When this flow is reduced to 1 L/min, it is referred to as low-flow anesthesia, and when set at 0.5 L/min, it is known as minimal-flow anesthesia. The high-flow technique maintains a continuous supply of fresh gas within the system. However, since the patient inhales only a small portion of this gas, the majority is expelled into the anesthetic gas scavenging system. While this approach enables rapid adjustment of gas concentrations (O₂, anesthetic agents), the gases within the circuit remain cold and dry due to the removal of heat and humidity from the patient's lungs by soda lime. Additionally, a considerable amount of anesthetic gas is wasted.
In contrast, using fresh gas flows of ≤1 L/min decreases the amount of gas delivered from the vaporizers to the breathing circuit. This results in slower changes in gas concentrations but offers important advantages. Low-flow and minimal-flow anesthesia humidify and warm the inspired gases, which protect the patient's lungs. Compared to cold, dry gases, this improves mucociliary clearance, reduces damage to the respiratory epithelium, and lowers the release of inflammatory mediators. Low-flow anesthesia is a safe and effective practice that benefits patients and also provides economic and environmental advantages.
Minimal-flow anesthesia helps reduce heat loss through the respiratory tract and prevents the drying of mucosal surfaces, both of which are more common with higher flow rates. Additionally, it significantly decreases the amount of wasted fresh gas and inhaled anesthetic released into the atmosphere. Together, these effects may result in reduced airway inflammation and infection, lower environmental emissions, and cost savings.
Modern anesthesia machines support the safe delivery of low-flow anesthesia by utilizing closed breathing circuits that minimize leaks, manage humidity, ensure accurate gas delivery, and provide advanced monitoring and ventilator technologies.
Study Objective The primary objective of this study is to determine whether the increased humidity and temperature generated during minimal-flow anesthesia contribute to microbial colonization in the anesthesia circuit.
研究设计
- 研究类型
- Interventional
- 分配方式
- Randomized
- 干预模型
- Parallel
- 主要目的
- Other
- 盲法
- Triple (Participant, Investigator, Outcomes Assessor)
入排标准
- 年龄范围
- 18 Years 至 65 Years（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •A total of 140 voluntary patients will be included in the study.
- •Patients will be aged between 18 and 65 years.
- •Both male and female patients will be enrolled.
- •All patients will be classified as c physical status I or II.
- •Patients will undergo elective surgical procedures.
- •The study will be conducted in the operating rooms of Ankara Bilkent City Hospital, affiliated with the Ministry of Health of the Republic of Türkiye.
排除标准
- •Patients who do not consent to participate
- •Patients outside the age range of 18-65 years
- •Patients classified as ASA (American Society of Anesthesiologists) III, IV, or V
- •Patients scheduled for emergency surgery
- •Patients with uncontrolled hypertension
- •Patients with significant cardiac diseases (e.g., heart failure, coronary artery disease, arrhythmia, valvular heart disease)
- •Patients with significant pulmonary diseases (e.g., Chronic Obstructive Pulmonary Disease, Restrictive Pulmonary Disease, Asthma)
- •Patients with neuromuscular disorders
- •Patients with poorly controlled diabetes mellitus
- •Patients with metabolic disorders
- •Patients with immunodeficiency
- •Patients with significant anemia
- •Patients with bleeding diathesis
- •Patients with liver and/or kidney diseases
- •History of cardiac surgery
- •History of intracranial surgery
- •History of pulmonary surgery
- •History of head and neck surgery
- •Anticipated difficult airway or difficult intubation
- •Patients with alcohol or drug dependence
- •Pregnant or lactating women
- •Known allergy to anesthetic agents
- •Body mass index (BMI) > 30 kg/m²
- •Presence of sepsis or active infection
- •Baseline body temperature < 35°C or > 38°C
- •Patients who have received antibiotics in the past month
- •Patients with malignancies
- •Withdrawal Criteria Patients who develop hemodynamic instability during the intraoperative period
- •Patients requiring interruption of minimal flow anesthesia for more than 5 minutes
- •Patients whose anesthesia circuit becomes disconnected intraoperatively
研究组 & 干预措施
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Propofol 1% (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Propofol 1% (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Lidocaine %2 ampoule (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Ephedrine Hydrochloride 0,05 mg/ml ampoule (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Atropine Sulphate 0.5mg/ml ampoule (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Sugammadex 200 MG in 2 ML Injection (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Sevoflurane (Volatile Anesthetic) (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Remifentanil 2 MG (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Minimal-Flow Anesthesia (Procedure)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Anesthesia Circuit Sampling (Diagnostic Test)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Body Temperature Monitoring (Procedure)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Nasopharyngeal Swab Collection (Diagnostic Test)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Rocuronium 50 mg/5 ml (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Lidocaine %2 ampoule (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Ephedrine Hydrochloride 0,05 mg/ml ampoule (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Fentanyl (IV) (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Atropine Sulphate 0.5mg/ml ampoule (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Peripheral Intravenous Cannulation (Procedure)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Mechanical Ventilation (Procedure)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Crystalloid solutions (Drug)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Endotracheal Intubation (Procedure)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: American Society of Anesthesiologists (ASA) Standard Monitors (Procedure)
Minimal Flow Anesthesia (0.5 L/min)
Participants in this group will receive minimal-flow inhalation anesthesia, administered at a fresh gas flow rate of 0.5 L/min (Liters per minute). This technique helps preserve heat and humidity within the anesthesia circuit while reducing both anesthetic gas waste and environmental impact. The study aims to evaluate whether this lower flow rate contributes to circuit condensation and microbial colonization in the breathing system.
干预措施: Microbiological Culture and Identification (Diagnostic Test)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Rocuronium 50 mg/5 ml (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Remifentanil 2 MG (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Sugammadex 200 MG in 2 ML Injection (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Peripheral Intravenous Cannulation (Procedure)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Mechanical Ventilation (Procedure)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Crystalloid solutions (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Endotracheal Intubation (Procedure)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: American Society of Anesthesiologists (ASA) Standard Monitors (Procedure)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Normal-Flow Anesthesia (Procedure)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Anesthesia Circuit Sampling (Diagnostic Test)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Body Temperature Monitoring (Procedure)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Nasopharyngeal Swab Collection (Diagnostic Test)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Microbiological Culture and Identification (Diagnostic Test)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Sevoflurane (Volatile Anesthetic) (Drug)
Standard Flow Anesthesia (2 L/min)
Participants in this group will receive inhalation anesthesia with a continuous fresh gas flow rate of 2 liters per minute (L/min) throughout the surgical procedure. This represents conventional-flow anesthesia, in which higher gas turnover allows for rapid adjustments in anesthetic concentrations but may lead to increased loss of heat and humidity within the breathing circuit.
干预措施: Fentanyl (IV) (Drug)
结局指标
主要结局
Assessment of Bacterial Contamination in Anesthesia Circuits and Nasopharyngeal Swab Samples
时间窗: During the observational period, which begins 10 minutes prior to anesthesia induction and continues until 10 minutes after the cessation of anesthesia.
The aim of this study is to evaluate and compare bacterial contamination in the inspiratory and expiratory limbs of anesthesia circuits and in the nasopharyngeal region of patients undergoing elective surgery under either minimal-flow (0.5 L/min) or normal-flow (2 L/min) inhalation anesthesia. A total of four sterile swab samples will be collected from each patient: one nasopharyngeal swab upon arrival to the operating room, and three circuit swabs-two taken from the inspiratory and expiratory limbs before circuit connection, and one after circuit disconnection at the end of the procedure. All samples will be cultured and incubated under appropriate conditions, and microbial identification will be performed to the species level using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).
次要结局
- End-Tidal Carbon Dioxide (ETCO₂) Levels at Defined Perioperative Time Points (mmHg)(From 10 minutes before induction to 45 minutes after anesthesia termination)
- Changes in Body Temperature During Anesthesia(From 10 minutes before induction to 45 minutes after anesthesia termination)
- Mean Arterial Pressure at Defined Perioperative Time Points (mmHg)(From 10 minutes before induction to 45 minutes after anesthesia termination)
- Heart Rate at Defined Perioperative Time Points (bpm)(From 10 minutes before induction to 45 minutes after anesthesia termination)
- Peripheral Oxygen Saturation (SpO₂) at Defined Perioperative Time Points (%)(From 10 minutes before induction to 45 minutes after anesthesia termination)
研究者
Aysun ERŞEN YÜNGÜL
Specialist Physician
Ankara City Hospital Bilkent