Comparing Endotracheal Tube Cuff Pressure in Laparoscopic Abdominal Surgery: Saline vs. Air Inflation
Condition: Endotracheal Intubation
Study type: Interventional

Summary: 
      In this study, the investigators aim to compare the incidence of cuff pressure increase
      between endotracheal tubes inflated with air or saline during elective laparoscopic abdominal
      surgery under general anesthesia with N2O. This prospective observational study will be
      conducted on 60 patients aged 18-65 with ASA physical status I-II undergoing elective
      laparoscopic abdominal surgery under general anesthesia. Patients are randomly assigned to
      two groups: one group has tubes inflated with air (Group H, n=30), while the other group has
      tubes inflated with saline (Group S, n=30). The cuff pressure is continuously monitored using
      a pressure transducer attached to the cuff via a three-way tap. Anesthesia maintenance is
      achieved with sevoflurane and oxygen/N2O (%40/%60) in both groups. The intervention is
      performed whenever the cuff pressure exceeds 20 mmHg for >30 seconds during the CO2
      insufflation of the abdomen, and the pressure is reduced. The number of interventions is
      recorded as the primary outcome of the study. The cuff pressure is measured before and after
      insufflation and after the patients are placed in Trendelenburg and reverse Trendelenburg
      positions.
    

Detailed description: 
      The study is designed as prospective and observational research, which takes place at the
      Balcalı Hospital of Çukurova University between July 2023 and October 2023. After obtaining
      written informed consent from the participants and approval from the Çukurova University
      Clinical Research Ethics Committee (Date: 13.07.2023 and Decision no: 186/10), a total of 60
      patients, aged between 18-65, with ASA 1-2 risk category, and expected surgical duration of
      30-120 minutes, are included in the study for elective laparoscopic abdominal surgery. The
      exclusion criteria include neuropsychiatric diseases, muscle diseases, significant
      cardiovascular and respiratory system diseases, upper respiratory tract infection within the
      past 14 days, morbid obesity, alcohol or substance dependence, history of bronchospasm,
      expected difficult intubation, history of tracheostomy, and laryngeal diseases or surgery.
      After informing the patients about the procedure and obtaining written consent, intravenous
      (IV) access is established in the preoperative preparation room after an 8-hour fasting
      period. No premedication is administered. Once the patients are transferred to the operating
      room, standard anesthesia monitoring including electrocardiography (ECG), non-invasive blood
      pressure, peripheral oxygen saturation (SpO2), and end-tidal CO2 (EtCO2) are applied.
      Following 3 minutes of preoxygenation with 100% oxygen, anesthesia induction is performed
      with a 2 mg/kg IV propofol. TOF (train-of-four) monitor calibration is performed to assess
      the level of muscle relaxation. Subsequently, 0.6 mg/kg of rocuronium IV is administered for
      neuromuscular blockade. Fentanyl 1 mcg/kg IV is given during anesthesia induction.
      Endotracheal intubation (ETI) is performed using a high-volume, low-pressure cuffed
      endotracheal tube (ETT) with an internal diameter of 7-7.5 mm for female patients and 8-8.5
      mm for male patients, once the TOF measurement reaches 0. The intubation procedure is carried
      out by an experienced anesthesiologist using a Macintosh laryngoscope. According to the
      randomization table created with a computer program, patients who are randomly selected after
      endotracheal intubation have the APL valve of the anesthesia machine adjusted to a pressure
      of 20 cmH20, ensuring that there is no air leakage sound from the patient's mouth during
      ventilation. The ETT cuffs of patients in Group H are inflated with air, while those in Group
      S are inflated with saline. The cuff pressure is continuously monitored using a pressure
      transducer connected to the cuff balloon through a three-way stopcock. The transducer set is
      filled with saline to ensure no air is present. It is connected to a three-way stopcock at
      the desired measurement point level. All connections are taped to prevent disconnection and
      leaks, and a "For Respiratory Use Only" label is affixed to enhance patient safety. The
      pressure calibration on the patient monitor is adjusted according to the sternal notch level
      of the patient, and the cuff pressure value is measured in mmHg. After ETT placement,
      ventilation of the patient is set as volume-controlled ventilation with a tidal volume of 6-8
      ml/kg, frequency of 10-12/min, and EtCO2 of 35-45 mmHg. An esophageal temperature measurement
      probe is placed to monitor body temperature. Maintenance of anesthesia for all patients is
      achieved using a gas mixture of sevoflurane and oxygen/nitrous oxide (40%/60%). When the TOF
      value is 2 during the maintenance of muscle relaxation, rocuronium 0.15 mg/kg is administered
      intravenously. Nasogastric tubes are placed in all patients. 45 minutes before the completion
      of the surgery, tramadol 2 mg/kg IV and paracetamol 1 g IV are administered to provide
      postoperative analgesia. In cases where the intracuff pressure exceeds 20 mmHg for more than
      30 seconds during CO2 insufflation, intervention is performed using a three-way stopcock and
      syringe to reduce the pressure to 18 mmHg, and the number of interventions is recorded. The
      highest intracuff pressure, ventilator peak pressure, plateau pressure, and PEEP are recorded
      every 15 minutes during the first minute after CO2 insufflation. In cases where the intracuff
      pressure exceeds 20 mmHg for more than 30 seconds during this period, intervention is
      performed to reduce the pressure to 18 mmHg using a three-way stopcock and syringe. The
      number of interventions is recorded. Additionally, the intracuff pressures before and after
      the patients are placed in the reverse Trendelenburg and Trendelenburg positions are
      recorded. At the end of the surgery, 0.04 mg/kg neostigmine IV and 0.01 mg/kg atropine IV are
      administered to reverse the effects of muscle relaxation. The patients are extubated when
      they respond adequately to verbal stimuli and the train-of-four (TOF) value is 90% or above.
      Once sufficient muscle strength and airway safety are ensured, the patients are transferred
      from the operating room to the postoperative recovery unit.

      In our pilot study, we observed that the total number of interventions 30 minutes after
      insufflation differed significantly between the saline group (mean = 2.31) and the air group
      (mean = 4.01), with a standard deviation of 1.68. To ensure a 95% power and a significance
      level of 0.05%, we determined that a sample size of 27 patients per group (total of 57
      patients) was necessary. To account for potential data loss, we included 60 patients in the
      study.
    

Intervention name(s): Endotracheal intubation using an endotracheal tube with cuff inflated with air; Endotracheal intubation using an endotracheal tube with cuff inflated with saline
Intervention type(s): Procedure; Procedure
Intervention description(s): After endotracheal intubation, the endotracheal tube cuff is inflated with air; After endotracheal intubation, the endotracheal tube cuff is inflated with saline
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Prospective randomized controlled study
Masking: Single (Participant)
Primary purpose: Treatment