Appearance anpalpationpalpationpalpationd ultrasound features for predicting difficult laryngoscopy intubation

In the ultrasound group, a linear vascular probe in the frequencies 5 to 13 MHz (GE 12L-RS, GE Healthcare, Chicago, IL, USA) of portable ultrasound device (LOGIQTM, GE Healthcare, Chicago, IL, USA) will be applied to the skin to localize the radial artery and a 20-gauge catheter will be inserted distal to the transducer and directed according to the ultrasound image.

In the HFNC group, preoxygenation will be performed using HFNC (Optiflow™, Fisher & Paykel Healthcare, Auckland, NZ), nasal prongs set at 30 L/min flow of heated and humidified 100% oxygen. In the facemask group, patients will breath spontaneously with an anesthetic facemask and 100% oxygen 15 L/min. Gas flow for HFNC or facemask can be adjusted depending on patients' tolerance. During laryngoscopy intubation, HFNC will be left in place with the nasal flow escalated to 50 L/min of 100% oxygen in order to achieve apneic oxygenation. In the facemask group, the facemask will be removed when apnea occurs.

Patients will be randomized by a computer-generated list into one of the four groups, desflurane with usual care (N=20), desflurane with M-Entropy guidance (N=20), sevoflurane with usual care (N=20), and sevoflurane with M-Entropy guidance (N=20).

Obesity

Anesthesia

Before surgery, ultrasound will be used to assess pretracheal soft tissue depth and height and width of tongue base. The distance from the skin to the anterior aspect of the trachea will be measured at three levels: vocal cords, thyroid isthmus, and suprasternal notch. With the patient in a seated position, the convex transducer of a portable ultrasound device (LOGIQTM, GE Healthcare, Chicago, IL, USA) will be introduced to the skin of the neck in the submental region coronally, immediately cephalad to the body of the hyoid bone, and then in the area between the hyoid bone and the symphysis of the mandible. Maximal width of tongue base, tongue base height, and maximal height of mid-tongue will be measured. The laryngoscopy intubation will be performed using a size‐3 or -4 Macintosh (Rüsch Inc., Duluth, GA, USA) blade and a styletted endotracheal tube. The laryngoscopic view will be graded according to Cormack and Lehane's classification with external laryngeal pressure applied.

Exploring potential risk factors of difficult intubation using ultrasound

For all patients, the wrist will be extended and taped to a board to maintain wrist extension. All patients will receive local skin anesthesia at the anticipated puncture site. All radial artery catheterizations will be performed by anesthesiology residents with similar levels of experience in both blind-palpation and ultrasound-guided radial arterial catheterization. In the ultrasound group, a linear vascular probe of portable ultrasound device (LOGIQTM, GE Healthcare, Chicago, IL, USA) will be applied to the skin to localize the radial artery and a 20-gauge catheter will be inserted distal to the transducer and directed according to the ultrasound image. In the palpation group, the radial artery will be identified by palpation, and the cannula will be directed by continuous or intermittent palpation of arterial pulsation. An attempt is defined as a new penetration of the skin with the needle, followed by an unlimited number of subcutaneous needle redirections.

Radial artery catheterization using ultrasound guidance or blind palpation

In the HFNC group, preoxygenation will be performed using HFNC (Optiflow™, Fisher & Paykel Healthcare, Auckland, NZ), nasal prongs set at 30 L/min flow of heated and humidified 100% oxygen. In the facemask group, patients will breath spontaneously with an anesthetic facemask and 100% oxygen 15 L/min. Gas flow for HFNC or facemask can be adjusted depending on patients' tolerance. During laryngoscopy intubation, HFNC will be left in place with the nasal flow escalated to 50 L/min of 100% oxygen in order to achieve apneic oxygenation. In the facemask group, the facemask will be removed when apnea occurs. After tracheal intubation, correct placement of the endotracheal tube will be confirmed by capnography and the nasal prongs of the HFNC group will be removed.

Comparing the effectiveness of preoxygenation between high-flow nasal cannula and facemask

At the operating room, a M-Entropy™ sensor and S/5™ module (GE Healthcare, Helsinki, Finland) will be applied to all patients' forehead before induction of anesthesia according to the manufacturer's recommendations. Patients will be randomized to Sevoflurane or Desflurane as the single volatile anesthetics for general anesthesia.
Besides, patients will be randomized to M-Entropy group or controls. In the M-Entropy group, dosage of volatile anesthetics will be adjusted to achieve the Response and State Entropy value between 40 and 60 from the start of anesthesia to the end of surgery. In the usual care group, dosage of volatile anesthetics will be titrated according to clinical judgment. M-Entropy monitoring will be continued in the usual care group, but the Entropy number and EEG waveform will be concealed from the anesthetist in charge.

Type of volatile anesthetics and M-Entropy guidance of anesthesia depth

Department of Anesthesiology, Shuang-Ho Hospital, Taipei Medical University

Optimal Anesthesia for Morbidly Obese Patients

An Investigation of Optimal Anesthesia for Morbidly Obese Patients Undergoing Bariatric Surgery: A Randomized Controlled Trial

The laryngoscopic view will be graded according to Cormack and Lehane's classification with external laryngeal pressure applied. Grade 1: Most of the glottis is visible; Grade 2: At best almost half of the glottis is seen, at worst only the posterior tip of the arytenoids is seen; Grade 3: Only the epiglottis is visible; Grade 4: No laryngeal structures are visible.

An attempt is defined as a new penetration of the skin with the needle, followed by an unlimited number of subcutaneous needle redirections.

Arterial blood gas will be analyzed promptly after 5-min preoxygenation.

The interval from discontinuation of volatile anesthetics to spontaneous eye opening

After tracheal intubation, correct placement of the endotracheal tube will be confirmed by capnography.

The interval from the finger or ultrasound probe touching the skin to successful arterial catheterization

Including pain, ultrasound-measured hematoma, arterial vasospasm, and arterial occlusion.

Arterial blood gas will be analyzed twice before and after preoxygenation

Measured by 10-point Likert scale, 0 minimal comfort and 10 maximal comfort

The interval from discontinuation of volatile anesthetics to tracheal extubation

The interval from discontinuation of volatile anesthetics to orientation in time and place

The interval from discontinuation of volatile anesthetics to leaving operating room

Measured by Richmond Agitation-Sedation Scale, classifying into combative, very agitated, agitated, restless, alter and calm, and drowsy

prognathism/kašalj

Optimal Anesthesia for Morbidly Obese Patients

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