Please select the eligibility criteria that correspond to the clinical trial below.
Title: Measurement of Forces Applied Using a Macintosh Direct Laryngoscope Compared to GlideScope Video Laryngoscope in Patients With at Least One Difficult Intubation Risk Factor
Brief Summary: During Anesthesia many patients require that a breathing be inserted into their windpipe. This is usually achieved using a direct laryngoscope, consisting of a retraction blade with a light near its end. When achieving a direct line-of-sight to the windpipe is difficult, more force is often applied, resulting in greater patient stress. A GlideScope video laryngoscope uses a camera and light source to see the windpipe. This enables the user to see objects that may not be in the direct line-of-sight. This likely results in less force being required, reducing patient stress. Because such stresses are often confounded by patient variables, we are comparing the forces required by the direct and video laryngoscopes on patients with at least one risk factor for difficulty, by directly measuring these with special sensors attached to the laryngoscope blades.


Options:
A: Inclusion Criteria:

The patients who will undergo general anesthesia for abdominal surgery, American Society of Anesthesiologists physical status I to III, The patients who were aged between 20 and 75

Exclusion Criteria:

Our exclusion criteria were to have a history of emergency intubation or a difficult intubation, to have a body mass index higher than 35 or a rheumatologic disease that cause limitation of cervical motion, to have a previous history of cervical operation or tumor, trauma or infection on upper airway, and to have no tooth.
B: Inclusion Criteria:

* After signing of the informed consent,
* ASA physical status I and II
* Mallampati class 1\& 2,
* BMI \< 35,
* Undergoing elective surgical procedures (not exceeding two hours in duration) requiring ET intubation

Exclusion Criteria:

* Patients undergoing day case,
* bariatric, cardiac, nasal, oral or head \& neck surgeries,
* requiring placement of throat pack or nasogastric/ orogastric tube,
* patients assigned to rapid sequence induction,
* hoarseness,
* patients with anticipated difficult intubation,
* history of recent upper respiratory tract infection,
* history of difficult intubation
* psychiatric disorders hindering proper evaluation,
* use of steroids (oral or inhalational) or non-steroidal anti-inflammatory drugs within one week of surgery or previous surgery within last two weeks
C: Inclusion Criteria:

* Patients requiring general anesthesia for orthopedic surgery

Exclusion Criteria:

* known or expected difficult airway
* undergoing urgent or emergent surgery
* non-fasted
* American Society of Anesthesiology Class (ASA) IV-VI
* no consent for participation
D: Inclusion Criteria:

* age \> 18years
* elective surgery
* single lumen endotracheal intubation required
* signed informed consent
* one risk factor for a difficult laryngoscopy ( Mallampati score \>3, inter-incisor gap \< 3.5cm, thyromental distance \< 6.5cm, sternomental distance \< 12.5cm, reduced neck extension and flexion)

Exclusion Criteria:

* lack of patient consent
* anesthesiologist declines to consent
* contraindication to neuromuscular blockade
* ASA 4
* rapid sequence intubation
* previous failed intubation
* other method of intubation indicated eg fiberoptic intubation, awake tracheostomy
* symptomatic gastro-esophageal reflux
* cervical spine instability
* unstable hypertension and symptomatic coronary artery disease
* cerebrovascular disease or raised intracranial pressure
* oral/pharyngeal/laryngeal carcinoma
* loose teeth/poor dentition

Answer: D