Effects of Intubation on Intra-ocular Pressure and Optic Nerve Sheath Diameter
Condition: Intraocular Pressure
Study type: Interventional

Summary: 
      Brief Summary:

      In this study, the investigators aimed to compare the effects of different types of
      endotracheal instruments (Machintosh laryngoscope, McGrath videoingoscope and C-Mac
      videoryngoscope) on intraocular pressure, optic nerve diameter and hemodynamic parameters.
    

Detailed description: 
      Detailed Description:

      Laryngoscopy and endotracheal intubation cause increased intracranial pressure due to
      hypoxia, hypercapnia, straining, or coughing. It may be an indirect result of increased
      arterial and venous pressure, as well as a direct effect of intubation.

      With the emergence of neuroimaging techniques and new diagnostic tools, various methods have
      been developed that can replace invasive methods, which are the gold standard in intraocular
      pressure measurement. However, invasive methods such as intraventricular and intraparenchymal
      catheter systems have some disadvantages and are associated with significant risks in terms
      of infection, bleeding, and time lost until follow-up.

      The intraorbital subarachnoid space surrounding the optic nerve shows the same pressure
      variation as the intracranial subarachnoid space, and any increase in intracranial pressure
      is also seen in the orbital subarachnoid space. With the increase in intracranial pressure,
      the optic nerve, optic nerve sheath diameter, and subarachnoid space enlarge. There are many
      studies reporting that optic nerve sheath diameter can be evaluated using ultrasonography.
      Although there is no clear cut-off value for optic nerve sheath diameter, previous studies
      have found that an optic nerve sheath diameter of 5.0 mm and above may indicate an increase
      in intracranial pressure.

      Previous studies have determined that the distribution of intraocular pressure in the adult
      population varies between 11 mmHg and 21 mmHg, and the mean intraocular pressure is 16.5
      mmHg. It is well known that the sympathoadrenergic response caused by laryngoscopy and
      tracheal intubation significantly increases intraocular pressure (at least 10-20 mmHg). In
      addition, intravenous pressure and intraocular pressure increase due to cough, airway
      obstruction, succinylcholine use, hypoxia and hypercapnia during intubation.

      In this study, the investigators aimed to compare the effects of different types of
      endotracheal instruments (Machintosh laryngoscope, McGrath videoingoscope and C-Mac
      videoringoscope) on intraocular pressure, optic nerve sheath diameter and hemodynamic
      parameters.
    

Intervention name(s): McGrath videolaryngoscopy; C-MAC videolaryngoscopy; Direct laryngoscopy
Intervention type(s): Procedure; Procedure; Device
Intervention description(s): The McGrath video laryngoscope has a thin, disposable, clear, regularly shaped blade similar to a Macintosh blade and a large LCD display attached to the arm. It is lighter in weight and the Mc VL has a small camera at the tip, with a more compact screen and handle that can make tracheal intubation easier and faster in normal or difficult airway. The smaller volume, thinner and portrait screen helps reduce blind spots; The Macintosh blade is attached to the handle and the light beam is passed through the blade tip into a small metal guide tube indented 40 mm. The camera cable is connected to the control unit and the optical cable is connected to the light source. The video macintosh system is installed in a small trolley for easy portability of the device. The trolley supports an 8-inch monitor mounted on a rotating arm on the patient's left side. C-MAC VL devices can create continuous video recordings or static images on a secure removable digital card. The electronic module includes 2 buttons for photo and video shooting. In addition, the image of the C-MAC VL device can be viewed on other devices or recorded via a standard video output port. 3 C-MAC VL reusable metal macintosh blades (sizes 2 to 4) can be used for adult patients. These non-disposable knives have a closed design without gaps in terms of hygiene and have beveled edges to prevent tissue damage.; During intubation with a direct laryngoscope (DL), the laryngoscope is inserted into the oral cavity from the right side of the mouth, the tongue is pushed to the left, and after advancing up to the vallecula, it hangs up and forward. In this way, the floor of the mouth and the epiglottis structure are removed from the field of view. If a straight blade laryngoscope is to be used, it is advanced so that the epiglottis remains under the blade after viewing the epiglottis (1). In DL, manipulations such as head extension, sniffing position, and compression of the cricoid cartilage may be required to facilitate visualization of the vocal folds. In 10-15% of the complications experienced during intubation with DL, there are problems related to the angle of view.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Parallel Assignment Prospective Randomized, Placebo-Controlled Clinical Trial
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: laryngoscope; intraocular pressure; optic nerve sheath