Application of Nasal Cannula With Oxygen Versus Air During Eye Surgery Under Local Anaesthetic
Condition: Hypoxia; Hypercapnia
MeSH terms: Hypoxia; Hypercapnia
Study type: Interventional
Phase: Phase 1

Summary: 
      The investigators hypothesize that this new nasal cannula will prevent lack of oxygen as well
      as reduce rebreathing of carbon dioxide under ophthalmic drapes during eye surgery.
    

Detailed description: 
      Surgery involvement the eye has widely been done under local anaesthesia provided by the
      ophthalmologists. Patients are often awake or mildly sedated during the surgery. However, due
      to the surgical drape which covers the patients face and beyond in order to maintain
      sterility of the surgical field, it may lead to hypoxia in these patients and retention of
      exhaled air within the confined space under the drape. This may lead to patient discomfort
      and the surgeon will face difficulty when the patient becomes restless and unable to be still
      for the surgery.

      Various studies had been conducted using nasal cannula with oxygen or air which is
      administered to patients having cataract surgery under local anaesthetics and the results has
      so far been inconclusive.

      One study evaluated the saturation of O2 in arterial blood, the partial pressure of O2 in
      arterial blood (PaO2), the partial pressure of CO2 in arterial blood (PaCO2) and the pH. The
      operative blood gas parameters were maintained in the air inhalation patients. Oxygen
      supplement caused significant increase in the saturation of O2 in arterial blood and in PaO2.
      There was no difference between the two groups in PaCO2. The pH of the arterial blood showed
      a statistically significant decrease in the patients with O2 supplement. This shift to more
      acidotic levels could cause central nervous system depression with reduced respiratory
      stimulus. Recommendation was to administer air rather than O2 to patients during cataract
      surgery.[1]

      Another clinical trials have shown that O2 application by nasal cannula prevents hypoxia but
      not rebreathing of CO2 in patients undergoing eye surgery under local anaesthetics.[4]

      In this clinical trial, we use Duo flow O2 + CO2 sampling cannula designed in a way to
      deliver O2 and sampling of expired CO2 gases from both nostril simultaneously. The aim of
      this study is to randomly administer O2 or air through a new nasal cannula to patients
      undergoing eye surgery under local anaesthetic and to evaluate the significance of O2
      supplement and whether CO2 retention has an indirect effect to it.
    

Intervention name(s): oxygen; oxygen
Intervention type(s): Drug; Drug
Intervention description(s): Subjects who are found to desaturate during treatment with air will be supplement with oxygen; Subjects who are found to desaturate during treatment with air will be supplement with oxygen
Other intervention name(s): resuscitation for hypoxia; resuscitation for hypoxia
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Health Services Research
Keywords: hypoxia or hypercarbia during surgery under the drape