The Measurement of Intraocular Pressure in Normal Children Under General Anesthesia With and Without Nitrous Oxide and Anesthetic Eye Drops
Condition: Glaucoma; Intraocular Pressure; Anesthesia
MeSH terms: Glaucoma
Study type: Interventional
Phase: Early Phase 1

Summary: 
      Pediatric glaucoma is a rare but potentially blinding condition where the pressure in the eye
      is too high. Diagnosis is based on intraocular pressure (IOP) and assessment of the optic
      nerve, cornea and other structures. Accurate intraocular pressure measurements in young
      children is often impossible to obtain in an office setting. Children need sedation or
      general anesthesia to determine IOP. All volatile general anesthetics affect the IOP. Nitrous
      Oxide, a weak volatile anesthetic, does not affect IOP in healthy adults. Since Nitrous Oxide
      has shown to be safe and effective in a variety of practice environments, we want to evaluate
      the use of nitrous oxide in oxygen to obtain IOP measurements in children.
    

Detailed description: 
      The investigator's intention is to measure the IOP under nitrous oxide in Oxygen followed by
      measurements under Sevoflurane in a population of children without glaucoma who are already
      scheduled to undergo general anesthesia for an elective eye surgery. Normally, induction and
      maintenance of general anesthesia in children includes the addition of volatile anesthetics
      such as Sevoflurane. The investigators hypothesize that in children, Nitrous oxide will
      affect IOP from pre-anesthetic baseline minimally. Hence, when sequential IOP measurements
      are taken in short intervals ( every 30 seconds times 3), there will be minimal changes
      during the initial nitrous oxide phase of the induction when compared to the subsequent
      addition of Sevoflurane.

      Subject's parents will be consented and if the subject is old enough to understand the
      procedure, we will have them also sign an assent to the participation of this study.The child
      will be randomized to either the nitrous oxide in oxygen and Sevoflurane group or the Nitrous
      oxide in oxygen alone group or Sevoflurane in oxygen group without Nitrous oxide in the
      inhalational anesthetic mix.

      Subjects will be pre-treated with midazolam via oral administration as a dose of 0.5 - 1
      mg/kg not to exceed 20 mg total. If they present with an intravenous line, they will be
      pre-treated with midazolam at 0.05 - 0.1 mg/kg. All patients receiving preoperative sedation
      will be monitored as per ASA procedural sedation guidelines.

      Once the subject is bought into the operating room, all ASA mandatory vital sign monitors
      will be connected and tetracaine eye drops ( a fast acting topical anesthetic solution) will
      be placed on the subject's right eye. The rapid clearance of this short acting topical
      anesthetic reduces any potential risk for systemic toxicity. Once the drops are in,inhalation
      induction will begin and an initial attempt at measuring IOP will begin when the pediatric
      anesthesiologist deems the patient is ready clinically.all vital signs and IOP Measurements
      will be repeated every 30 seconds three times and recorded for data analysis. Once these
      measurements are recorded, the case will proceed as scheduled and planned.
    

Intervention name(s): Tono-pen XL Applanation tonometer + Ocu-film +
Intervention type(s): Drug
Other intervention name(s): Tono-pen Applanation tonometer, Reichert Technologies
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Diagnostic
Keywords: Pediatric glaucoma; Intraocular pressure; pediatric glaucoma diagnosis; Volatiles and intraocular pressure; nitrous oxide; Tetracaine