Sedation Methods During Cataract Surgery
Condition: Phacoemulsification; Cataract
MeSH terms: Cataract
Study type: Interventional
Phase: Phase 4

Summary: 
      Background: Phacoemulsification is the most common surgical procedure performed in the United
      States and European Union and sedation is commonly used during phacoemulsification to help
      alleviate patient anxiety and prevent the patient from interfering with the procedure. The
      investigators have administered ketamine in addition to midazolam in this regard. To study
      the effectiveness of this technique, The investigators proposed a study to determine if
      adding low-dose ketamine to midazolam has any beneficial (or negative) effects on operating
      conditions, patient satisfaction, and recovery during and after unilateral
      phacoemulsification procedures performed using topical anesthesia and intravenous (IV)
      conscious sedation.

      Methods: In a free-standing Outpatient Surgery Center, the investigators conducted a
      randomized, double-masked, 3-arm, prospective comparison of IV midazolam only vs. midazolam
      with ketamine 5 mg IV vs. midazolam with ketamine 10 mg IV. The investigators then measured a
      single surgeon's assessment of surgical conditions, self-reported patient satisfaction,
      postoperative pain score, and duration of postoperative stay. The investigators also analyzed
      the dose of midazolam required to meet subjective anxiolysis in each group.
    

Detailed description: 
      Phacoemulsification is the most common surgical procedure performed in the United States and
      European Union. In addition, the number of diagnoses of cataracts is expected to double from
      25,000,000 in 2010 to 50,000,000 in 2050 while the incidence of phacoemulsification is also
      increasing. Therefore, any attempt to optimize outcome and efficiency is significant.

      Sedation is commonly used during phacoemulsification to help alleviate patient anxiety and
      prevent the patient from interfering with the procedure. However, a great deal of variation
      exists in anesthetic management of these cases. Investigators have published use of a number
      of agents for sedation in the literature. These include midazolam, clonidine, propofol,
      fentanyl, dexmedetomidine, remifentanil, and oral diazepam. Intravenous (IV) clonidine has a
      half-life of 9-13 h and increased risk of postoperative hypotension. Propofol causes
      disinhibition and it has to be titrated during surgery to prevent oversedation. Opioids carry
      an increased risk of respiratory depression, prolonged sedation, as well as delirium in the
      elderly. Finally, oral medications do not allow for quick dose adjustments during surgery.

      Intravenous midazolam is commonly used for sedation during phacoemulsification and other
      minor procedures. It has properties as an anxiolytic, muscle relaxant, and it is effective at
      reducing intraocular pressure. However, anxious patients administered benzodiazepines may
      require higher doses during cataract surgery which can lead to oversedation or disinhibition
      with subsequent patient movement. These responses can reduce the patient's ability to follow
      simple commands which can affect surgical outcome. Additionally, patients who receive too
      much sedation may fall asleep and wake up startled, similarly compromising the outcome of the
      surgery.

      In the search for additional medications that can improve surgical conditions and patient
      comfort during phacoemulsification, the investigators explored the use of a medication that
      can improve analgesia and reduce patient movement during procedures, namely ketamine.
      Ketamine is an NMDA antagonist with both sedative and analgesic properties and has minimal
      effects on respiration. Ketamine has been used to premedicate and sedate patients undergoing
      day care procedures without adverse effects, and patients, typically, remain cooperative
      albeit being sedated. These properties along with its relatively short elimination half-life
      of 2 h (compared with 3-4 h for midazolam) make ketamine an attractive agent for sedation
      during monitored anesthesia care (MAC) for cataract surgery.

      The purpose of this study was to determine if adding low-dose ketamine to midazolam has any
      beneficial (or negative) effects on operating conditions, patient satisfaction, and recovery
      during and after unilateral phacoemulsification procedures performed using topical anesthesia
      and IV conscious sedation.

      The investigators measured the surgeon's assessment of the participant's cooperation during
      surgery according to a predetermined Likert scale. The investigators also recorded the
      following outcome measures regarding each participant's surgery: 1) total dose of midazolam,
      2) average time spent in the procedural room, 3) postoperative length of stay (LOS), and 4)
      average postoperative pain score. The subjects received a survey inquiring about the
      subjects' comfort and sedation level during surgery. Finally, the investigators recorded the
      following demographic data for all participants: gender, age, psychiatric diagnoses, and use
      of CNS, psychiatric, or opioid medications.

      Statistical Analysis The investigators used Fisher's exact test for examining data expressed
      as percentages, and Students t-test for yes/no data, and repeated measures ANOVA for 3 group
      analysis (LOS, surgical duration). The investigators judged significance at a P-value of
      0.05. The investigators utilized a generalized estimated equations (GEE) to fit a logistic
      model to assess differences in the responses of patients based on amount of ketamine
      received. The GEE approach can fit models to correlated outcomes, as in the case where
      subjects had more than one procedure performed.
    

Intervention name(s): Midazolam + Ketamine 10 MG/ML: 0.5 ML; Midazolam + Ketamine 10 MG/ML: 1 ML; Midazolam + Normal saline
Intervention type(s): Drug; Drug; Drug
Intervention description(s): 5 mg ketamine IV given just prior to onset of case. Then titrated midazolam up to 2 mg IV at beginning and during case.; 10 mg ketamine IV given just prior to onset of case. Then titrated midazolam up to 2 mg IV at beginning and during case.; Preoperative control: Normal saline placebo given preoperatively. Then protocol followed for titration of midazolam up to 2 mg IV at beginning and during case.
Other intervention name(s): Ketalar; Ketalar; NS
Intervention MeSH terms: Midazolam; Ketamine
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: Randomized, controlled, double-masked, three-armed clinical comparison
Masking: Triple (Participant, Care Provider, Outcomes Assessor)
Primary purpose: Treatment
Keywords: ketamine; midazolam; sedation