Respiratory Function of Dexmedetomidine in Patients Undergoing Pleuroscopy
Condition: Pleural Effusions, Chronic; Pleural Effusion, Malignant; Pleural Diseases
MeSH terms: Pleural Effusion, Malignant; Pleural Effusion; Pleural Diseases
Study type: Observational

Summary: 
      The primary objective of this prospective trial will be to assess the effects of
      dexmedetomidine administration on oxygenation and respiratory function in patients undergoing
      diagnostic or therapeutic medical thoracoscopy/pleuroscopy for a pleural effusion compared to
      conventional conscious sedation/monitored anesthesia care (MAC) with midazolam. The secondary
      endpoint of the study will be to also assess the effects of dexmedetomidine administration on
      respiratory mechanics and postprocedural complications
    

Detailed description: 
      The study will be conducted at the Department of Anesthesiology and Pain Management in
      collaboration with the Department of Thoracic Surgery at the Attikon University Hospital,
      Athens.

      The trial has received approval by the Attikon University Hospital's Scientific & Bioethics
      Committee and written informed consent will be obtained from all patients enrolled in the
      study.

      Sample Size Calculation: A total of 60 patients will be assigned on a 1 to 1 basis to avoid
      bias to either a "DEX = dexmedetomidine" (n=30) or a "MIDAZOLAM/FENTANYL" group (n=30). To
      determine the required sample sizes quoted above, the statistical G-power calculator
      developed by Faul, Erdfelder, Lang, and Buchner was used. Values used to calculate the effect
      size (e=0.9326031) are based on results previously reported in the literature. For a study
      power of 90% with an alpha value of 0.05, a total of 26 patients in each group will need to
      be enrolled. Factoring in possible losses this number was rounded up to 30 patients per
      group.

      Main Measurements Performance & Methods: Patients will initially be assessed with spirometry
      and arterial blood gas (ABG) analysis prior to the medical thoracoscopy/pleuroscopy to
      determine their baseline values of Forced Expiratory Volume in 1 second (FEV1), Forced Vital
      Capacity (FVC) and Partial arterial Pressure of Oxygen/ Fraction of Inspiratory Oxygen
      (PaO2/FiO2) ratio respectively. Intra-operatively repeat ABG analysis will be performed at 30
      minutes following the start of administration of the study drug. Subsequent to their medical
      thoracoscopy/pleuroscopy procedure study subjects will remain in the Post Anesthesia Care
      Unit (PACU) for a minimum of 1 hour following the discontinuation of the study drug. Repeated
      ABG analysis and spirometry will be carried out at that 1 hour to assess improvement over the
      pre-operative values. The administration of the spirometry exam will be by the same
      pulmonologist using the same spirometer device so as to minimize inter-observer variability.
      Arterial blood gas measurements will also be performed in the same analysis device.

      Protocol for Sedation & Analgesia: Dexmedetomidine (DEX) group: Initial loading dose of
      dexmedetomidine will be 1.0 μg/kg of dexmedetomidine administered over 10 minutes. Fifteen
      minutes after starting the study drug administration, patients will be assessed for their
      level of sedation using the Observer's Assessment of Alertness/Sedation Scale (OAA/S), and
      any patient having a score ≥3 will receive intravenous (IV) midazolam in 0.5 mg doses, which
      will be repeated until the OAA/S is ≤2. MIDAZOLAM/FENTANYL group: Patients will be assessed
      for their level of sedation using the Observer's Assessment of Alertness/Sedation Scale
      (OAA/S), and any patient having a score ≥3 will receive intravenous (IV) midazolam in 0.5 mg
      doses, which will be repeated until the OAA/S is ≤2 All subjects will receive local
      anesthesia prior to the commencement of the "open" trocar insertion technique performed by
      the thoracic surgeon at the point of introduction of the rigid trocar in the pleural cavity
      with a combination of lidocaine 1.5% and ropivacaine 0.75%. If a patient is not adequately
      sedated, rescue midazolam will be administered as single IV boluses of 0.5 mg, which will be
      repeated as needed to achieve an OAA/S score of ≤3. Intravenous fentanyl, 25 μg boluses which
      can be repeated as necessary, will be given if a patient expresses a pain score of ≥3 during
      the study drugs infusion and ≥4 in the PACU on a Verbal scale of 0-10 (0 = no pain, 10 =
      worst pain), or if the anesthetist determines the presence of pain when verbal communication
      is not possible. Blood gas analysis will be obtained at 30' and 60' minutes intraoperatively.
      The dexmedetomidine infusion will be discontinued after wound closure.

      At any time, if clinically indicated, the patient will be converted to an alternative
      sedative or anesthetic therapy and the study will be discontinued. OAA/S scores and all
      standard vital signs will be obtained every 5 min throughout the study drug infusion and
      before the administration of any rescue midazolam.

      The time to reach OAA/S =5 from the end of infusion will be recorded. Other data recorded at
      the end of surgery will include total fentanyl and midazolam used intraoperatively,
      crystalloid infusion in litres, total mcg of the study drug (provided a [dex] = 4 mcg/ml) and
      postoperative Visual Analogue Scale (VAS) pain score. If VAS>3 acetaminophen 1 g will be
      administered. The patient's monitoring will be continued in the post-anesthesia care unit
      (PACU) with vital signs been recorded every 5 minutes for the first 15 minutes, then every 15
      minutes for the next 45 minutes. Blood gas analysis will be obtained every 30' until
      discharge from the PACU. At 24 hours from the end of surgery, a spirometry will be performed.
      Patient satisfaction and surgeon satisfaction score will also be registered (4-point scale -
      0 min to 3 max). Patients will be discharged from the PACU when their OAA/S score =5.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Adult subjects who are scheduled for a pleuroscopy procedure.
      
Keywords: Monitored Anesthesia Care; Pleuroscopy; dexmedetomidine; fentanyl; midazolam; sedation