Dexmedetomidine Premedication in Hypertensive Patients
Condition: Hypertension
MeSH terms: Hypertension
Study type: Interventional
Phase: Phase 3

Summary: 
      Hypertensive patients' often severe hypotensive response after induction of anesthesia and
      excessive increase in blood pressure to stresses such as laryngoscopy, intubation, surgical
      incision and extubation. There are many publications in the literature of preoperative
      evaluation of patients with hypertension and perioperative treatment of hypertension but is
      not sufficient about anesthetic management of these patients. Purpose of our study, was to
      investigate the haemodynamic effects of dexmedetomidine and midazolam used for premedication
      in hypertensive patients relative to each other and according to the normotensive patients.
    

Detailed description: 
      A total of 140 female patients, aged 40-60, normotensive or stage 1-2 hypertensive, scheduled
      for myomectomy or hysterectomy were randomly enrolled to 4 groups: Group ND
      (normotensive-dexmedetomidine); Group HD (hypertensive-dexmedetomidine); group NM
      (normotensive-midazolam); Group HM (hypertensive- midazolam). Twenty-one patients were
      excluded. The study drugs were administered 15 min before induction of anesthesia via
      intravenous infusion. Group ND (N= 29) received dexmedetomidine 0.5 µg.kg-1 in normotensive
      patient; Group HD (N= 30) received dexmedetomidine 0.5 µg.kg-1 in hypertensive patient; group
      NM (N= 30) received midazolam 0.025 mg. kg-1 in normotensive patient; Group HM (N= 30)
      received midazolam 0.025 mg. kg-1 in hypertensive patient. The study drugs was prepared by
      the anesthetist not included in the study in unlabeled syringes that determined by computer
      according to the group. The investigators and attending anesthesiologists were blinded to the
      randomization. Monitoring devices included noninvasive arterial blood pressure,
      electrocardiography, capnography, pulse oximetry and bispectral index.

      For induction of anesthesia with fentanyl 1 µg. kg-1 IV and propofol infusion was in the
      presence of BIS monitoring. Propofol infusion was stopped when BIS value was 60. Endotracheal
      intubation was performed after rocuronium 0.6 mg. kg-1 iv administered, Anesthesia was
      maintained with sevoflurane in air/oxygen 50:50 mixture, titrated to achieve a BIS value
      between 40 and 60. If the MBP value was increased > 25% of the baseline value on two
      consecutive readings within 2-3 min, antihypertensive therapy was administered
      (nitroglycerine 5 µg.min-1 iv infusion) after excluded possible cause ( inadequate
      anesthesia, hypoxia, hypercapnia etc). Bradycardia ( HR< 45 beat/min) persisting for > 2 min
      was treated with atropine 0.5 mg IV, boluses. At the end of the surgery sevoflurane turned
      off, and 100% oxygen was administered. Tramadol 1 mg.kg-1 IV was administered for
      postoperative pain control. Neuromuscular block was antagonized with neostigmine (0.04
      mg.kg-1 IV) and atropine (0.01 mg.kg-1 IV). Tracheal extubation was performed when obeying
      simple commands (open eye, squeeze hand etc) Systolic blood pressure (SBP), diastolic blood
      pressure ( DBP), mean blood pressure ( MBP) and heart rate ( HR) were recorded at several
      times as follows: baseline (T0 ), 5 minutes after administration of study drugs (T1), 10
      minutes after administration of study drugs (T2), immediately after induction (T3), 1 minute
      after intubation (T4), 5 minute after intubation (T5), at surgical incision (T6), 15 minutes
      after surgical incision (T7), 30 minutes after surgical incision (T8), 1 minute after
      extubation (T9), 5 minute after extubation (T10). Propofol amount for induction, time between
      induction and initial surgery, demand of antihypertensive therapy, rescue atropine were
      recorded. Side effects (bradycardia, dryness of the mouth, respiratory depression) were
      evaluated.

      The group sizes (N= 30) were calculated to detect a 25% changes in MBP value with a power of
      80% and a significance level of 0.05. Quantitative clinical and demographic characteristics
      were compared using One Way ANOVA. Chi-square tests (Likelihood ratio or Pearson) were used
      to examine the relationships between categorical demographic data and groups. Baseline
      measurements of hemodynamic parameters showed significant differences between groups for the
      initial values of the measurement period values have been adjusted by subtracting the
      beginning. The values obtained after the correction in respect of groups were compared using
      one-way analysis of variance. In addition, perioperative use of antihypertensive drugs that
      affect the measurements were evaluated by analysis of co-variance, but there is not
      significant effect was removed from the model. Additionally periodic variations were examined
      by One way Repeated Measures Analysis of Variance for groups separately, and a significance
      level of 0.05.
    

Intervention name(s): Midazolam; Dexmedetomidine
Intervention type(s): Drug; Drug
Intervention description(s): Midazolam was calculated by actual body weight of patients that had been diluted with saline to 40 ml. It was administered 15 min before induction of anesthesia via intravenous infusion. at a dose of 0.025 mg.kg-1; Dexmedetomidine was calculated by actual body weight of patients that had been diluted with saline to 40 ml. Dexmedetomidine was administered 15 min before induction of anesthesia via intravenous infusion. at a dose of 0.5 µg.kg-1
Other intervention name(s): Dormicum; Precedex
Intervention MeSH terms: Midazolam; Dexmedetomidine
Allocation: Randomized
Intervention model: Factorial Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Prevention
Keywords: hypertension; dexmedetomidine; midazolam; premedication