Preop Dexmedetomidine Attenuates Haemodynamic Responses to Hydrodissection
Condition: Robotic Thyroidectomy
Study type: Interventional
Phase: Phase 4

Summary: 
      Percutaneous tunnelling (hydrodissection) in the neck and anterior chest in patients
      undergoing robotic thyroidectomy leads to significant haemodynamic responses such as
      increases in blood pressure and heart rate. The investigators evaluated whether a single
      preoperative dexmedetomidine injection attenuated the haemodynamic responses to
      hydrodissection by reducing the half-maximal effective concentration (EC50) of remifentanil
      needed to maintain haemodynamic stability during hydrodissection.
    

Detailed description: 
      Dexmedetomidine (DXM) is a recently released and approved alpha 2 agonist with a relatively
      high ratio of α2/α1-activity and an almost fourfold shorter half-life than clonidine.It's
      sympatholytic, sedative, and analgesic properties makes DXM a useful anaesthetic adjuvant for
      general anaesthesia. While there are some reports of the beneficial effects of DXM on
      anaesthetic requirements and haemodynamic responses to endotracheal intubation, the effect of
      a single preoperative injection of DXM in terms of attenuating haemodymanic responses to
      surgical stimulation in robot-assisted thyroidectomy is unknown.

      When a robotic thyroidectomy using the bilateral axillary breast approach (BABA) technique is
      performed, subcutaneous tunnelling in the neck and anterior chest, which is defined as
      hydrodissection, is mandatory. Unfortunately, the procedure leads to significant haemodynamic
      responses, such as increases in blood pressure and heart rate.

      We hypothesised that preoperative DXM administration would attenuate the haemodynamic
      responses to hydrodissection. This study was designed to evaluate the effects of a single
      preoperative administration of DXM on haemodynamic responses to hydrodissection in robotic
      thyroidectomy by comparing the half-maximal effective concentration (EC50) of remifentanil
      needed to maintain haemodynamic stability during hydrodissection between DXM and control
      groups. We also investigated the effects of preoperative DXM administration on total doses of
      remifentanil and propofol administered intraoperatively.
    

Intervention name(s): DXM + Propofol; Saline + Propofol
Intervention type(s): Drug; Drug
Intervention description(s): After induction as mentioned at 'arm description', the effect-site propofol concentration was fixed at 5.0 μg mL-1 at the time of diluted epinephrine injection and was unchanged during the entire hydrodissection period in all patients.
The first patients received effect-site concentrations of remifentanil of 4 ng mL -1, respectively. The EC50 of remifentanil for stable hydrodissection was determined by a modification of Dixon's up-and-down method.If the response was "success (SBP during the entire hydrodissection period being ±20% from baseline)," the next target concentration of remifentanil was decreased by a step of 0.5 ng mL -1. If the response was "fail(SBP > ±20% from baseline)," the target concentration was increased by 0.5 ng mL-1.; All procedure would be same in DXM+Propofol group except saline loading rather than DXM loading before induction.
Intervention MeSH terms: Propofol
Allocation: Randomized
Intervention model: Single Group Assignment
Masking: Triple (Care Provider, Investigator, Outcomes Assessor)
Primary purpose: Supportive Care