Preop Dexmedetomidine Attenuates Haemodynamic Responses to Hydrodissection

A Single Preoperative Injection of Dexmedetomidine Attenuates Haemodynamic Responses to Hydrodissection in Patients Undergoing Robotic Thyroidectomy: a Prospective Randomised Double-blinded Study

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.

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.

Inclusion Criteria:

• ASA physical status I-II patientsscheduled for general anaesthesia for robotic thyroidectomy

Exclusion Criteria:

• Patients with an allergy to α2-adrenergic agonists or propofol
• Patients with current antihypertensive medication
• Patients with heart block > 1 degree
• Patients with severe cardiorespiratory dysfunction
• Patients with history of alcohol or drug abuse
• Patients who had received an opioid analgesic medication within the previous 24-h period before the operation