Using Lidocaine or Dexmedetomidine to Help Control Blood Pressure Spikes From a Tourniquet During Knee Surgery

Knee pain is very common and ambulatory knee arthroscopic surgery has increased significantly. Clinical studies comparing spinal anaesthesia to general anaesthesia (GA), have found that GA resulted in slightly shorter hospital stay, earlier mobilization, and fewer cases of urinary retention; that is why the investigators preferred in this study to choose the general anaesthesia over spinal anaesthesia in patients undergoing ambulatory knee arthroscopic surgeries. Tourniquet induced hypertension defined as an increase of at least 30% in the systolic blood pressure or diastolic blood pressure within one hour of the tourniquet inflation, which may affect the response to analgesia and the need for antihypertensive drug. The incidence of TIH in patients undergoing general anaesthesia using tourniquet is 67%. Previous studies were conducted to investigate the effect of different drugs such as Lidocaine, Ketamine or Dexmedetomidine in managing TIH. This study used Dexmedetomidine to decrease the TIH, and another one, used Lidocaine as bolus plus infusion to decrease the TIH, but to our knowledge no study was done to compare between both drugs in decreasing TIH. Dexmedetomidine is a selective, short acting agonist of the alpha 2 receptors, it has a sympatholytic effect, in addition to antihypertensive, anxiolytic, sedative and analgesic effects. Lidocaine is an anti-inflammatory drug with an analgesic and anti-hyperalgesia effect. It is also used in attenuating the stress response that can occur while using the laryngoscope. This study aimed to compare the effect of IV infusion of dexmedetomidine with the effect of IV Lidocaine in decreasing the TIH in patients undergoing ambulatory arthroscopic knee surgeries using the tourniquet under general anaesthesia. This randomized, comparative and double blinded study on 180 patients undergoing ambulatory knee arthroscopy under general anaesthesia using tourniquet. Patients were randomly allocated into two equal groups: Lidocaine group (group L): patients received lidocaine 2%, 1 mg/kg and dexmedetomidine group (group D): patients received a loading dose of (0.8 μg·kg-1 over 10 min) followed by continuous infusion of (0.4 μg·kg-1.h-1) diluted in 50 ml of normal saline.