using lidocaine or dexmedetomidine to help control blood pressure spikes from a tourniquet during knee surgery

Conditions: Tourniquet Hypertension

Summary: knee pain is very common, and more people are having minor knee surgeries done through a small camera (arthroscopy), often as outpatients. during these surgeries, a device called a tourniquet is used to reduce bleeding by stopping blood flow to the leg. however, this can sometimes cause a sharp rise in blood pressure-a condition known as tourniquet-induced hypertension (tih), which happens in about 67% of patients under general anesthesia. this study looked at two different drugs-dexmedetomidine and lidocaine- to see which one works better in preventing this blood pressure rise during surgery. dexmedetomidine is a medicine that calms the nervous system and helps lower blood pressure and pain, but it can sometimes cause side effects like a slow heart rate and low blood pressure. lidocaine, commonly used to numb pain, also helps with inflammation and controlling pain sensitivity. in this study, both drugs helped reduce tih, but dexmedetomidine was more effective. however, it came with more side effects compared to lidocaine.

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.

Eligibility criteria:
inclusion criteria: patients (males and females) of asa class i or ii, age from 18-60 years old, undergoing ambulatory knee arthroscopy under general anaesthesia using tourniquet. exclusion criteria: 1. patients with uncontrolled systemic diseases (e.g., diabetes mellitus, hypertension, and chronic obstructive lung disease), 2. patients with significant organ dysfunctions (e.g., cardiac, respiratory, renal, or liver disorders). 3. patients with morbid obesity (bmi \>35). 4. patients with a history of allergy to the drugs used in this study. 5. patients who have history of chronic use of opioids. 6. cases with tourniquet times of less than 60 minutes or longer than 150 minutes were excluded.

Keywords: lidocaine dexmedetomidine