Intra-articular Versus Intravenous Dexmedetomidine in Arthroscopic Knee Surgeries Under Local Anesthesia

The present study will be carried to evaluate the efficacy of intra-articular 0.5 bupivacaine with intra-articular or intravenous alpha-2agonist; Dexmedetomidine; for intraoperative anesthesia and postoperative analgesia after arthroscopic knee surgery.

Arthroscopic knee surgery is one of the most common minimally invasive orthopedic procedures in recent practice which is frequently performed as a day surgery procedures. It can be done under general, regional or local anesthesia (LA) with or without sedation. It is associated with varying amount of postoperative pain. Postoperative pain negatively influences patient's early ambulation, rehabilitation and psychology which consecutively prolonged the hospital stay.

Intra-articular administration of local anesthetic for knee arthroscopy is a well-documented procedure that offers many advantages over other anesthesia types. Many anesthesiologists are still trying to improve the technique of local anesthetic administration through using many combinations with LA solutions in order to administer safe anesthesia to those patients and to obtain a pain-free knee with good operating conditions.

Dexmedetomidine is a highly selective α2 adrenergic agonist. It has analgesic, sedative, anxiolytic, hypnotic, sympatholytic, antihypertensive properties with anesthetic sparing effects. It becomes an attractive alternative to the current opioids because it does not have a respiratory depressant or addictive effect.

All patients were kept fasting after midnight and received midazolam 5 mg orally as premedication. All patients were premedicated with I.V. midazolam 0.03 mg/kg ten minutes before starting the operation. The anesthetic technique was standardized for all patients. All surgical procedures were performed by the same surgeon and consisted of arthroscopic removal of torn meniscus. Both intra-articular and intravenous solutions were prepared by an individual not involved in the study and the intra-articular drugs were injected by the surgeon (without knowing the contents). The anesthesiologist managing and monitoring the patient throughout the surgery provides IV drugs. No leg holder or tourniquet or surgical drain was used for any of the cases. After preparation and draping the patient's leg, patients were warned prior to each needle stick to decrease anxiety. All procedures were performed under complete aseptic conditions. Skin and subcutaneous tissues at each arthroscopic portal site were anesthetized with LA consisting of injection of a mixture of 2% lidocaine 5 mL with 1:200,000 epinephrine.

Care should be taken to avoid infiltration of the fat pad. It is a relatively aneural structure; as, too much local infiltration allows it to bulge out into the joint during the surgery. Flexion and extension of the knee joint several times help to spread of intra-articular solution and then waiting 20 minutes for anesthesia to take effect is helpful before the surgical incision.

The arthroscope was inserted into the knee, and inflow through the sheath was established. No pump was used for the saline inflow which was maintained through the arthroscope by the gravity. Gravity outflow drained through the superolateral portal. A separate egress cannula was used if indicated. The patient was encouraged to view the video monitor during the procedure. Constant verbal communication between the surgeon and the patient is important throughout the arthroscopic examination and surgery. This keeps the patient anxiety and muscle tension to the minimum which facilitates manipulation of the leg and thorough examination of the entire joint. Once finishing, instruments were removed and portals were closed with a 4-0 absorbable suture subcutaneously and steri-strips. A compression dressing was applied for three days to the knee.

Eligibility Criteria:
Inclusion Criteria:

* American Society of Anesthesiologists physical status I or II
* Patients scheduled for elective unilateral knee arthroscopy

Exclusion Criteria:

* Refusal of local anesthesia
* History of cardiovascular disease
* History of cerebrovascular disease
* History of respiratory diseases
* History of impaired renal functions
* History of impaired hepatic functions
* Pregnancy
* Allergy to the study drugs
* Uncontrolled diabetes
* Coagulopathies
* Hypertension treated with α methyldopa, clonidine or β adrenergic blockers
* Patients receiving chronic pain treatment
* Patients receiving psychoactive drugs
* Patients receiving anticoagulant drugs
* Prior ipsilateral knee surgery
* Infection at site of injection