Anesthesia Components of anesthesia amnesia anxiolysis analgesia akinesia attenuation of autonomic repsonses to noxious stimuli General Anesthesia Pharmacologically induced, reversible loss of conciousness, irrespective of airway management inhalational anesthesia by volatile liquids vaporized in a carrier gas including isoflurane sevoflurane desflurane nitrous oxide associated with increased gaseous abdominal distension leads to increased difficulty with fluoroscopic identification during pelvic and spinal procedures intravenous anesthesia non-opioids propofol etomidate benzodiazepines dexmedetomidine ketamine opioids fentanyl, alfentanil, sufentanil, remifentanil morphine hydromorphone neuromuscular blocking agents depolarizing agents bind to, depolarize, and transiently block ACh receptor short-acting: succinylcholine no intermediate or long-acting agents non-depolarizing agetns bind to and transiently block ACh receptor, but do not depolarize no short-acting agents intermediate-acting: rocuronium, vecuronium, atracurium, cisatracurium long-acting: pancuronium Local Anesthesia - Upper Extremity Interscalene regional block indications commonly used for shoulder/upper arm/elbow surgery technique performed by injecting local anesthetic to the nerves of the brachial plexus as it passes through the groove between the anterior and middle scalene muscles at the level of the cricoid cartilage complications sensory neuropathy is most common complication Supraclavicular block indications ideal for operations involving the arm and forearm, from the lower humerus down to the hand. technique targets brachial plexus superior to the clavicle complications hemidiaphragmatic paralysis supraclavicular nerve block has a higher incidence of hemidiaphragmatic paralysis than infraclavicular blocks nerve injury and intravascular injection pneumothorax, dyspnea damage to the subclavian artery Infraclavicular block indications ideal for operations involving the arm and forearm, from the lower humerus down to the hand. technique targets brachial plexus inferior to the clavicle Axillary block indications postoperative analgesia for surgery to the elbow, forearm, wrist and hand Bier block indications short (< 60 mins) operative procedures (i.e., carpal tunnel release) in the hand and forearm technique Esmarch exsanguination and tourniquet inflation inject lidocaine through a small, distal (hand) intravenous catheter on the surgical side deflate tourniquet after a minimum of 30 minutes to avoid venous release of local anesthetic and potential local anesthetic systemtic toxicity (LAST) Local Anesthesia - Spinal Spinal indications often used for knee and hip arthroplasty can be used for hip fracture surgery similar rates of postoperative delirium, 60-day mortality, and ambulatory capacity in comparison to general anesthesia technique a single injection with a small 24 or 27-gauge needle combination of morphine and bupivacain is often used complications spinal headache (decreased with small gauge needle), hematoma and opioid side effects (nausea, vomiting, purities, respiratory depression) Epidural indication often used for knee and hip arthroplasty technique similar to spinal anesthesia, except an indwelling catheter is placed combination of opioid and local anesthetic complications postoperative hypotension and motor impairment spinal headache, hematoma and opioid side effects (nausea, vomiting, pruritus, respiratory depression) Combined spinal epidural indications often used for knee and hip arthroplasty technique an epidural needle is placed into the epidural space and spinal anesthesia is administered through a spinal needle followed by placing an epidural catheter complications postoperative hypotension and motor impairment spinal headache, hematoma and opioid side effects (nausea, vomiting, purities, respiratory depression) Local Anesthesia - Lower Extremity Lumbar plexus/ psoas compartment nerve block indications surgeries involving the hip, anterior thigh and knee a sciatic block can be given concomitantly to provide pain relief to the entire lower extremity technique targets the lumbar plexus (L1 to L4 spinal nerves) which form the obturator nerve, lateral femoral cutaneous nerve, and femoral nerve the injection is usually placed 3-5 cm lateral to the spinous process of L4 and is often guided by ultrasound and nerve stimulators complications nerve damage and intravascular injection epidural diffusion, retroperitoneal hematomas, intrathecal injections and an increased risk of falls Fascia iliaca compartment block indications surgeries involving the hip, anterior thigh, and knee has been shown to significantly decrease the risk of postoperative delirium following geriatric hip fracture surgery technique targets the femoral, obturator, and lateral femoral cutaneous nerves 1 cm caudal to a point dividing the lateral 1/3 and medial 2/3 of a line extending from the pubic tubercle to the ASIS often guided by ultrasound complications local hematoma, nerve damage, or intravascular injection Femoral nerve block indications surgeries around the knee concomitant sciatic nerve block can be done to increase analgesia around the knee technique targets the femoral nerve (L2-L4) the injection occurs just lateral to the femoral artery and on a line connecting the anterior superior iliac spine to the pubic symphysis complications nerve damage and intravascular injection increased risk of falls, prolonged quadriceps weakness and infections adductor canal block can be performed more distally to preserve mobility after TKA Sciatic nerve block indications surgeries involving the leg, ankle and foot can be combined with the femoral or lumbar plexus block to provide analgesia to the entire lower extremity technique targets the sciatic nerve providing analgesia to the common peroneal and tibial nerves multiple techniques have been described lines are drawn between the greater trochanter and the posterior superior iliac spine (PSIS), and the greater trochanter and the sacral hiatus halfway between the greater trochanter and the PSIS a perpendicular line is drawn, and the injection is placed where the perpendicular line crosses the line between the greater trochanter and the sacral hiatus complications nerve damage and intravascular injection vascular injury, heel ulcers and a delay in diagnosis of nerve injuries after surgery Obturator nerve block indications adductor muscle spasm, severe hip pain from osteoarthritis adjuvant pain management for knee surgeries technique targets the anterior and posterior branch of the obturator nerve blocking the anterior branch leads to decreased sensation at the hip joint and inner thigh, where blocking the posterior branch decreases sensation around the knee injection site is usually 2 cm inferior and 2 cm lateral to the pubic tubercle complications nerve injury and intravascular injection damage to structures in the pelvic cavity Popliteal nerve block indications used for surgery around the foot and ankle often used in conjunction with the saphenous nerve block technique targets the sciatic nerve prior to its bifurcation injection site is often 10 cm proximal to the popliteal crease complications nerve injury and intravascular injection hematoma, persistent foot drop and pressure sores Saphenous nerve block indications procedures around the medial aspect of the knee, leg and ankle technique targets the saphenous nerve multiple different techniques, but it is often blocked behind the sartorius muscle complications nerve injury and intravascular injection hematoma and infection Periarticular injection Important for analgesia in Total Knee and Total Hip Arthroplasty For Total Knee Arthroplasty, has been associated with improved pain control compared to the iPACK (interspace between the popliteal artery and the capsule of the posterior knee) Blood Management Ways to reduce postop anemia and need for allogeneic transfusion surgical hemostasis meticulous dissection hypotensive epidural anesthesia (HEA) epidural dermatomal block from T2 distal blocks cardio-accelerator fibers of sympathetic chain causes bradycardia which is treated with low-dose epinephrine lowers MAP to 50mmHg keeps normal heart rate, CVP, stroke volume, cardiac output can be used in high risk patients with hypertension poor cardiac function chronic kidney disease Complications Malignant hyperthemia rare (1:15,000 to 1:50,000) life-threatening condition autosomal dominant transmission abnormalities in the ryanodine receptor (RYR1) gene triggers volatile inhalational anesthetic agents succinylcholine symptoms hypermetabolic state increased skeletal muscle contraction and metabolism rigidity masseter spasm rapid oxygen depletion increased carbon dioxide concentration (EtCO2) and body temperature outcome if untreated, leads to circulatory collapse and death treatment provide antidote active cooling antidote dantrolene (calcium blocker) Local anesthetic systemic toxicity (LAST) intravascular bupivicaine effect CNS seizures, coma, respiratory arrest CVS asystole, ventricular fibrillation, cardiac arrest antidote intravenous 20% lipid emulsion Bone cement implanation syndrome associated with use of bone cement during joint arthroplasty procedures symptoms hypotension hypoxemia treatment intravenous fluids vasopressors 100% inspired oxygen