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Lower Extremity Regional Anesthesia - Overview

Authors

James Mattson, MD

Summary

  • Ultrasound-guided nerve blocks have been shown to be practical in an emergency room environment and effective in pain control for acute injuries or regional anesthesia for emergency room procedures. [1]Beaudoin FL, Haran JP, Liebmann O. A comparison of ultrasound-guided three-in-one femoral nerve block versus parenteral opioids alone for analgesia in emergency department patients with hip … Continue reading [2] Bhoi S, Chandra A, Galwankar S. Ultrasound-guided nerve blocks in the emergency department. J Emergencies, Trauma Shock. 2010;3(1):82-88. doi:10.4103/0974-2700.58655  

Lower Extremity Neuroanatomy

  • Lumbosacral Plexus
    • The lumbosacral plexus originates from the spinal nerves L1 to S4. It divides into four nerves that innervate the lower extremity: lateral femoral cutaneous, femoral, obturator, and sciatic. The femoral nerve provides motor and sensory function to the anterior thigh, then continues as the saphenous nerve to provide sensation to the medial leg, foot, and great toe. The obturator provides sensation to the medial thigh and motor function to the adductors. 
Lumbosacral Plexus Anatomy[3], Image courtesy of wikipedia.org, “Lumbar Plexus”
    • The lateral femoral cutaneous supplies sensation to the lateral thigh. The sciatic nerve supplies sensation to the posterior thigh via the posterior cutaneous nerve of the thigh, then divides into the tibial and common peroneal nerves which supply motor function to the lower leg and sensation to the anterior, lateral, and posterior regions of the leg. [4] Rodziewicz TL, Patel S, Garmon EH. Lower Extremity Blocks. StatPearls. 2020.
  • Sciatic nerve
    • The sciatic nerve is the largest peripheral nerve in the body, arising from nerve roots L4 to S3. In the gluteal region, this nerve lies lateral to the proximal tendons of semitendinosus-biceps and semimembranosus. Though it travels through the posterior thigh before bifurcation in the popliteal fossa, the proximal sciatic nerve is composed of separate nerve fibers for the common fibular and tibial nerve, which do not mix. 
Sciatic Nerve Anatomy[5], Image courtesy of https://teachmeanatomy.info/, “The Sciatic Nerve”
    • This means even the proximal sciatic nerve contains two separate nerves in the nerve bundle. The sciatic nerve divides into the common peroneal nerve and tibial nerve, both of which provide motor and sensory innervation to the lower leg (see sections below). [6] Silvestri E, Martino F, Puntillo F. Ultrasound-guided peripheral nerve blocks. In: Silvestri E, Martino F, Puntillo F, eds. Ultrasound-Guided Peripheral Nerve Blocks. ; 2018. doi:10.2199/jjsca.28.103 [7] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd editio. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [8]Goldsmith AJ, Liteplo A, Hayes BD, Duggan N, Huang C, Shokoohi H. Ultrasound-guided transgluteal sciatic nerve analgesia for refractory back pain in the ED: A case series. Am J Emerg Med. … Continue reading
  • Saphenous Nerve
    • The saphenous nerve is the terminal branch of the femoral nerve and supplies sensory innervation to the medial leg, medial malleolus, and medial aspect of foot. It travels through the adductor canal and pierces the fascia lata in between the tendons of the sartorius and gracilis of the pes anserinus. The nerve then travels down the medial aspect of the leg along with the saphenous vein, crossing into the foot anterior to the medial malleolus and supplying sensory branches to the ankle joint. [9] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [10] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7
Saphenous Nerve Anatomy and Distribution[11]Image courtesy of https://emedicine.medscape.com/,”Saphenous Nerve Block”
  • Tibial Nerve
    • The tibial nerve is the largest branch of the sciatic nerve. It continues from the popliteal fossa in a straight course in the deep posterior compartment of the leg and travels posterior to the medial calcaneus with the tendons of posterior tibialis, flexor digitorum longus and flexor hallucis longus. In the foot, it branches into medial and lateral plantar nerves that supply sensory innervation to the heel region, sole of the foot, and all toes including nailbed. [12] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [13] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7
Tibial Nerve Anatomy[14]Image courtesy of https://teachmeanatomy.info/,”Tibial Nerve”
  • Deep Peroneal Nerve
    • The deep peroneal nerve is a branch of the common peroneal nerve that supplies sensory innervation to the web space between the first and second toes. After the common peroneal nerve separates from the tibial nerve it traverses the popliteal fossa in a medial to lateral trajectory, then crosses laterally around the head of the fibula. The deep peroneal then arises in the lateral compartment before entering the anterior compartment to travel down the leg with the anterior tibial artery. The deep peroneal nerve lies lateral adjacent to the anterior tibial artery in between the tibial and extensor hallucis longus muscle. [15] Silvestri E, Martino F, Puntillo F. Ultrasound-guided peripheral nerve blocks. In: Silvestri E, Martino F, Puntillo F, eds. Ultrasound-Guided Peripheral Nerve Blocks. ; 2018. doi:10.2199/jjsca.28.103 [16] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3
Deep Peroneal (Fibular) Nerve Anatomy (green)[17]Image courtesy of https://teachmeanatomy.info/,”The Deep Fibular Nerve”
  • Superficial Peroneal Nerve
    • The superficial peroneal nerve is a branch of the common peroneal nerve that arises at the head of the fibula. It provides sensory innervation to the anterior ankle and dorsum of the foot. It emerges from the fibular head in the lateral (70%) or anterior compartment and travels along the muscular compartment before emerging through the fascia lata into the subcutaneous tissue of the lateral leg. [18] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3
Superficial Peroneal (Fibular) Nerve Anatomy (blue)[19]Image courtesy of https://teachmeanatomy.info/,”The Deep Fibular Nerve”
  • Sural Nerve
    • The sural nerve derives from the medial sural cutaneous nerve, a branch of the tibial nerve, and the lateral sural cutaneous nerve, a branch of the superficial peroneal nerve. It supplies sensory innervation to the lateral foot and fifth toe. This nerve emerges from between the medial and lateral heads of the gastrocnemius and joins the small saphenous vein in a fascial compartment on the lateral leg. The two then travel posterior to the lateral malleolus to the lateral foot. [20] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [21]Cisewski DH, Alerhand S. ‘SCALD-ED’ Block: Superficial Cutaneous Anesthesia in a Lateral Leg Distribution within the Emergency Department – A Case Series. J Emerg Med. 2019;56(3):282-287. … Continue reading
Sural Nerve[22]Image courtesy of https://pivotalmotion.physio/,”WHAT IS THE SURAL NERVE?”
  • Femoral Nerve
    • The femoral nerve is made up from dorsal divisions of anterior rami from L2, L3, and L4. This nerve provides motor innervation to pectineus, sartorius, and quadriceps. Distal sensory nerve branches include the anterior cutaneous nerve of the thigh, the infrapatellar nerve and the saphenous nerve. These provide sensation to the anterior thigh, medial leg, and arch of foot. The femoral nerve travels in between the psoas and iliacus muscles proximal to the inguinal ligament, then anterior to the iliopsoas muscle before passing underneath the inguinal ligament. It lies lateral to the femoral artery and is usually oval or triangular in shape. [23] Silvestri E, Martino F, Puntillo F. Ultrasound-guided peripheral nerve blocks. In: Silvestri E, Martino F, Puntillo F, eds. Ultrasound-Guided Peripheral Nerve Blocks. ; 2018. doi:10.2199/jjsca.28.103 [24] Ghisi D, Delaunay L, Fanelli A. Use of ultrasound for lower extremity. Curr Opin Anaesthesiol. 2014;27(5):528-537. doi:10.1097/ACO.0000000000000119 [25] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3
Femoral Nerve Anatomy[26]Image courtesy of https://teachmeanatomy.info/,”The Femoral Nerve”
  • Lateral Femoral Cutaneous Nerve
    • The lateral femoral cutaneous nerve (LFCN) originates from the lumbosacral plexus from L2 and L3 nerve roots. It traverses the iliacus muscle in the pelvis and enters the thigh medial to the anterior superior iliac spine (ASIS). The LFCN crosses over or pierces through the sartorius muscle from medial to lateral. The LFCN may split into several branches before supplying sensory innervation to the lateral thigh. The sensory territory of the LFCN can often extend distal to the knee. [27] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [28] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7
Lateral Femoral Cutaneous Nerve Anatomy[29]Image courtesy of https://www.painspa.co.uk/,”Lateral Femoral Cutaneous Nerve Block”
  • Obturator
    • The obturator nerve originates from anterior rami of L2, L3, and L4 and travels through the pelvis crossing over the psoas major muscle at the level of the sacroiliac joint, and exits the pelvis through the obturator. It has anterior and posterior divisions that lie superficial and deep to the adductor brevis. The obturator nerve provides motor innervation to the adductor muscles. It has variable cutaneous sensory innervation that includes the medial thigh. [30] Silvestri E, Martino F, Puntillo F. Ultrasound-guided peripheral nerve blocks. In: Silvestri E, Martino F, Puntillo F, eds. Ultrasound-Guided Peripheral Nerve Blocks. ; 2018. doi:10.2199/jjsca.28.103 [31] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3
Obturator Nerve Anatomy[32]Image courtesy of https://teachmeanatomy.info/,”The Obturator Nerve”

Nerve Ultrasound Principles

  • Nerves are made up of multiple fascicles which are each surrounded by perineurium. Bundles of these fascicles make up a single nerve, which is surrounded by epineurium. When visualized in cross-section, this creates a typical cable or “honeycomb” appearance on ultrasound, made up of hyperechoic epineurium surrounding a bundle of hyperechoic perineuria wrapping hypoechoic round areas. In longitudinal plane, the nerve appears as a long slim structure with multiple hyperechoic parallel lines representing perineurium. [33] Silvestri E, Martino F, Puntillo F. Ultrasound-guided peripheral nerve blocks. In: Silvestri E, Martino F, Puntillo F, eds. Ultrasound-Guided Peripheral Nerve Blocks. ; 2018. doi:10.2199/jjsca.28.103
  • Nerves are usually in between fascial planes, including often surrounded by fascial paraneurium. More effective anesthesia is achieved when local anesthetic is injected in between epineurium and paraneurium. This can be achieved by visualizing the needle approaching the nerve in a tangential approach to avoid direct intraneural penetration, then using a loss of resistance sensation to indicate entrance into the paraneurium. The optimal spread of local analgesia would then form a circumferential spread around the nerve between the paraneurium and epineurium. [34] Ghisi D, Delaunay L, Fanelli A. Use of ultrasound for lower extremity. Curr Opin Anaesthesiol. 2014;27(5):528-537. doi:10.1097/ACO.0000000000000119

Overview of Blocks By Site

Hip/Femur, Groin, Buttocks

Fascia Iliaca Block
  • The fascia iliaca is a layer of fascia that connects the internal oblique and sartorius muscles and overlies the muscle body of the iliacus. The fascia iliaca block is performed by injecting anesthetic into tissue plane between iliacus muscle and fascia iliaca. The injection is in between LFCN and femoral nerve, and with sufficient volume can reach other nerves of the lumbosacral plexus including genitofemoral, obturator, and ilioinguinal nerves. [35] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [36] Mittal R, Vermani E. Femoral nerve blocks in fractures of femur: Variation in the current UK practice and a review of the literature. Emerg Med J. 2014;31(2):143-147. doi:10.1136/emermed-2012-201546 [37] Salinas F V. Ultrasound and review of evidence for lower extremity peripheral nerve blocks. Reg Anesth Pain Med. 2010;35(2 Suppl). doi:10.1097/aap.0b013e3181d245df
  • A femoral nerve block has been shown to achieve pain relief for hip or femur fractures. [38] Mittal R, Vermani E. Femoral nerve blocks in fractures of femur: Variation in the current UK practice and a review of the literature. Emerg Med J. 2014;31(2):143-147. doi:10.1136/emermed-2012-201546
  • Using ultrasound for femoral nerve blocks has been shown to improve onset of analgesia, lower required anesthetic dose, and decrease risk of vascular puncture or intraneural injection. [39] Mittal R, Vermani E. Femoral nerve blocks in fractures of femur: Variation in the current UK practice and a review of the literature. Emerg Med J. 2014;31(2):143-147. doi:10.1136/emermed-2012-201546
  • A fascia iliaca block can achieve pain relief in hip or femur fractures and increased tolerance of a thigh tourniquet. [40] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3
  • Ultrasound guidance has shown to achieve higher rates of success and more rapid anesthesia and to use less volume anesthetic as compared non-ultrasound methods such as loss of resistance and nerve stimulation. [41] Salinas F V. Ultrasound and review of evidence for lower extremity peripheral nerve blocks. Reg Anesth Pain Med. 2010;35(2 Suppl). doi:10.1097/aap.0b013e3181d245df
3-in-1 Block
  • The three-in-one block of the femoral nerve has also been described as a method of anesthetizing the femoral nerve, LFCN, and obturator nerve. This technique was described as positioning the ultrasound probe 1cm distal to inguinal ligament and 1cm lateral to femoral artery to visualize femoral nerve. The needle is then inserted in in-plane view in lateral to medial trajectory at 45 degree angle towards femoral nerve into the fascia iliaca tissue plane. A volume of 20-25mL of local anesthetic is injected into perineural sheath while applying pressure distally on femoral nerve. This allows for anesthetic spread proximally within neural sheath, which is shared by LFCN and obturator nerves. [42]Beaudoin FL, Haran JP, Liebmann O. A comparison of ultrasound-guided three-in-one femoral nerve block versus parenteral opioids alone for analgesia in emergency department patients with hip … Continue reading Note that when performed successfully, the needle will not engage the femoral nerve directly but anesthetize via tracking along the fascia iliac tissue plane.
  • A placebo-controlled randomized control trial showed the three-in-one block to be more effective than parenteral opioids in relief of pain from acute hip fractures in the emergency room with no added rate of adverse effects or complications. [43]Beaudoin FL, Haran JP, Liebmann O. A comparison of ultrasound-guided three-in-one femoral nerve block versus parenteral opioids alone for analgesia in emergency department patients with hip … Continue reading
Peng Block
  • The pericapsular nerve group (PENG) block is a newly described block which offers anesthesia to the anterior capsule of the hip joint and is useful for intracapsular fractures, such as femoral neck fractures
  • It blocks the suprainguinal articular branches of the femoral nerve as well as the obturator nerve (ref???). 
  • This block, however, does not guarantee relief of extracapsular fractures, such as intertrochanteric fractures, and runs the risk of introducing infection into the joint so must be done under sterile conditions. 
Dorsal Penile Block
  • The innervation to the penis arises from the sacral nerve roots via the pudendal nerve, which divides in the pudendal canal terminating in branches to the dorsal penis. 
  • The dorsal penile nerves lie just deep to the deep fascia (Buck’s fascia) and adjacent to the dorsal vessels. 
  • Blocking this nerve can provide anesthesia prior to reduction of a paraphimosis.
Lateral Femoral Cutaneous Block
  • A LFCN nerve block can achieve sensory block to the lateral thigh for procedures or pain control, and is used for treatment for meralgia paresthetica [44] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7  
  • Technique for a LFCN nerve block begins with locating the nerve as it traverses medial to lateral over the sartorius. Scan down from ASIS along sartorius in coronal plane to visualize LFCN as it crosses superficial to or through the muscle. Another approach is identifying the LFCN as it travels through space between tensor fascia lata and sartorius. Injection can be done using in-plane or out-of-plane technique. A gel standoff may be useful particularly in thin patients. [45] Ghisi D, Delaunay L, Fanelli A. Use of ultrasound for lower extremity. Curr Opin Anaesthesiol. 2014;27(5):528-537. doi:10.1097/ACO.0000000000000119 [46] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3

 

Knee & Leg

Popliteal-Sciatic Block
  • The sciatic nerve can be visualized and anesthetized proximally lateral to origins of hamstrings, or distally in popliteal fossa. [47] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [48]A lateral decubitus position can allow for visualization of the sciatic nerve for a transgluteal approach. In this position, the sciatic nerve can be seen in between the greater tuberosity and … Continue reading
  • A sciatic nerve block, when combined with femoral nerve block, can allow for complete anesthesia to the lower extremity. [49] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3
  • A sciatic block has been suggested as a potential emergency department treatment for acute on chronic radiculopathy from lower lumbar disc extrusion. [50]Goldsmith AJ, Liteplo A, Hayes BD, Duggan N, Huang C, Shokoohi H. Ultrasound-guided transgluteal sciatic nerve analgesia for refractory back pain in the ED: A case series. Am J Emerg Med. … Continue reading
  • A transgluteal sciatic nerve block can anesthetize skin of buttock to allow for incision and drainage of gluteal abscesses. [51]Selame LA, McFadden K, Duggan NM, Goldsmith AJ, Shokoohi H. Ultrasound-Guided Transgluteal Sciatic Nerve Block for Gluteal Procedural Analgesia. J Emerg Med. 2020;Published:1-5. … Continue reading
Saphenous Block
  • A saphenous nerve block can anesthetize the arch of the foot, medial aspect of leg, and ankle joint. [52] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [53] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7
  • The saphenous nerve can be blocked proximally at the adductor canal. This anesthetizes distally on the medial aspect of the leg. [54] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3
Genicular Block

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Infiltration of local anesthetic between the Popliteal Artery and Capsule of the Knee (IPACK) Block

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Foot & Ankle

Popliteal-Sciatic Block

See above

Saphenous Block

See above

Posterior Tibial Block
  • A tibial nerve block provides sensory block to the sole of the foot and all five toes. This a useful technique for laceration repair or exploration and removal of foreign bodies from the sole of the foot, or for injections of the plantar fascia. [55] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7 [56]Moake MM, Presley BC, Barnes RM, Deanehan JK. Ultrasound-Guided Posterior Tibial Nerve Block for Plantar Foot Foreign Body Removal. Pediatr Emerg Care. 2020;36(5):262-265. … Continue reading
Deep Peroneal Nerve
  • A block of the deep peroneal nerve can provide sensory blockade to the web space in between the first and second toes. [57] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7
Superficial Peroneal Nerve Block
  • A superficial peroneal nerve block can anesthetize the dorsum of the foot for procedures in that site. [58] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [59] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7
Sural Nerve Block
  • A sural nerve block can anesthetize the lateral foot. The sural nerve block often needs to be combined with superficial peroneal nerve and/or tibial nerve block to anesthetize the fifth toe. [60] Gray AT. Lower Extremity Blocks. In: Gray AT, ed. Atlas of Ultrasound-Guided Regional Anesthesia. 3rd edition. ; 2014:144-232. doi:10.1016/B978-0-323-50951-0.00001-3 [61] Yurgil JL, Hulsopple CD, Leggit JC. Nerve Blocks: Part II. Lower Extremity. Am Fam Physician. 2020;101(11):669-679. doi:10.1016/S1875-5364(20)30046-7
  • A block of specifically the lateral sural cutaneous nerve as it branches from the superficial peroneal has been shown to provide effective anesthesia to the lateral aspect of the leg. [62]Cisewski DH, Alerhand S. ‘SCALD-ED’ Block: Superficial Cutaneous Anesthesia in a Lateral Leg Distribution within the Emergency Department – A Case Series. J Emerg Med. 2019;56(3):282-287. … Continue reading

Pearls and Pitfalls

References[+]