Chapter 125. Hematoma Blocks

Distal extremity fractures are commonly seen in the Emergency Department. These fractures often require closed reduction by manipulation, which can be a painful and frightening experience for the patient. Achieving adequate analgesia is important to facilitate reduction and to minimize patient discomfort. However, studies suggest that Physicians frequently provide inadequate analgesia to patients, and particularly children, with extremity fractures.1,2

The hematoma block is a technique to inject a local anesthetic solution into the hematoma between the fractured bone fragments. Fracture manipulation can then often be undertaken painlessly or with significantly reduced pain. Hematoma blocks of the distal forearm are considered safe in children and adults.3–8 Another advantage is the relative ease of the procedure. A hematoma block may be superior to intravenous sedation in alleviating discomfort during fracture reduction.9 The hematoma block, unlike procedural sedation, avoids the side effects of sedating drugs, does not require intravenous access and cardiac monitoring, and is not associated with a prolonged recovery phase. One Physician can safely perform a hematoma block, whereas the presence of two Physicians is generally recommended for procedural sedation. The disadvantages of the hematoma block include the discomfort and anxiety resulting from injecting into the fracture site, and the potential for a rare complication.

Extremity fractures, when displaced or angulated, generally result in the formation of a hematoma between the fracture fragments. The hematoma is easily accessible with a needle and the injection of local anesthetic solution can significantly alleviate pain. The majority of important neurovascular structures in the upper extremity are contained in the volar soft tissue, making the dorsal or lateral approach preferred. The majority of important neurovascular structures in the lower extremity are contained in the proximal anterior thigh or posteriorly in the leg, making the lateral approach preferred in the proximal thigh and the anterior or lateral approach from the mid-thigh distally.

Other techniques are available to provide analgesia and anesthesia. Some authors have concluded that a Bier block (intravenous regional anesthesia, Chapter 127) may lead to more effective anesthesia and require fewer re-manipulations for the reduction of forearm fractures when compared to the hematoma block.10–12 However, the Bier block is a technique that most Emergency Physicians are not familiar and have not developed proficiency, requires equipment not commonly available in the Emergency Department, and can be associated with adverse outcomes. Intraarticular injection of local anesthetic solution for the reduction of intraarticular fracture-dislocations, though not as well studied or widely utilized as a hematoma block, have also been advocated as safe and effective.13,14 The joints of the extremities are easily entered by performing an arthrocentesis (Chapter 77). Local anesthetic solution injected intraarticularly diffuses throughout the joint cavity and exits through the fracture site to alleviate pain.

A hematoma block is indicated in adult and pediatric patients with closed fractures of the extremity that require manipulation or closed reduction. Consider performing a hematoma block when medical resources are limited or scarce. It is an alternative when procedural sedation is impossible or impractical. A hematoma block may be performed purely for analgesia when fracture manipulation is unnecessary and/or other methods of analgesia are ineffective or contraindicated.

Hematoma blocks are contraindicated when there is a history of allergic reactions to local anesthetic agents. The procedure is also contraindicated in the setting of an open fracture, cellulitis overlying the fracture site, or the presence of a neurovascular deficit. A hematoma block should not be performed if a sterile field cannot be maintained or the safety of the medical staff cannot be assured due to an uncooperative patient. Relative contraindications include patients with bleeding disorders and those taking anticoagulants. The potential additional hemorrhage from the injection of local anesthetic solution into a closed space may result in a compartment syndrome.

• Sterile gloves and gown
• Face mask and cap
• Povidone iodine or chlorhexidine solution
• Sterile drapes
• Local anesthetic solution without epinephrine, usually 1% lidocaine
• Syringes, various sizes
• 22 or 23 gauge, 2-inch long needles
• Spinal needles for obese patients

Optional Equipment

• Ultrasound machine
• 7.5 to 10 MHz ultrasound probe
• Sterile ultrasound gel
• Sterile ultrasound probe cover

Explain the risks, benefits, complications, and alternatives to the patient and/or their representative. The technique for adult and pediatric patients is identical. An adult usually tolerates the hematoma block injection without any supplemental analgesia or sedation. Some adults and children may require supplemental nitrous oxide, intravenous sedation, or an intravenous anxiolytic agent to facilitate the hematoma block.

Prepare for the procedure. The hematoma block must be performed using strict aseptic technique. Cleanse the skin of any dirt and debris over the fracture site and surrounding skin. Apply povidone iodine or chlorhexidine solution onto the skin and allow it to dry. Apply sterile drapes to form a sterile field. The Emergency Physician should be wearing sterile gloves and a sterile gown during the procedure. The use of a face mask and cap is also recommended. Using aseptic technique, draw up sterile 1% lidocaine without epinephrine into a syringe armed with a 22 or 23 gauge, 2-inch long needle. A longer spinal needle may be required in the obese patient. Fill the syringe with 0.3 mL/kg to a maximum of 10 mL of lidocaine, the volume to be injected. Larger volumes maybe required in adults and larger fractures. Always be aware of the maximum safe dose of 4.5 mg/kg when using lidocaine without epinephrine.

Hematoma Block for Distal Radius Fractures

Follow strict aseptic technique throughout the procedure. Inform the patient of the early signs of local anesthetic toxicity. These include circumoral and tongue numbness, dizziness, lightheadedness, mental status decline, tinnitus, and visual disturbances. Instruct the patient to inform you immediately if they experience any of these symptoms.

Place a wheal of 1% lidocaine subcutaneously over the fracture site. Allow 1 to 2 minutes for the anesthetic to take effect. Slowly insert and advance the 23 gauge needle attached to the lidocaine-filled syringe through the skin wheal and aimed at the fracture site. Continue to slowly advance the needle toward and into the expected location of the gap between the fracture fragments (Figure 125-1). Aspirate with the syringe. A flash of blood indicates entry into the hematoma. If the needle strikes bone or if no flash of blood is returned, withdraw the needle and re-direct it in an attempt to enter the hematoma. Slowly inject the contents of the syringe into the hematoma. Withdraw the needle. Apply a bandage to the skin puncture site.

Some physicians reposition the needle to different areas within the hematoma and inject small amounts of the local anesthetic solution into each area. This technique distributes the local anesthetic solution to increase the efficacy of the hematoma block. Injection into multiple areas also minimizes the risk of intravascular injection of the entire dose of local anesthetic solution.

Hematoma Block for Intraarticular Fracture-Dislocations

The procedure is identical to that described above except for the anatomic landmarks and the volume of local anesthetic solution injected. Refer to Chapter 77 for the complete details of arthrocentesis.

Ultrasound-Guided Hematoma Block

Identify the fracture site and hematoma using ultrasound (US). Place the US probe on the patient's skin above the fracture site. Turn the US probe so its long axis is aligned with the long axis of the bone. Identify the fracture site and hematoma. Rotate the US probe 90° to visualize the short axis or cross-sectional view of the fracture site and hematoma.

Clean, prep, and sterilely drape the patient as described previously. Prepare the US probe. Apply US gel to the footprint of the US probe. Apply a sterile probe cover or a sterile glove over the US probe. Squeeze any air out of the space between the US probe and the cover. Apply sterile US gel on the probe cover.

Grasp the sterile US probe with the nondominant hand. Align the long axis of the US probe along the long axis of the bone and approximately 8 to 10 mm proximal to the fracture site. Aim the syringe containing the local anesthetic solution downward and in the direction of the fracture site. Slowly insert and advance the needle through the skin under US guidance. Advance the needle into the hematoma at the fracture site. Inject the local anesthetic solution. Remove the needle and apply a bandage to the skin puncture site.

Several adjuncts to the hematoma block may aid in increasing its efficacy. The addition of hyaluronidase to the local anesthetic solution has been advocated and become routine at some centers as a means of increasing the speed and efficiency of the hematoma block. The hyaluronidase breaks down the connective tissue and allows better penetration of the local anesthetic solution into the area. The evidence for the efficacy of hyaluronidase is currently lacking.15 Based on available data, it is not currently recommend to add hyaluronidase to the local anesthetic solution. The use of ultrasound can facilitate the injection into the correct site.16,17 Some authors recommend the use of other agents, such as anxiolytics, in combination with the hematoma block for fracture manipulation. Combining the hematoma block with nitrous oxide has shown positive results.18

Reassess and document a thorough neurologic and vascular examination distal to the fracture site immediately after the injection. Assess the patient's level of pain with gentle range of motion in 10 minutes. A second injection of local anesthetic solution may be performed if required for analgesia if the patient is not experiencing any side effects or toxicity and the total combined doses do not exceed the maximum allowable limit of 4.5 mg/kg.

The extremity can be manipulated to reduce the fracture once adequate analgesia has been obtained. Splint the extremity. Perform and document another neurologic and vascular examination of the extremity after any manipulation and splinting. Instruct the patient to immediately return to the Emergency Department for severe pain, significant swelling, numbness, paresthesias, or pallor of the extremity. Arrange appropriate follow-up with an Orthopedic Surgeon. Prescribe analgesics as appropriate.

The complications associated with a hematoma block are rare. These include a compartment syndrome, local anesthetic toxicity, and osteomyelitis.19–25 The early signs of local anesthetic toxicity include circumoral and tongue numbness, dizziness, lightheadedness, mental status decline, tinnitus, and visual disturbances. The cardiovascular toxic effects include asystole, atrioventricular blocks, bradycardia, cardiac depression, dysrhythmias, and hypotension. The neurologic toxic effects include agitation, coma, confusion, headaches, seizures, and possibly death. Seizures associated with local anesthetic toxicity are usually short lasting and respond to barbiturates, benzodiazepines, and propofol. Please refer to Chapters 123 and 127 for the complete details regarding local anesthetic complications and toxicity. Introducing bacteria into a previously closed fracture and injury to vascular structures are also potential complications. These can be minimized or eliminated by using strict aseptic technique and carefully identifying the anatomic landmarks.

A hematoma block is an effective technique to facilitate manipulation of extremity fractures and intraarticular fracture-dislocations in adults and children. It may also be performed purely for analgesia when no manipulation is required. Complications are rare if proper techniques are used. The procedure requires fewer Emergency Department resources than procedural sedation or a Bier block. Consider performing a hematoma block when procedural sedation is impractical or contraindicated. Patient preference should also be considered. Many patients would likely prefer a shorter Emergency Department stay with a hematoma block rather than a much longer one involving procedural sedation and the associated risks.