Femoral Nerve block and Three-in-one block

Three-in-one nerve block may be used to block the femoral, obturator, and lateral femoral cutaneous nerves with a single injection. The femoral nerve runs down the thigh in a fascial sheath that is continuous with the nerve sheath that contains all three nerves more proximally. Just like FICB, the idea is to inject a large amount of local anaesthetic that will track proximally, medially, and laterally and thereby block all three nerves and provide more complete analgesia of the femoral neck and hip joint. 

The technique for performing both a femoral and three-in-one nerve block is identical except that the three-in-one block requires a larger volume of local anesthetic (25 to 30 mL versus 20 mL). Three-in-one nerve block provides better analgesia of the femoral neck and hip joint. 

Anatomy
The femoral nerve is formed from the posterior branches of L2-L4 and is the largest branch of the lumbar plexus. The nerve emerges from the psoas muscle and descends between the psoas and iliacus muscles. It passes under the inguinal ligament in the groove formed by these muscles lateral to the femoral artery and divides into anterior and posterior branches. 
The anterior branches innervate the anterior aspect of the thigh, and the posterior branches innervate the quadriceps muscle and continue below the knee as the saphenous nerve to provide sensory innervation from the medial side of the calf to the medial malleolus.

The lateral femoral cutaneous nerve arises from the second and third lumbar nerve roots. The nerve emerges from the lateral border of the psoas muscle and travels under the iliac fascia, across the iliac muscle, and under the inguinal ligament 1 to 2 cm medial to the anterior superior iliac spine. It branches into anterior and posterior branches 7 to 10 cm below the anterior superior iliac spine. The anterior branch innervates the skin over the anterolateral aspect of the thigh to the knee, whereas the posterior branch of the nerve innervates the lateral part of the thigh from the greater trochanter to the middle of the thigh.

The obturator nerve arises from the anterior divisions of L2-L4. It descends through the fibers of the psoas muscle and emerges from its medial border near the brim of the pelvis. It then passes behind the common iliac arteries and runs along the lateral wall of the lesser pelvis, above and in front of the obturator vessels to the upper part of the obturator foramen. Here, it enters the thigh through the obturator canal and divides into an anterior and a posterior branch. The obturator nerve is responsible for sensory innervation of the skin of the medial aspect of the thigh and motor innervation of the abductor muscles of the lower extremity.

Technique

• Arrange the equipment and take verbal/written consent
• Place the patient in a supine position
• Do a quick neuromuscular exam 
• Prepare the skin overlying the femoral triangle following usual aseptic precautions 
• Palpate the femoral artery 1 to 2 cm distal to the inguinal ligament and inject a subcutaneous wheal of local anaesthetic (1% Lignocaine) 1 to 2 cm lateral to this point. Keep the nondominant hand on the femoral artery throughout the remainder of the procedure. 

• Insert a 22-gauge needle just lateral to the artery at a 30-60 degree angle to the skin. Slowly advance the needle cephalad until one of the following occurs: 

1. a “pop” with sudden loss of resistance (signifying penetration into the femoral nerve sheath) is felt
2. a paresthesia is elicited, 
3. the needle pulsates laterally, which signifies a position adjacent to the femoral artery. Inject 25 to 30 mL of aesthetic (0.25% Bupivacaine). 

• The block usually takes 15 minutes to take effect. If proximity to the nerve is uncertain (e.g., a pop is not appreciated, a pares- thesia is not elicited, or the needle does not move with pulsa- tion of the femoral artery), inject the anesthetic in a fanlike distribution lateral to the femoral artery in an attempt to anesthetize the nerve.
• 
  
• It is also recommended to apply finger pressure 2 to 4 cm below the injection site to help spread the local anesthetic proximally to the obturator and lateral femoral cutaneous nerves. 

How is three-in-one block/femoral N block different from FICB?

The injection site for FICB is more lateral as compared to Femoral/Three-in-one block and thus FICB is less likely to injure the vessels. Additionally, FICB is a compartment block and thus requires more volume of local anaesthetic. 


Posted by:

              

     Lakshay Chanana

     

     Speciality Doctor

     Northwick Park Hospital

     Department of Emergency Medicine

     England

     @EMDidactic

Fascia Iliaca Compartment Block (FICB)

Nerve blocks are used in Emergency Departments to decrease the need for systemic analgesia and avoid opioid/NSAID side effects especially in elderly population. One of the commonly performed block is Fascia Iliaca Block for fractured femurs. The major advantage of a FICB is that the nerve and artery can be avoided as the site of injection is much lateral to Femoral artery in contrast to Femoral Block. It is important to note that FICB is a compartment block and thus needs at least 30ml of Local Anesthetic. 

Let's review the anatomy of femoral nerve and then go through through the landmark technique to perform FICB.

Anatomy 

Femoral Nerve

The femoral nerve is formed from the lumbar plexus ( L2 to L4). It supplies periosteum of the femur, motor innervation to the extensors of the knee, sensory innervation to the anterior thigh, anteromedial aspect of the knee, medial lower leg and the medial aspect of the ankle and foot. 

FN emerges below the inguinal ligament lateral the femoral vein and artery. It is covered by, and separated from the vascular bundle by the fascia iliaca. Overlying fascia iliaca, there is fascia lata which runs together with the fascia iliaca laterally. The fascia iliaca compartment within the pelvic brim also contains the lateral cutaneous nerve of the thigh laterally. This nerve supplies sensory supply to the lateral thigh.

Red dot on the image above represents the site of injection. Note, it is at least 2-3cm lateral from femoral artery unlike femoral block.  

FICB

This compartment allows deposition of local anaesthetic of sufficient volumes (at least 30mls) spread to at least two of the three major nerves that supply the medial, anterior and lateral thigh with one simple injection, namely the femoral and lateral femoral cutaneous nerves. Obturator nerve is often not blocked despite good technique. 

Indication: Peri-operative analgesia for patients with neck of femur or femoral shaft fractures. 

Contraindications

• Patient not co-operative or refusing
• Allergic reaction to Local 
• Infection over the site
• Previous femoral-bypass surgery
• Anticoagulation – INR >1.5 (Relative)

Equipment

1 One Compartment Tray 
1 FIB Needle
1 Injection needle 25G
1 Drawing Up needle 18G 
1 Syringe 5 ml
2 Syringes 20 ml
5 Gauze swabs 
Intralipid

Technique (Landmark)

• Place the patient supine and obtain Verbal/Written consent
• Do a neurovascular exam prior to the block
• Follow Aseptic precautions
• Draw a line between ASIS and Pubic Tubercle and divide it into 3 parts (see image below)
• Point of injection is 1-2cms inferior to this line at the junction of lateral and middle 1/3  (i.e 1cm inferior to the junction of medial 2/3 and lateral 1/3)
• Feel for femoral artery and ensure that you are at least 3-4 cm lateral to it. 
• Anesthetise skin with 2-3 ml 1% Lidocaine 
• Inject Bupivacaine - Advance the needle and feel for two distinct “pops” (fascia lata and then fascia iliaca). Advance the needle a further 1-2mm.
• Aspirate, and if negative inject slowly. There should be no resistance to injection. If there is, it means you are too deep. Withdraw the needle until injection is easy. There should be no pain or paraesthesia on injection. Inject slowly, aspirating with every 2-3 mls. 
• Withdraw the needle at the end of the procedure and apply a little pressure to the area for up to two minutes. The idea to to ensure maximum drug is delivered proximal to the site of injection and thus reaching all the three nerves. 

Draw a line between ASIS and Pubic tubercle and inject local 1cm inferior to the junction of medial 2/3 and lateral 1/3. Inject liberally at least 30mls of 0.25% Bupivacaine.

Take Home

• FICB is an effective way to provide pain relief and avoid side effects of systemic pain killers.
• It is a compartment and thus adequate amount of local needs to be injected. 
• It aims to block three nerves (Femoral, Obturator and Laternal Cutaneous). Despite a good technique, obturator is often not blocked. 

Posted by:

              

     Lakshay Chanana

     

     Speciality Doctor

     Northwick Park Hospital

     Department of Emergency Medicine

     England

     @EMDidactic

Trauma Calls and Pan CT - Are we doing it the right way?

Pan CT is almost becoming a norm for trauma, regardless of examination findings. Major Trauma Centers love it. Often patients fit into the "trauma activation" criteria but are stable enough to walk into the ED, look very well and have a completely unremarkable exam. 

Do we really need to activate "trauma call" and involve an anaesthetist, orthopod and surgeon for a patient who walked into the Emergency Department or should we just observe them for a few hours? 

Is it mandatory to scan them if they alert and oriented, look well, are hemodynamically stable but meet a significant injury criteria?

Well, every scenario is different and "pan scanning" and "trauma activation" depends entirely on your gestalt in addition to vital signs and exam findings. A 90 yo on NOACs can develop a Subdural and massive hemothorax due to fall from 3 feet height whereas a 30 year old may not sustain any injuries on falling from a height of 10 feet. My threshold to activate trauma for elderly is much low as minor falls can lead to significant injuries in older adults. But I always get perturbed when I see a patient being discharged (especially young patients) from resuscitation room after a pan-scan! 

There are plenty of other issues with pan scanning:

1. Clinically Insignificant Injuries

We might end up picking clinically insignificant injuries and then ponder what to do with them? Do they just need admission or follow up or a delayed intervention? More importantly, this adds to patient anxiety, additional use of resources. Arguments offered by the proponents of Pan CT are "we never know" and "what if we miss something" etc. Unfortunately, we live in a "no miss" culture and it can be a task to explain this to a distressed patient especially in case of a mishap. But very frequently, patients do understand the pros and cons of radiation and happy to accept minimal risk instead of radiation. Shared decision making (in low risk cases) and safety netting is the way to go rather than pan-scanning. And also remember, clinical examination still remains superior to pan-scans. With all this said, hard findings on exam should certainly mandate a relevant imaging. 

2. Radiation 
More scanning leads to more radiation exposure and higher chances of developing a malignancy in future. Click here to calculate risk of malignancy with various imaging studies. 

3. Skipping examination because we are doing a  CT

Sadly, CT Scanning is now become an excuse for not performing clinical examination. Working under immense pressures of timelines, scans are now being ordered without even evaluating a patient. More than often, physicians are correct in making these decisions but medicine is being practice the other way round where we see the blood results/imaging first and then greet the patient. 

As soon as you enter the room, the patient asks - Is my scan normal? A positive nod cuts the interview very short and saves our time but at the cost of irradiation. Clinical exam is then performed only as a formality. 

Scanning reassures the patients psychologically as well as the treating physician from a medico-legal standpoint. If we are likely to get sued for missing clinically insignificant injuries, then aren't we equally liable to land up in trouble for ordering an unwarranted pan-Scan. 

4. Holding life-saving treatment 

It is unacceptable to hold life saving intervention awaiting CT scan. For instance, decision to insert a chest drain is based on clinical exam and CXR/USG. Subcutaneous emphysema is enough to justify a chest tube insertion even if CXR does not show a clear Pneumothorax. Never withhold a life saving treatment awaiting a CT scan. CT scanning rarely changes the management of blunt chest trauma. In an ideal world, any unstable (hypotensive) trauma should go to OR based on the presumed site of blood loss. Outcomes can be dramatically improved if the Surgeons/Orthopods liaise well with each other. 

CT scans are not a part of primary survey in trauma. As a clinician, you must assess ABCDE at bedside and ensure hemodynamic stability prior to scanning. 

5. Cost and Utilisation of Resources
Pan-Scanning can cost anywhere between 20,000-30,000 INR at a private hospital in India. In government run healthcare systems, the issue is wastage of time and resources. 

The difference between physicians and other healthcare providers is that physicians use clinical judgement, weigh the pros and cons before taking a decision unlike most other allied healthcare workers who are trained to follow the protocols. We all know that everyone brought in with a "high risk" mechanism of injury may not need triple immobilisation, 2 wide bore IVs and Rectal Exams. Protocols are always made with a valid rationale behind them and should always have some degree of flexibility based on the clinical acumen of treating physician. 

Guidelines are made to guide us, not to be followed as hard and fast rules. 

Summary:

Patients who require pan-CT should be carefully selected based on gestalt, mechanism, vital signs and exam findings and not just based on the mechanism. Also, consider pan-scanning for those with difficult body habitus and altered mental status (of course with some clinical judgement). We need to be more responsible when we use the power of technology and make sure everything is done keeping in mind the best interests of our patients. There is something grossly wrong if we are frequently discharging patients from ED after pan scanning (This means we suspected multiple external or internal injuries on examination, but found none on Scanning). Consider observation and good safety netting in patients with low likelihood of injuries. Likewise, Trauma Call Activation needs to be individualised and we should not be blinded by the "high risk mechanism". 

Further Reading:

1. Surendran A, et al. Systematic review of the benefits and harms of whole-body computed tomography in the early management of multitrauma patients: are we getting the whole picture? J Trauma Acute Care Surg. 2014 Apr; 76(4):1122-30.
2. Holmes JF, Wisner DH, McGahan JP, et al. Clinical prediction rules for identifying adults at very low risk for intra-abdominal injuries after blunt trauma. Ann Emerg Med. 2009; 54:575-584. 
3. http://stemlynsblog.org/jc-always-need-whole-body-ct-trauma-st-emlyns/
4. http://thesgem.com/2017/06/sgem181-did-you-ever-have-to-make-up-your-mind-pan-scan-or-leave-other-scans-behind/
5. http://www.thebottomline.org.uk/summaries/em/react-2/
6. Kroczek EK, Wieners G, Steffen I, et al
   Non-traumatic incidental findings in patients undergoing whole-body computed tomography at initial emergency admission
   Emerg Med J  Published Online First: 27 January 2017. doi: 10.1136/emermed-2016-205722

7. Immediate total-body CT scanning versus conventional imaging and selective CT scanning in patients with severe trauma (REACT-2): a randomised controlled trial Sierink, Joanne C et al. The Lancet , Volume 388 , Issue 10045 , 673 - 683

   
   
   

   
   

   Posted by:

              

     Lakshay Chanana

     

     Speciality Doctor

     Northwick Park Hospital

     Department of Emergency Medicine

     England

     @EMDidactic

When to stay away from Amiodarone

This week, listen to Amal Mattu talking about Amiodarone. 

Does Amiodarone really fix everything?