Femoral nerve block to facilitate painless device closure of atrial septal defect

Pravin Kumar¹, Mani Ram. K^2*, S. P. Vinothkumar ³, Murshid Ahmed⁴, Deepak⁴, Preethi⁴

¹Consultant Cardiac Anaesthesiologist, Kauvery Hospital, Heart City, Trichy, Tamil Nadu

²Consultant Paediatric Cardiologist, Kauvery Hospital, Heart City, Trichy, Tamil Nadu

³Consultant Paediatric Cardiologist, Kauvery Hospital, Maa Kauvery, Trichy, Tamil Nadu

⁴PG – Residents, Kauvery Hospital, Maa Kauvery, Trichy, Tamil Nadu

Introduction

The closure of atrial septal defect (ASD) is now routinely performed by using a percutaneous approach for which local anesthesia infiltration with 1% lignocaine is routinely used. A large vascular sheath (usually more than 10 Fr diameter) is introduced through the femoral vein. The introduction of the sheath through the groin into the femoral vein is painful and patients often experience vasovagal hypotension during the procedure because of inadequate local anaesthesia. This can be negated by a femoral nerve block (FNB) prior to the procedure. We report the case of a 45-year-old female patient with a large ostium secundum ASD in whom a FNB alleviated pain associated with vascular sheath introduction

Case Presentation

A 45-year-old female patient with functional class II symptoms. She was diagnosed with asymptomatic ASD for many years. Her heart rate was 82 beats/min, blood pressure 130/80 mmHg, body temperature 36.5 ◦C, and respiratory rate 19 beats/min. There was a wide and fixed split of the second heart sound with the aortic component louder than the pulmonic component as well as a 2/6 ejection systolic murmur at the base There was no organomegaly or dependent edema. Transthoracic echocardiography (TTE) demonstrated the 16 mm ASD with small anterior rim and floppy posteror rim, She was advised percutaneous closure of the ASD. Preprocedural ultrasonogram scan of femoral nerve was obtained and femoral nerve visualized. Under strict aseptic precautions and ultrasound guidance, FNB was done using 1% lignocaine 15ml. Femoral nerve dermatome level sensory block was achieved in 10 minutes. Patient was shifted to cathlab for ASD device closure. No local anaesthesia was administered. The ASD was closed using 20mm device introduced through 12 Fr Mullins sheath without the need for sedation and additional local anaesthetics. Patient was comfortable throughout the procedure and did not vince with pain as is often the case during such procedures. The post procedure recovery was uneventful and she was discharged home the next day

Femoral Nerve Block (FNB)

Introduction

Peripheral nerve blocks inhibit the propagation of impulses in nerve terminals to inhibit the perception of pain by the cerebral cortex.

Local anaesthetics will temporarily block the transmission of pain.

The onset, duration, density, and spread of the nerve block may be influenced by the type of local anaesthetic given, concentration, and volume.

The FNB anesthetizes the femoral nerve distribution and is utilized for anterior thigh and knee procedures.

It can provide effective analgesia with less opioid intake, which consequently reduces the adverse effects from opioid consumption, and promote earlier hospital discharge.

Objectives

Describe the technique of an FNB
Review the complications of an FNB.
Advantages of using an FNB in a patient with low cardiovascular reserve and reduce the use of sedatives & analgesics.
Summarize the indications of an FNB.
Outline factors affecting the performance and improvement for outcomes of peripheral nerve blocks that require collaboration from all members of the medical team.

Anatomy and Physiology

The femoral nerve is among the largest branches of the lumbar plexus. The femoral nerve arises from the ventral rami of the L2, L3, and L4 spinal nerves, and enters the femoral triangle inferior to the inguinal ligament. The femoral nerve is the most lateral of the structures within the triangle, which also contains the femoral artery and femoral vein at its medial end.

The femoral nerve splits into anterior and posterior divisions that originate near the level of the circumflex artery. The anterior division gives rise to the medial femoral cutaneous nerve and innervates the sartorius muscle. The posterior division gives rise to the saphenous nerve and provides innervation to quadriceps femoris muscle. In addition to motor innervation, the femoral nerve provides sensation to the anterior thigh and knee and the medial lower extremity below the knee.

Indications

An FNB is usually indicated for procedures on the anterior aspect of the thigh.

FNB is also useful for analgesia in femoral neck fractures, femur fractures, SSG and patellar injuries. Femoral nerve block may be utilized alone or as part of a multi-modal pain management plan.

Contraindications

Absolute contraindications include patient refusal, inability to cooperate, and severe allergy to local anaesthetic agents. Relative contraindications include current infection at the site of local injection, patients on anticoagulation and antithrombotic medications, and patients with bleeding disorders. The physician should discuss the possibility of further nerve damage in patients with pre-existing nerve damage or those who may be susceptible to nerve injury (such as severe diabetes, trauma to nerves etc)

Equipment’s

Proper equipment is necessary for the femoral nerve block procedure. Sterile protocol with antiseptic solution (such as chlorhexidine scrub), sterile gloves, face mask, and hospital cap, should be maintained. A 20- or 22-gauge, 50- to 100-mm, short-bevel, insulated needle (that may be stimulating and/or echogenic), lidocaine 1% with a 25-gauge needle to anesthetize at the insertion site, and 20 mL syringe for local anaesthetic would be part of a standard nerve block kit. For an ultrasound-guided technique, an ultrasound machine with a linear transducer, sterile ultrasound probe cover, insulated needle, and ultrasound gel are all requirements. Local anaesthetic options may include long-acting amide agents, such as bupivacaine 0.5%, levobupivacaine 0.5%, or ropivacaine 0.5%, or intermediate-acting amide agents, such as mepivacaine 0.5% or lidocaine 0.5%. trauma to nerves, etc.

Preparation

The provider obtains informed consent in accordance with hospital policy. Importantly, a motor and sensory exam should take place, and any pre-existing neurological damage documented.

Before the start of the procedure, the following American Society of Anaesthesiology (ASA) standard monitors should be placed on the patient: pulse oximetry, continuous electrocardiography, and blood pressure (intermittent every 3 to 5 minutes or continuous monitoring). Reliable intravenous access and intravenous fluids should be confirmed. There should be immediate availability of oxygen, resuscitation equipment, and medications. A 20% lipid emulsion should be readily accessible in case of local anaesthetic toxicity.

The patient should be in the proper position before femoral nerve placement. The patient should be supine. The correct lower limb should be straightened, slightly abducted, and externally rotated.

The pannus may require additional retraction to better expose the groin area.

Lastly, a Time Out is strongly recommended prior to the start of the procedure for final confirmation. Light sedation may be administered at the direction of the proceduralist based on institutional policy.

Technique or Treatment

Ultrasound-Guided Technique

The femoral artery and vein are medial to the femoral nerve at the level of the inguinal ligament. When using ultrasound, the transducer is placed transversely at the inguinal crease, and the femoral vessels are located. If multiple arteries are present (i.e., superficial and deep femoral arteries), then slide the probe proximally until only the common femoral artery is visualized along with its associated femoral vein. Immediately lateral to the femoral vessels, the femoral nerve classically appears as a hyperechoic wedge or ovoid structure. The femoral nerve is superficial to the iliopsoas muscle group; and it is deep to the fascia lata and fascia iliaca, respectively.

Once the femoral nerve and relevant neighbouring structures have been identified, a lidocaine wheal is administered before the block needle insertion into the tissue, and the needle tip is advanced below the fascia iliaca towards the femoral nerve. Either an in-plane or out-of-plane approach may be used, depending on the proceduralist’s preference. Confirming negative aspiration for blood is recommended before injection to avoid intravascular injection. The ultrasound monitor will show the spreading of local injection around the nerve. [10] Caution is necessary with unusually high injection pressure or nerve expansion with injection, which may indicate intraneural injection. [11]

Complications

There are always risks involved when performing a peripheral nerve bock. The following are complications that can result: nerve injury, allergic reaction, hematoma, infection, and local anaesthetic systemic toxicity. Also, patients should understand the risk of the nerve block not working successfully, and other forms of analgesia should be available. There is a small risk of temporary or permanent nerve injury, which can be caused by direct needle injury or intraneural injection. Given the possibility of complications, resuscitation equipment must be nearby in the event of local anaesthetic systemic toxicity.

A 20% lipid emulsion administration is effective for local anaesthetic toxicity. A bolus dose of 1.5 mL/kg based on the lean body mass of lipid emulsion should be given over 1 minute and followed by an infusion of 0.25 mL/kg/min. This continuous infusion should continue until reaching hemodynamic stability. If hemodynamic stability is not obtained, then another bolus of 1.5 mL/kg (for a maximum of two total doses of 20% lipid emulsion), followed by a continuous infusion at the increased dose of 0.5 mL/kg/min should be considered. The 10% lipid emulsion in propofol should never be used as an alternative source for lipid emulsion therapy.

Clinical significance

An FNB includes motor and sensory nerves. Patients will exhibit difficulty with mobility due to the weakness of the quadriceps muscle. Mitigation of this motor weakness is achievable by using a reduced concentration of local anaesthetics. Importantly, patients should not be ambulating without assistance following femoral nerve block as they may be at risk for falling.

Fig (1): USG image depicting femoral nerve lateral to femoral artery beneath the fascia iliaca

Fig (2): USG image depicting needle advancement inplane for femoral nerve block,

Fig (3): USG image post local anaesthetic administration

Fig (4): Picture depicting 14 Fr sheath in right femoral vein.

References

Cousins and Bridenbaugh’s Neural Blockade in Clinical Anesthesia and Pain Medicine [Internet]. [cited 2025 May 8]. Available from:
Elsevier Asia Bookstore [Internet]. [cited 2025 May 8]. Miller’s Anesthesia, 2-Volume Set: 10th edition | Edited by Michael A. Gropper | ISBN: 9780323935920. Available from:
Hohmann E. Editorial Commentary: Femoral Nerve Block: Don’t Kill the Motor Branch. Arthroscopy. 2020 Jul;36(7):1981–2.
Re M, Blanco J, Gómez de Segura IA. Ultrasound-Guided Nerve Block Anesthesia. Vet Clin North Am Food Anim Pract. 2016 Mar;32(1):133–47.

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Femoral nerve block to facilitate painless device closure of atrial septal defect