Ultrasound-guided cannulation of the superficial femoral vein for central venous access

Introduction

Central venous access is usually achieved by ultrasound-guided puncture/cannulation of deep veins of the cervico-thoracic area (CICC = centrally inserted central catheters) or of the arm (PICC = peripherally inserted central catheters), and the tip is located either in the superior vena cava (SVC) or in the right atrium (RA), or more precisely—as recommended by most recent guidelines^1,2—in proximity of the SVC/RA junction.

There are some patients, though, in whom a cervico-thoracic or brachial approach may be not feasible or even contraindicated. Compression or infiltration of SVC, large mediastinal tumors, bilateral breast cancers, lung or esophageal cancer with mediastinal infiltration, etc., are well known clinical conditions potentially associated with difficult or impossible progression of the catheter into the SVC. In these situations, central venous access can alternatively be obtained by cannulation of the femoral vein and placement of the catheter tip in the inferior vena cava (IVC) or at the IVC/RA^3,4: such type of central access may be defined as FICC (femorally inserted central catheter).

Until recently, FICCs have been inserted almost exclusively by puncture/cannulation of the common femoral vein (CFV) in the inguinal groove, with the exit site at the groin. This approach is burdened with a high risk of catheter-related infection (mainly due to the high bacterial contamination of this skin area) and of catheter-related venous thrombosis (due to many factors, but mainly to the instability of the catheter when the exit site is in a flexion area).^5,6 To overcome these complications, in the last decade, many centers have adopted the technique of tunneling the catheter so to move the exit site from the groin downward to mid-thigh, or upward to the abdomen.^7–12

Another interesting strategy to achieve an exit site at mid-thigh, without tunneling, is the direct puncture/cannulation of the superficial femoral vein (SFV), recently described by Wan et al. ¹³ and by Zhao et al. ¹⁴ These two recent clinical studies suggest that such technique is feasible and safe, being associated with a rate of complications similar to PICCs with exit site at midarm.

In these clinical studies, the superficial femoral vein (SFV) is defined (as in most anatomy textbooks) ¹⁵ as that portion of femoral vein which begins after the popliteal vein, in the adductor canal (Hunter’s canal), and ends below the inguinal groove, merging with the deep femoral vein into the common femoral vein (CFV). As such, it is the main vein of the thigh. This definition is still maintained in some textbooks and articles of ultrasound anatomy, ¹⁶ while some textbooks of phlebology and vascular surgery name it simply “femoral vein.” We will keep the term ‘superficial femoral vein’ so to differentiate clearly this venipuncture from the traditional venipuncture of the common femoral vein (CFV). Still, one must consider that the “superficial” femoral vein is actually a deep vein, since it is located at more than 1 cm (typically, 3–6 cm) from the skin surface.

In this study, we report our 6-month experience of non-tunneled FICCs inserted by direct ultrasound-guided puncture/cannulation of the SFV.

Methods

We have reviewed retrospectively all the FICCs recently inserted via SFV puncture by our Vascular Access Team, a multi-professional, multi-disciplinary team which inserts approximately 7000 central lines per year (including short, medium, and long term central venous access devices) in our University Hospital. Though our experience with SFV puncture started approximately 1 year ago, we have considered only the catheters inserted in the last 6 months (from June 1st, 2020 to December 31st, 2020).

According to our hospital policies, all central line insertions, both in outpatients and in hospitalized patients, are recorded in a computer-based archive; all relevant catheter-related complications are also reported to our Team and managed by our Team. The technique of central venous access device insertion is standardized and described in appropriate insertion bundles, recommended by our hospital policies.

In particular, our insertion bundle for FICC placement includes the following steps: systematic pre-procedural assessment of the deep veins of the groin and the thigh, according to the RaFeVA protocol (Rapid Femoral Vein Assessment), ¹⁶ for an appropriate choice of the best venous approach and a proper planning of the exit site; aseptic technique (hand hygiene, skin antisepsis with 2% chlorhexidine in alcohol, maximal barrier precautions); ultrasound-guided puncture/cannulation; ultrasound-based tip navigation; ultrasound-based or ECG-based tip location (if tip location is planned at the IVC/RA junction); sutureless stabilization of the catheter; protection of the exit site with cyanoacrylate glue and semipermeable transparent membrane.

All FICC insertions via the SFV were performed by six different operators of our team, using the same technique.

All catheters were inserted at bedside, using either a wireless portable ultrasound device (Cerbero, ATL; linear transducer: 7.5–10 MHz) or a standard ultrasound device (Edge II or NanoMaxx, SonoSite-Fuji; linear transducer, 6–13 MHz). Most patients were in supine position or in a half-sitting position; the leg was preferably placed in slight abduction, though this was not always possible, considering that some patients had obligatory postures due to paresis or muscle spasticity.

After obtaining informed consent, we assessed the patency and the caliber of the CFV and of the SFV, using the RaFeVA protocol. The best site for cannulation of the SFV was identified at mid-thigh or in the distal third of the thigh (Figure 1), as long as its inner diameter was appropriate for the catheter size (4 Fr or 5 Fr catheters requiring respectively 4 or 5 mm veins). In all patients, pressure injectable polyurethane non-valved catheters (4 Fr single lumen or 5 Fr double lumen, 50–60 cm long) were used. Different catheter brands were adopted (Synergy CT, Healthline; ProPICC, Medcomp; Celsite PICC, BBraun).

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Figure 1.

Ultrasound visualization of right superficial femoral artery and right superficial femoral vein at mid-thigh, in short axis: the vein is placed below the artery, slightly lateral.

According to our hospital policies, the puncture/cannulation was performed after skin antisepsis with 2% chlorhexidine in 70% iso-propylic alcohol, using maximal barrier precautions (beret, mask, sterile gowns, and gloves, wide sterile drapes over the patient, sterile cover for the probe) (Figure 2). All procedures were performed using a specific and dedicated insertion pack. After skin infiltration with few ml of local anesthesia (7.5% ropivacaine) (Figure 3), the SFV was cannulated using real-time ultrasound guidance and micro-introducer technique (21G needle, floppy straight tip 0.018″ nitinol guide wire and micro-introducer-dilator) (Figure 4).

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Figure 2.

Operative field before puncture/cannulation of superficial femoral vein.

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Figure 3.

Visualization of the vein in short axis, using wireless probe.

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Figure 4.

Venipuncture with 21G needle.

When the SFV was located laterally or medially to the superficial femoral artery (SFA), a short axis visualization with “out-of-plane” puncture was adopted; when the SFV was located below the SFA, an oblique axis visualization with “in-plane” puncture was preferred.

After venipuncture, the vein was cannulated by the modified Seldinger technique (introduction of the guide wire into the needle, removal of the needle, placement of the micro-introducer-dilator over the guide wire, removal of the guide wire and of the dilator, insertion of the catheter inside the micro-introducer).

If the tip had to be located in the mid-portion of the IVC, the catheter was trimmed according to a length estimation based on surface landmarks (from puncture site to the navel), so to have the tip approximately placed above the confluence of the iliac veins and below the renal veins. If hemodynamic monitoring was required, the tip of catheter was placed precisely in RA or at the IVC/RA junction using the intracavitary ECG method (IC-ECG) of tip location; in such cases, the catheter was trimmed according to a length estimation based on the distance between the puncture site and the third intercostal space on the parasternal border. At IC-ECG, the biphasic P wave corresponds to the midportion of the RA and the maximal negative P wave corresponds to the IVC/RA junction.^17–19 An additional 2–2.5 cm of catheter length were added to the landmark-based length estimation considering that all FICCs were secured by a subcutaneously anchorage device (SecurAcath, Interrad).^20,21

According to our hospital policies, after subcutaneously anchored securement, the exit site was sealed with cyano-acrylate glue and protected with a semipermeable transparent dressing (Figure 5).

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Figure 5.

Securement by subcutaneous anchorage + sealing with cyanoacrylate glue + protection with semipermeable transparent membrane.

All relevant data related to the insertion procedure were recorded, according to our hospital policies, and retrieved for this retrospective analysis. We have also retrieved information about relevant catheter-related complications from the database of our Team. In fact, all major catheter-related complications occurring during hospitalization (infection, venous thrombosis, catheter dislodgment, irreversible lumen occlusion) are reported and recorded. The diagnosis of catheter-related blood stream infection was based on paired cultures (from the lumen of the catheter and from the peripheral blood), according to the method of delayed time to positivity (DTP) ²² ; the diagnosis of catheter-related venous thrombosis was based on ultrasound examination of the veins, performed only in case of local signs or symptoms suggestive of venous thrombosis.

This retrospective study was carried out according the STROBE checklist for retrospective cohort studies.

Results

Between June 1st, 2020, and December 31st, 2020, we inserted 98 non-tunneled FICCs using an ultrasound-guided approach to the superficial femoral vein (SFV).

Indications to FICC insertion included patients requiring central venous access but with absolute or relative contraindications to both CICC and PICC insertion:

Most patients were adults (n = 96) (mean age 70 years old, age range 40–90; 51 females and 45 males), while two patients were less than 18 years old (15 and 17 years old, both males).

We inserted 50 double lumen 5 Fr catheters (Figure 6), mainly in patients who were scheduled to stay in our hospital, and 48 single lumen 4 Fr catheters (Figure 7), mostly in patients candidate to long term facilities or candidate to chemotherapy.

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Figure 6.

Double lumen 5 Fr catheter in a hospitalized patient.

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Figure 7.

Single lumen 4 Fr catheter in a patient to be referred to nursing home.

All 5 Fr catheters were inserted in SFV with inner diameter equal or superior to 5 mm, and all 4 Fr catheters in SFV with inner diameter equal or superior to 4 mm. The mean diameter of SFV was 6 (range 4–8 mm), and the mean depth was 4 cm from the skin (range 3–6 cm).

As regards to the venipuncture, the short axis out of plane technique was most commonly used (52 pts); the oblique axis in plane technique was adopted in 46 pts.

The vast majority of insertion were on the right thigh (81%): the left SFV was accessed mainly in patients with paresis or previous femoral venous thrombosis of the right lower limb.

In 94 patients, the tip of the FICC was located in the midportion of the IVC; in two adult patients and in two pediatrics, hemodynamic monitoring was required, so that the tip was located in RA, or at the IVC/RA junction using IC-ECG.

At the end of the procedure, the exit site of catheter was in the middle third of the thigh in 52 pts and in the distal third of the thigh in 46 pts.

Table 1 summarized the main characteristics of the FICCs inserted in our patients.

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Table 1.

Patients and catheters.

	Intra-hospital use	Extra-hospital use
Number of patients	52	46
Sex
- Male > 18 years old	25	20
- Male < 18 years old	2	–
- Female	25	26
Catheter size/lumens
- 5 Fr double lumen	44	6
- 4 Fr single lumen	8	40
Tip position
- Right atrium	4	–
- Mid-portion of IVC	48	46
Exit site location
- Thigh, middle third	32	20
- Thigh, distal third	20	26

All procedures were successful. Most veins (95%) were punctured at the first attempt. No major immediate/early complication was recorded. There were three minor immediate/early complications:

The long-term follow-up was not possible in all cases, as late complications potentially occurring in the patients referred to nursing facilities (n = 27, 27.5%) were not consistently reported to our team. Though, in the patients who stayed hospitalized (n = 71, 72.5% of cases), no major late catheter-related complications were reported: in particular, we had no catheter-related blood stream infection, no irreversible lumen occlusion, and no catheter-related venous thrombosis. There was only one case of accidental dislodgment, in an agitated, non-collaborative patient (though the catheter was secured by subcutaneous anchorage). In one patient, there was a suspect of asymptomatic catheter-related venous thrombosis, which was finally diagnosed as a fibroblastic sleeve at closer ultrasound examination. In one patient with suspected catheter-related infection, paired blood cultures showed a catheter colonization (peripheral blood culture was negative, while a Staph.hominis was isolated by the catheter blood sample).

In this group of 71 hospitalized patients, the mean duration of the central line was 35 days (range 1–123 days), with only three unscheduled removals, as described above (one guide-wire replacement at day 1 because of malfunction; one catheter removed because colonized; one catheter lost for accidental dislodgment).

Discussion

Femoral Inserted Central Catheters (FICC) are a useful alternative when the SVC is not accessible. The use of FICCs was first described in patients with mediastinal tumors, bilateral breast cancer, lung cancer with mediastinal infiltration, or lymphoma with SVC compression.^3,4,7 Traditionally, the inferior vena cava approach is performed through common femoral vein cannulation at the groin site. However, this approach, because of the exit site in the groin area, has an elevated risk of late catheter-related complications, in particular infection and thrombosis.^5,6

In the last decade, for the purpose of reducing the risk of catheter related blood stream infection (CRBSI), the tunneling technique has been introduced to move the exit site away from the groin zone. This technique consists in creating a long subcutaneous tunnel from the puncture site in the groin zone to the mid-thigh or up to the abdomen.^7–12

In the last years, the direct cannulation of the superficial femoral vein in oncologic patients has been described by Wan et al. ¹³ and by Zhao et al. ¹⁴ The superficial femoral vein has been considered in the last decade for formation of fistulas for hemodialysis,^23,24 but its cannulation for infusion purposes had never been described before.

The cannulation technique described by Wan and by Zhao consists in the ultrasound-guided puncture (short axis, out of plane) of the superficial femoral vein at mid-thigh, so that the exit site is 10–20 cm away from the groin. In both studies, the procedure was performed mostly in patients with superior vena cava syndrome, mediastinal tumors, bilateral breast cancer, or renal failure. In a non-randomized comparison with PICCs, both studies reported less risk of dislodgment, of primary malposition and of infection, a similar duration of the line, as well a similar risk of thrombosis, bleeding, and skin problems. Ostroff et al. ²⁵ have reported seven cases of cannulation of the superficial femoral vein in hospitalized non-oncologic patients, for a duration of less than 4 weeks, with no major complication (no catheter-related infection and no catheter-related thrombosis).

To our knowledge, our study is the first to describe SFV cannulation also in agitated, delirious patients and in patients with severe physical disabilities candidate to long term facilities. Furthermore, it is the first study to describe the ultrasound-guided approach to SFV with visualization in oblique axis and in-plane puncture.

In our cohort of patients, 41% were delirious, agitated patients with previous loss of PICCs and CICCs. Delirium is frequent in aged hospitalized patients and is associated with high morbidity and mortality.^26,27 Causes of delirium in our patients were posttraumatic syndromes, metabolic disorders (hyponatremia) and cerebral ischemic syndromes. Agitated patients may pull away every indwelling device they can reach (such as nasogastric or jejunal tubes, urinary, and intravenous catheters), sometimes even if restrained. ⁹ Subcutaneous anchored securement^20,21 may reduce but not completely avoid the risk of accidental dislodgment in this population of patients. We decided to use the SFV approach in confused, agitated patients after repeated episodes of removal of CICCs and PICCs, even if such catheters were secured by subcutaneous anchorage. In such patients, we assumed that the exit site in the inferior third of the thigh—sometimes very close to the knee and covered with elastic band—would make more difficult for the patients to reach the catheter and pull it away (Figure 7). In this area of the thigh, the SFV is particularly deep and typically located below the artery, so that we had to use an oblique axis/in-plane approach and a longer micro-introducer-dilator (7 cm rather than 5 cm).

Prevision of hospital discharge for referral to a long-term health care facility is a frequent indication to venous access: 27.5% of the patients included in our study needed a central line because candidate to long term facilities. Many of these patients had physical disabilities such as mono-lateral paresis, tetraplegia spastic, or progressive paresis due to amyotrophic lateral sclerosis. SFV cannulation was preferred because of the presence of tracheostomy, and/or inaccessibility of arm veins, and/or high risk of contamination of the infraclavicular skin area by oral or tracheal secretions. One patient with amyotrophic lateral sclerosis had bilateral arms paralysis but was still autonomous in walking; though, he was very afraid of cervico-thoracic puncture and he preferred a femoral approach.

As previously described in other studies, ¹³ superior vena cava syndrome, hematologic malignancy and thyroid cancers with mediastinal infiltration were indication to SFV cannulation also in our study (in 19.3% of patients). Most of these cancer patients requires a venous access for chemotherapy and many of them had coagulation and platelet disorders, which might have contraindicated the maneuver of tunneling the catheter.

Other indications—such as the presence of dialysis catheter in the right jugular vein and pacemaker in the left subclavian vein (two patients of our study) and dialysis fistulas in chronic renal failure patients (two patients)—has already been described by Zhao et al. ¹⁴

Severe vasculopathy and no possibility of PICC or CICC insertion because of repeated previous venous cannulations and very small veins in a patient with both legs amputated (mid-thigh in the right leg and below the knee on the left side: the SFV was obviously cannulated on the left thigh) was another peculiar indication in our experience.

Liver failure with severe low platelet count (<5000 per microliter) and coagulopathy (INR > 3) in four patients (5%) with small arm veins (<4 mm) was another indication to SFV approach. Low platelet count and severe coagulopathy may be relative contraindications to cannulation of cervical/thoracic central veins for CICC insertion. ²⁸

Another indication to SFV was respiratory failure in two septic patients with helmet, both with severe coagulopathy. The presence of the rubber collar of the helmet is associated with difficult CICC insertion and the underarm straps tight around the axilla may increase the risk of thrombosis, in particular after cannulation of arm veins. ²⁹ The use of FICC has been advocated in COVID patients with helmet for non-invasive ventilation, ³⁰ but to our knowledge we are the first to report a SFV approach in patients with helmet.

As regards the choice of the device, since the caliber of SFV ranges typically between 5 and 8 mm, it was possible to use either single lumen 4 Fr or double lumen 5 Fr catheters without increasing the risk of thrombosis; 4 Fr catheters were preferred, and double lumen 5 Fr catheters were used only if necessary, mostly in hospitalized patients with multiple simultaneous infusions.

At mid-thigh, the SFV usually lies in a slight medial position to the artery, and the depth of the vein is approximately 3–5 cm from the skin: therefore, the easiest approach is a short axis visualization with out-of-plane puncture. More distally, in the inferior third of the thigh, at 5–10 cm from the knee, the SFV is usually located below the artery, and in a deeper position (>5 cm): thus, in this zone we preferred an oblique axis visualization with in-plane puncture, and we were forced to use a longer micro-introducer-dilator (7 cm).

In our retrospective analysis, the incidence of immediate, early and late complications was very low, and all complications were mild and not associated with any morbidity and mortality. It is interesting to note that CRBSI and symptomatic catheter-related thrombosis did not occur, at least in those patients (n = 71; 72.5%) who used the device during hospitalization. This might confirm that the location of the exit site plays an important role in determining the risk of both infection and thrombosis: in the hospitalized, bedridden patient the exit site at mid-thigh or in the lower third of the thigh may be associated with less risk of bacterial contamination and of catheter instability, if compared to the exit site at the groin or at the neck.

The limitations of our study are the following:

In conclusion, our experience suggests that the approach to the superficial femoral vein may open new perspectives in the area of femorally inserted central catheters (FICC): it is a completely safe technique, which is not associated with any potential risk of severe insertion-related complication (in this, it is similar to PICC insertion).

If compared to non-tunneled FICCs inserted in the CFV, FICCs inserted in the SFV have the great advantage of a better exit site; also, contrary to tunneled FICCs, they can be inserted also in patients with low platelet count or coagulation disorders, without any risk of relevant local complications.