JOURNAL OF ANESTHESIA AND PERIOPERATIVE CARE (ISSN:2732-4796)

Background: Femoral vein cannulation can be routine during major surgery, it is safe, easy and very usual in children undergoing cardiac surgery. It has a low insertion-related complication rate. This study compared ultrasound (US) guided cannulation of the femoral vein in infants with the traditional anatomical landmark guided technique in neonates and infant undergoing cardiac surgery for congenital heart disease.

Methods: This study was carried out on forty infants and neonates with mean age was 18 months (7 days-6 years). The mean weight was 8 kg (2.5 kg-20 kg), who had been prepared for cardiac surgery for congenital heart disease under general anesthesia. Patients were randomized into two equal groups (20 patients in each group): Group (І) where the femoral vein cannulation was guided by anatomical landmarks in optimally positioned patients, Group (ІІ) where femoral vein cannulation was guided ultra soundly.

Results: As regards success of procedure 12 cases in Group І, but in all cases in Group II. Higher needle passes number were noted in Group І compared to Group ІІ (3 (1-8) vs. 1 (1-3); p=0.001). Achieving of first pass success was in 8 cases in Group І and in 18 cases in Group ІІ. Cannulation time completed significantly shorter in Group II compared to Group І (205 (125-650) vs. 350 (135-1600) seconds; p=0.02). Arterial puncture is occurred in three cases in Group І while no complications occurred in Group ІІ.

Conclusions: Ultrasound guided techniques for femoral vein cannulation in critically ill pediatric patients is safe, effective and efficient. This approach had a high success rate, and was associated with zero complications in our setting.  

Congenital; Heart; Femoral vein; Neonates; Ultrasonic

In children with congenital heart disease undergoing cardiac surgery the femoral vein is an important site of cannulation particularly during cardiac catheterization and anesthesia [1,2]. Although infections and thrombosis were reported to be the long term complications of the femoral line, but there is no fear of hemothorax or pneumothorax which may occur during internal jagular or subclavian vein cannulation [3]. Femoral lines provides the advantages of easy access without interference with airway management and resuscitation efforts in pediatric patients during cardiac resuscitation [2,3].

Experienced anesthesiologists’ adept at femoral vein cannulation through landmark based approach in neonates and infant undergoing congenital cardiac surgery for congenital heart disease, may be wary of the US as they believe that this may take a longer duration and indeed no each ward will have a handheld ultrasound [3,4]. However nowadays it is practically and important to think in finding the ultrasound machine in pediatric cardiac intensive care for helping managing the critically ill pediatric patients during an emergency, where there is a necessity to insert a central line quickly by US guided technique as it is less time consuming [4,5]. However, a study done by the author and his colleagues [4] in 2012, clearly shown that US guided femoral vein cannulation can result in shorter cannulation times and success rate than anatomical landmark based techniques in children with nine to ten age group with no complications [4,5]. Femoral artery puncture and pricking of the head of the femur are the most common complication which may occurred in neonates and infants age group [1-3]. As it was evident that variations in anatomy related mainly to age and it is may not be obvious externally (but may be seen with US) [1-4].

The purpose of this study was to compare the ultrasound guided femoral vein cannulation in neonates and infant undergoing congenital cardiac surgery for congenital heart disease with the traditional anatomical landmark guided technique as regard to success rate and time of cannulation.

After approval by the institutional ethical committee, written informed consent was signed by the parents of the neonates and infants. Forty infants and neonates with mean age was 18 months (7 days-6 years). The mean weight was 8 kg (2.5 kg-20 kg), who had been prepared for cardiac surgery for congenital heart disease under general anesthesia. Patients were randomized into two equal groups (20 patients in each group). To indicate the group to which each infant was assigned randomization numbers were placed into sealed envelopes, which were opened by a chief nurse who was not participating in the study or in the patients’ care.

Exclusion criteria were as follows: previous catheterization of the femoral vein. Refusal by the parents, infection at the inguinal region, coagulopathy and individuals with congenital anomalies in the hip region.

After pre-medication with 0.1 mg/kg atropine (intramuscular route), general anesthesia was induced with sevoflurane in 100% O₂ ; and atracrium (0.5 mg/kg, intravenous route) was administered to facilitate endotracheal intubation and controlled ventilation (10 ml/Kg). All patients were placed in the 10° reverse Trendelenburg position, with external rotation of the hip and 60° abduction of the leg.

In Group І, femoral vein cannulation at the inguinal crease was guided by external anatomical landmark. After placing the patient in the optimum position, with the inguinal area adequately exposed to allow for identification of anatomic landmarks, the relevant right femoral region was painted with povidone-iodine and sterile drapes were positioned so as to isolate the femoral area. After donning gown, mask, cap, and sterile gloves, the surface landmarks were identified by palpation by the operator. Specifically, the position of the inguinal ligament, as well as pulsations of the femoral artery, was first identified. A point approximately 1 cm below the inguinal ligament and 0.5-1 cm medial to the femoral arterial pulsation was pinpointed at which a 20-gauge needle was inserted through the skin at a 45° angle, in the direction of the umbilicus, and parallel to the arterial pulsation. This process was repeated until venous flow was adequate.

In group ІІ, femoral vein cannulation was guided by ultrasonography at the inguinal crease, with the hip and leg in the same position as in Group I. The ultrasonography equipment used was a SonoSite 180 PLUS with an L25/10-5 MHz linear array ultrasonic transducer (SonoSite, Inc., Bothell, WA); the latter was prepared and sterilized by covering the sheath with an OPSITE over the length of the transducer and the time taken for preparing was not calculated in the total time of the procedure. The femoral artery and vein were identified by scanning the inguinal area immediately distal to the inguinal ligament, and the vein centered on the screen using an out-of-plane technique; the probe was held perpendicular to the patient’s skin, in the operator’s left hand. A 20 G needle was inserted with the right hand angled at 45⁰ and its position in relation to the vein was adjusted based on tissue movement visualized on the screen. After successful vein puncture, the US probe was kept aside and the left hand was used to stabilize the cannula in position. The guide wire was then passed through the cannula into the vein and the cannula removed.

In all patients, the 20-gauge cannula allowed easy insertion of the guide wire, which was followed by insertion of a 5.5 F pediatric multi lumen CVC kit (Arrow; Arrow International, Inc., Reading, PA), using the Seldinger technique.

A decision to shift from the right to the left side was made whenever the femoral pulse was lost, in Group І, or whenever the ultrasonography image was lost, in Group II; however, shifting to the opposite side was considered a failure of insertion. The cannula was redirected or the maneuver repeated until adequate venous flow was obtained. Every time the maneuver was repeated, it was considered a new needle pass, and the total number of needle passes required for successful cannulation was recorded for both groups. Success was defined as femoral cannulation within 3 passes.

No time limit was set for the procedure. The time required for successful wire insertion was calculated from the time that the skin was penetrated until the guide wire had been successfully inserted, as described previously. The time from insertion of the wire to complete cannulation using the triple-lumen catheter was also recorded. The total time for cannulation was then calculated as the sum of both recorded times.

The number of needle passes, the success rate, the number of cases with success achieved within the first pass, the time taken for the procedure, and the incidence of complications were noted. In addition, we recorded the number of arterial punctures and whether any significant hematoma occurred.

The sample size required for the study was determined based on the primary outcome measure. The primary outcome measures of this study were time and the number of attempts required for successful cannulation, secondary outcomes include first attempt success and hematoma formation. Power analysis identified that 40 patients per group were required to detect a 35% difference between groups, with a power of 80%.

Student’s t-test was used to compare demographic data, and Fisher’s exact test was used to compare categorical variables. p<0.05 was considered statistically significant.

Patient’s characteristics are recorded in Table 1. There was no significant difference between the 2 groups.

The procedure was successful in 12 cases in Group I, but in Group ІІ, all cases were successfully cannulated. The number of needle passes was higher in Group І compared to Group ІІ (3 (1-8) vs. 1 (1-3); (p=0.001). First-pass success was achieved in 8 cases in Group І and in 18 cases in Group ІI (p=0.001). Time to successful wire insertion (290 (72-1500) and 113 (64-587) (p=0.02) and total time taken to complete cannulation was significantly short in group II compared to Group І, being 350 (135-1600) s and 205 (125-650) s (p=0.02) in Groups I and II, respectively (Table 2).

In Group І, 3 cases showed arterial puncture and hematoma formation, but no cases of arterial puncture were found in Group II.

Real-time ultrasound guidance during central line insertion improving patient safety practices [5] and it has been strongly advocated as a standard of care by the National Institute for Clinical Excellence in the United Kingdom [6,7]. Publications involving the use of ultrasound-guided CVC in children mostly involved cannulation via the internal jugular vein [6,8,9]. Nonetheless, despite evidencebased support for ultrasound during CVC, one survey showed that the approach still has limitations [10], and most of the evidence supporting the use of ultrasound guidance over the landmark-guided technique involves studies done in adults [6].

Although in a previous study done by the author and his colleagues from five years ago [4] they found that ultrasound-guided cannulation of the femoral vein offers superior results to that of cannulation guided by an anatomical landmark in nine to ten age group as regard to higher success rates, shorter time to cannulation and was associated with no complications, but still evidence supporting the use of ultrasound has been considered less compelling in children [11].

In this study, we compared the ultrasound guided femoral vein cannulation in neonates and infant undergoing congenital cardiac surgery for congenital heart disease with the traditional anatomical landmark guided technique as regard to success rate, time of cannulation and related complications. We found that US guided cannulation in neonates and infant undergoing congenital cardiac surgery for congenital heart disease resulted in higher success rates, shorter time to cannulation and was associated with no complications.

There is limited literature on the two guidance approaches for cannulation of the femoral vein in children [12]. However, a recent study and an accompanying editorial signifies the increasing importance and safety of this technique in children [13,14].

We positioned the patient in a reverse trendelenberg position with external rotation and a 600 abduction of the leg for femoral vein cannulation. This position has been shown to increase the diameter of the femoral vein as well as minimize overlap between the femoral artery and vein [4].

The position of the hip and leg used in our study results in least overlap of the femoral vein by the femoral artery and maximum diameter of the vessels. Previous studies have shown that overlapping of the femoral vein by the femoral artery occurs in about 12% of cases, but other studies have shown that this overlapping may occur in more than 50% of cases [2].

The overlap between artery and vein may be partial, or complete; differences in the definition of overlap may account for the different percentages of overlap among the studies [2]. According to Warkentine et al. [15], 8% of pediatric patients manifested complete overlap of the femoral vein by the femoral artery. Partial overlap in the region immediately distal to the inguinal ligament was demonstrated in 45% of cases [15].

A study by Hopkins et al. [15], revealed that a variable relationship exists between the femoral artery and vein in both straight leg and frog leg position. However, the diameter of the veins increases with frog leg position. The primary outcome of our studies (the previous [4] and present) is typically the time needed to achieve successful cannulation of the femoral vein the critically ill pediatric patients (neonates, infants and child) during an emergency, secondary outcomes include the success rate, the number of needle passes required for successful cannulation, the number of successful cannulations on first needle pass, and the incidence of arterial puncture and hematoma [4-13]. 

The main operators were pediatric cardiac anesthesiologist who had acquired basic training in echocardiography while rotating in the pediatric cardiology department. In addition, he attended a critical care ultrasound course, which included hands-on training in ultrasoundguided vascular access and had one or more years of experience in agree with our results. The study done by Verghese et al. [16] who compared the use of real-time 2-dimensional ultrasound or landmarkguidance in children undergoing internal jugular vein cannulation performed by inexperienced operators and found that ultrasoundguidance improved overall success, speed, and incidence of carotid puncture [16]. Also in a more recent study, in which experienced cardiac anesthesiologists performed cannulation of the internal jugular vein in children, reported that the landmark-guided technique was more often successful, and involved fewer arterial punctures, than the ultrasound-guided technique [9]. An interesting observation in a pediatric intensive care showed that the time needed for successful CVC was less when using ultrasound rather than landmark guidance, but only when the operators were residents, and not with experienced operators [17], as repeated attempts at cannulation may result in thrombosis or compression of the vein by the surrounding hematoma, reducing the chances of subsequent successful cannulation.

Our study hadn’t detected a significant difference in the incidence of femoral artery puncture between the 2 guidance techniques. However, Iwashima et al. [12] previously demonstrated femoral artery puncture occurring in 7% of an ultrasound-guided group, compared to 31.8% of a landmark-guided group (p<0.01). Moreover, visualization via ultrasound also helps to avoid pricking the head of the femur, which introduces the possibility of inducing a vascular necrosis, especially in neonates [3].

Other studies have employed a different definition of time to successful cannulation. Asheim et al. [18] reported the time to aspiration of blood as the time to successful cannulation. But the time to successful guide wire insertion as used in our study was considered more clinically useful, because identification of venous blood flow through the cannula is not always an indication that the guide wire will be successfully inserted, especially in young children [19]. For instance. Grebenik et al. [11], described the inability to insert the guide wire, despite successfully aspirating venous blood, as the most common problem during internal jugular cannulation in children [9,11].

Ultrasound guided femoral vein cannulation in neonates and infant undergoing congenital cardiac surgery has greater success rate, lesser number of attempts, and less complications is superior to land mark based approach. 

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