Study on the Application of Accelerated Seldinger Technique for Mini Midline Catheter Insertion in Bariatric and Metabolic Surgery

LI Xuejuan¹, LIU Cuixiang¹, LI Haoyang², LIANG Rixiao¹, HU Jing¹, WEI Jianbao¹

Abstract

Objective: To evaluate the clinical effectiveness of the Accelerated Seldinger Technique (AST) for inserting mini midline catheters in patients undergoing bariatric and metabolic surgery.

Methods: A total of 110 patients admitted to the Bariatric and Metabolic Surgery Department of a tertiary hospital in Nanning from July 2023 to April 2024 were randomly assigned to a control group (n = 55) and an experimental group (n = 55). Both groups underwent ultrasound-guided catheter placement. The control group received midline catheter insertion using the modified Seldinger technique, while the experimental group received mini midline catheter insertion using the Accelerated Seldinger Technique. The catheterization procedure outcomes and catheter-related complications were compared between the two groups.

Results: The catheter dislodgement rate in the control group was significantly higher than that in the experimental group (P < 0.05). The total medical cost in the control group was also significantly higher than that of the experimental group (P < 0.05).

Conclusion: Mini midline catheter placement using the Accelerated Seldinger Technique is cost-effective, associated with a lower incidence of complications, and can reduce repeated venipuncture-related pain in bariatric and metabolic surgery patients. It is suitable for wider clinical application.

 

Keywords: Mini midline catheter; Midline catheter; Seldinger technique; Bariatric and metabolic surgery; Intravenous therapy

 

It is estimated that by 2030, the prevalence of overweight and obesity among adults in China will reach 70.5%, and obesity has become a major public health issue seriously affecting the health of the Chinese population. Relevant studies have predicted that obesity-related type 2 diabetes mellitus (T2DM) will affect more than 200 million individuals^[1]. Moreover, the impact of obesity on the cardiovascular system has been progressively increasing^[2]. Bariatric and metabolic surgery is currently recognized as the most effective treatment for obesity and related metabolic disorders^[3].

However, due to thick subcutaneous adipose tissue, potential vascular pathology, and poor superficial venous visualization in obese patients, venous access for daily infusion therapy and venous blood collection has become a clinical challenge. Under ultrasound guidance, the depth of large veins such as the basilic vein may reach 2–3 cm beneath the skin surface^[4]. Traditionally, central venous catheters (CVCs) have been used to meet the needs of infusion therapy and hemodynamic monitoring. However, CVCs are associated with risks such as pneumothorax, hemothorax, and higher catheter-related infection rates, and are not recommended for routine blood sampling.

With the advancement of intravenous therapy, peripherally inserted central catheters (PICCs) have been widely adopted, as they can meet treatment requirements, tolerate high-pressure contrast injection, and enable hemodynamic monitoring due to their specific lumen design^[4,5]. Nonetheless, PICCs also carry risks such as phlebitis, catheter malposition/dislodgement, catheter-related bloodstream infections, and venous thrombosis^[6–7], and some patients are unable to undergo real-time tip confirmation without imaging guidance, resulting in additional medical costs^[8].

In recent years, midline catheters have gained widespread clinical use due to their relatively simple insertion procedure and no need for imaging confirmation. The use of midline catheters in bariatric and metabolic surgery patients can meet infusion and blood sampling needs while reducing the risk of catheter-related complications^[9]. However, midline catheters still have limitations, such as higher cost and inability to tolerate high-pressure contrast injection, making them unsuitable for contrast-enhanced imaging tests.

Mini midline catheters, also known as short peripheral extended-dwell catheters, are inserted via superficial or deep veins in the forearm or upper arm, with the catheter tip located within the arm veins and not exceeding the axillary vein level^[10]. Common mini midline catheter specifications in China include 8–10 cm in length, 3–5 Fr (18–22 G), with flow rates ranging from 23 to 71 mL/min, and are primarily made of polyurethane. The integrated puncture-needle-catheter-guidewire system allows for faster and more convenient insertion, and certain models are designed to withstand high-pressure injections. Mini midline catheters have shown favorable outcomes in patients with malignancy, pancreatitis, and emergency conditions^[11–13], whereas research regarding their application in obese patients undergoing bariatric and metabolic surgery remains limited.

Therefore, this study included patients who underwent bariatric and metabolic surgery between July 2023 and April 2024 in a tertiary hospital in Nanning, comparing the perioperative outcomes of mini midline catheter placement vs. midline catheter placement, with the goal of reducing repeated venipuncture-related pain in this special population.

 

1. Participants and Methods

 

1.1 Study Population

According to previous literature, the incidence rates of adverse reactions in the experimental group and the control group were 4.65% and 30.23%, respectively^[4]. The sample size was calculated using PASS software, with a minimum requirement of 31 participants per group. Considering a 20% attrition rate, at least 38 participants were required for each group, resulting in a total sample size of 76 subjects to ensure methodological rigor.

Patients who underwent bariatric and metabolic surgery in the Bariatric and Metabolic Surgery Department of a tertiary hospital in Nanning from July 2023 to April 2024 were enrolled and randomly assigned using a random number table method into the control group (midline catheter group, n=55) and the experimental group (mini midline catheter group, n=55). A designated research coordinator was responsible for group allocation and was not involved in clinical intervention, ensuring allocation concealment.

The randomization procedure was as follows:

The coordinator first generated a random number table and corresponding allocation code. Patients were assigned based on parity of random numbers, with odd numbers allocated to one group and even numbers to the other. As patients were admitted at different times, the coordinator drew the next random number sequentially for each newly enrolled patient and assigned the patient according to the predefined mapping rule.

Inclusion criteria:

(1) Patients eligible for bariatric and metabolic surgery according to the 9th edition of Surgery published by People’s Medical Publishing House: BMI ≥ 35 kg/m², or BMI 27.5–34.9 kg/m² with poorly controlled type 2 diabetes mellitus despite lifestyle modification and pharmacological therapy, or with at least two other metabolic-related comorbidities^[14];

(2) Meeting indications for peripheral venous catheterization and suitable for peripheral venous therapy;

(3) Presence of suitable upper-limb vascular access confirmed by ultrasound and first-time venous catheter placement;

(4) Age ≥18 years, cognitively competent, able to understand study procedures, voluntarily consented, and demonstrated good compliance.

 

Exclusion criteria:

(1) History of two or more previous venous catheterizations;

(2) Severe mental disorders, cognitive impairment, or communication difficulties;

(3) Skin lesions at puncture sites, including scratches, ulceration, abrasions, or burns;

(4) Patients with serious comorbidities (such as severe cardiac, hepatic, or renal dysfunction, malignancy, respiratory failure) or in acute exacerbation phase.

 

Withdrawal criteria:

(1) Transfer to another hospital due to condition change or personal preference;

(2) Voluntary withdrawal during the study.

 

This study was approved by the Institutional Ethics Committee (Approval No.: KY2021-025). All participants were fully informed and signed written informed consent. During the study period, four patients in the experimental group withdrew, and three patients discontinued surgical treatment after catheter placement and were discharged. Ultimately, 55 patients were included in the control group, and 48 patients were included in the experimental group.

 

1.2 Methods

1.2.1 Catheterization Procedure

(1) Operators:

Catheter insertion was performed byspecialist nurses who had completedprovincial or national venous therapy certification and had≥3 years of clinical experience in vascular access management. Catheter assessment, maintenance, documentation, and monitoring were conducted by specialist nurses or nurses who had completed internal venous therapy competency training.

(2) Control Group:

A4 Fr single-lumen midline catheter with a proximal three-way valve, 30 cm in length (Shubeikang Medical Co.), was used. Ultrasound was applied for vascular assessment, prioritizing the basilic vein, followed by the cephalic or brachial vein. Catheterization was performed using amodified Seldinger technique under ultrasound guidance. The procedure steps were as follows:

1. The patient was positioned supine with the arm abducted at 90°.

2. Skin antisepsis was performed using75% ethanol followed by 0.5% povidone-iodine using the “forward–reverse–forward” technique within a20 × 20 cm sterile field, followed by sterile draping to establish maximal sterile barrier precautions.

3. The specialist nurse selected the introducer needle guide based on vessel depth. After venipuncture and blood return confirmation, the needle angle was lowered, and the guidewire was advanced. The introducer needle was removed, local anesthesia was administered, and a peel-away sheath was inserted following skin dilation. The catheter was advanced gently to the predetermined length through the sheath.

4. After confirming blood return, the catheter was flushed and locked with normal saline, connected to an extension line and infusion connector, and secured usingsterile transparent tension-free dressing.

(3) Experimental Group:

A4 Fr single-lumen, front-open, integrated mini-midline catheter with a length of10 cm (Haolang Medical Co.) was used. Vascular assessment and site selection were identical to the control group, ensuring thatat least two-thirds of the catheter length remained within the vessel[10]. Catheter insertion was performed using anaccelerated Seldinger technique under ultrasound guidance. Procedure steps were:

 

1. Patient positioning and sterile barrier precautions were identical to the control group.

2. The specialist nurse stabilized the ultrasound probe with the left hand, while using the right hand to hold the catheter introducer track with the thumb and middle finger, using the index finger to stabilize the peelable sheath. Needle angle was adjusted according to vessel depth. After venipuncture confirmation by blood return, needle angle was lowered, the probe was released, guidewire inserted, and catheter advanced slowly before removing the guidewire.

3. After connection with the extension tube and infusion connector and confirming adequate blood return,pulsatile flushing with normal saline was performed followed bypositive-pressure locking. The catheter advancement unit and peelable sheath were removed, fixation wings secured, and the dressing applied identically to the control group.

 

1.2.2 Catheter Maintenance and Quality Control

(1)Operators: Catheter maintenance was performed by nurses certified in venous therapy.

(2)Maintenance Protocol: Identical maintenance procedures to standardPICC care were used for both groups. To prevent catheter occlusion, patients receiving continuous infusion were flushed every6 hours using10 mL normal saline with pulsatile technique. Considering that mini-midline catheters areopen-ended, prone to blood reflux, and that obese patients haveslowed venous return and hypercoagulability,positive-pressure locking with heparin saline (10 U/mL) was applied after each infusion. Daily assessment includedcatheter external length, dressing integrity, puncture site status (redness, pain, bleeding, exudation), skin condition, catheter patency, and limb motor/sensory function.

 

1.2.3 Outcome Measures

(1) Catheterization procedural variables:

• Insertion limb

• Target vessel

• Procedure duration (from patient verification and vascular assessment to completion of catheter fixation)

• Number of puncture attempts

(2) Catheter-related complications:

Assessed according to theClinical Practice Guidelines for Common Venous Catheter Complications, including:

• Phlebitis

• Infiltration/extravasation

• Catheter occlusion

• Catheter-related thrombosis

• Catheter-related bloodstream infection (CRBSI)

• Medical adhesive–related skin injury (MARSI)

Phlebitis was graded using a0–4 scale; drug infiltration and extravasation were evaluated using0–4 grading andextravasation staging system. Catheter occlusion was defined after excluding external mechanical factors (catheter kinking, suture, filter, connector issues) and based on abnormal infusion rate, pump alarms, or resistance on aspiration/flush. Thrombosis was confirmed usingcolor Doppler ultrasound,DSA,CT, orMRI. CRBSI diagnosis requiredpaired peripheral and catheter blood cultures orcatheter segment culture. MARSI was classified into seven clinical subtypes:allergic dermatitis, contact dermatitis, epidermal stripping, skin tear, tension injury, maceration, and folliculitis.

 

Additional indicators:

•Bleeding/exudation: Persistent bleeding or clear yellow serous discharge at dressing change post-catheterization^[15].

•Catheter migration: Based on distance of external catheter displacement:1 cm (mild), 2 cm (moderate), 3 cm (severe)^[16].

•Dwell time: Duration from successful insertion to removal.

(3) Economic evaluation:

Cost analysis includedcatheterization, maintenance, and removal, as well as associated consumables and clinical handling fees.

 

1.2.4 Data Collection Methods

Outcome indicators were collected by specialist nurses and primary nurses, who received standardized training prior to data collection. Baseline data were recorded by specialist nurses before catheter insertion; if multiple laboratory test results were available, the most recent result was recorded. Primary nurses assisted specialist nurses in collecting intra-procedural data and conducted daily assessments to document catheter function and the occurrence of complications.

1.2.5 Statistical Methods

Measurement data conforming to a normal distribution were expressed as mean ± standard deviation ( (\bar{x} \pm s) ) and compared between the two groups using the t-test. Skewed data were expressed as median (interquartile range) and compared using the non-parametric Mann–Whitney U test. Categorical data were presented as frequency and percentage, and comparisons were performed using the chi-square test. A value of P < 0.05 was considered statistically significant.

 

2 Results

2.1 Comparison of General Characteristics Between Two Groups

No statistically significant differences were observed between the two groups in terms of age, gender, educational level, marital status, surgical method, length of hospital stay, preoperative fasting blood glucose, BMI, activated partial thromboplastin time (APTT), and preoperative D-dimer levels (P > 0.05), indicating comparability (see Table 1).

2.2 Comparison of Catheterization Procedures

There were no statistically significant differences between the two groups regarding the selected vessel, catheterized limb, number of puncture attempts, and procedure duration (P > 0.05) (see Table 2).

2.3 Comparison of Post-Catheterization Complication Rates, Dwell Time, and Economic Costs

There were no statistically significant differences between the two groups in the incidence of phlebitis, infiltration/extravasation, oozing/leakage, catheter occlusion, catheter-related thrombosis, MARSI, and CRBSI (P > 0.05). Catheter dwell time also showed no statistically significant difference (P > 0.05). The catheter dislodgement rate was higher in the control group than in the intervention group (P < 0.05). The economic cost was significantly higher in the control group compared with the intervention group (P < 0.05) (see Table 3).

 

Table 1. Comparison of General Baseline Characteristics Between the Two Groups

Variable	Control Group (n = 55)	Intervention Group (n = 48)	Z/χ²/t Value	P Value
Age (x̄ ± s), years	32.78 ± 6.09	33.19 ± 8.02	t = –0.291	0.772
Sex, n			χ² = 2.589	0.108
Male	18	9
Female	37	39
Educational level, n			χ² = 0.474	0.789
Secondary school or below	12	13
Junior college or high school	26	20
Bachelor’s degree or above	17	15
Marital status, n			χ² = 1.757	0.185
Married	40	29
Unmarried	15	19
Surgical procedure, n			χ² = 0.094	0.759
Sleeve gastrectomy	52	46
Sleeve gastrectomy + intestinal bypass	3	2025-11-21 From Clinical Evidence to Patient Outcomes: Why Arterial Catheters Outperform Conventional Arterial Cannulas None