European Journal of Cardiovascular Medicine

Local anaesthetic infiltration is a cornerstone of dermatologic procedures, providing effective analgesia for a variety of minor surgical and cosmetic interventions. Although local anaesthetics are generally considered safe when administered appropriately, inadvertent intravascular injection can lead to serious complications, including local anaesthetic systemic toxicity (LAST), which may manifest as neurological or cardiovascular events if significant doses enter the circulation [1]. Conventional landmark-based techniques for local infiltration rely on anatomical knowledge and negative aspiration to minimise intravascular injection, but these methods do not allow direct visualisation of underlying vessels and may be unreliable in anatomically complex or highly vascular regions [2].

Ultrasound guidance has transformed the practice of regional anaesthesia by enabling real-time visualisation of nerves, surrounding structures, and vascular anatomy. High-frequency ultrasound allows clinicians to observe needle trajectory, target tissue planes, and the spread of local anaesthetic, thereby improving accuracy and potentially reducing complications such as vascular puncture or intravascular injection [3,4]. In large observational data from peripheral nerve blockade procedures, the use of ultrasound was associated with a lower incidence of serious complications, including LAST, compared with non-ultrasound techniques, suggesting that improved identification of vascular structures and anaesthetic spread contributes to safety [1].

While evidence supporting ultrasound guidance is robust in regional and peripheral nerve blocks, its application for superficial dermal and subcutaneous anaesthetic infiltration in dermatologic practice remains underexplored. Existing work in interventional procedures outside dermatology indicates that ultrasound-assisted local anaesthesia can reduce pain and improve procedural outcomes compared with palpation-guided techniques [5]. Furthermore, feasibility studies suggest that ultrasound-guided approaches allow precise anaesthetic delivery and may help to avoid inadvertent intravascular administration, although their clinical implementation in dermatologic settings has not been systematically evaluated [6].

Given the potential advantages of direct vessel visualisation and enhanced safety, there is a need to assess the efficacy of ultrasound guidance specifically for dermatologic local anaesthesia. This study aimed to compare the incidence of intravascular needle placement and other procedural outcomes between ultrasound-assisted and conventional landmark-based techniques in dermatologic anaesthetic infiltration.

Study design and setting: A prospective, controlled observational study was conducted in a tertiary care teaching hospital. The study was designed to evaluate the role of real-time ultrasonography in reducing inadvertent intravascular injection during dermatologic local anaesthesia. The study was conducted in accordance with the principles outlined in the Declaration of Helsinki. Written informed consent was obtained from all participants prior to enrolment.

Study population: Adult patients aged 18–65 years scheduled to undergo minor dermatologic procedures requiring local infiltration anaesthesia (e.g., excision of benign lesions, biopsies, nail procedures, and laser-assisted interventions) were considered eligible.

Inclusion criteria comprised patients with clearly identifiable procedural sites amenable to ultrasound probe placement and those willing to provide informed consent.

Exclusion criteria included known bleeding disorders, local infection at the injection site, pregnancy, prior surgery or scarring at the target area that could distort local anatomy, known hypersensitivity to local anaesthetic agents, and inability to cooperate during the procedure.

Sample size determination: Sample size was calculated based on the assumption that the use of ultrasound guidance would reduce the incidence of intravascular needle placement or vascular puncture during local anaesthetic infiltration from an expected baseline of approximately 12–15% (as suggested by procedural experience in blind injections) to below 5%. With a confidence level of 95% and a power of 80%, the minimum required sample size was estimated to be 94 participants. To account for possible exclusions and incomplete data, a total of 110 patients were recruited.

Group allocation: Participants were allocated into two groups using a computer-generated random sequence:

• Group U (Ultrasound-assisted group): Local anaesthetic infiltration performed under real-time ultrasound guidance.
• Group C (Conventional technique group): Local anaesthetic infiltration performed using standard anatomical landmark-based technique without ultrasound assistance.

Anaesthetic technique: In both groups, a standard local anaesthetic solution of 2% lignocaine with adrenaline (1:200,000) was used, with the total dose adjusted according to body weight and procedural requirements, not exceeding recommended safe limits.

In Group U, a high-frequency linear ultrasound transducer (10–15 MHz) was used. The skin was prepared with antiseptic solution, and sterile ultrasound gel was applied. The probe was positioned to visualize the subcutaneous tissue, dermis, and underlying vascular structures at the planned injection site. Color Doppler imaging was employed to identify arteries and veins prior to needle insertion. A 26–30 gauge needle was introduced using an in-plane approach, allowing continuous visualization of the needle tip. Local anaesthetic was injected only after confirming extravascular needle placement, with dynamic observation of tissue plane expansion.

In Group C, local anaesthetic infiltration was performed using conventional technique based on surface anatomy, with negative aspiration performed prior to injection as per routine clinical practice.

Outcome measures: The primary outcome was the incidence of intravascular needle placement or vascular puncture, defined by any of the following: positive aspiration of blood, ultrasound-documented entry of the needle into a vascular lumen (Group U), or immediate signs suggestive of intravascular injection.

Secondary outcomes included procedure-related pain assessed using a 10-point visual analogue scale (VAS), adequacy of anaesthesia, requirement for reinjection, procedure duration, and occurrence of local or systemic adverse events.

Data collection: Demographic details, procedural characteristics, injection site, volume of anaesthetic used, and outcome variables were recorded using a standardized data collection form. In the ultrasound group, images documenting vascular mapping and needle position were archived for verification.

Statistical analysis: Data were entered into a secure database and analyzed using standard statistical software. Continuous variables were expressed as mean ± standard deviation, while categorical variables were presented as frequencies and percentages. Intergroup comparisons were performed using the independent t-test for continuous variables and the chi-square or Fisher’s exact test for categorical variables, as appropriate. A p-value <0.05 was considered statistically significant.

Baseline demographic and procedural characteristics were comparable between the two groups (Table 1). No statistically significant differences were observed with respect to age, sex distribution, body mass index, type of dermatologic procedure performed, anatomical site of injection, or the volume of local anaesthetic administered (p > 0.05 for all variables), indicating adequate baseline homogeneity.

The primary outcome analysis demonstrated a significantly lower incidence of intravascular needle placement in Group U compared with Group C (1.8% vs 14.5%; p = 0.03) (Table 2). Positive aspiration of blood was not observed in the ultrasound-assisted group, whereas it occurred in 12.7% of patients in the conventional group, a difference that was statistically significant (p = 0.01). In the ultrasound-assisted group, pre-injection vascular mapping resulted in alteration of the planned needle trajectory to avoid visible vascular structures in 21.8% of cases. Clinical manifestations suggestive of inadvertent intravascular injection were not observed in Group U, while such signs were noted in a small proportion of patients in Group C (5.5%); however, this difference did not reach statistical significance (p = 0.08) (Table 2).

Analysis of secondary outcomes revealed that patients in the ultrasound-assisted group reported significantly lower pain scores during injection compared with those in the conventional technique group (mean VAS score 2.1 ± 0.9 vs 3.4 ± 1.2; p < 0.001) (Table 3). Adequate anaesthesia with a single injection was achieved more frequently in Group U than in Group C (92.7% vs 78.2%; p = 0.04), and the requirement for reinjection was correspondingly lower in the ultrasound-assisted group (7.3% vs 21.8%; p = 0.03) (Table 3). The mean procedure duration was slightly longer in Group U compared with Group C, though the difference was not statistically significant (6.8 ± 1.5 minutes vs 6.1 ± 1.3 minutes; p = 0.07) (Table 3). Minor local adverse events were less frequent in the ultrasound-assisted group; however, this difference did not reach statistical significance, and no systemic adverse events were observed in either group (Table 3).

When procedures were analyzed according to anatomical site, intravascular events were most commonly associated with injections in the facial region, followed by the scalp, with fewer events observed in upper and lower limb procedures (Table 4). No site-specific complications were identified in the ultrasound-assisted group.

Table 1. Baseline demographic and procedural characteristics of study participants

Table 2. Incidence of intravascular needle placement and related events

Table 3. Secondary procedural and patient-related outcomes

*Minor adverse events included transient localized swelling or ecchymosis; no systemic toxicity was observed in either group.

Table 4. Distribution of intravascular events by anatomical site (combined analysis)

In this study, ultrasound-assisted local anaesthetic infiltration in dermatologic procedures was associated with a markedly lower incidence of inadvertent intravascular needle placement compared with conventional landmark-based techniques. This finding directly reflects the advantage of real-time sonographic visualisation of vascular anatomy, which enables the clinician to adjust needle trajectory and avoid intravascular structures before injecting anaesthetic [7].

The improved procedural outcomes observed with ultrasound guidance in this study are consistent with broader evidence showing that ultrasound-assisted injections achieve higher accuracy and better outcomes than landmark-guided techniques. A meta-analysis of randomized trials on ultrasound-guided intra-articular and peri-articular injections demonstrated significantly higher accuracy of needle placement and reduced procedural pain scores compared with landmark-guided injections [8,9]. These benefits are attributed to the ability of ultrasound to visualise soft tissue structures and guide needle placement precisely, thereby reducing missed targets and unnecessary needle redirections.

Moreover, systematic reviews comparing ultrasound-guided versus landmark-guided injections across various musculoskeletal conditions have reported similar trends, with ultrasound guidance enhancing injection accuracy and improving short-term pain outcomes [10,11]. Although such studies are not specific to dermatologic anaesthesia, the underlying principle of improved needle placement reliability and pain reduction is directly relevant to superficial injection techniques.

Several clinical reports and guidelines in regional anaesthesia support the notion that ultrasound guidance reduces complications related to inadvertent vascular puncture and local anaesthetic systemic toxicity (LAST). The Anesthesia Patient Safety Foundation notes that ultrasound guidance can significantly lower the risk of vascular injury and subsequent systemic absorption by visualising and avoiding vascular structures during peripheral nerve blocks [12,13]. While peripheral blocks involve deeper anatomy than superficial dermatologic infiltration, this principle reinforces the value of image guidance in minimising intravascular entry across injection procedures.

Despite these advantages, successful implementation of ultrasound guidance depends on operator proficiency. The precision afforded by ultrasound may be compromised if the needle tip is not consistently visualised or if small vessels are overlooked due to suboptimal imaging quality or technique. Training and experience are therefore essential to realise the full safety and efficacy benefits of ultrasound guidance in clinical practice.

The findings of the present study demonstrate that the use of real-time ultrasound guidance during dermatologic local anaesthesia significantly reduces the risk of inadvertent intravascular needle placement compared with conventional landmark-based techniques. Ultrasound-assisted infiltration allowed direct visualization of subcutaneous vascular structures and facilitated modification of needle trajectory, thereby enhancing procedural safety. These results suggest that incorporating ultrasound guidance into routine dermatologic anaesthetic practice, particularly for procedures involving anatomically vascular regions, may improve patient comfort and reduce preventable complications. Larger, multicentric studies are warranted to further validate these findings and to assess the cost-effectiveness and learning curve associated with widespread implementation of ultrasound-assisted dermatologic anaesthesia.

1. Barrington MJ, Kluger R. Ultrasound guidance reduces the risk of local anesthetic systemic toxicity following peripheral nerve blockade. Reg Anesth Pain Med. 2013 Jul-Aug;38(4):289-99. doi: 10.1097/AAP.0b013e318292669b.
2. Jain PN, Ranganathan P. Ultrasound in anaesthesia. Indian J Anaesth. 2007;51(3):176-183.
3. Mahmood SMJ, Bhana NB, Kong C, Theyyunni N, Schaeffer WJ, Kropf CW, et al. Ultrasound-guided regional anesthesia (UGRA) in the emergency department: a scoping review. Pain Manag. 2024 Oct-Nov;14(10-11):571-578. doi: 10.1080/17581869.2024.2431474.
4. Marhofer P, Greher M, Kapral S. Ultrasound guidance in regional anaesthesia. Br J Anaesth. 2005 Jan;94(1):7-17. doi: 10.1093/bja/aei002.
5. Spiliopoulos S, Katsanos K, Diamantopoulos A, Karnabatidis D, Siablis D. Does ultrasound-guided lidocaine injection improve local anaesthesia before femoral artery catheterization? Clin Radiol. 2011 May;66(5):449-55. doi: 10.1016/j.crad.2011.01.002.
6. Murray TE, O'Neill DC, Lee MJ. Combining Ultrasound-Guided Vascular Access With Ultrasound-Guided Analgesia for Single Skin and Vessel Puncture. J Endovasc Ther. 2018 Jun;25(3):355-357. doi: 10.1177/1526602818761380.
7. Vegas A, Wells B, Braum P, Denault A, Miller Hance WC, Kaufman C, et al. Guidelines for Performing Ultrasound-Guided Vascular Cannulation: Recommendations of the American Society of Echocardiography. J Am Soc Echocardiogr. 2025 Feb;38(2):57-91. doi: 10.1016/j.echo.2024.12.004.
8. Huang Z, Du S, Qi Y, Chen G, Yan W. Effectiveness of Ultrasound Guidance on Intraarticular and Periarticular Joint Injections: Systematic Review and Meta-analysis of Randomized Trials. Am J Phys Med Rehabil. 2015 Oct;94(10):775-83. doi: 10.1097/PHM.0000000000000260.
9. Soh E, Li W, Ong KO, Chen W, Bautista D. Image-guided versus blind corticosteroid injections in adults with shoulder pain: a systematic review. BMC Musculoskelet Disord. 2011 Jun 25;12:137. doi: 10.1186/1471-2474-12-137.
10. Shen PC, Lin TY, Wu WT, Özçakar L, Chang KV. Comparison of ultrasound- vs. landmark-guided injections for musculoskeletal pain: an umbrella review. J Rehabil Med. 2024 Aug 26;56:jrm40679. doi: 10.2340/jrm.v56.40769.
11. Deng X, Zhu S, Li D, Luo Y, Zhang X, Tan Y, et al. Effectiveness of Ultrasound-Guided Versus Anatomic Landmark-Guided Corticosteroid Injection on Pain, Physical Function, and Safety in Patients With Subacromial Impingement Syndrome: A Systematic Review and Meta-analysis. Am J Phys Med Rehabil. 2022 Dec 1;101(12):1087-1098. doi: 10.1097/PHM.0000000000001940.
12. Ratto C, Szokol J, Lee P. Safety considerations in peripheral nerve blocks. Anesthesia Patient Safety Foundation [Internet]. Available from: https://www.apsf.org/article/safety-considerations-in-peripheral-nerve-blocks/ [cited 2025 Dec 29].
13. Barrington MJ, Kluger R. Ultrasound guidance reduces the risk of local anesthetic systemic toxicity following peripheral nerve blockade. Reg Anesth Pain Med. 2013 Jul-Aug;38(4):289-99. doi: 10.1097/AAP.0b013e318292669b.