Pei Zou ,Kili Zhng ,Yuping Zhou ,Yu Shi ,Gungpeng Liu,*

a Department of Plastic and Reconstructive Surgery,Shanghai Tenth People’s Hospital,Tongji University School of Medicine,Shanghai 200072,China

b Department of Anesthesiology,Shanghai Skin Disease Hospital,Tongji University School of Medicine,Shanghai 200443,China

c Department of Medical Cosmetology,Shanghai Skin Disease Hospital,Tongji University School of Medicine,Shanghai 200443,China

Keywords:Upper blepharoplasty Anesthetic pain Hematoma Thick needle Thin needle

ABSTRACT Background: Upper blepharoplasty is one of the most commonly performed esthetic surgeries,but injection pain during local anesthesia often disturbs patients.The objective of this study was to identify the pain levels associated with anesthetizing the upper eyelids in blepharoplasty and determine whether injection with thin needles is associated with less pain and bleeding than injection with thick needles.Methods: The study included 50 patients who underwent bilateral upper blepharoplasty.The eyelids were anesthetized using 2% lidocaine with 1:100 000 epinephrine.One upper eyelid was randomly injected with a thin needle(26G)and the other with a thick needle(22G).The pain level was scored by patients immediately after the injection of each eyelid using a visual analog scale(VAS)ranging from 0 to 10.The incidence of eyelid hematomas caused by the anesthetic injection was also recorded.Results: The VAS scores in eyelids injected with thin needles were not significantly lower than those in eyelids injected with thick needles(4.0 vs.4.0,P=0.393).The formation of eyelid bruises caused by thin-needle injection was less frequent than that caused by thick-needle injection(16%vs.26%),but there was no significant difference between the two groups (P=0.326).Conclusion: Using thin needles for local anesthesia during upper blepharoplasty could not significantly decrease injection pain or hematoma occurrence compared with that associated with using thick needles.

1.Introduction

Upper blepharoplasty is one of the most commonly performed facial esthetic procedures.1To achieve satisfactory results,effective prevention and management of the surgical complications,such as pain and bleeding,are also of great concerns to patients.

Eyelid surgeries are routinely performed under local anesthesia to save operation time and prevent systemic anesthesia-related risks.2However,injection pain during local anesthesia is a major cause of anxiety,discomfort,and psychological distress.Hence,close attention has been paid to methods that can reduce anesthetic pain and improve patient experience in blepharoplasty.Yu et al.3proposed that the use of blunt needles to administer local anesthesia in upper blepharoplasty was less likely to cause pain and hemorrhage than the use of sharp needles.Other studies compared the injection pain levels with different anesthetic solutions.4,5

In clinical settings,it is commonly believed that thick needles are significantly correlated with injection pain and the occurrence of bleeding.However,to date,no studies have provided such evidence in cases of local anesthesia for upper blepharoplasty.The purpose of our current study was to identify the actual pain levels associated with anesthetizing the upper eyelids with thin and thick needles and to investigate which type of needle can minimize the likelihood of bleeding.

2.Patients and methods

This study was a randomized,double-blind,crossover clinical trial,approved by the Ethical Review Board of Shanghai Tenth People’s Hospital(No.2021-0081).From July 2021 to December 2021,50 adult patients who enrolled for bilateral upper eyelid blepharoplasty in the Department of Plastic and Reconstructive Surgery of this hospital were included in our study,and all patients provided written informed consent prior to the procedure.The exclusion criteria were as follows:(1) previous surgery on the eyelids;(2) history of taking nonsteroidal antiinflammatory drugs;(3) abnormal coagulation function;(4) hypersensitivity to lidocaine.

The upper eyelid anesthesia administration and surgeries were performed by a single plastic surgeon(Liu G).The selection of each eyelid to be injected with either needle type was determined by an assistant(Zou P) using a randomization software.In all patients,the right eyelid was first to get injected and undergo surgery.Each upper eyelid was routinely anesthetized with 5 mL of lidocaine hydrochloride (20 mg/mL) and 10 μg/mL epinephrine(1:100 000)at a similar speed(0.1 mL/s).A 5-mL sterile syringe was used to anesthetize the eyelids with a thin needle(26G;16 mm in length,regular bevel)or a thick needle(22G;32 mm in length,regular bevel) (Fig.1).Only one injection was administered on the thick-needle side,but two injections were needed on the other side due to the shorter length of the thin needle.

Patients were required to score their pain using a visual analog scale(VAS) ranging from 0 (no pain at all) to 10 (unbearable pain) immediately after anesthetic injection,without knowing the needle type used on each side.They were also asked if the pain level was equal on both sides,or if the pain was more in the first (right) or the second (left) upper eyelid.Photographs of the eyelids of each patient were taken after surgical incision to record the incidence of hematomas caused by anesthetic injection.

The results of this study are expressed as frequencies in percentages for categorical variables,as median ranges for non-normally distributed continuous variables,and as means (standard deviations) for normally distributed continuous variables.Data on pain scores with thick and thin needles were assessed using the Wilcoxon signed-rank test,and differences in the occurrence of hematomas were analyzed using the chisquared test.Statistical analyses were performed using SPSS (version 20.0;SPSS Inc.,Chicago,IL,USA),with the significance level defined as P＜0.05.

Fig.1.(A) Commonly available syringes and corresponding needles used for local anesthetic injection.(B)The thin needle(26G)and thick needle(22G)used in this study.

3.Results

A total of 50 patients(2 men and 48 women)who underwent bilateral upper eyelid surgeries were included in this study,with ages ranging from 18 to 73 years (average age,46.6 years).In 23 patients,the first(right) upper eyelid was anesthetized with thin needles (26G) and the second (left) upper eyelid was injected with thick needles (22G);in the other 27 patients,the sequence was contrariwise.

The median pain score was 4.0(range 1-8)in the thin-needle group and 4.0 (range 2-8) in the thick-needle group.Thirteen patients (26%)indicated that eyelid anesthesia with thin needles was less painful,and 11 patients(22%)rated lower pain levels for thick needles.The majority(26 cases,52%)reported no difference between the two sides.The pain difference in the VAS scores of the two groups (thick minus thin) was mostly zero,indicating that it was equally painful when anesthetizing the eyelids with thick or thin needles(P=0.393,Fig.2A).

The median pain score was 4.0(range 1-8)in the eyelids injected first(right eyelid)and 4.5(range 2-7)in those injected second(left eyelid).In 14 patients(28%),the pain was more severe in the eyelid injected second than in the eyelid injected first.Ten patients (20%) reported opposite results,and in the other 26 cases (52%),the VAS scores were equal.Therefore,the injection sequence did not affect anesthetic pain(P=0.691,Fig.2B).

If the subcutaneous blood vessels were ruptured during local anesthesia,eyelid bruises,caused by blood accumulation,could be clearly visible and recorded by photographs after skin incision (Fig.3).The incidence of eyelid bruises caused by the thin-needle injection (8/50,16%) was lower than that caused by the thick-needle injection (13/50,26%),but there was no significant difference between the two groups(P=0.326).Injections that caused hematomas (both needle sizes were pooled together) were related to significantly higher pain scores than those without bleeding(5.0 vs.4.0,P=0.009).

4.Discussion

Local anesthetic infiltration in the eyelids is painful and often invokes fear among patients.Effective pain control during blepharoplasty is crucial in making patients feel comfortable and reducing their anxiety.3Factors that can influence cutaneous injection pain include the needle diameter,needle sharpness or bluntness,insertion depth,and volume and composition of the injected substance.Therefore,various attempts have been made to alleviate injection pain,such as changing the type of anesthetic solution,buffering the solution pH,slowing the injection rate,and other techniques.6

The needle diameter can significantly affect the pain level during needle insertion into human skin,and reducing the needle gauge can decrease pain and increase patient acceptance.7However,smaller needles(29G-31G)used for vaccine and insulin delivery may not be suitable for anesthetizing the eyelids in terms of the injection rate,volume,and depth.In the present study,the features of using thick (22G,32 mm in length) and thin (26G,16 mm in length) needles,which are most frequently used for subcutaneous injection during blepharoplasty(Fig.1),were investigated and compared.Our results showed no significant difference in pain scores between the two groups(both=4.0).In another study,the mean VAS scores using sharp and blunt needles(both of 27G and 50 mm in length) for anesthetic injection in upper eyelid surgeries were reported to be 5.48 and 4.64,respectively,3confirming that the needle size was not critical in decreasing injection pain during blepharoplasty.

Fig.2.(A)The difference in pain scores induced by the thin and thick needles(thick minus thin)revealed that the degree of pain in both groups was similar.(B)The difference in pain scores of the first and second eyelids (second minus first) indicated that the pain level in both sides was similar.

Fig.3.Eyelid hematoma caused by anesthetic injection with a thick needle(22G,in a 52-year-old female)and a thin needle(26G,in a 73-year-old female).Patients provided written informed consents to publish their photographs.

The standard solution for local anesthesia is 2% lidocaine with 1:100 000 epinephrine,which can induce rapid surgical anesthesia and provide adequate duration for the surgery.8In this study,5 mL of lidocaine with epinephrine was injected in each eyelid,and no further anesthetic infiltration was added due to sufficient pain relief.In addition to the needle size,we also found no significant differences in pain scores between bilateral eyelids.

Generally,there is a positive correlation between the needle size and the frequency of bleeding at the injection site.9The thinner a needle is,the less tissue damage it will cause.In this study,the incidence of hematomas was 16% (26G) vs.26% (22G),which was lower in the thin needle group,but the difference was not statistically significant(P=0.326).This inconsistency was probably attributable to the relatively small sample size (n=50),and a larger sample size may have yielded different results.On the other hand,injections that caused bruises(when both 22G and 26G were pooled together) were associated with significantly higher pain scores than those that did not(P=0.009).

One limitation of this study was the age and sex bias due to our relatively small sample size(age range of 18-73 years with 96%women).Female patients tend to report higher pain scores than male patients,and older persons may have lower pain perception than younger or middleaged patients.10,11Second,our results showed that using both thin and thick needles had similar chances of penetrating blood vessels when performing local anesthesia for upper blepharoplasty,but we did not accurately evaluate the areas of hematomas.The degree and severity of bruises can be evaluated using suitable rating scales for further investigation.

5.Conclusion

Our present study demonstrates that the use of thin needles(26G)for local anesthesia during upper blepharoplasty does not decrease the injection pain and the incidence of hematomas compared to those with the use of thick needles(22G).

Ethics approval and consent to participant

This prospective clinical study was approved by the Ethical Review Board of Shanghai Tenth People’s Hospital(approval no.2021-0081).All participants provided written informed consent prior to study enrollment.

Consent for publication

The patients gave written informed consent to publish the data contained within this study.

Competing interests

The authors declare that they have no competing interests.

Authors’ contributions

Zou P:Writing-Original Draft,Conceptualization,Methodology.Zhang K:Data Curation,Visualization,Investigation.Zhou Y:Software,Validation.Shi Y:Supervision.Liu G:Writing-Review and Editing,Supervision,Project administration.

Acknowledgments

The study was sponsored by the National Natural Science Foundation of China(grant no.31870974).