The Effect of Buffered Lidocaine Versus Nonbuffered Lidocaine on Pain Scores During Infiltration for Vulvar Biopsies

BACKGROUND/INTRODUCTION:

Certain procedures, particularly those involving the skin, can cause pain and distress in
patients. Often , a local anesthetic is used to dull the sensation and improve patient
experience and satisfaction. The procedure at hand dictates the mode of delivery of the
anesthetic, but typically immediate and fast acting analgesia requires infiltration.
Lidocaine is in the amide class of local anesthetics and is the most commonly used agent for
infiltration. Lidocaine is usually given as a 1 percent solution and can be combined with
epinephrine in order to prolong the duration of action, decrease local bleeding via local
vasoconstriction and decrease systemic absorption of the lidocaine.

It is well known that lidocaine injection can be painful, likely secondary to the acidity. A
meta analysis published in the Cochrane Database of 23 trials that compared pain during
infiltration of buffered or non-buffered lidocaine found that patients receiving buffered
lidocaine reported significantly less pain than those who received non-buffered lidocaine.
The decrease in pain was greater for patients who received lidocaine with epinephrine but was
also present for those who received lidocaine without epinephrine. The authors' conclusion
was that "increasing the pH of lidocaine decreased pain on injection and augmented patient
comfort and satisfaction". The studies included in this review however were mainly focused on
lacerations, carpal tunnel decompression and "outpatient procedures". There were two studies
that specifically involved OB/GYN patients; one investigated buffered lidocaine during
epidural catheter removal and the other investigated buffered lidocaine during Norplant
insertion. Since the Cochrane Review was published, one further gynecologic study
investigating buffered lidocaine has been published involving cervical loop excision.

To date, there are no studies investigating the efficacy of buffered lidocaine during
procedures on the vulva. The vulva is a particularly sensitive region to have a biopsy
performed because it has extensive innervation, a large blood supply and it involves a pelvic
exam which can be associated with increased anxiety. As many OBGYNs know, the vulva can be
affected by a variety of conditions both benign and malignant. A crucial aspect of caring for
women with vulvar complaints is conducting biopsies of lesions to ensure no occult malignancy
and/or to further classify a diagnosis with histology. Use of local anesthetic is standard of
care during biopsy but can add to the pain and discomfort of an already painful procedure.
Some sources recommend use of topical anesthetic prior to infiltration of lidocaine,
particularly in the pediatric patient. However, this technique requires the topical
anesthetic be applied 20-60 minutes prior to the biopsy, which may not be feasible in a busy
outpatient practice. Currently, the American Board of Obstetrics and Gynecology suggests 8.4%
sodium bicarbonate can be added to lidocaine to minimize discomfort. However, there is
currently no standard anesthesia recommendations and this is often not being done in clinical
practice.

Given the obstacles to topical anesthetic usage, the fact that it does not address the pain
involved with lidocaine infiltration and the lack of published literature on use of buffered
lidocaine on the vulva, this study aims to investigate the use of buffered lidocaine versus
non-buffered lidocaine in the setting of vulvar biopsy using a visual analog scale.

Research Question: Does buffered lidocaine decrease pain scores on a visual analogue scale
during infiltration for local anesthesia during vulvar biopsy?

METHODOLOGY/ STUDY DESIGN:

This study will be a double blinded, randomized controlled trial to be performed at the
Women's Primary Care Center and The Program In Women's Oncology Clinics. Patients will be
recruited as outlined below and assigned a sequential study identification number. They will
be asked to complete the questions on the Data Collection Form/Survey (see form titled "Data
Collection Form") and if they agree to the study, will sign the Informed Consent (see form
titled "Informed Consent"). The Data Collection Form/Survey will be given to the patient upon
decision to perform a vulvar biopsy by the provider. The patient will be consented by
approved research personnel. Then, the patient will undergo a vulvar biopsy as per clinician
protocol. Baseline pain scores will be collected using the visual analogue scale. After skin
prep, the pre-filled, sequentially numbered, randomized 25 gauge syringes will be used to
inject 3ml of either buffered or non-buffered lidocaine prepared by the pharmacy as outlined
below. The biopsy will then proceed as per clinical standard. The patient will be presented a
100 mm visual analogue scale to mark their pain level. A total of three pain scores will be
obtained as the patient marks on the pain scale when instructed: A baseline pain score prior
to intervention, pain score at time of infiltration, and pain score at the completion of the
biopsy. The Data Collection Form/Survey will be collected from the patient by approved
research personnel and placed in secure storage. Data will be entered into a secure
electronic database for statistical analysis. Nursing staff at the WPCC may be present for
the biopsy, but will not be involved in the conduction of the study.

The study population of interest is patients undergoing vulvar biopsy for noninfectious
lesions. These clinic sites were chosen for this project given the relatively high volume of
such procedures. There are a number of other trials that have taken place or are ongoing at
the Women's Primary Care Center and The Program In Women's Oncology Office, such that ample
infrastructure and resources are available. Many of the patients have been approached for
other research trials, and may be more willing to participate for that reason.

SAMPLE SIZE: The sample size calculation is based on the null hypothesis that the mean pain
score will be the same in women treated with buffered lidocaine as in those treated with
non-buffered placebo. The alternative hypothesis (two-sided) is that the mean pain score in
women treated with buffered lidocaine will be different than those treated with non-buffered
lidocaine. Assuming an alpha of 0.05, 80% power, and a standard deviation of 21-30 mm (based
on a previous study measuring pain with tenaculum application and intracervical block), we
will need to recruit 64 women per arm to be able to detect a 15 mm mean difference between
groups on the 100 mm VAS. This difference is derived from a prior study showing the minimally
clinically significant difference in acute pain on the VAS is 12 mm, with a 95% confidence
interval range from 9 to 15 mm. Therefore, we plan to recruit a total of 128 patients, or 64
patients per arm.

CRITERIA FOR SUBJECT SELECTION/RECRUITMENT METHOD: Participants will be recruited from June
2015-April 2018. All patients at the Women's Primary Care Center and The Program In Women's
Oncology Clinic who are to undergo a vulvar biopsy for a noninfectious vulvar lesion will be
approached by the research assistant or provider in the clinic and asked to participate in
the study. The research assistant/provider will then review the study protocol, risks,
benefits, and the written informed consent form with the patient (see form titled "Informed
Consent"). If the patient wishes to participate, written informed consent for the study will
be obtained by study personnel prior to the biopsy. Women from all racial and ethnic groups
will be considered for inclusion in this study and no person shall be excluded based on their
race or ethnicity.

DATA COLLECTION/INTERPRETATION: All data will be collected prospectively by the research
staff or nursing staff (nursing staff at the WPCC will not be involved in research
activities). Before the biopsy, a questionnaire will be completed by the patient to identify
any factors that may influence pain perceived during the biopsy as well as baseline
demographic information: age, race/ethnicity, education level, any analgesics taken the day
of the biopsy. The physician performing the biopsy and indication for the biopsy will also be
noted. The primary outcome of interest will be pain score on the visual analogue scale during
lidocaine infiltration. A total of three pain scores will be obtained by the research
assistant or nurse: A baseline pain score prior to intervention, pain score at time of
infiltration, and pain score at the completion of the biopsy. This will be measured by asking
the patient to mark her pain level on a 100 mm scale at each predetermined time point.

The analysis plan is based on the primary outcome of mean pain score during lidocaine
infiltration as measured on the 0 mm to 100 mm VAS. The investigators are comparing two
groups: 1) buffered lidocaine 2) non-buffered lidocaine. If the data are normally
distributed, we will compare mean pain scores between the two groups using a t-test. If the
data deviate notably from normality, the nonparametric Wilcoxon rank sum test will be used
for comparisons. Imbalances will be handled by adjustment for covariates in multiple linear
regression. The investigators will use an intention to treat analysis.

After written informed consent is obtained and subjects are admitted into the study,
participants will be randomized to one of two groups, buffered lidocaine or non-buffered
lidocaine. Randomization lists will be computer generated with a one-to-one allocation ratio
in blocks by the WIH pharmacy staff. After signing the consent form, each participant will be
assigned a study ID number corresponding with the order of recruitment into the study. The
pharmacy will prepare identical syringes containing 9 ml of the 1% lidocaine + 1 ml of sodium
bicarbonate or 10 ml 1% lidocaine labeled only with the study name and sequentially numbered.
The numbered syringe corresponding with the participant's study ID number will be obtained by
the study staff from the locked refrigerator in the Women's Primary Care Center or The
Program In Women's Oncology. The syringes will appear identical. Participants, study
personnel, the medical assistant, and the clinician will be blinded to the assignment.

FACILITIES: All patient related aspects of the study will transpire in the Women's Primary
Care Center and The Program In Women's Oncology. Data processing and interpretation will take
place at Women and Infants Hospital in conjunction with the Division of Research.

CONFIDENTIALITY: The patients enrolled in the study will be asked permission for access to
their medical records. To ensure patient confidentiality, all forms will be marked with only
the participant ID number, with a key containing identifying information kept separately in a
locked cabinet that only research personnel will have access to. Electronic data will be
stored on the Care New England file server, a file server that is located in a physically
secured data center. Access to Care New England data center is card-controlled and all access
to the server room is recorded. Care New England computer account management policies and
practices ensure that computer access to the study database will be limited to key study
personnel.

SAFETY: Study personnel will meet to review safety issues and logistics at 25%, 50% and 75%
recruitment. Adverse events and complications will be recorded on the data collection sheet
which will be reviewed by the PI on a rolling basis.

PERSONNEL/ADMINISTRATION AND ORGANIZATIONAL STRUCTURE:

Patients will be recruited by and data collected by designated research staff and/or
providers in the Women's Primary Care Center and The Program In Women's Oncology. The
biopsies will be performed by designated key research personnel. These providers are educated
on the standard protocol utilized by the Center. Nursing staff at the WPCC may be present for
the biopsy, but will not be involved in the conduction of the study.

Inclusion Criteria:

- Patient at the Women's Primary Care Center

- Ages 18 and older

- Require a vulvar biopsy for a noninfectious vulvar lesion.

- Able to read English or Spanish

- Able to give informed consent for involvement in the study

Exclusion Criteria:

- Allergy to lidocaine

- Unable to give informed consent

- Unable to read English or Spanish