Effects of Topical Lidocaine and Benzocaine on Pain Level and Injection Satisfaction

All individuals included in the study were provided with private health insurance to cover any potential adverse events resulting from the procedure. The participants were informed about the study both verbally and in writing, and written informed consent forms were obtained from them. Individuals who met the inclusion criteria and signed the informed consent form were assigned to study groups according to a computer-generated randomization list based on their file numbers. Accordingly, the first group was designated as the Lidocaine Spray group (Experiment I), the second group as the Benzocaine Spray group (Experiment II), and the third group as the placebo group. The design of the study, including the formation of the groups and the implementation process, is presented in Figure 3.

Two nurses working in the hemodialysis unit volunteered to participate in the study and received training from the researcher regarding the study procedures. To eliminate individual differences, one nurse performed the Arteriovenous Fistula (AVF) catheterization, while the other collected the data. These nurses were blinded to the group assignments of the patients they intervened with. In addition, the participants themselves were unaware of the groups to which they were assigned according to computer randomization. The individuals were informed about the Visual Analog Scale and the Injection Satisfaction Evaluation Scale. The nurse responsible for data collection measured and recorded in the Case Report Form the blood pressure, pulse rate, and peripheral oxygen saturation (using a fingertip pulse oximeter) five minutes before and immediately after the procedure. Blood pressure measurements were taken from the arm opposite to the Arteriovenous Fistula (AVF) catheterization site using a calibrated digital sphygmomanometer.

Since the Lidocaine Spray and Benzocaine Spray used in the groups had similar-looking bottles, the medications were used in their original containers. For the placebo group, a Lidocaine Spray bottle was emptied, washed, and sterilized in an autoclave. The sterilized glass bottle was then filled with 70% alcohol routinely used in the hospital. Subsequently, the bottles were labeled by the researchers with color-coded bands on their bases: red for the Lidocaine Spray, blue for the Benzocaine Spray, and black for the alcohol (Figure 2). The content of each bottle was identified only by the color band on its base, known exclusively to the researchers.

To prevent errors due to catheter differences, all patients included in the study received AVF catheters. To enhance the reliability of the study and avoid variations in pain levels, the same arterial and venous catheters were used for all AVF procedures. Immediately after AVF catheterization, the patient's blood pressure, pulse rate, and peripheral oxygen saturation were measured using a fingertip pulse oximeter, and the pain intensity experienced during the procedure was recorded by the nurse on the Questionnaire Form using the Visual Analog Scale (VAS) and Injection Satisfaction Evaluation Scale (ISES) values.

Inclusion criteria

• Patients aged ≥18 years,
• non-pregnant, not planning pregnancy,
• receiving hemodialysis three times weekly for at least three months,
• continuously treated at the same institution without any change in treatment regimen,
• without pain in any part of the body affecting study outcomes,
• with a Visual Analog Scale (VAS) pain score of zero at baseline,
• no analgesics within 24 hours prior,
• a baseline Algometer pressure pain threshold of 8-16 lbs.
• participants were required to understand Turkish,
• communicate effectively,
• volunteer for the study, and
• provide written informed consent.

Exclusion criteria

• Individuals with neurological disorders such as epilepsy, Alzheimer's disease, Parkinson's disease, or multiple sclerosis,
• unable or unwilling to comply with study protocol.