The Effect of Short-Term Transcutaneous Electrical Stimulation of Auricular Vagus Nerve on Parameters of Heart Rate Variability

Round 1

Reviewer 1 Report

The authors present an interesting dataset associating vagus nerve stimulation and heart rate variability parameters. This will provide important information for the management of different health conditions. Hereunder, I am presenting some comments aimed at improving the understanding of the article.

General comments: 

Please, add information on the specific procedures conducted: subject position for measurements, duration of the recordings, the temperature of the room, etc.

I cannot see the supplementary tables. Did the authors control for participant habits before the measurements (e.g., physical activity, nutrition, hydration, stress, cognitive fatigue)?

Please, confirm that the copyright license is described and appropriate.

Please, add potential sources of error and noise.

 

Specific comments:

Lines 42-43 add commas between the words of the list. 

Line 110, please present the meaning of the abbreviation LF/HF.

Author Response

Please, add information on the specific procedures conducted: subject position for measurements, duration of the recordings, the temperature of the room, etc.

We are grateful to the reviewer for very important comments. Indeed, adding this information is important for understanding the procedure as a whole, it will obviously improve the article.

We have added this information to the “Methods” section.

The study was conducted in the evening hours (5.00-6.00 pm) before meal, so the possible influence of daily fluctuations and postprandial influences on the autonomic regulation of the cardiovascular system were excluded and monotonous conditions for all patients were created. The registration of the studied signals took place in a specialized functional diagnostics room applicable the medical requirements for such offices (temperature 21-24°C, required humidity, lighting, wall covering, etc.), in the presence of a research doctor, without unauthorized persons. The influence of noise, various kinds of sounds, etc. were also excluded.

All patients were in a horizontal position at all points of the study. The first (initial, without stimulation) ECG recording was performed after the patient assumed a horizontal position in at least 10 minutes. At all stages of the study, the patients breathing was arbitrary.

 

I cannot see the supplementary tables. Did the authors control for participant habits before the measurements (e.g., physical activity, nutrition, hydration, stress, cognitive fatigue)?

We are grateful to the reviewer for important comments.

The supplementary materials contain all the parameters that we evaluated, including clinical anamnestic data about the presence of cardiovascular pathology, drug therapy, data from instrumental and laboratory diagnostic standardized methods that are used to diagnose cardiovascular pathology (echocardiography, coronary angiography, etc.)

The information about nutrition, hydration, stress, etc. was not included in our study, since these were cardiosurgical patients. In addition, unfortunately, I do not know any objective method of controlling cognitive fatigue and stress, validated for medical institutions.

 

Please, confirm that the copyright license is described and appropriate.

A link with a description of the license is provided in the "Open Science Framework" repository by the link (https://doi.org/10.17605/OSF.IO/STU62), where the dataset is located. A screenshot is attached. (Auricular Vagus Stimulation and Heart Rate Variability © 2023 by Vladimir Shvartz is licensed under CC BY 4.0).

 

Please, add potential sources of error and noise.

As we mentioned above, we conducted the study in a specialized functional diagnostics room applicable the medical requirements for such offices. Of course, any electronic equipment located nearby could theoretically be the source of interference and noise. However, the equipment we use is legally certified in our country as medical equipment and can be used for medical purposes. In such devices, there are all methods of suppressing the influence of noise on the parameters of the studied signal. Nevertheless, as the reviewer asks, we mention the equipment located in the room where the research was conducted.

The following equipment was also in the room: digital electrocardiograph "BTL Flexi ECG", BTL, UK), 2) Doppler echocardiographs (Sonoline Si-450, Siemens, Germany), (IE-33 Philips Medical Systems, USA).

 

Specific comments:

Lines 42-43 add commas between the words of the list. 

Line 110, please present the meaning of the abbreviation LF/HF.

We are grateful to the reviewer for these comments. We fixed them.

Author Response File: Author Response.doc

Reviewer 2 Report

Comments for author File: Comments.pdf

Author Response

We are grateful to the reviewer for the high assessment of our work.

The additional tables contain all the parameters that we evaluated, including clinical anamnestic data about the presence of cardiovascular pathology, drug therapy, data from instrumental and laboratory diagnostic standardized methods that are used to diagnose cardiovascular pathology (echocardiography, coronary angiography, etc.). Their clinical, instrumental, and laboratory characteristics are presented in Tables S1 and S2. Comparative analysis of the studied HRV parameters at baseline and at all periods of the study is presented in Tables S3-S7.