Impact of Gut Microbiota and Tryptophan Metabolites on Acute Pain in Lumbar Disc Herniation Surgery Patients

2 mL of blood was used from the blood samples taken during routine surgery preparation for the patients and from the routine blood samples taken in the postoperative period, and no additional invasive intervention was performed. The investigator elucidated the relationship between picolinic acid and its variations due to microbiota alterations with VAS in acute pain. Preoperative, postoperative, 8th-hour, and 24th-hour blood samples were routinely collected from patients, with 2 mL of sample material used each time. After the necessary centrifugation processes, the relevant laboratory team analyzed the picolinic acid levels (ng/mL).

2 mL of blood was used from the blood samples taken during routine surgery preparation for the patients and from the routine blood samples taken in the postoperative period, and no additional invasive intervention was performed. The investigator elucidated the relationship between 3-Hydroxykynurenine and its variations due to microbiota alterations with VAS in acute pain. Preoperative, postoperative 8th-hour, and 24th-hour blood samples were routinely collected from patients, with 2 mL of sample material used each time. After the necessary centrifugation processes, the relevant laboratory team analyzed the 3-Hydroxykynurenine levels(ng/mL).

2 mL of blood was used from the blood samples taken during routine surgery preparation for the patients and from the routine blood samples taken in the postoperative period, and no additional invasive intervention was performed. The investigator elucidated the relationship between anthranilic acid and its variations due to microbiota alterations with VAS in acute pain. Preoperative, postoperative, 8th-hour, and 24th-hour blood samples were routinely collected from patients, with 2 mL of sample material used each time. The relevant laboratory team measured the anthranilic acid levels (ng/mL) following the required centrifugation procedures.

2 mL of blood was used from the blood samples taken during routine surgery preparation for the patients and from the routine blood samples taken in the postoperative period, and no additional invasive intervention was performed. The investigator elucidated the relationship between kynurenine and its variations due to microbiota alterations with VAS in acute pain. Preoperative, postoperative, 8th-hour, and 24th-hour blood samples were routinely collected from patients, with 2 mL of sample material used each time. After the necessary centrifugation processes, the relevant laboratory team analyzed the kynurenine levels (ng/mL).

2 mL of blood was used from the blood samples taken during routine surgery preparation for the patients and from the routine blood samples taken in the postoperative period, and no additional invasive intervention was performed. The investigator elucidated the relationship between quinolinic acid and its variations due to microbiota alterations with VAS in acute pain. Preoperative, postoperative, 8th-hour, and 24th-hour blood samples were routinely collected from patients, with 2 mL of sample material used each time. After the necessary centrifugation processes, the relevant laboratory team analyzed the quinolinic acid levels (ng/mL).

2 mL of blood was used from the blood samples taken during routine surgery preparation for the patients and from the routine blood samples taken in the postoperative period, and no additional invasive intervention was performed. The investigator elucidated the relationship between kynurenic acid and its variations due to microbiota alterations with VAS in acute pain. Preoperative, postoperative, 8th-hour, and 24th-hour blood samples were routinely collected from patients, with 2 mL of sample material used each time. After the necessary centrifugation processes, the relevant laboratory team analyzed the kynurenic acid levels (ng/mL).

2 mL of blood was used from the blood samples taken during routine surgery preparation for the patients and from the routine blood samples taken in the postoperative period, and no additional invasive intervention was performed. The investigator elucidated the relationship between xanthurenic acid and its variations due to microbiota alterations with VAS in acute pain. Preoperative, postoperative, 8th-hour, and 24th-hour blood samples were routinely collected from patients, with 2 mL of sample material used each time. After the necessary centrifugation processes, the relevant laboratory team analyzed the xanthurenic acid levels (ng/mL).

In VAS assessment, patients are typically asked to choose a value between "0, no pain" and "10, the worst imaginable pain." VAS is an 11-point scale (ranging from 0 to 10) that allows patients to numerically express the intensity of their pain. Blood samples were planned and collected from patients during the preoperative evaluation, at the 8th postoperative hour, and at the 24th postoperative hour, adhering to clinical routines for these procedures. Concurrently with each blood draw, the patient's VAS score, the nature of the pain, and vital signs were recorded.

The study measured the systolic blood pressure (mmHg) of patients at specified time points.The patients' systolic blood pressure data were recorded simultaneously with the blood samples taken during routine surgery preparation and at the 8th and 24th hours postoperatively.

The study measured the diastolic blood pressure (mmHg) of patients at specified time points.The patients' diastolic blood pressure data were recorded simultaneously with the blood samples taken during routine surgery preparation and at the 8th and 24th hours postoperatively.

The study measured patients' pulse rate (beats per minute) at specified time points.The patients' pulse data were recorded simultaneously with the blood samples taken during routine surgery preparation and at the 8th and 24th hours postoperatively.

The study measured the respiratory rate (breaths per minute) of patients at specified time points.

The patients' respiratory rate data were recorded simultaneously with the blood samples taken during routine surgery preparation and at the 8th and 24th hours postoperatively.

The study measured patients' oxygen saturation (%) at specified time points.The patients' oxygen saturation data were recorded simultaneously with the blood samples taken during routine surgery preparation and at the 8th and 24th hours postoperatively.

The McGill Pain Questionnaire (MPQ) was used to evaluate and categorize the nature of pain. The study assessed the nature and quality of acute postoperative pain using the McGill Pain Questionnaire (MPQ) at specified time points. Although all of the patients' pain was acute postoperative pain, the pain qualities were recorded simultaneously, taking into account the differences in pain qualities. The MPQ was used to evaluate and categorize the nature of pain. The MPQ includes descriptors of pain which are categorized into sensory, affective, evaluative, and miscellaneous dimensions. Each descriptor is rated on an intensity scale of 0 (none) to 3 (severe), and scores are summed to provide an overall pain score. Higher scores indicate worse pain.

The study recorded patients' comorbidities, specifically those identified during the preoperative anamnesis process, and evaluated their potential impact on the nature of pain and tryptophan metabolites. Comorbidities identified as exclusion criteria, particularly those believed to affect intestinal microbiota and related to abdominal conditions, were also considered. Patients' comorbidities identified during the preoperative anamnesis process were meticulously documented to assess their influence on pain characteristics and tryptophan metabolites. Additionally, comorbidities identified as exclusion criteria due to their potential to alter intestinal microbiota and their association with abdominal conditions were thoroughly evaluated.

Although standardization of drugs used in anesthesia is difficult, standardization of induction drugs was partially achieved because the investigators chose a single surgery group. The investigators recorded all of this data during anesthesia applications.

Our study detailedly recorded the duration of anesthesia and surgery. To ensure a certain level of standardization, we included only lumbar disc surgery, which is considered sterile. Additionally, surgeries shorter than a specified duration were excluded as they might not provide significant metabolic changes. These durations were carefully recorded throughout the entire surgery and anesthesia period. The investigators accepted these durations as one of the elimination criteria due to their potential impact on pain and physiological mechanisms.

The investigator's age was recorded during the preoperative anamnesis process to understand its influence on the study variables.

The weight of the investigator was recorded during the preoperative anesthesia process to understand its influence on the study variables.

The height of the investigator was recorded during the preoperative anamnesis process to understand its influence on the study variables.

The Body Mass Index (BMI) of the investigator was calculated from recorded height (in meters) and weight (in kilograms) during the preoperative anamnesis process to understand its influence on the study variables.BMI values are reported in units of kg/m².

The gender of the investigator was recorded during the preoperative anamnesis process to understand its influence on the study variables.