The relationship of sevoflurane consumption with metabolic age and basal metabolic rate

Background: Sevoflurane, which is one of the commonly used inhaler agents in the induction and maintenance of anesthesia, is generally administered according to the minimum alveolar concentration (MAC). The smaller the MAC, the greater the potency of the inhaler anesthetic agent. Age is an important variable for MAC, with a decrease of approximately 6% in MAC per decade. metabolic age; refers to the age calculated by the individual's body mass index, weight, body fluid and fat status. Although chronological age is one of the important risk factors for adverse clinical outcomes, two individuals of the same chronological age may have different biological aging states, resulting in different individual risk profiles. Although it is known that the effect of metabolic age and other parameters calculated by the evaluation of the body composition of the patients on awakening and recovery in inhaled agents is less than that of intravenous agents, adequate studies have not been conducted on the relationship between the patient's anesthetic gas consumption. Objective: In this study, we aimed to evaluate the relationship between metabolic age, chronological age, basal metabolic rate (BMR) and the amount of sevoflurane consumption in patients with adequate depth of anesthesia with sevoflurane, thus reducing hospital costs and preventing environmental pollution by reducing sevoflurane consumption. Materials and Methods: Body composition analysis of 79 patients, aged 18-65, ASA (American Society of Anesthesiologists physical status) I-II, who were planned for rhinoplasty or septoplasty, and who wanted to participate in the study after preoperative anesthetic evaluation, were analyzed using bioelectrical impedance analysis method. done. Patients' chronological age, height, weight, body mass index (BMI), ideal body weight, body fat ratio, body fluid ratio, body fluid mass, fat mass, lean body weight, muscle mass, BMR, metabolic age, visceral adiposity, The degree of obesity was recorded. In addition to standard monitoring, neuromonitoring with bispectral index (BIS) was performed on patients who were taken to the operating room without premedication. For the maintenance of anesthesia, sevoflurane, 50% oxygen-air mixture was initially administered at 4 lt/min until the BIS was 40-60 for the patients who were intubated after intravenous anesthesia induction, and the time to reach the target was recorded. Afterwards, the fresh gas flow was reduced to 1 lt/min and the dose of sevoflurane was adjusted so that the BIS was 40-60 throughout the case. All patients were extubated with the same protocol, and operation time, anesthesia time, extubation time, eye opening time, modified Aldrete score (MASS) 9 points, total sevoflurane consumption throughout the case, oxygen consumption and air consumption were recorded. MASS score and Ramsey score were evaluated in the recovery unit. In the study, the percent age difference formula was used to standardize the relationship between the amount of sevoflurane consumption and the chronological age and metabolic age of the patients (Percent Age Difference = (Chronological age - Metabolic age) / Chronological age). According to the percentage age difference, two different ROC analyzes were performed as positive (+) and negative (-) direction, and two different significance values were determined. On the positive side, the percentage age difference indicates patients with a chronological age greater than their metabolic age, and on the negative side, the age difference on the metabolic age indicates patients with a metabolic age above their chronological age. When we examined it positively, the cut-off value of the percent age difference was calculated as 11.7% and on the negative side as 6.6%, the patients were divided into 3 groups. Patients were named as Group A: percent age difference less than -6.6%, Group B: percent age difference between -6.6% and 11.7%, Group C: percent age difference greater than 11.7%. Results: Of the 79 patients included in the study, 29.1% were female and 70.9% male. The mean chronological age of the patients was 31.29 ± 11.9, and the mean metabolic age was 30.42 ± 12.89. The mean consumption of sevoflurane per minute was 0.19 ± 0.04 ml/min. A statistically significant difference was found between chronological age and metabolic age and total sevoflurane consumption (p=0.006; p=0.007), and a weak negative correlation was observed (r= -0.304; r= -0.301). When the patients were evaluated by dividing the percentage age difference into groups according to the cut-off value, a statistically significant difference was observed between these three groups when the groups were compared in terms of their weight, BMI, fat mass, body fluid ratio, and obesity degree (p<0.001). In the paired comparison, the difference between group A and group B and the difference between group A and group C were significant. When the groups were compared in terms of the degree of visceral adiposity of the patients, a statistically significant difference was observed between these three groups (p<0.001). In the paired comparison, the difference between group A and group B, the difference between group A and group C, and the difference between group B and group C were significant. When the groups were compared in terms of BMR, no statistically significant difference was observed between these three groups (p=0.118). When the intraoperative data were evaluated, as a result of repeated measurements of hemodynamic parameters, BIS, MAC, and endtidal carbon dioxide values at all times, when the groups were compared, no statistically significant difference was found in the measurement time periods (p>0.05). When the extubation times, eye opening times, Ramsey score and MASS values of the patients were compared, no statistically significant difference was found in all measurements (p>0.05). Conclusion: Many methods have been tried to reduce the consumption of inhalation anesthetics in order to reduce their costs and prevent environmental pollution. In our study, it was observed that the amount of sevoflurane consumed was lower when the metabolic age was greater than the chronological age in patients with adequate depth of anesthesia. We think that the use of metabolic age in inhalation anesthesia applications will reduce the consumption of sevoflurane. Keywords: Sevoflurane, Sevoflurane Consumption Amount, Metabolic Age, Chronological Age, Body Composition Analysis, Tanita, Basal Metabolic Rate