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ORIGINAL ARTICLE
Year : 2022  |  Volume : 25  |  Issue : 11  |  Page : 1911-1917

Reliability of low-flow anesthesia procedures in patients undergoing laparoscopic cholecystectomy: Their effects on our costs and ecological balance


1 Department of Anesthesiology and Reanimation Clinic, Malatya Training and Research Hospital, Malatya, Turkey
2 Department of Anesthesiology and Reanimation Clinic, Malatya Turgut Ozal University, Malatya, Turkey

Date of Submission03-Jun-2022
Date of Acceptance25-Jul-2022
Date of Web Publication18-Nov-2022

Correspondence Address:
Dr. E Koca
Department of Anesthesiology and Reanimation Clinic, Malatya Training and Research Hospital, Malatya
Turkey
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njcp.njcp_387_22

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   Abstract 


Background and Aim: The many advantages of low-flow anesthesia are now recognized. Apart from its positive effects on the patient, it is clear that it is a method that all anesthetists should prefer with its positive effects on the ecological balance. Patients and Methods: This prospective, observational, cross-sectional study included 80 patients aged 18-65 years with an American Society of Anesthesiologists score of 1-2 (ASA I-II) who were scheduled for laparoscopic cholecystectomy. Results: Although the operation time and anesthesia duration were higher in the low anesthesia group group, sevoflurane consumption was lower. Considering the operation times, up to 60% savings were achieved. Conclusion: In our study, we safely applied low-flow anesthesia to our patients with advanced monitoring. We believe that low-flow anesthesia is advantageous in terms of both patients' health, ecological balance, and cost.

Keywords: Anesthesia, cholecystectomy, costs, ecological balance, low-flow anesthesia, patient


How to cite this article:
Kutlusoy S, Koca E, Aydin A. Reliability of low-flow anesthesia procedures in patients undergoing laparoscopic cholecystectomy: Their effects on our costs and ecological balance. Niger J Clin Pract 2022;25:1911-7

How to cite this URL:
Kutlusoy S, Koca E, Aydin A. Reliability of low-flow anesthesia procedures in patients undergoing laparoscopic cholecystectomy: Their effects on our costs and ecological balance. Niger J Clin Pract [serial online] 2022 [cited 2022 Dec 2];25:1911-7. Available from: https://www.njcponline.com/text.asp?2022/25/11/1911/361467




   Introduction Top


Low-flow anesthesia is an inhalation anesthetic technique in which at least 50% of the gases are returned to the lungs after capturing carbon dioxide (CO2) from exhaled gases using high-standard rebreathing anesthesia devices.[1] Low-flow anesthesia is administered at gas flow rates of 1 lt/min or less with modern anesthesia devices that allow continuous and detailed monitoring of the anesthetic gas mixture.[2] The use of low fresh gas flow (FGF) (0.35-1 L/min) during inhalation anesthesia increases humidity levels of inhaled anesthetic gases and minimizes heat loss, which not only improves the gas dynamics for the lungs but also provides physiological benefits such as improved mucociliary function and maintenance of body temperature.[3],[4] Although low-flow anesthesia (LFA) is associated with risks such as hypoxia, hypercapnia, insufficient depth of anesthesia, and accumulation of potential toxic gases, adequate anesthesia safety has been achieved thanks to high-standard anesthesia devices, new CO2 absorbers, and advanced monitoring techniques.[5]

According to the classification of flow rates of gases into anesthetic circuits proposed by Baker and Simionescu, very high flow is defined as >4 L/min, high flow as 2-4 L/min, medium flow as 1-2 L/min, low flow as 0.5-1.0 L/min, minimal flow as 0.25-0.5 L/min, metabolic flow as <0.25 L/min (Baker and Simionescu).[6]

The use of LFA decreases the consumption of inhaler agents and provides savings of up to 75%,[3] resulting in a reduction in waste anesthetic gas and the health risks of the operating room personnel, while maintaining the balance in the ecosystems.[3] In laparoscopic abdominal surgeries, CO2 insufflation and concerns about hypoxemia and hypercapnia due to lithotomy position limited low FGF practices; however, there are many studies showing its successful use.[7],[8] This study aimed to investigate the effects of sevoflurane anesthesia with low-flow and high-flow FGF on hemodynamics, oxygenation, gas consumption, and recovery in laparoscopic cholecystectomy cases and to draw attention to the cost and ecological effects related to the reduction in sevoflurane consumption.


   Subjects and Methods Top


Following obtaining the ethical approval (No 2021/122) from Malatya Turgut Özal University Clinical Research Ethics Committee, this prospective, observational, cross-sectional study included 80 patients aged 18-65 years with an American Society of Anesthesiologists score of 1-2 (ASA I-II) who were scheduled for laparoscopic cholecystectomy. The study adhered to the ethical principles of the Declaration of Helsinki. Patients who did not want to participate in the study, emergency cases and those with ASA III or higher scores were excluded from the study. After obtaining informed consent, the patients were randomly divided into two groups. No premedication was administered. Age, gender, and ASA scores were recorded. After transferring the patients to the operating room, electrocardiography, heart rate/minute (HR/min), systolic arterial pressure (SAP-mmHg), diastolic arterial pressure (DAP-mmHg), mean arterial pressure (MAP-mmHg), peripheral oxygen saturation (SpO2%) were monitored. Total oxygen content (SpOC), perfusion index (PI), oxygen reserve index (ORI) (Root – Masimo, Irvine, CA, USA), and Bispectral Index (BIS) were used for monitoring the depth of anesthesia, and baseline values were recorded. Before the induction of anesthesia, a leak test was performed on the anesthesia device in each patient. Soda lime used as a CO2 absorber was replaced when its color changed. After preoxygenation of the patients, intravenous anesthesia was administered with lidocaine 1 mg/kg, propofol 2 mg kg, fentanyl 1 mcg/kg, rocuronium 0.6 mg/kg, and after induction, adequate anesthesia depth was achieved and patients were connected to the anesthesia device after intubation with an endotracheal tube of appropriate size. End-tidal carbon dioxide (EtCO2), sevoflurane amount, and oxygen flow were continuously monitored after intubation. A combination of 4 L min 100% oxygen (O2) and 3% sevoflurane (Sevorane®, Liquid 100%, Queenborough, UK) was administered to Group 1 (T1 group) for 10 min. The fresh gas flow was then set at 1 L/min, and 60% O2+40% air and 2-3% sevoflurane were administered. A combination of 4 L/min 100% oxygen (O2) and 3% sevoflurane (Sevorane®, Liquid 100%, Queenborough, UK) was administered to Group 2 (T2 group) for 10 min. The fresh gas flow was then set at 2.5 L/min, and 60% O2+40% air and 2-3% sevoflurane were administered. Tramadol (1 mg/kg) was administered to both groups for postoperative pain relief. We used 5 cm H2O PEEP to prevent intraoperative atelectasis and we managed to maintain the BIS value around 40-50 for the depth of anesthesia during the operation.

HR, MAP, SpO2, PI, ORi, and SPOC values of the patients were recorded throughout the surgery at baseline, after anesthesia induction, after intubation, and before and after extubation. At the end of the operation, the inhaled anesthetic agent was discontinued in all patients. Ventilation was continued manually with 100% O2. Neostigmine 0.04 mg/kg-1 (Neostigmine, Adeka Samsun, Turkey) and atropine 0.01-0.02 mg/kg (Atropine Sulfate, Galen Medikal, Istanbul, Turkey, 0.02 mg/kg) was intravenously administered for reversal of neuromuscular block and the patients were extubated. Total operative time, anesthesia time, amount of fluid administered, and amount of anesthetic gas consumed were recorded separately for each patient (through the anesthesia device). The patients were postoperatively transferred to the recovery unit. In the recovery room, HR, MAP, and SpO2 were recorded at 1, 5, and 10 min.

Statistical analysis

The analysis of the study data was carried out using the Statistical Package for the Social Sciences (SPSS) version 26 software. The Shapiro–Wilk test was used to check if the data included in the study follow a normal distribution. The level of significance for comparison tests was set at P < 0.05. Since the variables were non-normally distributed (p > 0.05), the analysis was continued with non-parametric test methods. The Mann–Whitney U test was used to compare differences between two independent groups since the assumption of normality was not met. In the analysis of categorical data, Chi-square (χ2) analysis was performed by creating crosstabs.


   Results Top


During the study, data of 80 cases, 40 cases from each group, were collected. Demographic data were similar between groups. There was no statistically significant difference between T1 and T2 flow groups according to the variables of gender, ASA, DM, HT, COPD, CAD in the participants P > 0.05 [Table 1].
Table 1: Demographic Data

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The mean age was 48.5 in the T1 group and 47 in the T2 group. There was no significant age difference between the groups P > 0.05 [Table 2]. The operation time was 67 min in the T1 group and 52 min in the T2 group, P < 0.001. Anesthesia duration was 74 min in the T1 group and 62 min in the T2 group p: 0.001. The fluid administered was 1100 ml in the T1 group and 1010 ml in the T2 group p: 0.020. There was a statistically significant difference between the two groups in terms of operation time, anesthesia duration, and fluid administered [Table 2]. Between the groups, the median value of sevoflurane consumption was 17.5 in the T1 group and 22-P < 0.001 in the T2 group, which was significantly lower. Considering the consumption cost of sevoflurane, it was 2,8 dollar in the T1 group and 3,7 dollars in the T2 group [Figure 1].
Table 2: Comparison of age, duration of anesthesia and sevoflurane consumption variables according to flows

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Figure 1: Sevoflurane consumption among groups

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Although the operation time and anesthesia duration were higher in the T1 group, sevoflurane consumption was lower. Considering the operation times, up to 60% savings were achieved [Table 2]. Between groups, baseline MAP was slightly different from 101.0 mmHg in the T1 group to 111.5 mmHg in the T2 group [Table 3]. Baseline ORI, HR, PI, and SPOC were similar in the T1 and T2 groups [Table 3]. Among the groups, MAP, HR were more stable, SpO2 and SPOC were higher in T1 group after intubation, ORI was higher in T2 group. PI values were normal in both groups [Table 4] [Figure 2]. Pre-extubation MAP, ORI, HR, PI were similar. SPOC and SpO2 were higher in the T1 group [Table 5]. Post-extubation MAP, SpO2, and PI were similar in the participants included in the study. Although HR and SPOC were high in the T1 group, no statistically significant difference was found P > 0.05 [Table 6]. When the data of the participants included in the study in the recovery room in the 1st, 5th and 10th min were compared, 1 min-HR, 5 min-SpO2, 5 min-MAP were more stable in the T1 group, 10 min-MAP, 10 min-SpO2, and 10 min-HR were more stable in the T1 group than in the T2 group P < 0.05 [Table 7].
Table 3: Comparison of baseline MAP, ORI, HR, PI and SPOC values between groups

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Table 4: Comparison of MAP, ORI, HR, PI, SpO2 and SPOC values between groups after intubation

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Table 5: Comparison of MAP, ORI, HR, PI and SPOC values between groups before extubation

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Table 6: Comparison of MAP, ORI, HR, PI and SPOC values between groups after extubation

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Table 7: In the recovery room 1.5. and 10. minutes, measured MAP, HR, SpO2 values.

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Figure 2: SPOC values between groups

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   Discussion Top


Oxygenation and depth of anesthesia are of main concern in low-flow anesthesia procedures. In our study, the adequate depth of anesthesia was maintained with BIS monitoring throughout the operation, the oxygenation parameters (SpO2, ORI, SPOC, and PI) were observed to be within the safety limits, and no statistically significant difference was found between the two groups. The high SPOC value in the T1 group was attributed to the changes in hemoglobin levels [Table 1].

Oterkus et al.[7] used 1 L/min FGF in laparoscopic bariatric surgery and found it to be similar to high flow in terms of adequacy of tissue perfusion, depth of anesthesia, and postoperative recovery. Similar to procedures reported in the literature, it was paid attention not to exceed the safety limits of oxygenation parameters (SpO2, ORI, SPOC) in our study.

Akbas et al.[8] investigated the effects of 0.75 L/min FGF and normal-flow anesthesia on the depth of anesthesia in morbidly obese patients during laparoscopic bariatric surgery, and their results did not show a significant clinical difference between the two groups. Hemodynamic parameters of all the patients included in the study were stable intraoperatively. In terms of hemodynamic indicators recorded in the recovery room, rec1 min-HR, rec5 min-SpO2, rec5 min-MAP were more stable in the T1 group, rec10 min-MAP, rec10 min-SpO2, and rec10 min-HR were also more stable in the T1 group compared to the T2 group, which was attributed to the physiological benefits of LFA. Thus, the duration of PACU was observed to be shorter in the LFA group.

In order to prevent overdose of inhaled anesthetic agents and hypercapnia in low-flow anesthesia and to provide adequate depth of anesthesia.[9],[10] The use of high-flow 100% O2 ventilation for 10-20 min at the beginning of low-flow anesthesia allows for the elimination of nitrogen in the blood, easier distribution of anesthetic gases into the system and easier adjustment of gas concentrations.[11],[12] Similarly, in our study, 100% O2 ventilation was administered for 10 min, N2O was not used, and end-tidal CO2 could be maintained around 30-35 thanks to modern CO2 absorbers.[13]

The study of Colak et al.[14] calculating the amount of FGF by body weight as 10 ml/kg and 20 ml/kg reported a 43% decrease in sevoflurane consumption. Since our anesthesia device was not suitable, FGF could not be calculated according to body weight; however, the mean body weight of our patients in both groups was similar and was around 60-70 kg. The results of our study similarly using 1 L/min and 2.5 L/min FGF showed a reduction of up to 50% in sevoflurane consumption, considering the operative times of the groups. Thus, a significant reduction was achieved in cost.[15] Since the main determinant of the amount of gas entering the waste gas system is the amount of FGF, the health risks of the operating room personnel also decreased. A study comparing pediatric anesthetists with other anesthetists found higher spontaneous abortion rates in pediatric anesthetists as they were exposed to waste anesthetic gases more.[16]

Another important issue that prevails in terms of ecological balance related to inhaled agents is the effects of atmospheric greenhouse gases caused by all volatile agents, especially desflurane.[17],[18] Therefore, anesthetists avoid high FGF nowadays and tend toward low-flow anesthesia procedures.[18],[19] The gases accumulated in the waste gas system are sent from the operating room to the atmosphere and the main determinant of the amount of gas accumulated in the waste gas system is the amount of fresh gas flow. For this reason, measures to reduce the amount of waste and environmental effects of anesthetic gases focus on the amount of fresh gas flow.[19] We can emphasize that LFA is safer in terms of both cost and environmental contamination in today's world where patients receive the same level of anesthesia in LFA procedures, and in fact, modern anesthesia devices are safer with their advanced warning and sensor systems.[20] It is the ethical obligation of all anesthesiologists to minimize the harmful effect of anesthesia practice on environmental sustainability.[21]

Our study had some limitations. The sensor and warning systems of our anesthesia device did not allow us to adjust the FGF amount below 1 L/min and by body weight, and circuit leaks were inevitable. However, we were able to minimize the amount of leak gas with the advanced sensors and warning systems of modern anesthesia devices.


   Conclusion Top


The use of low-flow anesthesia in appropriate cases with our advanced technology anesthesia devices and monitors with superior safety equipment, which we have today, is a logical option for our environment, nature, future, and costs. In our study, we administered 1 L/min FGF to patients undergoing laparoscopic cholecystectomy without deviation from safety limits and observed about 50% lower sevoflurane consumption compared to 2.5 L/min FGF. Therefore, we concluded that low-flow anesthesia can be used safely in patients undergoing laparoscopic cholecystectomy. Nevertheless, there is a need for further studies on this subject in different cases.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Akbas S, Ozkan AS. Comparison of effects of low-flowand normal-flow anesthesia on cerebral oxygenation and bispectralindex in morbidly obese patients undergoing laparoscopic sleeve gastrectomy: A prospective, randomized clinical trial. Wideochir Inne Tech Maloinwazyjne 2019;14:19-26.  Back to cited text no. 8
    
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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]



 

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