Low-flow Anesthesia Research Articles

SOME ASPECTS OF ANESTHETIC MANAGEMENT AND POSTOPERATIVE INTENSIVE THERAPY IN PATIENTS SUBJECTED TO KIDNEY AUTOTRANSPLANTATION DURING SURGERY FOR RETROPERITONEAL SARCOMA

The article presents a retrospective analysis of anesthesia and postoperative period of five patients to whom was used autotransplantation of the kidney as a component of an operation of removing of the retroperitoneal sarcoma. To all patients were used anesthesia according to modern concepts of multimodal anesthesia based on low-flow anesthesia with Sevoflurane, thoracic epidural analgesia with Narupin and intravenous administration of Fentanyl. The following indicators were analyzed: doses of anesthetics, hemodynamic parameters, the volume of intraoperative infusion therapy, the volume of diuresis during the operation and in the postoperative period, the duration of postoperative administration of anticoagulants, the use of antibacterial drugs, the days of patients in the intensive care unit and the number of bed days spent in Hospital. It has been shown once again that the combination of low flow anesthesia with Sevoflurane, thoracic epidural analgesia with Narupin and intravenous administration of Fentanyl is a priority in the anesthetic support of such operations. Number of bed-days spent in intensive care and inpatient. Decreases with the improvement of both surgical techniques, both intra- and postoperative management of patients.

Low-flow anaesthesia – underused mode towards “sustainable anaesthesia”

Any technique that employs a fresh gas flow that is less than the alveolar ventilation can be classified as low-flow anaesthesia. The complexities involved in the calculation of uptake of anaesthetic agents during the closed-circuit anaesthesia made this technique less popular. However, the awareness of the dangers of theatre pollution with trace amounts of the anaesthetic agents and the prohibitively high cost of the new inhalational agents, have helped in the rediscovery of low-flow anaesthesia. Moreover, the time has arrived for each of us, the practicing anaesthesiologists, to move towards the practice of low-flow anaesthesia, to achieve lesser theatre and environmental pollution and also to make anaesthesia more economical. The article also reviews low-flow anaesthesia (LFA) in paediatrics, recent advances such as automated LFA and updates on currently undergoing research to retrieve and reuse anaesthetic agents.

Advantages of 1-1-12 Wash in Scheme during Induction with Low Flow Anesthesia with and without Nitrous Oxide.

Introduction:In the past, many wash-in schemes have been used with initially high fresh gas flow (FGF) to achieve the necessary alveolar concentration of inhalational agent in 10–15 min. This study was designed to show whether 1-1-12 wash-in scheme proposes an earlier achievement of induction or is there any requirement of high FGF phase to know the time taken for induction with and without nitrous oxide (N2O).Aims:The aim of the study was to find out the time required for the alveolar concentration of desflurane to be from 1% to 6% with and without N2O.Design:It was a potential randomized study which was conducted on sixty patients admitted for elective surgery.Materials and Methods:Two groups of thirty patients each were made and randomly assigned. Group N received desflurane with N2O plus oxygen and Group A received desflurane with air plus oxygen.Statistical Analysis:The observations were noted and evaluated accordingly. Analysis was done using unpaired t-test.Results:Hemodynamic parameters were almost similar in both the groups. In Group N, gradual FAD (Alveolar Desflurane concentration, i.e., end-tidal desflurane) from 1% to 6% was achieved at 0.5, 1, 1.5, 2, 3, and 4 min. In Group A, the same was achieved at 0.6, 1, 1.5, 2, 3, and 4 min (P > 0.05). No significant difference was found between the recuperation time and score in both the groups. Rather complications were more in Group N and statistically significant for nausea and vomiting.Conclusion:Time taken to attain FAD from 1% to 6% was 4 min in both the groups. It is concluded that the recitation of 1-1-12 wash-in scheme is autonomous on the use of N2O and high FGF phase.

Low flow practice for laparoscopic colorectal surgery in pediatric patients

Low flow anaesthesia and laparoscopic techniques in pediatric patients are two of many developments in the modern medical field. Both techniques were established to support environmentally friendly, safe, and comfortable anaesthesia practices for patients. Presented in this case series, laparoscopy was done in all three cases (two digestive cases, and one urology case). All three cases were performed with general anaesthesia using the low flow anaesthesia technique with volatile sevoflurane combined with caudal block regional anaesthesia. In all cases, no morbidity was found after anaesthesia or surgery to influence the patient's outcome. Improvements in the outcome of pediatric patients were seen using the low flow anaesthesia techniques. These improvements include a significant reduction of volatile used, faster wake up times, and reduction of agitation after anaesthesia.

Effects of Total Intravenous Anesthesia and Low- and High-Flow Anesthesia Implementation on Middle Ear Pressure.

Background The middle ear is an air-filled lacuna in the temporal bone. Inhaled anesthetic agents increase the pressure of this lacuna. Therefore, attention must be paid in choosing not only anesthetic agents but also anesthetic method. Aim This study compared the effects of high-flow total intravenous anesthesia (TIVA) and low- and high-flow desflurane anesthesia on middle ear pressure. Study Design Randomized prospective double-blind study. Methods In this retrospective double-blind study, 90 patients (20–65 years old) scheduled to undergo elective thyroidectomies were divided into three randomized anesthesia groups: high-flow desflurane (Group I), low-flow desflurane (Group II), and high-flow TIVA (propofol, remifentanil) (Group III). The hemodynamic and respiratory parameters and tympanometry were measured before induction (T1), 10 minutes after intubation (T2), 10 minutes before the end of the operation (T3), and 5 (T4), 10 (T5), 15 (T6), and 30 (T7) minutes after the operation. Results No statistically significant differences were found in the age, gender, weight, height, body mass index, surgery duration, and anesthetic duration (p > 0.05). There were no statistically significant differences at T1, T3, T4, T5, T6, and T7 (p > 0.007), but there was a significant difference at T2 (p < 0.001), with Groups II and III having lower pressure than Group I (p < 0.001). Conclusion The high-flow desflurane group had higher postinduction middle ear pressure values. Therefore, low-flow anesthesia and TIVA can be used more safely in middle ear surgeries, provided that a well-equipped anesthetic device and appropriate monitoring conditions are available.

Prevention of cognitive dysfunction in elderly cancer patients operated on the pelvic organs in conditions of multimodal anesthesia

A study was conducted in 76 elderly patients aged 62 to 84 years with an increased risk of developing POCD. Of these, 46 women and 30 men. Patients were divided into two groups, depending on the type of anesthesia. The 1st group consisted of 37 patients who had low-flow anesthesia with sevoflurane combined with epidural analgesia. 2nd - 39 patients who had anticipated multimodal analgesia on the basis of systemic administration of lidocaine, sulphate magnesia, verapamil. In each group, patients are divided into subgroups - the main (O) and control (K). In the main subgroups anesthetics were supplemented with 20 ml. Cytoflavin, administered 20-25 minutes before the end of surgery and on the 1-3 days of the perioperative period. Cognitive functions were assessed by standardized scales: Mini Mental State Examination (MMSE), Montreal Cognitive Evaluation Scale (MoCA), Frontal Assessment Batteries (FAB). The level of anxiety and depression was determined by the hospital scale of anxiety and depression (HADS). At oncological patients of advanced age in 52.5% of cases there is a moderate degree of cognitive impairment. In the perioperative period, in the study groups, when using different variants of multimodal anesthesia, there is an equivalent transient decrease in cognitive functions by 12.5 and 12.8%. The use of cytoflavin can reduce the manifestation of POCD from 1-day perioperative period, improve the cognitive status of patients. In cancer patients of advanced age, cognitive impairment is observed, aggravated after surgical treatment, regardless of the variant of multimodal anesthesia. Protection by Cytoflavin allows to restore the cognitive functions of elderly cancer patients, reduce the manifestations of POCD.

Effect of Low-flow Sevoflurane Anaesthesia on Renal Functions in Patients Undergoing Surgery: A Retrospective Study

Effect of Low-flow Sevoflurane Anaesthesia on Renal Functions in Patients Undergoing Surgery: A Retrospective Study

A Questionnaire Survey on use of Low Flow Anesthesia by Anesthesiologists

A Questionnaire Survey on use of Low Flow Anesthesia by Anesthesiologists

The impact of fresh gas flow on wash-in, wash-out time and gas consumption for sevoflurane and desflurane, comparing two anaesthesia machines, a test-lung study.

Low-flow anaesthesia is considered beneficial for the patient and the environment, and it is cost reducing due to reduced anaesthetic gas consumption. An initial high-flow to saturate the circle system ( wash-in) is desirable from a clinical point of view. We measured the wash-in and wash-out times (time to saturate and to eliminate the anaesthetic agent, AA), for sevoflurane and desflurane, in a test-lung with fixed 3 MAC vaporizer setting at different fresh gas flow (FGF) and calculated the consumption of AA. We tried to find an optimal flow rate for speed and gas consumption, comparing two anaesthesia machines (AMs): Aisys and Flow-i. Time to reach 1 minimal alveolar concentration (MAC) (wash-in) decreased (p&lt;0.05) at higher flow rates (1 – 2 – 4) but plateaued at 4-4.8 l/min. The consumption of AA was at its lowest around 4-4.8 l/min (optimal flow) for all but the Aisys /desflurane group. Wash-out times decreased as FGF increased, until reaching plateau at FGF of 4-6 l/min. Aisys had generally shorter wash-in times at flow rates &lt; 4 l/min as well as lower consumption of AA. At higher flow rates there were little difference between the AMs. The “optimal FGF” for wash-out, elimination of gas from the test-lung and circle system, plateaued with no increase in speed beyond 6 l/min. A fresh gas flow of 4 l/min. seems “optimal” taking speed to reach a 1 MAC ET and gas consumption into account during wash-in with a fixed 3 MAC vaporizer setting, and increasing fresh gas flow beyond 6 l/min does not seem to confirm major benefit during wash-out.

The impact of fresh gas flow on wash-in, wash-out time and gas consumption for sevoflurane and desflurane, comparing two anaesthesia machines, a test-lung study.

Low-flow anaesthesia is considered beneficial for the patient and the environment, and it is cost reducing due to reduced anaesthetic gas consumption. An initial high-flow to saturate the circle system ( wash-in) is desirable from a clinical point of view. We measured the wash-in and wash-out times (time to saturate and to eliminate the anaesthetic agent, AA), for sevoflurane and desflurane, in a test-lung with fixed 3 MAC vaporizer setting at different fresh gas flow (FGF) and calculated the consumption of AA. We tried to find an optimal flow rate for speed and gas consumption, comparing two anaesthesia machines (AMs): Aisys and Flow-i. Time to reach 1 minimal alveolar concentration (MAC) (wash-in) decreased (p<0.05) at higher flow rates (1 – 2 – 4) but plateaued at 4-4.8 l/min. The consumption of AA was at its lowest around 4-4.8 l/min (optimal flow) for all but the Aisys /desflurane group. Wash-out times decreased as FGF increased, until reaching plateau at FGF of 4-6 l/min. Aisys had generally shorter wash-in times at flow rates < 4 l/min as well as lower consumption of AA. At higher flow rates there were little difference between the AMs. The “optimal FGF” for wash-out, elimination of gas from the test-lung and circle system, plateaued with no increase in speed beyond 6 l/min. A fresh gas flow of 4 l/min. seems “optimal” taking speed to reach a 1 MAC ET and gas consumption into account during wash-in with a fixed 3 MAC vaporizer setting, and increasing fresh gas flow beyond 6 l/min does not seem to confirm major benefit during wash-out.

The impact of fresh gas flow on wash-in, wash-out time and gas consumption for sevoflurane and desflurane, comparing two anaesthesia machines, a test-lung study.

Low-flow anaesthesia is considered beneficial for the patient and the environment, and it is cost reducing due to reduced anaesthetic gas consumption. An initial high-flow to saturate the circle system ( wash-in) is desirable from a clinical point of view. We measured the wash-in and wash-out times (time to saturate and to eliminate the anaesthetic agent, AA), for sevoflurane and desflurane, in a test-lung with fixed 3 MAC vaporizer setting at different fresh gas flow (FGF) and calculated the consumption of AA. We tried to find an optimal flow rate for speed and gas consumption, comparing two anaesthesia machines (AMs): Aisys and Flow-i. Time to reach 1 minimal alveolar concentration (MAC) (wash-in) decreased (p<0.05) at higher flow rates (1 - 2 - 4) but plateaued at 4-4.8 l/min. The consumption of AA was at its lowest around 4-4.8 l/min (optimal flow) for all but the Aisys /desflurane group. Wash-out times decreased as FGF increased, until reaching plateau at FGF of 4-6 l/min. Aisys had generally shorter wash-in times at flow rates < 4 l/min as well as lower consumption of AA. At higher flow rates there were little difference between the AMs. The "optimal FGF" for wash-out, elimination of gas from the test-lung and circle system, plateaued with no increase in speed beyond 6 l/min. A fresh gas flow of 4 l/min. seems "optimal" taking speed to reach a 1 MAC ET and gas consumption into account during wash-in with a fixed 3 MAC vaporizer setting, and increasing fresh gas flow beyond 6 l/min does not seem to confirm major benefit during wash-out.

Circle systems and low-flow anaesthesia

Circle systems and low-flow anaesthesia

Comparison Between Cuff Pressures of Endotracheal Tubes Inflated with Saline or Air in Low-Flow Anesthesia

Amac: Entube hastalarda nitrik oksitli (N2 O) dusuk akimli genel anestezide (DAA) inspire edilen nitroz oksit fraksiyonundaki (Fi N2 O) artisa bagli olarak N2 O’nun endotrakel tup (ETT) kafi icine diffuzyonu kaf basinclarinda artisa neden olur. Biz calismamizda N2 O’lu DAA’de hava ve salin ile sisirilen ETT kaf basinclarini ve bunun ameliyat sonrasi donemdeki bogaz agrisina olan etkisini karsilastirdik. Yontemler: Calismaya ASA I/II toplam altmis eriskin hasta dahil ettik. Anestezi induksiyonu sonrasi endotrakeal entubasyon yapilan hastalarin ETT kaflari hava (Grup A, n=30) ve salin (Grup S, n=30) ile 25 cmH2 O olacak sekilde sisirilerek rastgele iki gruba ayrildi. Anestezi N2 O’li DAA ile surduruldu. ETT kaf basinclari bir basinc manometresi ile surekli olarak olculdu ve inspire edilen oksijen ve N2 O seviyeleri operasyon boyunca her 10 dakikada bir kaydedildi. Hastalarin cerrahi sonrasi 2. ve 24. saatlerde yutkunurken ve yutkunma olmaksizin bogaz agrilari numerical rating scala (NRS) ile degerlendirildi. Bulgular: Gruplar arasinda demografik ve intraoperatif acisindan anlamli bir fark yoktu. Tum takip donemlerindeki kaf basinclari Grup S ile kiyaslandi- ginda Grup A’da maksimum olarak yuksekti (p10.dk=0,02, deger donemlerde p<0,0001). Grup A’da kaf basinclari ile FiN2O arasinda %51,9 pozitif yonde anlamli bir korelasyon bulundu (r=0,519, p=0,048). Gruplarin yutkunma ve yutkunma olmaksizin postoperatif bogaz agrisi skorlari kiyaslandiginda, Grup A, Grup S'ye gore 2. ve 24. saatte anlamli olarak yuksekti (p<0,05). Sonuc: Azotprotoksitli DAA’de ETE tup kaflarinin hava ile kiyaslandiginda salin ile sisirilmesi intraoperatif kaf basinclarini ve cerrahi sonrasi donemde bogaz agrisi sikligini azaltmistir.

Prospects of minimally invasive methods of anesthesia for laparoscopic bariatric interventions in patients with morbid obesity, according to the principle of accelerated rehabilitation

This clinical article presents clinical examples of the successful implementation of the program for accelerated management of the postoperative period in patients with morbid obesity after laparoscopic stomach longitudinal resection , using combined anesthesia based on intravenous administration of propofol, inhalation low flow anesthesia with sevoflurane, and peri operative multimodal analgesia.The objective. Was optimization of methods of general anesthesia of bariatric surgical interventions in patients with morbid obesity.Patients and methods. 26 patients with a BMI of 36-45 took part in the study, who underwent laparoscopic stomach longitudinal resection with the use of combined low flow anesthesia with sevoflurane and multimodal analgesia. All patients underwent the concept of minimally invasive intraoperative anesthetic monitoring and an accelerated postoperative rehabilitation program.Results. The dynamics of the values of central hemodynamics showed a high hemodynamic stability at all stages of the operation, with a tendency towards normalization of initially elevated blood pressure. The indices of the adequacy of oxygenation and ventilation (SpO2 and EtCO2) corresponded to normal values and did not differ from the level of stress norm. In all patients, recovery of spontaneous breathing occurred on average 8 minutes after the end of the operation. Extubation was performed on the operating table in 8±2 minutes (p=0,05), therefore, prolonged artificial ventilation was not required. At that, the level of postoperative pain on the operating table by VAS was minimal – 0–2 points. In the early postoperative period, the pain level according to the VAS in patients was on average 3±2 points (p=0.05). Accordingly, there was no need for narcotic analgesics. All patients were activated within the first 24 hours after the operation. Patients were discharged on 2,9±0,25 days after the operation (p=0,05).Conclusion. Inhalation low flow anesthesia based on sevoflurane with the use of multimodal analgesia during laparoscopic stomach longitudinal resection in patients with morbid obesity does not require prolonged ventilation and is a worthy alternative to combined epidural anesthesia. Rejection of invasive monitoring allows early activation of patients and a shortened stay in the hospital.

Emergence and Recovery Characteristics After Low Flow Anaesthesia With Desflurane and Sevoflurane in Cancer Patients Administered Combined Epidural and General Anaesthesia

Emergence and Recovery Characteristics After Low Flow Anaesthesia With Desflurane and Sevoflurane in Cancer Patients Administered Combined Epidural and General Anaesthesia

Wash-in and wash-out of sevoflurane in a test-lung model: A comparison between Aisys and FLOW-i

Background:Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia. Methods:We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA) and FLOW-i (Maquet, Solna, Sweden) in a test lung model. Results: We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1%) decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/min. to less than a minute at constant 4 L/min (17 ± 11 seconds), without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min. Conclusions: Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.

Comparison of Effects of Low-Flow Sevoflurane and Low-Flow Desflurane Anaesthesia on Renal Functions Using Cystatin C.

Numerous studies have indicated nephrotoxic effects of sevoflurane because of its two bioproducts compound A and fluoride. Cystatin C (CyC) is a more sensitive biomarker than creatinine to show early and mild changes in kidney function. We designed this prospective randomised study to compare the effects of low-flow sevoflurane anaesthesia and low-flow desflurane anaesthesia on renal functions based on CyC levels. No studies have evaluated the effects of low-flow sevoflurane anaesthesia on renal functions based on CyC levels to date. Thirty American Society of Anesthesiologists (ASA) physical status I-II patients who were scheduled for urological procedures were enrolled in this study. The patients were randomly assigned to 2 groups: low-flow sevoflurane anaesthesia or low-flow desflurane anaesthesia. Serum urea, creatinine and CyC levels were measured before the operation, just before extubation and 24 h after the operation. Creatinine clearance was calculated in the first 24-h urine sample. There were no significant differences in serum urea, creatinine and CyC levels or 24 h creatinine clearance between the groups. Our study demonstrates with a more sensitive biomarker, CyC, that low-flow sevoflurane anaesthesia is safe in terms of the effects on renal function.

Wash-in and wash-out of sevoflurane in a test-lung model: A comparison between Aisys and FLOW-i

Background: Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia. Methods: We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA) and FLOW-i (Maquet, Solna, Sweden) in a test lung model. Results: We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1%) decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/min. to less than a minute at constant 4 L/min (17 ± 11 seconds), without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min. Conclusions: Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.

Wash-in and wash-out of sevoflurane in a test-lung model: A comparison between Aisys and FLOW-i.

Background: Modern anaesthesia workstations are reassuringly tight and are equipped with effective gas monitoring, thus providing good opportunities for low/minimal flow anaesthesia. A prerequisite for effective low flow anaesthesia is the possibility to rapidly increase and decrease gas concentrations in the circle system, thereby controlling the depth of anaesthesia. Methods: We studied the wash-in and wash-out of sevoflurane in the circle system with fixed fresh gas flow and vaporizer setting. We compared two modern anaesthesia work stations, the Aisys (GE, Madison, WI, USA) and FLOW-i (Maquet, Solna, Sweden) in a test lung model. Results: We found fresh-gas flow to have, as expected, a major influence on wash-in, as well as wash-out of sevoflurane. The wash-in time to reach a stable circle 1 MAC (2.1%) decreased from an average of 547 ± 83 seconds with a constant fresh gas flow of 300 ml/min and vaporizer setting of 8%, to a mean of 38 ± 6 seconds at a fresh gas flow of 4 L/min. There were only minor differences between the two works-stations tested; the Aisys was slightly faster at both 300 and 4 L/min flow. Time to further increase circle end-tidal concentration from 1-1.5 MAC showed likewise significant associations to fresh gas and decreased from 330 ± 24 seconds at 300 ml/L to less than a minute at constant 4 L/min (17 ± 11 seconds), without anaesthetic machine difference. Wash-out was also fresh gas flow dependent and plateaued at 7.5 L/min. Conclusions: Circle system wash-in and wash-out show clear fresh gas dependency and varies somewhat between the Aisys and Flow-i. The circle saturation, reaching 1 MAC end-tidal or increasing from 1-1.5 MAC can be achieved with both work-stations within 1.5 minutes at a constant fresh gas flow of 2 and 4 L/min. Wash-out plateaued at 7.5 L/min.

The Humidity in a Low-Flow Dräger Fabius Anesthesia Workstation with or without Thermal Insulation or a Heat and Moisture Exchanger: A Prospective Randomized Clinical Trial.

BackgroundDuring anesthesia, as compared with intensive care, the time of the tracheal intubation is much shorter. An inhaled gas minimum humidity of 20 mgH2O.L-1 is recommended to reduce the deleterious effects of dry gas on the airways during anesthesia with tracheal intubation. The Fabius GS Premium® anesthesia workstation (Dräger Medical, Lübeck, Germany) has a built-in hotplate to heat gases in the breathing circuit. A heat and moisture exchanger (HME) is used to further heat and humidify the inhaled gas. The humidity of the gases in the breathing circuit is influenced by the ambient temperature. We compared the humidity of the inhaled gases from a low-flow Fabius anesthesia workstation with or without thermal insulation (TI) of the breathing circuit and with or without an HME.MethodsWe conducted a prospective randomized trial in 41 adult female patients who underwent elective abdominal surgery. The patients were allocated into four groups according to the devices used to ventilate their lungs using a Dräger Fabius anesthesia workstation with a low gas flow (1 L.min-1): control, with TI, with an HME or with TI and an HME (TIHME). The mean temperature and humidity of the inhaled gases were measured during 2-h after connecting the patients to the breathing circuit.ResultsThe mean inhaled gas temperature and absolute humidity were higher in the HME (29.2±1.3°C; 28.1±2.3 mgH2O·L-1) and TIHME (30.1±1.2°C; 29.4±2.0 mgH2O·L-1) groups compared with the control (27.5±1.0°C; 25.0±1.8 mgH2O·L-1) and TI (27.2±1.1°C; 24.9±1.8 mgH2O·L-1) groups (P = 0.003 and P<0.001, respectively).ConclusionsThe low-flow Fabius GS Premium breathing circuit provides the minimum humidity level of inhaled gases to avoid damage to the tracheobronchial epithelia during anesthesia. TI of the breathing circuit does not increase the humidity of the inhaled gases, whereas inserting an HME increases the moisture of the inhaled gases closer to physiological values.