High-flow Sevoflurane Research Articles

The effect of low flow anesthesia with sevoflurane on oxidative status: A prospective, randomized study.

Objectives:To assess the impact of low-flow, mid-flow, and high-flow sevoflurane anesthesia on the oxidative state by measuring thiol/disulfide levels in patients undergoing surgery.Methods:The study included 99 patients randomly assigned to 3 groups. In the low-flow anesthesia group, the fresh gas flow was diminished to 1 L.min-1 for anesthesia maintenance after 6 L.min-1 was administered for the first 10 minutes. In the mid-flow anesthesia group, fresh gas flow was applied as 2 L.min-1. In the high-flow anesthesia group, the fresh gas flow was administered as 4 L.min-1 throughout the operation. Blood samples were obtained before induction, at the 60th minute after induction, and at 2 hours postoperatively. Native thiol, total thiol, disulfide analyzed and disulfide/native thiol percentage, disulfide/total thiol percentage, and native thiol/total thiol percentage were calculated.Results:Disulfide values in mid-flow and low-flow anesthesia were significantly lower at the 60th minute after induction compared to the high-flow anesthesia group. In the group evaluations, intraoperative native thiol levels in the high-flow group were found to be substantialy lower than preoperative values.Conclusion:It was sighted that low-flow anesthesia with sevoflurane prohibited oxidative damage. It was concluded that low flow anesthesia can be utilized safely in this respect.

Cost identification analysis of general anesthesia.

Background and Aims:Rising health costs are challenging anesthesiologists to search for cost-effective anesthetic techniques. We conducted a study to estimate variable cost per case and cost of drug wastage as percentage of total drug cost associated with different modalities of general anesthesia (GA).Material and Methods:This prospective study was carried out after approval by institutional ethical committee in 258 adult patients aged 18–60 years of either sex, American Society of Anesthesiologists physical status I or II, with a surgical duration of 1–4 hours, posted for elective surgery under GA with endotracheal intubation. At the end of surgery, total utilization of each drug, anesthetic gases, and consumables were noted and remaining drug was regarded as wastage. Cost was recorded as per maximum retail price for that particular brand in the market at start of study and total cost was calculated. For purpose of analysis, cases were divided into low flow sevoflurane, high flow sevoflurane, high flow isoflurane, low flow isoflurane, and total intravenous anesthesia (TIVA).Results:The mean variable cost was highest with TIVA (₹2713.82 ± 509.57) and lowest with low flow isoflurane (₹1981.62 ± 335.03; P < 0.001). Drug wastage was 13.1% overall, with highest in low sevoflurane group and lowest in TIVA.Conclusion:Low flow anesthesia with isoflurane is more cost-effective as compared to high flow techniques and TIVA even for short duration surgeries. Rational use of drugs and consumables and minimizing wastage can further reduce anesthesia costs.

Effects of Low-Flow Sevoflurane Anesthesia on Pulmonary Functions in Patients Undergoing Laparoscopic Abdominal Surgery

Objective. The aim of this prospective, randomized study was to investigate the effects of low-flow sevoflurane anesthesia on the pulmonary functions in patients undergoing laparoscopic cholecystectomy. Methods. Sixty American Society of Anesthesiologists (ASA) physical status classes I and II patients scheduled for elective laparoscopic cholecystectomy were included in the study. Patients were randomly allocated to two study groups: high-flow sevoflurane anesthesia group (Group H, n = 30) and low-flow sevoflurane anesthesia group (Group L, n = 30). The fresh gas flow rate was of 4 L/min in high-flow sevoflurane anesthesia group and 1 L/min in low-flow sevoflurane anesthesia group. Heart rate (HR), mean arterial blood pressure (MABP), peripheral oxygen saturation (SpO2), and end-tidal carbon dioxide concentration (ETCO2) were recorded. Pulmonary function tests were performed before and 2, 8, and 24 hours after surgery. Results. There was no significant difference between the two groups in terms of HR, MABP, SpO2, and ETCO2. Pulmonary function test results were similar in both groups at all measurement times. Conclusions. The effects of low-flow sevoflurane anesthesia on pulmonary functions are comparable to high-flow sevoflurane anesthesia in patients undergoing laparoscopic cholecystectomy.

The Effects of Prolonged Minimal-flow Sevoflurane Anesthesia on Postoperative Hepatic and Renal Function

Background: Minimal-flow and low-flow anesthesia provide many advantages, including reduced costs and pollution, and conservation of body heat and airway humidity. However, low-flow sevoflurane anesthesia is associated with an increase in the circuit concentration of compound A, which causes nephrotoxicity in rats. Therefore, this study was conducted to assess the effects of prolonged minimal-flow sevoflurane anesthesia on hepatic and renal function. Methods: Forty female patients who underwent free flap surgery lasting more than 8 hours randomly received either high-flow (5 L/min) or minimal-flow (0.5 L/min) sevoflurane anesthesia. Hepatic functions were then assessed by measuring the serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total bilirubin levels. In addition, renal functions were assessed by measuring the blood urea nitrogen (BUN) and serum creatinine levels and by spot urinalysis. Venous blood and spot urine samples were obtained prior to administration of the anesthesia, and then on the first, third and fifth days following administration of the anesthesia. Results: The anesthetic time (9.9 ± 1.7 vs. 9.6 ± 2.0 h) and sevoflurane exposure (8.2 ± 1.7 vs. 7.4 ± 1.9 MAC-h) were not different between the high-flow and minimal-flow anesthesia group. The serum AST, ALT, ALP and total bilirubin levels were within the normal range throughout the study period in both groups. Additionally, the BUN and serum creatinine levels were within the normal range throughout the study period in both groups. Furthermore, there were no significant differences in any hepatic or renal biomarkers between the two groups. Conclusions: No significant differences in postoperative hepatic and renal function were observed between the minimal-flow and high-flow sevoflurane anesthesia groups. (Korean J Anesthesiol 2008; 54: 501～6)

A Comparison of the Effects of Prolonged (&gt;10 Hour) Low-flow Sevoflurane, High-flow Sevoflurane, and Low-flow Isoflurane Anaesthesia on Hepatorenal Function in Orthopaedic Patients

This study compared the effects of low-flow sevoflurane, high-flow sevoflurane and low-flow isoflurane on hepatorenal function during and after more than 10 hours of anaesthesia. Twenty-five patients scheduled for elective orthopaedic surgery were categorized into three groups; low-flow sevoflurane (fresh gas flow at 1 litre/min, n = 9), high-flow sevoflurane (5 l/rmin, n = 7), or low-flow isoflurane (1 l/min, n=9). Inspiratory compoundA concentrations were measured. The groups had similar duration of anaesthesia and exposure to anaesthetic agents. The area under the curve of concentration (mean, SD) of compound A in the low-flow sevoflurane group (359.8, 106.1 ppm.h) was greater than that in the high-flow sevoflurane group (61.1, 29.3 ppm.h; P<0.01). All groups showed normal plasma creatinine and creatinine clearance, and transient postoperative increases in plasma alanine aminotransferase and alpha glutathione-S-transferase, as well as urinary glucose and alpha glutathione-S-transferase, with no significant differences between groups. There were no significant relationships between the area under the curve of concentration of compound A and the biomarkers. These findings suggest that prolonged anaesthesia with low-flow sevoflurane has similar effects on hepatorenal function to prolonged anaesthesia with high-flow sevoflurane and low-flow isoflurane.

Anesthesia and renal disease

To present and interpret the relevant research (Jan 2001-Feb 2002) which has the most important implications for clinical anesthesiology as regards the prevention of perioperative renal dysfunction and the anesthetic management of patients with renal disease. Prolonged sevoflurane anesthesia with fresh gas flow less than 1 l min is unlikely to lead to clinically significant renal injury. When used as maintenance agents for patients undergoing coronary artery bypass grafting, sevoflurane anesthesia at a fresh gas flow of 3 l min, isoflurane and propofol are associated with similar rates of postoperative renal dysfunction. Less compound A is produced with smaller soda lime containers. High flow sevoflurane anesthesia (fresh gas flow of 4-6 l min) in combination with perioperative ketorolac is unlikely to lead to renal injury. Chronic treatment with angiotensin-converting enzyme inhibitors is associated with an increased incidence of postoperative renal impairment in patients undergoing elective aortic surgery. Thoracic epidural anesthesia and postoperative analgesia are associated with a decreased incidence of renal failure in patients undergoing coronary artery bypass grafting. Compared with open surgical repair, endovascular repair of aortic aneurysm is associated with less renal injury. Sevoflurane anesthesia at low or high fresh gas flow rates is probably no more injurious to the kidneys than other commonly used maintenance agents. Chronic angiotensin-converting enzyme inhibition may increase perioperative renal dysfunction. The use of thoracic epidural anesthesia and analgesia may reduce the incidence of postoperative renal failure.

Compound A: toxicology and clinical relevance

Sevoflurane, like all currently used volatile anaesthetics, is degraded by carbon dioxide absorbents. The most significant degradant is a haloalkene known trivially as "compound A". Compound A is nephrotoxic in rats and, at higher doses, in nonhuman primates, causing proximal tubular necrosis. There has been much interest in the potential for compound A toxicity in humans. Inhaled compound A concentrations are greatest at low flow rates, high sevoflurance concentrations, warmer absorbent, barium hydroxide vs soda lime, and drier absorbent. Typical inspired compound A concentrations during low-flow and closed-circuit sevoflurane anaesthesia in humans are 8-24 and 20-32 ppm with soda lime and barium hydroxide lime, respectively. Renal effects of compound A production during sevoflurane anesthesia have been examined in surgical patients and volunteers, using standard (creatinine clearance, serum BUN and creatinine) and experimental (urine excretion of protein, glucose, NAG, GST, AAP) markers of renal function. Investigations to date in surgical patients show similar renal effects of low-flow sevoflurane, low-flow isoflurane or high-flow sevoflurane. There have been no case reports of compound A-associated renal injuryin humans. In volunteers, one study found changes in experimental but not conventional renal markers, while other investigations show no significant changes in either standard or experimental markers. The mechanism of compound A nephrotoxicity in rats appears to involve metabolism to glutathione and cysteine conjugates, and their subsequent renal uptake and metabolism by pathways that are different in rats and humans.