Renal function in patients with high serum fluoride concentrations after prolonged sevoflurane anesthesia

Incidence of genitourinary anomalies in congenital scoliosis: systematic review and meta-analysis

PURPOSE

The main objective of this study was to assess the overall incidence of genitourinary anomalies in patients with congenital scoliosis by providing the highest level of evidence. The secondary objective was to look for associations and trends influencing the incidence.

METHODS

A meta-analysis using PubMed, Embase, Scopus, and the Cochrane Collaboration Library database was carried out. We included studies focusing on patients with congenital scoliosis and genitourinary anomalies. The main outcome was the incidence of genitourinary anomalies in congenital scoliosis. We also collected the following data: patient gender, type of deformity (formation, segmentation, or mixed), deformity location, and associated anomalies. We included cohort studies. Data was extracted from published reports and combined using Review Manager 5.4. The quality of the included studies was assessed independently by two authors using the Methodological Index for Non-Randomized Studies (MINORS) criteria.

RESULTS

A total of eight cohort studies were included from a pool of 2781 patients. The incidence of genitourinary anomalies associated with congenital scoliosis was 22.91% (95% CI 13.39-32.43%). The incidence of surgically treated genitourinary anomalies was 13.92% (95% CI 4.54-23.31%). There were no differences related to gender (male 49.3% versus female 50.7%; p > 0.05). There were no differences regarding the type of deformity. The incidences of associated intraspinal, cardiac, musculoskeletal and craniofacial anomalies were 33.30%, 17.60%, 27.77% and 19.83% respectively. The most frequent genitourinary anomalies were: unilateral kidney (111/388); renal ectopia (50/367); obstructive uropathy (30/201), horseshoe kidney (30/313) and undescended testicle (16/180).

CONCLUSIONS

The incidence of genitourinary anomalies associated with congenital scoliosis was 22.91%, and 13.92% were surgically treated. Unilateral kidney was the most common genitourinary abnormality. There were no differences between genders and deformity types. It is important to consider the association between genitourinary anomalies and intraspinal or musculoskeletal anomalies.

Use of volatile agents for sedation in the intensive care unit: A national survey in France

Background

Current intensive care unit (ICU) sedation guidelines recommend strategies using non-benzodiazepine sedatives. This survey was undertaken to explore inhaled ICU sedation practice in France.

Methods

In this national survey, medical directors of French adult ICUs were contacted by phone or email between July and August 2019. ICU medical directors were questioned about the characteristics of their department, their knowledge on inhaled sedation, and practical aspects of inhaled sedation use in their department.

Results

Among the 374 ICUs contacted, 187 provided responses (50%). Most ICU directors (73%) knew about the use of inhaled ICU sedation and 21% used inhaled sedation in their unit, mostly with the Anaesthetic Conserving Device (AnaConDa, Sedana Medical). Most respondents had used volatile agents for sedation for <5 years (63%) and in <20 patients per year (75%), with their main indications being: failure of intravenous sedation, severe asthma or bronchial obstruction, and acute respiratory distress syndrome. Sevoflurane and isoflurane were mainly used (88% and 20%, respectively). The main reasons for not using inhaled ICU sedation were: “device not available” (40%), “lack of medical interest” (37%), “lack of familiarity or knowledge about the technique” (35%) and “elevated cost” (21%). Most respondents (80%) were overall satisfied with the use of inhaled sedation. Almost 75% stated that inhaled sedation was a seducing alternative to intravenous sedation.

Conclusion

This survey highlights the widespread knowledge about inhaled ICU sedation in France but shows its limited use to date. Differences in education and knowledge, as well as the recent and relatively scarce literature on the use of volatile agents in the ICU, might explain the diverse practices that were observed. The low rate of mild adverse effects, as perceived by respondents, and the users’ satisfaction, are promising for this potentially important tool for ICU sedation.

A Round Trip: The Japanese Contribution to the Development of Sevoflurane

Sevoflurane was first synthesized independently by Richard Wallin and Bernard Regan at Travenol Laboratories Incorporated and Ross Terrell and Louise Croix at Airco, Inc in the late 1960s, and subsequent animal studies and a phase-1 human trial of the agent published in 1981 showed promising results. Further research in the United States was halted, however, because of concerns regarding potential nephrotoxicity and the introduction of less degradable alternatives. Interest in sevoflurane resumed in Japan when Maruishi Pharmaceutical Company, Limited (Ltd) (Maruishi) decided to continue its development in 1982. They secured approval by the Japanese Ministry of Health, Labor and Welfare for its clinical use in January 1990. Because of its low blood:gas partition coefficient and resulting rapid action, sevoflurane quickly became the anesthetic of choice of Japanese anesthesiologists. In 1992 Abbott Laboratories, now AbbVie, Inc (Abbott, North Chicago, IL) finalized a licensing agreement with Maruishi to seek the US Food and Drug Administration approval for sevoflurane sales in the United States. Approved in June 1995, sevoflurane is now marketed by Abbott in 120 countries and has been administered >120 million times. This report details the Japanese contribution to the development of sevoflurane.

Perioperative risk factors for acute kidney injury after liver resection surgery: an historical cohort study

PURPOSE

This study aimed to identify the incidence and risk factors for acute kidney injury (AKI) after liver resection surgery and to clarify the relationship between postoperative AKI and outcome.

METHODS

We conducted a historical cohort study of patients who underwent liver resection surgery with sevoflurane anesthesia from January 2004 to October 2011. Acute kidney injury was diagnosed based on the Acute Kidney Injury Network classification within 72 hr after the surgery. Patient data, surgical and anesthetic data, and laboratory data were extracted manually from the patients' electronic charts. Multivariable logistic regression analysis was used to identify perioperative risk factors for postoperative AKI.

RESULTS

Acute kidney injury was diagnosed in 78 of 642 patients (12.1%; 95% confidence interval [CI]: 9.7 to 14.9). Multivariable analysis showed an independent association between postoperative AKI and preoperative estimated glomerular filtration rate (adjusted odds ratio [aOR] 0.74; 95% CI: 0.64 to 0.85), preoperative hypertension (aOR 2.10; 95% CI: 1.11 to 3.97), and intraoperative red blood cell transfusion (aOR 1.04; 95% CI: 1.01 to 1.07). Development of AKI within 72 hr after liver resection surgery was associated with increased hospital mortality, prolonged length of stay, and increased rates of mechanical ventilation, reintubation, and renal replacement therapy.

CONCLUSION

Perioperative risk factors for AKI after liver resection surgery are similar to those established for other surgical procedures. Further studies are needed to establish causality and to determine whether interventions on modifiable risk factors can reduce the incidence of postoperative AKI and improve patient outcome. This study was registered at the University Hospital Medical Information Network (UMIN) Center (UMIN 000008089).

Pharmacokinetics of fluoride in toddlers after application of 5% sodium fluoride dental varnish

The prevalence of dental caries (tooth decay) among preschool children is increasing, driven partially by an earlier age of onset of carious lesions. The American Academy of Pediatrics recommends application of 5% sodium fluoride varnish at intervals increasing with caries risk status, as soon as teeth are present. However, the varnishes are marketed for treatment of tooth sensitivity and are regulated as medical devices rather than approved by the US Food and Drug Administration for prevention of dental caries (tooth decay). The objective of this research is to examine the safety of use in toddlers by characterizing the absorption and distribution profile of a currently marketed fluoride varnish. We measured urinary fluoride for 5 hours after application of fluoride varnish to teeth in 6 toddlers aged 12 to 15 months. Baseline levels were measured on a separate day. The urine was extracted from disposable diapers, measured by rapid diffusion, and extrapolated to plasma levels. The mean estimated plasma fluoride concentration was 13 μg/L (SD, 9 μg/L) during the baseline visit and 21 μg/L (SD, 8 μg/L) during the 5 hours after treatment. Mean estimated peak plasma fluoride after treatment was 57 μg/L (SD, 22 μg/L), and 20 μg/kg (SD, 4 μg/L) was retained on average. Retained fluoride was 253 times lower than the acute toxic dose of 5 mg/kg. Mean plasma fluoride after placement of varnish was within an SD of control levels. Occasional application of fluoride varnish following American Academy of Pediatrics guidance is safe for toddlers.

Effect of sevoflurane anesthesia on the severity of renal histopathologic changes in rabbits pretreated with gentamicin: A controlled, investigator-blinded, experimental study

BACKGROUND

Inorganic fluoride and compound A are potential nephrotoxic products of sevoflurane, a halogenated inhalational general-anesthetic drug.

OBJECTIVE

The aim of this study was to microscopically examine the effect of sevoflurane on the severity of renal histopathologic changes in rabbits pretreated with gentamicin.

METHODS

In this controlled, investigator-blinded, experimental study at the Firat University School of Medicine, Elazig, Turkey, male New Zealand white rabbits (age range, 6-8 months; weight range, 2600-3400 g) were randomly divided into 4 groups of equal size. The gentamicin group received IM gentamicin 10 mg/kg · d(-1) for 10 days. Rabbits in the sevoflurane group received pH-balanced saline solution at a volume of 10 mg/kg · d(-1) for 10 days, equivalent to the volume of gentamicin administered to the gentamicin group. On day 11, anesthesia was induced with 8% sevoflurane in 50% oxygen and air using a suitable facemask. When a sufficient depth of anesthesia (loss of eyelash reflex and tolerance to tail-clamp stimuli) was reached (without a muscle relaxant), the rabbits were intubated (3-mm ID) and allowed to breathe spontaneously. End-tidal or end expiratory concentration of sevoflurane was then decreased to 4% and the rabbits were anesthetized at a flow rate of 4 L/min for 4 hours. The rabbits in the gentamicin + sevoflurane group were treated with IM gentamicin at a dosage of 10 mg/kg · d(-1) for 10 days. On day 11, they were exposed to sevoflurane, as described for the sevoflurane group. The control group received IM pH-balanced saline solution for the duration of the study. Twenty-four hours after treatment completion, all rabbits were euthanized and kidney tissue samples were obtained. Histopathologic examinations were then carried out using light microscopy. Changes in renal histopathology were based on the percentage of acute tubular necrosis (ATN) and judged on a scale from none to severe.

RESULTS

Forty male New Zealand white rabbits (mean [SD] age, 7 [0.49] months; mean [SD] weight, 2900 [150] g) were divided into 4 groups of 10 rabbits each. Proximal renal tubule cell injury in the form of ATN (the mean score) was significantly greater in the 3 treatment groups than in the control group (all, P < 0.001), especially at the corticomedullary junction. In the 3 treatment groups, the most severe renal damage observed was rated as mild (10%-25%). More rabbits in the gentamicin + sevoflurane group had mild renal damage (7) than in the gentamicin group (4) or the sevoflurane group (4), but the between-group differences were not statistically significant.

CONCLUSION

In this experimental study of the effects of sevoflurane on the severity of renal histopathologic changes, a higher percentage of rabbits were observed to have greater renal damage in the gentamicin + sevoflurane group than the other groups. However, between-group differences did not reach statistical significance.

Effect of sevoflurane on grafted kidney function in renal transplantation

BACKGROUND

The objective of this retrospective study was to determine if there are any differences in grafted kidney function in recipients of kidney transplantation (KT) when donors and recipients were anesthetized with sevoflurane compared to desflurane.

METHODS

Seventy-three pairs of donors-recipients were anesthetized with sevoflurane (Sevo group) and 71 pairs were anesthetized with desflurane (Des group). We retrospectively investigated the blood urea nitrogen (BUN) levels, creatinine (Cr) levels, and estimated glomerular filtration rates (eGFR) of the recipients in both groups for 1 year postoperatively. We tested non-inferiority for serum creatinine at discharge and 1 year after KT. Short-term (1 year) outcomes of KT were assessed by the incidence of delayed graft function (DGF), acute rejection episodes (ARE), and graft failure.

RESULTS

There were no differences in BUN, Cr, eGFR, or outcomes of KT at 1 year postoperatively. Specifically, the 95% confidence interval for the difference in creatinine levels between the Sevo and Des groups was less than the margin of equivalence at the time of discharge and 1 year after surgery. The occurrences of DGF, ARE, and graft failure were comparable between the groups.

CONCLUSIONS

Compared to desflurane, sevoflurane had no adverse effects on grafted renal function or on the short-term outcome of renal transplantation.

Biochemical Effects of Low-Flow Anesthesia with Inhalation agents in Patients undergoing Laparoscopic Surgery

This study was designed to investigate the effects of low-flow anesthesia with sevoflurane and desflurane on renal and hepatic functions in patients undergoing laparoscopic abdominal surgery. Twenty patients with ASA I or II (American Society of Anesthesiologists classification) physical scores were included in the study. There were no significant differences between sevoflurane and desflurane groups with respect to age, weight, body mass index, duration of the operation and the anesthesia. In both groups, renal function parameters such as urea, BUN, creatinine and calculated creatinine clearance did not show significant differences at 24 and 48 hours. Homocysteine levels, which showed renal metabolic function, did not change significantly at 24 and 48 hours when compared to baseline levels in both groups. Transaminases were not significantly different between the two groups from baseline to 24 and 48 hours. These differences between the preoperative and postoperative values of biochemical parameters were similar for both anesthetic groups (p>0.05). Low-flow anesthesia did not cause impairment in terms of renal and hepatic functions.

Anesthesia and renal disease

PURPOSE OF REVIEW

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.

RECENT FINDINGS

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.

SUMMARY

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.

Renal Safety and Extrahepatic Defluorination of Sevoflurane in Hepatic Transplantations

BACKGROUND

The main metabolic pathway for defluorination of sevoflurane in the liver produces inorganic fluoride (Fl). The metabolism and effect of sevoflurane on the kidney is not clear during anhepatic phase in liver transplantation. The goal of the present study was to investigate the metabolism and renal effect of sevoflurane by measuring plasma and urine inorganic fluoride, urinary N-acetyl-glucosaminidase (NAG), and plasma creatinine levels in patients undergoing liver transplantations.

METHODS

After institutional approval and informed consent, we studied nine cases of orthotopic liver transplantation after anesthesia was induced with 5 mg . kg(-1) thiopental, 1 mug . kg(-1) fentanyl intravenously, the trachea was intubated after vecuronium bromide 0.1 mg . kg(-1). Anesthesia was maintained with sevoflurane (2%), O(2), and N(2)O at a total gas flow of 6 L . min(-1) using a semiclosed circle system with a sodalime canister. Blood and urine samples were obtained to measure plasma and urine fluoride concentrations and urinary NAG excretions before induction (P0), hourly during resection (P1, P2, P3), every 15 minutes during anhepatic phase (A1, A2, A3), hourly after reperfusion (neohepatic phase) (N1, N2, N3), and postoperative first hour (Po1). Preoperative (T0) and postoperative day 1 (T1), 3 (T3), 7 (T7) plasma blood urea nitrogen (BUN) and creatinine (Cr) levels were also recorded.

RESULTS

Mean duration of surgery was 9:06 +/- 0:09 hours. Mean inorganic fluoride concentrations in plasma were in the range of 0.71 +/- 0.30 to 28.73 +/- 3.31 mumole . L(-1). In P3, N1, N2, N3, increases in plasma inorganic fluoride concentrations were significant (P < .05) and reached a peak value at Po1. The mean urine inorganic fluoride concentrations were 12.49 +/- 2.04 to 256.7 +/- 49.62 mumole . L(-1). In A2, A3, N1, N2, and N3, mean urine inorganic fluoride concentrations were significantly increased (P < .05) and the peak value was observed at Po1. Mean NAG concentrations in urine varied (5.6 +/- 1.6 IU . L(-1) to 12.5 +/- 1.14 IU . L(-1)) and peak level was observed at 30 minutes of the anhepatic phase (A2), which did not exceed the normal values for urine NAG levels (1.5 to 6.1 U . L(-1)). No impairment was observed in serum BUN and creatinine levels at any time. While there was only a slight increase in NAG during anhepatic phase, there was no change in plasma F1.

CONCLUSIONS

Sevoflurane seemed to have minimal effect on kidney functions of BUN and Cr levels during liver transplantation. Although urine F1 and NAG levels increased during the anhepatic phase plasma F1, BUN, and Cr levels did not, suggesting that renal F1 production may occur in the absence of hepatic function. The renal effect of sevoflurane in chronic liver disease is controversial and must be investigated in further studies.

Effects of cigarette smoking on serum fluoride concentrations and renal function integrity after 1 MAC-h sevoflurane anaesthesia

BACKGROUND

Tobacco smoke contains various chemicals which may affect drug metabolism. Sevoflurane is metabolized to inorganic fluoride, and elevated serum fluoride concentrations (S-F(-)) may cause deterioration of renal function. Whether smokers develop high S-F(-) and associated disturbances in renal function is not known.

METHODS

We investigated sevoflurane metabolism in 25 non-smoking and 25 smoking (> 10 cigarettes/day) generally healthy women, aged 19-68 years, undergoing gynaecological elective surgery under one minimum alveolar concentration-hour (1 MAC-h) standardized sevoflurane anaesthesia. S-F(-) was measured for 24 h. Glomerular and tubular function was assessed by measuring serum and urine tumour-associated trypsin inhibitor (TATI), beta(2)-microglobulin and serum creatinine for 48 h after sevoflurane inhalation.

RESULTS

There were no differences between the two study groups with regard to S-F(-). It increased significantly in both groups: in non-smokers, from a baseline between 1.0 and 11 micromol/l (median, 1.6 micromol/l) to a maximum between 8.2 and 40 micromol/l (26 micromol/l) (P < 0.001) and, in smokers, from a baseline between 0.5 and 5.2 micromol/l (1.7 micromol/l) to a maximum between 19 and 71 micromol/l (25 micromol/l) (P < 0.001). In both groups, S-F(-) remained elevated for the entire sampling period (P < 0.001). In all five women (one non-smoker and four smokers) with a maximum S-F(-) of 40 micromol/l or higher and an area under the serum fluoride concentration-time curve (AUC(F0-24)) of 500 micromol/h/l or higher, serum TATI increased above the pathological concentration of 3.0 nmol/l, whereas only six of the 45 patients with S-F(-) below 40 micromol/l had serum TATI above 3.0 nmol/l (P < 0.001). Beta(2)-Microglobulin increased significantly (> 1 mg/l) in two patients with high S-F(-) relative to two of the 45 patients with S-F(-) below 40 micromol/l (P= 0.005). None of the patients developed clinically detectable renal dysfunction.

CONCLUSION

Smoking did not affect S-F(-) after sevoflurane anaesthesia. Glomerular dysfunction, seen as increased serum TATI, was noted in five women with S-F(-) above 40 micromol/l. Our results suggest that the renal toxic threshold of S-F(-) seems to be lower than the earlier reported value of 50 micromol/l.

Rhabdomyolysis following laparoscopic radical nephrectomy: A case to heighten awareness

Rhabdomyolysis, myoglobinuria and acute renal failure are rare complication of surgery. Long operative time, increased body mass, lateral decubitus positioning and extracellular volume depletion may predispose to this condition. The authors describe the case of a 70-year-old man with renal cell carcinoma who underwent a laparoscopic right radical nephrectomy in the lateral decubitus position. His postoperative course was complicated by acute renal failure due to rhabdomyolysis. Heightened awareness, early recognition and treatment of this condition are important, particularly as laparoscopic nephrectomy is becoming a common procedure for living donor transplantation.

Extrahepatic Metabolism and Renal Effects of Sevoflurane in a Case of Liver Transplantation

In a case of liver transplantation, sevoflurane metabolism was studied to investigate if sevoflurane has an extrahepatic metabolism or possible nephrotoxicity in the presence of chronic liver disease. Plasma blood urea nitrogen (BUN) and creatinine and urine levels of N-acetyl glycosaminidase (NAG) and beta2 microglobulin were assessed intraoperatively and for 11 days postoperatively. We observed a close relation between urine NAG excretion and urine inorganic fluoride levels in the intraoperative period and early postoperative days. The NAG levels were greater than normal despite the peak serum inorganic fluoride concentration of 18.94 micromol/L. No impairment was observed in serum BUN or creatinine levels in these periods.

Alterations in the biochemical markers of renal function after sevoflurane anaesthesia

AIM

This study has been carried out to see whether renal function is acutely altered in patients undergoing sevoflurane anaesthesia. For this purpose, the urinary levels of markers of renal tubular function, namely leucine amino peptidase (LAP), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH) and beta-2 microglobulin (beta-2M), and urinary albumin as a predictor of renal glomerular function were measured before and after sevoflurane anaesthesia.

METHODS

This study was comprised of 20 patients (11 males and nine females) aged 18-55, who underwent various elective surgical procedures under general anaesthesia. Urine samples of all patients were collected before and 1, 2 and 8 h after the anaesthesia. The levels of LAP, GGT, beta-2M, and albumin were then expressed as factored by urinary creatinine. In all patients, the anaesthesia was maintained with sevoflurane (2% end-tidal) at a high flow-rate (6 L/min).

RESULTS

Urinary beta-2M and LAP levels after anaesthesia were unchanged (P > 0.05). While urinary GGT and ALP levels were found elevated in the first hour, LDH levels were higher in the second hour (P < 0.05). They returned to normal levels in the later periods after the anaesthesia. Urinary albumin excretion (UAE) was significantly elevated in the second hour after the anaesthesia (P < 0.001). Although UAE was decreased in the eighth hour after the anaesthesia, it still remained higher than the pre-anaesthesia level (P < 0.001).

CONCLUSIONS

These results suggest that a 2% end-tidal concentration of sevoflurane at a high flow-rate (6 L/min) acutely alters renal glomerular function but does not have a significant acute effect on biochemical markers of renal tubular damage.

Inhalation Anesthesiology and Volatile Liquid Anesthetics: Focus on Isoflurane, Desflurane, and Sevoflurane

Clinical pharmacists rarely are involved in the selection and dosing of anesthetic agents. However, when practicing evidence-based medicine in a cost-conscious health care system, optimizing drug therapy is imperative in all areas. Thus, we provide general information on anesthesiology, including the different types of breathing systems and the components of anesthesia machines. Modern inhalation anesthetics that are predominantly used in clinical practice include one gas--nitrous oxide--and new volatile liquid agents--isoflurane, desflurane, and sevoflurane. Desflurane and sevoflurane are the low-soluble inhalation anesthetics, and they offer some clinical advantages over isoflurane, such as fast induction and faster recovery with long procedures. However, efficient use of isoflurane can match the speed of induction and recovery of the other agents in certain cases. In addition, the patient characteristics, duration and type of procedure, type of breathing system, and efficiency in monitoring must be considered when selecting the most optimal therapy for each patient. Maximizing the clinical advantages of these agents while minimizing the waste of an institution's operating room and pharmacy budget requires an understanding of the characteristics, pharmacokinetics, and pharmacodynamics of these anesthetic agents and the collaborated effort from both the anesthesia and pharmacy departments. An anesthetic agent algorithm is provided as a sample decision-process tree for selecting among isoflurane, desflurane, and sevoflurane.

Renal effects of hypotensive anaesthesia in combination with acute normovolaemic haemodilution with hydroxyethyl starch 130/0.4 or isotonic saline

BACKGROUND

Hypotensive anaesthesia (HA) and acute normovolaemic haemodilution (ANH) are used separately to decrease per-operative blood loss. Reducing blood viscosity by adding ANH to HA may appear profitable in a situation with lowered perfusion pressure and concern about organ ischemia. The aim of this study was to clarify the influence of HA in combination with ANH using crystalloid or colloid as replacement fluid on renal function.

METHODS

Hypotensive anaesthesia was induced in 11 patients referred to major spine surgery using sevoflurane in combination with fentanyl/remifentanil. Acute normovolaemic haemodilution was carried out by drawing venous blood into standard blood bags and replacing it by isotonic saline 0.9% (Group S) or HES 130/0.4 (Group V). Renal function was evaluated before, during and up to 8 h after hypotension as the glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) by means of 51Cr-EDTA and 125I-Hippuran clearances.

RESULTS

Lowering mean arterial blood pressure decreased GFR and ERPF in both groups. During hypotension ERPF was lower in Group S (n = 5) than Group V (n = 6). Renal function was normalized postoperatively. We found a positive but non-significant correlation between the relative GFR change and the duration of hypotension.

CONCLUSION

In conclusion, our study demonstrated that renal function, assessed by GFR and ERPF, is transiently reduced during the combination of hypotensive anaesthesia and acute normovolaemic haemodilution. A colloid-based fluid regime (HES 130/0.4) used for haemodilution may preserve renal function to a greater extent than a crystalloid-based regime (0.9% saline).

Urinary sevoflurane and hexafluoro-isopropanol as biomarkers of low-level occupational exposure to sevoflurane

OBJECTIVES

Sevoflurane is an inhalation halogenated anaesthetic widely used in day and paediatric surgery. We were interested in evaluating biological markers of exposure to sevoflurane, which should improve the health surveillance of occupationally exposed personnel.

METHODS

A group of 36 subjects (13 male, 23 female) occupationally exposed to volatile anaesthetics in paediatric operating rooms was studied in a 2-week survey. Post-shift urine samples and specimens from passive samplers (for personal monitoring) were collected after 1.75-6 h morning exposure and analysed by headspace gas chromatography-mass spectrometry (GC-MS). Multiple determinations were assumed as independent values (in total, n = 78: 24 from men, 54 from women; 25 from smokers, 53 from non-smokers).

RESULTS

Median sevoflurane external values were 0.13 parts per million (ppm) (range 0.03-18.82) (n = 78), urinary sevoflurane 0.6 microg/l urine (ND-18.5)(n = 76) and total urinary hexafluoro-isopropanol (HFIP) 0.49 mg/l urine (ND-6833.4) (n = 75). A lower limit of detection (LOD) was achieved for urinary sevoflurane (0.03 microg/l urine), allowing quantitation of all but one of the samples; >25% of urine samples were unquantifiable by HFIP and were assigned a value equal to half the LOD of 0.10 mg/l(urine). Urinary sevoflurane correlated well with breathing-zone data (r2 = 0.697 at log-log linear regression), whereas total urinary HFIP (r2 = 0.562 at log-log linear regression) seemed to be better described by a three-parameter logistic function and appeared to be influenced by smoking habits. Biological indices corresponding to National Institute for Occupational Safety and Health (NIOSH) exposure limits, calculated as means of linear regression slope and y intercept, were 3.9 mug/l(urine) and 1.4 microg/l urine for sevoflurane (corresponding to 2 ppm and 0.5 ppm, respectively), and 2.66 mg/l urine and 0.82 mg/l urine for HFIP.

CONCLUSIONS

On the basis of our data, urinary unmodified, sevoflurane seems to be a more sensitive and reliable biomarker of short-term exposure to sevoflurane with respect to total urinary metabolite HFIP, which appears to be influenced by physiological and/or genetic individual traits, and seems to provide an estimate of integrated exposure.

Endovascular vs open AAA repair: similar effects on renal proximal tubular function

AIM

To compare the effect of open and endovascular repair on renal function.

MATERIALS AND METHODS

In a prospective, non-randomized study twenty-four abdominal aortic aneurysms (AAA) treatable with either method were repaired, 15 using endovascular device (ENDO group) and nine with open surgery with infrarenal aortic cross-clamping (OPEN group). All the patients had standardised general anaesthesia, intravascular fluid therapy and monitoring. Renal function tests and cardiovascular measurements were performed at predetermined intervals.

RESULTS

N-acetyl-beta-D-glucosaminidase indexed to urinary creatinine (U-NAG/crea), a sensitive marker of renal proximal tubular damage, increased similarly in both groups at the end of surgery (two-way ANOVA, p < 0.05). No patient developed clinical renal impairment, on the contrary, creatinine clearance was increased, serum cystatin C (a sensitive marker of renal glomerular filtration) and serum creatinine concentration decreased at 24 hours postoperatively (Wilcoxon paired test, p < 0.05). Intraoperative blood loss and the amount of administered crystalloids were higher in the OPEN than in the ENDO group (Mann-Whitney U-test, p < 0.05). The cardiovascular measurements were comparable between the groups. The mean (SD) amount of radio-contrast media given was 3.1 (1.1) ml/kg in the ENDO group.

CONCLUSIONS

Our results indicate that endovascular AAA repair does not protect renal proximal tubular function. A temporary renal tubular dysfunction was found both in open and in endovascular AAA repair which did not lead to permanent changes in renal function.

Fluoride metabolism in smokers and non-smokers following enflurane anaesthesia

BACKGROUND

Inorganic fluoride is released by the metabolism of enflurane and the increased serum fluoride concentrations may impair renal function. Tobacco smoke consists of numerous reactive compounds that can either induce or inhibit drug metabolism. Studies on the interaction of smoking with anaesthetic drug metabolism and possible toxicity are warranted.

METHODS

Sixteen non-smoking and 17 smoking (>10 cigarettes day(-1)) generally healthy women undergoing elective gynaecological surgery were given 1 MAC (minimum alveolar concentration)-hour standardized anaesthesia with enflurane in oxygen-air mixture. The serum inorganic fluoride and renal function markers beta(2)-microglobulin, tumour-associated trypsin inhibitor (TATI) and serum creatinine were measured for 48 h.

RESULTS

The greatest inorganic fluoride concentration was between 8.4 and 21.0 (mean 13.8 (SD 3.4)) micromol litre(-1) in the non-smokers and between 8.6 and 38.0 (18.7 (7.0)) micromol litre(-1) in the smokers; the mean difference was 4.9 micromol litre(-1) (95% confidence interval (CI) 1.0-8.8, P<0.05). Serum beta(2)-microglobulin, TATI and creatinine were not increased. Serum inorganic fluoride concentrations were significantly greater in the smokers compared with the non- smokers 1, 2, 3 and 6 h after 1 MAC-hour inhalation with enflurane (P<0.05). Inorganic fluoride concentrations were still increased 24 h after anaesthesia in both groups. Urine beta(2)-microglobulin and TATI creatinine ratio remained at low values during the whole 48-h period in both groups.

CONCLUSIONS

Regular smoking is associated with an increase in serum inorganic fluoride concentration after anaesthesia with enflurane, but there are no signs of renal damage.

Biological indices of kidney involvement in personnel exposed to sevoflurane in surgical areas

BACKGROUND

Fluoride, a main metabolite, and one degradation product of sevoflurane (SEV), called Compound A, are known to cause kidney effects in experimental animals. Other than in volunteers and patients, no research is available on exposed workers. The possible effects on the kidney in workers exposed in surgical areas were studied.

METHODS

Subjects exposed to SEV and nitrous oxide (N(2)O) in surgical areas (N = 61) using open (N = 25) or semi-closed (N = 36) circuits were submitted to biological monitoring. The same biological indices were determined in 43 controls also. Sevoflurane (SEVU), nitrous oxide (N(2)OU), total urinary proteins (TUP), N-acetyl-beta-D-glucosaminidase (NAGU), and glutamine synthetase (GSU) were measured in urine.

RESULTS

The mean values of environmental exposure were 31.3 ppm (range 0.9-111.6 ppm) for N(2)O and 0.28 ppm (range 0-1.88 ppm) for SEV. Exposed subjects had significantly higher excretion of TUP; a higher, not significant, excretion of GSU was also observed in subjects using open circuits. A significant correlation was found in all exposed subjects between NAGU and SEVU (r = 0.303, P < 0.05), GSU and N(2)OU (r = 0.382, P < 0.01) and, especially, GSU and SEVU (r = 0.650, P < 0.001). These correlations appeared to be influenced by the use of open circuits; infact, NAGU was well correlated to N(2)OU (r = 0.770, P < 0.001) and SEVU (r = 0.863, P < 0.001); GSU to N(2)OU (r = 0.468, P < 0.05) and SEVU (r = 0.735, P < 0.001).

CONCLUSIONS

Results show that no relevant effect on the kidney is present for the levels of exposure studied. Nevertheless, correlation between dose and response urinary indices supports that SEV, other than N(2)O, may influence kidney function, especially when open circuits are used.

Halogenated inhalational anaesthetics

The halogenated inhalational anaesthetics halothane, enflurane, isoflurane and desflurane can produce metabolic hepatocellular injury in humans to a variable extent. During metabolism of these anaesthetics, tissue acetylation occurs due to the formation of reactive intermediates. Proteins modified by acetylation may constitute neo-antigens with a potential for triggering an antibody-mediated immune response. The likelihood of suffering post-operative immune hepatitis depends on the amount of the anaesthetic metabolized and is thereby considerably less with enflurane, isoflurane or desflurane compared with halothane. Plasma inorganic fluoride concentrations are regularly increased after sevoflurane. Elevated inorganic fluoride concentrations have been associated with nephrotoxicity following methoxyflurane anaesthesia but not after sevoflurane. Another source of concern is the products of degradation from reactions with carbon dioxide absorbents. Most important is compound A, which has been shown to exhibit nephrotoxicity in rodents. However, no significant changes in renal function parameters have been reported in surgical patients.

Inhibition of human renal acid phosphatases by nephrotoxic micromolar concentrations of fluoride

Fluoride is considered to be a nephrotoxic substance, due to the association of 50-180 microM serum concentrations of fluoride with dose-related, subclinical to overt clinical renal impairment. At these concentrations the cellular targets of fluoride in renal tissue remain unknown. Fluoride at micromolar concentrations inhibits some enzymes including phosphatases. Here the effects of fluoride on a recently characterized acid phosphatase complex present only in a few human tissues were studied. This enzyme complex consists of alkaline fixation-resistant beta-glycerophosphatase and tartrate-resistant a-naphthyl phosphatase, and these are different from activities of known types of acid phosphatase and specific phosphatases. In kidney, strong activities for this complex are detected only in the endothelium of the afferent arterioles and in glomeruli. It appeared that alkaline fixation-resistant and lysosomal acid phosphatase activities were significantly inhibited in afferent arterioles and glomeruli by 75 microM fluoride. Tartrate-resistant activity was significantly inhibited by greater concentrations (250 microM). Inhibition of acid phosphatases in the afferent arterioles and glomeruli may be one renal target of fluoride nephrotoxicity. Although the physiological substrates of this acid phosphatase complex are unknown, its specific and restricted location may indicate a role in regulation of renal circulation.

Serum fluoride concentrations, biochemical and histopathological changes associated with prolonged sevoflurane anaesthesia in horses

The volatile anaesthetic sevoflurane is degraded to fluoride (F-) and a vinyl ether (Compound A), which have the potential to harm kidney and liver. Whether renal and hepatic injuries can occur in horses is unknown. Cardiopulmonary, biochemical and histopathological changes were studied in six healthy thoroughbred horses undergoing 18 h of low-flow sevoflurane anaesthesia. Serum F- concentrations were measured and clinical laboratory tests performed to assess hepatic and renal function before and during anaesthesia. Necropsy specimens of kidney and liver were harvested for microscopic examination and compared to pre-experimental needle biopsies. Cardiopulmonary parameters were maintained at clinically acceptable levels throughout anaesthesia. Immediately after initiation of sevoflurane inhalation, serum F- levels began to rise, reaching an ongoing 38-45 micromol 1(-1) plateau at 8 h of anaesthesia. Serum biochemical analysis revealed only mild increases in glucose and creatinine kinase and a decrease in total calcium. Beyond 10 h of anaesthesia mild, time-related changes in urine included increased volume, glucosuria and enzymuria. Histological examination revealed mild microscopic changes in the kidney involving mainly the distal tubule, but no remarkable alterations in liver tissue. These results indicate that horses can be maintained in a systemically healthy state during unusually prolonged sevoflurane anaesthesia with minimal risk of hepatocellular damage from this anaesthetic. Furthermore, changes in renal function and morphology observed after sevoflurane inhalation are judged minimal and appear to be clinically irrelevant; they may be the result of anaesthetic duration, physiological stressors, sevoflurane (or its degradation products) or other unkown factors associated with these animals and study conditions.

Renal toxicity with sevoflurane: a storm in a teacup?

The inhaled anaesthetic sevoflurane is metabolised into two products that have the potential to produce renal injury. Fluoride ions are produced by oxidative defluorination of sevoflurane by the cytochrome P450 system in the liver. Until recently, inorganic fluoride has been thought to be the aetiological agent responsible for fluorinated anaesthetic nephrotoxicity, with a toxic concentration threshold of 50 micromol/L in serum. However, studies of sevoflurane administration in animals and humans have not shown evidence of fluoride-induced nephrotoxicity, despite serum fluoride concentrations in this range. Compound A (fluoromethyl-2,2-difluoro-1-[trifluoromethyl] vinyl ether) is a breakdown product of sevoflurane produced by its interaction with carbon dioxide absorbents in the anaesthesia machine. The patient then inhales compound A. Compound A produces evidence of transient renal injury in rats. The mechanism of compound A renal toxicity is controversial, with the debate focused on the role of the renal cysteine conjugate beta-lyase pathway in the biotransformation of compound A. The significance of this debate centres on the fact that the beta-lyase pathway is 10- to 30-fold less active in humans than in rats. Therefore, if biotransformation by this pathway is responsible for the production of nephrotoxic metabolites of compound A, humans may be less susceptible to compound A renal toxicity than are rats. In three studies in human volunteers and one in surgical patients, prolonged (8-hour) sevoflurane exposures and low fresh gas flow rates resulted in significant exposures to compound A. Transient abnormalities were found in biochemical markers of renal injury measured in urine. These studies suggested that sevoflurane can result in renal toxicity, mediated by compound A, under specific circumstances. However, other studies using prolonged sevoflurane administration at low flow rates did not find evidence of renal injury. Finally, there are substantial data to document the safety of sevoflurane administered for shorter durations or at higher fresh gas flow rates. Therefore, the United States Food and Drug Administration recommends the use of sevoflurane with fresh gas flow rates at least 1 L/min for exposures up to 1 hour and at least 2 L/min for exposures greater than 1 hour. We believe this is a rational, cautious approach based on available data. However, it is important to note that other countries have not recommended such limitations on the clinical use of sevoflurane and problems have not been noted.

Ketorolac is not nephrotoxic in connection with sevoflurane anesthesia in patients undergoing breast surgery

Ketorolac, which may cause renal vasoconstriction by cyclooxygenase inhibition, is often administered to patients anesthetized with sevoflurane that is metabolized to inorganic fluoride (F(-)), another potential nephrotoxin. We assessed this possible interaction using urine N-acetyl-beta-D-glucosaminidase indexed to urinary creatinine (U-NAG/crea) as a marker of proximal tubular, beta2-microglobulin as a tubular, urine oxygen tension (P(u)O(2)) as a medullary, and erythropoietin as a marker of tubulointerstitial damage. Thirty women (ASA physical status I-II) undergoing breast surgery were included in our double-blinded study. They were allocated into two groups receiving either ketorolac 30 mg IM (Group K) or saline (Group C) at the time of premedication, at the end of, and 6 h after anesthesia maintained with sevoflurane. Urine output, U-NAG/crea, P(u)O(2,) serum creatinine, urea, and F(-) were assessed. Blood loss was larger in Group K (465 +/- 286 mL vs 240 +/- 149 mL, mean +/- SD, P < 0.05). The MAC-doses of sevoflurane were similar. U-NAG/crea increased during the first 2 h of anesthesia and serum F(-) peaked 2 h after the anesthesia without differences between the groups. There were no statistically significant changes in P(u)O(2), erythropoietin, beta2-microglobulin, serum creatinine, urea, or urine output during anesthesia or the recovery period in either group. Our results indicate that the kidneys are not affected by ketorolac administered in connection with sevoflurane anesthesia.

IMPLICATIONS

The different kinetics of N-acetyl-beta-D-glucosaminidase indexed to urinary creatinine and serum inorganic fluoride during and after sevoflurane anesthesia suggest that the observed mild renal tubular function deterioration is not caused by inorganic fluoride. Administration of ketorolac IM is therefore considered safe in adequately hydrated healthy adult patients given sevoflurane anesthesia.

The effects of low-flow sevoflurane and isoflurane anesthesia on renal function in patients with stable moderate renal insufficiency

Sevoflurane degrades to Compound A, which is nephrotoxic in rats. Therefore, the renal effects of Compound A is an area of intense debate. We investigated the effects of low-flow sevoflurane and isoflurane anesthesia on renal function in patients with stable renal insufficiency. Seventeen patients with a serum creatinine level of more than 1.5 mg/dL were anesthetized with sevoflurane or isoflurane at a total flow of 1 L/min. Serum creatinine and blood urea nitrogen were measured before anesthesia and again 1, 2, 3, 5, 7, and 14 days after anesthesia. The 24-h creatinine clearance was measured before anesthesia and 7 days after anesthesia. There were no significant differences in the blood urea nitrogen levels, serum creatinine concentrations, or creatinine clearance before and after anesthesia within each group. These results suggest that sevoflurane and isoflurane have similar effects on renal function in patients with moderately impaired renal function. Further study of the effects of low-flow sevoflurane anesthesia on impaired renal function with a larger sample size than ours is required to resolve the issue of sevoflurane safety in patients with renal insufficiency.

IMPLICATIONS

The serum creatinine and blood urea nitrogen data indicate that, for exposures of <130 ppm/h in Compound A inspired area under the curve, renal effects of low-flow sevoflurane are similar to those of isoflurane in patients with stable renal insufficiency.

Effect of intra-aortic magnesium on renal function during and after abdominal aortic surgery: a pilot study

BACKGROUND

Infrarenal aortic cross-clamping causes renal vasoconstriction. Magnesium may protect against renal deterioration through its vasodilatory properties.

METHODS

Thirty patients with normal preoperative renal function undergoing infrarenal aortic cross-clamping for elective aortic surgery received magnesium (4 mmol) or saline into the aorta immediately after aortic cross-clamping and again just before unclamping in a double-blind fashion. Pulmonary artery occlusion pressure was maintained 215 mmHg. Five patients with magnesium were excluded due to need for intravenous nitroglycerine because of myocardial ischaemia during the study.

RESULTS

Postoperative creatinine clearance remained unchanged in both groups. Urinary N-acetyl-beta-D-glucosaminidase excretion increased before and decreased after aortic cross-clamping in both groups. The concentrations of glutathione peroxidase in serum were identical between the two groups.

CONCLUSIONS

These data indicate that intra-aortic magnesium had no effect on renal function during or after aortic cross-clamping.

Sevoflurane and anesthesia for neurosurgery: a review

This review assesses the extent to which sevoflurane fulfills the requirements of the ideal inhalational agent for use in neuroanesthetic practice. Sevoflurane's pharmacokinetic profile is outlined. Data from animal and human studies are used to discuss its effects on cerebral hemodynamics, central nervous system monitoring, and cardiovascular parameters. Where possible, sevoflurane is compared with isoflurane, currently considered the inhalational agent of choice in neuroanesthesia. Sevoflurane's potential for toxicity is reviewed.

Pulmonary injury after ski wax inhalation exposure

A wide variety of irritants can lead to respiratory failure after inhalation injuries. We present a case of adult respiratory distress syndrome after exposure to a fluorocarbon resin (PFF 1020) used as ski wax. The patient sustained a mild but prolonged exposure to this substance, which subsequently led to symptoms of severe respiratory failure over the next 24 hours. Except for hypocalcemia, there were no systemic manifestations and recovery was uneventful. Ski wax is considered to be nontoxic and there are no reported side effects of these products. Injury was related to the heated fluorocarbon particles. This case report of a severe lung inhalation injury points out the increasing risk of environmental hazards associated with the use of synthetic substances.

Renal function in patients during and after hypotensive anesthesia with sevoflurane

STUDY OBJECTIVES

To evaluate renal function during and after hypotensive anesthesia with sevoflurane compared with isoflurane in the clinical setting.

DESIGN

Randomized, prospective study.

SETTING

Inpatient surgery at Rosai Hospital.

PATIENTS

26 ASA physical status I and II patients scheduled for orthopedic surgery.

INTERVENTIONS

Patients received isoflurane, nitrous oxide (N2O), and fentanyl (Group I = isoflurane group; n = 13) or sevoflurane, N2O, and fentanyl (Group S = sevoflurane group; n = 13). Controlled hypotension was induced with either isoflurane or sevoflurane to maintain mean arterial pressure at 60 mmHg for 120 minutes.

MEASUREMENTS AND MAIN RESULTS

Measurements included serum inorganic fluoride (previously speculated to influence renal function), creatinine clearance (CCr; to assess renal glomerular function), urinary N-acetyl-beta-D-glucosaminidase (NAG; to assess renal tubular function), blood urea nitrogen (BUN), and serum creatinine (as clinical renal function indices). Serum fluoride, CCr, and NAG were measured before hypotension, 60 minutes, and 120 minutes after the start of hypotension, 30 minutes after recovery of normotension, and on the first postoperative day. BUN and serum creatinine were measured preoperatively and on the third and seventh postoperative days. Minimum alveolar concentration times hour was 3.6 +/- 1.8 in Group I and 4.0 +/- 0.7 in Group S. In both groups, BUN and serum creatinine did not change, and CCr significantly decreased after the start of hypotension. In Group I, serum fluoride and NAG did not change. In Group S, serum fluoride significantly increased after the start of hypotension compared with prehypotension values and compared with Group I values. In addition, NAG significantly increased at 120 minutes after the start of hypotension and at 30 minutes after recovery of normotension, but returned to prehypotension values on the first postoperative day.

CONCLUSIONS

Two hours of hypotensive anesthesia with sevoflurane under 5 L/min total gas flow in patients having no preoperative renal dysfunction transiently increased NAG, which is consistent with a temporary, reversible disturbance of renal tubular function.

Cytochrome P450 2E1 activity in diabetic and obese patients as assessed by chlorzoxazone hydroxylation

Cytochrome P450 2E1 (CYP2E1) is a phase I detoxification enzyme, which is induced by chronic alcohol consumption. It is involved in the activation of numerous carcinogens and in the production of free radicals. As it has previously been shown to be induced in diabetic and obese rats, the aim of this study was to investigate its induction level in poorly-controlled diabetics and in obese patients (Body Mass Index > 30 kg/m2). CYP2E1 activity was determined in 35 diabetic and 17 obese patients by using the in vivo chlorzoxazone hydroxylation test. Even though the glucidic parameters were highly disturbed (mean fasting glycemia > 7.9 mmol/L, post prandial glycemia > 12.2 mmol/L and fructosamine > 326 mumol/L), CYP2E1 activity was not enhanced either in insulin-dependent diabetics (IDDs, n = 7) nor in non-obese non-insulin-dependent diabetics (NIDDs, n = 15) when compared to controls (n = 42) (0.21 +/- 0.03, 0.33 +/- 0.03 and 0.30 +/- 0.02, respectively, mean +/- SEM). However, this activity was lower in IDDs when compared to NIDDs (P < 0.05). In obese patients, with (n = 13) or without (n = 17) NIDD mellitus, CYP2E1 activity was increased by a mean of 40% when compared to controls. In addition, positive correlations were found in all subjects (controls or patients, n = 74) between CYP2E1 activity and serum cholesterol (r = 0.42, P < 0.0001), triglycerides (r = 0.44, P < 0.0001) and BMI (r = 0.36, P < 0.001). Accordingly, subjects with cholesterol and/or triglyceride serum levels above 6.4 and 1.8 mmol/L, respectively, displayed a mean increase of 40% of their CYP2E1 activity vs subjects within the above values. It is believed that individuals with increased CYP2E1 activity are more susceptible to the adverse effects of CYP2E1-mediated activation of toxins and carcinogens.

Dose-related biochemical markers of renal injury after sevoflurane versus desflurane anesthesia in volunteers

Sevoflurane (CH2F-O-CH[CF3]2) reacts with carbon dioxide absorbents to produce Compound A (CH2F-O-C[=CF2][CF3]). Because of concern about the potential nephrotoxicity of Compound A, the United States package label (but not that of several other countries) for sevoflurane recommends the use of fresh gas flow rates of 2 L/min or more. We previously demonstrated in humans that a 2-L/min flow rate delivery of 1.25 minimum alveolar anesthetic concentration (MAC) sevoflurane for 8 h can injure glomeruli (i.e., produce albuminuria) and proximal tubules (i.e., produce glucosuria and urinary excretion of alpha-glutathione-S-transferase [alpha-GST]). The present report extends this investigation to fasting volunteers given 4 h (n = 9) or 2 h (n = 7) of 1.25 MAC sevoflurane versus desflurane at 2 L/min via a standard circle absorber anesthetic system (all subjects given both anesthetics). Markers of renal injury (urinary creatinine, albumin, glucose, alpha-GST, and blood urea nitrogen) did not reveal significant injury after anesthesia with desflurane. Sevoflurane degradation with a 2-L/min fresh gas inflow rate produced average inspired concentrations of Compound A of 40 +/- 4 ppm (mean +/- SD, 8-h exposure [data from previous study]), 42 +/- 2 ppm (4 h), and 40 +/- 5 ppm (2 h). Relative to desflurane, sevoflurane given for 4 h caused statistically significant transient injury to glomeruli (slightly increased urinary albumin and serum creatinine) and to proximal tubules (increased urinary alpha-GST). Other measures of injury did not differ significantly between anesthetics. Neither anesthetic given for 2 h at 1.25 MAC produced injury. We conclude that 1.25 MAC sevoflurane plus Compound A produces dose-related glomerular and tubular injury with a threshold between 80 and 168 ppm/h of exposure to Compound A. This threshold for renal injury in normal humans approximates that found previously in normal rats.

IMPLICATIONS

Human (and rat) kidneys are injured by a reactive compound (Compound A) produced by degradation of the clinical inhaled anesthetic, sevoflurane. Injury increases with increasing duration of exposure to a given concentration of Compound A. The response to Compound A has several implications, as discussed in the article.

The relationship between cytochrome P4502E1 activity and plasma fluoride levels after sevoflurane anesthesia in humans

We determined whether the perianesthetic plasma fluoride levels after sevoflurane anesthesia in humans were correlated with the metabolic ratio (MR) of 6-hydroxychlorzoxazone to chlorzoxazone, an in vivo probe for cytochrome P4502E1 (CYP2E1) activity. Thirty ASA physical status I or II patients scheduled for extraabdominal surgery were randomized to a chlorzoxazone (n = 20) or a control group (n = 10). Patients in the chlorzoxazone group received 500 mg chlorzoxazone orally on the morning of the day of surgery. Chlorzoxazone and its 6-hydroxymetabolite concentrations were measured in plasma 2 h after drug administration. Anesthesia was induced with propofol, fentanyl, and atracurium intravenously and maintained with sevoflurane (inspired concentration 1-3 vol%). Plasma fluoride concentrations were determined before the induction of anesthesia, at the cessation of sevoflurane, and 2, 4, 6, 10, and 24 h thereafter. The area under the plasma fluoride concentration-time curve (AUC) was calculated up to 24 h after sevoflurane cessation. MR correlated significantly with the plasma fluoride AUC (r2 = 0.28, P < 0.025), the elimination constant calculated for the postanesthetic 10- to 24-h period (r2 = 0.30, P < 0.025), and the plasma fluoride levels 24 h after the cessation of sevoflurane (r2 = 0.48, P < 0.05). A comparison between groups indicated that the administration of chlorzoxazone itself did not alter the postanesthetic fluoride kinetics. Thus, the interindividual variability in perianesthetic plasma fluoride levels after sevoflurane anesthesia is reflected by differences in the MR of chlorzoxazone and hence is related to the interindividual variability in CYP2E1 activity. We conclude that although the predictive value is limited, this study provides a reasonable basis for examining renal function after sevoflurane anesthesia in a subgroup of patients with a high preoperative metabolic ratio of chlorzoxazone.

IMPLICATIONS

CYP2E1 metabolizes sevoflurane as measured by the metabolic ratio of chlorzoxazone. Patients with a high ratio may be used to justify examining renal function in patients receiving sevoflurane.

Splanchnic and renal deterioration during and after laparoscopic cholecystectomy: a comparison of the carbon dioxide pneumoperitoneum and the abdominal wall lift method

Carbon dioxide (CO2) pneumoperitoneum together with an increased intraabdominal pressure (IAP) induces a hemodynamic stress response, diminishes urine output, and may compromise splanchnic perfusion. A new retractor method may be less traumatic. Accordingly, 30 ASA physical status I or II patients undergoing laparoscopic cholecystectomy were randomly allocated to a CO2 pneumoperitoneum (IAP 12-13 mm Hg) (control) or to a gasless abdominal wall lift method (retractor) group. Anesthesia and intravascular fluids were standardized. Direct mean arterial pressure (MAP), urine output, urine-N-acetyl-beta-D-glucosaminidase (U-NAG), arterial blood gases, gastric mucosal PCO2, and intramucosal pH (pHi) were measured. Normoventilation was instituted in all patients. MAP increased (P < 0.001) only with CO2 pneumoperitoneum. Minute volume of ventilation had to be increased by 35% with CO2 insufflation. PaCO2 was significantly higher (P < 0.05) for 3 h postoperatively in the control group. Diuresis was less (P < 0.01) and U-NAG levels (P < 0.01) higher in the control group. The pHi decreased after induction of pneumoperitoneum up to three hours postoperatively and remained intact in the retractor group. We conclude that the retractor method for laparoscopic cholecystectomy ensures stable hemodynamics, prevents respiratory acidosis, and provides protection against biochemical effects, which reveal the renal and splanchic ischemia caused by CO2 insufflation.

IMPLICATIONS

A mechanical retractor method (gasless) was compared with conventional CO2 pneumoperitoneum for laparoscopic cholestectomy. The gasless method ensured stable hemodynamics, prevented respiratory acidosis, and provided protection against the renal and splanchnic ischemia seen with CO2 pneumoperitoneum.

Intracranial pressure, middle cerebral artery flow velocity, and plasma inorganic fluoride concentrations in neurosurgical patients receiving sevoflurane or isoflurane

This study examined the concentration-related effects of sevoflurane and isoflurane on cerebral physiology and plasma inorganic fluoride concentrations. Middle cerebral artery flow velocity (Vmca), intracranial pressure (ICP), electroencephalogram (EEG) activity, and jugular bulb venous oxygen saturation were measured, and cerebral perfusion pressure (CPP) and estimated cerebral vascular resistance (CVRe) were calculated at baseline and at 0.5, 1.0, and 1.5 minimum alveolar anesthetic concentration (MAC) sevoflurane (n = 8) or isoflurane (n = 6). Mannitol 0.5-0.75 g/kg was given before dural incision, and blood was sampled for plasma inorganic fluoride during surgery and for up to 72 h postoperatively. Both sevoflurane and isoflurane decreased Vmca (to 31 +/- 12 - 36 +/- 14 cm/s, mean +/- SD), did not significantly alter ICP (13 +/- 9 - 15 +/- 11 mm Hg), and did not cause epileptiform EEG activity. With sevoflurane, decreased Vmca was accompanied by decreased CPP and unchanged CVRe at 0.5 MAC, and unchanged CPP and increased CVRe at 1.0 and 1.5 MAC. Plasma inorganic fluoride was 39.0 +/- 12.9 microM at the end of anesthesia (3.2 +/- 2.0 MAC hours) with sevoflurane, similar to the value (36.2 +/- 3.9 microM) for 3.7 +/- 0.1 MAC hours sevoflurane in patients not receiving mannitol. Decreased Vmca during sevoflurane presumably results from decreased cerebral metabolic rate, with CVRe changing secondarily in accord with CPP. Plasma inorganic fluoride does not seem to be altered by mannitol-induced diuresis.

IMPLICATIONS

In neurosurgical patients, sevoflurane decreased middle cerebral artery flow velocity and caused no epileptiform electroencephalogram activity and no increase of intracranial pressure or plasma inorganic fluoride. These effects are suitable for neurosurgery. Two other possible effects of sevoflurane, i.e., increased cerebrospinal fluid volume and/or intracranial elastance, may not be suitable for neurosurgery and warrant further study.