Corrosion of Penlon sevoflurane vaporisers

A new perspective on metals and other contaminants in fluoridation chemicals

BACKGROUND

Fluoride additives contain metal contaminants that must be diluted to meet drinking water regulations. However, each raw additive batch supplied to water facilities does not come labeled with concentrations per contaminant. This omission distorts exposure profiles and the risks associated with accidents and routine use.

OBJECTIVES

This study provides an independent determination of the metal content of raw fluoride products.

METHODS

Metal concentrations were analyzed in three hydrofluorosilicic acid (HFS) and four sodium fluoride (NaF) samples using inductively coupled plasma-atomic emission spectrometry. Arsenic levels were confirmed using graphite furnace atomic absorption analysis.

RESULTS

Results show that metal content varies with batch, and all HFS samples contained arsenic (4·9-56·0 ppm) or arsenic in addition to lead (10·3 ppm). Two NaF samples contained barium (13·3-18·0 ppm) instead. All HFS (212-415 ppm) and NaF (3312-3630 ppm) additives contained a surprising amount of aluminum.

CONCLUSIONS

Such contaminant content creates a regulatory blind spot that jeopardizes any safe use of fluoride additives.

A double-blind comparative study between Generic Sevoflurane and Sevorane™

BACKGROUND AND OBJECTIVES

Sevoflurane is presented in three types of vials. The differences in physical-chemical properties of those products are due to different manufacturing processes, although they are essentially identical regarding chemical comparison tests. It has been hypothesized that the Sevoflurane molecule could present chemical instability due to the formation of Lewis acids as a consequence of the materials used in the fabrication of the vials and the water content. The objective of this study was to analyze the clinical efficacy of Sevoflurane conditioned in different vials.

METHODS

Sixty-four adult patients were randomly divided into two groups. Two Datex-Ohmeda vaporizers, one with only Generic Sevoflurane and the other with Sevorane™, were used. The study coordinator was responsible for supplying the vaporizers and he did not participated in none anesthetic procedures. The same anesthetic technique and monitoring (ECG, HR, SpO₂, P(ET)CO₂, BIS, SEF, TOF, % INSP, % EXP, SBP, and DBP) were used in both groups.

RESULTS

During anesthesia, differences were not observed between both groups. A statistically significant difference was observed in the time between the interruption of Sevoflurane and spontaneous eye opening (13,91 ± 6.39 min in Group II, and 10.34 ± 6.05 min in Group I) and the interruption of Sevoflurane and handgrip on verbal command (15.38 ± 6.47 min in Group II, and 11.88 ± 6.60 in Group I). A statistically significance difference was not observed between the interruption of Sevoflurane and the moment that patients achieved an Aldrete- Kroulik index equal or above 8.

CONCLUSIONS

during anesthesia a significant difference between both groups was not observed. Although awakening was 3,5 minutes faster in Group I (Generic Sevoflurane), anesthesiologists did not observe any difference in the clinical behavior of patients.

Sevoflurane formulation water content influences degradation by Lewis acids in vaporizers

BACKGROUND

Sevoflurane is produced by several manufacturers. Currently marketed sevoflurane formulations differ in their method of synthesis, impurities, containers in which they are sold, and water content. Of the various types of chemical degradation to which sevoflurane is susceptible, the most pertinent is degradation by Lewis acids (such as metal oxides and metal halides) to hydrofluoric acid and other toxic compounds. Water inhibits such degradation. This observational study determined the degradation profile of three formulations of sevoflurane (two lower-water and one higher-water formulation) when stored in three types of vaporizers.

METHODS

Lower-water sevoflurane (Eraldin, Laboratorios Richmond/Minrad, Argentina [19 ppm water] and generic sevoflurane, Baxter, US [57 ppm water]) and higher-water sevoflurane formulations (Ultane, Abbott, US [352 ppm water]) were stored in three different vaporizers (Draeger Vapor 2000, GE/Datex-Ohmeda Tec 7, Penlon Sigma Delta) under accelerated storage conditions (40 degrees C). Sevoflurane was sampled from each vaporizer immediately following filling and after 1, 2, and 3 wk, and analyzed for water content, pH, fluoride, and total degradants.

RESULTS

Lower-water sevoflurane formulations stored in the Penlon Sigma Delta vaporizers contained time dependent increases in hydrofluoric acid (pH decreased as low as 3, fluoride concentration as high as 600 ppm), and total degradants (>68,000 ppm). Penlon Sigma Delta vaporizers filled with lower-water sevoflurane formulations showed substantial etching of the sight glass and metal filler shoe after 3 wk of storage. The higher-water sevoflurane formulation (Ultane, Abbott, US [352 ppm water]) contained negligible amounts of fluoride or degradants, and small decreases in pH. Sevoflurane stored in Draeger Vapor 2000 and GE/Datex-Ohmeda Tec 7 showed negligible changes in pH, fluoride concentration, and degradants.

CONCLUSIONS

Lower-water sevoflurane underwent substantial degradation to hydrofluoric acid and other degradants during storage in the Penlon Sigma Delta vaporizer. Differences in water content of sevoflurane formulations and potential for degradation present a potential patient safety issue.