Biological monitoring during exposure to the anesthetics isoflurane and sevoflurane

Exposure to traces of inhaled anaesthetic agents may impair the health of the operating theatre personnel. Although no cause-effect relationship has been found, most public health authorities recommend various occupational exposure standards to minimize possible health risks. If metabolites of the substances are known, biological monitoring is an alternative to the monitoring of the operating theatre's air. The new anaesthetic agent Sevoflurane is considerably more transformed to fluoride than Isoflurane. Concerning fluoride there exist Biological Tolerance Values of 4.0-7.0 mg fluoride (F-) per gram creatinine (Crea). The aim of our study was to compare the fluoride excretion under the occupational exposure to sevoflurane and isoflurane. By the means of a direct-reading instrument trace concentrations of sevoflurane, isoflurane, and nitrous oxide were measured during 40 anaesthetic procedures. Urine samples were collected before (Z1) and after the workshift (Z2), and in the morning of the next day (Z3). The analysis was done by the means of an ionselective electrode. The personnel-related concentrations (median, range) were 0.50 (0.16-7.04) ppm isoflurance and 27.36 (5.87-467.10) ppm nitrous oxide, and 0.79 (0.15-1.95) ppm sevoflurane and 17.74 (2.45-84.20) ppm nitrous oxide. The resulting fluoride values presented at Z1, Z2, and Z3 as median (range) during exposure to isoflurane were 0.15 (0.11-0.53), 0.19 (0.11-0.53), 0.20 (0.11-0.31) mg F-/g Crea, and 0.15 (0.10-0.46), 0.22 (0.13-0.44), 0.23 (0.15-0.69) mg F-/g Crea during exposure to sevoflurance, respectively. The trace concentrations were clearly under 10 ppm for the volatile substances and 100 ppm for nitrous oxide. The values are comparable to data recorded under similar working conditions. The measured fluoride values were low and remained under the legal tolerance values. Under the described conditions potential health risks were low.     

Subjective, psychomotor, cognitive, and analgesic effects of subanesthetic concentrations of sevoflurane and nitrous oxide

BACKGROUND: Sevoflurane is a volatile general anesthetic that differs in chemical nature from the gaseous anesthetic nitrous oxide. In a controlled laboratory setting, the authors characterized the subjective, psychomotor, and analgesic effects of sevoflurane and nitrous oxide at two equal minimum alveolar subanesthetic concentrations. METHODS: A crossover design was used to test the effects of two end-tidal concentrations of sevoflurane (0.3% and 0.60%), two end-tidal concentrations of nitrous oxide (15% and 30%) that were equal in minimum alveolar concentration to that of sevoflurane, and placebo (100% oxygen) in 12 healthy volunteers. The volunteers inhaled one of these concentrations of sevoflurane, nitrous oxide, or placebo for 35 min. Dependent measures included subjective, psychomotor, and physiologic effects, and pain ratings measured during a cold-water test. RESULTS: Sevoflurane produced a greater degree of amnesia, psychomotor impairment, and drowsiness than did equal minimum alveolar concentrations of nitrous oxide. Recovery from sevoflurane and nitrous oxide effects was rapid. Nitrous oxide but not sevoflurane had analgesic effects. CONCLUSIONS: Sevoflurane and nitrous oxide produced different profiles of subjective, behavioral, and cognitive effects, with sevoflurane, in general, producing an overall greater magnitude of effect. The differences in effects between sevoflurane and nitrous oxide are consistent with the differences in their chemical nature and putative mechanisms of action.     

Single-breath inhalation induction of sevoflurane anaesthesia with and without nitrous oxide: a feasibility study in adults and comparison with an intravenous bolus of propofol

The induction characteristics of sevoflurane in nitrous oxide and oxygen were compared with sevoflurane in oxygen alone and a propofol infusion. A vital capacity technique was used for the gaseous induction groups using a Mapleson A system and a 4-litre reservoir bag. Four end-points of anaesthesia were recorded: time to cessation of finger tapping, time to loss of eyelash reflex, time to jaw relaxation and time to regular settled breathing after laryngeal mask airway insertion. We also recorded sequential blood pressure and pulse rate, the incidence of adverse airway events and the acceptability of the induction technique. Propofol had a faster time to cessation of finger tapping (p < 0.05) and jaw relaxation (p < 0.01). These differences disappeared with the final induction stage and sevoflurane in nitrous oxide and oxygen had the faster time to regular settled breathing, though this did not reach statistical significance. Cardiovascular stability was good and comparable in all groups. There were few adverse airway events in any group and none caused oxygen saturation to fall below 96%. There was more excitation in the gaseous induction groups, though this did not interfere with induction. Patient satisfaction with induction was high.     

Pollution of the work environment by volatile anesthetics and nitrous oxide]

Anaesthetic personnel is exposed to different workload conditions. The individual impact is influenced by external factors and human stress stability. Different symptoms reported to be present in anaesthetic personnel are comparable to symptoms of the sick building syndrome, defined by the WHO in the 90's. They are caused by work-induced distress and the exposure to chemical hazards. In anaesthesia, health defects by anaesthetic vapours and gases have been deplored for many years. After the Russian anaesthesiologist Vaisman published a report in 1967, controlled studies concerning cancerogenicity and teratogenicity of volatile anaesthetics under workspace conditions were carried out. In 1989, time-weighted average exposure threshold limit values of 5 ppm were released in the Federal Republic of Germany for halothane. In 1993 thresholds for enflurane (20 ppm) and nitrous oxide (100 ppm) were released. TLV concentrations for the new anaesthetic agents desflurane and sevoflurane have not yet been defined by authorities. Factors influencing workplace concentrations of anaesthetic gases are the anaesthetic procedures, apparatus leakage, air conditioning, fresh gas flow and the function of the scavenging system. Although cancerogenicity, mutagenicity, teratogenicity and reduction of fertility are discussed as effects of chronic exposure to anaesthetic gases, several review articles doubted the results of studies, finding positive correlations of incidence of occupational disease and the exposure to the volatile and gaseous substances. Mainly coexisting factors like smoke-induced exposure to polybromated biphenyls, disturbance in circadian rhythm, stress and enclosure in narrow exposure systems, increasing teratogenicity and cancerogenicity in animal experiments, are considered to promote unreliability of the studies. All reviewers do not discuss the fact, that all of these co-factors are present in the reality of the anaesthetic workplace. Thus, the studies by Corbett, enthusiastically criticized by different reviewers, simulate the all-day reality of the anaesthetic workplace more precisely than controlled experiments conducted, for example, by Eger and co-workers. The results of animal experiments and retrospective studies therefore do not justify realization of large controlled prospective studies but require the overall revision of the anaesthesiological workplace and the reduction of occupational waste gas exposure to the lowest possible levels below all chronic exposure threshold values.     

Induction of anesthesia and tracheal intubation with sevoflurane in adults

BACKGROUND: The speed, quality, and cost of mask induction of anesthesia and laryngeal mask airway insertion or tracheal intubation were studied in young non-premedicated volunteers given high inspired concentrations of sevoflurane (6 to 7%). METHODS: Twenty healthy persons who were 19 to 32 years old participated three times, received 6 l/min fresh gas flow, and were randomized to receive 6 to 7% sevoflurane in 66% nitrous oxide/28% oxygen by face mask until tracheal intubation (treatment 1) or until laryngeal mask airway insertion (treatment 3), or 6 to 7% sevoflurane without nitrous oxide to tracheal intubation (treatment 2). Participants exhaled to residual volume and took three vital capacity breaths of the gas mixture; thereafter ventilation was manually assisted. The time of exposure to the inhaled gas was varied for consecutive participants. It was either increased or decreased by 30-sec increments based on the failure or success of the preceding volunteer's response to laryngoscopy and intubation after a preselected exposure time. Failure was defined as poor jaw relaxation, coughing or bucking, or inadequate vocal cord relaxation. RESULTS: Loss of the lid-lash reflex in unpremedicated young volunteers was achieved in 1 min and did not differ among groups. Average time (and 95% confidence interval) for acceptable conditions for LMA insertion was achieved in 1.7 (0.7 to 2.7) min, and all participants had an immediate return of spontaneous ventilation. The time for acceptable tracheal intubating conditions after manual hyperventilation by mask was 4.7 (3.7 to 5.7) min and 6.4 (5.1 to 7.7) min in treatments 1 and 2, respectively. There were no cases of increased secretions or laryngospasm. The incidence of breath holding and expiratory stridor ("crowing") was 7.5% and 25%, respectively, during treatment 1 and 15% and 40%, respectively, during treatment 2. CONCLUSIONS: The induction of anesthesia to loss of lid reflex in young non-premedicated adults approaches the speed of intravenous induction techniques. No untoward airway responses were noted during mask induction of anesthesia with a three-breath technique. In response to intubation, no adverse airway responses, including jaw tightness, laryngospasm, and excessive coughing or bucking, occurred in participants whose duration of mask administration of sevoflurane met the appropriate times (as determined in this study).     

Single vital capacity inhalational anaesthetic induction in adults--isoflurane vs sevoflurane

PURPOSE: To evaluate whether isoflurane is as suitable as sevoflurane for the single vital capacity breath (VCB) method of inhalational induction in patients premedicated with midazolam. METHODS: A randomised, controlled, double-blind study involving 67 ASA I-II patients aged between 18-50 yr undergoing elective surgery under general anaesthesia. All participants received premedication with 0.03 mg.kg-1 midazolam i.v. Using a primed circle absorber circuit, inhalational induction of anaesthesia was performed with the single VCB method using either isoflurane 3.5% or sevoflurane 7.5% in nitrous oxide 67% in oxygen, representing approximately equivalent MAC-multiples of 3.6 MAC. Isoflurane was compared with sevoflurane in terms of rapidity, efficacy, safety and acceptability of induction. RESULTS: With the single VCB method, sevoflurane produced a faster (45 +/- 21 vs 71 +/- 22 sec, P < 0.01), more successful (100% vs 75.8%, P < 0.01) induction of anaesthesia, with fewer induction-related complications (11.8% vs 84.8%, P < 0.01) than did isoflurane. There was also greater patient acceptability of induction with sevoflurane (76.4% vs 42.4%, P < 0.05). CONCLUSION: In adults given midazolam premedication, isoflurane is not as suitable as sevoflurane for single VCB inhalational anaesthetic induction technique as it is associated with slower, more complicated induction and less patient acceptability.     

Occupational exposure to inhalation anesthetics at the work-place of veterinary surgery

In a prospective study we evaluated the work-place pollution by isoflurane and nitrous oxide during various anaesthetic procedures in animal surgery. The study was conducted during one working week at an University Animal Department. Trace concentrations of isoflurane and nitrous oxide were directly measured every minute in the breathing zone by means of a photoacoustic infrared spectrometer in two different operating rooms (OR) with an air turnover of 17 changes per hour. In one OR the 8-hour time-weighted average (mean +/- SEM) was calculated to be 12.3 +/- 9.9 ppm nitrous oxide and 1.9 +/- 2.5 ppm isoflurane. The other OR, where only isoflurane was used, was contaminated with 5.3 +/- 8.1 ppm isoflurane. In the first OR, the trace gas concentrations were low and comparable to values obtained under human anaesthesia in adults and children. The higher contamination in the second OR resulted from performing inhalational anaesthesia with an open mask system in birds and small animals. Although the mean values were below the recommended occupational exposure standards, some high peak values (> 300 ppm isoflurane) violated these threshold limits. We recommend the use of a local scavenging device, if other alternatives such as total intravenous anaesthesia are not possible.     

Increase in serum creatine phosphokinase concentrations after suxamethonium during sevoflurane or isoflurane anaesthesia in children

We have studied whether sevoflurane or isoflurane anaesthesia modulates the effect of suxamethonium on serum concentrations of enzyme markers of skeletal muscle function in paediatric patients. Eighty patients undergoing bilateral tonsillectomy, aged 5-12 yr, were allocated randomly to receive anaesthesia with either sevoflurane and nitrous oxide or isoflurane and nitrous oxide. Serum creatine phosphokinase (CK), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) concentrations were measured before, and at 30 min and 20 h after induction of anaesthesia. Mean CK concentrations increased from 97.0 (SD 17.3) to 478 (170) iu litre-1 in the sevoflurane group and from 86.9 (22.4) to 628 (223) iu litre-1 in the isoflurane group, 20 h after induction of anaesthesia. Mean peak serum CK concentration in the sevoflurane group (478 (170) iu litre-1) was significantly less (P < 0.05) than that in the isoflurane group (628 (223) iu litre-1). Mean serum AST concentration increased from 17.5 (4.9) to 31.7 (3.5) iu litre-1 in the sevoflurane group and from 17.3 (2.4) to 34.8 (5.7) iu litre-1 in the isoflurane group, 20 h after induction of anaesthesia. Mean peak serum AST concentrations in the sevoflurane group were significantly lower (P < 0.05) than those in the isoflurane group. There were no significant differences in serum ALT or LDH concentrations between the groups either before or after anaesthesia. We conclude that administration of suxamethonium during either sevoflurane or isoflurane anaesthesia caused a marked increase in serum CK concentrations in paediatric patients. The clinical significance of this finding is uncertain.     

JC virus detection in the cerebrospinal fluid of AIDS patients with progressive multifocal leucoencephalopathy and monitoring of the antiviral treatment by a PCR method

Data from two published and one new meta-analysis were reviewed to compare the antiemetic efficacy of three different anaesthetic regimens: (i) propofol anaesthesia compared with another anaesthetic (control); (ii) anaesthesia without nitrous oxide compared with the same anaesthetic with nitrous oxide (control); (iii) propofol anaesthesia without nitrous oxide (TIVA) compared with another anaesthetic with nitrous oxide (control). Efficacy (prevention of postoperative nausea and vomiting compared with control) was estimated using odds ratio and number-needed-to-treat methods, and compared within a range of 20-60% control event rates for early efficacy (0-6 h) and 40-80% for late efficacy (0-48 h). Propofol anaesthesia or omitting nitrous oxide had similar effects on vomiting, both early and late. Propofol (but not omitting nitrous oxide) decreased the incidence of nausea. TIVA studies were documented poorly; appropriate comparison with other interventions were not possible. Efficacy of treatments should be compared within a setting-specific range of control event rates. There is insufficient evidence that TIVA with propofol is an anaesthetic technique with a low emetogenic potency.     

Renal medullary carcinoma

Hyperhomocysteinemia is an independent risk factor for coronary artery and cerebrovascular disease, but its significance in the perioperative period is unknown. Nitrous oxide inhibits methionine synthase, which aids in the conversion of homocysteine to methionine. In this prospective, controlled, randomized study, we determined the effect of intraoperative nitrous oxide exposure on postoperative plasma homocysteine concentrations. Twenty ASA physical status I-III patients, aged >18 yr, presenting for elective craniotomy, were randomized to receive general anesthesia with or without nitrous oxide (inspired nitrous oxide >50%). Plasma was sampled before the induction of anesthesia, on arrival in the postanesthesia care unit (PACU) after discontinuation of nitrous oxide, and 24 h after induction. There was a significant increase (22.6+/-11.4 vs 13.0+/-4.7 micromol/L; P = 0.0038 for postoperative versus preinduction values) in plasma homocysteine concentrations in the nitrous oxide group on arrival in the PACU and for 24 h. In the nonnitrous oxide group, mean plasma homocysteine concentrations did not change (9.5+/-1.9 vs 9.8+/-1.6 micromol/L; P = 0.86 for postoperative versus preinduction values). The change in plasma homocysteine concentrations in the nitrous oxide group was significantly different from that in the nonnitrous group (P = 0.0031). We conclude that the use of intraoperative nitrous oxide leads to significant increases in perioperative plasma homocysteine concentrations. IMPLICATIONS: Short-term exposure to nitrous oxide led to significant increases in plasma homocysteine. Further investigations are required to determine the clinical significance of this change.     

Effects of xenon on hemodynamic responses to skin incision in humans

BACKGROUND: The authors evaluated the hemodynamic suppressive effects of xenon in combination with sevoflurane at skin incision in patients undergoing surgery. METHODS: Forty patients were assigned randomly to receive one of the following four anesthetics: 1.3 minimum alveolar concentration (MAC) sevoflurane, 0.7 MAC xenon with 0.6 MAC sevoflurane, 1 MAC xenon with 0.3 MAC sevoflurane, or 0.7 MAC nitrous oxide with 0.6 MAC sevoflurane (n = 10 each group). Systolic blood pressure and heart rate were measured before anesthesia, before incision, and approximately 1 min after incision. RESULTS: The changes in hemodynamic variables in response to incision were less with sevoflurane in combination with xenon and nitrous oxide than with sevoflurane alone. Changes in heart rate (in beats/min) were 19+/-11 (+/- SD) for sevoflurane alone, 11+/-6 for 0.7 MAC xenon-sevoflurane, 4+/-4 for 1 MAC xenon-sevoflurane, and 8+/-7 for nitrous oxide-sevoflurane. Changes in systolic blood pressure were 35+/-18 mmHg for sevoflurane alone, 18+/-8 mmHg for 0.7 MAC xenon-sevoflurane, 16+/-7 mmHg for 1 MAC xenon-sevoflurane, and 14+/-10 mmHg for nitrous oxide-sevoflurane. CONCLUSIONS: Xenon and nitrous oxide in combination with sevoflurane can reduce hemodynamic responses to skin incision compared with sevoflurane alone. One probable explanation may be that xenon has analgesic properties similar to those of nitrous oxide, although the exact mechanism is yet to be determined.     

Arthroscopy in the elderly

The uptake rate of oxygen and nitrous oxide were studied during low flow anaesthesia with enflurane or isoflurane in nitrous oxide with either spontaneous or controlled ventilation. The excess gas flow and composition were analysed. The nitrous oxide uptake rate was in agreement with Severinghaus' formula VN20 1000.t-0.5. The composition of excess gas was predictable and the following formula for oxygen uptake could be derived: VO2 = VfgO2-0.45 (VfgN2(0)-(kg: 70.1000.t-0.5)) where oxygen uptake rate (VO2, ml.min-1) equals oxygen fresh gas flow (VfgO2) minus 0.45 times the difference between the fresh gas flow of nitrous oxide (VfgN2O), ml.min-1 and estimated uptake of nitrous oxide. The equation assumes constant inspired gas concentrations of 30% oxygen and 65-70% nitrous oxide. The oxygen uptake rates calculated from this formula were in good agreement with measured uptake rates. Thus, continuous monitoring of oxygen uptake rates is possible by using only reliable flowmeters and analysis of inspired oxygen concentration.     

Clinical sevoflurane metabolism and disposition. I. Sevoflurane and metabolite pharmacokinetics

BACKGROUND: Sevoflurane has low blood and tissue solubility and is metabolized to free fluoride and hexafluoroisopropanol (HFIP). Although sevoflurane uptake and distribution and fluoride formation have been described, the pharmacokinetics of HFIP formation and elimination are incompletely understood. This investigation comprehensively characterized the simultaneous disposition of sevoflurane, fluoride, and HFIP. METHODS: Ten patients within 30% of ideal body weight who provided institutional review board-approved informed consent received sevoflurane (2.7% end-tidal, 1.3 MAC) in oxygen for 3 h after propofol induction, after which anesthesia was maintained with propofol, fentanyl, and nitrous oxide. Sevoflurane and unconjugated and total HFIP concentrations in blood were determined during anesthesia and for 8 h thereafter. Plasma and urine fluoride and total HFIP concentrations were measured during and through 96 h after anesthetic administration. Fluoride and HFIP were quantitated using an ion-selective electrode and by gas chromatography, respectively. RESULTS: The total sevoflurane dose, calculated from the pulmonary uptake rate, was 88.8 +/- 9.1 mmol. Sevoflurane was rapidly metabolized to the primary metabolites fluoride and HFIP, which were eliminated in urine. HFIP circulated in blood primarily as a glucuronide conjugate, with unconjugated HFIP < or = 15% of total HFIP concentrations. In blood, peak unconjugated HFIP concentrations were less than 1% of peak sevoflurane concentrations. Apparent renal fluoride and HFIP clearances (mean +/- SE) were 51.8 +/- 4.5 and 52.6 +/- 6.1 ml/min, and apparent elimination half-lives were 21.4 +/- 2.8 and 20.1 +/- 2.6 h, respectively. Renal HFIP and net fluoride excretion were 4,300 +/- 540 and 3,300 +/- 540 mumol. Compared with the estimated sevoflurane uptake, 4.9 +/- 0.5% of the dose taken up was eliminated in the urine as HFIP. For fluoride, 3.7 +/- 0.4% of the sevoflurane dose taken up was eliminated in the urine, which, because a portion of fluoride is sequestered in bone, corresponded to approximately 5.6% of the sevoflurane dose metabolized to fluoride. CONCLUSIONS: Sevoflurane was rapidly metabolized to fluoride and HFIP, which was rapidly glucuronidated and eliminated in the urine. The overall extent of sevoflurane metabolism was approximately 5%.     

Exposure of the pediatric surgeon to inhalation-anesthetic during pediatric bronchoscopy procedures

BACKGROUND: General anaesthetic agents are frequently used for paediatric bronchoscopy. A disadvantage of this open system anaesthesia seems to be the contamination of the working environment. The aim of this study was to determine the exposure of the endoscopist during paediatric bronchoscopy under general anaesthesia in different working environments and to compare these measurements with the currently valid international threshold limit values. MATERIAL AND METHODS: 25 children (ASA I-III) scheduled for diagnostic bronchoscopy were included in the study. After inhalational induction all children were intubated with a nonflexible bronchoscope and manually ventilated through a side arm of the bronchoscope. Maintenance of anaesthesia was achieved with sevoflurane (2-3 vol%) in 80% oxygen. Trace concentrations were measured every 90 seconds in the breathing zones of the paediatrician by means of a highly sensitive direct-reading instrument (Brüel & Kjaer 1302). The lower detection limit was 0.02 ppm. The investigation was done in an OT with and without air conditioning and scavening system. RESULTS: The mean age of the children was 50.3 months (range: 3-109 months). Ventilation and oxygenation were stable throughout the bronchoscopic procedure. Mean exposure of the paediatrician without air-conditioning and scavening system to sevoflurane was over 50 ppm for the endoscopist. All international threshold limit values were exceeded. Peak concentrations higher than 100 ppm sevoflurane were detected repeatedly in 40% of anaesthesias. During bronchoscopy in the operating room equipped with laminar air flow (20.2 air exchanges per hour) and narcotic gas evacuation (30 l/min) the mean exposure of the paediatrician was 26.4 ppm sevoflurane. CONCLUSIONS: The main finding of the present study is that under inhalation anaesthesia with sevoflurane for paediatric bronchoscopy occupation exposure is higher than the limits stated in all known health regulation guidelines. Therefore, in case of such working conditions, the use of total intravenous anaesthesia is advocated also in very small infants.     

Anesthesia in a patient with epidermolysis bullosa

A 6-year-old-boy with epidermolysis bullosa underwent plastic surgeries for the scar contraction of hands. Anesthesia was induced with inhalation of sevoflurane in combination with nitrous oxide and oxygen. The tracheal was not intubated. Anesthesia was maintained with sevoflurane, nitrous oxide and oxygen with continuous intravenous infusion of ketamine. The courses of anesthesia and the operations were uneventful. The most important point in the anesthetic management of the patient with this disease is to avoid mechanical stimulation to skin and mucous membrane.     

Closed system with agent-specific vaporizers and nitrous oxide

Through judicious use of nitrous oxide the closed system can be quite effectively used with currently available equipment including both agent-specific direct-reading percentage vaporizers and suitable devices for the measurement of end-tidal concentrations of oxygen, carbon dioxide and anaesthetic agents. It is only necessary to think in terms of required volumes of fresh gases and vapours added to the system as well as the appropriate concentrations of oxygen and anaesthetic in the respired mixture. When used as described the inspired concentration of nitrous oxide in the closed system should never exceed 50% (usually about 40%). Therefore nitrous oxide will not pose the threat of hypoxaemia unless misused. Experience in teaching this method during the previous decade supports a belief that learning the use of a truly closed circle absorption anaesthesia system is fundamentally important to the development of clinical skills and also facilitates understanding of basic concepts related to respiratory physiology and the uptake and distribution of inhalation anaesthetics. It follows that students and residents should be introduced to this method in the early weeks of their learning experience.     

Effects of thiopental and sevoflurane on hemodynamics during anesthetic management of electroconvulsive therapy

The effect of thiopental and sevoflurane (1 MAC, 2 MAC) on hemodynamics was assessed in a randomized study involving 38 adult patients undergoing electroconvulsive therapy (ECT). Blood pressure, heart rate and electrocardiogram (ECG) were monitored during the ECT procedure. After oxygenation, hypnosis was induced with a bolus injection of thiopenal (TPS) 4 mg.kg-1. Muscle relaxation was achieved by succinylcholine, 1 mg.kg-1 intravenously before ECT procedure. Ventilation was assisted using a face mask with 100% oxygen (TPS group), 1.7% sevoflurane (1 MAC group) or 3.4% sevoflurane (2 MAC group), plus 50% nitrous oxide and 50% oxygen. Thereafter, an electrical stimulus was administered. A total of 150 treatment sessions were evaluated. The rate pressure product increased in every group right after ECT, but the use of sevoflurane (2 MAC) significantly diminished the response compared with sevoflurane (1 MAC) and thiopental. In the sevoflurane (2 MAC) group, no ventricular arrhythmias were observed. In general, it seems that sevoflurane (2 MAC) is as effective as thiopental and sevoflurane (1 MAC) as an induction agent for ECT.     

Sevoflurane anaesthesia for a patient with adult polyglucosan body disease

PURPOSE: Adult polyglucosan body disease (APBD) is a rare neurological disorder of unknown cause characterized by four manifestations: upper motor neuron signs, peripheral neuropathy with motor and sensory loss, urinary incontinence, and dementia. The purpose of this report is to present a patient with APBD anaesthetized successfully with sevoflurane and nitrous oxide. CLINICAL FEATURE: A 51-yr-old man with APBD was scheduled for haemorrhoidectomy. Paraesthesia, dysaesthesia, distal muscular atrophy and fasciculation were recognized in the extremities. Dementia, bulbar paralysis and respiratory insufficiency were basent. Anaesthesia was induced with inhalation of sevoflurane and nitrous oxide, and the trachea was intubated without the use of muscle relaxants. Maintenance of anaesthesia was performed with sevoflurane (inspired concentration: 1.5-2.5%) and nitrous oxide (50%). Emergence from anaesthesia and the postoperative course were uneventful, and no exacerbation of neurological signs and symptoms was recognized. No postoperative analgesia was required. CONCLUSION: General anaesthesia and tracheal intubation with sevoflurane and nitrous oxide provided safe anaesthesia for a patient with APBD.     

Anesthesia for a child with congenital sensory neuropathy with anhydrosis]

We gave anesthesia twice to a 4-year-old boy with congenital sensory neuropathy with anhydrosis. At the first surgery, anesthesia was induced with midazolam and maintained with nitrous oxide, oxygen and sevoflurane 0.5-0.8% under mask breathing. Surgery was performed without any trouble but the patient vomited postoperatively for three days. Next time, anesthesia was induced and maintained with propofol under mask. The patient often moved during surgery, and therefore, we changed from propofol to oxygen and sevoflurane 1.0-1.5% anesthesia. Nitrous oxide was not used. After the surgery, no vomiting occurred.     

Rhabdomyolysis induced by succinylcholine chloride and sevoflurane in an elderly man

An 81-year-old man was scheduled for cervical lymph node biopsy. His laboratory data were within normal ranges. After induction of anesthesia with thiopental 175 mg and succinylcholine chloride (SCC) 40 mg, moderate masseter spasm was observed. Anesthesia was maintained with nitrous oxide, oxygen and sevoflurane. After the operation he had severe muscle pain and CK was elevated up to 81,400IU.l-1. The body temperature was not elevated above 37.2 degrees C during and after the operation. The skinned fiber examination, performed one month later, showed his calcium-induced-calcium-release (CICR) to be within normal ranges. We diagnosed him as rhabdomyolysis induced by coadministration of SCC and sevoflurane, especially SCC. We concluded that even in an elderly man, SCC should be administered cautiously.