Background and Objective: Due to the high cost of scavenging systems, it is rare to find them in use in the hospitals of developing countries. This study was designed to determine the efficacy of a modified scavenging system for isoflurane for use in the Philippines Material and Methods: A modified scavenging system was constructed using a 500 ml of beaker glass with 100 ml of tap water, the opening tightly sealed with styropore. A single anesthesia machine, gas analyzer and isoflurane vaporizer were used in this study. Oxygen flow was set at one liter per minute. The isoflurane vaporizer was set at 2.5 volume percent. A corrugated tube conveys wasted gas into the beaker and allows the gas to bubble through the tap water. Another tube conveys bubbled gas from the beaker to the atmosphere. As soon as there is no change for at least 15 seconds in the numeric value and graphical representation of the MAC and volume percent of isoflurane in the gas analyzer, the reading was recorded as MAC-O minute and volume percent-0 minute. This was repeated every 15 minutes thereafter in the inlet port and every five minute in exit port until 60 minutes Results: The mean MAC and volume percent of isoflurane at point A and B were 1.1 versus 0.938461538 and 1.3 versus 1.158974359, respectively (t-test p0.05). At point B, all observation was statistically lower than the baseline (t-test p0.05) Conclusion: The MAC and volume percent of isoflurane were statistically lower at point B from 0 observation time until 60 minute observation time using the modified scavenging system. (Author)
ANESTHESIA, ISOFLURANE

Sevoflurane, a volatile halogenated ether, has been widely used in the conduct of anesthesia. Its potency, easy titratability, less pungency and rapid recovery are the reasons for its pervasive use in clinical practice. However, it is not without adverse effects. The nephrotoxicity associated with its use has been the subject of dispute over the years. At present, no highly sensitive renal marker has been the subject of dispute over the years. At present, no highly sensitive renal marker has been utilized to assess renal function. Objective: To compare the effect on renal function as measured by nuclear glomerular filtration rate, serum creatinine, urine protein creatinine ratio, proteinuria and glocosuria of sevoflurane with isoflurane in patients undergoing donor nephrectomy. Study Design and Methods: A randomized comparative study of postoperative renal functions as measured by nuclear glomerular filtration rate, serum creatinine, urine protein creatinine ratio, proteinuria and glucosuria in patients undergoing donor nephrectomies who have received low flow (<1 L/Min) sevoflurane or isoflurane were done. Results: A total of 102 kidney donors met the inclusion criteria. Forty seven subjects (46%) were randomized to receive isoflurane while 55 received sevoflurane (54%). Most subjects were in the third decade of life. There was no statistically significant difference between the two groups in terms of the baseline clinical characteristics. Comparing between the two anesthetic groups, there was no significant difference in terms of serum creatinine, total GFR, nuclear GFR per kidney. There was a statistically higher proportion of patients with urine protein- creatinine ratios of 0.2 and above in the isoflurane group (64% versus 38%) while more patients in the sevoflurane group had ratios above 0.2 (62% versus 36%, p=.045). The type of anesthetic agent was not an independent predictor of increasing serum creatinine, total GFR and urine protein- creatinine ratio and nuclear GFR assessed per kidney. Conclusion: There were no statistical differences noted in measured renal function parameters among patients undergoing donor nephrectomy after low flow sevoflurane compared with isoflurane anesthesia. These results suggest that low flow sevoflurane is as safe as low flow isoflurane and does not alter renal functions in patients for donor nephrectomy.
Human ; SEVOFLURANE ; NEPHRECTOMY ; ANESTHESIA ; ISOFLURANE

BACKGROUND: This study was doned to evaluate the rate of awakening after desflurane or isoflurane anesthesia in pediatric tonsillectomy patients. METHODS: Sixty patients, aged 5 10 years undergoing a tonsillectomy with or without an adenoidectomy were randomly assigned to receive either desflurane-N2O (group D) or isoflurane-N2O (group I). A recovery profile was assessed by a 3 point scale for the first 0, 15 and 30 min in the recovery room. RESULTS: It was statistically significant that group D had a shorter extubation time and eye opening time and a less apprehensive score than group I at 0, 15 and 30 min. CONCLUSIONS: We conclude that desflurane-N2O may offer clinical advantages over isoflurane when used for maintenance of anesthesia during a pediatric tonsillectomy.
Adenoidectomy ; Anesthesia ; Humans ; Isoflurane ; Recovery Room ; Tonsillectomy*

BACKGROUND: Monitoring of "Depth of anesthesia" is an ongoing problem in anaesthesia. In this study, the author has compared the bispectral index (BIS) and Anemon monitor for monitoring depth of anesthesia in propofol or isoflurane anesthesia. METHODS: Anemon-1 and BIS index were obtained from 24 patients (ASA I, II) during general anesthesia with propofol or isoflurane. For patients in the propofol group, anesthesia was induced with fentanyl 100ng followed by propofol 2 mg/Kg. For patients in the isoflurane group, anesthesia was induced with thiopental 5 mg/Kg. The author observed changes of these values at 5 major times: before induction, during induction, after induction, at sKin incision, before extubation, after extubation. RESULTS: The anemon index showed a significant increase during induction (propofol group: 86.9 +/- 26.4, isoflurane group: 106.0 +/- 18.6) and at sKin incision (propofol group: 89.9 +/- 22.7, isoflurane group: 92.0 +/- 23.1), but this did not correlate with the level of consciousness. The BIS index showed a significant decrease in the score after induction (propofol group: 55.0 +/- 9.6, isoflurane group: 61.0 +/- 17.2), but no response to surgical stimuli. CONCLUSIONS: BIS had a good correlation with level of consciousness. The Anemon-1 index was recognized to reflect invasive stimulus. As the BIS and Anemon-1 had no correlation, it was not possible to assume changes of each index from the other. Both the anemon-1 index and BIS are useful to monitor the anesthesia level during surgery.
Anesthesia ; Anesthesia, General ; Consciousness ; Fentanyl ; Humans ; Isoflurane ; Propofol ; Skin ; Thiopental

BACKGROUND: Sevoflurane and desflurane are widely used anesthetics and can be simulated in pharmacokinetic models. These models are related to steady state pharmacokinetics, As anesthetic elimination is a non-steady state process, we evaluated the elimination data of volatile anesthetics using a two-compartment model (bi-exponential function). 50, 80, and 90% context-sensitive decrement times were evaluated with this function. These times are related to awakening and cognitive function recovery. METHODS: Forty-eight healthy patients were enrolled for minimal surgery under general anesthesia. They were randomly anesthetized with either sevoflurane or desflurane. At the end of surgery, when the administration of the volatile anesthetics was discontinued, end-tidal concentrations (PE) were recorded for 15 minutes. We calculated and analyzed the fraction of anesthetic concentrations (PE/PE0) using a bi-exponential function (PE0: the last end-tidal concentration of anesthetics during anesthesia). RESULTS: A bi-exponential function was fit to the elimination data using non-linear mixed-effect modeling. It showed that the anesthetic duration had effects on the coefficients of early and late components and not on the log rate constants. The coefficient of late components increased and the coefficient of early components decreased with prolonged anesthetic duration. Irrespective to the type of anesthetics, prolonged anesthesia did not affect the context-sensitive half-life; however, a prolonged period of time was required to reach 80 and 90% decrement after prolonged anesthesia. CONCLUSIONS: Prolonged anesthetic duration slowed down the elimination of volatile anesthetics. It delayed awakeness and a return to normal cognitive function after anesthesia.
Anesthesia ; Anesthesia, General ; Anesthetics ; Humans ; Isoflurane ; Methyl Ethers

BACKGROUND: A circle system can be closed or semiclosed depending on the amount of fresh gas flow. A closed system is one in which the inflow gas exactly matches that being taken up or consumed by the patient. A semiclosed system is associated with partial rebreathing of gases and is the most commonly used system today. The purpose of this study is to examine the actual consumed amount of volatile anesthetic by closed and semiclosed anesthesia systems. METHODS: Forty-seven patients undergoing general inhalation anesthesia with enflurane and thirty-six patients with isoflurane were examined. Each group was divided into two subgroups by the circle system; enflurane-closed (33 patients), enflurane-semiclosed (14 patients), isoflurane-closed (23 patients), and isoflurane-semiclosed groups (13 patients). Closed system was performed by using PhysioFlex anesthesia machine. The difference of initial (just before anesthesia) and remained (just after anesthesia) enflurane or isoflurane volumes measured by 30 ml-syringe was obtained as consumed amount of anesthetics. This amount was calculated on the base of 1% enflurane or isoflurane for 1 hour anesthesia with a given fresh gas flow (4 to 5 L/min). RESULTS: Consumed amount of liquid enflurane and isoflurane when using closed system was 6.99 +/- 0.26 ml/hr and 4.84 +/- 0.27 ml/hr respectively while 15.99 +/- 1.48 ml/hr and 14.01 +/- 0.92 ml/hr respectively when using semiclosed system. Consumption of liquid anesthetics was significantly lower in closed anesthesia and significantly higher in both systems than those of predicted values. CONCLUSIONS: In closed system by using PhsioFlex anesthesia machine consumed amount of liquid anesthetic for 1 hour anesthesia with 1% of endtidal anesthetic concentration at 25 degrees C, 1 atm and 4 to 5 L/min of fresh gas flow was within 35 to 44% of that in semiclosed system.
Anesthesia* ; Anesthesia, Inhalation ; Anesthetics* ; Enflurane ; Gases ; Humans ; Isoflurane

BACKGROUND: A poincare plot of the heart rate variability (HRV) allows for the quantitative display of the vagal tone in conscious humans. However, relatively little is known about standard deviation 1 (SD1) from the poincare plot reflecting the vagal tone and correlating with the high frequency (HF) spectral power of the HRV during general anesthesia. Thus, the association of SD1 from the poincare plot was examined, along with the HF spectral power of the HRV during general anesthesia. METHODS: Beat-to-beat electrocardiograms were recorded for 5 min in 23 patients (isoflurane group, n = 13; sevoflurane group, n = 10) before, during and after general anesthesia. The low frequency (LF) and HF spectral powers, the LF/HF ratio of the HRV and the SD1 and standard deviation 2 (SD2) from the poincare plot were calculated. RESULTS: Both the HF spectral power of the HRV and SD1 from the poincare plot were reduced following general anesthesia, but recovered thereafter. The recovery of both the HF spectral power and SD1 from the poincare plot in the sevoflurane group was faster than those in the isoflurane group. There were strong correlations between the HF spectral power and SD1 before, during and after anesthesia. CONCLUSIONS: These data suggest that the SD1 from the poincare plot is a useful and valid parameter for analysis of the vagal tone during general anesthesia.
Anesthesia ; Anesthesia, General* ; Electrocardiography ; Heart Rate* ; Heart* ; Humans ; Isoflurane

BACKGROUND: The bispectral index (BIS) has been designed to objectively measure the degree of sedation and hypnosis for anesthesia. Although it has been well-known that BIS correlates highly with the concentration of inhalation anesthetics, it is not clear whether analgesic potency expressed as MAC is comparable to hypnotic potency described as BIS50 in inhaled anesthetics. This study was conducted to examine the degree of correspondence by correlating the changes of BIS according to the different MAC of commonly used inhalation anesthetics. METHODS: One hundred ASA class 1 or 2 patients, scheduled for laparoscopic knee surgery were included. Patients were equally divided into 4 groups (n = 25 each) according to the inhalational agent enflurane, isoflurane, desflurane, or sevoflurane. Anesthetic depth for each individual agent was controlled to 2.0, 1.75, 1.5, 1.25, 1.0, 0.75 and 0.5 MAC, respectively. After equilibration for each concentration, BIS values were measured three times at 30 second intervals and an average was obtained. In addition, MAC values for each agent were measured when the bispectral index showed 50. RESULTS: The concentrations of inhaled agents vs. BIS showed high negative correlations (enflurane; -0.91, isoflurane; -0.94, desflurane; -0.84, and sevoflurane; -0.86). BIS50 for each agent was enflurane, 0.93 (1.6 vol%); isoflurane, 0.71 (0.9 vol%); desflurane, 0.95 (5.7 vol%); and sevoflurane, 0.84 MAC (1.7 vol%). Isoflurane-BIS50 showed a significant difference to the others (P<0.05). CONCLUSIONS: We concluded that the MAC of inhalation anesthetics showed poor correlation with BIS, suggesting a difference between the hypnotic and analgesic potency of individual inhaled anesthetic agents.
Anesthesia ; Anesthetics ; Anesthetics, Inhalation* ; Enflurane ; Humans ; Hypnosis ; Inhalation* ; Isoflurane ; Knee

BACKGROUND: The administration of short-acting opioids before emergence is useful for preventing emergence cough induced by an endotracheal tube. This study examined the clinically effective dose of alfentanil for suppressing cough during emergence from desflurane anesthesia. METHODS: Twenty-nine adult patients undergoing elective oral surgery were enrolled in this study. During emergence from anesthesia, the patients received alfentanil diluted in 10 ml normal saline when the end-tidal vol% of desflurane decreased to 3%. The initial alfentanil dose was 16 microg/kg. The alfentanil dose for consecutive patients, determined by Dixon's up-and-down method, increased or decreased by 2 microg/kg according to a previous patient's result. RESULTS: The 50% effective dose (ED50) of alfentanil for suppressing cough during emergence from desflurane anaesthesia was 9.3 +/- 1.5 microg/kg according to Dixon's up-and-down method. Isotonic regression revealed an ED50 and ED95 (95% confidence interval) of alfentanil 10.0 microg/kg (6.8-13.2 microg/kg) and 14.0 microg/kg (7.7-19.4 microg/kg), respectively. CONCLUSIONS: The ED95 of alfentanil for suppressing emergence cough was 14.0 microg/kg. A single bolus administration of alfentanil during emergence from anesthesia was useful for suppressing emergence cough.
Adult ; Alfentanil ; Analgesics, Opioid ; Anesthesia ; Cough ; Humans ; Isoflurane ; Surgery, Oral

The effect of single dose clonidine premedication on the vapour requirement for isoflurane induced hypotension in 20 patients undergoing spine surgery was evaluated. The patients given 5 ug/kg of clonidine P.O. at 90 minutes before operation required a mean expired isoflurane concentration of 1.2+/-0.5 vol% to induce hypotension compared with 2.1+/-0.6 vol% in 0.2 mg/kg of diazepam predmedication group(P<0.05). To achieve satisfactory hypotension, six out of ten patients in diazepam premedication group and l out of 10 patients in clondine premedication group are required supplementary infusion of sodium nitroprusside. In conclusion, clonidine premedication is recommended in isoflurane induced hypotensive anesthesia.
Anesthesia* ; Clonidine* ; Diazepam ; Humans ; Hypotension ; Isoflurane* ; Nitroprusside ; Premedication* ; Spine