Comparison of propofol and sevoflurane for laryngeal mask airway insertion in elderly patients.
Background: Sevoflurane and propofol have been widely used for anesthesia induction. This study compared the efficacies of sevoflurane and propofol inductions for laryngeal mask airway Invention and development
The first laryngeal mask airway, the LMATM airway, was invented in the 1980s by the British anaesthetist, Dr. Archie Brain. Since their introduction twenty plus years ago as a safe, effective alternative to the endotracheal tube doctors and (LMA LMA left mentoanterior (position of fetus). ) insertion in elderly patients.
Methods: Ninety patients, aged 60 or more, received anesthesia induction with propofol and with sevoflurane 8% using the vital capacity breath (VCB VCB Vietcombank (Bank for Foreign Trade of Vietnam)
VCB VMware Consolidated Backup
VCB Visitor and Convention Bureau
VCB Vacuum Circuit Breaker
VCB Value Control Box
VCB Virginia Commerce Bank ) or tidal volume tidal volume
The volume of air inspired or expired in a single breath during regular breathing. Also called tidal air.
n breath (TVB TVB Television Bureau
TVB Ti Voglio Bene (Italian: I Love You)
TVB Television Bureau of Advertising
TVB Television Broadcasts Limited (Hong Kong)
TVB Top Vs. ) techniques. Hemodynamic he·mo·dy·nam·ics
n. (used with a sing. verb)
The study of the forces involved in the circulation of blood.
he changes, induction time, complications, and the quality and ease of LMA insertion were observed.
Results: LMA was inserted most, less or least rapidly with propofol (89 [+ or -] 28 s), sevoflurane 8% using the VCB (163 [+ or -] 34 s) or TVB (205 [+ or -] 44 s) techniques, respectively. Anesthesia induction with propofol or sevoflurane 8% using the VCB technique produced either more frequent apnea or greater reduction in mean blood pressure than with sevoflurane 8% using the TVB technique.
Conclusions: Sevoflurane 8% using the TVB technique provides a smoother induction with a stable hemodynamic profile, less apnea and technical demand, but requiring longer time for LMA insertion in unpremedicated elderly patients.
Key Words: laryngeal mask airway, propofol, sevoflurane, elderly patients
The popular method of anesthetic induction for laryngeal mask airway (LMA) insertion is the use of intravenous (IV) propofol, which has the advantages of rapid onset, short duration of action and depression of upper airway up·per airway
The portion of the respiratory tract that extends from the nostrils or mouth through the larynx. reflex. (1) However, several adverse effects have been associated with propofol, including hypotension hypotension
or low blood pressure
Condition in which blood pressure is abnormally low. It may result from reduced blood volume (e.g., from heavy bleeding or plasma loss after severe burns) or increased blood-vessel capacity (e.g., in syncope). , apnea and pain on injection. (2) Sevoflurane seems to be an ideal agent for inhalational anesthesia induction. It improves the conditions of anesthesia induction in comparison with the other volatile agents. (3-5) Recently, sevoflurane inhaled induction with vital capacity breath (VCB) has been used as an alternative to IV induction in adults. (6) This method is featured by little excitatory ex·ci·ta·tive or ex·ci·ta·to·ry
Causing or tending to cause excitation.
Adj. 1. excitatory - (of drugs e.g. phenomena, high patient acceptance and good hemodynamic stability. (7) LMA insertion with VCB induction was proved to be effective and less costly as compared with propofol induction. (6) However, fewer relevant studies have focused on the elderly patients who are physiologically characteristic of limited cardiovascular and respiratory reserve. (8,9) These patients are at high risk of perioperative perioperative /peri·op·er·a·tive/ (-op´er-ah-tiv) pertaining to the period extending from the time of hospitalization for surgery to the time of discharge.
adj. cardiovascular accidents. Maintaining a stable hemodynamic state during induction has therefore become important for minimizing such adverse events in this population. (9)
In this study, we aimed to investigate which of the following commonly used techniques would best provide smooth induction for LMA insertion in the elderly: 1) IV induction with propofol; 2) sevoflurane 8% induction using the VCB technique; and 3) sevoflurane 8% induction using the tidal volume breath (TVB) technique.
Materials and Methods
With approval of the Ethics Committee ethics committee A multidisciplinary hospital body composed of a broad spectrum of personnel–eg, physicians, nurses, social workers, priests, and others, which addresses the moral and ethical issues within the hospital. See DNR, Institutional review board. of Harbin Medical University and written informed consent, a total of 90 patients were involved in this study, who underwent elective urological, orthopedic or general surgery, aged 60 years or more, ASA Asa (ā`sə), in the Bible, king of Judah, son and successor of Abijah. He was a good king, zealous in his extirpation of idols. When Baasha of Israel took Ramah (a few miles N of Jerusalem), Asa bought the help of Benhadad of Damascus and physical status I-III. Exclusion criteria exclusion criteria AIDS Donor exclusion criteria, see there included heavy smokers (20 cigarettes per day), severe or uncontrolled cardiovascular diseases requiring drug treatment, asthma with an attack within a month and severe respiratory disease with pulse oxygen saturation oxygen saturation sO2 The O2 concentration of blood expressed as a ratio of its total O2-carrying capacity; the OS is a measure of the utilization of O2 transport capacity; sO2 (Sp[O.sub.2]) of less than 94% while breathing room air, a known and suspected difficult airway or gastroesophageal reflux gastroesophageal reflux
A backflow of the contents of the stomach into the esophagus, caused by relaxation of the lower esophageal sphincter. Also called esophageal reflux, gastric reflux. . Those with hepatic, renal or neuromuscular diseases were also excluded. In addition, patients were excluded if systolic Systolic
The phase of blood circulation in which the heart's pumping chambers (ventricles) are actively pumping blood. The ventricles are squeezing (contracting) forcefully, and the pressure against the walls of the arteries is at its highest. or diastolic blood pressure Diastolic blood pressure
Blood pressure when the heart is resting between beats.
Mentioned in: Hypertension were above 180 or 110 mm Hg, respectively. Patients were within 15% of ideal body weight [Ideal body weight = 50 or 45.5 kg (for male or female) + 2.3 kg for each inch over 5 feet]. All subjects were allocated randomly by closed envelope technique to one of three groups: 1) Group IVP IVP
IVP (Intravenous pyelogram)
The use of a dye, injected into the veins, used to locate kidney stones. Also used to determine the anatomy of the urinary system. , n = 30; 2) Group VCB, n = 30; 3) Group TVB, n = 30.
Patients fasted overnight and were kept normothermic. No patients received premedication premedication /pre·med·i·ca·tion/ (pre?med-i-ka´shun)
1. preliminary administration of a drug preceding a diagnostic, therapeutic, or surgical procedure, as an antibiotic or antianxiety agent.
2. . At admission to the operation room, peripheral IV cannula cannula /can·nu·la/ (kan´u-lah) a tube for insertion into a vessel, duct, or cavity; during insertion its lumen is usually occupied by a trocar.
can·nu·la or can·u·la
n. pl. was inserted, and a slow infusion of lactated Ringer solution was started. Noninvasive blood pressure, electrocardiogram electrocardiogram /elec·tro·car·dio·gram/ (-kahr´de-o-gram?) a graphic tracing of the variations in electrical potential caused by the excitation of the heart muscle and detected at the body surface. and pulse oxygen saturation (Sp[O.sub.2]) monitoring were applied (Cardiocap, Datex Instrumentarium, Helsinki, Finland). Patients involved were given a weighted 20 mL syringe to hold. (10) Before anesthesia induction, the patients were preoxygenated for 3 minutes.
In Group IVP, anesthesia was induced with constant IV infusion of propofol (10 mg/mL) at a rate of 16 mL/min accompanied by injection of lidocaine lidocaine /li·do·caine/ (li´do-kan) an anesthetic with sedative, analgesic, and cardiac depressant properties, applied topically in the form of the base or hydrochloride salt as a local anesthetic; also used in the latter form as a 0.3 mg/kg through a three-way stopcock stopcock
a valve that regulates the flow of fluid through a tube. , which was continued until the patient dropped the weighted object. Although lidocaine was administrated as prophylaxis prophylaxis (prō'fĭlăk`sĭs), measures designed to prevent the occurrence of disease or its dissemination. Some examples of prophylaxis are immunization against serious diseases such as smallpox or diphtheria; quarantine to confine against pain on injection of propofol, it was used in the three groups because of its possible effect on hemodynamic variables. The patients were asked if they felt any pain through induction before loss of consciousness (no response to verbal commands). The procedures of LMA insertion were followed as described by Ti et al (11) Briefly, the ease of mouth opening was assessed (possible and impossible) and, if possible, LMA insertion was attempted by an anesthesiologist Anesthesiologist
A medical specialist who administers an anesthetic to a patient before he is treated.
Mentioned in: Anesthesia, General, Appendectomy, Parathyroidectomy
anesthesiologist . If impossible, repeat attempts were made every 30 seconds up to a maximum of three attempts; each time preceded by propofol boluses of 0.05 mL/kg. Each assessment for mouth opening was considered an attempt at insertion.
For patients in Group VCB, a circle C[O.sub.2] absorber circuit with a 4-L reservoir bag reservoir bag
See breathing bag.
n a repository for excess gas that is attached to an anesthesia machine. was used. The circuit was primed with sevoflurane 8% (dialed concentration) in a 2:1 ratio of nitrous oxide nitrous oxide or nitrogen (I) oxide, chemical compound, N2O, a colorless gas with a sweetish taste and odor. Its density is 1.977 grams per liter at STP. It is soluble in water, alcohol, ether, and other solvents. to oxygen at a fresh gas flow Fresh gas flow refers to the mixture of medical gases and volatile anaesthetic agents which is produced by an anaesthetic machine. The flow rate and composition of the fresh gas flow is determined by the anaesthetist. of 6 L/min for 3 minutes. Preoxygenation with 100% oxygen was performed via an additional circuit and oxygen source. Before the start of induction, the patient was instructed to exhale exhale /ex·hale/ (eks´hal) to breathe out.
1. To breathe out.
2. To emit a gas, vapor, or odor. maximally to residual volume residual volume
n. Abbr. RV
The volume of air remaining in the lungs after a maximal expiratory effort. Also called residual air, residual capacity. . Then, a well-fit mask connected with the primed circuit was placed firmly over the patient's face. The patient was asked to breathe in as deeply as possible and hold it as long as he or she could. If necessary, second and third vital capacity breaths were taken until loss of consciousness. When the patient dropped the weighted object, the ease of mouth opening was evaluated, and LMA insertion was attempted as described above. But between attempts, anesthesia was maintained with sevoflurane at a dialed concentration of 8% and nitrous oxide 67% in oxygen rather than propofol infusion.
In Group TVB, the patients were induced by taking normal breaths of a mixture of sevoflurane 8% (dialed concentration) in a 2:1 ratio of nitrous oxide to oxygen at a fresh gas flow of 6 L/min through a circuit without priming. The procedures for the assessment of mouth opening and LMA insertion were the same as described above.
Anesthesia induction and LMA insertion were performed by the same anesthesiologist familiar with the VCB and TVB induction techniques. Observations were made by an independent, but not blinded, investigator. A size 3 or 4 LMA (LMA Co. Limited, UK) was used for patients weighing <70 kg or >70 kg, respectively, regardless of gender. Any failures of insertion were rescued with succinylcholine succinylcholine /suc·ci·nyl·cho·line/ (suk?si-nil-ko´len) a depolarizing neuromuscular blocking agent used as the chloride salt as an anesthesia adjunct and in convulsive therapy. 50 mg IV. After the LMA was successfully inserted, all patients were given sevoflurane 4.0% in 67% nitrous oxide in oxygen at a fresh gas flow rate of 3 L/min for 3 minutes before decreasing the dialed concentration of sevoflurane to 2% for maintenance. Throughout the study, no controlled or assisted ventilation was given unless the patient had an Sp[O.sub.2] of less than 90%.
Two induction times were recorded as follows: 1) from initial breathing of sevoflurane or starting infusion of propofol (the start of induction) to dropping the object (T1); and 2) to successful LMA insertion (LMA was placed into the right position to maintain a patent airway without patients showing any severe or significant involuntary movements and/or adverse airway events) (T2). The readings of mean blood pressure (MBP (Manchester Bus Powered) A synchronous transmission standard used in industrial networks. It provides 31.25 Kbps over a two-wire connection that delivers power in the bus and intrinsic safety. ), heart rate (HR) and Sp[O.sub.2] were recorded before induction (baseline values) and at 1 minute intervals for 5 minutes from the start of induction. The independent investigator independent investigator Independent research investigator NIHspeak
A well-established scientist whose research accomplishments have resulted in the bestowal of "tenure", ie, long-term commitment of salary, personnel and research resources noted the presence of complications related to anesthetic induction and LMA insertion which included involuntary movements (excitatory movement or withdrawal from pain on injection), coughing, gagging, apnea (defined as absence of spontaneous respiration of more than 30 s; in Group VCB, apnea was assessed after the patient became unconscious) and laryngospasm.
Sample size was estimated by using a 2-side [alpha]-level of 0.05 and a power of 0.8. Based on our preliminary trial, the mean maximal decreases of MBP were 11.5 [+ or -] 6.8, 20.6 [+ or -] 8.4, 17.2 [+ or -] 7.1 mm Hg in groups TVB, IVP and VCB, respectively. Using these data to detect a difference among three groups, at least 20 subjects were required in each group. We included a total of 90 patients in the study for a more reliable statistical result.
Statistical calculations were performed using a personal computer statistical software package (Prism version 4.0; GraphPad Software, San Diego, CA). Values were expressed as mean [+ or -] SD (95% CI). Hemodynamics hemodynamics /he·mo·dy·nam·ics/ (-di-nam´iks) the study of the movements of blood and of the forces concerned.hemodynam´ic
n. were analyzed using two-way analysis of variance with Bonferroni post hoc test for multiple comparisons if significant F ratios were observed. The other quantitative data were analyzed using analysis of variance with a Student-Newman-Keuls post hoc test for multiple comparisons. Qualitative data were compared using [chi square chi square (kī),
n a nonparametric statistic used with discrete data in the form of frequency count (nominal data) or percentages or proportions that can be reduced to frequencies. ] test and Fisher exact test as appropriate. P < 0.05 was considered as statistically significant.
The three groups were comparable with respect to patient characteristics (Table 1). Failures of LMA insertion occurred in three patients in Group IVP and one patient in Group TVB because of an impossible mouth opening after three attempts. LMA insertions in these four patients were rescued successfully with succinylcholine. These patients were included in the analysis of the variables of patient characteristics, anesthesia induction, and overall success rate, but excluded from the analysis pertaining to speed and quality of LMA insertion and hemodynamic changes. Fewer attempts were required in Group IVP than in Groups TVB and VCB (1.2 vs. 1.9 vs. 1.7 attempts, respectively, P < 0.05) (Fig. 1). The three groups did not differ significantly in the successful rates of LMA insertion. The average consumption of propofol was 161 [+ or -] 35 mg.
The time to dropping the weighted object was significantly shorter in Group IVP than in the other groups and shorter in Group VCB as compared with Group TVB (IVP versus TVB P < 0.001; IVP versus VCB P < 0.001; VCB vs. TVB P < 0.001). The fast, intermediate and slow successful LMA insertions were achieved with propofol induction, VCB and TVB techniques, respectively (IVP versus TVB P < 0.001; IVP versus VCB P < 0.001; VCB versus TVB P < 0.001) (Table 2).
[FIGURE 1 OMITTED]
Complications Related to Induction and LMA Insertion
Throughout the study period, the most frequent untoward event was apnea, the incidences of which were higher in Group IVP than in Groups TVB and VCB during both anesthesia induction (IVP versus TVB P = 0.0002; IVP versus VCB P = 0.0379) and LMA insertion (IVP versus TVB P < 0.0001; IVP versus VCB P < 0.0001) but were comparable in the two latter groups (Table 3). In no patient did the apnea continue for longer than 1 minute, and none required assistant ventilation. There were no significant differences in the incidences of the other complications among the three groups. Although laryngospasm occurred in five patients of Groups TVB and VCB, it resolved spontaneously and did not disrupt the induction process. None of the patients with apnea and laryngospasm developed hypoxemia hypoxemia /hy·pox·emia/ (hi?pok-sem´e-ah) deficient oxygenation of the blood.
Insufficient oxygenation of arterial blood. (Sp[O.sub.2] <90%). In Group VCB, two patients had minimum oxygen saturations of 89% and 88%, respectively; in each case, the low saturation was corrected by manual ventilation man·u·al ventilation
A method of assisted or controlled ventilation in which the hands are used to generate airway pressures. . About 30% of patients complained of pain during propofol induction despite the use of lidocaine in Group IVP.
MBP showed significant decreases after anesthetic induction in Groups IVP and VCB. It was lower at 3, 4, and 5 minutes from the start of induction in Group IVP (87 [+ or -] 17, 85 [+ or -] 13 and 84 [+ or -] 15 mm Hg, respectively) as compared with Group TVB (99 [+ or -] 18, 101 [+ or -] 15 and 105 [+ or -] 16 mm Hg, respectively) (P < 0.05, P < 0.001 and P < 0.001, respectively) and lower at 4 and 5 minutes in Group IVP as compared with Group VCB (96 [+ or -] 13 and 98 [+ or -] 17 mm Hg, respectively) (P < 0.05 and P < 0.01, respectively). Although only at 2 minutes, MBP was significantly decreased in Group VCB than in Group TVB (87 [+ or -] 13 versus 9 [+ or -] 15, P < 0.05); compared with the baseline values, the mean maximal reduction of MBP was much smaller in Group TVB (10.6 [+ or -] 4.5 mm Hg) than in Groups VCB (16.8 [+ or -] 6.4 mm Hg) and IVP (20.9 [+ or -] 7.3 mm Hg) (IVP versus TVB P < 0.001; IVP versus VCB P < 0.05; VCB versus TVB P < 0.001). HR remained relatively stable during the whole study period in the three groups.
Our results showed that the three induction methods involved in this study were all effective for LMA insertion in elderly patients. Although anesthesia induction with propofol allowed a more rapid speed of LMA insertion, it was associated with more complications with apnea and pain on injection being the prominent drawbacks. Furthermore, compared with sevoflurane inhalation techniques, MBP exhibited a larger change with propofol induction, although propofol was given at a constant infusion rate instead of a single bolus bolus /bo·lus/ (bo´lus)
1. a rounded mass of food or pharmaceutical preparation ready to swallow, or such a mass passing through the gastrointestinal tract.
2. a concentrated mass of pharmaceutical preparation, e. administration. This result corresponds to others. (11-13) Ti et al (11) found in the investigation on LMA insertion in adults that propofol induction was associated with a greater drop in mean arterial pressure The mean arterial pressure (MAP) is a term used in medicine to describe a notional average blood pressure in an individual. It is defined as the average arterial pressure during a single cardiac cycle. Calculation (MAP) than 8% sevoflurane-VCB technique. Thwaites Thwaites may refer to:
The transition from induction to maintenance in Groups TVB and VCB was significantly smoother, which was demonstrated by no apnea associated with LMA insertion, than in Group IVP. This difference can be attributed to the fact that during inhalational anesthetic induction, the inspired and alveolar alveolar /al·ve·o·lar/ (al-ve´o-lar) [L. alveolaris ] pertaining to an alveolus.
Relating to an alveolus. concentrations of the volatile agent are almost equilibrated so that subsequent small changes in the depth of anesthesia are readily achieved. In contrast, after IV drug induction, rapid distribution of the drug may lead to a decrease in the depth of anesthesia. (12)
In young adults, the combining use of sevoflurane 8% in nitrous oxide and the VCB technique provided rapid induction and low complications, but also was associated with a reduction of approximately 20% of the preinduction value in systolic arterial pressure. (7,12) The myocardial myocardial /myo·car·di·al/ (-kahr´de-al) pertaining to the muscular tissue of the heart.
pertaining to the muscular tissue of the heart (the myocardium). depression occurs with high concentrations of sevoflurane, as a result of an effect on calcium channels. (17) Elderly patients are more subject to cardiovascular depression with volatile agents. (8,9,13) In the Yamaguchi et al (13) study on sevoflurane induction, compared with the traditional VCB technique, a new technique using a gradual reduction of concentration largely prevented the decrease in MAP. In our study, the mean maximal reduction in MBP was smaller with the TVB technique than with the VCB technique. The cause may be that the VCB led to an instant increase to a high alveolar sevoflurane concentration, whereas the TVB made sevoflurane reach a maximum more slowly, thereby minimizing the hemodynamic effect of sevoflurane. Such differences may not be of great clinical significance for healthy patients, but for the elderly who usually suffer from cardiovascular diseases, the relative hypotension appears to be dangerous. In addition, the VCB technique required the cooperation of patients. Elderly patients are usually unable to hold a vital capacity breath for a sufficient length of time because of inadequate cardiovascular and respiratory reserve. Walpole and Logan (8) indicated that elderly patients might have difficulty in holding a breath for 30 seconds or more and reported a modified vital capacity inhalation induction. In this study, most patients required second and third vital capacity breaths.
Another problem with the VCB technique is related to preoxygenation. Although it had been proven that even in elderly patients, oxygen saturation was well maintained throughout induction with sevoflurane in 50% nitrous oxide because of the presence of a vital capacity volume of 50% oxygen in the lungs as induction began, (8) theoretically, the main oxygen store exists in the functional residual capacity functional residual capacity
n. Abbr. FRC
The volume of gas remaining in the lungs at the end of a normal expiration. Also called functional residual air. of lung (FRC FRC
functional residual capacity
see functional residual capacity. ), and thus all techniques of preoxygenation should be based on denitrogenation of FRC, using 100% oxygen. (18) On the consideration that many elderly patients may suffer from pulmonary dysfunction, the traditional technique of preoxygenation is preferred. Indeed, several studies have shown that the time to desaturation desaturation /de·sat·u·ra·tion/ (de-sach?ah-ra´shun) the process of converting a saturated compound to one that is unsaturated, such as the introduction of a double bond between carbon atoms of a fatty acid. after preoxygenation via a few vital capacity breaths was significantly shorter compared with a longer period of tidal volume breathing of 100% oxygen. (19) In our study, two patients had minimum oxygen saturations of 89% and 88% in Group VCB, although the slow breathing frequency may be the main cause; inadequate preoxygenation also seemed to be a contributing factor.
In contrast, our results suggested that in unpremedicated elderly patients, anesthetic induction with sevoflurane 8% using the TVB technique was more likely to be an appropriate choice for LMA insertion. It offered better hemodynamic profiles with less apnea, smoother transition to the maintenance phase and no special requirements for patients, as also abolishing the breathing circuit priming and painful injection. When especially taking the cost and priming time into account, it was obviously superior to the VCB technique. The main disadvantage of it was a long period of time taken to establish the adequate anesthesia induction. The possible reason accounting for this is that for a similar depth of anesthesia, propofol produced greater jaw relaxation than sevoflurane. (11)
Notwithstanding our results, it is noteworthy that the depth of anesthesia among the three groups in this study is not compared. The use of electroencephalographic-related technology is likely to be helpful in resolving this problem, but the correlation between sevoflurane anesthesia and adequate anesthesia to prevent movement using electroencephalographic e·lec·tro·en·ceph·a·lo·graph
n. Abbr. EEG
An instrument that measures electrical potentials on the scalp and generates a record of the electrical activity of the brain. Also called encephalograph. derivatives has not been clearly defined. In many situations, LMA placement is preceded by opioid administration, which helps reduce the excitatory phenomena but probably exerts a synergistic cardiac depressant depressant, any one of various substances that diminish functional activity, usually by depressing the nervous system. Barbiturates, sedatives, alcohol, and meprobamate are all depressants. Depressants have various modes of action and effects. effect when sevoflurane is combined. (15) We did not use opioids to keep a clear comparison between propofol and sevoflurane induction techniques. One limitation of our study regards a possible observer bias. But the incidence of successful LMA insertion and apnea are all related to such a bias or various time definitions.
Our results demonstrate that although anesthetic induction with sevoflurane 8% using the TVB or VCB techniques take longer time and more attempts to complete LMA insertion in unpremedicated elderly patients as compared with propofol induction, they are associated with less frequent apnea and hypotension. The TVB technique is more likely to maintain cardiovascular stability, as it also might be less costly and technically demanding because of no need for circuit priming and patient cooperation; however, it seems to be more time consuming for LMA insertion than the VCB technique.
We would like to acknowledge Professor FuShan Xue for reviewing the manuscript and providing valuable advice.
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la·ryn·geal or la·ryn·gal
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PCW Post Consumer Waste
PCW Polichlorek Winylu (Polish: Polyvinyl chloride)
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The moment one gives close attention to anything, even a blade of grass, it becomes a mysterious, awesome, indescribably magnificent world in itself. --Henry Miller
GuiQian Shao, MD, and GuoHua Zhang, MD
From the Department of Anesthesiology, the First Affiliated Hospital of Harbin Medical University, Harbin, China; and the Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College Peking Union Medical College, Tsinghua University (北京协和医学院，清华大学医学部)  is among the most selective medical colleges in the People's Republic of China and is renowned , Beijing, China.
Reprint requests to Dr. GuoHua Zhang, Department of Anesthesiology, Plastic Surgery Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Ba-Da-Chu Road, Shi-Jing-Shan District, Beijing, People's Republic of China 100041. Email: firstname.lastname@example.org
Accepted October 18, 2006.
RELATED ARTICLE: Key Points
* Anesthesia inductions with propofol and with sevoflurane 8% using the vital capacity breath (VCB) or tidal volume breath (TVB) techniques can all provide clinically accepted conditions for laryngeal mask airway (LMA) insertion in elderly patients.
* Propofol induction offered more rapid LMA insertion with fewer attempts, but also greater reduction in mean blood pressure and more frequent apnea, compared with the two sevoflurane induction methods.
* Although sevoflurane 8% plus VCB technique took less time for insertion of LMA, it resulted in more pronounced hemodynamic changes and required extra patient cooperation and anesthesia circuit priming as compared to sevoflurane 8% plus TVB technique.
* Sevoflurane 8% plus TVB technique was able to provide smoother anesthesia induction for LMA insertion in elderly patients with fewer untoward events at the cost of longer induction time.
Table 1. Patient characteristics in the three groups Group IVP Group TVB Group VCB Number (n) 30 30 30 Age (yr) 71 [+ or -] 6 70 [+ or -] 5 68 [+ or -] 7 Gender (M/F) 16/14 20/10 13/17 Weight (kg) 62.5 [+ or -] 11.9 68.8 [+ or -] 13.4 64.2 [+ or -] 10.7 ASA 7/22/1 5/24/1 3/25/2 (I/II/III) Smoker 6/24 9/21 5/25 (yes/no) Sp[O.sub.2] 97.0 [+ or -] 0.5 96.8 [+ or -] 0.6 97.1 [+ or -] 0.4 (%) Values are mean [+ or -] SD or number of patients. Table 2. Induction times in the three groups Groups T1(s) T2(s) (a) IVP 58 [+ or -] 15 [53-62] 89 [+ or -] 28 [78-99] TVB 145 [+ or -] 23 [136-152]* (#) 205 [+ or -] 44 [189-220]* (#) VCB 113 [+ or -] 19 [105-117]* 163 [+ or -] 34 [151-174]* (a) Three patients in Group IVP and one patient in Group TVB were excluded from analysis because of failures in LMA insertion within three attempts; Values are mean [+ or -] SD [95% CI]. *P < 0.05, compared with Group IVP; (#) P < 0.05, compared with Group VCB. Table 3. Events related to anesthesia induction and laryngeal mask airway (LMA) insertion Induction (No. of patients) Groups Apnea Coughing Laryngospasm Movements IVP 20 1 0 11 TVB 4* 4 2 4 VCB 11* 1 3 9 LMA insertion (a) (No. of patients) Groups Apnea Coughing Gagging Movements IVP 11 5 6 16 TVB 0* 1 4 12 VCB 0* 1 3 10 (a) Three patients in Group IVP and one patient in Group TVB were excluded from analysis because of failures in LMA insertion within three attempts. Values are numbers of patients. *P < 0.05, compared with Group IVP.