Vital capacity breath technique for rapid anaesthetic induction: comparison of sevoflurane and isoflurane

This study compares vital capacity rapid inhalational induction of anaesthesia with sevoflurane and isoflurane. Forty-six volunteers undergoing the procedure had one of the two agents: 25 had sevoflurane and 21 isoflurane. Subjects were unpremedicated and breathed approximately 1.7 MAC equivalents of either vapour. There were no significant differences in the patients' monitored cardiovascular, respiratory, and electrocardiographic variables. The mean time for induction of anaesthesia with sevoflurane (120 s) was significantly shorter than with isoflurane (145 s), reflecting its higher blood-gas solubility. There were fewer induction complications in the sevoflurane group. Subjects in the sevoflurane group found the induction of anaesthesia more pleasant and were more willing to undergo it again compared to subjects in the isoflurane group. We conclude that sevoflurane is superior to isoflurane in vital capacity rapid inhalational induction of anaesthesia, particularly in instances where premedication should be avoided.     

Vital capacity rapid inhalation induction (VCRII) technique with sevoflurane for a rheumatoid patient with difficult airway

Successful airway management in an adult female patient with limited cervical extension and a subluxation of bilateral jaw joints caused by rheumatoid arthritis was reported. We planned to reduce the intensity of pain in her right hand through neurolysis of the ulnar nerve in her right elbow joint. Right axillary nerve blockade with 1% lidocaine 10 ml and 0.25% bupivacaine 10 ml, was employed unsuccessfully to achieve adequate anesthetic effect. Anesthesia was administered using a vital capacity rapid inhalation induction (VCRII) technique with 5% sevoflurane in the oxygen. When the patient lost consciousness, a size 3 laryngeal mask airway (LMA) was inserted under spontaneous breathing on the first trial. There was very little hemodynamic change during the insertion of the LMA. Anesthesia was maintained with sevoflurane 1.5-2.0% in oxygen under spontaneous breathing. Emergence from anesthesia was rapid and no signs of upper airway obstruction were observed after the removal of the LMA. The use of the LMA with VCRII technique and anesthetic maintenance using sevoflurane, are likely to be an optional technique of airway management in patients with problematic airway.     

Vital capacity and patient controlled sevoflurane inhalation result in similar induction characteristics

PURPOSE: To compare patient controlled inhalational induction (PCI) with the most commonly used sevoflurane induction technique, vital capacity inhalational induction (VCI). METHODS: Following approval of the Research Ethics Board, 124 outpatients undergoing knee arthroscopy were randomly assigned to receive either PCI or VCI sevoflurane followed by laryngeal mask airway (LMA) insertion and sevoflurane maintenance. In the PCI group, the circle circuit was not primed. The patients were asked to hold the facemask themselves and breathe normally with sevoflurane 8% in oxygen at a flow rate of 4 L x min(-1). In the VCI group, the circle circuit was primed and patients were asked to take vital capacity breaths with sevoflurane 8% at an oxygen flow rate of 8 L x min(-1). The LMA was inserted as soon as the patient's jaw was relaxed. Time from induction to LMA insertion was recorded and insertion conditions rated. The amount of sevoflurane used for LMA insertion was calculated. Vital signs were monitored at one-minute intervals until ten minutes after LMA insertion. RESULTS: Demographic data were comparable. There were no differences with respect to LMA insertion time (PCI - 3.4 min vs VCI - 3.3 min), laryngospasm (PCI - 7% vs VCI - 5%), mean arterial pressure, heart rate, SaO(2) as well as patient's overall satisfaction. CONCLUSION: PCI was comparable to VCI in sevoflurane induction with respect to the speed of induction, side effects during induction and patient satisfaction. However, PCI requires no special training and is widely applicable to all patient populations.     

Bispectral monitoring during vital capacity rapid inhalation induction with sevoflurane

STUDY OBJECTIVE: To evaluate the variables of bispectral index (BIS) values during vital capacity rapid inhalation induction (VCRII) with sevoflurane. DESIGN: Randomized, prospective study. SETTING: University hospital. PATIENTS: 40 ASA physical status I and II patients scheduled for elective orthopedic surgery with general anesthesia. INTERVENTIONS: Patients was divided into two groups, both of which received intravenous (IV) injection of propofol 2 mg/kg followed by inhalation of sevoflurane 3% (Group P), or vital capacity inhalation induction with sevoflurane 8% (Group S). After loss of consciousness, tracheal intubation was performed with vecuronium 0.1 mg/kg. MEASUREMENTS AND MAIN RESULTS: The induction times in Group P were significantly shorter than those in Group S (p < 0.01). In Group S, BIS values were gradually decreased and maintained the adequate hypnotic levels were maintained during induction. In Group P, although BIS values were rapidly decreased, the values remained higher compared with Group S. The BIS value before intubation in Group S was significantly lower than that in Group P (25 +/- 9 and 38 +/- 7, respectively; p < 0.01). Five of 20 Group P patients had BIS values exceeding 60 before tracheal intubation, but no patient in Group S had a BIS value as high. Mean arterial pressure immediately after intubation in Group S was significantly lower than that in Group P (p < 0.05). CONCLUSION: VCRII with a high concentration of sevoflurane provided adequate BIS values during induction, suggesting that it may allow smoother transition from anesthesia induction to maintenance, and also maintain an adequate hypnotic level in readiness for certain stimuli such as laryngoscopy and tracheal intubation.     

Single-breath vital capacity rapid inhalation induction with sevoflurane: feasibility in children

BACKGROUND: Single-breath vital capacity technique is currently administered for inhalation induction of anesthesia with sevoflurane in adults. Because sevoflurane is used in children, the aim of this open nonrandomized trial was to explore the feasibility and acceptance of this technique in midazolam premedicated patients aged from 4 to 15 years old. METHODS: A pediatric population (n = 118) was instructed in the vital capacity technique after their arrival in the induction room in a standardized and playful manner. Induction was performed with a circle-absorber breathing circuit, primed with sevoflurane 7% in 100% O2. Success of the single-breath vital capacity, delay of induction, hemodynamic and airway tolerance, acceptance by the children and side effects were analyzed. A multivariate logistic regression model was used to identify independent risk factors associated with the failure of the vital capacity technique. RESULTS: Single-breath vital capacity technique was achieved by 57% of the children. The success rate highly correlated with age and ranged from 10% in 4-5 years old to 75% at 11 years and 95% by 14 years. Other factors for success were cooperation and understanding. The need for more than two explanations of the technique was predictive of failure. Delays in the loss of the eyelash reflex and central pupil myosis were obtained in 34 s (18-50) and 242 s (145-278), respectively [median (interquartile ranges)]. Hemodynamic tolerance was good with few airway complications. CONCLUSION: Rapid anesthesia induction using a single-breath technique with 7% sevoflurane is effective and well tolerated in children, particularly in those above 9 years of age, and in fact, success rate was markedly lower in the young age groups.     

Vital capacity inhalation induction with sevoflurane: an alternative to standard intravenous induction for patients undergoing cardiac surgery

OBJECTIVE: To determine the respiratory and cardiovascular effects of a high concentration vital capacity induction with sevoflurane compared with an intravenous induction with etomidate in patients scheduled for elective coronary artery bypass graft (CABG) surgery. DESIGN: Prospective, randomized, double-blind, controlled clinical trial. SETTING: Cardiothoracic unit at a university hospital referral center. PARTICIPANTS: Twenty-two patients undergoing elective CABG surgery. INTERVENTIONS: The study group (group S) received a vital capacity gaseous induction with sevoflurane 8% (n = 12) and the control group (group E) were given etomidate, 0.2 to 0.3 mg/kg (n = 10). Anesthesia was supplemented with fentanyl, 8 microg/kg, and vecuronium, 0.1 mg/kg, in both groups. MEASUREMENTS AND MAIN RESULTS: The speed of induction of anesthesia was comparable between the groups. There was a significant increase in minute ventilation after induction of anesthesia in both groups. This increase was associated with a small reduction in PaCO2. There were no clinically significant changes in pH and PaO(2). The incidence of breath-holding and the need for an oropharyngeal airway were similar between the groups. Both groups had similar reductions in mean arterial pressure and cardiac output during the study period; however, a downward trend in mean pulmonary artery pressure was noted in group S, whereas in group E it remained unchanged. Absolute plasma epinephrine and norepinephrine values were low during the precardiopulmonary bypass period in both groups. CONCLUSIONS: The technique of vital capacity inhalation induction with 8% sevoflurane offers a rapid onset of anesthesia, satisfactory airway control, and a good hemodynamic profile. Consideration should be given to the benefits of single-agent anesthesia and lowered pulmonary artery pressure during the precardiopulmonary bypass period. In addition to CABG surgery, this technique could be considered in patients with coronary artery disease undergoing noncardiac surgery, particularly for procedures in which spontaneous ventilation is preferred.     

Conventional stepwise vs. vital capacity rapid inhalation induction at two concentrations of sevoflurane

BACKGROUND AND OBJECTIVE: A multicentre study was conducted to compare three methods of inhalation induction with sevoflurane in adult premedicated patients. METHODS: One-hundred-and-twenty-five adult patients of ASA I-II were scheduled for short elective surgical procedures (< 90 min) under general anaesthesia with spontaneous ventilation of the lungs via a laryngeal mask airway. Patients were randomly assigned to one of three groups: conventional stepwise inhalation induction group (Group C) or vital capacity rapid inhalation induction groups at 4.5% (Group VC4.5) or at 8% sevoflurane (Group VC8). Before anaesthetic induction, fentanyl 1 micro kg(-1) was given and the face mask applied with the anaesthetic breathing system primed with sevoflurane 4.5% or 8% in the respective vital capacity groups. Loss of eyelash reflex, time to cessation of finger tapping, laryngeal mask insertion, side-effects and adequacy of induction were recorded. RESULTS: The time to loss of eyelash reflex was significantly shorter in both vital capacity groups vs. the control group: VC8: 68 +/- 7 s; and VC4.5: 94 +/- 6.5 s vs. C: 118 +/- 6.4s (P < 0.0001). Significant differences were found in all pairwise comparisons for time to cessation of tapping: Group VC8 (62 +/- 7 s), Group VC4.5 (85 +/- 6 s) and Group C (116 +/- 6 s; P < 0.0001). The time to laryngeal mask insertion was significantly shorter in the Group VC8 (176 +/- 13 s) compared with the other two groups, Group VC4.5 (219 +/- 13 s) and Group C (216 +/- 9 s). There were no significant differences in the incidence of side-effects between the three groups. CONCLUSIONS: Inhalation induction of anaesthesia with sevoflurane with the three techniques tested is safe, reliable and well accepted by the patients. The vital capacity rapid inhalation group primed with sevoflurane 8% was the fastest method with no relevant side-effects.     

Comparison between halothane and sevoflurane for adult vital capacity induction

We have examined the differences in ventilatory characteristics between halothane and sevoflurane when used for adult vital capacity induction of anaesthesia. The study was conducted in a randomized, double-blind manner. After 13 patients had been enrolled, the study was curtailed because the blinded observer thought that there was an unacceptably high incidence of adverse events. After the randomization code was revealed, the adverse events were found to be in the halothane group. Although the sample size was small, minute volumes appeared to be maintained in the sevoflurane group. Ventilatory frequencies were similar in the two groups after insertion of the laryngeal mask airway, but tidal volumes were significantly greater in the sevoflurane group (P = 0.0013).      

Rapid inhalation induction in children: 8% sevoflurane compared with 5% halothane

Sevoflurane has a lower blood-gas solubility and a less pungent odour than halothane; this may allow more rapid induction of anaesthesia. In a randomized, blinded study, we compared the induction characteristics of maximum initial inspired concentration of 8% sevoflurane and 5% halothane using conventional vaporizers in children aged 3 months to 3 years. There was no statistically significant difference in induction times between the two groups: mean times to loss of consciousness were 1 min 12 s (SD 18 s, range 40 s-1 min 44 s) for sevoflurane and 1 min 16 s (SD 17 s, range 50 s-1 min 52 s) for halothane, although these times were shorter than in previous studies using a gradual increase in vapour concentration. A small number of complications were noted in both groups, although none interfered with induction of anaesthesia. Struggling scores were lower in the sevoflurane group than in the halothane group (chi-square for trends = 6.34, P < 0.02). A significant number (11 of 15) of parents of children in the sevoflurane group who had previous experience of halothane induction preferred sevoflurane (chi-square for trends = 4.03, P < 0.05). We conclude that with this technique, induction was rapid with both sevoflurane and halothane. Our assessment of patient struggling and parents' perceptions suggests that induction with sevoflurane was more pleasant than with halothane.      

小儿七氟醚和异氟醚快速吸入诱导的比较

目的:比较小儿使用高浓度七氟醚和异氟醚加氧化亚氮快速吸入诱导的区别。方法:38例4～11岁,未使用术前药小儿随机分为二组,七氟醚组(n=20),吸入5％七氟醚,60％氧化亚氮;异氟醚组(n=18)吸入3.5％异氟醚,60％氧化亚氮。观察两组小儿采用快速吸入诱导方法时,睫毛反射和疼痛反应消失时间,以及药物的刺激性和诱导平稳程度的区别;同时观察两种方法对小儿循环功能的影响。结果:七氟醚组的诱导效果较为满意,其睫毛反射时间,疼痛反应消失时间均明显快于异氟醚组,分别为63.45±16.27(秒),189.40±28.70(秒)和75.82±22.60(秒),231.62±77.74(秒)(P<0.01);异氟醚对气道的刺激性较大,小儿吸入时躲闪,咳嗽,喉痉挛,兴奋以及分泌物增加的发生率明显高于七氟醚组;两组吸入诱导对小儿的血压无明显的影响。结论:小儿使用高浓度七氟醚吸入诱导是较为理想的麻醉诱导方法之一,与异氟醚比较,其吸入诱导平稳,对气道的刺激性较小,诱导时间明显缩短。     

A comparison between single- and double-breath vital capacity inhalation induction with 8% sevoflurane in children

BACKGROUND: This study was conducted to determine if a double-breath (DB) vital capacity (VC) rapid inhalation induction using immediate high-inspired concentration of sevoflurane is as well tolerated as a single-breath (SB) technique and if it results in a shorter induction time. METHODS: A total of 104 children, ASA I-II, 6 year and above, undergoing elective surgery were randomly assigned to two groups: SB VC inhalation induction or DB VC inhalation induction with 8% sevoflurane in 66% nitrous oxide. The induction time, complications (cough, laryngospasm, breath-hold, movement, salivation) and level of satisfaction were documented. RESULTS: Induction was significantly faster in the DB group (41 +/- 9 s) compared with the SB group (50 +/- 14 s). DB inhalation induction was associated with fewer complications (15.4%) than the SB technique (50%). CONCLUSIONS: Double-breath VC inhalation induction with 8% sevoflurane is as well tolerated as a SB technique and results in a faster onset of anaesthesia.     

Vital capacity induction with 8% sevoflurane and N2O causes cerebral hyperemia

Purpose. Little is known about the influence of high-dose sevoflurane on cerebral volume. We evaluated induction time and cerebral blood volume with 8% sevoflurane using the “vital capacity induction” technique. Methods. Thirty-four patients were randomly allocated into three groups. Group P received 2.0 mg·kg⁻¹ of propofol i.v. and inhalation of 67% N₂O/O₂, whereas group S5 and group S8 received inhalation of primed 5% and 8% sevoflurane in 67% N₂O/O₂, respectively. Induction time was measured as the time from the start of inhalation, or from the end of injection, until loss of eyelash reflex. Near-infrared spectroscopy and bispectral index (BIS) were monitored continuously until 3 min after tracheal intubation. Results. Induction time was less in group S8 (17.3 ± 6.4 s, mean ± SD) than in groups P (25.7 ± 8.2 s) and S5 (33.0 ± 16.8 s). There was a significant increase in cerebral blood volume after intubation in group S8, as suggested by higher cerebral oxyhemoglobin and total hemoglobin levels. There were no differences in BIS scores among the groups during the study period. Conclusion. Vital capacity inhalation of 8% sevoflurane produces a faster loss of eyelash reflex than does 5% sevoflurane or propofol, but increases cerebral blood volume. Received: May 20, 2002 / Accepted: August 27, 2002 Address correspondence to: K. Iwasaki     

Hemodynamic response to tracheal intubation after vital capacity rapid inhalation induction (VCRII) with different concentrations of sevoflurane

STUDY OBJECTIVE: To evaluate the blood pressure (BP) and heart rate (HR) response to tracheal intubation after vital capacity rapid inhalation induction (VCRII) with four concentrations of sevoflurane followed by nitrous oxide (N2O) 50% and sevoflurane in concentrations administered by clinical judgment. DESIGN: Prospective, randomized study. SETTING: University teaching hospital. PATIENTS: 60 unpremedicated, ASA physical status I and II adult patients undergoing surgery with general anesthesia. INTERVENTIONS: After fentanyl 3 micrograms/kg, VCRII was accomplished with four concentrations of sevoflurane in O2: Group 1 (n = 15): sevoflurane 3%; Group 2 (n = 15): sevoflurane 4%; Group 3 (n = 15): sevoflurane 5%; and Group 4 (n = 15): sevoflurane 6%. At loss of consciousness, rocuronium 0.6 mg/kg was given, and intubation was performed 90 seconds later. Thereafter, anesthesia continued with N2O 50% and sevoflurane. MEASUREMENTS AND MAIN RESULTS: BP and HR measurements were made at the ward (baseline), at loss of consciousness, and just prior to, and each minute after, tracheal intubation during a 5-minute period. The hemodynamic profile among groups was similar, with a slight hypertensive and tachycardic response to intubation. CONCLUSION: VCRII with sevoflurane 3% to 6% following fentanyl 3 micrograms/kg can be considered for blunting the hemodynamic response to tracheal intubation in healthy patients.     

Comparison of single-breath vital capacity rapid inhalation with sevoflurane 5% and propofol induction on QT interval and haemodynamics for laparoscopic surgery

BACKGROUND AND OBJECTIVE: To compare two techniques to achieve induction of anaesthesia for laparoscopic surgery. A single-breath vital capacity rapid inhalation induction with sevoflurane was compared to intravenous propofol. Their effects on haemodynamics and the QT interval of the electrocardiogram were assessed. METHODS: Forty-four ASA I-II patients scheduled to undergo elective laparoscopic gynaecological surgery were divided into two groups. In the sevoflurane group (Group S, n = 22), general anaesthesia was induced with a single-breath vital capacity rapid inhalation of sevoflurane 5% with nitrous oxide (N2O) 65% in O2 and then anaesthesia was maintained with sevoflurane 1-1.5% with N2O 65% in O2. In the propofol group (Group P, n = 22), general anaesthesia was induced with propofol 2 mg kg(-1) intravenously and maintained with propofol 6 mg kg(-1) h(-1). Systolic, diastolic and mean arterial pressures, heart rate and end-tidal CO2 values were recorded before anaesthesia (basic value), during the induction period (time X), at 10 min (time Y) and at 30 min (time Z) of CO2 insufflation in all patients. QT intervals were calculated using Bazett's equation. RESULTS: Systolic, diastolic and mean arterial pressure values during the induction period (time X) were lower than the basic value in both groups (P < 0.05). In Group S, QTc intervals were significantly longer during the induction period (time X) and at the tenth min of CO2 insufflation (time Y) than Group P (P < 0.05). Five patients at time X and two patients at time Y developed ventricular dysrhythmias, which improved spontaneously in Group S. In Group P, there was no significant difference in QTc intervals and only one patient developed a ventricular dysrhythmia at time Y. CONCLUSIONS: Single-breath vital capacity rapid inhalation induction technique with sevoflurane can cause prolongation of the QT interval and dysrhythmias, compared with induction and maintenance of anaesthesia with propofol in laparoscopic surgery.     

Airway irritation produced by volatile anaesthetics during brief inhalation: comparison of halothane,enflurane, isoflurane and sevoflurane

Eleven male volunteers were studied to compare the airway irritation produced by the four anaesthetic agents: halothane, enflurane, isoflurane and sevoflurane at two concentrations, equivalent to one and two MAC. Tidal volume, respiratory frequency and functional residual capacity changes induced by 15 sec inhalation of the anaesthetics were measured using respiratory inductive plethysmograph. Appearance of the cough reflex was also observed. The order of subjective airway irritation was evaluated by the volunteers. Inhalation of the anaesthetic agents induced a decrease in tidal volume, increase in respiratory frequency and decrease in functional residual capacity. Significant changes were considered to have occurred if tidal volume and respiratory frequency changed by more than 30% from the resting values for at least ten seconds, or if functional residual capacity changed by more than 30% of the value at resting tidal volume, for at least ten seconds. Each change was induced most frequently by isoflurane followed by enflurane, halothane and, least frequently, by sevoflurane. The orders of appearance of the cough reflex and of subjective airway irritation were similar. Sevoflurane did not elicit a cough reflex. It is concluded that sevoflurane was the least irritant anaesthetic and is considered to be the most suitable for inhalational induction of anaesthesia. Sept volontaires du sexe masculin font partie dune étude visant à comparer les ejfets irritants de quatre agents anesthésiques sur les voies respiratoires: l’halothane, l’enflurane, l’ isoflurane et le sévoflurane, à deux concentration qui équivalent soit à MAC 1, soit à MAC 2. On mesure les changements de volume courant, de fréquence respiratoire et de capacité résiduelle fonctionnelle à l’aide d’un pléthysmographie à induction. On note l’apparition du réflexe de toux. De plus, on évalue le degré subjectif d’irritation éprouvé par les sujets. L’inhalation d’agents anesthésiques cause une baisse du volume courant, une augmentation de la fréquence respiratoire et une diminution de la capacité résiduelle fonctionnelle. On considère significatifs les changements de volume courant et de fréquence respiratoire de plus de 30% des valeurs de repos pour au moins dix secondes, les changements de capacité résiduelle fonctionnelle de plus de 30% de sa valeur au volume courant de repos pour au moins dix secondes. Les changements sont initiés principalement par l’isoflurane, suivi par l’enflurane, l’halothane et moins fréquemment par le sévoflurane. L’ordre d’apparition du réflexe de toux et de l’impression subjective d’irritation des voies aériennes est identique. Le sévoflurane ne provoque pas de réflexe de toux. On conclut que le sévoflurane est le moins irritant des anesthesiques et qu’on peut le considerer comme celui qui convient le mieux à l’induction de l’anesthésie par inhalation.     

A case report of rapid inhalation induction with sevoflurane in a patient with porphyria

We experienced anesthetic management for a patient with acute intermittent porphyria. A 52-year-old woman underwent a partial right mastectomy. She was anesthetized with continuous thoracic epidural blockade combined with general anesthesia using nitrous oxide, oxygen and sevoflurane. To avoid porphyric attack, we chose vital capacity breath technique for rapid induction. We could successfully manage the patient during the perioperative period without appearance of porphyric symptoms. We conclude that vital capacity breath technique for rapid induction may be suitable for use in patients with porphyria.     

A comparison of 8% and 12% sevoflurane for inhalation induction in adults

Sevoflurane is a non-pungent volatile anaesthetic agent with a low blood-gas solubility coefficient. It has been studied in concentrations of up to 8% for induction of anaesthesia. Previous work has suggested that there may be a ceiling effect with increasing concentration of sevoflurane above 6%, but there are no published studies using 12% sevoflurane. This study compared 8 and 12% sevoflurane to induce anaesthesia in adults. Sevoflurane was administered using two adapted datum vaporisers with the interlock removed. Induction with 12% sevoflurane compared to 8% sevoflurane produced a significant decrease in the time to achieve central pupils, corresponding to surgical anaesthesia and the third part of Guedel's stage 3 of anaesthesia (mean time (SD) 201 s (81) and 247 s (39), respectively, p < 0.05). Twelve-percent sevoflurane produced a similar stable cardiovascular profile to 8% sevoflurane, and there was no increase in respiratory complications.