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.     

Rapid induction with 7% sevoflurane inhalation—not the single-breath method

The usefulness of the rapid anesthesia induction method with 7% sevoflurane, not the single-breath method, was investigated in 88 patients with ASA physical status 1. Anesthesia was induced with 3 l·min⁻¹ nitrous oxide in 3 l·min⁻¹ oxygen and sevoflurane 7% for 3 min (group A), 7% for 5 min (group B), 7% for 7 min (group C), and 5% for 7 min in conventional induction (group D). There were 22 patients in each group. Each sevoflurane concentration was given at the same time as the start of nitrous oxide inhalation except for group D. The changes in blood pressure and heart rate were the smallest in group A. The time for the loss of consciousness was shorter in groups A (47.2 s), B (44.9 s), and C (49.8 s) than in group D (73.4 s). During induction, body movements were seen in 18.2% in group A and 13.6% in the other 3 groups, but no other complications such as coughing, breath holding, or laryngospasm were seen in any group. In conclusion, the anesthesia induction method with 3 min of 7% sevoflurane inhalation was useful for rapid induction.     

Comparison of vital capacity induction with sevoflurane to intravenous induction with propofol for adult ambulatory anesthesia.

We compared vital capacity inhaled induction (VC) with sevoflurane with i.v. induction with propofol for adult ambulatory anesthesia. Patients were randomly assigned to receive either 8% sevoflurane in 75% N2O/O2 from a primed circuit (VC, 32 patients) or propofol 2-mg/kg bolus (i.v., 24 patients). Times to loss of consciousness (response to command) and induction side effects (airway, hemodynamic, motor) were assessed. Anesthesia was maintained with sevoflurane/N2O via a face mask for both groups. At the end of surgery, recovery times were measured and psychomotor function tests were performed. Patients were also asked to assess the quality of their anesthesia. Of the VC patients, 59% lost responsiveness in one breath, taking 39 +/- 3 s. All VC patients completed the induction, and all measures of induction time were significantly shorter for VC than for i.v. Induction side effects were different in the two groups (cough and hiccough for VC versus movement and blood pressure changes for i.v.), but overall incidences were similar. There were no significant differences in any index of early or intermediate recovery. Mild nausea occurred more often with VC, but no antiemetics were needed, and discharge was not delayed. Patients' assessments of the quality of induction or wake up were not significantly different between VC and i.v. Thus, VC induction with sevoflurane is an acceptable alternative to propofol i.v. induction of general anesthesia for adult ambulatory surgical patients. IMPLICATIONS: A vital capacity induction with sevoflurane produced a faster loss of consciousness and had side effects, recovery times, and patient satisfaction similar to that of a propofol induction in adults undergoing ambulatory surgery.     

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.     

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.     

Multiple-deep-breath inhalation induction with 5% sevoflurane and 67% nitrous oxide: comparison with intravenous injection of propofol

Purpose. To evaluate the clinical characteristics of multiple-deep-breath inhalation induction with sevoflurane and nitrous oxide followed by the same inhalational anesthetics for maintenance, we compared the technique with intravenous propofol anesthesia. Methods. Forty patients scheduled for ophthalmic surgery under general anesthesia with a laryngeal mask airway (LMA) were assigned to two groups. Anesthesia was induced with multiple-deep-breath inhalation of 5% sevoflurane and 67% nitrous oxide in oxygen (group S: n = 20) or intravenous injection of 1% propofol at the rate of 1200 ml·h⁻¹ with spontaneous inhalation of 67% nitrous oxide in oxygen until the patient lost consciousness or received propofol up to 2 mg·kg⁻¹ (group P: n = 20). We attempted to insert an LMA when the patient's jaw relaxation was adequate. We compared induction times, recovery times, occurrence of adverse events, and patient satisfaction between the two groups. Results. The mean time to insertion of the LMA was significantly shorter in group P (209 ± 118 s) than in group S (302 ± 102 s; P < 0.05). The recovery times did not differ significantly between the groups. There were no serious side effects during the induction and recovery period in either group. Significantly more patients in group P than in group S wanted to have the same anesthetic method (90% vs 50%; P < 0.05). Conclusion. Multiple-deep-breath inhalation induction with 5% sevoflurane and 67% nitrous oxide followed by the same inhalational anesthetics for maintenance was safely performed without serious adverse events. However, the induction time was shorter and patient satisfaction was higher in propofol group than in the inhalational group. Received: April 11, 2001 / Accepted: November 6, 2001     

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).      

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。     

Effects of sevoflurane versus propofol on QT interval.

BACKGROUND: Prolongation of the QT interval is an alteration of the electrocardiogram (ECG) that may result in a potentially dangerous polymorphic ventricular tachycardia known as torsade de pointes. Michaloudis et al. investigated the effect of isoflurane and halothane on the QT interval in premedicated and non premedicated children, and in premedicated adults. Isoflurane significantly prolonged the QTc interval, in contrast to halothane, which shortened the QTc interval. The aim of the study was to evaluate the effect of sevoflurane on the QT interval in patients undergoing non-cardiac surgery. METHODS: One hundred and eighty patients classified as ASA physical status I-III were enrolled and 102 were excluded. Patients had been scheduled for elective non cardiac surgery. Exclusions criteria were: cardiovascular impairment or chronic obstructive lung disease, medication affecting QT interval, and an abnormal prolongation of the QTc interval (440 ms). The patients were then randomly allocated to one of two groups, one receiving sevoflurane anesthesia and the other receiving propofol anesthesia. In all patients, a 12 lead ECG was recorded before surgery, after intubation, after extubation. The investigators reading the ECG were blinded to the type of induction and anesthesia used. The following variables were recorded or calculated: heart rate, P-R interval, QRS interval, QT interval, QTc interval according to Bazett's formula, systolic, diastolic and mean blood pressure. RESULTS: The sevoflurane significantly prolongs the QT and the QTc interval, whereas the induction and total intravenous anesthesia with propofol significantly shortens the QT but not the QTc interval. CONCLUSIONS: The amount the sevoflurane-associated QT prolongation may possibly be of clinical significance in some patients presenting long QT syndrome, hypokalemia, or in presence of other agents or factors that lengthen QT.     

Recovery characteristics using single-breath 8% sevoflurane or propofol for induction of anaesthesia in day-case arthroscopy patients

We studied the induction and recovery characteristics following inhalational induction with 8% sevoflurane in nitrous oxide and oxygen compared with intravenous propofol in 40 patients presenting for arthroscopy of the knee. Patients were randomly allocated to receive either induction agent, and anaesthesia was then maintained with sevoflurane in oxygen and nitrous oxide. A computerised test of hand--eye co-ordination and a p-deletion test were used to measure psychomotor recovery. The sevoflurane group had a faster onset of anaesthesia time. No significant differences between the groups were found in time to eye opening or psychomotor tests. Nausea and vomiting scores were significantly higher at 30 min in the sevoflurane group (p = 0.04); this difference was no longer significant by 90 min. We conclude that inhalational induction with sevoflurane in these patients has no important clinical advantages and causes more nausea and vomiting than propofol.     

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.     

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.      

Vital capacity rapid inhalation induction technique: comparison of sevoflurane and halothane

Induction of anaesthesia using the vital capacity rapid inhalation induction (VCRII) technique with either sevoflurane or halothane was compared. The induction time, characteristics, and acceptability were assessed. Thirty-two volunteers were given one of the vapours: 17 received sevoflurane and 15 halothane. Subjects were unpremedicated and breathed approximately 2.6 × minimum alveolar concentration (MAC) equivalent of either agent. There were no differences in the patients’ cardiovascular or respiratory variables. The mean time for induction of anaesthesia with halothane (153 ± 46 sec, SD) was slower than with sevoflurane (81 ± 22 sec, SD, P < 0.05), reflecting its higher blood:gas solubility. There were fewer induction complications such as coughing and movement in the sevoflurane than in the halothane group. Subjects in the sevoflurane group found the smell of anaesthetic more acceptable than those in the halothane group (65% vs 13%, respectively). Subjects in both groups had no objection to undergoing the procedure again. It is concluded that both halothane and sevoflurane are effective in VCRII of anaesthesia without premedication. However, the slower speed of induction with halothane frustrated the anaesthetist because of the longer induction time, and may increase the chance of pronounced excitatory phenomena occurring.     

Comparative study of inhalation induction by vital capacity breath in adults using 6% sevoflurane with oxygen or 4.5%sevoflurane in 50% nitrous oxide

OBJECTIVE: To evaluate the efficacy, side effects and hemodynamic characteristics of induction by vital capacity breath in adults using 6% sevoflurane and oxygen versus 4.5% sevoflurane and 50% nitrous oxide. PATIENTS AND METHODS: We assigned 50 ASA I-II patients aged 20 to 70 years old randomly to two groups of 25 to receive either 6% sevoflurane in oxygen or 4.5% sevoflurane in nitrous oxide. All patients were premedicated with oral bromazepam (1.5 to 3 mg). Induction was by vital capacity breath using a Mapleson A circuit (8 l. min-1) for 5 min. We recorded induction time, side effects, hemodynamic variables and patient opinion after surgery. RESULTS: Induction time was significantly faster for the sevoflurane-oxygen group (60 +/- 10 s) than for the sevoflurane-nitrous oxide group (71 +/- 8 s) (p < 0.001). Complications were minor and hemodynamic variables stable in both groups, with no statistically significant differences. The patients expressed satisfaction with both induction techniques. CONCLUSIONS: A vital capacity breath of 6% sevoflurane provided rapid induction. Induction was no more rapid when 50% nitrous oxide was added and the incidence of side effects did not decrease. Hemodynamic variables are stable during induction with sevoflurane with or without nitrous oxide, making this a well-tolerated alternative technique that is positively evaluated by patients.     

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.     

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.