Vital Capacity Rapid Inhalation Induction Research Articles

Minimal alveolar concentration of sevoflurane in combination with remimazolam in adults during laryngeal mask insertion: an up-down sequential allocation study

BackgroundRemimazolam is a novel ultrashort-acting intravenous benzodiazepine sedative-hypnotic. The combination of remimazolam and sevoflurane does not increase respiratory sensitivity, produce bronchospasm, or cause other adverse conditions. We aimed to observe the effects of different remimazolam doses on the minimum alveolar concentration (MAC) of sevoflurane at end-expiration during laryngeal mask insertion and evaluate the effect of sex on the efficacy of the combination of remimazolam on the suppression of laryngeal mask insertion in adult patients.MethodsWe included 240 patients undergoing laparoscopic surgery under general anesthesia with elective placement of a laryngeal mask (120 males and 120 females). The patients were randomly divided into four groups according to sex: a control group (randomization for female patients, RF0; randomization for male patients, RM0) and three remimazolam groups (RF1, RM1 / RM2, RF2 / RM3, RF3), with 30 patients in each group. Induction was established by vital capacity rapid inhalation induction (VCRII), using 8% sevoflurane and 100% oxygen (6 L/min) in all patients. The (RF1, RM1), (RM2, RF2), and (RM3, RF3) groups were continuously injected with remimazolam at doses of 1, 1.5, and 2.0 mg/kg/h, respectively, while the (RM0, RF0) group was injected with an equal volume of normal saline. The end-expiratory concentration of sevoflurane was adjusted to a preset value after the patient’s eyelash reflex disappeared. After the end-expiratory concentration of sevoflurane was kept stable for at least 15 min, the laryngeal mask was placed, and the patient’s physical response to the mask placement was observed immediately and within 30 s of placement. The MAC of sevoflurane was measured using the up-and-down sequential method of Dixon.ResultsThe calculated MAC of end-expiratory sevoflurane during laryngeal mask insertion in adult females was (2.94 ± 0.18)%, (2.69 ± 0.16)%, (2.32 ± 0.16)% and (1.83 ± 0.15)% in groups RF0, RF1, RF2 and RF3; (2.98 ± 0.18)%, (2.80 ± 0.19)%, (2.54 ± 0.15)% and (2.15 ± 0.15)% in male groups RM0, RM1, RM2 and RM3, respectively. The MAC values were significantly lower in the (RF1-RF3, RM1-RM3) group when compared to the (RF0, RM0) group. There was no significant difference between (RF0, RF1) and (RM0, RM1), but the MAC value of the RF2-RF3 group was significantly lower than that of the RM2-RM3 group.ConclusionsRemimazolam can effectively reduce end-expiratory sevoflurane MAC values during laryngeal mask placement in adults. When remimazolam was measured above 1.5 mg/kg/h, the effect of inhibiting laryngeal mask implantation in female patients was stronger than that in male patients. Remimazolam at a dose of 1–2 mg/kg/h combined with sevoflurane induction can be safely and effectively used in these patients.

Comparison of vital capacity rapid inhalation and tidal ventilation induction with sevoflurane in adults: a prospective cohort study.

Vital capacity rapid inhalation induction (VCRII) results in faster achievement of desired minimum alveolar concentration while reducing the incidence of excitatory phenomenon compared to conventional incremental technique. This study aimed to determine whether the VCRII can achieve faster induction of anesthesia in adults compared to the traditional tidal ventilation (TV) technique. Following the approval from the Institutional Ethics Committee, Amala Institute of Medical Sciences, with an approval No. AIMSIEC/07/2017, on July 1, 2017, 51 adults belonging to American Society of Anesthesiologists physical status I–II, undergoing elective surgery at a tertiary care teaching hospital were prospectively assigned to two groups: 25 in VCRII (38.3 ± 13.3 years old, 20 (80%) females) and 26 in TV inhalation induction (35.2 ± 11.9 years old, 17 (65%) females) using 8% sevoflurane in 66% nitrous oxide. The induction time, such as time (in seconds) to the cessation of voluntary finger tapping, time to loss of eyelash reflex, time to return of regular breathing, the return of conjugate gaze, was measured. The primary outcome was time to induction as defined by time to loss of eyelash reflex. Hemodynamic effects of both methods were compared at baseline and 1, 3, 5, 10, 15-minute intervals from induction. Induction was significantly faster in the VCRII group compared with the TV group in all the measured parameters. Hemodynamic parameters were comparable in both the groups. VCRII resulted in a faster induction time compared to the TV technique in adults.

Intravenous landiolol, a novel β 1-adrenergic blocker, reduces the minimum alveolar concentration of sevoflurane in women

Study Objective To investigate the effect of intravenous (IV) landiolol, a novel β 1-adrenergic blocker, on the minimum alveolar concentration (MAC) of sevoflurane in adult women. Design Prospective, randomized study. Setting University hospital. Patients 42 ASA physical status 1 and 2 women, aged 24-57 years, who were scheduled to undergo elective abdominal surgery. Interventions Anesthesia was induced in all patients by vital capacity rapid inhalation induction of sevoflurane. In the landiolol group, administration of landiolol began when patients took a vital-capacity breath: 0.125 mg/kg/min for one minute and then 0.04 mg/kg/min. Normal saline was administered in the control group. Measurements MAC was determined by a technique adapted from the conventional up-down method. Main Results The MAC of sevoflurane was 2.2% ± 0.2% in the control group and 1.7% ± 0.2% in the landiolol group, a statistically significant difference ( P = 0.0005). Conclusions IV landiolol reduces the MAC of sevoflurane in women by approximately 20%.

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

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. 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. 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. 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.

The Effects of the Lidocaine or Fentanyl Pretreatment on Inhalational Induction with Sevoflurane

Background: Sevoflurane has been widely used for inhalation induction and intubation in children and adults. There are some reports about hemodynamic instability and respiratory effects during inhalation induction. We evaluated the effects of fentanyl, lidocaine, or both on inhalation induction and intubation using sevoflurane without neuromuscular blocking agents. Methods: Forty healthy adult female patients, 20 to 60 years old, premedicated with midazolam 3 mg were randomly received iv saline (Group A), lidocaine 1 mg/kg (Group B), fentanyl (Group C) or both lidocaine 1 mg/kg and fentanyl (Group D). Anesthesia was induced with 8% sevoflurane inhalation and intubation was done without muscle relaxant. A blind observer recorded the change of blood pressure, heart rate, BIS score, and the time needed for induction and intubation. Results: The mean times for BIS score below 40 were seconds and there were no significant difference among groups. The mean time for loss of self respiration and intubation in group A were significantly longer than those of other groups. The heart rates during induction and intubation of group A were significantly greater than those of other groups. There was no significant difference in blood pressure and side effects during intubation among groups. Conclusions: Pre-treatment with fentanyl or lidocaine makes smoother and faster induction and intubation during vital capacity rapid inhalation induction with sevoflurane.

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.

Rapid sevoflurane induction compared with thiopental

Study objectives To examine whether the speed of induction of anesthesia with sevoflurane/nitrous oxide (N 2O) utilizing a 10-second vital capacity rapid inhalation induction (VCRII) followed by tidal breathing was similar or faster than cautious intravenous (IV) thiopental induction with inhaled N 2O. Design Prospective, randomized, double-blinded study. Setting Veterans Affairs Medical Center. Patients 50 male ASA physical status I, II, and III patients scheduled for general anesthesia. Interventions Patients were randomized to receive either 8% sevoflurane or IV thiopental. Patients were allocated to one of two groups of 25 patients each. In both groups, the breathing circuit was initially primed for 5 minutes with (4 L/min) and O 2 (2 L/min), while the Y-piece was occluded. In the sevoflurane group, the circuit was additionally primed with 8% sevoflurane. Patients were trained to perform a vital capacity breath. After maximal exhalation, the occluding plug was rapidly removed from the Y-piece and connected to the facemask. The patient then inspired to vital capacity, held his breath for 10 seconds, and then was allowed to breathe normally. At the end of the 10-second breathhold, and as the patient started normal breathing, either thiopental (thiopental group) or normal saline (sevoflurane group) was injected at a rate of 4 mL every 10 seconds. Measurements A study-blinded observer recorded the time to induction, as defined by the time to loss of eyelash reflex, and noted the occurrence of side effects. Main results The speed of induction was the same for both groups ( p > 0.05). An average of eight breaths was required before loss of eyelash reflex. Side effects occurred in 36% of the patients in the thiopental group, and 32% in the sevoflurane group ( p > 0.05); these were minor and did not affect induction. Conclusion Sevoflurane/N 2O VCRII as used in this investigation is an effective inhalation technique; it resulted in an induction time similar to that of slow IV thiopental with inhaled N 2O.

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

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

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.

Intubating Conditions and Responses to intubation after Sevoflurane-N2O-O2 Vital Capacity Rapid inhalation induction without Muscle Relaxant:Comparison with Propofol-N2O-O2-Vecuronium

Background: The objective of this study was to investigate the conditions required for tracheal intubation and the responses to intubation after the administration of a high concentration of sevoflurane- for vital capacity rapid inhalation induction (VCRII) without muscle relaxant. We compared those with propofol--vecuronium induction. Methods: Fifty ASA physical status I or II adult patients without airway abnormalities who were scheduled for elective surgery requiring endotracheal intubation were randomly allocated to receive either propofol 6 g/ml target controlled infusion- 4 L/min- 2 L/min-vecuronium 0.12 mg/kg iv (group PV) or 8% sevoflurane- 4 L/min- 2 L/min without muscle relaxant (group SO). Vecuronium was injected ninety seconds after starting propofol infusion in group PV. Group SO patients were coached on how to perform vital capacity breathing and the breathing circuit was primed for 2 minutes. Five minutes after the administration of induction agents, intubation was attempted. Intubation conditions, arterial blood pressure (BP) and heart rate (HR) changes accompanying both induction techniques were monitored. Results: The time to loss of consciousness for group SO was significantly shorter (41.0 15.0 sec vs 81.8 25.8 sec, P = 0.000). Intubation was successful in 24 out of 25 patients (96%) in group PV and 25 out of 25 patients (100%) in group SO, and clinically acceptable intubating conditions were obtained in 23 of the 25 patients (92%) in group PV and 21 of the 25 patients (84%) in group SO. Significant decreases in BP from baseline were observed before intubation in both groups. The increase in BP at 1min after intubation was significantly greater in group PV. HR did not differ in the two groups. Conclusions: The intubation conditions after sevoflurane- without muscle relaxant were similar to those produced after propofol--vecuronium. Sevoflurane- VCRII is a useful alternative technique for tracheal intubation when muscle relaxant should be avoided.

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 μg/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 μg/kg can be considered for blunting the hemodynamic response to tracheal intubation in healthy patients.

Efficient inspired concentration of sevoflurane for vital capacity rapid inhalation induction (VCRII) technique

Efficient inspired concentration of sevoflurane for vital capacity rapid inhalation induction (VCRII) technique

Efficient inspired concentration of sevoflurane for vital capacity rapid inhalation induction (VCRII) technique

Study Objectives: To evaluate the efficient inspired concentration of sevoflurane for a vital capacity rapid inhalation induction (VCRII) technique with respect to induction time, characteristics, and acceptability. Design: Prospective study. Setting: Medical college hospital. Patients: 68 unpremedicated healthy adult volunteers were assigned to one of four groups in order of sequential entry of informed consent. Interventions: 3%, 4.5%, 6%, or 7.5% concentrations of sevoflurane were administered for 5 minutes (3% and 4.5%) or 3 minutes (6% and 7.5%) using a single breath technique. Measurements and Main Results: The mean induction time required with 3%, 4.5%, 6%, or 7.5% sevoflurane was 120 ± 26 sec, 79 ± 18 sec, 52 ± 15 sec, or 47 ±17 seconds, respectively. Each induction time was significantly different from the others ( p < 0.05) except for that between 6% and 7.5%. There appeared to be a direct inverse relationship between the mean induction time and the logarithm of inspired concentration of sevoflurane, but this relationship did not extend beyond concentrations above 6%. Blood pressure decreased by approximately 18% from baseline at the end of inhalation of the drug, and heart rate remained constant in all groups. Except of one subject in the 7.5% group, no coughing was observed and laryngospasm, breathholding, and secretions were not seen in any subjects. Slight limb movement was observed in a few subjects in each group. All subjects except one in the 3% group would accept undergoing a similar procedure again. Conclusion: Sevoflurane 6% can be recommended for VCRII, but increasing the concentration higher than this does not markedly shorten the induction time and thus seems to add little benefit.

The influence of additional nitrous oxide during rapid anesthetic induction with sevoflurane.

In this study, a vital capacity rapid inhalation induction technique was used, and 4.5% sevoflurane in 100% oxygen and with 66% nitrous oxide in oxygen were compared. Each anesthetic gas was used on a group of 17 unpre-medicated volunteers. The induction time of sevoflurane in nitrous oxide with oxygen and sevoflurane in oxygen were 55±10 s and 81±22 s (SD), respectively, (P<0.05). Notable cardiovascular instability was not observed in either group. Serious complications such as laryngospasm, breath holding, and excessive salivation were not observed in either group. In conclusion, the addition of nitrous oxide to sevoflurane in oxygen is a useful technique because there were no increases in complications during the accelerated rapidity of induction.

Induction of Anesthesia with Sevoflurane, Nitrous Oxide, and Oxygen

In this study, the vital capacity rapid inhalation induction of anesthesia (VCRII) technique and the conventional spontaneous inhalation induction technique, each using 4.5% sevoflurane in nitrous oxide and oxygen, were compared. The VSRII group (n = 32) and conventional group (n = 32) were each tested on unpremedicated volunteers. VCRII required only half the time of conventional inhalation induction (54 s and 108 s, respectively), and was not associated with cardiovascular instability. Each of the two techniques was found acceptable by most of the volunteers studied (more than 80%). However, sevoflurane is best used with the VCRII technique because VCRII resulted in fewer excitement movements that could lead to severe complications and pronounced excitement.