Minimum alveolar concentration of sevoflurane for laryngeal mask airway removal in anesthetized children

Safety of removal of ProSeal laryngeal mask airway in children in the supine versus lateral position in a deep plane of anesthesia: A randomized controlled trial

Importance

When a ProSeal laryngeal mask airway (PLMA) is removed with the child in a deep plane of anesthesia, the upper airway muscle tone and protective upper airway reflexes may be obtunded.

Objective

To determine whether the supine or lateral position is safer for the removal of a PLMA in deeply anesthetized children by comparing the incidence of upper airway complications.

Methods

This randomized single-blind comparative trial was conducted at a tertiary care hospital between January 2020 and September 2020. Forty children of the American Society of Anesthesiologists class I/II of ages 1-12 years age undergoing surgery under general anesthesia with PLMA used as the definitive airway device were recruited. Patients were randomly allocated to lateral group or supine group for PLMA removal in a deep plane of anesthesia in the lateral or supine position. The primary outcome was the number of patients experiencing one or more upper airway complications and the secondary outcomes were incidence of individual respiratory adverse effects and of severe airway complications.

Results

The incidence of airway complications was 30% in the supine group and 20% in the lateral group (P = 0.6641). Incidence of laryngospasm, immediate stridor, and excessive secretions were similar. Early stridor and oxygen desaturation were higher in the supine group (P = 0.0374, P = 0.0183 respectively).

Interpretation

The overall incidence of upper airway complications was similar with the removal of a PLMA in the supine or lateral position in deeply anesthetized children. The incidence of oxygen desaturation and stridor were higher with PLMA removal in the supine as compared to the lateral position.

Optimum time of LMA ProSeal removal in adult patients undergoing isoflurane anesthesia: A randomized controlled trial

Background and Aims:

Optimum timing of laryngeal mask airway (LMA) removal after general anesthesia with isoflurane is debatable. The objective was to investigate the potential benefits of removing LMA ProSeal at ≤0.4 Minimum alveolar concentration (MAC) isoflurane over awake and “deep plane” extubation after short duration laparoscopic gynecological surgery.

Material and Methods:

In this prospective randomized trial 90 adult female patients undergoing elective laparoscopic surgery under general anesthesia using LMA ProSeal™ as airway device were included. At the end of surgery, LMA ProSeal™ was removed when the patient was awake, could open mouth following verbal command (Group A); at MAC ≤0.4 (Group B); or at MAC of 0.6 (Group C). Adverse airway events like nausea, vomiting, airway obstruction, coughing, bucking, laryngospasm were noted. Statistical analyses were done by SPSS statistical software (IBM SPSS Statistics for Mac OS X, Version 21.0. IBM Corp, Armonk, NY).

Results:

Baseline demographic characteristics were comparable in all three groups. Coughing or bucking at the time of LMA removal was higher in group A (P = 0.004). Snoring and airway obstruction after LMA removal was significantly higher in group C compared to group A and group B (P = 0.002 and P = 0.011, respectively). There was significant change in mean arterial pressure and heart rate between before and after LMA removal on group A (P = 0.008 and P < 0.001, respectively) but not in other groups.

Conclusion:

MAC ≤0.4 can be considered optimum depth of anesthesia for removal of LMA Proseal in adult patients undergoing isoflurane anesthesia.

The impact of topical lidocaine and timing of LMA removal on the incidence of airway events during the recovery period in children: a randomized controlled trial

Background

The timing of laryngeal mask airway (LMA) removal remains undefined. This study aimed to assess the optimal timing for LMA removal and whether topical anesthesia with lidocaine could reduce airway adverse events.

Methods

This randomized controlled trial assessed one-to-six-year-old children with ASA I-II scheduled for squint correction surgery under general anesthesia. The children were randomized into the LA (lidocaine cream smeared to the cuff of the LMA before insertion, with mask removal in the awake state), LD (lidocaine application and LMA removal under deep anesthesia), NLA (hydrosoluble lubricant application and LMA removal in the awake state) and NLD (hydrosoluble lubricant application and LMA removal in deep anesthesia) groups. The primary endpoint was a composite of irritating cough, laryngeal spasm, SpO₂ < 96%, and glossocoma in the recovery period in the PACU. The secondary endpoints included the incidence of pharyngalgia and hoarseness within 24 h after the operation, duration of PACU stay, and incidence of agitation in the recovery period. The assessor was unblinded.

Results

Each group included 98 children. The overall incidence of adverse airway events was significantly lower in the LA group (9.4%) compared with the LD (23.7%), NLA (32.6%), and NLD (28.7%) groups (P=0.001). Cough and laryngeal spasm rates were significantly higher in the NLA group (20.0 and 9.5%, respectively) than the LA (5.2 and 0%, respectively), LD (4.1 and 1.0%, respectively), and NLD (9.6 and 2.1%, respectively) groups (P=0.001). Glossocoma incidence was significantly lower in the LA and NLA groups (0%) than in the LD (19.6%) and NLD (20.2%) groups (P< 0.001). At 24 h post-operation, pharyngalgia incidence was significantly higher in the NLA group (15.8%) than the LA (3.1%), LD (1.0%), and NLD (3.2%) groups (P< 0.001).

Conclusions

LMA removal in the awake state after topical lidocaine anesthesia reduces the incidence of postoperative airway events.

Trial registration

ChiCTR, ChiCTR-IPR-17012347. Registered August 12, 2017.

Prospective, Randomized Comparison of the i-gel and the Self-Pressurized air-Q Intubating Laryngeal Airway in Elderly Anesthetized Patients

BACKGROUND

Age-related changes in upper airway anatomy may affect the overall performance of supraglottic airways significantly. The clinical performance of the i-gel and the self-pressurized air-Q intubating laryngeal airways with noninflatable cuffs for elderly populations remains unknown, unlike in children. Thus, we performed a prospective, randomized comparison of these 2 supraglottic airways in elderly patients undergoing general anesthesia.

METHODS

We recruited 100 patients, 65-90 years of age, who were scheduled for elective surgery under general anesthesia with muscle relaxation. The enrolled patients were allocated to the i-gel or self-pressurized air-Q group. We assessed oropharyngeal leak pressure as the primary outcome and fiberoptic view after placement and fixation of the airway and at 10 minutes after the initial assessment. The fiberoptic view was scored using a 5-point scale as follows: vocal cords not visible; vocal cords and anterior epiglottis visible, >50% visual obstruction of epiglottis to vocal cords; vocal cords and anterior epiglottis visible, <50% visual obstruction of epiglottis to vocal cords; vocal cords and posterior epiglottis visible; and vocal cords visible. We also investigated success rate and ease of insertion, insertion time, and manipulations during insertion as insertion variables, complications during maintenance and emergence periods, and postoperative pharyngolaryngeal complications including sore throat, dysphagia, and dysphonia.

RESULTS

After assessing for eligibility, 48 patients were allocated to each group. Oropharyngeal leak pressures were significantly higher in the i-gel group than in the self-pressurized air-Q group (P < .001) at the 2 measurement points. The raw mean difference at initial assessment and the median difference after 10 minutes were 5.5 cm H2O (95% confidence interval, 3.3-7.6 cm H2O) and 5.0 (95% confidence interval, 2.0-7.0 cm H2O), respectively. The initial scores of fiberoptic view were similar in the 2 groups. However, the self-pressurized air-Q supraglottic airway provided a significantly improved fiberoptic view at 10 minutes after initial assessment (P = .030). We found no statistically significant differences in insertion variables and complications between the 2 groups.

CONCLUSIONS

The i-gel provided better sealing function than the self-pressurized air-Q supraglottic airway according to the high oropharyngeal leak pressures in elderly patients during general anesthesia. The self-pressurized air-Q supraglottic airway had improved fiberoptic views in elderly patients during general anesthesia.

ED50 of sevoflurane for I-Gel removal in anesthetized children in cataract surgeries using subtenon block

OBJECTIVE

The aim of this study was to determine the minimum concentration of sevoflurane required for I-Gel removal in 50% children undergoing elective cataract surgery.

DESIGN

A prospective observational study.

SETTING

A single tertiary care surgical center.

MATERIALS AND METHODS

Our study enrolled 20 American Society of Anesthesiologists I and II children aged 2-10 years, undergoing elective cataract surgery. Anesthesia was induced with sevoflurane and oxygen/nitrous oxide mixture and a size 2 I-Gel was inserted. A subtenon block was administered in all children before surgical incision. Sevoflurane was used for maintenance of anesthesia. Predetermined end-tidal concentration of sevoflurane was maintained for 10 min at the end of surgery before I-Gel removal was attempted. End-tidal concentrations were increased/decreased using the Dixon up-down method (with 0.2% as a step size) in the next patient depending on the previous patient's response. Patient responses to I-Gel removal were classified as "movement" or no "movement".

RESULTS

Minimum concentration of sevoflurane required for successful removal of a I-Gel in 50% (ED50) and 95% (ED95) of children was 0.44% (95% confidence interval [CI], 0.34-0.52%) and 0.77% (95% CI, 0.63-1.2%), respectively.

CONCLUSION

A very low end-tidal concentration of sevoflurane (ED50 of 0.44% ED95 of 0.77%) is required for I-Gel removal in children in cataract surgery with the supplementation of subtenon block.

Effects of changing from sevoflurane to desflurane on the recovery profile after sevoflurane induction: a randomized controlled study

PURPOSE

Desflurane has the lowest solubility of currently available volatile anesthetics and may allow for more rapid emergence and recovery compared with sevoflurane. Nevertheless, after volatile induction with sevoflurane, it has not been determined whether the use of desflurane provides faster emergence and recovery. The present study aimed to elucidate the effects of changing from sevoflurane to desflurane during the early part of anesthesia.

METHODS

Fifty-two patients who were scheduled for vitreous surgery with general anesthesia were enrolled in this randomized controlled study. Anesthesia was induced with volatile induction consisting of 100% oxygen (6 L·min(-1)) and 5% sevoflurane. For anesthesia maintenance, patients were randomized to receive 1-2% sevoflurane or 3-6% desflurane. In the desflurane group, the anesthetic agent was changed from sevoflurane to desflurane within five minutes following endotracheal intubation. After surgery, we assessed the following endpoints: the times from discontinuing volatile anesthetics to eye opening, obeying the command to squeeze the investigator's hand, tracheal extubation, and orientation to the patients' full name, date, and place.

RESULTS

Emergence and recovery were significantly faster in the desflurane group than in the sevoflurane group in times to mean (SD) eye opening [6.5 (2.9) vs 10.1(3.0) min, respectively; mean difference, 3.6 min; 95% confidence interval (CI), 1.9 to 5.3; P < 0.001], obeying commands [6.6 (2.7) vs 10.1 (3.1) min, respectively; mean difference, 3.5 min; 95% CI, 1.9 to 5.2; P < 0.001], and tracheal extubation [7.0 (2.5) vs 10.6 (3.0) min, respectively; mean difference, 3.6 min; 95% CI, 1.9 to 5.1; P < 0.001]. Similarly, the times from discontinuation of volatile anesthetics to orientation to the patients' full name, date, and place were significantly shorter in the desflurane group compared with the sevoflurane group. There were no significant differences between groups on a 100-mm visual analogue scale assessing postoperative nausea and vomiting, eye pain, and patient satisfaction regarding anesthesia.

CONCLUSION

Changing the anesthetic agent from sevoflurane to desflurane after sevoflurane induction provides faster emergence and recovery compared with sevoflurane anesthesia. This study protocol was registered at http://www.umin.ac.jp/ctr/index.htm , (UMIN000009941).

The effective bolus dose of remifentanil to facilitate laryngeal mask airway insertion during inhalation induction of sevoflurane in children

PURPOSE

The additional administration of remifentanil during inhalation induction with sevoflurane could provide better conditions for laryngeal mask airway (LMA) insertion than sevoflurane alone. This study was designed to evaluate the 50 % effective bolus dose (ED50) and 95 % effective bolus dose (ED95) of remifentanil required for LMA insertion in children during inhalation induction with sevoflurane.

METHODS

Pediatric patients aged 3-12 years requiring general anesthesia were recruited. A predetermined dose of remifentanil was injected over 30 s after the induction of general anesthesia with sevoflurane. LMA insertion was attempted 60 s after remifentanil injection. The dose of remifentanil was determined using the Dixon's up-and-down method, starting from 0.5 μg/kg (step size of 0.05 μg/kg).

RESULTS

The study was conducted until seven cross-over points and 29 children were collected. The ED50 of remifentanil for successful LMA insertion during sevoflurane inhalation induction in children was 0.168 ± 0.035 μg/kg using Dixon's method. In addition, the ED50 and ED95 of remifentanil from the probit analysis were 0.176 μg/kg (95 % confidence limits, 0.102-0.216 μg/kg) and 0.268 μg/kg (95 % confidence limits, 0.223-0.659 μg/kg), respectively.

CONCLUSION

The ED50 and ED95 of remifentanil for successful LMA insertion in children were estimated to be 0.176 (0.168) and 0.268 μg/kg during inhalation induction with 2.1 % sevoflurane.

Early life exposure to sevoflurane impairs adulthood spatial memory in the rat

Sevoflurane is a general anesthetic commonly used in the pediatric setting because it is sweet-smelling, nonflammable, fast acting and has a very short recovery time. Although recent clinical data suggest that early anesthesia exposure is associated with subsequent learning and memory problems, it is difficult to determine the exact scope of developmental neurotoxicity associated with exposure to specific anesthetics such as sevoflurane. This is largely due to inconsistencies in the literature. Thus, in the present studies we evaluated the effect of early life exposure to sevoflurane (1%, 2%, 3% or 4%) on adulthood memory impairment in Sprague-Dawley rats. Animals were exposed to different regimens of sevoflurane anesthesia on postnatal days (PNDs) 3, 7, or 14 or at 7 weeks (P7W) of age and spatial memory performance was assessed in adulthood using the Morris Water Maze (MWM). Rats exposed to sevoflurane exhibited significant memory impairment which was concentration and exposure duration dependent. Disruption of MWM performance was more severe in animals exposed on both PNDs 3 and 7 than in animals exposed on both PNDs 3 and 14. The younger the animal's age at the time of exposure, the more significant the effect on later MWM performance. Compared to the neonates, animals exposed at P7W were relatively insensitive to sevoflurane: memory was impaired in this group only after repeated exposures to low doses or single exposures to high doses. Early life exposure to sevoflurane can result in spatial memory impairments in adulthood and the shorter the interval between exposures, the greater the deficit.

A randomized controlled trial comparing Laryngeal Mask Airway removal during adequate anesthesia and after awakening in children aged 2 to 6 years

STUDY OBJECTIVE

To compare the frequency of airway complications during removal of the Laryngeal Mask Airway (LMA) in 2 to 6 year old pediatric patients.

DESIGN

Prospective randomized study.

SETTING

Operating room at a university hospital.

PATIENTS

92 ASA physical status 1 and 2 pediatric patients, aged 2 to 6 years.

INTERVENTIONS

Participants were randomized to two groups: anesthesia state (anesthesia group) and awake state (awake group). Anesthesia was induced and maintained with sevoflurane. Patients were allowed to maintain spontaneous respiration. In the anesthesia group, the LMA was removed during anesthesia with 2.2% of sevoflurane. In the awake group, the LMA was removed when patients met the recovery criteria, including facial grimace, spontaneous eye opening, and purposeful arm movement.

MEASUREMENTS

During and after removal of the LMA, the frequencies of airway-related complications including cough, severe salivation, LMA biting or teeth clenching, breath holding, laryngospasm, desaturation (SpO(2) < 95%), and vomiting, were recorded. The frequencies of upper airway obstruction and duration of emergence from anesthesia also were compared.

MAIN RESULTS

The frequency of airway-related complications was significantly less in the anesthesia group than the awake group (4.8% vs 37.2%, P = 0.001). Of the complications, cough, desaturation, excessive secretion, and LMA biting were less common in the anesthesia group. No differences between groups were noted in the frequency of upper airway obstruction and duration of emergence from anesthesia.

CONCLUSION

In 2 to 6 year old pediatric patients, an adequate anesthetic state is preferable to the awake state during LMA removal, producing fewer complications.

Minimum alveolar concentration of desflurane with fentanyl for laryngeal mask airway removal in anesthetized children

BACKGROUND

Desflurane provides rapid emergence from anesthesia. So, it can be used for the removal of a laryngeal mask airway in an anesthetized child. We conducted this study to determine the optimal endtidal concentrations of desflurane with fentanyl that would allow removal of a laryngeal mask airway without airway complication in children.

METHODS

Thirty-six children of American Society of Anesthesiologist status I between 1 and 10 year of age undergoing ophthalmic surgery were recruited. General anesthesia was induced with sevoflurane and oxygen given via mask and laryngeal mask airway inserted. Anesthesia was maintained with desflurane in 100% oxygen. At the end of the surgery, predetermined target concentration was maintained for 10 min and laryngeal mask airway removed. Each target concentration at the time of removal was predetermined by the Dixon up-down method (with 0.5% as a step size) starting at 5% endtidal concentration. A removal accomplished without coughing, teeth clenching, gross purposeful movement, breath holding, or laryngospasm, during or within 1 min after removal, was considered to be successful.

RESULTS

Endtidal concentration of desflurane required for successful laryngeal mask airway removal in 50% (ED50) was 3.56% desflurane (95% confidence limits, 3.22-3.87%) along with fentanyl.

CONCLUSION

Removal of laryngeal mask airway can be safely accomplished without coughing, moving, or any other airway complications at 3.57% endtidal concentrations of desflurane with fentanyl in 50% of anesthetized children.

Caudal analgesia reduces the sevoflurane requirement for LMA removal in anesthetized children

Background

An anesthetic state can reduce adverse airway reaction during laryngeal mask airway (LMA) removal in children. However, the anesthetic state has risks of upper airway obstruction or delayed emergence; so possibly less anesthetic depth is advisable. Caudal analgesia reduces the requirement of anesthetic agents for sedation or anesthesia; it is expected to reduce the sevoflurane requirement for LMA removal. Therefore, we determined the EC₅₀ of sevoflurane for LMA removal with caudal analgesia and compared that to the EC₅₀ without caudal analgesia.

Methods

Forty-three unpremedicated children aged 1 to 6 yr were enrolled. They were allocated to receive or not to receive caudal block according to their parents' consent. General anesthesia were induced and maintained with sevoflurane and oxygen in air. EC₅₀ of sevoflurane for a smooth LMA removal with and without caudal analgesia were estimated by the Dixon up-and-down method. The LMA was removed when predetermined end-tidal sevoflurane concentration was achieved, and the sevoflurane concentration of a subsequent patient was determined by the success or failure of the previous patient with 0.2% as the step size; success was defined by the absence of an adverse airway reaction during and after LMA removal. EC₅₀ of sevoflurane with caudal block, and that without caudal block, were compared by a rank-sum test.

Results

The EC₅₀ of sevoflurane to achieve successful LMA removal in children with caudal block was 1.47%; 1.81% without caudal block. The EC₅₀ were significantly different between the two groups (P < 0.001).

Conclusions

Caudal analgesia significantly reduced the sevoflurane concentration for a smooth LMA removal in anesthetized children.

Airway responses to desflurane during maintenance of anesthesia and recovery in children with laryngeal mask airways

BACKGROUND

We sought to characterize the airway responses to desflurane during maintenance of and emergence from anesthesia in children whose airways were supported with laryngeal mask airways (LMAs).

METHODS/MATERIALS

Four hundred healthy children were randomized in a 3 : 1 ratio to either desflurane or isoflurane (reference group) during anesthetic maintenance. After induction of anesthesia, anesthesia was maintained with the designated anesthetic. The investigator chose the airway (LMA and facemask), ventilation strategy and when to remove the LMA. The incidence of airway events during maintenance, emergence and recovery was recorded.

RESULTS

Ninety percent of children received LMAs. The frequency of major airway events after desflurane (9%) was similar to that after isoflurane (4%) (number needed to harm [NNH] 20), although the frequency of major events after the LMA was removed during deep desflurane anesthesia (15%) was greater than during awake removal (5%) (NNH 10) (P < 0.006) and during deep isoflurane removal (2%) (NNH 8) (P < 0.03). The frequency of airway events of any severity after desflurane was greater than that after isoflurane (39% vs 27%) (P < 0.05). The frequencies of laryngospasm and coughing of any severity after desflurane were greater than those after isoflurane (13% vs 5% and 26% vs 14%, respectively) (P < 0.05).

CONCLUSIONS

When an LMA is used during desflurane anesthesia in children, fewer airway events occur when it is removed when the child is awake. Although the time to discharge from recovery was not delayed and no child required overnight admission, caution should be exercised when using an LMA in children who are anesthetized with desflurane.

[Laryngospasm]

BACKGROUND AND OBJECTIVES

Airways management is fundamental for anesthesiologists, especially during induction of anesthesia and after extubation, when laryngeal spasm is more common. The anesthesiologist should know pharyngeal-laryngeal physiology and the risk factors for airways obstruction, since this is a potentially severe complication with a multifactorial etiology that can develop during anesthesia and whose consequences can be catastrophic. A delay in the diagnosis or treatment and its evolution can lead to hypoxemia, acute pulmonary edema, and, eventually, death of the patient. In this context, the objective of this report was to review the measures that should be taken in cases of laryngospasm because adequate oxygenation and ventilation may be compromised in this situation.

CONTENTS

This review article presents the mechanisms of airways management, discussing the most relevant aspects and etiology, pathophysiology, treatment, and prevention of laryngospasm.

CONCLUSIONS

The literature has several recommendations on the treatment or prevention of laryngospasm, but none of them is completely effective. Due to its severity, further studies on measures to prevent this complication are necessary.

Safe and easy emergence from anesthesia in adults following removal of laryngeal mask airway: utility of oral airway and T-connector

Removal of the laryngeal mask airway (LMA) can be executed while patients are deeply anesthetized or awake. Recent publications have focused on suitable anesthetic concentrations in the brain for removal of LMA in anesthetized patients. Here, we describe an easy and safe method for removal of LMA during deep anesthesia.

A comparison of the end-tidal sevoflurane concentration for removal of the laryngeal mask airway and laryngeal tube in anesthetized children

BACKGROUND

In this study we quantified and compared the optimal sevoflurane concentration required to prevent coughing or moving during or after removal of the laryngeal mask airway (LMA) and the laryngeal tube (LT) in anesthetized children.

METHODS

Forty unpremedicated children, aged 8 mo to 12 yr, were randomly allocated to receive the LMA or LT. General anesthesia was induced via mask with sevoflurane and the LMA or LT was inserted. Anesthesia was maintained with sevoflurane and oxygen. At the end of surgery, a predetermined end-tidal sevoflurane concentration was maintained for at least 10 min and the LMA or LT was removed. Using Dixon's up-down method, the concentration for LMA and LT removal was determined by adjusting the dose by a 0.2% increment. Success was defined by the absence of coughing, teeth clenching, gross purposeful movement, breath holding, laryngospasm, and desaturation.

RESULTS

The end-tidal concentration of sevoflurane to achieve successful LMA removal in 50% of children was 1.90%, in 95% of children was 2.15%. For the LT, the concentrations were 1.83% and 2.00%. The 50% effective dose values did not differ significantly between groups.

CONCLUSIONS

LMA and LT removal in 95% of anesthetized children (aged 8 mo to 12 yr) can be safely accomplished without coughing, moving, or any other airway complications at 0.86 and 0.80 minimum alveolar anesthetic concentration, respectively, and a similar concentration should be used for removal of the LT or LMA in children.