LMA Insertion Research Articles

Comparative Study of laryngeal mask airway Supreme and laryngeal mask airway Classic in paralyzed patients

Aim and Objectives: The present study was undertaken to compare the LMA Classic with LMA Supreme in assessing the ease of insertion, number of attempts, time for insertion, any unwanted responses, stability of device, peak airway pressure, leak volume and leak fraction and postoperative complications. Methods: A total of 274 patients of ASA grade 1 and 2 were included in the study and divided into two groups with 137 patients in each group: the LMA Classic group (group C) and LMA Supreme group (group S). All patients were induced with propofol 2.5 mg/kg and atracurium 0.5mg/kg after that appropriate sized supraglottic airway device was inserted. The ease of insertion, number of attempts, duration of insertion, stability of device, peak airway pressure, leak volume and leak fraction and postoperative complications were recorded. Results: The insertion of Supreme LMA was very easy in 134 patients and was easy in 3 patients, difficult in 0 patients while the insertion of Classic LMA was very easy in 122 patients, easy in 15 patients and difficult in 0 patients. The first attempt insertion rate was more with Supreme LMA as compared to Classic LMA. The mean duration of insertion was significantly lower with Supreme LMA than with Classic LMA. The mean airway pressure was similar in both groups. Both devices were stable. Leak volume and Leak fraction was significantly higher in Classic LMA than Supreme LMA. Peri-operative complications were not significantly different between Supreme LMA and Classic LMA. Conclusions: The LMA Supreme is superior to the LMA Classic because of its ease of insertion with lesser leak volume and leak fraction and better first attempt insertion rate.

Study of the laryngeal mask airway for airway management in childrenwith acute severe tracheobronchial foreign body

Objective:To explore the application of laryngeal mask airway in the management of respiratory tract after acute and severe tracheal foreign body removal in children, and to provide a safe and effective treatment for clinical treatment.Method:Seventy cases of children with acute severe tracheal or bronchial foreign body requiring mechanical ventilation transition were randomized to receive, one group was using laryngeal mask airway for airway management after the foreign body was extracted and the bronchoscope was pulled out. Another group was using tracheal intubation. Both groups were received the same general anesthesia induction and maintenance. The blood pressure before induction, before and after insertion of LMA (TT), before and after extubation of LMA(TT) were monitored and recorded. Heart rate, tidal volume,respiratory rate,pulse oxygen saturation, and end-tidal carbon dioxide partial pressure were recorded at the same time in both groups. Airway complications during the recovering between two groups were compared.Result:HR, BP have no significant difference in LMA group before and after implantation LMA (P> 0.05). HR and BP were increased significantly after intubation (P< 0.05) in TT group; Airway pressure, SpO₂ and PET CO₂ exhibited no significant difference between two groups P> 0.05); LMA group has less airway complications than TT group during the recovering.Conclusion:Application of LMA for anesthetic airway management after tracheobronchial foreign body was extracted in children made both less effect on respiratory and circulatory system the regular using tracheal intubation and less damage to the respiratory tract. In addition,the recovery time in LMA group is much shorter than that of TT group.

Comparação da concentração de sevoflurano para a inserção de ML proseal e intubação traqueal em crianças (correlação com BIS)

BackgroundSevoflurane is an inhalational agent of choice in paediatric anaesthesia. For management of airways in children a suitable alternative to ETT is a paediatric proseal laryngeal mask airway (benchmark second generation SAD). Various studies have shown that less sevoflurane concentration is required for LMA insertion in comparison to TI. BIS is a useful monitor of depth of anaesthesia. AimsTo compare concentration of sevoflurane (end tidal and MAC value) required for proseal laryngeal mask airway insertion and tracheal intubation in correlation with BIS index. MethodThe prospective randomised single blind study was done in children between 2 and 9 years of ASA I and II and they were randomly allocated to Group P (proseal laryngeal mask airway insertion) and Group TI (tracheal intubation). No sedative premedication was given. Induction was done with 8% sevoflurane and then predetermined concentration was maintained for 10min. Airway was secured either by proseal laryngeal mask airway or endotracheal tube without using muscle relaxant. End tidal sevoflurane concentration, MAC, BIS, and other vital parameters were monitored every minute till insertion of an airway device. Insertion conditions were observed. Statistical analysis was done by Anova and Student's t test. ResultsDifference between ETLMI (2.49±0.44) and ETTI (2.81±0.65) as well as MACLMI (1.67±0.13) and MACTI (1.77±0.43) was statistically very significant, while BISLMI (49.05±10.76) and BISTI (41.25±3.25) was significant. Insertion conditions were comparable in both the groups. ConclusionWe can conclude that in children airway can be secured safely with proseal laryngeal mask airway using less sevoflurane concentration in comparison to tracheal intubation and this was supported by BIS index.

A controlled, double blind, study of adding Nalbuphine to Propofol for laryngeal mask insertion conditions and hemodynamics in adults

PurposeThe purpose of this study was to evaluate laryngeal mask airway placement conditions achieved with Nalbuphine/Propofol combination when given intravenously as well as hemodynamic changes if any.Methods60 ASA grade 1 and 11 patients of age group 20–60 years, scheduled for general anesthesia with spontaneous breathing were randomly allocated to receive intravenously either Fentanyl 2 μg/kg, controlled group (Group F, n = 30) or Nalbuphine 0.2 mg/kg (Group N, n = 30), before induction of anesthesia with Propofol 2–2.5 mg/kg. Heart rate and arterial blood pressure were measured before induction of anesthesia and at 1, 3, and 5 min after LMA insertion. Assessment of LMA insertion was done using 6 variables: mouth opening, gagging, swallowing, head and limb movements, laryngospasm and resistance to insertion. Incidence and duration of apnea were recorded.ResultsThe incidence of coughing/gagging was higher in the F group (50%) compared to the N group (30%), (P = 0.019). Swallowing was also statistically significant (P = 0.017), being higher in F group (50%), compared to N group (16.6%). Limb moving followed the same pattern being higher in the F group (40%) compared to (13.3%) in the N group, (P = 0.008). Laryngospasm was seen in neither group. There was also statistically significant difference (P = 0.007) in the incidence of apnea between the control group (F) 86.6% and (N) group. Heart rate variation and MAP changes were not statistically significant in either F or N groups.ConclusionThe addition of Nalbuphine to Propofol for LMA insertion provides excellent insertion conditions with stable hemodynamics in adults.

Comparison of Four Different Supraglottic Airway Devices in Terms of Efficacy, Intra-ocular Pressure and Haemodynamic Parameters in Children Undergoing Ophthalmic Surgery.

The aim of this study was to compare insertion parameters of four different types of supraglottic airway devices (SGAD) (Classic LMA, I-gel LMA, Proseal LMA, Cobra PLA) in children undergoing ophthalmic surgery and to determine the effect on intra-ocular pressure (IOP) and haemodynamic responses during insertion. Sixty American society of Anesthesiologists (ASA) I-II children aged 1-10 years undergoing extra-ocular ophthalmic surgery were randomly divided into four groups (Group LMA, Group I-gel LMA, Group PLMA and Group CPLA) in this prospective, randomised study. Anaesthesia was induced with decreasing sevoflurane concentrations (8%-2%) in a mixture of 50% N2O-O2. All SGADs were inserted under deep anaesthesia. The characteristics of insertion (number of attempts, ease and time), oropharyngeal leak pressure (OLP) and complications were recorded. IOP in both eyes, heart rate (HR), mean arterial pressure (MAP) and EtCO2 were measured before and 2 and 5 min after insertion of the SGADs. There was no difference between the groups in terms of the characteristics of insertion. The mean IOP did not increase significantly in all groups. MAP and HR changes were similar among the groups during follow-up. In all groups, HR increased 2 min after insertion (statistically insignificant) and returned to the baseline value 5 min after insertion. A statistically significant correlation was seen between HR increase and IOP values before and after insertion of the SGADs (p=0.006, correlation coefficient=0.352). Desaturation was seen in one patient in Groups LMA, PLMA and CPLA, and laryngospasm was seen in two patients in Group CPLA and in one patient in Group LMA. It was seen that during insertion of Classic LMA, I-gel LMA, Proseal LMA and Cobra PLA, IOP did not increase and haemodynamic stability was maintained in children undergoing extra-ocular ophthalmic surgery.

Comparison of efficacy of propofol and sevoflurane for laryngeal mask airway insertion during elective surgeries

This study was conducted in the Department of Anesthesiology, Holy Family Hospital Rawalpindi from 5 October 2011 to 5 April 2012 after approval of hospital ethics committee. Three hundred and eighteen patients fulfilling the inclusion criteria were selected in the study by non-probability consecutive sampling after taking informed written consent. Patients between the ages of 20 to 40 years were included, belonging to ASA class I and II, requiring General Anesthesia with Laryngeal Mask Airway for different surgical procedures. They were divided into two equal groups by computer generated random numbers. Group A comprised of one hundred and fifty eight patients in whom intravenous propofol was given for induction of anesthesia and Laryngeal mask insertion. Group B comprised of one hundred and fifty eight patients in whom inhalational induction with sevoflurane was done for Laryngeal mask insertion. Conduct of anesthesia was maintained similar in both groups. Cough and gag reflexes were observed in both groups at the time of Laryngeal mask insertion. Drug under study was said to be effective, if it is associated with no cough and gag reflex during Laryngeal mask insertion. All the data was analyzed by SPSS version 15. It was observed that 6.3% patients of group A (propofol) had positive cough reflex as compare to 13.2%% patients of group B (sevoflurane). The difference was statistically significant (p=0.038). While the incidence of gag reflex in group A was 8.2% and group B was 14.5%. But the difference was not found to be statistically significant (p=0.077). Propofol is more effective than sevoflurane for smooth LMA insertion during elective surgeries.DOI: http://dx.doi.org/10.3126/jcmc.v5i1.12562

Comparison of Sevoflurane and Propofol for Laryngeal Mask Airway Insertion in Children

INTRODUCTION: The major responsibility of an anaesthesiologist is to provide adequate ventilation for the patient by providing unobstructed airway. An anaesthetic technique is safe only when diligent efforts are devoted to maintain an intact functional airway. To maintain airway in an anaesthetized or unconscious patient we have supraglottic devices like anatomical face mask, laryngeal mask airway, cuffed oropharyngeal airway and combitube. Laryngeal mask airway was invented by Dr. ARCHIE BRAIN, United Kingdom in 1981. The LMA is an ingenious supraglottic airway device that is designed to provide and maintain a seal around the laryngeal inlet for spontaneous ventilation and allow controlled ventilation at modest levels of positive pressure. In controlled ventilation peak inflation pressure should not exceed 25cm H2O. An outstanding feature of LMA is that it provides a rapid clear airway in vast majority of patients and it is both faster and easier to insert than a tracheal tube. LMA can be used for pediatric and adult patients undergoing daycare surgeries. Successful insertion of LMA requires sufficient depth of anaesthesia and depression of airway reflexes to avoid gagging, coughing and laryngeal spasm. Propofol is the induction agent most commonly used for insertion of LMA. Sevoflurane is a recently introduced volatile anaesthetic agent which allows rapid smooth inhalational induction with excellent recovery. This study was being conducted to compare Sevoflurane and Propofol for insertion of laryngeal mask airway in children. This study was carried out in Dept. of Anaesthesiology, Stanley medical college, Chennai. AIM OF THE STUDY: The aim of the study is to compare the conditions of Laryngeal Mask Airway insertion in children after induction of anaesthesia with either inhalation of sevoflurane or intravenous propofol. The time taken for induction, time taken for jaw relaxation, time to LMA insertion, hemodynamic parameters, complications during induction and LMA insertion are compared. MATERIALS AND METHODS: Sixty patients of ASA physical status 1&2 undergoing elective minor surgical procedures below umbilicus lasting less than 60 mins. were included in the study. Patients belonged to age group of 4 – 12 of both sexes. It was a prospective randomized controlled study. The study was approved by institutional ethical committee and parent provided written informed consent before induction. Inclusion Criteria: 1. ASA I and II physical status. 2. No predicted airway difficulty. 3. Elective minor surgical procedures below umbilicus lasting less than 60 min. Exclusion Criteria: 1. Patients at risk of aspiration – upper GI surgery, gastroesophageal disease, not fasted. 2. Patients who require high positive pressure ventilation – eg. Pulmonary fibrosis. 3. Known allergy to any anaesthetic. MATERIALS: 1. Classic Laryngeal mask airways of appropriate size, 2. Propofol 1%, 3. Sevoflurane, 4. Fentanyl and glycopyrrolate, 5. Appropriate size oral airways, 6. 2,5 and 10 ml syringes, 7. Lubricant jelly. Preparation of the Patient: Informed consent from the parent obtained. All patients were fasted as per NPO guidelines. Premedication: Syp. Triclofos 60 mg/kg po given 45 min before shifting the child to operating room. METHODS: 1. Basal heart rate, blood pressure and oxygen saturation were recorded. 2. Intravenous access established. 3. Inj. Glycopyrrolate 10μg/kg and Inj. Fentanyl citrate 2 μg/kg i.v. given on table. 4. Preoxygenation with 100% O2 done for 3 min. SUMMARY: We assessed the conditions for insertion of LMA in two groups of patient receiving either inhalational sevoflurane or intravenous propofol and the following observations were made. • There were no significant differences between the two groups in demographic data. • The time to induction is less with sevoflurane compared to propofol in this study, though statistically not significant. • The time to jaw relaxation and the time to LMA insertion is less with propofol, with statistical significance. • The insertion is more successful by 1st attempt in the propofol group. But this is not statistically significant. • There are few cases who had movements during induction in propofol group and few cases had transient apnea during induction in sevoflurane group. • There is no significant difference between both groups in the incidence of coughing, gagging and laryngospasm. • There is significant difference in pulse rate in both groups. The pulse rates in propofol group decreased from baseline but within acceptable limits. In Sevoflurane group pulse rate increased from baseline during induction and LMA insertion, within acceptable limits. • The decrease in mean arterial pressure is observed in both groups and is not statistically significant. CONCLUSION: In conclusion, Propofol and Sevoflurane are equally effective for LMA insertion in children. However, Propofol has a faster insertion time due to early onset of jaw relaxation compared to sevoflurane and high success rate in 1st attempt for LMA insertion whereas Sevoflurane has better hemodynamic stability and less side effects compared to propofol.

Comparison of propofol versus propofol with low dose scoline to evaluate lma insertion

Background: LMA insertion requires sufficient depth of anesthesia and depression of airway reflexes. Propofol is the agent of choice for LMA insertion as it is very effective in suppressing cough and gag reflexes. On the other hand addition of low dose scoline improves correct position of the laryngeal mask. Our main aim of study was to compare the hemodynamic changes, time taken for LMA insertion and ease of LMA insertion using Propofol v/s propofol with low dose scoline in both groups. Method: The study was conducted in sixty ASA-1 and ASA-2 grade patients. All patients were investigated preoperatively for routine investigations. Written informed consent was taken. After applying monitors all patients were premedicated with Inj. Ondensetron (4 mg), Inj. Glycopyrrolate (0.2 mg), injection midazolam 0.03 mg/kg IV two minutes before three minutes of preoxygenation. Gr p received Inj propofol 2.5 mg/kg/iv and Gr (P+S) received Inj propofol 2.5 mg/kg/iv with Inj Scoline 0.2 mg/kg/iv. Overall Grading of Insertion score, Rescue Drug Usage Grade, LMA Insertion time were noted. Patients were observed for any complication postoperatively. Result: Jaw opening was comparable but statistically insignificant in both groups. No vigorous movements were noted in (P+S) group while 6.67% patients in P group had vigorous movements. This was statistically significant (p

Comparative evaluation of supraglottic airway devices I-Gel versus LMA-supreme in patients undergoing surgery under general Anaesthesia

Background and Aim: Supraglottic airway devices are increasingly being used as an excellent alternative to mask ventilation and tracheal intubation with least complications. The present randomized, prospective study was conducted to compare the I-Gel with LMA-Supreme with respect to time taken for insertion, insertion success rate, ease of insertion of gastric tube, hemodynamic changes before and after insertion and post-operative airway morbidity. Materials and Methods: Sixty American Society of Anaesthesiologist (ASA) grade-I and II patients between 18-60 years age, of either sex, were randomly assigned to two groups of 30 patients each. Group A: I-gel was inserted and Group B: LMA- supreme was inserted by grasping firmly along the integral bite block (Digital Technique). Hemodynamic responses were recorded before induction and at the intervals after insertion of LMA Supreme/I-Gel. Time taken for insertion, insertion success rate and ease of insertion of gastric tube was noted. Patients were inspected for any trauma to mouth, lip and tongue in the immediate postoperative period and asked about sore throat, hoarseness and dysphonia 24 hours after the surgery. Statistical analysis was carried out with student’s t-test and chi-square test and value of P?0.05 was considered statistically significant. Results: Insertion time of I-Gel (11.07±1.93 seconds) was faster than the LMA-Supreme (12.50±2.35 seconds) and the results were statistically significant (P=0.01). Ease of insertion of gastric tube was more in LMA Supreme (28/30) as compared to I Gel (26/30) but statistically this difference came out to be non-significant (P=0.157).The two groups were comparable as far as the insertion success rate , hemodynamics and post-operative airway morbidity were concerned. Conclusion: I-Gel is better than LMA-Supreme in terms of faster insertion time. Insertion success rate, ease of insertion of gastric tube, hemodynamics and post-operative airway morbidity is comparable in

Comparison of sevoflurane concentration for insertion of proseal laryngeal mask airway and tracheal intubation in children (correlation with BIS)

BackgroundSevoflurane is an inhalational agent of choice in paediatric anaesthesia. For management of airways in children a suitable alternative to ETT is a paediatric proseal laryngeal mask airway (benchmark second generation SAD). Various studies have shown that less sevoflurane concentration is required for LMA insertion in comparison to TI. BIS is a useful monitor of depth of anaesthesia. AimsTo compare concentration of sevoflurane (end tidal and MAC value) required for proseal laryngeal mask airway insertion and tracheal intubation in correlation with BIS index. MethodThe prospective randomised single blind study was done in children between 2 and 9 years of ASA I and II and they were randomly allocated to Group P (proseal laryngeal mask airway insertion) and Group TI (tracheal intubation). No sedative premedication was given. Induction was done with 8% sevoflurane and then predetermined concentration was maintained for 10min. Airway was secured either by proseal laryngeal mask airway or endotracheal tube without using muscle relaxant. End tidal sevoflurane concentration, MAC, BIS, and other vital parameters were monitored every minute till insertion of an airway device. Insertion conditions were observed. Statistical analysis was done by ANOVA and Students t test. ResultsDifference between ETLMI (2.49±0.44) and ETTI (2.81±0.65) as well as MACLMI (1.67±0.13) and MACTI (1.77±0.43) was statistically very significant, while BISLMI (49.05±10.76) and BISTI (41.25±3.25) was significant. Insertion conditions were comparable in both the groups. ConclusionWe can conclude that in children airway can be secured safely with proseal laryngeal mask airway using less sevoflurane concentration in comparison to tracheal intubation and this was supported by BIS index.

Comparison of haemodynamic alteration with laryngeal mask airway and endotracheal tube in intermediate duration of gynaecological operation

Background Laryngeal mask airway insertion causes less changes of haemodynamic parameters. As haemodynamic changes during laryngoscopy and endotracheal intubation as result of intense stimulation of sympathetic nerves system. Objective To find out the effective airway management by LMA during controlled ventilation, to avoid laryngoscopic and intubation induced haemodynamic changes and to avoid laryngospasm and bronchospasm. Method A total number of 100 patients ASA grade I &amp; II were selected randomly as per inclusion and exclusion criteria in two groups. Fifty in each group. In group A used LMA and in group B used ETT during general anaesthesia in intermediate duration of gynaecological operation. Pulse,NIBP,SpO2 were recorded in perioperatively. Result Pulse, blood pressure were significant between the two groups (p&lt;0.00) but in SpO2 was insignificant except in 2 min of intraoperative which was significant. (p&lt;0.013). Conclusion LMA insertion causes less changes of haemodynamic parameters when compared with that of ET intubation. Our finding suggests that LMA can be safe and beneficial alternative to ETT. DOI: http://dx.doi.org/10.3329/jbsa.v23i2.18174 Journal of BSA, 2009; 23(2): 51-55

Remifentanil dose for laryngeal mask airway insertion with a single standard dose of propofol during emergency airway management in elderly patients.

BackgroundThis study determined the dose of remifentanil to use during insertion of a Classic™ laryngeal mask airway (LMA, The Laryngeal Mask Co., Nicosia, Cyprus) in elderly patients during emergency airway management when combined with a single dose of propofol.MethodsPatients aged 65-80 years were enrolled. Anesthesia was induced with propofol 1 mg/kg, and then a blinded dose of remifentanil was infused over 30 s after confirming the patient's loss of consciousness. The dose of remifentanil was determined using Dixon's up-and-down method, starting at 0.5 µg/kg (a step size of 0.1 µg/kg). Insertion of the LMA was attempted 60 s after loss of consciousness.ResultsIn total, 23 patients were recruited and the mean age ± standard deviation was 72 ± 3 years. The effective dose for successful LMA insertion in 50% of the patients (ED50) was 0.20 ± 0.05 µg/kg. No patient needed more than 0.3 µg/kg.ConclusionsRemifentanil 0.20 ± 0.05 µg/kg with propofol 1 mg/kg resulted in excellent LMA insertion in 50% of elderly patients without significant hemodynamic changes during emergency airway management.

Anaesthesia and orphan disease

Anaesthesia and orphan disease

Hemodynamic Changes following Anesthesia Induction and LMA Insertion with Propofol, Etomidate, and Propofol + Etomidate.

LMA is a simple supra-laryngeal device which is used to establish and maintain airway. Despite the common use of the LMA, there are no optimal methods for induction of anesthesia that can guarantee a proper insertion. The purpose of this study is comparing three methods of induction of anesthesia (Propofol, Etomidate, Propofol+Etomidate) in the hemodynamic stability after LMA insertion in elective surgeries. A total of 90 patients with ASA classes I and II undergoing elective surgeries were randomly allocated into one of the following three groups. Before anesthesia induction, all patients were premedicated. Anesthesia induction methods included: Group P (propofol 2.5 mg/kg), Group E (etomidate 0.3 mg/kg) and Group P+E (propofol 1 mg/kg plus etomidate 0.2 mg/kg). Heart rate, systolic blood pressure, diastolic blood pressure, and mean arterial pressure were measured before induction and 30 seconds after induction. Apnea time is recorded in all patients. Number of attempts to laryngeal mask insertion, ease of placement, were compared in three groups. There was no significant difference between demographic data and BIS, SaO2, Etco2 associated diseases, in three group (P>0.5).There is significant difference in hemodynamic (Systolic, diastolic and mean blood pressures) changes between group 1 in comparison with group 2 and group 3. HR was significantly lower in group 1 than group 2 (P=0.16). There was significant difference in the number of attempts and ease of LMA insertion between group 2 in comparison with group 3 and group 1. The duration of apnea in group 2 was a (8.67± 6) min, where as it was (18.10±6.25) min in group 1 and (12.03±6.4) min group 3. Etomidate plus propofol is an effective and alternative to propofol and etomidate for facilitating LMA insertion with the added advantage of lack of cardio-vascular depression.

Postępowanie anestezjologiczne podczas endowaskularnego leczenia niepękniętych tętniaków wewnątrzczaszkowych

Endovascular techniques for treatment of intracranial aneurysms are increasingly commonly applied. In general, the procedures are short, require general anaesthesia and complete immobilisation of patients. The aim of the present study was to assess the usefulness of general anaesthesia with propofol and laryngeal mask airway for endovascular management of intracranial aneurysms based on analysis of haemodynamic stability. The study encompassed 26 patients undergoing endovascular treatment of intracranial aneurysms. The mean arterial pressure (MAP), heart rate (HR), bispectral index (BIS), end-tidal CO₂(E(T)CO₂) and haemoglobin saturation with oxygen (SpO₂ ) were determined at eight measurement points: T₁ - before anaesthesia induction, T₂ - after induction, T₃ - after LMA insertion, T₄ - during arteriography, T₅ - during "coiling" , T₆ - at completion of propofol infusion, T₇ - before LMA removal, T₈ - after LMA removal. MAP and HR were found significantly reduced between T₂ and T₁ . To maintain BIS within the range of 40-60, the following propofol infusion rates (in mg kg b.w.⁻¹ h⁻¹ ) were required: T₂ - 4.5 ± 0.3; T₃ - 4.6 ± 0.7; T₄ - 4.5 ± 0.8 and T₅ - 4.4 ± 0.6. E T CO₂ and SpO₂ were not demonstrated to be changed. The mean duration of anaesthesia and of recovery was 64.3 ± 21.8 and 8.9 ± 4.8 min, respectively. General anaesthesia with propofol and LMA ensures suitable conditions for endovascular treatment of intracranial aneurysms.

Sevoflurane End-Tidal to Effect-Site Equilibration in Women Determined by Response to Laryngeal Mask Airway Insertion

End-tidal concentrations (CET) have been used to guide delivery of inhaled anesthetic drugs for many years. Effect-site concentrations (Ceff) are a frequently used guide to therapy with IV drugs and should also be of benefit with inhaled drugs, especially during periods of rapid change. For Ceff to be useful, the appropriate levels required for any given end point, and the delay between central compartment and effect, need to be defined. In this study, we explored these relationships for the effect of response to insertion of the classic laryngeal mask airway (cLMA) and compared the utility of CET and Ceff-guided cLMA insertion. We studied 30 ASA physical status I or II patients in whom induction with sevoflurane alone and use of the cLMA were appropriate. After oxygen administration from a circle system with a total gas flow of 6 L/min, the sevoflurane vaporizer dial was set to 6%. cLMA insertion was attempted at a predetermined Ceff calculated in real time based on measured CET. Target levels were chosen using up-and-down methodology. The initial value was 2.5 vol% with a step size of 0.2 vol%. Subjects showing a gross motor response were responders, and the target was increased for the next subject. Those without such a response were nonresponders, and the target was decreased for the next subject. Data collection continued until after 7 transitions from nonresponder to responder. For each subject, after the first transition, we calculated a Ceff time series from the measured CET time series for 11 t(1/2)ke0 values between 0.5 and 5.0 minutes. We combined data from 2 studies of equilibrium 50% effective concentration (EC50) for LMA insertion to derive a pooled EC50 of 2.17%. We determined graphically the t(1/2)ke0 that gave a mean EC50 of 2.17% in our subjects. We constructed receiver operator characteristic curves to compare the utility of CET and Ceff-guided cLMA insertion. The 30 patients studied were all women, ASA physical status I or II, aged between 22 and 66 years (mean 38). Consciousness was lost after 99.2 (SD 11.1) seconds, and the target for cLMA insertion reached after 256 (57) seconds. The optimum t(1/2)ke0 was 2.25 minutes (95% confidence interval, 2.0-2.5 minutes). The area under the receiver operator characteristic curves was significantly different at 0.87 (SE 0.06) for Ceff and 0.63 (0.11) for CET. This study confirmed that real-time calculation and display of Ceff based on measured CET values are feasible. We determined the optimum t(1/2)ke0 for sevoflurane for the effect of cLMA insertion as 2.25 minutes, similar to that determined for loss of consciousness using the raw electroencephalogram. We also showed that Ceff is a more reliable (P < 0.05) guide to successful cLMA insertion than CET.

A clinical comparison of ketofol (ketamine and propofol admixture) versus propofol as an induction agent on quality of laryngeal mask airway insertion and hemodynamic stability in children.

Background:In spite of being the preferred induction agent for LMA insertion, propofol has many undesirable side effects including dose-related cardiorespiratory depression and local pain at injection site. Ketofol as a novel induction agent has been introduced recently with comparable efficacy and improved hemodynamic controlObjective:To investigate ketofol as a suitable induction agent alternative to propofol for insertion of LMA in children considering insertion conditions, hemodynamic stability, local pain at injection site, and recovery.Materials and Methods:In this randomized, double-blind study, 100 children were randomly assigned into two groups of 50 patients each in which induction was performed with either propofol or ketofol. Providers were given one 20 ml syringe [represent either 2 mg/kg of propofol (P group) or 0.75 mg/kg of ketamine and 1.5 mg/kg of propofol (KP group)] and one 10 ml syringe for rescue if needed [represent 1 mg/kg of propofol (P group) or 0.25 mg/kg of ketamine and 0.5 mg/kg of propofol (KP group)]. After monitoring with bispectral index (BIS), general anesthesia was induced by infusion with a syringe perfuser at a constant rate of 250 ml/h with either of the two agents till the BIS values decreased to 40. Mean arterial pressure (MAP), heart rate (HR) were measured every 30 seconds up to 5 minutes after LMA placement. The time till BIS values decreased to 40 was measured. All children were evaluated for incidence of apnea, pain on injection, jaw relaxation, conditions for LMA insertion, and complications such as muscle rigidity, hallucinations, and excessive secretions.Results:Induction time (time to reach BIS of 40) was faster in the KP group (150 ± 23.5 seconds) than in the P group (205 ± 37.4 seconds). The incidence of injection pain was significantly lower in the KP group (10%) than in the P group (80%). Excellent jaw relaxation and full mouth opening were higher in the KP group [45 patients (90%)] than in the P group [38 patients (76%)]. Excellent LMA insertion conditions were observed in 45 patients (90%) in the KP group and 38 patients (76%) in the P group. The KP group showed preserved hemodynamic stability (mean blood pressure, heart rate) with less incidence and duration of apnea compared to the P group.Conclusion:ketofol is a safe and effective alternative induction agent for LMA insertion in children with rapid onset of action and lower incidence of injection pain. It provided better LMA insertion conditions, improved hemodynamic stability with less prolonged apnea when compared with propofol.

JDSA Journal Abstracts

JDSA Journal Abstracts

General Anesthesia Preceded by Awake-Trial of LMA in a Child with Freeman-Sheldon Syndrome

We report the anesthetic management of a five-year-old girl child with Freeman-Sheldon syndrome undergoing surgical correction of the restricted mouth opening and the deformities of the feet. The anticipated difficult airway (mouth opening of 12 mm, MallampatiIV) was safely and successfully managed using an “awake-trial” of LMA before the actual LMA insertion under general anesthesia. Subsequent tracheal intubation through the LMA was done using a Desjardin-gallstone-forceps as a stabilization device. Perioperative period was uneventful with the complete avoidance of halogenated inhalational anesthetic agents, suxamethonium, metoclopramide, droperidol, and neuromuscular blocking agents.

Comparison of the Flexi laryngeal mask airway vs. endotracheal intubation for paediatric ophthalmic surgery

Background: The study aims at assessing the advantages of Flexi laryngeal mask airway (Flexi LMA) over endotracheal intubation in minimizing the pressor response as well as the rise in intraocular pressure in paediatric patients undergoing ophthalmic operations. Method: Sixty paediatric patients aged 4-12 years of ASA grade I and II meant for ophthalmic surgeries were divided into two groups of 30 patients each by a computer generated table. Group I patients underwent Flexi Laryngeal mask airway insertion and group II patients received endotracheal intubation. All the patients received similar premedication and anaesthetic drugs on per kg body weight basis. Patients were induced with Propofol and were maintained on Oxygen, nitrous oxide, Sevoflurane and rocuronium bromide. Changes in heart rate, mean arterial pressure and intraocular pressure were noted at different intervals which were markedly different in the two groups. Values so obtained were analysed using students t test and Z test respectively. A p value < 0.05 was considered to be statistically significant. Results: Similar but marked attenuated pattern of response was seen in group I patients compared to group II patients. Statistically significant difference between the two groups were seen in mean arterial blood pressure, heart rate and intra-ocular pressure(p < 0.05). Conclusion: Thus the use of Flexi LMA may offer some noticeable advantages over endotracheal intubation, especially for glaucoma patients as well as for those with some other associated congenital anomaly like The aim of this study was to assess the use of Flexi Laryngeal Mask Airway (Flexi LMA) as an alternative to avoid or to attenuate various noxious responses of endotracheal intubation including haemodynamic derangement and to intraocular pressure changes in paediatric patients who underwent ophthalmic surgeries. II. Method After obtaining approval from the ethical committee, sixty paediatric patients of ASA grade I and II scheduled to undergo ophthalmic surgeries under general anaesthesia, were studied after obtaining informed written consent from patient's parent. Patients in this study included those who had to undergo strabismus surgery, trabeculectomy, cataract surgery and Intraocolar lens implantation (I.O.L.). The patients were divided into two groups of 30 patients each by a computer generated table. Group I consisted of patients who were subjected to Flexi LMA insertion and Group II had undergone conventional laryngoscopy and endotracheal intubation (ETT). Patients with associated cardiovascular problems, upper respiratory tract infection, raised intraocular