Ease Of Laryngoscopy Research Articles

Intravenous magnesium sulfate improves orotracheal intubation conditions: A randomized clinical trial

BackgroundMuscle relaxation facilitates orotracheal intubation, but in some situations, neuromuscular blocking agents may be contraindicated. AimTo study the effect of intravenous magnesium sulfate perfusion before induction on orotracheal intubation conditions and the pressor response upon intubation. MethodsThis prospective, randomized, double-blind trial compared magnesium sulfate with saline solution as a placebo. The patients were randomized into two groups: the magnesium group (Group Mg+), which received 50 mg/kg of magnesium sulfate in 100 ml of saline 15 min before induction of anesthesia, and the saline group (Group Mg-), which received only 100 ml of saline 15 min before induction of anesthesia without magnesium sulfate. The induction in both groups was performed without neuromuscular blocking agents.Intubation conditions in both groups were compared using the Copenhagen consensus conference: ease of laryngoscopy, vocal cord position and/or movement, and response to intubation or cuff (cough or diaphragmatic movement). Intubation conditions were considered acceptable (excellent or good) or unacceptable (poor). Systolic, diastolic arterial pressures and heart rate were also recorded during the study. ResultsIn total, 76 patients (38 in each group) were included in this study. Clinically acceptable intubation conditions were significantly more observed in the magnesium group Mg + compared to the saline group Mg-: 36 patients (95 %) vs. 15 patients (39 %) (P < 0.001).Hemodynamic stability was more observed in the magnesium group, with a statistically significant lower heart rate throughout Mg + compared to the saline group. ConclusionAdministration of magnesium sulfate before induction of anesthesia significantly improved intubation conditions without the need for neuromuscular blocking agents.

Efficiency of face mask ventilation before and after neuromuscular blockade: A randomised, double-blind controlled study.

The traditional practice of administrating neuromuscular blocking drugs (NMBDs) after checking face mask ventilation is challenged repeatedly. This study compared the efficiency of face mask ventilation before and after administrating an NMBD in a patient with a normal airway. The secondary outcome measured was the grade of mask ventilation and tracheal intubating conditions. After ethical approval, patients (n = 120) in the age group of 18-65 years scheduled for elective surgery under general anaesthesia were randomly assigned into two groups. Group 1 received an NMBD before checking face mask ventilation. Group 2 received an NMBD after checking face mask ventilation. Lungs were ventilated for 180 s, during which expiratory tidal volume (Vte) was recorded as the primary outcome. Hans's grading for face mask ventilation was used to grade mask ventilation. The ease of intubation was assessed based on intubating conditions (ease of laryngoscopy, vocal cord movement, and limb movement). SPSS 20.0 software was used for statistical analysis. For a total of 180 seconds of mask ventilation, the mean (standard deviation) Vte measured after apnoea was significantly higher in Group 1 versus Group 2 [471.9 (63.3) vs 434.8 (77.0) mL/breath, P = 0.004]. The intubating condition was either excellent or good in all patients. The administration of NMBDs resulted in a larger mask Vte and shorter intubation time.

A Comparative Study between Propofol-fentanyl versus Propofol-suxamethonium for Ease of Endotracheal Intubation in Children.

Following propofol induction, suxamethonium tremendously improves intubating conditions in children and has been the gold standard agent for this purpose. However, suxamethonium could be absolutely contraindicated in some patients. Fentanyl, a short acting opioid, has been investigated as a suitable alternative with varying results. This study compares the ease of tracheal intubation between propofol-suxamethonium (1.5 mg/kg) and propofol-fentanyl (3 mcg/kg) during general anaesthesia among children. In this double-blind randomised controlled study, 84 ASA I or II patients booked for elective surgery under general anaesthesia requiring tracheal intubation were randomised into two groups (F and S). Induction was with propofol 3 mg/kg over 30 s followed by either fentanyl 3 mcg/kg or suxamethonium 1.5 mg/kg. Two minutes later, there was an attempt at intubation and intubating conditions were assessed using Steyn's modification of Helbo-Hansen's score (ease of laryngoscopy, jaw relaxation, coughing, vocal cord position, and limb movement). All patients in both groups had successful intubation at the first attempt. Patients in group S (suxamethonium) had significantly better overall intubating conditions compared to those in group F (fentanyl) (p=0.0001), 85.7% in group S compared to 21.4% in group F had excellent intubation condition. None of the patients in the two groups demonstrated fair or poor intubation condition. A combination of propofol-fentanyl can be used as an alternative to propofol-suxamethonium to ease intubation in paediatric patients.

Anatomical location of the vocal cords in relation to cervical vertebrae, a new predictor of difficult laryngoscopy: A descriptive cross sectional study

Airway management is among the challenges faced by the anaesthesiologists. There are anatomical and clinical factors, which can predict the difficult laryngoscopy. In this study, the aim was to predict the easy and difficult laryngoscopy preoperatively by assessing the anatomy of patient’s head and neck. The objective was to assess the same by using the magnetic resonance imaging films of the neck. The study included 110 adult patients with existing preoperative magnetic resonance imaging scans of neck. Preoperative anaesthetic assessment was done by using the thyromental distance, sternomental distance, body weight, mouth opening, Mallampati classification and head neck movement. The magnetic resonance imaging scans were screened for slices to visualise the vocal cords. A projection line was drawn to determinethe topography of vocal cords in relation to the cervical vertebrae. The ease of laryngoscopy by Cormack-Lehane grade was then correlated with the vertebral level of the vocal cords.The laryngoscopy was difficult in over weight patients (p&amp;#60;0.001) and with smaller thyromental distance. It was also observed that the laryngoscopy was easy (p&amp;#60;0.001), when the topographical location of vocal cords were related to C5 and hard, when they are at the level of C4 and C6 (p&amp;#60;0.001). Magnetic resonance imaging films of neck could be used to evaluate the potential difficult laryngoscopy, preoperatively. It can be used along with the existing bedside tests like determination of thyromental distance, sternomental distance and modified Mallampati classification.

IS CRITICAL CARE MYOPATHY A CONTRAINDICATION FOR SUCCINYLCHOLINE?

TOPIC: Critical Care TYPE: Fellow Case Reports INTRODUCTION: Succinylcholine, a depolarizing muscular blocker, has widespread use for rapid sequence intubation (RSI) in the intensive care unit (ICU), emergency department, and operating room. The advantageous pharmacologic profile includes rapid onset of action (40-60 secs), short duration (6-10 mins), and better intubation conditions such as ease of laryngoscopy and diaphragm inactivation. There are recognized adverse effects including benign manifestations (muscle fasciculations) to life-threatening conditions (acute hyperkalemia and malignant hyperthermia). Scenarios with increased risk include muscular dystrophies, rhabdomyolysis, crush/burn injuries, malignant hyperthermia, and abdominal infections. We present a case of life-threatening hyperkalemia after administration in the setting of critical care myopathy. CASE PRESENTATION: A 63-year-old woman was admitted for acute respiratory distress syndrome from COVID-19 pneumonia. Treatment included steroids, neuromuscular blockade, and prone positioning. Due to frequent ventilator associated pneumonias and difficulty with airway hygiene, endotracheal (ET) tube exchange was planned on hospital day 34. Succinylcholine was utilized given suitable creatinine clearance, normal serum potassium, and sinus rhythm. The removed ET tube had dark, thick, adherent secretions. Less than one minute from administration, telemetry changed to a wide QRS complex and degenerated into pulseless ventricular fibrillation. There was no preceding hypoxemia. The patient received ACLS with defibrillation for recurrent ventricular fibrillation with ROSC. DISCUSSION: Succinylcholine binds to the post-synaptic nicotinic acetylcholine receptor on the motor endplate causing depolarization. Receptor activation triggers efflux of intracellular potassium into the plasma. Receptor upregulation occurs in pathologic conditions including lower motor neuron disorders, immobilization, burns, and muscular dystrophies. Myopathies have inherent membrane fragility and increased permeability producing release of potassium. The development of critical illness myopathy, polyneuropathy, and polyneuromyopathy in the ICU has an incidence of 25-83%. Proposed mechanisms include myosin loss, necrosis of the muscle, muscle membrane dysfunction, denervation of the muscle, nerve ischemia, and axonal injury. Activation of the acetylcholine receptors and sustained muscle contraction in this state can result in devastating hyperkalemia. CONCLUSIONS: Succinylcholine as a paralytic medication for RSI in patients with critical care myopathy should give providers clinical equipoise. There is a risk for acute hyperkalemia due to the damaged muscle membrane and upregulated acetylcholine receptors. REFERENCE #1: Tran, D. T. T., et al. "Rocuronium vs. succinylcholine for rapid sequence intubation: a Cochrane systematic review." Anaesthesia 72.6 (2017): 765-777. REFERENCE #2: Martyn, J. A. Jeevendra, and Martina Richtsfeld. "Succinylcholine-induced hyperkalemia in acquired pathologic statesetiologic factors and molecular mechanisms." Anesthesiology: The Journal of the American Society of Anesthesiologists 104.1 (2006): 158-169. REFERENCE #3: Shepherd, Starane, Ayush Batra, and David P. Lerner. "Review of critical illness myopathy and neuropathy." The Neurohospitalist 7.1 (2017): 41-48. DISCLOSURES: No relevant relationships by Bhupinder Natt, source=Web Response No relevant relationships by Alan Nyquist, source=Web Response

Intubating conditions following four different doses of propofol in children

Background: Day case surgery offers advantages to the patient, the family and the performing institution. Children are excellent candidates since they are generally healthy and often require brief surgical interventions. Day case surgery requires rapid emergence from anaesthesia, minimal delay in recovery and rapid readiness for discharge from the ward. The ideal anaesthetic agents should have rapid onset, short duration, minimal side effects and minimal residual effects. The pharmacodynamics and -kinetics of propofol and alfentanil are well suited for day case surgery and may obviate the need for muscle relaxants. The purpose of our study was to determine the optimal dosing schedules for intubation following propofol combined with alfentanil and sevoflurane anaesthesia while maintaining haemodynamic stability as these dosing schedules still warrant refinement. Methods: We conducted a randomised prospective blinded study in which fifty-nine children (aged 3–10 years) presenting for dental extractions were induced with sevoflurane (in 50% oxygen/nitrous oxide), then received propofol (0.5, 1, 1.5 or 2 mg/kg) and alfentanil (10 μg/kg) to aid intubation. For each dose of propofol, the ease of intubation (assessed by the Helbo-Hansen score) was correlated with blood pressure and pulse rate (prior, during and after intubation) to determine the optimal propofol dosage allowing adequate intubation conditions with the least haemodynamic effects. Results: Overall adequacy of intubating conditions improved significantly (p = 0.0079) as propofol dose increased. Similarly, decrease in vocal cord movement (p = 0.0341), incidence of coughing (p = 0.0379) and limb movement (p = 0.0165) was observed. Ease of laryngoscopy and jaw relaxation did not improve significantly (p = 0.1319 and 0.1971 respectively). Changes in systolic, diastolic and mean arterial pressure as propofol dose increased were not statistically significant. Conclusion: Propofol in a dose of 1.5 to 2 mg/kg (when used in conjunction with alfentanil 10 μg/kg, after sevoflurane induction) allowed adequate intubating conditions whilst maintaining cardiovascular stability. The decrease in blood pressure, although not statistically significant, may become clinically relevant in children with underlying cardiovascular disease. This drug combination seems to be a reasonable means for avoiding the need for muscle relaxation for children who require tracheal intubation for brief surgical procedures.

Efficacy of Dexmedetomidine as an Adjunct in Aiding Video laryngoscope-Assisted Assessment of Vocal Cord Movements at Extubation Following Total Thyroidectomy.

Background:Assessment of vocal cord movements following total thyroidectomy diagnoses recurrent laryngeal nerve injury. Use of videoscope along with sedatives may blunt hemodynamic responses seen with the conduct of direct laryngoscopy for assessing vocal cord mobility.Aims:The primary objective of this study was to assess changes in mean arterial pressure (MAP) during vocal cord assessment following total thyroidectomy using video laryngoscope, with and without the use of dexmedetomidine as an adjunct. Secondary objectives included assessment of changes in heart rate (HR), patient reactivity score along with ease of laryngoscopy and vocal cord visibility.Settings and Design:This randomized, prospective, unblinded study was conducted in 54 patients at a tertiary care center.Materials and Methods:Group D received dexmedetomidine 0.5 μg/kg, once the thyroid was removed. Group S did not receive dexmedetomidine. Hemodynamic response at extubation, patient reactivity, ease of laryngoscopy, and ease of vocal cord assessment were noted.Statistical Analysis Used:Chi-square test and Independent t-test.Results:Baseline HR, systolic blood pressure (SBP), and MAP were comparable between the groups. However subsequently, Group D had significantly lower HR and SBP at the time of extubation and at 3 and 6 min later. MAP at extubation and at 3 min later was comparable, but at 6 min, Group D had significantly lower values. In both groups, patient reactivity scores, ease of laryngoscopy, and vocal cord visibility were comparable (P > 0.05).Conclusion:Dexmedetomidine 0.5 μg/kg when used as an adjunct clinically improved conditions for assessing vocal cord mobility with significant attenuation of associated hemodynamic responses.

Assessment of Intubating Conditions with Different Doses of Propofol without Muscle Relaxant in Children

Background: The aim of our study was to assess of tracheal intubation by different doses of propofol preceded by fentanyl for successful tracheal intubation and to see its effectiveness in blunting pressors response in children aged 2-10 years. Methods: This prospective, blind, randomized study was conducted on 120 ASA grade I and II children, between 2 and 10 years undergoing elective surgery who were divided into three groups. The children received different doses of propofol (group I, 2.5 mg/kg; group II, 3.0 mg/kg; and group III, 3.5 mg/kg) preceded by a fixed dose of fentanyl (2 μg/kg) 5 min earlier. The tracheal intubating conditions were graded based on scoring system devised by Helbo-Hensen et al. with Steyn modification which includes five criteria; ease of laryngoscopy, degree of coughing, position of vocal cords, jaw relaxation, and limb movement and graded on a 4-point scale. Heart rate (HR) and mean arterial pressure (MAP) changes were also noted. Results: Tracheal intubating conditions were acceptable in 65% of the patients in group I, while significantly higher (P<0.001) in group II (97.5%) and in group III (100%). The pressor response was not effectively blunted in group I (17% increases in HR), while effectively blunted in groups II and III. A fall in hemodynamic was seen in group III indicated by a decrease in MAP (16%) and HR (11%). No airway complications were noted. Conclusions: Propofol 3.5 mg/kg (group III) preceded by fentanyl 2 μg/kg is the excellent dose combination in our study. It provides acceptable intubating conditions in 100% patients, blunts pressor response to intubation without significant cardiovascular depression.

Endotracheal intubation without muscle relaxants in children using remifentanil and propofol: Comparative study.

Introduction:Endotracheal intubation is essential during general anesthesia and muscle relaxant drugs provide ideal conditions for this purpose. The objective of this study was to evaluate the intubating condition of remifentanil combined with propofol without muscle relaxant.Materials and Methods:In this prospective randomized study, 60 children aged 3-12 years, American Society of Anesthesiologists physical status I and II were included. All the children were premedicated with 0.05 mg/kg midazolam and 1.5 mg/kg lidocaine 5 min before the induction of anesthesia with 3 mg/kg propofol. Then, they were allocated randomly to receive either 2 μg/kg remifentanil (group R) or 1.5 mg/kg succinylcholine (group S). Tracheal intubation was attempted 90 s after the administration of propofol. The quality of intubation was assessed by using Copenhagen score based on jaw relaxation, ease of laryngoscopy, position of vocal cord, coughing and limb movement. Heart rate and blood pressure were recorded before and after induction, and 1, 3, 5 min after intubation.Results:There was no significant difference in intubating condition between the two groups (P = 0.11). Intubation condition was excellent in 26 of 30 (86.7%) patients in the group R compared with 30 (100%) patients in the group S. We observed significant difference in heart rate and systolic blood pressure over time between two groups (P = 0.02, P = 0.03 respectively). After intubation, we had higher heart rate and systolic blood pressure with a significant difference in group S compared with group R (P = 0.006, P = 0.018). None of the children had a chest rigidity, laryngospasm, and hypoxia.Conclusions:In premedicated children, propofol-remifentanil combination provides adequate conditions for tracheal intubation that is comparable with succinylcholine. Hemodynamic response to laryngoscopy and tracheal intubation was controlled better in group R.

Continuous infusion of remifentanil combined with target-controlled infusion of propofol for tracheal intubation in dogs

Ninety dogs presenting for elective surgery were randomly assigned into three groups of 30. Intubation conditions, haemodynamic responses and other events were evaluated following target controlled infusion (TCI) with propofol...

Evaluation of endotracheal intubating conditions without the use of muscle relaxants following induction with propofol and sevoflurane in pediatric cleft lip and palate surgeries.

Background and Aims:Children with facial clefts are usually difficult to intubate and it is considered safer to keep them spontaneously breathing while securing the airway. This prospective comparative study was conducted to evaluate endotracheal intubating conditions in pediatric patients undergoing cleft surgeries, without the use of muscle relaxants following induction with propofol and sevoflurane.Materials and Methods:Sixty patients aged 1month to 3 years, were randomly allocated into two equal groups. Anesthesia was induced with sevoflurane 8% in oxygen in group 1 and with propofol 3 mg/kg in group 2. Laryngoscopy and intubation were attempted 150 s after induction in both groups and ease of laryngoscopy, position of vocal cords, degree of coughing, jaw relaxation, and limb movements were assessed and scored. Total score of 5 was considered excellent, 6-10 good, 11-15 poor, and 16-20 bad. Total score ≤ 10 was considered clinically acceptable, and >10 as clinically unacceptable. Chi-square and Wilcoxon Mann-Whitney tests were used to analyze data.Results:There was no significant difference between groups when ease of laryngoscopy was compared. Sevoflurane induced patients had significantly better position of vocal cords at intubation and the propofol group had significantly more episodes of coughing. Significantly less number of patients had limb movements in sevoflurane group. There was no significant difference in degree of jaw relaxation between groups. The sevoflurane group had significantly better total scores and clinically acceptable intubating conditions.Conclusion:Sevoflurane 8% in oxygen provides clinically acceptable intubating conditions without use of muscle relaxants in pediatric cleft patients.

Magnesium sulphate

Tracheal intubation without administration of a neuromuscular blocking drug is used frequently in anaesthesia. Several techniques and adjuvants have been tried to improve intubating conditions. Magnesium sulphate is an agent with analgesic, anaesthetic and muscle relaxant effects. To assess the effect of magnesium sulphate on intubating conditions after induction of anaesthesia without a neuromuscular blocking drug. Double-blinded randomised study. Sixty patients with American Society of Anesthesiologists physical status 1/2 scheduled for elective surgery under general anaesthesia were included. Avicenna Military Hospital between June 2010 and March 2011. Before induction of general anaesthesia, patients were assigned to receive either a 10-min infusion of magnesium sulphate 45 mg kg(-1) in 100 ml of isotonic saline (magnesium group, n = 30) or the same volume of saline (control group, n = 30). Anaesthesia was induced with fentanyl 3 μg kg(-1) followed 3 min later by propofol 2.5 mg kg(-1). Intubating conditions were evaluated by a blinded anaesthesiologist using the criteria of the Copenhagen consensus conference: ease of laryngoscopy, vocal cord position and/or movement and response to intubation or cuff inflation (cough or diaphragmatic movement). Intubating conditions were considered as acceptable (excellent or good) or unacceptable (poor). Mean arterial pressure and heart rate were also recorded during the study period. The two groups were comparable in their demographic profiles. Clinically acceptable intubating conditions were observed more frequently in the magnesium group than in the control group: 25 (83%) vs. 18 patients (60%) (P = 0.042). There was no failed intubation. There were no differences between the groups with regard to haemodynamic variables. Addition of magnesium sulphate to propofol and fentanyl at induction of anaesthesia significantly improved intubating conditions without administration of a neuromuscular blocking drug.

Tracheal Intubation Without the Use of Neuromuscular Blocking Agents

Dear Editor, I read with keen interest the article by Imani et al. (1) in which the authors compare tracheal intubating conditions following intravenous (IV) administration of remifentanil 5 μg/kg or alfentanil 50 μg/kg followed by induction of anesthesia with propofol 2 mg/kg in 100 adult patients premedicated with IV midazolam 1 mg. Intubating conditions were assessed (scoring 1 to 4) by ease of laryngoscopy, patency of vocal cords, jaw relaxation, and limb movement. Airway reaction to tracheal intubation is an important consideration while assessing intubating conditions. Viby-Mogensen et al. (2) describe a qualitative scoring system graded as excellent, good or poor, respectively, comprising of five variables: Laryngoscopy (easy, fair, difficult) Vocal cord position (abducted, intermediate, closed) Vocal cord movement (none, moving, closing) Coughing (none, diaphragmatic, sustained, > 20 s) Movement of the limbs (none, slight, vigorous) Intubating conditions are regarded as excellent (all qualities are excellent), good (all qualities are either excellent or good), and poor (the presence of a single quality listed under poor) (2). They further regard excellent or good intubating conditions as clinically acceptable; and poor intubating conditions as clinically not acceptable. It would be interesting to compare the two narcotic regimens (remifentanil vs. alfentanil) for tracheal intubation without neuromuscular blocking agents (NMBAs) with regard to the incidence of coughing. Tracheal intubation is associated with hemodynamic changes. In this regard, the use of remifentanil 5 μg/kg would be expected to cause significant hypotension and/or bradycardia. It would be useful to know the incidence of hypotension or bradycardia and also if there was need for administration of vasopressors or atropine. I am intrigued by two statements in the article that are in contradistinction: The combination of remifentanil with propofol may also be advantageous in cases of long and difficult intubation, wherein it may not only be possible to inspect the airway with the laryngoscope. Thus, this method is best avoided in patients with high Mallampati grades or airway difficulties. The technique of tracheal intubation without the use of NMBAs enables us to assess the airway by laryngoscopy. This technique may be useful in cases of both predicted and unexpected difficult intubation, in cases where NMBAs are either contraindicated (e.g. myopathies) or not required to facilitate surgical access (3).

Comparison of intubating conditions following administration of low-dose rocuronium or succinylcholine in adults: A randomized double blind study.

Context:Though rocuronium has a rapid onset of neuromuscular blockade like succinylcholine without the latter's adverse effects, its use is limited due to its prolonged action.Aim:Aim was to evaluate whether reducing the intubating dose of rocuronium shortens its duration of action, yet provides clinically acceptable intubating conditions.Settings and Design:tt was a prospective, randomized, and double blind trial.Materials and Methods:100 American Society of Anaesthesiologists Physical Status (ASAPS) I or II patients aged between 18–65 years scheduled for elective surgery were randomly allotted one of the four rocuronium groups (rocuronium dose of 0.3 mg/kg intubated at 60 s or at 90 s, rocuronium 0.6 mg/kg intubated at 60 s or at 90 s) orsuccinylcholine group (succinylcholine 1.0 mg/kg intubated at 60 s) and intubating conditions were assessed with: Ease of laryngoscopy, vocal cord position, and reaction to insertion of tracheal tube and cuff inflation.Statistical Analysis:Statistical tests used were analysis of variance (ANOVA), Chi-Square test, Repeated measures of ANOVA and Mann–Whitney U test.Results:Rocuronium in dosage of 0.3 mg/kg gaveclinically acceptable intubating conditions in 35% and 60% subjects at 60 s or 90 s, respectively, whereas in dosage of 0.6 mg/kg, intubating conditions were acceptable in 80% and 100% subjects intubated at 60 s and 90 s.Conclusion:Rocuronium in dose of 0.3 mg/kg does not give clinically acceptable intubating conditions at 60 or 90 s but has shorter duration of action. Rocuronium in dose of 0.6 mg/kg gives clinically acceptable intubating conditions at 60 or 90 s, comparable to succinylcholine 1 mg/kg.

Forces applied to the maxillary incisors by video laryngoscopes and the Macintosh laryngoscope

Modern video laryngoscopes (VLSs) provide a superior view of the glottis, facilitating easier intubations. This study evaluates the forces applied to the maxillary incisors when using various VLSs and a Macintosh blade. Fifty consecutive surgery patients were randomly assigned to receive laryngoscopy from a pair of four blades investigated in the study - the VLS GlideScope(®) (Verathon Inc., Bothell, WA, USA), V-Mac™ Storz(®) (Karl Storz, Tuttlingen, Germany), and McGrath™ (Aircraft Medical, Edinburgh, United Kingdom); and the classic Macintosh blade also from Storz(®) (Karl Storz). An endotracheal tube (ETT) was brought into position anterior to the vocal cords, with actual intubation carried out only with the second of the laryngoscopes. Sensors measured the forces directly applied to the patient's maxillary incisors while inserting the ETT. Other common metrics of intubation difficulty (e.g. Mallampati grade, Cormack-Lehane grade, and time) were also recorded. Only one patient was not intubated within the standard study parameters and was converted to the hospital protocols for difficult intubations. The forces applied to the maxillary incisors were significantly greater with the Macintosh blade compared with all VLSs. There were no differences between the VLSs with regard to the forces. Patient characteristics, including Mallampati grade, were not predictive of the forces applied. All VLSs considered were safer for the patient than was the Macintosh blade in terms of the forces applied to the maxillary teeth, time, number of insertion attempts, and view achieved of the glottic arch. There is a small, but significant, difference in the time and number of insertion attempts required during laryngoscopy with the different VLSs. There was no difference in the forces applied. The geometry of the respective blades may be an important component in the ease of laryngoscopy.

Induction of tracheal intubation without muscle relaxant by target controlled infusion of propofol combined with remifentanil in children

To observe the safety and feasibility of tracheal intubation by target-controlled infusion of propofol and remifentanil without muscle relaxant in children. Totally 100 4-10-year-old pediatric patients (ASA1) who had been scheduled for plastic surgery were equally divided into remifentanil group and control group through computer-generated randomized grouping. In all patients, five minutes after intravenous administration of atropine 0.01 mg/kg and midazolam 0.1 mg/kg, propofol was infused at the targeted effect-site concentration (Ce of 6 μg/ml. When the intended target Ce of propofol was reached, the remifentanil group began to be infused with remifentanil at a Ce of 5 ng/ml, and normal saline (0.1 ml/kg) was injected simultaneously. In the control group remifentanil was replaced by normal saline and rocuronium (0.8 mg/kg) was injected together with the normal saline. After the equilibration of plasma and the Ce of remifentanil were reached, tracheal intubation was attempted. The complications during the induction and tracheal intubation were recorded. The intubating conditions were assessed using a five-point scoring system based on ease of laryngoscopy, vocal cords position, coughing, jaw relaxation and limb movement. The success rate of tracheal intubation was in 90% in remifentanil group and 98% in the control group (P=0.122).CONCLUSION Target-controlled infusion of propofol and remifentanil at Ce of 6 μg/ml and 5 ng/ml is feasible for the induction and tracheal intubation without muscle relaxant in children.

Comparison of pharmacodynamics and circulatory function of domestic and imported rocuronium

Objective To compare the phaimacodynamics and circulatory function of domestic and imported rocuronium. Methods This is a five center study of rocuronium. Two hundred and ten ASA Ⅰ or Ⅱ patients aged 18-65 yr undergoing elective surgery under general anesthesia were randomly divided into 2 groups (n = 105 each): domestic rocuronium group (group Ⅰ ) and imported rocuronium group (group Ⅱ ) . Anesthesia was induced and maintained with TCI of propofol (target plasma concentration = 3 mg/L) and remifentanil (target effect-site concentration = 2-4 μg/L) . Tracheal intubation was facilitated with intravenous rocuronium 0.6 mg/kg. The N-M function was assessed by accelerography (TOF-Watch(R) SX, Organon, Netherlands) using TOF stimulation of ulnar nerve. Onset time, clinical duration, 75% recovery time,recovery indexes, the extent of maximal NM blockade and intubation conditions (ease of laryngoscopy, position of vocal cords and airway reaction) were monitored and recorded. BP and HR were also recorded. Results There were no significant differences in the onset time, clinical duration, recovery indexes, the extent of maximal N-M blockade, the intubation conditions, BP, HR and adverse reactions between groups Ⅰ and Ⅱ ( P ＞ 0.05) . The 75% recovery time was significantly longer in group Ⅱ than in group Ⅰ (P ＜ 0.05＝. Conclusion The pharmacodynamics of domestic and imported rocuronium is comparable. The two drugs have no adverse effect on the circulatory function. Key words: Androstanols; Neuromuscular blockade; Dose-response relationship, drug; Blood circulation

Effect of intravenous lidocaine on efficacy of sevoflurane combined with remifentanil for tracheal intubation without neuromuscular relaxants

Objective To investigate the effect of intravenous lidocaine on the efficacy of sevoflurane combined with remifentanil for tracheal intubation without neuromuscular relaxants. Methods Seventy-five ASA Ⅰor Ⅱ patients, aged 18-64 yr, scheduled for elective surgery, needing tracheal intubation under general anesthesia, were randomly divided into 3 groups ( n = 25 each) : sevoflurane + remifentanil 1 μg/kg group (group A) ;sevoflurane + remifentanil 1 μg/kg + lidocaine 1 mg/kg group (group B); sevoflurane + remifentanil 2 μg/kg group (group C) . Two minutes after inhalation of 8% sevoflurane for anesthesia induction, remifentanil 1 μg/kg, remifentanil 1 μg/kg + lidocaine 1 mg/kg, and remifentanil 2 μg/kg were injected intravenously in groups A, B and C respectively. Tracheal intubation was performed after completion of remifentanil injection. Intubating conditions were assessed based on ease of laryngoscopy, position of vocal cords, activity of vocal cords, degree of coughing and limb movement. MAP and HR were also recorded before induction and immediately before and after intubation. Results Tracheal intubations were successful in all patients. The satisfactory rates of coughing were significantly higher in groups B and C, and MAP and HR were significantly lower immediately before and after intubation in group C than in group A ( P ＜ 0.05) . The satisfactory rate of coughing was significantly higher in group B than in group C ( P ＜ 0.05) . During intubation, 3 cases developed hypotension and 1 case bradycardia in group C. Conclusion When sevoflurane combined with remifentanil is used for tracheal intubation without neuromuscular relaxants, intravenous lidocaine 1 mg/kg can not only improve intubating conditions, but also decrease the consumption of remifentanil. Key words: Lidocaine; Piperidines; Intubation,intratracheal; Sevoflurane

Propofol 2 mg/kg is superior to propofol 1 mg/kg for tracheal intubation in children during sevoflurane induction

Propofol has been used to facilitate tracheal intubation within a short time of sevoflurane induction without a muscle relaxant in children. We compared as the primary outcome the incidence of excellent intubating conditions after 8% sevoflurane and propofol 1 or 2 mg/kg. One hundred and four patients (2-7 years) were randomly assigned to receive propofol 1 mg/kg in group SP1 (n=53) or propofol 2 mg/kg in group SP2 (n=51) after inhalation induction using sevoflurane 8% in oxygen. Forty-five seconds after propofol and controlled ventilation, intubating conditions were assessed using a four-point scoring system based on ease of laryngoscopy, vocal cords position, coughing, jaw relaxation and limb movement. Heart rate and systolic blood pressure were measured as baseline, after sevoflurane induction, propofol, intubation and at 2 and 5 min following intubation. Three patients in group SP1 were excluded from analysis. Time from sevoflurane induction to intubation (248.9±71.3 s in group SP1 vs. 230.9±61.3 s in group SP2) and endtidal sevoflurane before intubation (5.6±1.6% in group SP1 vs. 5.2±1.5% in group SP2) did not differ between the two groups. The incidence of excellent intubating conditions was significantly higher in group SP2 compared with group SP1 [47/51 (92%) vs. 28/50 (56%)]. The incidence of acceptable intubating conditions was significantly higher in group SP2 compared with group SP1 [48/51 (94%) vs. 35/50 (70%)]. No hemodynamic difference was noted at any time point between the two groups. Propofol 2 mg/kg during 8% sevoflurane induction resulted in a higher proportion of excellent intubating conditions compared with propofol 1 mg/kg.

Validation of a model of graded difficulty in Laerdal SimMan: functional comparisons between Macintosh, Truview EVO2, Glidescope Video Laryngoscope and Airtraq

A randomised, cross-over study was designed to validate a new model of graded difficulty (based on mandibular space reduction) in the Laerdal 'SimMan' mannnequin and to suggest functional comparisons between Macintosh. Glidescope Video Laryngoscope, Truview EVO2 and Airtraq. Twenty anaesthetists attempted intubation with all four laryngoscopes in three settings: easy, intermediate (based on a custom-made removable prosthetic insert) and difficult ('tongue oedema', a mannnequin feature). Laryngoscopic view and time to intubate were the primary outcome measures. Other measures were successful intubation, ease of laryngoscopy [visual analogue scale (VAS)] and intubation (VAS), tongue compression score and number of attempts. Between settings comparisons demonstrated that Macintosh, Glidescope and Airtraq had worsening scores from easy to intermediate with lesser changes for Truview. However, with the intermediate to difficult comparison, Airtraq was the only blade with no worsening of scores. Within-blade comparisons showed that Macintosh was superior over all in both the easy and intermediate settings, whereas Airtraq was the most successful blade in the difficult setting. Our study suggests that Glidescope and, to some extent Truview, are functionally similar to Macintosh and suffer from similar limitations in the difficult setting. On the contrary, Airtraq was functionally unique in providing good laryngeal exposure in the difficult setting and without excessive tongue compression.