Routine Induction Of Anesthesia Research Articles

Airway Management of Intracranial Aneurysms Associated with Nasopharyngolaryngeal Hemangioma: A Case Report

Intracranial aneurysm is a very common disease, which is an abnormal bulge on the wall of intracranial artery. It is the first cause of subarachnoid hemorrhage. With the development of imaging, the disease is easily diagnosed. A 60-year-old man was diagnosed with anterior communicating artery aneurysm and underwent aneurysm clipping. During routine induction of anesthesia, a nasopharyngolaryngeal hemangioma was visualized under a video laryngoscope. This poses a serious challenge for tracheal intubation. With the assistance of a video laryngoscope and local anesthesia with lidocaine, a 6.5# reinforced endotracheal tube was inserted. Nasopharyngolaryngeal hemangioma is a congenital vascular anomaly characterized by proliferation of endothelial cells. The incidence of infantile and childhood hemangiomas is low, and most spontaneously resolve by the age of 4 to 6 years. Adult nasopharyngolaryngeal hemangioma are extremely rare and are residual lesions from infancy and childhood. Although nasopharyngolaryngeal hemangioma does not clearly affect the quality of life of patients, intracranial hemangioma has caused blurred vision and decreased vision. Therefore, surgery for intracranial aneurysm was necessary for this patient. This case emphasizes the management of unplanned difficult airway of pharyngeal hemangioma and the emergency plan for hemangioma rupture and bleeding. Provide guidance and risk management procedures for nasopharyngotracheal intubation.

Comparison of double lumen tube insertion using the McGrath MAC versus direct laryngoscopy in adult patients with a limited glottis view: A prospective interventional study.

Passage of double-lumen tubes (DLT) can be challenging in patients with limited glottis view. This study aims to determine the usefulness of McGrath® MAC videolaryngoscope (VL) in cases with limited glottis view on direct laryngoscopy with Macintosh blade. After study approval and registration of trial, consent was sought from all adult patients planned for elective DLT insertion for lung isolation during the course of general anesthesia. Patients not consenting, less than 18 years, with anticipated difficult mask ventilation or need for rapid sequence induction were excluded. Following routine anesthetic induction, laryngoscopy was attempted by an experienced anesthesiologist using Macintosh scope. If the view obtained was Cormack and Lehane (CL) view IIB and above or the attempt at intubation using DLT failed despite a CL I/IIA view, the patient was included in the trial. The laryngoscope was removed and after ensuring adequate oxygenation and depth of anesthesia, intubation was attempted using McGrath® MAC VL. The percentage of glottis opening (POGO) score was noted for both the scopes. DLT insertion was attempted in 76 patients in the study period. Eight patients were included in the trial on account of limited glottis view/failure with Macintosh scope. Insertion of DLT with McGrath MAC was tried only in six patients, in two patients, the VL was not available for use. The mean (standard deviation) POGO score with Macintosh scope was 9 (±20), which significantly improved with the use of VL to 71 (±24), P = 0.01. McGrath MAC is helpful in inserting DLT in patients with limited glottis view with Macintosh scope.

External Validation of a Pharmacokinetic Model of Propofol for Target-Controlled Infusion in Children under Two Years Old.

BackgroundPreviously, a linked pharmacokinetic-pharmacodynamic model (the Kim model) of propofol with concurrent infusion of remifentanil was developed for children aged 2–12 years. There are few options for pharmacokinetic-pharmacodynamic model of propofol for children under two years old. We performed an external validation of the Kim model for children under two years old to evaluate whether the model is applicable to this age group.MethodsTwenty-four children were enrolled. After routine anesthetic induction, a continuous infusion of 2% propofol and remifentanil was commenced using the Kim model. The target effect-site concentration of propofol was set as 2, 3, 4, and 5 μg/mL, followed by arterial blood sampling after 10 min of each equilibrium. Population estimates of four parameters—pooled bias, inaccuracy, divergence, and wobble—were used to evaluate the performance of the Kim model.ResultsA total of 95 plasma concentrations were used for evaluation of the Kim model. The population estimate (95% confidence interval) of bias was −0.96% (−8.45%, 6.54%) and that of inaccuracy was 21.0% (15.0%–27.0%) for the plasma concentration of propofol.ConclusionThe pooled bias and inaccuracy of the pharmacokinetic predictions are clinically acceptable. Therefore, our external validation of the Kim model indicated that the model can be applicable to target-controlled infusion of propofol in children younger than 2 years, with the recommended use of actual bispectral index monitoring in clinical settings that remifentanil is present.Trial RegistrationClinical Research Information Service Identifier: KCT0001752

Effect of Dexmedetomidine Hydrochloride on Early Cognitive Function in Postoperative Elderly Patients

Purpose: to explore the effect of dexmedetomidine hydrochloride on early cognitive function in postoperative elderly patients. Methods: during December 2015 to November 2016, 80 elderly patients who received surgical treatment in our hospital were selected as research object. Result: patients were randomly divided into two groups (control group and research group). On the basis of routine anesthetic induction, patients in research group took dexmedetomidine, in comparison, patients in control group took an equal dose of sodium chloride solution. The goal was to evaluate the anesthetic effect of those two methods. One hour before surgery, there was no significant difference in the MMSE score between the two groups (P＞0.05). In research group, the MMSE scores at postoperative 1d and 3d were (23.8 ± 2.4) and (27.1 ± 2.0) respectively. In control group, the MMSE scores at postoperative 1d and 3d were (20.5 ± 3.2) and (24.6 ± 3.4) respectively. The difference was statistically significant (P＜0.05). There was no significant difference in anesthesia time, awake time and extubation time between those two groups (P＞0.05). Conclusion: using dexmedetomidine in elderly patients after surgery can protect early cognitive function and improve the prognosis.

Effects of different anesthetic methods on postoperative acute pain in patients with myasthenia gravis undergoing video-assisted thoracoscopic thymectomy

Objective To evaluate the effects of different anesthetic methods on postoperative acute pain in patients with myasthenia gravis undergoing video-assisted thoracoscopic thymectomy. Methods Fifty-four patients of both sexes, aged 18-64 yr, with body mass index of 20-28 kg/m2, of American Society of Anesthesiologists physical statusⅠor Ⅱ, scheduled for elective video-assisted thoracoscopic thymectomy, were allocated into 2 groups (n=27 each) using a random number table method: sevoflurane-based anesthesia group (group S) and propofol-based anesthesia group (group P). After routine anesthesia induction in two groups, anesthesia was maintained by inhaling sevoflurane and target-controlled infusion of remifentanil in group S and by target-controlled infusion of propofol and remifentanil in group P. Heart rate and mean arterial pressure were recorded before operation and at 5 and 10 min after extubation (T1, 2). The intensity of pain at T2 and visual analog scale (VAS) score and consumption of morphine at 1, 2, 4, 24 and 48 h after operation (T3-7) were recorded.The pressing times of analgesia pump, requirement for rescue analgesia and development of nausea and vomiting were recorded at T7. Results There were no significant differences in heart rate or mean arterial pressure at each time point between two groups (P>0.05). Compared with group S, the intensity of pain was significantly alleviated at T2, and VAS scores and morphine consumption were decreased at T3, 4 in group P (P 0.05). Conclusion Propofol-based anesthesia provides better efficacy in alleviating postoperative acute pain in patients with myasthenia gravis undergoing video-assisted thoracoscopic thymectomy. Key words: Propofol; Anesthetics, inhalation; Pain postoperative; Myasthenia gravis; Thoracoscopy; Thymectomy

Quantifying the rambunctious journey of the anesthesia provider's hands during simulated, routine care

The role of anesthesia providers in dispersing potentially pathogenic material from one patient to another during intraoperative care needs further study. In this study we aimed (1) to quantify the dispersion of a surrogate pathogen from a simulated patient's mouth to the anesthesia workstation during routine anesthetic induction, (2) to test the hypothesis that there would be fewer contamination sites by providers who used a double-gloving technique, and (3) to examine the effectiveness of between-case anesthesia apparatus disinfection. Twenty subjects were randomized to a single pair of gloves group (group 1) or a double-gloved group (group 2) and completed a simulated general anesthesia induction, completing a standardized set of interventions. Dispersion of a surrogate pathogen dye placed in the oral cavity of the simulated patient was tracked by a blinded observer and photography. Standard cleaning of the workstation was performed, and residual dye was quantified. Group performance was plotted using regression analysis and rate of contamination compared using parametric statistics. Group 1 contaminated an average of 16.0 (SEM = 0.89) sites compared with group 2, who contaminated an average of 7.6 (SEM = 0.85). The cart drawers, gas flow dials, medication vials, and ventilator controls were significantly contaminated by group 1, but not by group 2 (P < .05 in all cases). There were similar rates of contamination in both groups for the airway equipment, breathing system, intravenous access ports, and the roll of tape used to secure the endotracheal tube. Once the airway management phase of the induction ended, new site contamination continued at a high rate in group 1 but not group 2. A double-gloving technique was associated with less spread of an oral inoculum to the workstation but was not uniformly protective. Between-case cleaning was ineffective in removing the contaminant, indicating that biologic material from one patient may be present when subsequent patients are cared for. This suggests risks for the current patient (eg, skin or oral site transfer to an intravenous site) and also may place future patients at risk. Importantly, using models that simulate actual clinical events can inform clinical practice and decipher challenging areas of ergonomics.

Effect of dexmedetomidine on quality of recovery from sevoflurane-based anesthesia in patients undergoing abdominal surgery

Objective To evaluate the effect of dexmedetomidine on the quality of recovery from sevoflurane-based anesthesia in the patients undergoing abdominal surgery. Methods Eighty patients of both sexes, aged 30-64 yr, weighing 45-80 kg, with American Society of Anesthesiologists physical status Ⅰ or Ⅱ, scheduled for elective abdominal surgery, were randomly assigned into 2 groups(n=40 each)using a random number table: control group(group C)and dexmedetomidine group(group D). After routine induction of anesthesia, all the patients were tracheally intubated, and mechanically ventilated.Anesthesia was maintained with sevoflurane inhalation and intermittent iv boluses of sufentanil and cisatracurium besylate, and bispectral index values were maintained at 45-60.After induction of anesthesia, dexmedetomidine was infused in a dose of 1 μg/kg over 15 min, followed by a continuous infusion of 0.6 μg·kg-1·h-1 until 30 min before the end of surgery in group D. Group C received normal saline instead.Heart rate(HR)and mean arterial pressure(MAP)were recorded at the end of surgery, and at 1 min before and after extubation.The emergence time, extubation time, and occurrence of bucking during extubation, and nausea and vomiting, respiratory depression, and agitation during recovery from anesthesia were recorded. Results Compared with group C, MAP and HR were significantly decreased at 1 min before and after extubation, the emergence time and extubation time were shortened, the incidence of bucking, nausea and vomiting, and agitation was decreased, and no significant change was found in the incidence of respiratory depression in group D. Conclusion Dexmedetomidine infused in a dose of 1 μg/kg after routine induction of anesthesia, followed by a continuous infusion of 0.6 μg·kg-1·h-1 until 30 min before the end of surgery, can significantly increase the quality of recovery from sevoflurane-based anesthesia in the patients undergoing abdominal surgery. Key words: Dexmedetomidine; Anesthetics, inhalation; Anesthesia recovery period; Laparotomy

A Comparison of the Effects of Different Types of Laryngoscope on the Cervical Motions: Randomized Clinical Trial

The rate of cervical injury among all trauma patients is 3.1%. The most important point during intubation of those patients is not to increase the cervical injury. In this study, we hypothesize that there will be a minimal cervical extension during a laryngoscopy with the use of optical view laryngoscopes. Prospective, randomized clinical trial. One hundred and fifty adult patients with ASA physical status I to III were enrolled in our study. After routine anesthesia induction, we randomly assigned the patients into three groups according to the type of laryngoscope. Macintosh type, Truview EVO2(®) type and Airtraq® type laryngoscopes were used in Group DL (n=50), Group TW (n=50) and Group ATQ (n=50), respectively. After applying general anesthesia induction and mask ventilation, all of the patients were positioned in the neutral position. An inclinometer was placed on the forehead of the patients. Then, the extension angle during intubation and the Cormack-Lehane Score were measured and the time to intubation was recorded. One of the 50 patients in the DL Group, 2 of the 50 patients in the TW Group, and 4 of the 50 patients in the ATQ Group were excluded from the study because of the failure of intubation at defined times. The angle of cervical extension during laryngoscopy was found to be 27.24±6.71, 18.08±7.53, and 14.54±4.09 degrees in the Groups DL, TV and ATQ, respectively; these differences also had statistical significance (p=0.000). The duration of intubation was found to be 13.59±5.49, 23.60±15.23, and 29.80±13.82 seconds in Groups DL, TV and ATQ, respectively (p=0.000). A minimal cervical motion was obtained during tracheal intubation with the use of Truview EVO2® and Airtraq® types of laryngoscope compared with the Macintosh laryngoscope. (ClinicalTrials.gov Identifier: NCT02191904).

Effect of dexmedetomidine on intestinal mucosal injury in patients undergoing cardiac valve replacement with CPB

Objective To evaluate the effect of dexmedetomidine on the intestinal mucosal injury in the patients undergoing cardiac valve replacement with cardiopulmonary bypass (CPB). Methods Forty patients of both sexes with rheumatic heart disease, aged 32-64 yr, weighing 40-75 kg, of ASA physical status Ⅱ or Ⅲ(NYHA class Ⅱ or Ⅲ), scheduled for elective cardiac valve replacement with CPB, were randomly divided into 2 groups (n=20 each) using a random number table: control group (group C) and dexmedetomidine group (group D). After induction of anesthesia, the patients were endotracheally intubated and mechanically ventilated. Anesthesia was maintained with 0.8%-2.0% sevoflurane inhalation and intermittent iv boluses of sufentanil 0.5-1.0 μg/kg and vecuronium 0.04-0.06 mg/kg. Before routine induction of anesthesia, a loading dose of dexmedetomidine 1 μg/kg was injected intravenously over 10 min, followed by continuous infusion at 0.3 μg·kg-1·h-1 until the end of surgery in group D, while the equal volume of normal saline was given in group C. Before CPB, at 30 min after aortic clamping, at the termination of CPB, at the end of surgery and at 6 and 24 h after surgery, central venous blood samples were taken for determination of concentrations of tumor necrosis factor-alpha, interleukin-6(IL-6) and IL-10 and intestinal fatty acid binding protein in plasma (by ELISA), and the plasma concentration of endotoxin (using turbidimetry). The time of postoperative mechanical ventilation and duration of ICU stay were recorded. Results Compared with group C, the concentrations of tumor necrosis factor-alpha, IL-6, IL-10 and endotoxin and intestinal fatty acid binding protein in plasma were significantly decreased, and the time of postoperative mechanical ventilation and duration of ICU stay were shortened in group D. Conclusion Dexmedetomidine infused continuously at 0.3 μg·kg-1·h-1(until the end of surgery) after a loading dose of 1 μg/kg before routine induction of anesthesia can reduce intestinal mucosal injury in the patients undergoing cardiac valve replacement with CPB. Key words: Dexmedetomidine; Cardiopulmonary bypass; Intestinal mucosa; Heart valve prosthesis implantation

A randomised, controlled crossover comparison of the C-MAC videolaryngoscope with direct laryngoscopy in 150 patients during routine induction of anaesthesia

BackgroundThe C-MAC® (Karl Storz, Tuttlingen, Germany) has recently been introduced as a new device for videolaryngoscopy guided intubation. The purpose of the present study was to compare for the first time the C-MAC with conventional direct laryngoscopy in 150 patients during routine induction of anaesthesia.MethodsAfter approval of the institutional review board and written informed consent, 150 patients (ASA I-III) with general anaesthesia were enrolled. Computer-based open crossover randomisation was used to determine the sequence of the three laryngoscopies: Conventional direct laryngoscopy (HEINE Macintosh classic, Herrsching, Germany; blade sizes 3 or 4; DL group), C-MAC size 3 (C-MAC3 group) and C-MAC size 4 (C-MAC4 group) videolaryngoscopy, respectively. After 50 patients, laryngoscopy technique in the C-MAC4 group was changed to the straight blade technique described by Miller (C-MAC4/SBT).ResultsIncluding all 150 patients (70 male, aged (median [range]) 53 [20-82] years, 80 [48-179] kg), there was no difference of glottic view between DL, C-MAC3, C-MAC4, and C-MAC4/SBT groups; however, worst glottic view (C/L 4) was only seen with DL, but not with C-MAC videolaryngoscopy. In the subgroup of patients that had suboptimal glottic view with DL (C/L≥2a; n = 24), glottic view was improved in the C-MAC4/SBT group; C/L class improved by three classes in 5 patients, by two classes in 2 patients, by one class in 8 patients, remained unchanged in 8 patients, or decreased by two classes in 1 patient. The median (range) time taken for tracheal intubation in the DL, C-MAC3, C-MAC4 and C-MAC4/SBT groups was 8 sec (2-91 sec; n = 44), 10 sec (2-60 sec; n = 37), 8 sec (5-80 sec; n = 18) and 12 sec (2-70 sec; n = 51), respectively.ConclusionsCombining the benefits of conventional direct laryngoscopy and videolaryngoscopy in one device, the C-MAC may serve as a standard intubation device for both routine airway management and educational purposes. However, in patients with suboptimal glottic view (C/L≥2a), the C-MAC size 4 with straight blade technique may reduce the number of C/L 3 or C/L 4 views, and therefore facilitate intubation. Further studies on patients with difficult airway should be performed to confirm these findings.

First Clinical Evaluation of the C-MAC D-Blade Videolaryngoscope During Routine and Difficult Intubation

In the present preliminary study we evaluated the C-MAC® D-Blade (Karl Storz, Tuttlingen, Germany), a new videolaryngoscopic C-MAC blade for difficult intubation, during both routine and difficult intubations. First, both the conventional direct laryngoscopy and the D-Blade were used in 15 consecutive patients with normal airways during routine induction of anesthesia. Second, the D-Blade was used as a rescue device in 20 of 300 (6.7%) consecutive patients, when conventional direct laryngoscopy failed. In the 15 patients during routine induction of anesthesia, with direct laryngoscopy, a Cormack-Lehane (C/L) grade 1 and grade 2a view was seen in 7 and 8 patients, respectively. It was possible to insert the D-Blade and to get a video view of the glottis on the first attempt in all patients; with the D-Blade, all 15 patients had a C/L 1 view. The time to successful intubation with the D-Blade was 15 (8-26) seconds (median (range)). In the 20 patients, in whom unexpected difficulty with direct laryngoscopy was observed, C/L grades 3 and 4 were present in 15 and 5 patients, respectively. With the use of the D-Blade, indirect C/L video view improved to C/L class 1 in 15 patients, and to 2a in 5 patients, respectively. The time from touching the laryngoscope to optimal laryngoscopic view was 11 (5-45) seconds and for successful intubation 17 (3-80) seconds. In all 35 patients, with the D-Blade no direct view of the glottis was possible and subsequently a semiflexible tube guide was required.

72: A Randomized, Crossover Comparison of C-Mac Dblade, Glidescope, and Conventional Macintosh Laryngoscopy During Routine Induction of Anesthesia

72: A Randomized, Crossover Comparison of C-Mac Dblade, Glidescope, and Conventional Macintosh Laryngoscopy During Routine Induction of Anesthesia

Comparison of modified and conventional methods in orotracheal intubetion of GlideScope videolaryngoscope

To compare the modified and conventional methods in orotracheal intubation of GlideScope videolaryngoscope. Sixty patients aged 21-53 years with ASA physical status I-II were scheduled for elective abdominal operation under general anesthesia. After routine anesthesia induction orotracheal intubation was performed with GlideScope videolaryngoscope; the patients were randomly divided into two groups (n=30 in each): Group M received modified orotracheal intubation and Group C received conventional orotracheal intubation. Noninvasive blood pressure and heart rate were recorded before and after anesthesia induction, at intubation, 1 and 3 min after intubation. The time of intubation procedure was significantly longer in Group C than in Group M. BP and HR significantly decreased after intubation, there were no differences between two groups. The modified method can improve the readiness of the procedure but it shows no advantages in prevention of adverse hemodynamic responses during the orotracheal intubetion of videolaryngoscopy.

The C-MAC Videolaryngoscope: First Experiences with a New Device for Videolaryngoscopy-Guided Intubation

We studied the efficacy of the C-MAC (Karl Storz, Tuttlingen, Germany), a new portable videolaryngoscope, in 60 patients during routine induction of anesthesia. It was possible to insert the blade (Size 3) of the C-MAC and to get a view of the glottis on the first attempt in all patients. Tracheal intubation also was successful in all 60 patients; 52 patients were intubated on the first attempt, 6 on the second, and 2 on the third. In 8 patients (13%), a gum elastic bougie guide was required. A Cormack-Lehane Class 1 view of the glottis was seen in 30 patients without external manipulation and in 45 with external manipulation, Class 2a view in 22 without and 12 with, Class 2b in 2 without, and Class 3 in 2 without manipulation. The median time taken for tracheal intubation was 16 s (range, 6-58 s). In addition, we describe our experience with 3 patients in whom we had unexpected difficulty with direct laryngoscopy with a conventional Macintosh laryngoscope (Cormack-Lehane Class 3, 4, and 4, respectively). These patients' airways were successfully managed on the first attempt when using the C-MAC Size 4 blade (improvement to Cormack-Lehane Class 1, 2a, and 2b, respectively) in a modified manner by uploading the epiglottis, which is known as "straight blade technique."

Optimising the unprotected airway with a prototype Jaw‐Thrust‐Device – a prospective randomised cross‐over study

Despite being a standard procedure during induction of anaesthesia, facemask ventilation can be a major challenge especially for inexperienced anaesthetists. We manufactured a Jaw-Thrust-Device designed to keep the patient's jaws in an optimised position, and thus to maintain the airway in a permanently patent state. Using a cross over design, we compared the influence of using the Esmarch manoeuvre (bimanual jaw-thrust), a nasopharyngeal airway, an oropharyngeal airway, or the Jaw-Thrust-Device on airway physiology in 50 healthy adults with body mass index < 35 kg.m(-2), undergoing standard facemask ventilation for routine induction of anaesthesia. The main study endpoints were expiratory tidal volumes, airway resistances, and gas flow rates. The Jaw-Thrust-Device was more effective in increasing expiratory tidal volumes and peak inspiratory flow than a standard Esmarch manoeuvre, and was more effective than both nasopharyngeal and oropharyngeal airways in decreasing airway resistance.

Cardiogenic shock following nasal septoplasty: a case report and review of the literature

Nasal septoplasty is a surgical procedure offered to patients with chronic snoring secondary to nasal obstruction. We describe a case of cardiogenic shock following the administration of metoprolol to treat hypertension, (likely) induced by systemic absorption of topical epinephrine used during a routine nasal septoplasty. A 29-yr-old male, with no significant medical history, was scheduled for nasal septoplasty for mild nasal obstruction. Following routine anesthetic induction, cotton balls, soaked with epinephrine (1:1000), were applied to the nasal mucosa. The patient became hypertensive with a blood pressure of 207/123 mmHg. Intravenous metoprolol was administered. Severe pulmonary edema ensued, with resulting hypoxic respiratory failure and cardiogenic shock. The patient was transferred to a tertiary care facility for percutaneous cardiopulmonary bypass. After five days of cardiopulmonary bypass support and six weeks of intensive care monitoring, the patient's cardiac status returned to normal limits. A hypertensive response, following systemically absorbed topical vasoconstrictors, including both phenylephrine and epinephrine, can be associated with dire consequences when treated with a beta-adrenergic blocking drug and, possibly, calcium channel blockers. To prevent severe complications including; pulmonary edema, cardiogenic shock, cardiac arrest, and, possibly, death, these drug interactions need to be appreciated.

Could ‘safe practice’ be compromising safe practice? Should anaesthetists have to demonstrate that face mask ventilation is possible before giving a neuromuscular blocker?

I read with great interest the thought-provoking editorial by Calder and Yentis [1]. I wholeheartedly agree with the authors’ considerable reservations about the rationale and safety of the practice of having to demonstrate effective face mask ventilation before administering muscle relaxants. This practice is by no means restricted to the UK and is not entrenched only in the minds of trainees but as much in those of many senior anaesthetists. When hypoxaemia develops in the presence of impossible face mask ventilation and at a level of anaesthesia which precludes the timely return of adequate spontaneous respiration, the ‘point of no return’ has been reached and immediate access to the patient’s airway literally becomes a question of life or death. If, at such a point, optimal intubating conditions are not present, we may be acutely confronted with one of the most threatening situations in anaesthetic practice, namely the ‘can’t ventilate, can’t intubate’ situation. I would argue that the still wide-spread practice of ‘no muscle relaxant before effective face mask ventilation’ may per se contribute to, and at times even provoke, this serious situation which would have to be regarded as entirely iatrogenic in origin. To avoid such a life-threatening situation, even the sternest proponents of the ‘no muscle relaxant before effective face mask ventilation’ rule would generally not hesitate to administer a muscle relaxant when failed mask ventilation reaches a point at which the patient becomes hypoxic. The logical consequence of insisting on demonstration of effective mask ventilation before injecting the muscle relaxant would be abandonment of rapid sequence induction (RSI) altogether. Instead, awake fibreoptic endotracheal intubation would have to be performed in all patients fulfilling the indications for RSI. But again during RSI even the sternest proponents of the ‘no muscle relaxant before effective face mask ventilation’ rule do not hesitate to administer a normal to high dose of a hypnotic drug immediately followed by the administration of a muscle relaxant knowingly precluding the testing for effective face mask ventilation and the possibility of return of adequate spontaneous respiration in case of airway problems. If ensuring effective mask ventilation before injection of the muscle relaxant were that essential for patient safety, why then compromising on such safety during RSI? Why should we proceed differently during routine induction of anaesthesia? The findings by Kheterpal et al. [2, 3] clearly support the view that the earliest possible administration of the muscle relaxant may well be the most effective and safest tactic in routine clinical practice [1, 4, 5]. During the futile attempts at ‘forcing’ air into the lungs of non-paralysed patients, one can’t help getting the impression that we are continually demonstrating that ventilating lungs in the absence of muscle relaxation is most often more difficult than doing so during muscle relaxation. The term ritual refers to a pattern of behaviour repeated in a fixed form and order as though prescribed by custom or authority, or as a series of actions habitually and invariably followed by someone. The term dogma refers to a fixed belief that people are expected to accept without any doubts, and to concepts as being ‘established’ only according to a particular point of view, and thus one of doubtful foundation. Would it be all that inappropriate to apply the terms ritual and dogma to the practice of, and to the insistence on performing the practice of, no administration of muscle relaxants before demonstrating effective face mask ventilation, respectively?

A reply

We welcome the opportunity to reply to the comments made by Drs Menzies and Frerk. They are concerned that in some of the patients we described, difficult intubation should have been anticipated and alternative (awake) techniques employed. The crux of the article, however, was that in these cases, consultants, middle grades and trainees had not anticipated insurmountable difficulty in intubating these patients' tracheas – and when they did encounter difficulty, the Aintree Catheter technique proved very useful in rescuing the situation. Whether or not they should have anticipated difficulty is another matter. The series was presented primarily as a discussion around the Difficult Airway Society guidelines for ‘unanticipated difficult intubation during routine induction of anaesthesia’– Plan B: secondary intubation plan [1]. The report centred on the utility of the Aintree Catheter in managing failed intubation attempts when they occurred, not on how to avoid them in the first place. We agree that some of the patients could have been better managed initially using awake intubation. Their second point is that some of the patients should have been woken up and intubation attempts abandoned. We can re-assure them that none of the patients suffered failed oxygenation or ventilation using the classic laryngeal mask airway and so, in accordance with the secondary intubation plan, intubation via the classic laryngeal mask airway was attempted. Case 1 involved failed rapid sequence induction, but in the context of emergency airway protection in a trauma victim, not to facilitate surgery, and so awakening the patient and postponement was not applicable. We agree with Menzies and Frerk that patients who are potentially difficult to intubate should have their airways secured awake but, equally, we feel sure they would agree that doctors continue to fail to anticipate difficult intubation. This does not detract from our demonstration that the Aintree Catheter is useful in dealing with this very difficult circumstance, however, it should arise.

“Play it again, Sam”—a new approach to simulation

During the two weeks that medical students spend in anesthesia, we have scheduled them for two one-hour sessions in our simulator lab. During the first session, they are taught to perform a routine anesthetic induction and then a rapid-sequence induction. During the second session, they are presented with a case of ventricular fibrillation (VF) during general anesthesia. This scenario is followed by a debriefing session during which the students are introduced to the basic concepts of crisis resource management (CRM). A similar scenario is then run to reinforce the learning experience. The students complete an evaluation at the end of the clerkship and rate the lectures and simulation on a scale of one (low) to five (high). These assessments were then collected for analysis and evaluation. Results The average score for the lectures was 4.3 (from a possible score of 5). The average score for the simulation was 4.8. Comparison of these results using a student’s t-test indicated a significant difference (p<0.013). This indicates that the medical students prefer this method of learning to formal lectures. Discussion Simulation typically involves a scenario and debriefing session aimed at correcting errors and providing insight into why those errors occurred. However, allowing the trainee the opportunity to repeat the scenario and “get it right” has both academic and psychological advantages for both the trainee and the instructor. The instructor is able to verify that the material is understood and can be applied. The trainee benefits from the satisfaction of being able to demonstrate that he now knows how to perform the task successfully, thus reinforcing the material just learned, while also gaining confidence to deal with a similar clinical situation in the future. Thus, repeating the scenario resulted in a positive learning experience that was reflected in the high scores received in the evaluations.

Intragastric pressure and its relevance to protective cricoid force.

Cricoid pressure is frequently used to protect the anaesthetised and paralysed patient from passive regurgitation. Although intragastric pressure (Pga) drives regurgitation, its relevance in the setting of protective cricoid force has been largely ignored. We sought to define the likely range of Pga encountered in the population at risk. We studied 100 consecutive patients presenting for surgery requiring mechanical ventilation. We measured respiratory swings in Pga during mechanical ventilation in the paralysed state following rapid sequence induction (n = 24) and routine induction of anaesthesia (n = 76). Pga (mmHg) in the whole group recorded at end-inspiration (Pga-In) and end-expiration (Pga-Ex) was [mean (SD)]: Pga-In 6.48 (2.60) mmHg and Pga-Ex 3.23 (2.24) mmHg. We found no correlation between Pga and body mass index (r2 = 0.018). These findings have implications for the level of cricoid force required to protect a patient during the induction of anaesthesia.