Rescue oxygenation success by cannula or scalpel-bougie emergency front-of-neck access in an anaesthetised porcine model.

In the obese, the evidence for the choice of the optimal emergency front-of-neck access technique is very limited and conflicting. We compared cannula and scalpel-bougie emergency front-of-neck access techniques in an anaesthetised porcine model with thick pretracheal tissue. Cannula and scalpel-bougie cricothyroidotomy techniques were performed in 11 and 12 anaesthetised pigs, respectively. Following successful tracheal access, oxygenation was commenced and continued for 5 min using Rapid-O2 device for cannula and circle breathing system for scalpel-bougie study groups. The primary outcome was a successful rescue oxygenation determined by maintenance of arterial oxygen saturation >90% 5 min after the beginning of oxygenation. Secondary outcomes included success rate of airway device placement, time to successful airway device placement, and trauma to the neck and airway. The success rate of rescue oxygenation was 18% after cannula, and 83% after scalpel-bougie technique (P = 0.003). The success rate of airway device placement was 73% with cannula and 92% with scalpel-bougie technique (P = 0.317). Median (inter-quartile-range) times to successful airway device placement were 108 (30-256) and 90 (63-188) seconds (P = 0.762) for cannula and scalpel-bougie emergency front-of-neck access, respectively. Proportion of animals with iatrogenic trauma additional to the procedure itself was 27% for cannula and 75% for scalpel-bougie technique (P = 0.039). Thus, in the porcine model of obesity, the scalpel-bougie technique was more successful in establishing and maintaining rescue oxygenation than cannula-based technique; however, it was associated with a higher risk of severe trauma.

CHALLENGES IN THE USE OF VIDEO LARYNGOSCOPES.

Despite the lack of uniformity and the need of further investigation, video laryngoscopy continues to gain popularity both inside and outside the operating room. It has quickly become a first line strategy for potential and/or encountered difficult intubation. It is well established that video laryngoscope improves laryngeal view as compared with direct laryngoscopy in patients with suspected difficult intubation and simulated difficult airway scenarios. For novices and experienced anesthesiologists alike, video laryngoscopy is easy to use and the skills involved are easy to master. However, it is important to say that video laryngoscopes may be used in a variety of clinical scenarios and settings because of the video laryngoscope design offering an alternative intubation technique in both anaesthetized and awake patients. The aim of this article is to show and highlight clinical situations in which the use of video laryngoscope is a challenge for an experienced anesthesiologist in solving the airway. Challenges in the use of video laryngoscope with which we deal and encounter in everyday clinical practice that are discussed in this paper are intubation in the prehospital setting and emergency departments, intubation in Intensive Care Unit, intubation in a patient with cervical spine immobilization, and awake video laryngoscopy-assisted tracheal intubation in the obese. We also point out the important role of video laryngoscope as a tool for teaching and training in airway education. Training and education in difficult airway management is essential to improve patient safety at endotracheal intubation in emergency situation.

ALTERNATIVE DEVICES IN AIRWAY VISUALIZATION.

The Macintosh laryngoscope has been the most widely used device for intubation since its invention by Foregger in the 1940s. Recently, video and optic laryngoscopy assisted tracheal intubation has been used widely in patients with difficult airways. Their routine use, however, is not widely practiced. This review will summarize some of the newly available devices to assist tracheal intubation, with their advantages and disadvantages when compared with conventional laryngoscopes. It also presents the reasons to support their use in both elective and emergency airway management.

A survey of anaesthetic practice in predicting difficult intubation in UK and Europe.

CONTEXT: Unexpected difficulty in tracheal intubation is an intermittent and often terrifying problem for all practising anaesthetists. There are many preoperative assessment tests to predict a difficult laryngeal view or a difficult intubation, but we found no published evidence of how frequently these predictive tests are used or how useful they are perceived to be by anaesthetists. OBJECTIVE: We decided to ask UK and non-UK anaesthetists attending the Annual Scientific Meeting of the European Society of Anaesthesiology about their practice in predicting difficult intubation. DESIGN: The study was conceived as a survey. SETTING: The airway tests were compiled into a questionnaire, hand distributed among anaesthetists at Euroanaesthesia - the European group (after excluding UK attendees) - and posted to randomly selected anaesthetists in the UK - the UK group. PARTICIPANTS: Overall, 888 of 1230 (72%) questionnaires were completed. The response rate from the UK group of anaesthetists was 69% (481 of 700) and from the European group was 77% (407 of 530). RESULTS: On a scale 1 (never) to 5 (always), the mean score for frequency of use was similar for both groups of anaesthetists and ranged from about 4 for mouth opening to about 1 for Nodding Donkey. The mean score for usefulness (1 = useless, 5 = extremely useful) ranged from about 3.7 to 2 for the same two tests. The UK group found most tests slightly less useful than did the European group. With regard to the frequency of assessing the airway, 9% of the European group, but 16% of the UK group, failed always (score 5) or regularly (score 4) to assess the airway before general anaesthesia. Furthermore, 21 and 36% of the UK and European groups, respectively, failed to do so before regional anaesthesia. CONCLUSION: These results are a cause for concern with regard to both airway management training and patient safety.

Airway management disasters--lessons from the United Kingdom.

The Fourth National Audit Project (NAP4) was set up by the Royal College of Anaesthetists and Difficult Airway Society to provide an insight into major complications of airway management in the United Kingdom. The NAP4 found that one serious airway complication such as death, brain damage, the need for surgical airway or unexpected intensive care admission, was reported for every 5500 general anaesthetics. Most of the events happened during daytime to a senior experienced clinicians. Airway assessment was not recorded before surgery in 74% of patients that ended up with life threatening airway complications. Aspiration was responsible for 26% of life threatening airway complications and for 50% of all deaths. The NAP4 found that airway problems were twice as common in obese patients (BMI 30-35) and four times as common in morbidly obese (BMI >35). Awake fibreoptic intubation was indicated and not performed in a significant number of reported incidents. Thirty percent of serious airway complications were associated with extubation or removal of laryngeal mask airway at the end of anaesthesia. The findings of the NAP4 have the potential to significantly influence airway management practice of all anaesthetists irrespective of where in the world they practice anaesthesia.

Extubation after anaesthesia: a randomised comparison of three techniques.

The mode of ventilation used during awake extubation has not previously been studied. We conducted a randomised controlled trial comparing spontaneous respiration, intermittent positive pressure ventilation, and pressure support ventilation (each n = 13) for incidence and severity of peri-extubation complications following routine elective surgery. We found the severity of peri-extubation cough was significantly affected by mode of ventilation used at extubation (p = 0.049), with lowest severity grades for those in the pressure support ventilation group. The mean arterial pressure at extubation was lowest in the intermittent positive pressure ventilation group (p = 0.007). Other peri-extubation complications and time to extubation following cessation of anaesthesia were not significantly different across the three groups. We suggest that the use of pressure support ventilation for awake extubation may offer an advantage over spontaneous and intermittent positive pressure ventilation extubation strategies.

Evaluation of a pulse oximeter sensor tester.

OBJECTIVE: The Lightman is intended to test the optical and electrical properties of a pulse oximeter probe including the wavelength of the light emitting diode by means of a micro spectrometer. The aim of this study was to evaluate the ability of the Lightman to detect faulty pulse oximeter finger probes by testing the accuracy of the wavelength of the light emitting diode in isolation from the monitor. METHODS: The pulse oximeter measurements of arterial oxygen saturation from the "accurate" and "inaccurate" probes, as identified by the Lightman, were compared with arterial saturation determined by a co-oximeter. Data was analysed from 63 sets of measurements. In addition, we conducted a national survey to determine the testing procedures used by the Biomedical Engineering departments to evaluate the accuracy of pulse oximeter devices. RESULTS: The bias [95% limits of agreement] for accurate, over-reading and under-reading probes were 0.17% [3.6 to -3.3], 1.44% [5.4 to -2.5] and -1.6% [2.6 to -5.8] respectively. The response rate to the national survey was 75% (142/189); a pulse oximeter tester was used by 93/142 (65%) trusts. CONCLUSIONS: Our findings suggest that the Lightman can detect faulty probes and predict reasonably accurately the direction of the probe's error. The Lightman may be considered as a useful tool to assess the accuracy of pulse oximeters. The national survey highlighted a wide variation in the testing procedure utilised to evaluate the accuracy of pulse oximeters. Introduction of guidelines regarding the testing procedure would promote a uniform practice.