Inconsistent size nomenclature in extraglottic airway devices.

BACKGROUND: Extraglottic airway devices (EADs) are frequently used airway devices, yet often they seal poorly, resulting in a functionally unacceptable leak. Optimal size selection of the EAD is therefore critical to the safe and effective use of an EAD. This review is designed to delineate the sizing recommendations of EADs and indicate the differences in order to make the optimal choice for device effectiveness and patient safety. METHODS: We searched manufacturing' guidelines regarding size recommendations of EADs. Alternative size selection suggestions were obtained through an extensive literature search. RESULTS: Most manufacturers offer different types and a wide range of (up to 8 different) sizes of EADs. Size ranges offered by manufacturers are most often based on weight, although some manufacturers offer alternative EADs based on a variety of patient variables (age, gender, height). Even 'one-size-fits-all' adult EADs have been introduced into clinical practice. Special formulae and methods are suggested to aid the clinician to find the optimal EAD size, especially for children. CONCLUSION: Selecting the appropriate size of an EAD is critical to optimal use, although applying the correct size of an EAD has been subject of controversy, as recommendations on sizing differ substantially and are far from a coherent and universal sizing system. Successful use of an EAD depends in part on appropriate size selection, in addition to clinical judgment, as well as patient anatomy and physiology. Standardization in the use of EAD sizes and a consensus about a consistent size systematic of EADs would benefit to promote a safer clinical practice in airway management.

Tracheal intubation of patients in non-standard positions requires training.

In extreme emergency situations, patients may need to undergo endotracheal intubation, while in a non-supine position. This manuscript offers several options to the anesthesiologist to cope with tracheal intubations in non-standard positions. The authors stress that there is a need for adequate training in an anaesthesia skills lab, whereby classic direct laryngoscopy and indirect videolaryngoscopy should be practiced on manikins, before our trainees actually practice anesthesia on patients in operating theatres. This manuscript is also a plea for developing an algorithm for emergency airway management in the non-supine position.

The usage of the Boussignac continuous positive airway pressure system in acute respiratory failure.

Traditionally, continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BiPAP) devices have been used to treat patients in acute respiratory failure. However they require an electric power source, are relatively large in size, and may be difficult to use in prehospital settings. The recently introduced Boussignac CPAP system is capable of delivering 10 cmH2O of CPAP, is compact, portable and requires only an oxygen source. This paper reviews the efficacy of using Boussignac CPAP as a treatment for acute respiratory failure in both prehospital and hospital settings. All studies mainly focused on patients treated for cardiogenic pulmonary edema. In the prehospital setting, Boussigac CPAP significantly improved respiratory parameters and oxygenation from baseline values. In the emergency department setting, Boussignac CPAP was more effective than standard oxygen delivery and just as effective as BiPAP in improving patient oxygenation and respiration. In one study, implementing Boussignac CPAP reduced intubation rate and hospital stay. Most hospital staff found Boussignac CPAP easy to use and complication rates were low. Boussigac CPAP is a useful device in the treatment of patients with acute respiratory failure, especially in the prehospital setting.

The LMA-Supreme™ as an intubation conduit in patients with known difficult airways: a prospective evaluation study.

BACKGROUND: Many extraglottic airway devices allow the direct passage of an adult-sized tracheal tube, but this is not possible with the LMA-Supreme(TM) . We evaluated the feasibility of using the LMA-Supreme(TM) as a conduit for intubation in patients with known difficult airways. METHODS: Sixty-eight adult patients, with preoperative predictors of difficult intubation, were scheduled for elective surgery under general anaesthesia. After assessing the direct laryngoscopy view, 23 patients with Cormack-Lehane III/IV were included in the study. An LMA-Supreme(TM) was inserted, followed by the passage of a flexible bronchoscope loaded with an Aintree Intubation Catheter into the trachea. The bronchoscope and LMA-Supreme(TM) were removed, and a tracheal tube was railroaded over the Aintree Intubation Catheter into the trachea. RESULTS: Tracheal intubation was successful in all patients using the above technique. SpO(2) was >95% during the intubation procedure. CONCLUSIONS: We conclude that the LMA-Supreme(TM) is a successful conduit for bronchoscopic/Aintree Intubation Catheter-guided intubation in patients with known difficult airway.

Archie Brain: celebrating 30 years of development in laryngeal mask airways.

The practice of anaesthesia was revolutionised by the ideas of Archie Brain. The routine use of a facemask to manage the airway was not a hands-free technique, despite the development of various harnesses, and made adequate record-keeping difficult. The tracheal tube was associated with some morbidity, which some felt was unsuitable for day surgery. Brain developed an airway management device that was less stressful to the patient than tracheal intubation, and was, however, as safe as using a facemask and airway. Brain also hoped his device would function for cases where mask ventilation was particularly difficult and thus give anaesthetists a safer alternative to a complex intubation, especially in emergency scenarios.

Similar oropharyngeal leak pressures during anaesthesia with i-gel, LMA-ProSeal and LMA-Supreme Laryngeal Masks.

INTRODUCTION: We test the hypothesis that there are differences in performance among three extra-glottic airway devices during spontaneous breathing anaesthesia. METHODS: One hundred and fifty consecutive patients (ASA Grade 1-2, aged 18-80 yr) were randomly allocated for airway management with the i-gel (Intersurgical Ltd, Wokingham, Berkshire UK), the LMA-ProSeal and the LMA-Supreme (The Laryngeal Mask Company Ltd, Wooburn Green, Bucks, UK). Anaesthesia was with fentanyl/propofol/sevoflurane mixture. A laryngoscope-guided, gastric tube-guided technique was used for insertion. The following primary variables were assessed: ease of insertion, effective airway time, anatomical position, oropharyngeal leak pressure among devices, and change in oropharyngeal leak pressure between 30 and 60 minutes for each device during the spontaneous breathing anaesthesia. RESULTS: Differences detected were that the LMA-Supreme was easier to insert and had a shorter effective airway time than the LMA-Proseal and i-gel. Anatomical position was better for the LMA-Supreme than for the i-gel. Oropharyngeal leak pressures were similar among devices during apnoea and spontaneous ventilation, but much higher than in the first generation classic type of laryngeal masks. There were no changes in oropharyngeal leak pressure for any device during the spontaneous breathing phase. There were no differences in performance for any variable between the LMA-ProSeal and i-gel. CONCLUSION: The LMA-Supreme is easier and quicker to insert than the LMA-ProSeal and i-gel using a laryngoscope-guided, gastric tube-guided technique and is associated with better anatomical positioning than the i-gel. Oropharyngeal leak pressures are similar among devices.

Evaluation of the Mediseus epidural simulator.

The demand for increased patient safety has led to greater use of simulation training of health professionals performing medical procedures. The study aim was to evaluate the usefulness of the Mediseus® Epidural Simulator in teaching basic epidural needle-handling skills. Three groups of 15 anaesthetists (Novice=zero to two year anaesthesia trainees; Intermediate=three- to five-year anaesthesia trainees; Expert=consultants and regional-specialist anaesthetists) from three different medical centres participated. Each participant performed 20 simulated epidural needle insertions and was scored on several parameters (e.g. time, success of the insertion, bone collisions). Following familiarisation with the simulator and the needle insertions, participants answered seven questions on the applicability of the simulator to the teaching of basic epidural needle-handling skills. There was a clear learning effect with regard to the simulation procedure time, this decreasing throughout the experiment (P=0.037). There was no significant influence of either group or experience with the simulator in the study on the number or type of errors made. The quality of the simulation was scored 2.3 out of 5.0 (for bone simulation) and 4.7 (for loss-of-resistance simulation). All groups considered that the simulator was best suited for training prospective anaesthetists. Each group rated the usefulness of the simulator for training novices at greater than 3.0 out of 5.0. The Mediseus® Epidural Simulator seems to be an appropriate training device for an introduction to epidural needle insertion. For medical professionals with procedural knowledge, the simulation is not realistic enough and the simulator did not distinguish between the groups based on the errors made.

Effect of the mode of administration of inhaled anaesthetics on the interpretation of the F(A)/F(I) curve--a GasMan simulation.

The effects of blood solubility, cardiac output and ventilation on the rise of the alveolar towards the inspired concentration, the F(A)/F(I) curve, of an inhaled anaesthetic are often thought to reflect how these factors affect wash-in of the central nervous system compartment and, therefore, speed of induction because F(A) is the partial pressure ultimately attained in the central nervous system (F(VRG)). These classical F(A)/F(I) curves assumed a constant F(I). We used GasMan to examine whether changes in solubility, cardiac output and ventilation affect the relationship between the F(A)/F(I) curve and F(VRG) differently while either F(I) or F(A) are kept constant. Using GasMan, we studied the effects of solubility (desflurane vs isoflurane), cardiac output (5 vs. 10 l x min(-1)) and minute ventilation (4 vs. 8 l x min(-1)) on F(A), F(I), F(A)/F(I) and F(VRG) with either F(I) kept constant or F(A) kept constant (at 1 minimum alveolar concentration). High fresh gas flows were used to avoid rebreathing, so that the delivered concentration matched F(I). Despite similar effects on the F(A)/F(I) curve, the effects on F(VRG) differed. With constant F(I), lower solubility or higher ventilation results in a higher F(VRG) and a higher cardiac output results in a lower F(VRG). With constant F(A), solubility has only a minimal effect on F(VRG); an increase in cardiac output hastens the rise of F(VRG) to the same plateau value; and a change in ventilation has minimal effect on F(VRG). Despite similar effects on the F(A)/F(I) curve, the effects of solubility, cardiac output and ventilation on the F(VRG) are different when either F(I) or F(A) are kept constant. With the F(I) kept constant, induction of anaesthesia is slower with a higher cardiac output, but with F(A) kept constant, induction of anaesthesia is faster with a higher cardiac output. The introduction of an end-expired closed-loop feedback administration of inhaled anaesthetics makes this distinction clinically relevant.

Derivation and prospective testing of a two-step sevoflurane-O2-N2O low fresh gas flow sequence.

Simple vaporiser setting (F(D)) and fresh gas flow (FGF) sequences make the practice of low-flow anaesthesia not only possible but also easy to achieve. We sought to derive a sevoflurane F(D) sequence that maintains the end-expired sevoflurane concentration (F(A)sevo) at 1.3% using the fewest possible number of F(D) adjustments with a previously described O2-N2O FGF sequence that allows early FGF reduction to 0.7 l min(-1). In 18 ASA physical status I to IH patients, F(D) was determined to maintain F(A)sevo at 1.3% with 2 l min(-1) O2 and 4 l min(-1) N2O FGF for three minutes, and with 0.3 and 0.4 l min(-1) thereafter. Using the same FGF sequence, the F(D) schedule that approached the 1.3% F(A)sevo pattern with the fewest possible adjustments was prospectively tested in another 18 patients. The following F(D) sequence approximated the F(D) course well: 2% from zero to three minutes, 2.6% from three to 15 minutes and 2.0% after 15 minutes. When prospectively tested, median (25th; 75th percentile) performance error was 0.8 (-2.9; 5.9)%, absolute performance error 6.7 (3.3; 10.6)%, divergence 18.2 (-5.6; 27.4)%.h(-1) and wobble 4.4 (1.7; 8.1) %. In one patient, FGF had to be temporarily increased for four minutes. One O2/N2O rotameter FGF setting change from 6 to 0.7 l min(-1) at three minutes and two sevoflurane F(D) changes at three and 15 minutes maintained predictable anaesthetic gas concentrations during the first 45 minutes in all but one patient in our study.