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We catalog the 443 bright supernovae discovered by the All-Sky Automated Survey for Supernovae (ASAS-SN) in $2018-2020$ along with the 519 supernovae recovered by ASAS-SN and 516 additional $m_{peak}\leq18$ mag supernovae missed by ASAS-SN. Our statistical analysis focuses primarily on the 984 supernovae discovered or recovered in ASAS-SN $g$-band observations. The complete sample of 2427 ASAS-SN supernovae includes earlier $V$-band samples and unrecovered supernovae. For each supernova, we identify the host galaxy, its UV to mid-IR photometry, and the offset of the supernova from the center of the host. Updated light curves, redshifts, classifications, and host galaxy identifications supersede earlier results. With the increase of the limiting magnitude to $g\leq18$ mag, the ASAS-SN sample is roughly complete up to $m_{peak}=16.7$ mag and is $90\%$ complete for $m_{peak}\leq17.0$ mag. This is an increase from the $V$-band sample where it was roughly complete up to $m_{peak}=16.2$ mag and $70\%$ complete for $m_{peak}\leq17.0$ mag., Comment: 14 pages, 7 figures, 4 tables. Updated to reflect changes made in the published version. Tables containing the catalog data presented in this submission are included in machine-readable format as ancillary files

We analyze the 476 SN Ia host galaxies from the All-Sky Automated Survey for Supernova (ASAS-SN) Bright Supernova Catalogs to determine the observed relative Type Ia supernova (SN) rates as a function of luminosity and host galaxy properties. We find that the luminosity distribution of the SNe Ia in our sample is reasonably well described by a Schechter function with a faint-end slope $\alpha \approx 1.5$ and a knee $M_{\star} \approx -18.0$. Our specific SN Ia rates are consistent with previous results but extend to far lower host galaxy masses. We find an overall rate that scales as $(M_{\star}/10^{10} M_{\odot})^{\alpha}$ with $\alpha \approx -0.5$. This shows that the specific SN Ia rate continues rising towards lower masses even in galaxies as small as $\log(M_{\star} / M_{\odot}) \lesssim 7.0$, where it is enhanced by a factor of $\sim10-20$ relative to host galaxies with stellar masses $\sim10^{10}M_{\odot}$. We find no strong dependence of the specific SN Ia rate on the star formation activity of the host galaxies, but additional observations are required to improve the constraints on the star formation rates., Comment: 15 pages, 10 figures, 2 tables available online

In this catalog we compile information for all supernovae discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN) as well as all other bright ($m_{peak}\leq17$), spectroscopically confirmed supernovae found in 2017, totaling 308 supernovae. We also present UV through near-IR magnitudes gathered from public databases of all host galaxies for the supernovae in the sample. We perform statistical analyses of our full bright supernova sample, which now contains 949 supernovae discovered since 2014 May 1, including supernovae from our previous catalogs. This is the fourth of a series of yearly papers on bright supernovae and their hosts from the ASAS-SN team, and this work presents updated data and measurements, including light curves, redshifts, classifications, and host galaxy identifications, that supersede information contained in any previous publications., 14 pages, 6 figures, 4 tables. Updated to reflect changes made in the published version. Tables containing the catalog data presented in this submission are included in machine-readable format as ancillary files

We present the discovery that ASASSN-14ko is a periodically flaring AGN at the center of the galaxy ESO 253-G003. At the time of its discovery by the All-Sky Automated Survey for Supernovae (ASAS-SN), it was classified as a supernova close to the nucleus. The subsequent six years of V- and g-band ASAS-SN observations reveal that ASASSN-14ko has nuclear flares occurring at regular intervals. The seventeen observed outbursts show evidence of a decreasing period over time, with a mean period of $P_0 = 114.2 \pm 0.4$ days and a period derivative of $\dot{P} = -0.0017\pm0.0003$. The most recent outburst in May 2020, which took place as predicted, exhibited spectroscopic changes during the rise and a had a UV bright, blackbody spectral energy distribution similar to tidal disruption events (TDEs). The X-ray flux decreased by a factor of 4 at the beginning of the outburst and then returned to its quiescent flux after ~8 days. TESS observed an outburst during Sectors 4-6, revealing a rise time of $5.60 \pm 0.05$ days in the optical and a decline that is best fit with an exponential model. We discuss several possible scenarios to explain ASASSN-14ko's periodic outbursts, but currently favor a repeated partial TDE. The next outbursts should peak in the optical on UT 2020-09-7.4$ \pm $1.1 and UT 2020-12-26.5$ \pm $1.4., Comment: 26 pages, 15 figures, 7 tables. Will be submitted to ApJ. The latest flare is currently ongoing, as we predicted

We present photometric and spectroscopic observations of the unusual Type Ia supernova ASASSN-18tb, including a series of SALT spectra obtained over the course of nearly six months and the first observations of a supernova by the Transiting Exoplanet Survey Satellite (TESS). We confirm a previous observation by Kollmeier et al. (2019) showing that ASASSN-18tb is the first relatively normal Type Ia supernova to exhibit clear broad ($\sim1000$ km s$^{-1}$) H$\alpha$ emission in its nebular phase spectra. We find that this event is best explained as a sub-Chandrasekhar mass explosion with $M_{Ni} \approx 0.3\; \rm{M}_\odot$. Despite the strong H$\alpha$ signature at late times, we find that the early rise of the supernova shows no evidence for deviations from a single-component power-law and is best fit with a moderately shallow power-law of index $1.69\pm0.04$. We find that the H$\alpha$ luminosity remains approximately constant after its initial detection at phase +37 d, and that the H$\alpha$ velocity evolution does not trace that of the Fe~III$~\lambda4660$ emission. These suggest that the H$\alpha$ emission arises from circumstellar medium (CSM) rather than swept up material from a non-degenerate companion. However, ASASSN-18tb is strikingly different from other known CSM-interacting Type Ia supernovae in a number of significant ways. Those objects typically show an H$\alpha$ luminosity two orders of magnitude higher than what is seen in ASASSN-18tb, pushing them away from the empirical light-curve relations that define "normal" Type Ia supernovae. Conversely, ASASSN-18tb exhibits a fairly typical light curve and luminosity for an underluminous or transitional SN Ia, with $M_R \approx -18.1$ mag. Moreover, ASASSN-18tb is the only SN Ia showing H$\alpha$ from CSM interaction to be discovered in an early-type galaxy., Comment: 13 pages, 8 figures

We present ground-based and Swift photometric and spectroscopic observations of the candidate tidal disruption event (TDE) ASASSN-14li, found at the center of PGC 043234 ($d\simeq90$ Mpc) by the All-Sky Automated Survey for SuperNovae (ASAS-SN). The source had a peak bolometric luminosity of $L\simeq10^{44}$ ergs s$^{-1}$ and a total integrated energy of $E\simeq7\times10^{50}$ ergs radiated over the $\sim6$ months of observations presented. The UV/optical emission of the source is well-fit by a blackbody with roughly constant temperature of $T\sim35,000$ K, while the luminosity declines by roughly a factor of 16 over this time. The optical/UV luminosity decline is broadly consistent with an exponential decline, $L\propto e^{-t/t_0}$, with $t_0\simeq60$ days. ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the optical and UV emission but declining at a slower rate, and the X-ray emission now dominates. Spectra of the source show broad Balmer and helium lines in emission as well as strong blue continuum emission at all epochs. We use the discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by ASAS-SN, finding an average rate of $r \simeq 4.1 \times 10^{-5}~{\rm yr}^{-1}$ per galaxy with a 90% confidence interval of $(2.2 - 17.0) \times 10^{-5}~{\rm yr}^{-1}$ per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia supernovae in 2014, a rate that is much higher than that of other surveys., 21 pages, 9 figures, 6 tables. Photometric data presented in this submission are included as ancillary files. Manuscript updated to reflect changes made in the published version. For a brief video explaining this paper, see https://youtu.be/CTbr-d7cWZc

We present comprehensive observations and analysis of the energetic H-stripped SN 2016coi (a.k.a. ASASSN-16fp), spanning the $\gamma$-ray through optical and radio wavelengths, acquired within the first hours to $\sim$420 days post explosion. Our campaign confirms the identification of He in the SN ejecta, which we interpret to be caused by a larger mixing of Ni into the outer ejecta layers. From the modeling of the broad bolometric light curve we derive a large ejecta mass to kinetic energy ratio ($M_{\rm{ej}}\sim 4-7\,\rm{M_{\odot}}$, $E_{\rm{k}}\sim 7-8\times 10^{51}\,\rm{erg}$). The small [\ion{Ca}{ii}] \lam\lam7291,7324 to [\ion{O}{i}] \lam\lam6300,6364 ratio ($\sim$0.2) observed in our late-time optical spectra is suggestive of a large progenitor core mass at the time of collapse. We find that SN 2016coi is a luminous source of X-rays ($L_{X}>10^{39}\,\rm{erg\,s^{-1}}$ in the first $\sim100$ days post explosion) and radio emission ($L_{8.5\,GHz}\sim7\times 10^{27}\,\rm{erg\,s^{-1}Hz^{-1}}$ at peak). These values are in line with those of relativistic SNe (2009bb, 2012ap). However, for SN 2016coi we infer substantial pre-explosion progenitor mass-loss with rate $\dot M \sim (1-2)\times 10^{-4}\,\rm{M_{\odot}yr^{-1}}$ and a sub-relativistic shock velocity $v_{sh}\sim0.15c$, in stark contrast with relativistic SNe and similar to normal SNe. Finally, we find no evidence for a SN-associated shock breakout $\gamma$-ray pulse with energy $E_{\gamma}>2\times 10^{46}\,\rm{erg}$. While we cannot exclude the presence of a companion in a binary system, taken together, our findings are consistent with a massive single star progenitor that experienced large mass loss in the years leading up to core-collapse, but was unable to achieve complete stripping of its outer layers before explosion., Comment: Submitted to ApJ. Main text: 21 pages; Appendix: 15 pages; 12 figures

We present extensive datasets for a class of intermediate-luminosity optical transients known as "luminous red novae" (LRNe). They show double-peaked light curves, with an initial rapid luminosity rise to a blue peak (at -13 to -15 mag), which is followed by a longer-duration red peak that sometimes is attenuated, resembling a plateau. The progenitors of three of them (NGC4490-2011OT1, M101-2015OT1, and SNhunt248), likely relatively massive blue to yellow stars, were also observed in a pre-eruptive stage when their luminosity was slowly increasing. Early spectra obtained during the first peak show a blue continuum with superposed prominent narrow Balmer lines, with P Cygni profiles. Lines of Fe II are also clearly observed, mostly in emission. During the second peak, the spectral continuum becomes much redder, Halpha is barely detected, and a forest of narrow metal lines is observed in absorption. Very late-time spectra (~6 months after blue peak) show an extremely red spectral continuum, peaking in the infrared (IR) domain. Halpha is detected in pure emission at such late phases, along with broad absorption bands due to molecular overtones (such as TiO, VO). We discuss a few alternative scenarios for LRNe. Although major instabilities of single massive stars cannot be definitely ruled out, we favour a common envelope ejection in a close binary system, with possibly a final coalescence of the two stars. The similarity between LRNe and the outburst observed a few months before the explosion of the Type IIn SN 2011ht is also discussed., Comment: 31 pages; 19 figures, 3 tables (plus 6 online tables). A&A, in press

As there are currently no data available comparing the practicability of the laryngeal mask airway (LMA) Supreme™ size 2 versus the laryngeal tube LTS II™ size 2 in children, this trial was conducted to quantify the differences between these two airway devices concerning leak pressure and fiber optic-controlled positioning in non-paralyzed, anesthetized pediatric patients. A total of 56 children aged 1–6 years and weighing between 11 and 23 kg were enrolled in the study. Anesthesia was intravenously induced according to local standards using fentanyl and propofol. After induction of anesthesia both airway devices were inserted consecutively in accordance with the randomization protocol. The mean oropharyngeal leak pressure was significantly higher for the LTS II™ (33±8 cmH2O) than for the LMA Supreme™ (21±7 cmH2O, p < 0.0001). Fiber optic position monitoring was better when the LMA Supreme™ was used (p < 0.001). The first attempt success rates for insertion (55Supreme LMA vs. 43LTSII, p < 0.001), the insertion time (25 s Supreme LMA vs. 34 s LTSII, p < 0.04) and the frequency of bloodstaining (0Supreme LMA vs 4LTSII, p < 0.04) for the initially used device were better for the LMA Supreme™ than the laryngeal tube LTS II™. We conclude that oropharyngeal leak pressure, fiber optic position, first attempt insertion success rate and bloodstaining differed between the LMA Supreme™ and the LTS II™ in children.

We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of Mu ,AB = -23.5 ± 0.1 and bolometric luminosity Lbol = (2.2 ± 0.2) × 10(45) ergs s(-1), which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ -25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 10(52) ergs, challenging the magnetar model for its engine.

We present an extensive set of photometric and spectroscopic data for SN 2009jf, a nearby Type Ib supernova, spanning from ~20 days before B-band maximum to one year after maximum. We show that SN 2009jf is a slow evolving and energetic stripped-envelope SN and is likely from a massive progenitor (25-30 solar masses). The large progenitor's mass allows us to explain the complete hydrogen plus helium stripping without invoking the presence of a binary companion. The supernova occurred close to a young cluster, in a crowded environment with ongoing star-formation. The specroscopic similarity with the He-poor Type Ic SN 2007gr suggests a common progenitor for some supernovae Ib and Ic. The nebular spectra of SN 2009jf are consistent with an asymmetric explosion, with an off-center dense core. We also find evidence that He-rich Ib supernovae have a rise time longer than other stripped-envelope supernovae, however confirmation of this result and further observations are needed.

We discuss ASASSN-13db, an EX Lupi-type ("EXor") accretion event on the young stellar object (YSO) SDSS J051011.01$-$032826.2 (hereafter SDSSJ0510) discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). Using archival photometric data of SDSSJ0510 we construct a pre-outburst spectral energy distribution (SED) and find that it is consistent with a low-mass class II YSO near the Orion star forming region ($d \sim 420$ pc). We present follow-up photometric and spectroscopic observations of the source after the $\Delta V \sim-$5.4 magnitude outburst that began in September 2013 and ended in early 2014. These data indicate an increase in temperature and luminosity consistent with an accretion rate of $\sim10^{-7}$ $\rm{M}_\odot$ yr$^{-1}$, three or more orders of magnitude greater than in quiescence. Spectroscopic observations show a forest of narrow emission lines dominated by neutral metallic lines from Fe I and some low-ionization lines. The properties of ASASSN-13db are similar to those of the EXor prototype EX Lupi during its strongest observed outburst in late 2008., Comment: 14 pages, 4 figures, 1 table. Updated May 2014 to reflect changes in the final version published in ApJL. Photometric data presented in this submission are included as ancillary files. For a brief video explaining this paper, see http://youtu.be/yRCCrNJnvtY

Over the last 10 years, the Laryngeal Mask Airway (LMA) has gained widespread acceptance as a general purpose airway for routine anaesthesia. Published data from large studies and reports have confirmed the safety and efficacy of the device for spontaneous and controlled ventilation during routine use. The initial experience with the LMA should ideally be confined to short cases requiring the patient to remain spontaneously ventilating. With experience, it will be found that less anesthetic agent is required during anesthesia with the LMA and patient recovery should be improved as a result. Spontaneous breathing is the chosen mode of ventilation in approximately 60% of LMA uses in the UK. During spontaneous breathing a minimal inspiratory pressure support will help with higher endtidal carbon dioxide levels. The anaesthetist should be experienced with using the LMA in spontaneously ventilating patients before using it with positive pressure ventilation. Several large scale studies have failed to show any link between positive pressure ventilation and pulmonary aspiration or gastric insufflation. The main disadvantage of the LMA is that it does not protect against aspiration. From a practical point of view, most fasted patients with normal lung compliance may be mechanically ventilated through the LMA to airway pressures of approximately 20 cmH2O. The low pressure seal implies that tidal volumes should be approximately 6-8 ml*kg-1 and the inspiratory flow rates should be reduced to achieve adequate and safe ventilation.

We conducted a randomized, cross-over study of 20 paralyzed anesthetized adult patients to test the hypothesis that oropharyngeal leak pressure and cuff position (assessed fiberoptically) vary with head and neck position for the flexible (FLMA) and standard laryngeal mask airway (LMA). Both devices were inserted into each patient in random order. Oropharyngeal leak pressure and fiberoptic position (including degree of rotation) were documented in four head and neck positions (neutral first, then flexion, then extension and rotation in random order) for each device. The size 5 was used for all patients, and the intracuff pressure was set at 60 cm HO in the neutral position. All airway devices were inserted at the first attempt. Oropharyngeal leak pressure was similar for the FLMA and LMA in the neutral (22 vs 21 cm HO), flexed (26 vs cm HO), and extended positions (19 vs 18 cm HO) but was slightly higher for the LMA when the head was rotated (19 vs 22 cm HO; P = 0.04). Compared with the neutral position, oropharyngeal leak pressure for the LMA was higher than flexion (26 vs 21 cm HO; P = 0.0004) and lower with extension (18 vs 21 cm HO; P = 0.03) but similar with rotation. Compared with the neutral position, oropharyngeal leak pressure for the FLMA was higher with flexion (26 vs 22 cm HO; P = 0.0001) and lower with extension (19 vs 22 cm HO; P = 0.03) and rotation (19 vs 22 cm HO; P = 0.03). The difference in oropharyngeal leak pressure between flexion and extension was 7 and 8 cm HO for the FLMA and LMA, respectively. Fiberoptic position was similar between devices and was unchanged by head and neck position. Rotation was not detected fiberoptically. We conclude that there are small changes in oropharyngeal leak pressure but no changes in cuff position in different head and neck positions for the FLMA and LMA. Oropharyngeal leak pressure may be improved by head and neck flexion and by avoiding extension. Implications: There are small changes in oropharyngeal leak pressure but no changes in cuff position in different head and neck positions for the flexible and standard laryngeal mask airways. Oropharyngeal leak pressure may be improved by head and neck flexion and by avoiding extension.

The cuffed oropharyngeal airway is a modified Guedel airway with a distal inflatable cuff and a proximal connector for attachment to an anaesthesia circuit. The purpose of this study was to evaluate this device for spontaneous ventilation anaesthesia in 100 adult patients. Anaesthesia was induced with fentanyl and propofol and maintained with nitrous oxide and isoflurane in oxygen. The device was inserted when anaesthetic depth was judged to be adequate. Adverse airway events and interventions (i.e. manoeuvres performed in order to provide a clear airway) were analysed from video recordings and detailed notes. The position of the device was assessed fibreoptically during spontaneous ventilation. The device provided a clear airway in 98% of patients during manually assisted ventilation, in 100% during spontaneous ventilation and in 100% during emergence. However, 91% of patients required at least one airway intervention at some time. Jaw lift was required for 33% of the time during manually assisted ventilation and 21% of the time during spontaneous ventilation. Most interventions occurred during the first 3 min of either manually assisted or spontaneous ventilation. The incidence of adverse airway events during manually assisted ventilation was 8%, during spontaneous ventilation was 5% and during emergence was 5%. Oxygen saturation briefly fell to between 87 and 89% on six occasions. On fibreoptic assessment, the vocal cords were visible in 29% of patients on fibreoptic assessment and the epiglottis was visible in 90%. Mild sore throat occurred in 4% of patients. We conclude that the cuffed oropharyngeal airway is suitable for spontaneous ventilation anaesthesia and has a low complication rate but that most patients require one or more interventions to provide a clear airway.

The safety of anaesthesia for gynaecological laparoscopy probably depends largely on short operative time, close intraoperative monitoring and the experience of both anaesthetist and surgeon. However, there is debate over the most suitable mode of ventilation and form of airway management. It is argued that hypoventilation and the risk of regurgitation make intubation and ventilation mandatory, and yet spontaneous ventilation with a facemask appears to be a safe technique with reduced minor morbidity. The laryngeal mask airway (LMA) has added a new dimension to the debate since it offers potential advantages over both the tracheal tube and the facemask. The aim of this review is to analyse the physiological and clinical evidence supporting the mode of ventilation and airway management during gynaecological laparoscopy and to discuss these issues in the context of the LMA. We conclude that the physiological and clinical data available to determine the suitability of the LMA is inadequate. Further proof is required before widespread adoption of these techniques. It is possible that advances in LMA design may extend the suitability of the LMA for gynaecological laparoscopy.

The ideal airway requirements for oral surgery are the provision of a stable, unobstructed airway, protection of the lungs from aspiration, minimal interference with the surgical field and a low complication rate. Neither the nasal mask nor endotracheal tube meet these requirements. The laryngeal mask airway (LMA), provides a third type of airway for consideration in oral surgery that offers some of the benefits of intubation and avoids many of the associated hazards. It can be inserted without use of a laryngoscope or muscle relaxants, and is designed to produce an airtight seal around the laryngeal inlet. It provides a secure airway suitable for spontaneous or controlled ventilation and acts as an airtight throat pack. Scavenging of waste gases is possible, and it is well tolerated during recovery. A modification, specifically designed for head, neck and dental anaesthesia, has recently become available. The purpose of this article is to provide a brief overview of the LMA with special emphasis on its use in oral surgery.

The laryngeal mask airway is a new general purpose airway that has revolutionized anaesthetic practice and has a potential role in emergency airway management, including neonatal resuscitation. It fills a niche between the face mask and tracheal tube and sits in the hypopharynx where it forms a circumferential low pressure seal around the glottis. All doctors involved in emergency airway management should have an understanding of the device and acquire skills in its use.

The Laryngeal Mask Airway (LMA) ProSeal(TM) and the i-Gel(TM) are two extraglottic devices with either an inflatable cuff or a non-inflatable cuff.We test the hypothesis that oropharyngeal leak pressure and fiberoptic position of the airway tube differ between the size 2 LMA ProSeal(TM) and the i-Gel(TM) in non-paralysed ventilated children.Fifty-one children aged 1.5-6 years weighing 10-25 kg were studied using a crossover design. Anaesthesia was with remifentanil/propofol mixture. The LMA ProSeal(TM) and the i-Gel(TM) were inserted into each patient in random order.Oropharyngeal leak pressure for the LMA ProSeal(TM) and the i-Gel(TM) was similar at 22 (5) and 21 (5) cm H(2) O, respectively. Fiberoptic position of the airway tube for the LMA ProSeal(TM) and the i-Gel(TM) was similar, with the vocal cords visible from the distal airway tube in 94% and 96%, respectively.We conclude that oropharyngeal leak pressure and fiberoptic position of the airway tube are similar for the size 2 LMA ProSeal(TM) and i-Gel(TM) in non-paralysed ventilated children.

The i-gel™ and LMA Supreme™ are extraglottic airway devices with non-inflatable and inflatable cuffs, respectively. We hypothesised that directly measured mucosal pressures would differ between these devices in anesthetised paralysed patients. Thirty patients were randomly allocated to receive one of these two devices. Four pressure sensors were attached to all airway devices used to measure mucosal pressure at the base of the tongue, the distal oropharynx, the hypopharynx and the pyriform fossa. At these four places, median (IQR [range]) i-gel mucosal pressures were 8.0 (2.7-10.7 [0-26.7]), 5.0 (2.7-7 [1.0-37.3]), 9.3 (2.7-13.3 [0-22.7] and 8.0 (2.7-10.7 [0-25.3]) cmH(2)O, respectively, and for the LMA Supreme, these were 5.0 (0.5-8.0 [0-33]), 4.0 (1.3-9.3 [0-24]), 10.7 (4-17.3 [0-26.7]) and 8.0 (0-10.7 [0-36]) cmH(2)O, respectively. Mucosal pressures were low and similar for both devices. The LMA Supreme mucosal pressures were higher in the hypopharynx than in the distal oropharynx (p = 0.04) and base of the tongue (p = 0.011). There were no pressure differences between the locations for the i-gel.

The laryngeal mask airway (LMA), first described by Brain in 1983, has an established role in the management of the airway during routine surgery. ‘GS! It can also help solve the problem of the patient who presents with a risk of difficult intubation since it can be used either as a definitive airway or as an aid to intubation.7.9 One of the outstanding features of the LMA is that it provides a rapid, clear airway in the vast majority of patients. Even inexperienced personnel have success rates of approximately 95% after minimal training”ql’ and in expert hands it can be successfully inserted in 98% of patients within 20 seconds using the standard technique.‘* The incidence of failed intubation in the obstetric population is approximately 1: 500,13 compared to the 1 in 2000 incidence of difficult intubation in the general surgical population.14 The immediately life threatening ‘can’t intubate, can’t ventilate’ situation is rare at 1 in 10000 anaesthetics in the general population.15 However, there is probably less than a 50’!% chance of predicting difficult intubation.16 Difficult or failed intubation was implicated in 6 out of 8 anaesthesia related deaths in the 1985-87 Report on Confidential Enquiries into Maternal Deaths in England and Wales (RCE).” Vanner noted that the overall modern obstetric mortality rate is only marginally less than the mortality from aspiration pneumonitis when ether and a facemask were commonly used. ’ * Rosen suggests that intubation should be limited to two attempts of 1 minute each, separated by 30 seconds of ventilation.lg Hasty surgical intervention during failed intubation (either tracheostomy or

Summary Ruptured abdominal aortic aneurysm currently accounts for about 1 in 200 deaths and is a critical surgical emergency with an average hospital mortality of 50%. The combination of acute massive haemorrhage in an elderly patient with pre-existing medical disease is highly lethal and a major challenge for any health care system. This article outlines the general principles of management and discusses the problems of haemodynamic assessment and preclamping fluid resuscitation.

Background We studied the reliability of epigastric auscultation to detect gastric insufflation in 30 anaesthetized, paralysed intubated patients. Methods A 16FG gastric tube was positioned with the tip in the mid-oesophagus with the proximal end attached to an injection port with a one-way valve. Four observers participated in the study. Observers were paired and each pair studied 15 patients. Each patient underwent four test sequences in random order, two by each observer. Each test sequence comprised one observer injecting different volumes of air (0.25 ml, 0.5 ml, 1 ml, 2 ml, 3 ml, 4 ml, 5 ml, 10 ml, 15 ml and 0 ml as a control) in random order whilst the second blinded observer listened with a stethoscope over the epigastrium. Each randomized volume was injected rapidly at 5 s intervals for 1 min. The number of injections required to detect air entering the stomach was recorded. The stomach was deflated between each test sequence. Results To detect air entering the stomach with 95% confidence, 11 injections were required for 0.25 ml; 7 for 0.5 ml; 3 for 1 ml; 2 for 2 ml and 3 ml, and 1 for ≥4 ml. The mean (range) inter- and intraobserver reliability was 0.73 (0.71–0.75) and 0.76 (0.76–0.89), respectively. The incidence of false positives was 21% (25/120) and the incidence of false negatives was 10% (103/1080), making the specificity and sensitivity 79% and 91%, respectively. Conclusions We conclude that epigastric auscultation can detect gastric insufflation of 0.25 ml air after 11 breaths and ≥4 ml air after one breath with 95% confidence. Inter- and intraobserver reliability is moderate to excellent. Epigastric auscultation should be repeated to reduce the risk of false positives.

In a randomised, non-crossover study, we tested the hypothesis that the ease of insertion using a duodenal tube guided insertion technique and the oropharyngeal leak pressure differ between the LMA ProSeal and the i-gel in non-paralysed, anesthetised female subjects. One hundred and fifty-two females aged 19-70 years were studied. Insertion success rate, insertion time and oropharyngeal leak pressure were measured. First attempt and overall insertion success were similar (LMA ProSeal, 75/76 (99%) and 76/76 (100%); i-gel 73/75 (97%) and 75 (100%), respectively). Mean (SD) insertion times were similar (LMA ProSeal, 40 (16) s; i-gel 43 (21) s). Mean oropharyngeal leak pressure was 7 cmH(2) O higher with the LMA ProSeal (p0.0001). Insertion of the LMA ProSeal and i-gel is similarly easy using a duodenal tube guided technique, but the LMA ProSeal forms a more effective seal for ventilation.

The Kuiper belt is a collection of small bodies (Kuiper belt objects, KBOs) that lie beyond the orbit of Neptune and which are believed to have formed contemporaneously with the planets. Their small size and great distance make them difficult to study. KBO 55636 (2002 TX300) is a member of the water-ice-rich Haumea KBO collisional family. The Haumea family are among the most highly reflective objects in the Solar System. Dynamical calculations indicate that the collision that created KBO 55636 occurred at least 1 Gyr ago. Here we report observations of a multi-chord stellar occultation by KBO 55636, which occurred on 9 October 2009 ut. We find that it has a mean radius of 143 ± 5 km (assuming a circular solution). Allowing for possible elliptical shapes, we find a geometric albedo of 0.88 +0.15 -0.06 in the V photometric band, which establishes that KBO 55636 is smaller than previously thought and that, like its parent body, it is highly reflective. The dynamical age implies either that KBO 55636 has an active resurfacing mechanism, or that fresh water-ice in the outer Solar System can persist for gigayear timescales.

Background: We test the hypothesis that oropharyngeal leak pressure (OLP) and fibreoptic position (FP) are stable for the laryngeal mask airway (LMA) during anaesthesia with and without nitrous oxide. Methods: Forty paralysed anaesthetised patients (ASA 1-2, aged 18-80) were randomly allocated to receive 100% oxygen (O group) or 33% oxygen in nitrous oxide (O-NO group) for maintenance. In vivo intracuff pressure (CP) using a size 5 LMA was adjusted to 60 cm HO. OLP, FP and CP were measured every 5 min for 30 min. Results: CP was higher in the O-NO group than the O group, other than at time zero (all: P

To compare the performance of the intubating laryngeal mask airway (ILM) between fresh cadavers and anesthetised patients in terms of ease of insertion, oropharyngeal leak pressure (OLP), in-vivo intracuff pressure, anatomical position (assessed fibreoptically) and ease of fibreoptic-guided intubation.Twenty paralysed anesthetised patients and twenty cadavers (6-24 hr post-mortem) were studied. Groups were matched for height, weight and sex. Ease of insertion and ease of fibreoptic-guided intubation (number of insertion attempts and time to successful placement) were recorded. The OLP in-vivo intracuff pressure and anatomical position (judged fibreoptically) were measured at zero volume and after each additional 10 ml up to 40 ml.There were no differences in ease of insertion or ease of fibreoptic-guided intubation, OLP, in-vivo intracuff pressure or anatomic position between groups.We conclude that the performance of the ILM is similar for fresh cadavers and paralysed anesthetised patients. This suggests that the fresh cadaver is a suitable model for training and research.

In this randomised, crossover cadaver study, we determine the esophageal pressure (EP) at which water flow occurs between the upper esophagus and pharynx for the laryngeal mask airway (LMA) and cuffed oropharyngeal airway (COPA). Ten male and ten female cadavers were studied. The infusion set of a pressure controlled, continuous flow pump was inserted into the upper esophagus and ligated into place. The EP was increased in 2 cm H2O increments. This was performed without an airway device (controls) and over a range of cuff volumes for the LMA (0–40 ml) and COPA (0–60 ml). Regurgitation pressure (RP) was the EP at which fluid was first seen with a fibreoptic scope in the hypopharynx (controls) and above or below the cuff (LMA and COPA). The RP was higher for the LMA than for the COPA and controls (P < 0.0004), and RP was similar for COPA and controls. There was an increase in RP with increasing cuff volume for the LMA from 0 to 10 ml (P < 0.0001). There were no increases in RP with increasing cuff volume for the COPA. The EP at which fluid leaked above and below the cuff was similar for the LMA at all cuff volumes. The EP at which fluid leaked above the cuff was higher than below the cuff for the COPA when the cuff volume was 40 ml (P < 0.0001). In fresh cadavers, the LMA provides better airway protection from fluid in the upper esophagus than the COPA.

We tested the hypothesis that the pressure exerted by the laryngeal mask airway (LMA) against the pharyngeal mucosa varied with neuromuscular block, mode of ventilation and the respiratory cycle. We studied 20 anaesthetized adult patients. Microchip sensors were attached to a size 5 LMA at locations approximately corresponding to the base of the tongue, hypopharynx, lateral pharynx, oropharynx, posterior pharynx and piriform fossa. Mucosal pressures were measured with an intracuff pressure of 60 cm H2O under four conditions during anaesthesia using 2.0 MAC of sevoflurane: (1) apnoeic, non-paralysed; (2) spontaneously breathing, non-paralysed; (3) ventilated, paralysed and (4) non-ventilated, paralysed. In conditions (2) and (3), mucosal pressures were measured at the end of inspiration and expiration. Mean mucosal pressure was less than 10 cm H2O at all locations. There were no significant changes in mucosal pressure at any location between the four conditions. There was no variation between inspiration and expiration. With an intracuff pressure of 60 cm H2O in these circumstances, mucosal pressures were much less than considered safe for prolonged tracheal intubation.

We conducted a randomised cross-over study of 20 patients to test the hypothesis that oropharyngeal leak pressure and the fibreoptic view differ between the cuffed oropharyngeal airway and laryngeal mask airway in paralysed patients. We also tested the design premise that inflation of the cuffed oropharyngeal airway cuff elevates the epiglottis from the posterior pharyngeal wall. Both airways were inserted into each patient in random order. Oropharyngeal leak pressure and fibreoptic view were documented at zero volume and after each additional 10 ml up to the maximum recommended volume for each device. The laryngeal mask had a higher maximum (23 vs. 16 cmHO, p = 0.03), minimum (9 vs. 2 cmHO, p < 0.02) and overall (17 vs. 9 cmHO, p < 0.001) oropharyngeal leak pressure compared with the cuffed oropharyngeal airway. The glottic inlet was visible more frequently with the laryngeal mask (96 vs. 39%, p < 0.0001). There was no elevation of the epiglottis from the posterior pharyngeal wall with the cuffed oropharyngeal airway. We conclude that the laryngeal mask forms a more effective seal and provides a better fibreoptic view of the glottic inlet than the cuffed oropharyngeal airway in paralysed patients. Inflation of the cuffed oropharyngeal airway cuff does not cause elevation of the epiglottis.

We present the case of the successful use of a ProSeal laryngeal mask airway in a severe obese 41-year-old women with a difficult airway, scheduled to undergo cardiac surgery (off-pump coronary artery bypass). Two intubation attempts failed and face mask ventilation became impossible with rapidly falling peripheral oxygen saturation. A ProSeal laryngeal airway was railroaded over a tracheal tube guide, a gastric tube was inserted along the drain tube and the patient underwent positive pressure ventilation, resulting in normal gas exchange and an oropharyngeal leak pressure40 cm H2O. The decision was taken to proceed with the ProSeal as the airway during the surgical intervention. Surgery was uneventful and the ProSeal was removed on the ICU three hours later. This case reports illustrates the successful use of a guided insertion of the ProSeal laryngeal mask for airway rescue in cardiac surgery.

We have assessed a new method to evacuate saline completely from the laryngeal mask airway (LMA) cuff and tested the hypothesis that intracuff pressures, fibreoptic position and oropharyngeal leak pressures are similar for saline compared with air during nitrous oxide-oxygen anaesthesia. Eight size 4 LMA were inflated with saline 30 ml. After syringe evacuation, median residual weight was 0.56 (range 0.24-0.98) g; after additional manual cuff squeezing it was 0.26 (0.21-0.35) g; and after drying for 12 h at 60 degrees C with the valve open it was -0.02 (-0.05-0.04) g. Pressure-volume curves of four size 3-5 LMA showed that compliance was lower for the saline-filled cuff. A clinical study of 20 patients allocated randomly to have saline or air in the cuff showed a significant increase in intracuff pressure with air, but not saline, during nitrous oxide-oxygen anaesthesia. The fibreoptic position of the LMA changed more frequently in the air, compared with the saline-filled group (four of 10 vs none of 10; P = 0.04). Oropharyngeal leak pressures were similar between groups. We conclude that the saline-inflated LMA cuff was reliably emptied and more stable in terms of intracuff pressures and possibly fibreoptic position. Filling the LMA cuff with saline is a viable option during laser surgery to the airway.

We tested the hypothesis that, in patients with clear airways, the anatomical position of three single-use extraglottic airway devices is similar. The airways studied were: the laryngeal mask airway unique (LMA-U), the Softseal laryngeal mask airway (SS-LM) and the Cobra perilaryngeal airway (Cobra-PLA). Three hundred spontaneously breathing patients were randomly allocated to have their airway managed using one of these three supraglottic airway devices. A rigid endoscope was passed down the airway tube and the following anatomical assessments were made: position of the epiglottis; position of the glottis; and position of the cuff. The epiglottis was more frequently visible with the LMA-U than with the SS-LM (76 vs 57%, p = 0.006) and with the LMA-U than with the Cobra-PLA (76 vs 46%, p0.0001). The epiglottis was in contact with the mask aperture bars in 25% of patients, and in 34% of these, the epiglottis was seen to be herniated through the aperture bars. Herniation of the epiglottis through the mask aperture bars occurred more frequently with the Cobra-PLA than the LMA-U (8 vs 3%, p = 0.008). The vocal cords and arytenoids were more frequently visible with the LMA-U and SS-LM than with the Cobra-PLA (both p0.006). Herniation of the arytenoids through the mask aperture bars was more frequently seen with the Cobra-PLA than with the LMA-U (8 vs 0%, p = 0.004). The position of the cuff was optimal for the LMA-U and SS-LM in 90% and 93% of patients, respectively. The cuff was more frequently in the midline with the LMA-U than with the SS-LM (p = 0.002). We conclude that the anatomical position of the LMA-U and SS-LMA is superior to that of the Cobra-PLA in patients with clear airways. The mask aperture bars probably have no anatomical utility and predispose to herniation of the pharyngeal structures.

In this three-stage study, we test the hypothesis that supplementary cleaning with potassium permanganateor =4 mg.l(-1) eliminates protein and particle contamination from the reusable Classic laryngeal mask airway. The first stage involved supplementary cleaning of 70 1 x 1 cm segments from deliberately contaminated laryngeal mask airways using potassium permanganate at 0, 2, 4, 8, 16, 32 and 64 mg.l(-1) and testing for protein staining. This showed that the lowest concentration required to eliminate protein contamination was 8 mg.l(-1). The second stage involved supplementary cleaning of 50 used laryngeal mask airways with either potassium permanganate 8 mg.l(-1) or saline and testing for protein staining. This showed that protein contamination was lower in the potassium permanganate group (p0.00001): all laryngeal mask airways in the control group and none in the potassium permanganate group were contaminated. The third stage involved scanning electron microscopic examination of 1 x 1 cm segments from three laryngeal mask airways used in the control group, three from the potassium permanganate group, plus three brand new laryngeal mask airways. The mean density ofor =1 mum surface particles was lower in the potassium permanganate 8 mg.l(-1) than the control group (21 vs. 121 .cm(-2), p0.0001) and was similar to brand new laryngeal mask airways (24 .cm(-2)). We conclude that supplementary cleaning with potassium permanganate 8 mg.l(-1) eliminates protein deposits from reusable laryngeal mask airways and reduces particle contamination to similar levels to brand new laryngeal mask airways.

We determine the feasibility of using the intubating laryngeal mask airway Fastrach (ILM) as a ventilatory device during emergence from anesthesia after use as an airway intubator in patients undergoing carotid endarterectomy. Thirty-five patients (ASA 2-3, 53-84 yr) were studied. Induction was with midazolam/fentanyl/etomidate and maintenance was with sevoflurane 1-2% in O2 33-50% and N2O. Neuromuscular blockade was with cisatracurium. Tracheal intubation was with a flexible lightwand via the ILM. After successful intubation, the ILM remained in the pharynx, but with the cuff deflated. After surgery, but before anesthesia was discontinued, baseline cardiovascular variables were recorded. The ILM cuff was then reinflated, the tracheal tube removed, the anesthesia breathing system connected to the ILM and anesthesia discontinued. Any changes in the cardiovascular variables greater than +/- 20% baseline values were noted from cuff reinflation to 1 minute after ILM removal. Any adverse respiratory (laryngospasm, coughing, gagging, stridor, SpO294%, end-tidal carbon dioxide45 mmHg, regurgitation/aspiration) or electrocardiographic (ST segment or rhythm changes) events were also noted. Patients were questioned about postoperative sore throat at 2 and 24 hr. ILM insertion and intubation through the ILM were successful in all patients. Adequate ventilation was achieved in all patients before intubation and after extubation. The mean (range) time taken from cuff reinflation to ILM removal was 9 (5-21) min. The rate pressure product remained within +/- 20% baseline values in all patients. There were no adverse respiratory or electrocardiographic events. There were no adverse neurological events. The surgical field was satisfactory. Postoperative sore throat occurred in 14% at 2 hr and 0% at 24 hr. We conclude that the ILM can be used as a ventilatory device for emergence from anesthesia after use as an airway intubator for carotid endarterectomy.

We assessed the effectiveness of a 5-microm filter in reducing propofol-induced pain and determined whether any reduction is due to removal of contaminants or an alteration in flow characteristics. A total of 120 unpremedicated women (ASA 1-3, aged 18-70 yr) were randomly allocated to one of three equal-sized groups. In group A, propofol was drawn up and injected through an unfiltered plastic cannula. In group B, propofol was drawn up through a 5-microm filter needle and injected through an unfiltered plastic cannula. In group C, propofol was drawn up and injected through a 5-microm filter needle. Unmodified propofol from a 20-ml rubber topped vial at room temperature was used. A 22-g cannula was inserted into the largest visible vein on the dorsum of the non-dominant hand. Propofol was administered at 0.5 ml.s-1 and patients were asked about pain every 10 s until unresponsive, by a blinded observer. The pain score for the patient was the taken as the most severe pain documented. The frequency and severity of pain were similar among groups. We conclude that a 5-microm filter does not reduce pain associated with injection of propofol drawn from a vial with a rubber bung.

Twenty children aged 2-66 months were randomly allocated for airway management with either the laryngeal mask airway or uncuffed tracheal tube using intermittent positive pressure ventilation with a tidal volume of 8 ml.kg-1 and a respiratory rate adjusted to maintain end-expiratory carbon dioxide concentration at 5.3 kPa. Induction was with fentanyl/propofol and maintenance was with sevoflurane 2.5% in oxygen/air. The airway device was removed when the patients were awake and the patients were transferred to the postanaesthesia care unit 10 min later. Air was sampled from a point 1.5 m above the floor at a location remote from the ventilation outlet and analysed using a proton-transfer-reaction mass spectrometer capable of continuous trace gas analysis at the parts per billion volume (ppbv) level. The concentration of sevoflurane was recorded every minute during three consecutive phases: for 5 min before the introduction of sevoflurane (background); after introduction of sevoflurane until removal of the airway device (intra-operative); and every minute after removal until the concentration returned to background levels. Median (interquartile range [range]) intra-operative sevoflurane concentrations were 200-400 times higher than background values for the laryngeal mask airway 1 (1-2 [0-3]) ppbv vs. 404 (278-523 [83-983]) ppbv, respectively, and the tracheal tube 2 (1-3 [0-5]) ppbv vs. 396 (204-589 [107-1735]) ppbv (both p0.0001), and returned to background values within 5 min of removal. There were no differences in sevoflurane concentration between devices intra-operatively or after removal. The performance of the proton-transfer-reaction mass spectrometer was identical at the start and end of the 30-day study. We conclude that peri-operative sevoflurane concentration in a modern operating theatre is similar for the laryngeal mask airway and the uncuffed tracheal tube in paediatric patients receiving intermittent positive pressure ventilation. Intra-operative sevoflurane concentrations are five times lower than occupational safety limit requirements, and 1000 times lower 5 min after removal of the airway device with the patient awake. The proton-transfer-reaction mass spectrometer has potential for monitoring air quality in the operating theatre.

We report a case of mechanical closure of the vocal cords with the laryngeal mask airway ProSeal (PLMA) in an anaesthetized, paralysed 59-yr-old, 88 kg female undergoing lower-limb vascular surgery. Near-complete airway obstruction developed after a size-5 PLMA was inserted and the cuff inflated with 20 ml of air. Fibreoptic inspection revealed that the PLMA was correctly positioned, but the vocal cords were closed. Withdrawal of air from the cuff and/or moving the head and neck into the sniffing position resolved this problem.

We determined (a) the haemodynamic responses to intubating laryngeal mask (ILM) airway insertion/intubation and removal in anaesthetized patients, and (b) whether the timing of ILM removal influences these responses. One-hundred and twenty patients without cardiovascular disease were studied. ILM airway insertion/intubation was 5 min after induction with propofol 2 mg kg(-1) and maintenance of anaesthesia with sevoflurane 2% in oxygen 33% and nitrous oxide. Patients were randomly assigned for removal of the intubating laryngeal mask airway at 1, 3 and 5 min after successful intubation. Systolic and diastolic arterial pressures and heart rate were recorded preinduction (baseline), before ILM airway insertion/intubation, at 1-min intervals after insertion/intubation, and at 1-min intervals for 5 min after ILM removal. ILM insertion was successful at the first attempt in all patients, but 46 patients required more than one intubation attempt. Compared with baseline values, there were no increases in systolic or diastolic arterial pressure, but there was an increase in heart rate 1 min after ILM insertion/intubation (9%, P0.001) and 1 min after ILM removal (8%, P0.01). There was a significant increase in systolic and diastolic pressures and heart rate 1 min after ILM insertion/intubation (30%, 31% and 15%; all: P0.002) compared with before ILM insertion/intubation values and 1 min after ILM removal (9%, 8% and 7%; all P0.05) compared with 1 min after ILM insertion/intubation values. Removal of the ILM 1 min after successful intubation resulted in higher arterial pressure compared with removal at 3 min (systolic arterial pressure 10% higher for 1 min, P = 0.01) and 5 min (systolic arterial pressure 10-23% higher for 3 min, P0.01; diastolic arterial pressure 10-20% higher for 4 min, P0.02), but there were no differences in heart rate between groups. Systolic and diastolic arterial pressures were greater if more than one intubation attempt was required. Early removal or multiple intubation attempts did not exceed baseline haemodynamic values. We conclude that ILM insertion/intubation and removal in anaesthetized patients produces little or no haemodynamic response, even if multiple intubation attempts are required. The timing of removal exerts a small, but clinically unimportant influence on these responses.