Preventing unrecognised oesophageal intubation: a consensus guideline from the Project for Universal Management of Airways and international airway societies

Across multiple disciplines undertaking airway management globally, preventable episodes of unrecognised oesophageal intubation result in profound hypoxaemia, brain injury and death. These events occur in the hands of both inexperienced and experienced practitioners. Current evidence shows that unrecognised oesophageal intubation occurs sufficiently frequently to be a major concern and to merit a co-ordinated approach to address it. Harm from unrecognised oesophageal intubation is avoidable through reducing the rate of oesophageal intubation, combined with prompt detection and immediate action when it occurs. The detection of 'sustained exhaled carbon dioxide' using waveform capnography is the mainstay for excluding oesophageal placement of an intended tracheal tube. Tube removal should be the default response when sustained exhaled carbon dioxide cannot be detected. If default tube removal is considered dangerous, urgent exclusion of oesophageal intubation using valid alternative techniques is indicated, in parallel with evaluation of other causes of inability to detect carbon dioxide. The tube should be removed if timely restoration of sustained exhaled carbon dioxide cannot be achieved. In addition to technical interventions, strategies are required to address cognitive biases and the deterioration of individual and team performance in stressful situations, to which all practitioners are vulnerable. These guidelines provide recommendations for preventing unrecognised oesophageal intubation that are relevant to all airway practitioners independent of geography, clinical location, discipline or patient type.

Mortality by cause of death during year 1 of the COVID-19 pandemic in a cohort of older adults from Baltimore Maryland who have injected drugs

BACKGROUND

In 2020, the first year of the COVID-19 pandemic, overdose deaths increased. However, no studies have characterized changes in mortality during the pandemic in a well-characterized cohort of people who use drugs in active follow-up at the time of pandemic onset.

DESIGN

We compared all-cause and cause-specific mortality in the first year of the pandemic (Mar-Dec 2020) to the five years preceding (Jan 2015-Feb 2020), among participants in the AIDS Linked to the IntraVenous Experience (ALIVE) study: a community-recruited cohort of adults from Baltimore who have injected drugs. 3510 participants contributed 17,498 person-years [py] of follow-up time. Cause and dates of death were ascertained through the National Death Index. Comparisons were made for the full cohort and within subgroups with potentially differential levels of vulnerability.

RESULTS

All-cause mortality in 2020 was 39.6 per 1000 py, as compared to 37.2 per 1000 py pre- pandemic (Adjusted Incidence Rate Ratio = 1.09, 95%: confidence interval: 0.84-1.41). Increases were mostly attributable to chronic disease deaths; injury/poisoning deaths did not increase. No pre-post differences were statistically significant.

CONCLUSION

In this exploratory analysis of an older cohort of urban-dwelling adults who have injected drugs, mortality changes during the first year of the pandemic differed from national trends and varied across potentially vulnerable subgroups. More research is needed to understand determinants of increased risk of mortality during the pandemic among subgroups of people who use drugs.

Risks to healthcare workers following tracheal intubation of patients with COVID-19: a prospective international multicentre cohort study

Healthcare workers involved in aerosol‐generating procedures, such as tracheal intubation, may be at elevated risk of acquiring COVID‐19. However, the magnitude of this risk is unknown. We conducted a prospective international multicentre cohort study recruiting healthcare workers participating in tracheal intubation of patients with suspected or confirmed COVID‐19. Information on tracheal intubation episodes, personal protective equipment use and subsequent provider health status was collected via self‐reporting. The primary endpoint was the incidence of laboratory‐confirmed COVID‐19 diagnosis or new symptoms requiring self‐isolation or hospitalisation after a tracheal intubation episode. Cox regression analysis examined associations between the primary endpoint and healthcare worker characteristics, procedure‐related factors and personal protective equipment use. Between 23 March and 2 June 2020, 1718 healthcare workers from 503 hospitals in 17 countries reported 5148 tracheal intubation episodes. The overall incidence of the primary endpoint was 10.7% over a median (IQR [range]) follow‐up of 32 (18–48 [0–116]) days. The cumulative incidence within 7, 14 and 21 days of the first tracheal intubation episode was 3.6%, 6.1% and 8.5%, respectively. The risk of the primary endpoint varied by country and was higher in women, but was not associated with other factors. Around 1 in 10 healthcare workers involved in tracheal intubation of patients with suspected or confirmed COVID‐19 subsequently reported a COVID‐19 outcome. This has human resource implications for institutional capacity to deliver essential healthcare services, and wider societal implications for COVID‐19 transmission.

Late Holocene volcanic and anthropogenic mercury deposition in the western Central Andes (Lake Chungará, Chile)

Volcanism is one of the major natural processes emitting mercury (Hg) to the atmosphere, representing a significant component of the global Hg budget. The importance of volcanic eruptions for local-scale Hg deposition was investigated using analyses of Hg, inorganic elemental tracers, and organic biomarkers in a sediment sequence from Lake Chungará (4520 m a.s.l.). Environmental change and Hg deposition in the immediate vicinity of the Parinacota volcano were reconstructed over the last 2700 years, encompassing the pre-anthropogenic and anthropogenic periods. Twenty eruptions delivering large amounts of Hg (1 to 457 μg Hg m^-2 yr^-1 deposited at the timescale of the event) were locally recorded. Peaks of Hg concentration recorded after most of the eruptions were attributed to a decrease in sedimentation rate together with the rapid re-oxidation of gaseous elemental Hg and deposition with fine particles and incorporation into lake primary producers. Over the study period, the contribution of volcanic emissions has been estimated as 32% of the total Hg input to the lake. Sharp depletions in primary production occurred at each eruption, likely resulting from massive volcaniclastic inputs and changes in the lake-water physico-chemistry. Excluding the volcanic deposition periods, Hg accumulation rates rose from natural background values (1.9 ± 0.5 μg m^-2 yr^-1) by a factor of 2.3 during the pre-colonial mining period (1400-900 yr cal. BP), and by a factor of 6 and 7.6, respectively, during the Hispanic colonial epoch (400-150 yr cal. BP) and the industrial era (~140 yr cal. BP to present). Altogether, the dataset indicates that lake primary production has been the main, but not limiting, carrier for Hg to the sediment. Volcanic activity and climate change are only secondary drivers of local Hg deposition relative to the magnitude of regional and global anthropogenic emissions.

Education in airway management

In airway management, poor judgment, education and training are leading causes of patient morbidity and mortality. The traditional model of medical education, which relies on experiential learning in the clinical environment, is inconsistent and often inadequate. Curriculum change is underway in many medical organisations in an effort to correct these problems, and airway management is likely to be explicitly addressed as a clinical fundamental within any new anaesthetic curriculum. Competency-based medical education with regular assessment of clinical ability is likely to be introduced for all anaesthetists engaged in airway management. Essential clinical competencies need to be defined and improvements in training techniques can be expected based on medical education research. Practitioners need to understand their equipment and diversify their airway skills to cope with a variety of clinical presentations. Expertise stems from deliberate practice and a desire constantly to improve performance with a career-long commitment to education.

Failure to ventilate with supraglottic airways after drowning

We report the failure of an i-gel and an Ambu AuraOnce supraglottic airway to ventilate a drowning victim. Failure was attributed to changes in lung physiology following submersion and inhalation of water that may have required ventilation pressures up to 40 cmH2O to treat the victim's hypoxaemia. The ease of use and rapid insertion of supraglottic airways without interrupting cardiac compression has prompted recommendations for their use during resuscitation. The relatively low leak pressures attainable from many supraglottic airways, however may cause inadequate lung ventilation and entrainment of air into the stomach when these devices are used in drowning victims.

Equipment to manage a difficult airway during anaesthesia

Airway complications are a leading cause of morbidity and mortality in anaesthesia. Effective management of a difficult airway requires the timely availability of suitable airway equipment. The Australian and New Zealand College of Anaesthetists has recently developed guidelines for the minimum set of equipment needed for the effective management of an unexpected difficult airway (TG4 [2010] www.anzca.edu.au/resources/professionaldocuments). TG4 [2010] is based on expert consensus, underpinned by wide consultation and an extensive review of the available evidence, which is summarised in a Background Paper (TG4 BP [2010] www.anzca.edu.au/ resources/professional-documents). TG4 [2010] will be reviewed at the end of one year and thereafter every five years or more frequently if necessary. The current paper is reproduced directly from the Background Paper (TG4 BP [2010]).

Broad dissemination of plasmid-mediated quinolone resistance genes in sediments of two urban coastal wetlands

Contamination of soil and water with antibiotic-resistant bacteria may create reservoirs of antibiotic resistance genes that have the potential to negatively impact future public health through horizontal gene transfer. The plasmid-mediated quinolone resistance genes qnrA, qnrB, qnrS, qepA, and aac(6')-Ib-cr were detected by PCR amplification of metagenomic DNA from surface sediments of the Tijuana River Estuary, a sewage-impacted coastal wetland along the U.S.-Mexico border; sediments of Famosa Slough, a nearby urban wetland that is largely unaffected by sewage, contained only qnrB, qnrS, and qepA. The number of PCR-positive sites and replicates increased in both wetlands after rainfall. Real-time quantitative PCR revealed a significant increase (p < 0.0005) in qnrA abundance (copies per gram sediment or per 16S rDNA copy) in Tijuana River Estuary sediments immediately following rainfall, but no significant change was measured at Famosa Slough (p > 0.1). Nucleotide sequences of cloned qnrA amplicons were all affiliated with qnrA genes found on plasmids of clinical isolates with one exception that was most similar to the chromosomal qnrA gene found in Shewanella algae. Our results suggest that urban wetlands may become reservoirs of antibiotic resistance genes, particularly where wastewater is improperly managed.

Constraints on the formation of sedimentary dolomite

The experimental replacement of calcite and aragonite by dolomite under a variety of conditions indicates that dolomitization can take place in marine and lacustrine environments under two conditions: (i) low dissolved sulfate concentrations and (ii) insubstantial contemporaneous silica diagenesis. Common sites for dolomite formation are areas where the dissolved sulfate concentration is reduced by microbial sulfate reduction, through the mixing of seawater with large amounts of fresh water, or where low-sulfate alkaline lacustrine environments prevail. Even under these conditions, dolomite formation may be inhibited by the concurrent transformation of opal-A (amorphous silica) to opal-CT (disordered cristobalite and tridymite), whereas the subsequent transformation of opal-CT to quartz favors the formation of dolomite.

Functional gracilis flap in thenar reconstruction

Restoration of lost opposition in the context of significant thenar soft tissue defects represents a tremendous reconstructive challenge. Free functioning muscle transfer has been described in this context and has the advantage of providing both a functioning muscle unit as well as soft tissue coverage in a single reconstructive procedure. It adds to the injured limb, and by sparing donor tendons avoids the need for re-education of motor function. We describe the use of a free innervated gracilis muscle flap for functional thenar reconstruction in two unique cases following extensive traumatic loss of thenar skin and musculature. Crucially, in each case, the recurrent motor branch of the median nerve had been destroyed at its point of insertion into the thenar muscle remnants.

AIM

To date, the main reported disadvantages of free functioning muscle transfer in thenar reconstruction include difficult flap dissections, donor site morbidity, inadequate strength and excursion of the transplanted muscle and excessively bulky flaps. Our aim was, as far as possible, to address these issues.

SURGICAL PROCEDURE

Each thenar defect was measured and a corresponding segment of gracilis muscle, measured in situ, was raised on the proximal neurovascular pedicle. End-side microvascular anastomosis was performed between the medial circumflex femoral artery and the radial artery. The venae comitantes of the pedicle were anastomosed end-end with those of the radial artery and also with the cephalic vein. Epineural anastomosis was performed between the motor branch of the obturator nerve and the recurrent motor branch of the median nerve. Each flap was covered with a split thickness skin graft.

RESULTS

Both flaps survived without any complication. Both patients regained excellent voluntary thumb opposition, sufficient to allow return to full-time employment, and had restoration of sufficient thenar bulk. This was achieved with minimal donor site morbidity.

CONCLUSIONS

Restoration of lost opposition, in the context of significant thenar soft tissue defects, can be achieved using a free functional gracilis flap. This produces clinically excellent functional results and can be carried out as a single stage reconstructive procedure. This is a novel application of a tremendously versatile donor muscle in functioning free muscle transfer.

Early warming of tropical South America at the last glacial-interglacial transition

Glaciation in the humid tropical Andes is a sensitive indicator of mean annual temperature. Here, we present sedimentological data from lakes beyond the glacial limit in the tropical Andes indicating that deglaciation from the Last Glacial Maximum led substantial warming at high northern latitudes. Deglaciation from glacial maximum positions at Lake Titicaca, Peru/Bolivia (16 degrees S), and Lake Junin, Peru (11 degrees S), occurred 22,000 to 19,500 calendar years before the present, several thousand years before the Bølling-Allerød warming of the Northern Hemisphere and deglaciation of the Sierra Nevada, United States (36.5 degrees to 38 degrees N). The tropical Andes deglaciated while climatic conditions remained regionally wet, which reflects the dominant control of mean annual temperature on tropical glaciation.

Low-temperature growth of nanostructured diamond films

Nanostructured diamond films are grown on a titanium alloy substrate using a two-step deposition process. The first step is performed at elevated temperature (820 degrees C) for 30 min using a H2/CH4/N2 gas mixture to grow a thin (approximately 600 nm) nanostructured diamond layer and to improve film adhesion. The remainder of the deposition involves growth at low temperature (< 600 degrees C) in a H2/CH4/O2 gas mixture. The continuation of the smooth nanostructured diamond film growth during low-temperature deposition is confirmed by in situ laser reflectance interferometry, atomic force microscopy, micro-Raman spectroscopy, and surface profilometry. Similar experiments performed without the initial nanostructured diamond layer resulted in poorly adhered films with a more crystalline appearance and a higher surface roughness. This low-temperature deposition of nanostructured diamond films on metals offers advantages in cases where high residual thermal stress leads to delamination at high temperatures.

Tropical climate changes at millennial and orbital timescales on the Bolivian Altiplano

Tropical South America is one of the three main centres of the global, zonal overturning circulation of the equatorial atmosphere (generally termed the 'Walker' circulation). Although this area plays a key role in global climate cycles, little is known about South American climate history. Here we describe sediment cores and down-hole logging results of deep drilling in the Salar de Uyuni, on the Bolivian Altiplano, located in the tropical Andes. We demonstrate that during the past 50,000 years the Altiplano underwent important changes in effective moisture at both orbital (20,000-year) and millennial timescales. Long-duration wet periods, such as the Last Glacial Maximum--marked in the drill core by continuous deposition of lacustrine sediments--appear to have occurred in phase with summer insolation maxima produced by the Earth's precessional cycle. Short-duration, millennial events correlate well with North Atlantic cold events, including Heinrich events 1 and 2, as well as the Younger Dryas episode. At both millennial and orbital timescales, cold sea surface temperatures in the high-latitude North Atlantic were coeval with wet conditions in tropical South America, suggesting a common forcing.

The history of South American tropical precipitation for the past 25,000 years

Long sediment cores recovered from the deep portions of Lake Titicaca are used to reconstruct the precipitation history of tropical South America for the past 25,000 years. Lake Titicaca was a deep, fresh, and continuously overflowing lake during the last glacial stage, from before 25,000 to 15,000 calibrated years before the present (cal yr B.P.), signifying that during the last glacial maximum (LGM), the Altiplano of Bolivia and Peru and much of the Amazon basin were wetter than today. The LGM in this part of the Andes is dated at 21,000 cal yr B.P., approximately coincident with the global LGM. Maximum aridity and lowest lake level occurred in the early and middle Holocene (8000 to 5500 cal yr B.P.) during a time of low summer insolation. Today, rising levels of Lake Titicaca and wet conditions in Amazonia are correlated with anomalously cold sea-surface temperatures in the northern equatorial Atlantic. Likewise, during the deglacial and Holocene periods, there were several millennial-scale wet phases on the Altiplano and in Amazonia that coincided with anomalously cold periods in the equatorial and high-latitude North Atlantic, such as the Younger Dryas.

Retest reliability of the temporal and distance characteristics of hemiplegic gait using a footswitch system

Using a footswitch system, the retest reliability of the temporal and distance parameters of gait was investigated within a session for 22 stroke patients in the early phase of rehabilitation. High to very high reliability was found for the temporal and distance parameters of gait, and the temporal symmetry index based on the difference in single-limb support duration between each leg (r = 0.85 to 0.98; intraclass correlation coefficients (ICC)(2,1) = 0.82 to 0.98). Significant differences were found between the two trials for velocity, stride length, and total double support (p < .05). Despite the high reliability coefficients, 95% confidence intervals, which take into account the random and systematic error, were wide for all parameters. These wide confidence intervals indicate that the use of two consecutive measurements for interpreting an individual patient's change would not be a sensitive method for monitoring progress or deterioration during rehabilitation. Strategies that may improve the clinical usefulness of temporal and distance gait measures in stroke rehabilitation are discussed. These include further reducing error sources, increasing data collection per measurement, using serial measurements on each patient, or using less rigorous confidence intervals.

Treadmill gait retraining following fractured neck-of-femur

The rehabilitation outcome of two methods of gait retraining, was studied in 40 elderly women who had fractured the neck-of-femur. Twenty control subjects received conventional gait retraining, and 20 experimental subjects participated in a treadmill gait retraining program. Rehabilitation outcome was determined by temporal-distance gait parameters and mobility level (house-bound, limited, or unlimited). Muscle strength and range of movement of the lower limb were measured. Previously reported predictors of poor outcome (age, prefracture mobility, admission from sites other than own home, availability of caring person, type of ambulatory aid, presence or absence of senile dementia, and number of concomitant medical diseases) were recorded. Subjects were assessed on admission to the gait retraining program and at discharge from hospital. A 3 x 2 chi-square analysis on discharge mobility level showed the mobility level of the treadmill group to be significantly (p less than .05) higher than the mobility level attained by the control group. Analysis of variance showed no significant differences between the two groups at either assessment time. However, a significant increase in within-group variance from admission to discharge (p less than .01) was noted, and this led to the analysis of a subgroup containing six pairs of subjects matched for number of predictors of poor outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Gait recovery pattern of unilateral lower limb amputees during rehabilitation

The aim of this study was to determine the rate at which gait recovery as measured by temporal distance factors (velocity and symmetry) occurs in unilateral lower limb amputees. A microcomputer foot switch system was used to record the gait patterns of twenty subjects, mean age 65.1 years. The initial measurement was taken when the subject was capable of walking 6 metres with an interim prosthesis within the parallel bars. The patient sample as a whole was analyzed and subjects were further divided into four groups, depending on ambulatory aid required at discharge. Group A, n = 3 used no aid, Group B, n = 5 used a single stick, Group C, n = 6 used 2 single sticks and Group D, n = 5 required frames. A one way analysis of variance (F = 4.55, p = 0.02) showed a significant difference between the Groups, (A and D, B and D, C and D). The major velocity increase occurs within the first 30 days of the gait training programme. Overall about 55% increase in velocity can be expected within the first fifteen day period followed by an additional 30% between days 15-30. A moderately strong correlation (r = 0.78) was found between initial and discharge velocity. The correlation between initial and discharge symmetry was weaker (r = 0.50).

Intraocular penetration of rifampin after oral administration

Rifampin, the most potent anti-staphylococcal drug known, was examined for its penetration into the aqueous and vitreous of rabbits after a single oral dose of 150 mg, 300 mg, or 600 mg. Maximum levels after the 150 mg dose were achieved at 4 h and were 4.2 micrograms/ml in the aqueous and 2.2 micrograms/ml in the vitreous. After the 300 mg dose, maximum levels were also achieved at 4 h, and were 5.0 micrograms/ml in the aqueous and 2.6 micrograms/ml in the vitreous. The 600 mg dose produced maximum levels at 6 h after administration, with 20.0 micrograms/ml in the aqueous and 15.2 micrograms/ml in the vitreous. These levels exceed the minimum inhibitory concentration for many microorganisms and suggest additional investigation into possible applications of systemic rifampin in the prophylaxis and treatment of bacterial endophthalmitis.

Local immunostimulation of the bovine mammary gland with interleukin-2

One day after drying off, miniosmotic pumps releasing interleukin-2 were implanted into teat cisterns of six Jersey cows. Each cow had two quarters with (sensitized) and without (unsensitized) chronic Staphylococcus aureus infection. At 1 and 3 wk after implantation, three cows were sacrificed and mammary tissues processed to examine the cytological response to interleukin-2. Concentrations of lymphoid cells were determined in tissues lining teat and gland cistern linings, and plasma cells were characterized by Ig class. For total lymphoid cell and IgG1 and IgG2 plasma cell concentrations, sensitized placebo quarters and unsensitized interleukin-2 quarters were similar, indicating interleukin-2 stimulated a cellular immune response equal to that of quarters infected with S. aureus. Greatest response was observed in sensitized interleukin-2 quarters, suggesting that the cytokine was more effective in quarters with prior exposure to S. aureus antigens. Greater numbers of lymphocytes and macrophages were found in secretions of interleukin-2 quarters than in secretion of control quarters. Local interleukin-2 immunostimulation may supplement immunization procedures and enhance protection against natural S. aureus challenge.

Host defences in the upper genital tract of the female: studies in a murine system

Mechanical and cellular factors which maintain sterility in the fallopian tube were studied in virgin, BALB/c mice. Quantitative cultures of homogenates from ovary/periovarian sac, fallopian tube and uterine horn were obtained at various times after intratubal injection of 6 X 10(7) Escherichia coli (E. coli) by micropuncture. Immediately post-injection, significantly higher bacterial counts were obtained from fallopian tube than from uterine horn, indicating a functional barrier at the uterotubal junction. Viable E. coli were usually absent from the genital tract within 7 days. Reduction in bacterial counts was significant at 24 h post-injection. Ligation of the uterine horn and/or induction of leucopenia prior to injection were associated with decreased bacterial clearance at 24 h. Histology of samples from normal, injected mice revealed marked polymorphonuclear leucocyte (PMNL) infiltration in response to E. coli, confirmed by quantitation of intralumenal PMNL. By 72 h post-injection, viable E. coli and PMNL containing phagocytosed particles were prominent in vaginal washings. No inflammatory response was elicited in leucopenic mice. We conclude that clearance of E. coli from the fallopian tube depends primarily on excretion through the lower genital tract and PMNL-associated bacterial activity.

Cost benefit analysis of screening spina bifida

Cost benefit analysis of establishing and running a mass serum alpha-fetoprotein (AFP) screening service for neural tube defects (NTDS) in the Auckland Hospital Board area has been undertaken and a cost benefit index derived. From a population of 14 066 pregnant women per year, assuming present booking patterns continue, 8017 women could be screened for NTDS. Such screening could reduce severe spina bifida in liveborn babies by 38.8 percent.

Contextual conditioning and the US preexposure effect in conditioned fear

A series of five experiments was carried out in which fear of context caused by exposure to shocks was manipulated by signaling the shocks with a discrete stimulus, signaling the days during which shocks occurred with a session-long stimulus, or switching the context between exposure and the subsequent test. All these manipulations influenced fear of the context in the manner predicted by the Rescorla-Wagner associative model. Following this, all the rats were given conditioning trials with shock and a different discrete stimulus. All preexposure treatments produced consistent and reliable interference with conditioning with the exception of signaling the shocks with a discrete stimulus, which greatly reduced interference. These results are interpreted as being consistent both with a cognitive explanation of the US exposure effect, which claims that animals learn that shocks are unpredictable during conditioning and this knowledge retards future conditioning when they are predictable, and with an adaptation explanation, which claims that unpredictable shocks produce chronic fear and this fear through either a change in adaptation level or through emotional exhaustion renders the shocks less reinforcing during the conditioning test.