Handling injectable medications in anaesthesia: Guidelines from the Association of Anaesthetists

Peri-operative medication safety is complex. Avoidance of medication errors is both system- and practitioner-based, and many departments within the hospital contribute to safe and effective systems. For the individual anaesthetist, drawing up, labelling and then the correct administration of medications are key components in a patient's peri-operative journey. These guidelines aim to provide pragmatic safety steps for the practitioner and other individuals within the operative environment, as well as short- to long-term goals for development of a collaborative approach to reducing errors. The aim is that they will be used as a basis for instilling good practice.

A vanguard randomised feasibility trial comparing three regimens of peri-operative oxygen therapy on recovery after major surgery

International recommendations encourage liberal administration of oxygen to patients having surgery under general anaesthesia, ostensibly to reduce surgical site infection. However, the optimal oxygen regimen to minimise postoperative complications and enhance recovery from surgery remains uncertain. The hospital operating theatre randomised oxygen (HOT-ROX) trial is a multicentre, patient- and assessor-blinded, parallel-group, randomised clinical trial designed to assess the effect of a restricted, standard care, or liberal peri-operative oxygen therapy regimen on days alive and at home after surgery in adults undergoing prolonged non-cardiac surgery under general anaesthesia. Here, we report the findings of the internal vanguard feasibility phase of the trial undertaken in four large metropolitan hospitals in Australia and New Zealand that included the first 210 patients of a planned overall 2640 trial sample, with eight pre-specified endpoints evaluating protocol implementation and safety. We screened a total of 956 participants between 1 September 2019 and 26 January 2021, with data from 210 participants included in the analysis. Median (IQR [range]) time-weighted average intra-operative Fi O2 was 0.30 (0.26-0.35 [0.20-0.59]) and 0.47 (0.44-0.51 [0.37-0.68]) for restricted and standard care, respectively (mean difference (95%CI) 0.17 (0.14-0.20), p < 0.001). Median time-weighted average intra-operative Fi O2 was 0.83 (0.80-0.85 [0.70-0.91]) for liberal oxygen therapy (mean difference (95%CI) compared with standard care 0.36 (0.33-0.39), p < 0.001). All feasibility endpoints were met. There were no significant patient adverse events. These data support the feasibility of proceeding with the HOT-ROX trial without major protocol modifications.

Implementing advance care plans in the peri-operative period, including plans for cardiopulmonary resuscitation: Association of Anaesthetists clinical practice guideline

Contemporary guidance takes a patient-centred approach and recommends discussing and planning treatments that should be considered, not just those that should be withheld. Although some organisations and communities still use specific DNACPR (do not attempt cardiopulmonary resuscitation) forms to recommend that cardiopulmonary resuscitation is not attempted, this approach has been shown to have disadvantages and is no longer regarded as best practice. The following guidelines have been produced in response to this change. They are designed to help anaesthetists, as part of the wider healthcare team, to implement and respond to advance care planning documents before and during procedures. The guidelines apply to all procedures, however minor and low risk they are considered to be, and the same ethical and legal principles apply to procedures carried out under local or regional anaesthesia and/or conscious sedation, as well as to those under general anaesthesia.

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

This assessment by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) provides the latest scientific update since our most recent comprehensive assessment (Photochemical and Photobiological Sciences, 2019, 18, 595-828). The interactive effects between the stratospheric ozone layer, solar ultraviolet (UV) radiation, and climate change are presented within the framework of the Montreal Protocol and the United Nations Sustainable Development Goals. We address how these global environmental changes affect the atmosphere and air quality; human health; terrestrial and aquatic ecosystems; biogeochemical cycles; and materials used in outdoor construction, solar energy technologies, and fabrics. In many cases, there is a growing influence from changes in seasonality and extreme events due to climate change. Additionally, we assess the transmission and environmental effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, in the context of linkages with solar UV radiation and the Montreal Protocol.

Environmental effects of stratospheric ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2019

This assessment, by the United Nations Environment Programme (UNEP) Environmental Effects Assessment Panel (EEAP), one of three Panels informing the Parties to the Montreal Protocol, provides an update, since our previous extensive assessment (Photochem. Photobiol. Sci., 2019, 18, 595-828), of recent findings of current and projected interactive environmental effects of ultraviolet (UV) radiation, stratospheric ozone, and climate change. These effects include those on human health, air quality, terrestrial and aquatic ecosystems, biogeochemical cycles, and materials used in construction and other services. The present update evaluates further evidence of the consequences of human activity on climate change that are altering the exposure of organisms and ecosystems to UV radiation. This in turn reveals the interactive effects of many climate change factors with UV radiation that have implications for the atmosphere, feedbacks, contaminant fate and transport, organismal responses, and many outdoor materials including plastics, wood, and fabrics. The universal ratification of the Montreal Protocol, signed by 197 countries, has led to the regulation and phase-out of chemicals that deplete the stratospheric ozone layer. Although this treaty has had unprecedented success in protecting the ozone layer, and hence all life on Earth from damaging UV radiation, it is also making a substantial contribution to reducing climate warming because many of the chemicals under this treaty are greenhouse gases.

Ozone-climate interactions and effects on solar ultraviolet radiation

This report assesses the effects of stratospheric ozone depletion and anticipated ozone recovery on the intensity of ultraviolet (UV) radiation at the Earth's surface. Interactions between changes in ozone and changes in climate, as well as their effects on UV radiation, are also considered. These evaluations focus mainly on new knowledge gained from research conducted during the last four years. Furthermore, drivers of changes in UV radiation other than ozone are discussed and their relative importance is assessed. The most important of these factors, namely clouds, aerosols and surface reflectivity, are related to changes in climate, and some of their effects on short- and long-term variations of UV radiation have already been identified from measurements. Finally, projected future developments in stratospheric ozone, climate, and other factors affecting UV radiation have been used to estimate changes in solar UV radiation from the present to the end of the 21^st century. New instruments and methods have been assessed with respect to their ability to provide useful and accurate information for monitoring solar UV radiation at the Earth's surface and for determining relevant exposures of humans. Evidence since the last assessment reconfirms that systematic and accurate long-term measurements of UV radiation and stratospheric ozone are essential for assessing the effectiveness of the Montreal Protocol and its Amendments and adjustments. Finally, we have assessed aspects of UV radiation related to biological effects and human health, as well as implications for UV radiation from possible solar radiation management (geoengineering) methods to mitigate climate change.

A Two Centre Observational Study of Simultaneous Pulse Oximetry and Arterial Oxygen Saturation Recordings in Intensive Care Unit Patients

The influence of variables that might affect the accuracy of pulse oximetry (SpO2) recordings in critically ill patients is not well established. We sought to describe the relationship between paired SpO2/SaO2 (oxygen saturation via arterial blood gas analysis) in adult intensive care unit (ICU) patients and to describe the diagnostic performance of SpO2 in detecting low SaO2 and PaO2. A paired SpO2/SaO2 measurement was obtained from 404 adults in ICU. Measurements were used to calculate bias, precision, and limits of agreement. Associations between bias and variables including vasopressor and inotrope use, capillary refill time, hand temperature, pulse pressure, body temperature, oximeter model, and skin colour were estimated. There was no overall statistically significant bias in paired SpO2/SaO2 measurements; observed limits of agreement were +/-4.4%. However, body temperature, oximeter model, and skin colour, were statistically significantly associated with the degree of bias. SpO2 <89% had a sensitivity of 3/7 (42.9%; 95% confidence intervals, CI, 9.9% to 81.6%) and a specificity of 344/384 (89.6%; 95% CI 86.1% to 92.5%) for detecting SaO2 <89%. The absence of statistically significant bias in paired SpO2/SaO2 in adult ICU patients provides support for the use of pulse oximetry to titrate oxygen therapy. However, SpO2 recordings alone should be used cautiously when SaO2 recordings of 4.4% higher or lower than the observed SpO2 would be of concern. A range of variables relevant to the critically ill had little or no effect on bias.

Fluid Administration, Vasopressor Use and Patient Outcomes in a Group of High-Risk Cardiac Surgical Patients Receiving Postoperative Goal-Directed Haemodynamic Therapy: A Pilot Study

The role of goal-directed therapy in high-risk cardiac surgical patients has not been determined. This study sought to observe the effect of a postoperative standardised haemodynamic protocol (SHP) on the administration of fluid and vasoactive drugs after high-risk cardiac surgery. This was an interventional pilot study. In 2010 to 2011, the SHP was introduced to the ICU at Wellington Regional Hospital, Wellington, New Zealand, for the perioperative management of patients undergoing high-risk cardiac surgery. A pulmonary artery catheter was inserted in the patients in the study group and fluids and supportive medications were provided in the ICU according to a protocol that targeted a cardiac index ≥2 l/min/m2, mixed venous oxygen saturation ≥60% and a mean arterial pressure of 65 to 75 mmHg. Data from 40 consecutive high-risk cardiac surgical patients assigned to this protocol were compared with a matched cohort of 40 consecutive high-risk cardiac surgical patients receiving ‘usual care’ in 2009. Baseline characteristics were similar in the two groups. There was no significant difference in the duration of noradrenaline infusion in the SHP cohort compared to historical controls (median [IQR] 18.5 hours [31.63] versus 18 hours [18.3]; P=0.35), despite patients receiving more fluid in their first 12 hours in the ICU (mean 4687 ml [SD±2284 ml] versus 1889 ml [SD±1344 ml]; P <0.001). The SHP cohort had a higher rate of reintubation (4 in 37 [10.8%] versus 0 in 40 [0%]; P=0.049). The SHP delivered significantly more fluid, but did not reduce the duration of noradrenaline infusion, compared to usual care.

Description of a new non-injectable connector to reduce the complications of arterial blood sampling

Arterial cannulation is associated with complications including bacterial contamination, accidental intra-arterial injection and blood spillage. We performed a series of audits and experiments to gauge the potential for these, as well as assess the possible contribution of a new device, the Needle-Free Arterial Non-Injectable Connector (NIC), in reducing these risks. The NIC comprises a needle-free connector that prevents blood spillage and a one-way valve allowing aspiration only; once screwed onto the side port of a three-way tap, the device can only be removed with difficulty. We performed a clinical audit of arterial monitoring systems in our intensive care unit, which showed an incidence of bacterial colonisation of five in 86 (6%) three-way tap ports. We constructed a manikin simulation experiment of the management of acute bradycardia, in which trainee doctors were required to inject atropine intravenously. Ten of 15 (66%) doctors injected the drug into the three-way tap of the arterial monitoring system rather than into the intravenous cannula or the central venous catheter. In a laboratory study, we replicated the arterial blood sampling and flushing sequence from a three-way tap, with the syringes attached either directly to the three-way tap port or to a NIC attached to the port. The first (discard) syringe attached to the three-way tap was contaminated with bacteria. Bacterial growth was found in 17 of 20 (85%) downstream flushed samples (corresponding to the patient's circulation) when the three-way tap was accessed directly, compared to none of 20 accessed via the NIC (p < 0.0001). Growth was found on all of 20 (100%) ports accessed directly compared to none of 20 accessed via the NIC (p < 0.0001). The NIC effectively prevents bacteria from contaminating sampling lines. As its design also prevents accidental intra-arterial injection, we suggest that it can reduce complications of arterial monitoring.

The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NO(x) emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.

Hidden flows and waste processing--an analysis of illustrative futures

An existing materials flow model is adapted (using Excel and AMBER model platforms) to account for waste and hidden material flows within a domestic environment. Supported by national waste data, the implications of legislative change, domestic resource depletion and waste technology advances are explored. The revised methodology offers additional functionality for economic parameters that influence waste generation and disposal. We explore this accounting system under hypothetical future waste and resource management scenarios, illustrating the utility of the model. A sensitivity analysis confirms that imports, domestic extraction and their associated hidden flows impact mostly on waste generation. The model offers enhanced utility for policy and decision makers with regard to economic mass balance and strategic waste flows, and may promote further discussion about waste technology choice in the context of reducing carbon budgets.

Safer arterial access

Intra-arterial injection of drugs intended for intravenous delivery is a frequent and potentially devastating consequence of placing an arterial line in a patient. A system is described here that prevents this complication from occurring and its use is advocated in intensive care and operating theatre settings.

Preventing iatrogenic air embolism in the intensive care unit

Air embolism is a potentially fatal consequence of incorrect connection of endotracheal tube cuff inflator devices. Currently, air lines from these devices can be connected to indwelling cannulae without impediment. This possibility can be eliminated with a simple modification of the air line, as described here.

Relapses and subsequent worsening of disability in relapsing-remitting multiple sclerosis

OBJECTIVE

To investigate whether relapses contribute to the development of subsequent sustained increase of impairment and disability in patients with multiple sclerosis (MS).

METHODS

In a random sampled subset of 256 relapsing-remitting MS (RRMS) patients from the placebo arms of 20 randomized, controlled clinical trials contained in the Sylvia Lawry Centre for MS Research (SLCMSR) open database (mean follow-up time 2.66 years), the authors tested whether time to an increase of the Expanded Disability Status Scale (EDSS) score (confirmed after 6 months) was related to the occurrence of prior relapses. In the primary analysis, EDSS progressions starting within the period used to calculate the on-study relapse rate (sacrifice period) were not counted. The result obtained was then validated in an independent validation part of the SLCMSR database (n = 320).

RESULTS

Although in the first subset of 256 RRMS patients, occurrence of relapses in the first 4 months on study appeared to be the best predictor for a shorter time to subsequent sustained increase in the EDSS score (hazard ratio [HR] 2.26 [95% CI: 1.36 to 3.75]), this finding was not confirmed in the validation dataset (HR 1.35, one-sided Wald test, lower limit of the 95% CI: 0.90).

CONCLUSION

Although relapses may result into permanent damage and Expanded Disability Status Scale (EDSS) progression, there is no consistent effect of on-study relapses on the subsequent development of sustained EDSS score increase during a typical clinical study observation period.

Inflation of a pressure-limited cuff inside a model trachea

A theory of the elastic behaviour of thin rubber films is developed to describe inflation of pressure-limited tracheal tube cuffs (a) outside and (b) inside rigid cylindrical model tracheas. At each stage, assumptions and results were successfully checked against experiment. The theory predicts cylinder wall versus intracuff pressure. This allows, for any suitable cuff (of which there are many), the determination of a single intracuff pressure that ensures a satisfactory seal, for any diameter within the human adult range, the wall pressure staying below some chosen safety limit.

The incidence and immediate respiratory consequences of pulmonary aspiration of enteral feed as detected using a modified glucose oxidase test

Pulmonary micro-aspiration of enteral feed in intubated critically ill patients has been reported to occur commonly. In this prospective observational study the incidence of micro-aspiration, diagnosed by a modified glucose oxidase test, is reported in 25 enterally fed critically ill and tracheally intubated patients on a general intensive care unit. Episodes of microaspiration were correlated with changes in PaO2/FiO2 ratio as an index of changes in degree of lung injury. The modified glucose oxidase test differs from the traditional glucose oxidase test because of the enrichment of the feed with glucose (10 g glucose added to 500 ml enteral feed resulting in a tenfold increase in glucose concentration). Pulmonary aspiration of feed was detected by exposing a glucose oxidase strip to tracheal secretions. The feed was enriched with glucose to improve the ability of the reagent strip to detect the feed. The incidence of aspiration of feed was 44% with a prevalence of 6.9% per day of intubation. Only 43% of these episodes of aspiration were detected by the feed being seen in the tracheal secretions. Aspiration was associated with a mean fall in the PaO2/FiO2 ratio of 5.6 kPa from 27.1 kPa to 21.5 kPa (P = 0.002). Aspiration of enteral feed is common and causes a demonstrable morbidity. Detection using this simple bedside test may alert the clinician to institute measures to minimize further aspiration.

Matrix effects in applying mono- and polyclonal ELISA systems to the analysis of weathered oils in contaminated soil

Commercial mono- and polyclonal enzyme-linked immunosorbent assay (ELISA) systems were applied to the on-site analysis of weathered hydrocarbon-contaminated soils at a former integrated steelworks. Comparisons were made between concentrations of solvent extractable matter (SEM) determined gravimetrically by Soxhlet (dichloromethane) extraction and those estimated immunologically by ELISA determination over a concentration range of 2000-330,000 mg SEM/kg soil dry weight. Both ELISA systems tinder-reported for the more weathered soil samples. Results suggest this is due to matrix effects in the sample rather than any inherent bias in the ELISA systems and it is concluded that, for weathered hydrocarbons typical of steelworks and coke production sites, the use of ELISA requires careful consideration as a field technique. Consideration of the target analyte relative to the composition of the hydrocarbon waste encountered appears critical.

The natural history of diabetic peripheral neuropathy determined by a 12 year prospective study using vibration perception thresholds

The development and long term progression of diabetic peripheral neuropathy was studied using vibration perception threshold (VPT) as a validated measure. Three hundred and ninety-two patients had a normal age corrected VPT (12.1 +/- 3.7 volts) at baseline, with an age corrected logarithmic VPTscore < 12. 19.9% developed an abnormal VPT over a 12 year period, increasing from 14.2 +/- 3.7 volts (VPTscore 10.4 +/- 0.6) at baseline to 35.9 +/- 9.5 volts (VPTscore 12.6 +/- 0.45) at follow up (P = 0.0001), and from 10.1 +/- 3.7volts (VPTscore 9.4 +/- 0.8) to 14.2 +/- 4.7 (VPTscore 9.8 +/- 0.8) in the rest. Over 80% thus retained a "normal" VPT after a mean diabetes duration of 16 years despite only average glycaemic control, suggesting that non-ideal long term glycaemic control leads to neuropathy in a subset of predisposed patients. VPT was correlated in 123 diabetic patients with definitive criteria for neuropathy and a range of quantitative sensory and autonomic tests. 62/63 patients with abnormal VPT fulfilled neuropathy criteria; of patients with normal VPT who fulfilled neuropathy criteria, all had at least one abnormal thermal threshold test result. We conclude that a combination of log-transformed VPT values (VPTscore > 10.1) and thermal thresholds can identify diabetic patients at risk of developing peripheral neuropathy and select patients likely to benefit from prophylaxis in clinical trials.

A spoonful of sugar--improving the sensitivity of the glucose oxidase test strip method for detecting subclinical pulmonary aspiration of enteral feed

A 74-year-old woman was admitted to the intensive care unit (ICU) with respiratory failure. Following intubation and mechanical ventilation, nasogastric enteral feeding was begun. The sensitivity of the glucose oxidase strip method for detecting aspiration of enteral feed has been questioned because the glucose levels in commonly used feeds are similar to those of normal tracheal aspirates. In order to increase the glucose concentration of the feed, 10 g of glucose was added to each 500 ml feed carton. Testing oral and tracheal secretions with standard glucose oxidase strips allowed the accurate detection of both pharyngeal regurgitation and tracheal aspiration. An episode of subclinical aspiration was detected and this was associated with a fall in the PaO2/FiO2 ratio. There were no further episodes of aspiration following the introduction of a gastric motility agent, maintaining the patient in the semi-recumbent position and an increase in the positive end expiratory pressure (PEEP).

Gel lubrication of the tracheal tube cuff reduces pulmonary aspiration

BACKGROUND

Leakage of fluid occurs along the longitudinal folds within the wall of an inflated high-volume, low-pressure cuff. Theoretically, lubrication of the cuff with a water-soluble gel might prevent aspiration by plugging the channels in the cuff wall. Pulmonary aspiration during anesthesia has been linked with postoperative pneumonia and during critical illness causes ventilator-associated pneumonia.

METHODS

Lubricated cuffs were compared with nonlubricated cuffs for leakage of dye placed in the subglottic space to the tracheobronchial tree in a benchtop model (n = 5) and in a prospective double-blinded randomized controlled trial of anesthetized patients (n = 36). The duration of the efficacy of the lubricant was determined in a prospective open observational study of critically ill patients with tracheostomies (n = 9). Dye was detected clinically by dye coloration of secretions during tracheal suctioning.

RESULTS

In the benchtop model the incidence of leakage was 0% in the lubrication group and 100% in the nonlubrication group (P < 0.01). Dye leakage in anesthetized patients was 11% in the lubrication group and 83% in the nonlubrication group (P < 0.0001). In the critically ill patients with lubricated cuffed tracheostomy tubes, leakage first occurred after a median period of 48 h (range, 24-120 h).

CONCLUSIONS

Cuff lubrication with a water-soluble gel reduces pulmonary aspiration in anesthetized patients. In the critically ill patient with a tracheostomy the protective effect is lost after 24-120 h.

Identification of cytochrome P-450 isoforms responsible for cis-tramadol metabolism in human liver microsomes

The metabolism of cis-tramadol has been studied in human liver microsomes and in cDNA-expressed human cytochrome P-450 (CYP) isoforms. Human liver microsomes catalyzed the NADPH-dependent metabolism of tramadol to the two primary tramadol metabolites, namely, O-desmethyl-tramadol (metabolite M1) and N-desmethyl-tramadol (metabolite M2). In addition, tramadol was also metabolized to two minor secondary metabolites (each comprising < or =3.0% of total tramadol metabolism), namely, N,N-didesmethyl-tramadol (metabolite M3) and N,O-didesmethyl-tramadol (metabolite M5). Kinetic analysis revealed that multiple CYP enzymes were involved in the metabolism of tramadol to both M1 and M2. For the high-affinity enzymes involved in M1 and M2 formation, K(m) values were 116 and 1021 microM, respectively. Subsequent reaction phenotyping studies were performed with a tramadol substrate concentration of 250 microM. In studies with characterized human liver microsomal preparations, good correlations were observed between tramadol metabolism to M1 and M2 and enzymatic markers of CYP2D6 and CYP2B6, respectively. Tramadol was metabolized to M1 by cDNA-expressed CYP2D6 and to M2 by CYP2B6 and CYP3A4. Tramadol metabolism in human liver microsomes to M1 and M2 was markedly inhibited by the CYP2D6 inhibitor quinidine and the CYP3A4 inhibitor troleandomycin, respectively. In summary, this study demonstrates that cis-tramadol can be metabolized to tramadol metabolites M1, M2, M3, and M5 in human liver microsomal preparations. By kinetic analysis and the results of the reaction phenotyping studies, tramadol metabolism in human liver is catalyzed by multiple CYP isoforms. Hepatic CYP2D6 appears to be primarily responsible for M1 formation, whereas M2 formation is catalyzed by CYP2B6 and CYP3A4.

Nuclear gems and Cajal (coiled) bodies in fetal tissues: nucleolar distribution of the spinal muscular atrophy protein, SMN

SMN, the affected protein in spinal muscular atrophy (SMA), is a cytoplasmic protein that also occurs in nuclear structures called "gems" and is involved in snRNP maturation. Coilin-p80 is a marker protein for nuclear Cajal bodies (coiled bodies; CBs) which are also involved in snRNP maturation, storage or transport. We now show that gems and CBs are present in all fetal tissues, even those that lack gems/CBs in the adult. Most gems and CBs occur as separate nuclear structures in fetal tissues, but their colocalization increases with fetal age and is almost complete in the adult. In adult tissues, up to half of all gems/CBs are inside the nucleolus, whereas in cultured cells they are almost exclusively nucleoplasmic. The nucleolar SMN is often more diffusely distributed, compared with nucleoplasmic gems. Up to 30% of cells in fetal tissues have SMN distributed throughout the nucleolus, instead of forming gems in the nucleoplasm. The results suggest a function for gems distinct from Cajal bodies in fetal nuclei and a nucleolar function for SMN. Spinal cord, the affected tissue in SMA, behaves differently in several respects. In both fetal and adult motor neurons, many gems/CBs occur as larger bodies closely associated with the nucleolar perimeter. Uniquely in motor neurons, gems/CBs are more numerous in adult than in fetal stages and colocalization of gems and CBs occurs earlier in development. These unusual features of motor neurons may relate to their special sensitivity to reduced SMN levels in SMA patients.

The prevention of pulmonary aspiration with control of tracheal wall pressure using a silicone cuff

A prospective open randomized controlled study was performed to assess the ability of Euromedical ILM endotracheal tube cuff (silicone cuff) to prevent pulmonary aspiration. The inflation characteristics of this silicone cuff enables the control of tracheal wall pressure. The silicone cuffed tube was shortened and an adjustable flange was used to convert it to a cuffed tracheostomy tube. Twelve patients requiring a tracheostomy on a four-bed intensive care unit (ICU) in a district general hospital received either a silicone or a Shiley cuffed tracheostomy tube. Tracheal wall pressures of both cuffs were maintained at 30 cm H2O with a constant pressure inflation device. Blue food dye was instilled once daily into the subglottic space through a fine catheter above the cuff. There were six patients in the Shiley group and six patients in the silicone cuff group. Dye leaked to the trachea in six (100%) of the Shiley group compared with none (0%) of the silicone cuff group (P = 0.001). This study confirms the effectiveness of this silicone cuff at preventing aspiration and the high incidence of leakage with the conventional high-volume low-pressure tracheostomy tube cuff.

The exon 2b region of the spinal muscular atrophy protein, SMN, is involved in self-association and SIP1 binding

Spinal muscular atrophy (SMA) is caused by mutations in the SMN (survival of motor neurons) gene and there is a correlation between disease severity and levels of functional SMN protein. Studies of structure-function relationships in SMN protein may lead to a better understanding of SMA pathogenesis. Self-association of the spinal muscular atrophy protein, SMN, is important for its function in RNA splicing. Biomolecular interaction analysis core analysis now shows that SMN self-association occurs via SMN regions encoded by exons 2b and 6, that exon 2b encodes a binding site for SMN-interacting protein-1 and that interaction occurs between exon 2- and 4-encoded regions within the SMN monomer. The presence of two separate self-association sites suggests a novel mechanism by which linear oligomers or closed rings might be formed from SMN monomers.

The relationship between SMN, the spinal muscular atrophy protein, and nuclear coiled bodies in differentiated tissues and cultured cells

The spinal muscular atrophy protein, SMN, is a cytoplasmic protein that is also found in distinct nuclear structures called "gems." Gems are closely associated with nuclear coiled bodies and both may have a direct role in snRNP maturation and pre-RNA splicing. There has been some controversy over whether gems and coiled bodies colocalize or form adjacent/independent structures in HeLa and other cultured cells. Using a new panel of antibodies against SMN and antibodies against coilin-p80, a systematic and quantitative study of adult differentiated tissues has shown that gems always colocalize with coiled bodies. In some tissues, a small proportion of coiled bodies (<10%) had no SMN, but independent or adjacent gems were not found. The most striking observation, however, was that many cell types appear to have neither gems nor coiled bodies (e.g., cardiac and smooth muscle, blood vessels, stomach, and spleen) and this expression pattern is conserved across human, rabbit, and pig species. This shows that assembly of distinct nuclear bodies is not essential for RNA splicing and supports the view that they may be storage sites for reserves of essential proteins and snRNPs. Overexpression of SMN in COS-7 cells produced supernumerary nuclear bodies, most of which also contained coilin-p80, confirming the close relationship between gems and coiled bodies. However, when SMN is reduced to very low levels in type I SMA fibroblasts, coiled bodies are still formed. Overall, the data suggest that gem/coiled body formation is not determined by high cytoplasmic SMN concentrations or high metabolic activity alone and that a differentiation-specific factor may control their formation.

Showing neuropathy is related to increased mortality in diabetic patients - a survival analysis using an accelerated failure time model

Diabetic subjects still have a reduced life expectancy despite many potential advances in patient care. Furthermore, population-based studies in well-defined cohorts of patients, to investigate the reduced life expectancies, are generally lacking. Computerized baseline data on a cohort of diabetic patients first attending our clinic during 1982-1985 were used to identify risk factors for increased mortality. This was carried out using an accelerated failure time (ACF) model. Out of 794 patients entered into the model, 201 (25.3%) patients died between 1982 and 1995. Baseline microvascular diabetic complications (peripheral sensory neuropathy and nephropathy) were found to be associated with increased mortality in patients, indicating that these are important, often overlooked, markers for those at greatest risk. Patients with type I (insulin dependent) diabetes mellitus were also identified as being at greater risk.

Population-based and opportunistic screening and eradication of Helicobacter pylori. An analysis using trial baseline data. Leeds H. pylori Study Group

OBJECTIVES

To examine whether screening and eradication of Helicobacter pylori by population-based invitation or opportunistic screening by general practitioners reduces costs to the National Health Service (NHS) of treating dyspepsia.

METHODS

A limited dependent, variable, two-step regression analysis was used to explore the baseline annual health care costs of dyspepsia for men and women aged 40-49 enrolled in the Leeds H. pylori screening and eradication trial.

RESULTS

Epidemiological and clinical questionnaires, general practitioner notes, and 13C urea breath test results were available for 4,754 individuals. After adjusting for covariates H. pylori was associated with a 6.7% increased probability of incurring gastrointestinal-related NHS costs (p < .0001) in the population aged 40-49. Additionally, H pylori increased average costs in those who seek medical care (p = .001). In consequence, H. pylori is associated with an average increased cost to the NHS of 0.30 Pound per year (95% CI: 0.17 Pound to 0.45 Pound) per adult aged 40-49. In those consulting for dyspepsia, the increased cost to the NHS was 1.04 Pounds per year (95% CI: 0.42 Pound to 1.75 Pounds) per patient. The cost of population screening and treatment would not be recovered in reduced dyspepsia costs in the lifetime of those screened. Assuming laboratory-based serology screening is used opportunistically in patients presenting with dyspepsia, it is estimated that costs would be recouped in 18 years.

CONCLUSIONS

This observational data set suggests that the costs of screening and treatment in all individuals aged 40-49 or in those presenting in primary care with dyspeptic symptoms are unlikely to be attractive on the basis of cost savings alone.

Ventilator-associated pneumonia. Diagnosis, pathogenesis and prevention

Ventilator-associated pneumonia is common, difficult to diagnose, affects the most vulnerable of patients and carries a high mortality. During prolonged mechanical ventilation the oropharynx, sinuses, dentition and stomach of critically ill patients become colonised with pathogenic bacteria. Colonised secretions pool in the oropharynx and subglottic space. These secretions repeatedly gain access to the lower airways by leakage past the tracheal tube cuff. If host defence mechanisms are overwhelmed, multiplication occurs in the lower respiratory tract producing an inflammatory response in the bronchioles and alveoli. The inflammatory response is characterised by capillary congestion, leucocyte and macrophage infiltration and fibrinous exudation into the alveolar spaces. If this inflammatory response occurs more than 48 h after intubation, it is called ventilator-associated pneumonia. Prevention depends on reducing upper airway and gastrointestinal reservoirs of bacteria, reducing or abolishing aspiration of these bacteria past the tracheal tube cuff and enhancing bacterial clearance from the lower airways.

Improving the shape and compliance characteristics of a high-volume, low-pressure cuff improves tracheal seal

A prototype design of a compliant latex, high-volume, low-pressure cuffed tracheal tube cuff (CHVLP) was compared with the Mallinckrodt Hi-Lo, Sheridan preformed and Portex Profile high-volume, low-pressure (HVLP) cuffed tracheal tubes for leakage of dye placed above the cuff in a benchtop mechanical ventilation model and in five isolated pig tracheas. There was no leakage in the ventilation model or in the pig tracheas with the prototype CHVLP. There was rapid leakage in the ventilation model and in all the pig tracheas for the Mallinckrodt Hi-Lo, the Sheridan preformed and the Portex Profile cuffs. This benchtop study suggests that improved HVLP cuff compliance characteristics may be beneficial in the prevention of leakage of fluid to the lungs known to occur with HVLP cuffs.

Renal nerve and alpha 2-adrenergic action during acute volume expansion in the anaesthetized rat

1. The effects of renal denervation and alpha 2-adrenoceptor blockade on diuresis and natriuresis in response to acute volume expansion (VE) were investigated in anaesthetized rats. 2. In normal rats, a 30 min intravascular VE of up to 7.5% of bodyweight caused a significant diuresis and natriuresis. 3. Denervation enhanced the diuretic effect of VE by 39%, while alpha 2 blockade by 12 mumol/kg per h rauwolscine significantly inhibited the response by 61% in innervated kidneys and 43% in denervated kidneys. 4. Similar results were found for natriuresis in both innervated and denervated kidneys. 5. The results demonstrate that renal sympathetic nerve activity inhibits part of the increase in sodium and water excretion caused by VE, since denervation increased excretion under these conditions. The contribution of renal nerves to the control of renal function, however, decreases during the response to VE. 6. alpha 2-Adrenoceptor action enhanced the diuretic and natriuretic effects of VE by mechanisms otherwise unrelated to renal nerve activity.

The analysis of a bivariate multi-state Markov transition model for rheumatoid arthritis with an incomplete disease history

In many long-term chronic diseases, patients pass through an observable sequence of ordered clinical states as their condition progressively worsens. Often the information on which disease state the patient is in is incompletely recorded, usually with information only available on the occasion of a clinic visit. This article describes a novel analysis of data from a clinical trial, in which several such outcome measures of disease state have been recorded simultaneously. The article is motivated by the analysis of a multi-centre double-blind placebo-controlled clinical study into the effect of continual low dose corticosteroid treatment on the progression of X-ray scores for patients with rheumatoid arthritis. Previous methods of analysis of such data have been based on an independence analysis, thus ignoring any correlation that may exist between the outcomes. This article shows that such an approach can lead to biased underestimates of the covariate effects if an independence model is used. Biased estimates of the covariate effects were found when the model was fitted to the trial data. The bivariate model was also shown to provide a significantly better fit to the data. However, the bivariate model did prove more difficult to fit, and both models demonstrated a highly significant treatment effect with comparable clinical effect.

Prevention of tracheal aspiration using the pressure-limited tracheal tube cuff

A new design of tracheal tube cuff, the pressure-limited cuff, used with a constant-pressure inflation system, was compared with a high-volume low-pressure cuffed tracheal tube for leakage of dye placed in the subglottic space into the trachea. Patients requiring ventilation on the intensive care unit were randomly allocated into two groups, one for each type of cuff, and blue food dye was instilled daily via a fine catheter above the cuff into the subglottic space. There were eight patients in the high-volume low-pressure group and seven in the pressure-limited cuff group. Dye leaked into the trachea in seven (87%) of the high-volume low-pressure group compared with none (0%) of the pressure-limited cuff group (p < 0.01). This study demonstrates that the pressure-limited cuffed tracheal tube, in combination with a constant-pressure inflation device, prevents leakage of fluid into the lungs that occurs with high-volume low-pressure cuffs in the critically ill, intubated patient.

Compliance characteristics of the Portex Soft Seal Cuff improves seal against leakage of fluid in a pig trachea model

BACKGROUND

The Portex Soft Seal high-volume, low-pressure cuffed tracheal tube was compared with the Mallinckrodt HiLo, Sheridan Preformed and Portex Profile tracheal tubes for leakage of dye placed in the subglottic space of a pig's trachea which was used in a benchtop mechanical ventilation model and in six isolated pig tracheas.

RESULTS

There was no leakage, either in the ventilation model or in the isolated tracheas in the Portex Soft Seal group. There was rapid leakage in the ventilation model and in all the isolated tracheas for the Mallinckrodt HiLo, and five out of six isolated tracheas for the Sheridan Preformed and the Portex Profile group.

CONCLUSIONS

This benchtop study suggests that the improved compliance characteristics of the Portex Soft Seal cuff are beneficial in preventing leakage of fluid in these models.

Outcome on diabetic foot complications in relation to clinical examination and quantitative sensory testing: a case-control study

A total of 405 diabetic patients who first attended St Thomas' Diabetes Clinic between 1982 and 1985 had a detailed standardized computerized first visit record, including a structured foot examination and toe vibration perception thresholds (VPT, Biothesiometer), were reviewed in 1995. None of the patients had a history of foot ulceration at first visit. Twenty-five patients (6.2%) developed foot ulcers (n = 11, 2.7%) or had an amputation (n = 14, 3.5%) over a mean 12-year period. Twenty of these patients were then individually matched with 3 non-ulcer patients. Statistically significant odds ratios (OR) were found for a baseline abnormal age-adjusted toe VPT (OR 4.38, CI 1.11-17.26; p = 0.01); abnormal clinical examination (at least 1 abnormality out of: ankle jerks, tuning fork or cotton wool sensation; OR 2.3, CI 1.00-5.20; p < 0.01); and HbA1 (OR 1.30, CI 1.01-1.66; P < 0.02) in patients who subsequently developed lower extremity complications. The sensitivity of VPT (70%) was better than that for clinical testing (55 %) in predicting long-term complications, although all tests showed similar specificity (70-72%). The risk of events also doubled for every 10 years of diabetes (OR 2.10, CI 1.11-4.30; p = 0.02). We conclude that age-corrected VPT measurements, which are objective and simple to perform, are better predictors of future foot complications than semi-quantitative tests in diabetes clinics. We encourage their use in the campaign to reduce the morbidity of diabetic peripheral neuropathy.

Evaluation of a new design of tracheal tube cuff to prevent leakage of fluid to the lungs

A new design of tracheal tube cuff was compared with two types of high-volume, low-pressure (HVLP) cuffed tracheal tube for leakage of fluid from the subglottic space into the trachea. Spontaneous and positive-pressure ventilation were simulated using a mechanical lung, an intubated model trachea and a ventilator. Excised human tracheas were intubated and leakage past the cuff assessed. Distention of the tracheal wall was measured. HVLP cuffs leaked rapidly in the model during all modes of ventilation, and also in the excised human tracheas. This leakage occurred preferentially down longitudinal folds that occur in the HVLP cuff wall. The new design completely prevented leakage in the model during all modes of ventilation, during tracheal suctioning, and with tube movement. The new cuff also prevented leakage in the excised human tracheas. Tracheal wall distention and tracheal wall pressures were similar for all cuffs tested.

Leakage of fluid past the tracheal tube cuff in a benchtop model

We have assessed a range of high volume, low pressure (HVLP) cuffed tracheal tubes in a benchtop model, for leakage of fluid from above the cuff to the model trachea below, during various ventilatory modes. Rapid leakage occurred in the model during all modes of ventilation, unless tracheal pressure was greater than the height of fluid in the column above the cuff. This leakage occurred preferentially down longitudinal folds that occur in the HVLP cuff wall. This model suggests that, if a longitudinal fold within the cuff wall is patent, then the possibility exists of subglottic to tracheal leakage.

The growth of new dental practices established in the North West of England and North Wales between 1985 and 1990

This study examined the growth of 52 new dental practices established between 1985 and 1990 in the North West of England and North Wales. Growth was measured from the number of estimates (equivalent to a course of treatment) submitted by the practice to the Dental Practice Board since the practice first opened. Values ranged from less than 1000 estimates up to 12,000 estimates during the first 24 months; the modal value was between 2000 and 2999. The number of estimates was not associated with the resident population to dentist ratio for the surrounding locality.