Analysis of oxygen saturation levels recorded during dental intravenous sedations - a retrospective quality assurance of 3500 cases

ABSTRACT Background: The death of a patient under dental intravenous sedation in New South Wales, Australia, in 2002 while being treated by a dentist with appropriate training in intravenous conscious sedation (ICS), (Graduate Diploma in Clinical Dentistry; Conscious Sedation and Pain Control, University of Sydney) has once again brought into question the safety of ICS. The cause of death was irreversible cerebral hypoxia following a cardiac arrest, which was precipitated by numerous periods of ever-deepening hypoxaemia. Aim: This retrospective, quality-assurance audit investigated whether safe oxygen saturation levels could be maintained during single operator/sedationist dental sedations, when operating within the joint Royal Australasian College of Dental Surgeons (RACDS) and Australian and New Zealand College of Anaesthetists (ANZCA) PS21 guidelines for conscious sedation. Methodology: Safe oxygen saturation levels were defined as pulse oximeter readings of 94% and above. The recording of two or more readings of less than 94% during a sedation procedure was defined as the outcome of interest. The association of the variables of age (eighteen and over), gender, weight, the American Society of Anesthesiologists (ASA) Classification I or II and the use of propofol in addition to midazolam and fentanyl, to low saturations, was examined. Two sub-cohorts were randomly generated: 1,750 patients were sedated with iv midazolam and fentanyl and 1,750 patients received propofol, in sub-anaesthetic increments, in addition to midazolam and fentanyl. All patients received supplemental oxygen. Initial sedation was established using midazolam and fentanyl in both sub-cohorts. The second sub-cohort received sub-anaesthetic increments of propofol during times of noxious stimulation. Statistical analysis of the data used cross-tabulation of the variables by outcome, an associated chi- squared test and corresponding logistic regression analysis, together with odds ratio (OR) and a 95% confidence interval (95%CI). Results: Patient exposure to two or more oxygen de-saturations below 94% was uncommon. The null hypothesis could not be rejected because there was no significant difference between the saturation levels recorded for each sub-cohort (μ1 - μ2 = 0), where μ1 was the cohort that received propofol in addition to midazolam and fentanyl, and μ2 was the cohort that received midazolam and fentanyl only. Analysis of the two population groups found them to be quite different in make-up. Had the two population groups been similar in make-up, then μ1 - μ2 may not have equaled 0, and the outcome of the hypothesis test may have been to reject H0. The variables that were significantly associated with low saturations were age, gender and weight. The data showed that males were three times more likely than females to experience low saturations. Patients 45 years and older were nearly eight times more likely to experience low saturations than patients 25 years or younger. Patients classified as being in the gender- specific high weight group were twice as likely to experience low saturations than those in the low and medium weight groups. Neither the dose of midazolam, nor the additional use of propofol were significant risk factors, even after adjusting for the variables of age, gender and weight. ASA Classification (I or II) was not a determinant of risk. Conclusion: Within the limitations of this study, the data support that a single operator/sedationist, working within the RACDS/ANZCA document PS21 guidelines, and supported by a team of experienced dental nurses, can consistently maintain safe oxygen saturation levels when working on ASA I or II patients, regardless of age, gender, gender-specific weight, dose of midazolam, or the additional use of propofol

An analysis of non-white transport requirements in an Eastern Cape urban area

From Preface: The following research is centred around the Grahamstown non-white urban transportation problem. The bus service under consideration is owned and operated by the Grahamstown Municipality and is attached to the City Fire Department. It caters only for non-white commuters by operating fourteen buses, which carry approximately 1 200 000 people per year. As such, the difficulties encountered by this transport service should be generally, though not entirely, applicable only to relatively small non-white transport undertakings. The aims of this research are threefold: 1. to establish the environment within which transport undertakings operate, the structure of the undertaking in response to this environment and the problems which such undertakings encounter in their daily operations ; 2. by analysing in detail a specific transport service, an attempt has been made to delineate problem areas in both the cost and revenue structures, and to ascertain the degree of management awareness of the existence of these problems ; and 3. to determine the social impact of this transport operation and to evaluate all aspects of the service in relation to commuters, business and social needs and wants. Unfortunately, an attempt to extend this type of research to further Eastern Cape urban areas was unsuccessful due to the refusal by certain transport undertakings and government bodies to provide essential information

The effects of relative market share and the rate of market growth on the strategic attributes and financial performance of selected South African companies from 1977 to 1981

This thesis analyses the effects of relative market share and the rate of market growth on the strategic characteristics and financial performance of selected companies quoted on the Johannesburg Stock Exchange over the period 1977 to 198. It is well established that business performance is partially contingent upon relative market share position and the rate of market growth. Together these variables comprise the basis of the Boston Consulting Group approach to portfolio analysis in the form of the Boston Consulting Group Growth/Share Matrix. A methodology was designed to test the validity of this matrix in measuring and predicting corporate behaviour at the business level in South Africa. Selected companies were placed into the matrix and analysed in terms of their strategic attributes (represented by selected financial ratios) and their level of performance (represented by a wide range of financial performance measures). The research findings show that relative market share and the rate of market growth have a significant impact on the strategic attributes and financial performance of South African businesses. Also, certain attributes are closely associated with particular types of performance. Therefore, given a specific performance target, management should ultimately be able to isolate and monitor the relevant strategic attributes in ensuring that the target is achieved. The analysis of contingent models of strategy is still in its infancy, but this study indicates that the field is possessed of great potential

The linking of a Brånemark implant to a natural tooth

The introduction of a safe, reliable and predictable implant system for dental reconstruction by Professor Per-lngvar Branemark has seen an explosion in the number of patients receiving implant therapy to restore complete and partial edentulism. The reconstruction of partial edentulism may require the linking of the implant to a natural tooth. This study was carried out to investigate the relative mobility of the natural tooth and a Branemark implant, and to determine the feasibility of linking these two elements by means of a fixed prosthesis. The mobility of natural teeth is well documented. However, the mobility and flexibility of a Branemark osseointegrated implant is unknown. Short, medium and long implant abutments were attached to a fixture and placed under load and the deflection of the implant measured. A three-unit bridge linked to a fixture with short, medium and long abutment lengths was also examined. The results indicate that the inherent flexibility of the fixture and abutment system provides the possibility for linkage of the Branemark implant and the natural tooth

Structural reliability of existing rc beams strengthened with UHPFRC tensile layers

A methodology for reliability analysis of reinforced concrete (RC) beams strengthened with ultra high-performance fibre reinforced concrete (UHPFRC) tensile layers is presented. The proposed methodology includes stochastic stress-block analysis of a section, assuming a perfect bond between the RC beam and the UHPFRC layer. Annual reliability analysis of the RC beam before and after the strengthening operation is conducted. Deterioration induced by chloride corrosion is incorporated into the analysis via a chloride induced corrosion model based on Fick’s law of diffusion and described stochastically to account for the epistemic uncertainty in the time to corrosion initiation and rate of corrosion. A plot for determining the required thickness of the UHPFRC tensile layer to upgrade to the required reliability level is also given, considering the time from construction to when the strengthening operation is conducted. The proposed approach is easy to apply for routine practice

Risk Attitude of Monocrop and Intercrop Farmers in Kebbi State, Nigeria

The research investigated the risk attitude, of farmers in Kebbi State, Nigeria, with the aim of generating reliable information on the influence of risk attitudes of the decision-making behaviour of farmers. Agricultural production is highly characterized by risks for this reason, farmers’ attitudes towards risk is imperative in understanding their behaviour towards the adoption of new technology and managerial decisions. The technique applied in order to achieve the objectives of the study was Experimental Gambling Approach. Data to conduct the research was obtained mainly from primary sources through a questionnaire survey of 256 farmers, comprising 98 monocroppers and 158 intercroppers. The results from the study revealed that all the farmers exhibit some level of risk aversion.  The intercroppers were statistically significantly more risk-averse than the monocroppers.  Risk attitude influences the decisions farmers make in the production process and should be considered when formulating agricultural policies. Keywords: Risk attitude, monocroppers, intercroppers and experimental gambling approach.

Beyond Intuition, a Framework for Applying GPs to Real-World Data

Gaussian Processes (GPs) offer an attractive method for regression over small, structured and correlated datasets. However, their deployment is hindered by computational costs and limited guidelines on how to apply GPs beyond simple low-dimensional datasets. We propose a framework to identify the suitability of GPs to a given problem and how to set up a robust and well-specified GP model. The guidelines formalise the decisions of experienced GP practitioners, with an emphasis on kernel design and options for computational scalability. The framework is then applied to a case study of glacier elevation change yielding more accurate results at test time.Comment: Accepted at the 1st ICML Workshop on Structured Probabilistic Inference and Generative Modelling (2023

Surgical correction of a persistent right aortic arch in a kitten with concurrent mitral and tricuspid valve insufficiency and long-term post-operative management of residual megaoesophagus

A Maine Coon kitten was diagnosed with persistent right aortic arch and concurrent mitral and tricuspid valve insufficiency. Diuretic and positive inotropic treatment were administered before surgical treatment was attempted. Surgical ligation of the ligamentum arteriosum was performed successfully. Regurgitation did not resolve despite efforts to slowly introduce solid food to the diet over a period of two months. The kitten suffered from several incidences of aspiration pneumonia that responded to antibiotic treatment. Follow-up computed tomography ruled-out extraluminal constriction of the oesophagus, and oesophagoscopy confirmed a residual megaoesophagus six months post-operatively. The kitten was euthanised seven months after surgery. The importance of a complete cardiac work-up and oesophagoscopy in suspected vascular ring anomaly examinations are highlighted in this case study.https://bvajournals.onlinelibrary.wiley.com/journal/205261212022-06-09hj2022Companion Animal Clinical Studie

Cell-free (RNA) and cell-associated (DNA) HIV-1 and postnatal transmission through breastfeeding

<p>Introduction - Transmission through breastfeeding remains important for mother-to-child transmission (MTCT) in resource-limited settings. We quantify the relationship between cell-free (RNA) and cell-associated (DNA) shedding of HIV-1 virus in breastmilk and the risk of postnatal HIV-1 transmission in the first 6 months postpartum.</p> <p>Materials and Methods - Thirty-six HIV-positive mothers who transmitted HIV-1 by breastfeeding were matched to 36 non-transmitting HIV-1 infected mothers in a case-control study nested in a cohort of HIV-infected women. RNA and DNA were quantified in the same breastmilk sample taken at 6 weeks and 6 months. Cox regression analysis assessed the association between cell-free and cell-associated virus levels and risk of postnatal HIV-1 transmission.</p> <p>Results - There were higher median levels of cell-free than cell-associated HIV-1 virus (per ml) in breastmilk at 6 weeks and 6 months. Multivariably, adjusting for antenatal CD4 count and maternal plasma viral load, at 6 weeks, each 10-fold increase in cell-free or cell-associated levels (per ml) was significantly associated with HIV-1 transmission but stronger for cell-associated than cell-free levels [2.47 (95% CI 1.33–4.59) vs. aHR 1.52 (95% CI, 1.17–1.96), respectively]. At 6 months, cell-free and cell-associated levels (per ml) in breastmilk remained significantly associated with HIV-1 transmission but was stronger for cell-free than cell-associated levels [aHR 2.53 (95% CI 1.64–3.92) vs. 1.73 (95% CI 0.94–3.19), respectively].</p> <p>Conclusions - The findings suggest that cell-associated virus level (per ml) is more important for early postpartum HIV-1 transmission (at 6 weeks) than cell-free virus. As cell-associated virus levels have been consistently detected in breastmilk despite antiretroviral therapy, this highlights a potential challenge for resource-limited settings to achieve the UNAIDS goal for 2015 of eliminating vertical transmission. More studies would further knowledge on mechanisms of HIV-1 transmission and help develop more effective drugs during lactation.</p&gt