ORCID Profile
0000-0002-0991-6213
Current Organisations
The University of Edinburgh
,
Oxford University Hospitals NHS Foundation Trust
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 25-04-2008
DOI: 10.1002/RCM.3572
Abstract: The aim of this paper is to review the factors which may affect breath (13)CO(2)/(12)CO(2) natural abundance in patients undergoing surgery or intensive care. Intravenous glucose administration is a major determinant of the (13)CO(2)/(12)CO(2) of breath as intravenous glucose preparations are almost all derived from cornstarch. In addition, the oxidation of endogenous substrates can affect the (13)CO(2)/(12)CO(2) ratio. During many endoscopic procedures, such as laparoscopic surgery, carbon dioxide insufflation is used to provide a working space. As medical CO(2) is relatively depleted in (13)CO(2) compared with endogenous and exogenous metabolic CO(2) sources, breath (13)CO(2)/(12)CO(2) measurements can be used to estimate CO(2) absorption during these procedures. However, all these factors may also be affected by the bicarbonate pool, making a definitive attribution of changes in breath (13)CO(2)/(12)CO(2) to a single factor problematic.
Publisher: IOP Publishing
Date: 27-11-2009
DOI: 10.1088/1752-7155/3/4/047005
Abstract: Carbon dioxide (CO(2)) is the gas most commonly used to inflate the body cavities during 'keyhole' surgery (e.g. laparoscopy and thoracoscopy). However, CO(2) can be absorbed, leading to increased arterial CO(2) and increased CO(2) elimination from the lungs. These increases in CO(2) are observed following a wide variety of procedures both in adults and in infants and children. Although it is usually assumed that increases in arterial or end-tidal CO(2) directly reflect absorption of CO(2) from body cavities, this is not necessarily true, as either increases in metabolically produced CO(2) or respiratory compromise making it more difficult to eliminate CO(2) could also be responsible for these changes. Recently, a new technique has been introduced which enables absorbed CO(2) to be distinguished from metabolic CO(2).
Publisher: BMJ
Date: 10-04-2013
Publisher: BMJ
Date: 14-02-2014
Publisher: Wiley
Date: 09-03-2021
DOI: 10.1111/ANAE.15458
Abstract: Peri‐operative SARS‐CoV‐2 infection increases postoperative mortality. The aim of this study was to determine the optimal duration of planned delay before surgery in patients who have had SARS‐CoV‐2 infection. This international, multicentre, prospective cohort study included patients undergoing elective or emergency surgery during October 2020. Surgical patients with pre‐operative SARS‐CoV‐2 infection were compared with those without previous SARS‐CoV‐2 infection. The primary outcome measure was 30‐day postoperative mortality. Logistic regression models were used to calculate adjusted 30‐day mortality rates stratified by time from diagnosis of SARS‐CoV‐2 infection to surgery. Among 140,231 patients (116 countries), 3127 patients (2.2%) had a pre‐operative SARS‐CoV‐2 diagnosis. Adjusted 30‐day mortality in patients without SARS‐CoV‐2 infection was 1.5% (95%CI 1.4–1.5). In patients with a pre‐operative SARS‐CoV‐2 diagnosis, mortality was increased in patients having surgery within 0–2 weeks, 3–4 weeks and 5–6 weeks of the diagnosis (odds ratio (95%CI) 4.1 (3.3–4.8), 3.9 (2.6–5.1) and 3.6 (2.0–5.2), respectively). Surgery performed ≥ 7 weeks after SARS‐CoV‐2 diagnosis was associated with a similar mortality risk to baseline (odds ratio (95%CI) 1.5 (0.9–2.1)). After a ≥ 7 week delay in undertaking surgery following SARS‐CoV‐2 infection, patients with ongoing symptoms had a higher mortality than patients whose symptoms had resolved or who had been asymptomatic (6.0% (95%CI 3.2–8.7) vs. 2.4% (95%CI 1.4–3.4) vs. 1.3% (95%CI 0.6–2.0), respectively). Where possible, surgery should be delayed for at least 7 weeks following SARS‐CoV‐2 infection. Patients with ongoing symptoms ≥ 7 weeks from diagnosis may benefit from further delay.
Publisher: Springer Science and Business Media LLC
Date: 08-01-2019
Publisher: Springer Science and Business Media LLC
Date: 06-02-2019
Publisher: Wiley
Date: 24-08-2021
DOI: 10.1111/ANAE.15563
Abstract: SARS‐CoV‐2 has been associated with an increased rate of venous thromboembolism in critically ill patients. Since surgical patients are already at higher risk of venous thromboembolism than general populations, this study aimed to determine if patients with peri‐operative or prior SARS‐CoV‐2 were at further increased risk of venous thromboembolism. We conducted a planned sub‐study and analysis from an international, multicentre, prospective cohort study of elective and emergency patients undergoing surgery during October 2020. Patients from all surgical specialties were included. The primary outcome measure was venous thromboembolism (pulmonary embolism or deep vein thrombosis) within 30 days of surgery. SARS‐CoV‐2 diagnosis was defined as peri‐operative (7 days before to 30 days after surgery) recent (1–6 weeks before surgery) previous (≥7 weeks before surgery) or none. Information on prophylaxis regimens or pre‐operative anti‐coagulation for baseline comorbidities was not available. Postoperative venous thromboembolism rate was 0.5% (666/123,591) in patients without SARS‐CoV‐2 2.2% (50/2317) in patients with peri‐operative SARS‐CoV‐2 1.6% (15/953) in patients with recent SARS‐CoV‐2 and 1.0% (11/1148) in patients with previous SARS‐CoV‐2. After adjustment for confounding factors, patients with peri‐operative (adjusted odds ratio 1.5 (95%CI 1.1–2.0)) and recent SARS‐CoV‐2 (1.9 (95%CI 1.2–3.3)) remained at higher risk of venous thromboembolism, with a borderline finding in previous SARS‐CoV‐2 (1.7 (95%CI 0.9–3.0)). Overall, venous thromboembolism was independently associated with 30‐day mortality (5.4 (95%CI 4.3–6.7)). In patients with SARS‐CoV‐2, mortality without venous thromboembolism was 7.4% (319/4342) and with venous thromboembolism was 40.8% (31/76). Patients undergoing surgery with peri‐operative or recent SARS‐CoV‐2 appear to be at increased risk of postoperative venous thromboembolism compared with patients with no history of SARS‐CoV‐2 infection. Optimal venous thromboembolism prophylaxis and treatment are unknown in this cohort of patients, and these data should be interpreted accordingly.
Publisher: MDPI AG
Date: 30-09-2020
Abstract: Survivors of childhood cancer are at risk for long-term treatment-induced health sequelae, including gonadotoxicity and iatrogenic infertility. At present, for prepubertal boys there are no viable clinical options to preserve future reproductive potential. We investigated the effect of a pubertal induction regimen with gonadotrophins on prepubertal human testis xenograft development. Human testis tissue was obtained from patients with cancer and non-malignant haematological disorders (n = 6 aged 1–14 years) who underwent testis tissue cryopreservation for fertility preservation. Fresh and frozen-thawed testis fragments were transplanted subcutaneously or intratesticularly into immunocompromised mice. Graft-bearing mice received injections of vehicle or exogenous gonadotrophins, human chorionic gonadotrophin (hCG, 20 IU), and follicle-stimulating hormone (FSH, 12.5 IU) three times a week for 12 weeks. The gross morphology of vehicle and gonadotrophin-exposed grafts was similar for both transplantation sites. Exposure of prepubertal human testis tissue xenografts to exogenous gonadotrophins resulted in limited endocrine function of grafts, as demonstrated by the occasional expression of the steroidogenic cholesterol side-chain cleavage enzyme (CYP11A1). Plasma testosterone concentrations (0.13 vs. 0.25 ng/mL p = 0.594) and seminal vesicle weights (10.02 vs. 13.93 mg p = 0.431) in gonadotrophin-exposed recipient mice were comparable to vehicle-exposed controls. Regardless of the transplantation site and treatment, initiation and maintenance of androgen receptor (AR) expression were observed in Sertoli cells, indicating commitment towards a more differentiated status. However, neither exogenous gonadotrophins (in castrated host mice) nor endogenous testosterone (in intact host mice) were sufficient to repress the expression of markers associated with immature Sertoli cells, such as anti-Müllerian hormone (AMH) and Ki67, or to induce the redistribution of junctional proteins (connexin 43, CX43 claudin 11, CLDN11) to areas adjacent to the basement membrane. Spermatogonia did not progress developmentally but remained the most advanced germ cell type in testis xenografts. Overall, these findings demonstrate that exogenous gonadotrophins promote partial activation and maturation of the somatic environment in prepubertal testis xenografts. However, alternative hormone regimens or additional factors for pubertal induction are required to complete the functional maturation of the spermatogonial stem cell (SSC) niche.
Publisher: Oxford University Press (OUP)
Date: 24-03-2021
DOI: 10.1093/BJS/ZNAB101
Abstract: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18–49, 50–69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351 best case 196, worst case 816) or non-cancer surgery (733 best case 407, worst case 1664). Both exceeded the NNV in the general population (1840 best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population.
Publisher: Wiley
Date: 09-08-2021
DOI: 10.1111/ANAE.15560
Abstract: We aimed to determine the impact of pre‐operative isolation on postoperative pulmonary complications after elective surgery during the global SARS‐CoV‐2 pandemic. We performed an international prospective cohort study including patients undergoing elective surgery in October 2020. Isolation was defined as the period before surgery during which patients did not leave their house or receive visitors from outside their household. The primary outcome was postoperative pulmonary complications, adjusted in multivariable models for measured confounders. Pre‐defined sub‐group analyses were performed for the primary outcome. A total of 96,454 patients from 114 countries were included and overall, 26,948 (27.9%) patients isolated before surgery. Postoperative pulmonary complications were recorded in 1947 (2.0%) patients of which 227 (11.7%) were associated with SARS‐CoV‐2 infection. Patients who isolated pre‐operatively were older, had more respiratory comorbidities and were more commonly from areas of high SARS‐CoV‐2 incidence and high‐income countries. Although the overall rates of postoperative pulmonary complications were similar in those that isolated and those that did not (2.1% vs 2.0%, respectively), isolation was associated with higher rates of postoperative pulmonary complications after adjustment (adjusted OR 1.20, 95%CI 1.05–1.36, p = 0.005). Sensitivity analyses revealed no further differences when patients were categorised by: pre‐operative testing use of COVID‐19‐free pathways or community SARS‐CoV‐2 prevalence. The rate of postoperative pulmonary complications increased with periods of isolation longer than 3 days, with an OR (95%CI) at 4–7 days or ≥ 8 days of 1.25 (1.04–1.48), p = 0.015 and 1.31 (1.11–1.55), p = 0.001, respectively. Isolation before elective surgery might be associated with a small but clinically important increased risk of postoperative pulmonary complications. Longer periods of isolation showed no reduction in the risk of postoperative pulmonary complications. These findings have significant implications for global provision of elective surgical care.
Publisher: BMJ
Date: 03-2020
DOI: 10.1136/BMJOPEN-2019-034253
Abstract: The optimal size of the health workforce for children’s surgical care around the world remains poorly defined. The goal of this study was to characterise the surgical workforce for children across Brazil, and to identify associations between the surgical workforce and measures of childhood health. This study is an ecological, cross-sectional analysis using data from the Brazil public health system ( Sistema Único de Saúde ). We collected data on the surgical workforce (paediatric surgeons, general surgeons, anaesthesiologists and nursing staff), perioperative mortality rate (POMR) and under-5 mortality rate (U5MR) across Brazil for 2015. We performed descriptive analyses, and identified associations between the workforce and U5MR using geospatial analysis (Getis-Ord-Gi analysis, spatial cluster analysis and linear regression models). There were 39 926 general surgeons, 856 paediatric surgeons, 13 243 anaesthesiologists and 103 793 nurses across Brazil in 2015. The U5MR ranged from 11 to 26 deaths/1000 live births and the POMR ranged from 0.11–0.17 deaths/100 000 children across the country. The surgical workforce is inequitably distributed across the country, with the wealthier South and Southeast regions having a higher workforce density as well as lower U5MR than the poorer North and Northeast regions. Using linear regression, we found an inverse relationship between the surgical workforce density and U5MR. An U5MR of 15 deaths/1000 births across Brazil is associated with a workforce level of 5 paediatric surgeons, 200 surgeons, 100 anaesthesiologists or 700 nurses/100 000 children. We found wide disparities in the surgical workforce and childhood mortality across Brazil, with both directly related to socioeconomic status. Areas of increased surgical workforce are associated with lower U5MR. Strategic investment in the surgical workforce may be required to attain optimal health outcomes for children in Brazil, particularly in rural regions.
Location: United Kingdom of Great Britain and Northern Ireland
Location: Trinidad and Tobago
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Merrill McHoney.