Effect of skin tone on the accuracy of the estimation of arterial oxygen saturation by pulse oximetry: a systematic review.

BACKGROUND: Pulse oximetry-derived oxygen saturation (SpO2) is an estimate of true arterial oxygen saturation (SaO2). The aim of this review was to evaluate available evidence determining the effect of skin tone on the ability of pulse oximeters to accurately estimate SaO2. METHODS: Published literature was screened to identify clinical and non-clinical studies enrolling adults and children when SpO2 was compared with a paired co-oximetry SaO2 value. We searched literature databases from their inception to March 20, 2023. Risk of bias (RoB) was assessed using the QUADAS-2 tool. Certainty of assessment was evaluated using the GRADE tool. RESULTS: Forty-four studies were selected reporting on at least 222 644 participants (6121 of whom were children) and 733 722 paired SpO2-SaO2 measurements. Methodologies included laboratory studies, prospective clinical, and retrospective clinical studies. A high RoB was detected in 64% of studies and there was considerable heterogeneity in study design, data analysis, and reporting metrics. Only 11 (25%) studies measured skin tone in 2353 (1.1%) participants; the remainder reported participant ethnicity: 68 930 (31.0%) participants were of non-White ethnicity or had non-light skin tones. The majority of studies reported overestimation of SaO2 by pulse oximetry in participants with darker skin tones or from ethnicities assumed to have darker skin tones. Several studies reported no inaccuracy related to skin tone. Meta-analysis of the data was not possible. CONCLUSIONS: Pulse oximetry can overestimate true SaO2 in people with darker skin tones. The clinical relevance of this bias remains unclear, but its magnitude is likely to be greater when SaO2 is lower. SYSTEMATIC REVIEW PROTOCOL: International Prospective Register of Systematic Reviews (PROSPERO): CRD42023390723.

Information Asymmetry in Hospitals: Evidence of the Lack of Cost Awareness in Clinicians.

BACKGROUND: Information asymmetries and the agency relationship are two defining features of the healthcare system. These market failures are often used as a rationale for government intervention. Many countries have government financing and provision of healthcare in order to correct for this, while health technology agencies also exist to improve efficiency. However, informational asymmetries and the resulting principal-agent problem still persist, and one example is the lack of cost awareness amongst clinicians. This study explores the cost awareness of clinicians across different settings. METHODS: We targeted four clinical cohorts: medical students, Senior House Officers/Interns, Mid-grade Senior Registrar/Residents, and Consultant/Attending Physicians, in six hospitals in the United Kingdom, the United States, Australia, New Zealand and Spain. The survey asked respondents to report the cost (as they recalled) of different types of scans, visits, medications and tests. Our analysis focused on the differential between the perceived/recalled cost and the actual cost. We explored variation across speciality, country and other potential confounders. Cost-awareness levels were estimated based on the cost estimates within 25% of the actual cost. RESULTS: We received 705 complete responses from six sites across five countries. Our analysis found that respondents often overestimated the cost of common tests while underestimating high-cost tests. The mean cost-awareness levels varied between 4 and 23% for different items. Respondents acknowledged that they did not feel they had received adequate training in cost awareness. DISCUSSION: The current financial climate means that cost awareness and the appropriate use of scarce healthcare resources is more paramount than perhaps ever before. Much of the focus of health economics research is on high-cost innovative technologies, yet there is considerable waste in the system with respect to overtreatment and overdiagnosis. Common reasons put forward for this include defensive medicine, poor education, clinical uncertainty and the institution of protocols. CONCLUSION: Given the role of clinicians in the healthcare system, as agents both for patients and for providers, more needs to be done to remove informational asymmetries and improve clinician cost awareness.

Thromboelastography demonstrates progressive hypercoagulability in COVID-19 patients admitted to ICU with respiratory failure.

Thromboembolic complications are associated with COVID-19 owing to the hypercoagulable nature of the disease. Although patients with COVID-19 often have higher levels of fibrinogen and D-dimers, hypercoagulability has been attributed to various other factors too. In this prospective observational study conducted between April 2020 and June 2020, we compared coagulation parameters using thromboelastography in COVID-19 patients to non-COVID-19 patients admitted to ICU with respiratory failure. This study demonstrated a significant difference between the cohorts in functional fibrinogen (CFF) progressively from third day of ICU admission whilst there was no difference in the Clauss fibrinogen levels. COVID-19 patients also demonstarted supranormal R time indicating hypocoagulability. These mixed coagulation changes suggest targeting fibrinogen or platelets may prevent thromboembolic complications in COVID-19.

Protocol for a prospective double-blind, randomised, placebo-controlled feasibility trial of octreotide infusion during liver transplantation.

INTRODUCTION: Liver transplantation is a complex operation that can provide significant improvements in quality of life and survival to the recipients. However, serious complications are common and include major haemorrhage, hypotension and renal failure. Blood transfusion and the development of acute kidney injury lead to both short-term and long-term poor patient outcomes, including an increased risk of death, graft failure, length of stay and reduced quality of life. Octreotide may reduce the incidence of renal dysfunction, perioperative haemorrhage and enhance intraoperative blood pressure. However, octreotide does have risks, including resistant bradycardia, hyperglycaemia and hypoglycaemia and QT prolongation. Hence, a randomised controlled trial of octreotide during liver transplantation is needed to determine the cost-efficacy and safety of its use; this study represents a feasibility study prior to this trial. METHODS AND ANALYSIS: We describe a multicentre, double-blind, randomised, placebo-controlled feasibility study of continuous infusion of octreotide during liver transplantation surgery. We will recruit 30 adult patients at two liver transplant centres. A blinded infusion during surgery will be administered in a 2:1 ratio of octreotide:placebo. The primary outcomes will determine the feasibility of this study design. These include the recruitment ratio, correct administration of blinded study intervention, adverse event rates, patient and clinician enrolment refusal and completion of data collection. Secondary outcome measures of efficacy and safety will help shape future trials by assessing potential primary outcome measures and monitoring safety end points. No formal statistical tests are planned. This manuscript represents study protocol number 1.3, dated 2 June 2021. ETHICS AND DISSEMINATION: This study has received Research Ethics Committee approval. The main study outcomes will be submitted to an open-access journal. TRIAL SPONSOR: The Joint Research Office, University College London, UK.Neither the sponsor nor the funder have any role in study design, collection, management, analysis and interpretation of data, writing of the study report or the decision to submit the report for publication. TRIAL REGISTRATION: The study is registered with ClinicalTrials.gov (NCT04941911) with recruitment due to start in August 2021 with anticipated completion in July 2022. CLINICAL TRIALS UNIT: Surgical and Interventional Group, Division of Surgery & Interventional Science, University College London.

Prospective Cohort Study Assessing the Use of Peripheral Saphenous Venous Pressure Monitoring as a Marker of the Transcaval Venous Pressure Gradient in Liver Transplant Surgery.

OBJECTIVES: Assessment of the transcaval venous pressure gradient, the central venous to inferior vena caval pressure, assists anesthetists and surgeons in management of liver transplant recipients. Traditionally, this entails insertion of a femoral central line with increased patient risk and health care cost. Here, we assessed the ability of a saphenous vein cannula to act as a surrogate for the femoral central line as a means to assess the transcaval pressure gradient in a safer and less invasive manner. MATERIALS AND METHODS: A prospective cohort of 22 patients undergoing liver transplant underwent saphenous vein cannulation in addition to insertion of a femoral and internal jugular central venous catheter. Data were collected throughout each phase of surgery to assess the central, femoral, and saphenous vein pressures; results of a range of relevant physiological and ventilatory data were also collected. RESULTS: The primary outcome, the correlation between saphenous and femoral venous pressure throughout surgery, was acceptable (r2 = 0.491, P < .001). During the anhepatic phase of surgery, this correlation improved (r2 = 0.912, P < .001). The correlation between the femoral to central venous pressure and saphenous to central venous pressure gradients was also reasonable throughout surgery (r2 = 0.386, P < .001), and this correlation was significantly stronger during the anhepatic phase (r2 = 0.935, P < .001). CONCLUSIONS: Saphenous venous pressure, provided by peripheral cannulation, provided a reliable, less invasive, and safer alternative to femoral central line insertion for determination of the transcaval pressure gradient during the anhepatic phase of liver transplant.

Quantitative FLAIR MRI in Amyotrophic Lateral Sclerosis.

RATIONALE AND OBJECTIVES: T2-weighted magnetic resonance imaging (MRI) hyperintensity assessed visually in the corticospinal tract (CST) lacks sensitivity for a diagnosis of amyotrophic lateral sclerosis (ALS). We sought to explore a quantitative approach to fluid-attenuated inversion recovery (FLAIR) MRI intensity across a range of ALS phenotypes. MATERIALS AND METHODS: Thirty-three classical ALS patients, 10 with a flail arm presentation, and six with primary lateral sclerosis underwent MRI at 3 Tesla. Comparisons of quantitative FLAIR intensity in the CST and corpus callosum were made between 21 healthy controls and within patient phenotypic subgroups, some of whom were studied longitudinally. RESULTS: Mean FLAIR intensity was greater in patient groups. The cerebral peduncle intensity provided the strongest subgroup classification. FLAIR intensity increased longitudinally. The rate of change of FLAIR within CST correlated with rate of decline in executive function and ALS functional rating score. CONCLUSIONS: FLAIR MRI encodes quantifiable information of potential diagnostic, stratification, and monitoring value.