Antiphospholipid antibodies and antiphospholipid syndrome.

Individuals with antiphospholipid syndrome (APS) have antibodies directed against phospholipid-binding proteins (aPL). The condition is most associated with an increased risk of thromboembolism and obstetric complications. The 2023 classification criteria for APS include six clinical domains (venous thromboembolism, arterial thrombosis, microvascular events, obstetric events, cardiac valve, thrombocytopaenia) and two laboratory domains (lupus anticoagulant, and anti-cardiolipin or anti-ß2-glycoprotein-I antibodies). Diagnosis and treatment of APS are specialist tasks and are summarised in this review.

Moving together - benefits of an online dance program on physical and mental health for older women: an exploratory mixed-method study.

BACKGROUND: Previous studies show that in-person dance training is a beneficial form of physical activity that involves mental, social, and physical dimensions. This exploratory study investigated the benefits of a 12-week online dance training intervention on mental and physical health outcomes for older women. METHODS: A convergent parallel mixed-method design was used. Forty-five older adults (74.0 ± 5.3 yrs old, 44 women) were recruited through advertisements at activity and rehabilitation centers in the North Denmark region. The intervention consisted of two weekly 60-min classes of improvisation and salsa delivered online through video call applications. Changes in physical health outcomes (body mass and composition, resting blood pressure, Senior Fitness Test battery) and self-rated health and wellbeing (health-related quality of life (HRQOL), feelings of loneliness) were assessed prior to and after 12 weeks of dancing. Focus group interviews were conducted post-intervention to further explore the benefits as well as the participant's experience of the intervention. Thematic analysis of the qualitative data was conducted. RESULTS: Thirty-two participants (all women) completed the study. Significant improvements in fitness were found for the number of arm curls performed (baseline: 12.3 ± 3.0; post-intervention: 13.7 ± 3.0, P = 0.005), 2-min step test performance (baseline: 66.5 ± 20.0 reps.; post-intervention: 73.8 ± 22.6 reps., P = 0.016), and chair sit-and-reach (baseline: 0.4 ± 11.3 cm; post-intervention: 5.5 ± 10.1 cm, P < 0.001). There was a significant increase in body mass from baseline to post-intervention (P < 0.015). The themes from the focus groups included (1) Participation, (2) Challenges, (3) Progression, (4) Motivation, (5) Perceived health and wellbeing, and (6) Online dance instruction. No significant changes were reported in HRQOL and loneliness from the quantitative data, although the qualitative data did reveal improved feelings of physical health and wellbeing. CONCLUSIONS: The intervention improved several aspects of fitness in older women and improved the participants' perceptions of their own physical abilities and wellbeing. While most participants found the online intervention enjoyable, several participants missed the feedback from the instructors that naturally occurs with in-person instruction.

Unveiling the Temporal Aspect of MRI Tattoo Reactions: A Prospective Evaluation of a Newly-Acquired Tattoo with Multiple MRI Scans.

BACKGROUND Over the past 30 years, painful reactions during magnetic resonance imaging (MRI) in tattooed individuals have been sporadically reported. These complications manifest as burning pain in tattooed skin areas, occasionally with swelling and redness, often leading to termination of the scanning. The exact cause is unclear, but iron oxide pigments in permanent make-up or elements in carbon black tattoos may play a role. Additionally, factors like tattoo age, design, and color may influence reactions. The existing literature lacks comprehensive evidence, leaving many questions unanswered. CASE REPORT We present the unique case of a young man who experienced recurring painful reactions in a recently applied black tattoo during multiple MRI scans. Despite the absence of ferrimagnetic ingredients in the tattoo ink, the patient reported intense burning sensations along with transient erythema and edema. Interestingly, the severity of these reactions gradually decreased over time, suggesting a time-dependent factor contributing to the problem. This finding highlights the potential influence of pigment particle density in the skin on the severity and risk of MRI interactions. We hypothesize that the painful sensations could be triggered by excitation of dermal C-fibers by conductive elements in the tattoo ink, likely carbon particles. CONCLUSIONS Our case study highlights that MRI-induced tattoo reactions may gradually decrease over time. While MRI scans occasionally can cause transient reactions in tattoos, they do not result in permanent skin damage and remain a safe and essential diagnostic tool. Further research is needed to understand the mechanisms behind these reactions and explore preventive measures.

Ventriculostomy-associated infection (VAI) in patients with acute brain injury-a retrospective study.

BACKGROUND: Ventriculostomy-associated infection (VAI) is common after external ventricular drains (EVD) insertion but is difficult to diagnose in patients with acute brain injury. Previously, we proposed a set of criteria for ruling out VAI in traumatic brain injury. This study aimed to validate these criteria. For exploratory purposes, we sought to develop and validate a score for VAI risk assessment in patients with different types of severe acute brain injury. METHODS: This retrospective cohort study included adults with acute brain injury who received an EVD and in whom CSF samples were taken over a period of 57 months. As standard non-coated bolt-connected EVDs were used. The predictive performance of biomarkers was analyzed as defined previously. A multivariable regression model was performed with five variables. RESULTS: A total of 683 patients with acute brain injury underwent EVD placement and had 1272 CSF samples; 92 (13.5%) patients were categorized as culture-positive VAI, 130 (19%) as culture-negative VAI, and 461 (67.5%) as no VAI. A low CSF WBC/RBC ratio (< 0.037), high CSF/plasma glucose ratio (> 0.6), and low CSF protein (< 0.5g/L) showed a positive predictive value of 0.09 (95%CI, 0.05-0.13). In the multivariable logistic regression model, days to sample (OR 1.09; 95%CI, 1.03-1.16) and CSF WBC/RBC ratio (OR 34.86; 95%CI, 3.94-683.15) were found to predict VAI. CONCLUSION: In patients with acute brain injury and an EVD, our proposed combined cut-off for ruling out VAI performed satisfactorily. Days to sample and CSF WBC/RBC ratio were found independent predictors for VAI in the multivariable logistic regression model.

Study protocol for the ACTIVE SCHOOL study investigating two different strategies of physical activity to improve academic performance in Schoolchildren.

BACKGROUND: Previous research has suggested that school-based physical activity (PA) interventions may have a positive impact on academic performance. However, existing literature on school-based interventions encompasses various forms of PA, spanning from vigorous intensity PA outside the academic classes to light intensity PA and movement integrated into academic learning tasks, and results on academic performance are inconclusive. ACTIVE SCHOOL will implement two different PA interventions for one school year and assess the effects on the pupils' academic performance, with math performance as the primary outcome. METHODS/DESIGN: The ACTIVE SCHOOL project consists of two phases: 1) Development phase and 2) Randomized Controlled Trial (RCT). In phase one, two interventions were developed in collaboration with school staff. The two interventions were tested in an 8-weeks feasibility study. In phase two, a RCT-study with three arms will be conducted in 9-10-year-old children for one school year. The RCT-study will be carried out in two intervention rounds during the school years 2023/2024 and 2024/2025. Schools will be randomized to one of two interventions or control;1) Run, Jump & Fun intervention (4 × 30 min/week of moderate-to-vigorous physical activity; 2) Move & Learn intervention (4 × 30 min/week focusing on embodied learning in math and Danish lessons); or 3) a control condition, consisting of normal teaching practices. Outcome measures include academic performance, PA level, cognitive functions, cardiorespiratory fitness, anthropometry, well-being and school motivation (collected before, during and after the intervention period). A process evaluation will be conducted to assess implementation. DISCUSSION: The ACTIVE SCHOOL study will expand knowledge regarding the impact of PA on academic performance. The study will have the potential to significantly contribute to future research, as well as the scientific and educational debate on the best way to implement PA to support education and learning. TRIAL REGISTRATION: The study was registered on the 25th of October 2022 in ClinicalTrials.gov, NCT05602948.

Computer-Assisted Intramedullary Nailing of Intertrochanteric Fractures Did Not Prevent Tip-Apex Distance Outliers.

Intertrochanteric femoral fractures are commonly treated with intramedullary nails (IMNs). A tip-apex distance (TAD) of more than 20-25 mm is associated with an increased risk of cut-out. The Stryker Adaptive Positioning System (ADAPT) is a computer-assisted navigation system designed to reduce TADs. We aim to assess if the ADAPT reduces the number of outliers with a TAD > 20 mm. All patients with intertrochanteric fractures treated with an IMN between 1 September 2020 and 12 March 2022 were included. Patients were included in three periods: a pre-ADAPT period (55 patients); an ADAPT period (50 patients), where it was compulsory to use the system; and a post-ADAPT period after the discontinuation of the system (59 patients). The TADs and lag screw protrusions beyond the lateral cortex were measured. The median TADs in the three periods were 17.0 mm (8-31 mm), 15.5 mm (9-30 mm), and 18.0 mm (11-32 mm), respectively. The absolute number of outliers with a TAD > 20 mm decreased from 15/55 patients in the pre-ADAPT period to 11/50 patients during the ADAPT period. This observation was not statistically significant, but this is likely due to the lack of power of the present study to show changes of this magnitude. However, our expectation that the ADAPT would diminish outliers markedly or close to zero outliers was not met, as we observed 11/50 = 22% outliers with a TAD > 20 mm when using computer-assisted surgery, i.e., ADAPT and Gamma3 for intertrochanteric fractures. Based on these findings, the use of the ADAPT was discontinued at our level 1 trauma center.

MRI-Induced Neurosensory Events in Decorative Black Tattoos: Study by Advanced Experimental Methods.

Adverse reactions in tattooed skin during magnetic resonance imaging (MRI) are rare but well known. Previous reports describe sudden burning pain in tattooed skin, sometimes accompanied by mild erythema and oedema when entering MRI scanners. The pathophysiology remains unclear, but simple direct thermal heating can be excluded. It has been hypothesized that MRI-triggered torque and traction create neural sensations from magnetic pigment particles. However, this case enlightens yet another possible mechanism. We present a 35-year-old woman experiencing reoccurring stinging sensations in three decorative black tattoos just seconds after the initiation of the MRI. Single-blind tests with handheld power magnets or a dummy could reproduce painful subjective feelings in her tattooed skin. Similar events were provoked during re-evaluation with MRI. Surprisingly, chemical analyses and electron microscopy of skin samples revealed carbon black as the colouring agent - no iron-based solids were detected. Our case demonstrates that MRI tattoo reactions are not limited to magnetic contaminants alone. More distinct subgroups of MRI-induced reactions may occur. We hypothesize that radiofrequency induction of surface currents in black carbon particles adjacent to sensory axons in the dermis may lead to neurosensations.

Epidemiological description and trajectories of patients with prostate cancer in Denmark: an observational study of 7448 patients.

OBJECTIVE: Identification of patients at high risk of aggressive prostate cancer is a major clinical challenge. With the view of developing artificial intelligence-based methods for identification of these patients, we are constructing a comprehensive clinical database including 7448 prostate cancer (PCa) Danish patients. In this paper we provide an epidemiological description and patients' trajectories of this retrospective observational population, to contribute to the understanding of the characteristics and pathways of PCa patients in Denmark. RESULTS: Individuals receiving a PCa diagnosis during 2008-2014 in Region Southern Denmark were identified, and all diagnoses, operations, investigations, and biochemistry analyses, from 4 years prior, to 5 years after PCa diagnosis were obtained. About 85.1% were not diagnosed with metastatic PCa during the study period (unaggressive PCa); 9.2% were simultaneously diagnosed with PCa and metastasis (aggressive-advanced PCa), while 5.7% were not diagnosed with metastatic PCa at first, but they were diagnosed with metastasis at some point during the 5 years follow-up (aggressive-not advanced PCa). Patients with unaggressive PCa had more clinical investigations directly related to PCa detection (prostate ultrasounds and biopsies) during the 4 years prior to PCa diagnosis, compared to patients with aggressive PCa, which may have contributed to the early detection of PCa.

Geometric distortions in clinical MRI sequences for radiotherapy: insights gained from a multicenter investigation.

BACKGROUND: As magnetic resonance imaging (MRI) becomes increasingly integrated into radiotherapy (RT) for enhanced treatment planning and adaptation, the inherent geometric distortion in acquired MR images pose a potential challenge to treatment accuracy. This study aimed to evaluate the geometric distortion levels in the clinical MRI protocols used across Danish RT centers and discuss influence of specific sequence parameters. Based on the variety in geometric performance across centers, we assess if harmonization of MRI sequences is a relevant measure. MATERIALS AND METHODS: Nine centers participated with 12 MRI scanners and MRI-Linacs (MRL). Using a travelling phantom approach, a reference MRI sequence was used to assess variation in baseline distortion level between scanners. The phantom was also scanned with local clinical MRI sequences for brain, head/neck (H/N), abdomen, and pelvis. The influence of echo time, receiver bandwidth, image weighting, and 2D/3D acquisition was investigated. RESULTS: We found a large variation in geometric accuracy across 93 clinical sequences examined, exceeding the baseline variation found between MRI scanners (σ = 0.22 mm), except for abdominal sequences where the variation was lower. Brain and abdominal sequences showed lowest distortion levels ([0.22, 2.26] mm), and a large variation in performance was found for H/N and pelvic sequences ([0.19, 4.07] mm). Post hoc analyses revealed that distortion levels decreased with increasing bandwidth and a less clear increase in distortion levels with increasing echo time. 3D MRI sequences had lower distortion levels than 2D (median of 1.10 and 2.10 mm, respectively), and in DWI sequences, the echo-planar imaging read-out resulted in highest distortion levels. CONCLUSION: There is a large variation in the geometric distortion levels of clinical MRI sequences across Danish RT centers, and between anatomical sites. The large variation observed makes harmonization of MRI sequences across institutions and adoption of practices from well-performing anatomical sites, a relevant measure within RT.

Impact of upper-body ergometer rowing exercise on aerobic fitness and cardiometabolic disease risk in individuals with spinal cord injury: A 6-month follow-up study.

OBJECTIVE: We recently demonstrated that upper-body rowing exercise (UBROW) improved aerobic fitness in individuals with spinal cord injury (SCI), with no effect on traditional cardiometabolic risk factors. Here, we tested the hypothesis that the exercise-induced increase in aerobic fitness was maintained at 6-month (6M) follow-up. DESIGN: Six-month follow-up. SETTING: University/hospital. PARTICIPANTS: Seventeen wheelchair-dependent participants with SCI. INTERVENTIONS: 12-week of exercise training (UBROW) or control (CON). OUTCOME MEASURES: Aerobic fitness (POpeak and V̇O2peak), body composition, blood pressure, and blood biomarkers of cardiometabolic risk were assessed at 6M follow-up and compared to baseline (BL) and immediately post-intervention (12-week). Minutes of mild, moderate, and heavy intensity leisure time physical activity (LTPA) were assessed by self-report. RESULTS: Fourteen participants returned at 6M follow-up (CON, n = 6; UBROW, n = 8). In UBROW, POpeak (median (Q1-Q3)) increased from BL (70 W (37-84)) to 12-week (77 W (58-109), P = 0.01) and 6M follow-up (81 W (51-96), P = 0.01), with no difference between 12-week and 6M follow-up (P = 0.21). Similarly, V̇O2peak increased from BL (15.4 ml/kg/min (10.5-19.4)) to 12-week (16.6 ml/kg/min (12.8-21.3), P = 0.01) with no difference between 12-week and 6M follow-up (16.3 ml/kg/min (12.9-19.7), P = 0.74). No differences were found in CON for either POpeak (P = 0.22) or V̇O2peak (P = 0.27). There were no changes over time in traditional cardiometabolic risk factors or for minutes of different LTPA intensities. CONCLUSION: We demonstrate that improvements in aerobic fitness are maintained for at least six months after completion of a 12-week exercise intervention, supporting the use of periodic exercise interventions to boost aerobic fitness level in individuals with SCI.Trial registration: ClinicalTrials.gov identifier: NCT04390087..

Doctors Identify Hemorrhage Better during Chart Review when Assisted by Artificial Intelligence.

OBJECTIVES: This study evaluated if medical doctors could identify more hemorrhage events during chart review in a clinical setting when assisted by an artificial intelligence (AI) model and medical doctors' perception of using the AI model. METHODS: To develop the AI model, sentences from 900 electronic health records were labeled as positive or negative for hemorrhage and categorized into one of 12 anatomical locations. The AI model was evaluated on a test cohort consisting of 566 admissions. Using eye-tracking technology, we investigated medical doctors' reading workflow during manual chart review. Moreover, we performed a clinical use study where medical doctors read two admissions with and without AI assistance to evaluate performance when using and perception of using the AI model. RESULTS: The AI model had a sensitivity of 93.7% and a specificity of 98.1% on the test cohort. In the use studies, we found that medical doctors missed more than 33% of relevant sentences when doing chart review without AI assistance. Hemorrhage events described in paragraphs were more often overlooked compared with bullet-pointed hemorrhage mentions. With AI-assisted chart review, medical doctors identified 48 and 49 percentage points more hemorrhage events than without assistance in two admissions, and they were generally positive toward using the AI model as a supporting tool. CONCLUSION: Medical doctors identified more hemorrhage events with AI-assisted chart review and they were generally positive toward using the AI model.

Tuning magnetoelectricity in a mixed-anisotropy antiferromagnet.

Control of magnetization and electric polarization is attractive in relation to tailoring materials for data storage and devices such as sensors or antennae. In magnetoelectric materials, these degrees of freedom are closely coupled, allowing polarization to be controlled by a magnetic field, and magnetization by an electric field, but the magnitude of the effect remains a challenge in the case of single-phase magnetoelectrics for applications. We demonstrate that the magnetoelectric properties of the mixed-anisotropy antiferromagnet LiNi1-xFexPO4 are profoundly affected by partial substitution of Ni2+ ions with Fe2+ on the transition metal site. This introduces random site-dependent single-ion anisotropy energies and causes a lowering of the magnetic symmetry of the system. In turn, magnetoelectric couplings that are symmetry-forbidden in the parent compounds, LiNiPO4 and LiFePO4, are unlocked and the dominant coupling is enhanced by almost two orders of magnitude. Our results demonstrate the potential of mixed-anisotropy magnets for tuning magnetoelectric properties.

High-power supercontinuum lasers with a flat blue spectrum through pump modulation: a numerical study.

We numerically investigate high-power, modulational instability-based supercontinuum sources. Such sources have spectra that reach the infrared material absorption edge and as a result the spectrum has a strong narrow blue peak (dispersive wave group velocity matched to solitons at the infrared loss edge) followed by a significant dip in the neighboring longer-wavelength region. In a wide range of applications one prefers a broader and more flat blue part within a certain minimum and maximum power spectral density. From the perspective of fiber degradation it would be desirable to achieve this at reduced pump peak powers. We show that it is possible to improve the flatness by more than a factor of 3 by modulating the input peak power, although this comes at the expense of slightly higher relative intensity noise. Specifically, we consider a standard 6.6 W, 80 MHz supercontinuum source with a 455 nm blue edge, which uses 7 ps pump pulses. We then modulate its peak power to generate a pump pulse train having two and three different sub-pulses.

On the mechanism of painful burn sensation in tattoos on magnetic resonance imaging (MRI). Magnetic substances in tattoo inks used for permanent makeup (PMU) identified: Magnetite, goethite, and hematite.

BACKGROUND: Persons with cosmetic tattoos occasionally experience severe pain and burning sensation on magnetic resonance imaging (MRI). OBJECTIVE: To explore the culprit magnetic substances in commonly used permanent makeup inks. MATERIAL AND METHODS: 20 inks used for cosmetic tattooing of eyebrows, eyeliners, and lips were selected. Ink bottles were tested for magnetic behavior with a neodymium magnet. Eight iron oxide inks qualified for the final study. Metals were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The magnetic fraction of inks was isolated and analyzed by X-ray fluorescence (XRF). Magnetic iron compounds were characterized by Mössbauer spectroscopy and powder X-ray diffraction (XRD). RESULTS: ICP-MS showed iron in all magnetic samples, and some nickel and chromium. Mössbauer spectroscopy and XRD detected ferromagnetic minerals, particularly magnetite, followed by goethite and hematite. CONCLUSION: This original study of cosmetic ink stock products made with iron oxide pigments reports magnetic impurities in inks for cosmetic tattooing, e.g., magnetite, goethite, and hematite. These may be the main cause of MRI burn sensation in cosmetic tattoos. The mechanism behind sensations is hypothesized to be induction of electrical stimuli of axons from periaxonal pigment/impurity activated by magnetic force. Magnetite is considered the lead culprit.

Change in treatment preferences in pediatric diaphyseal forearm fractures: a Danish nationwide register study of 36,244 fractures between 1997 and 2016.

BACKGROUND AND PURPOSE: The choice between invasive and non-invasive treatment of diaphyseal forearm fractures in children can be difficult. We investigated the trends in choice of treatment of pediatric diaphyseal forearm fractures over a 20-year period.  Patients and methods: This is a population-based register study with data from 1997 to 2016 retrieved from the Danish National Patient Registry. The primary outcome was choice of primary treatment within 1 week divided into non-invasive treatment (casting only or closed reduction including casting) and invasive (Kirshner wires, intramedullary nailing [IMN], and open reduction internal fixation [ORIF]). The secondary outcomes were further sub-analyses on invasive treatment and age groups. RESULTS: 36,244 diaphyseal forearm fractures were investigated, yielding a mean incidence of 172 per 105/year. The proportion of fractures treated invasively increased from 1997 to 2016, from 4% to 23%. The use of Kirschner wires increased from 1% to 9%, IMN increased from 1% to 14%, and ORIF decreased from 2% to 1%. The changes were evident in all age groups but smaller in the 0-3-year age group. CONCLUSION: We found an increase in invasive treatment of pediatric diaphyseal forearm fractures over the investigated period. A change in invasive methods was also found, as the rate of IMN increased over the investigated period and became the predominant surgical treatment choice.

Rowing exercise increases cardiorespiratory fitness and brachial artery diameter but not traditional cardiometabolic risk factors in spinal cord-injured humans.

PURPOSE: This study assessed the effects of upper-body rowing exercise on cardiorespiratory fitness, traditional cardiometabolic risk factors, and vascular health in individuals with spinal cord injury (SCI). METHODS: Seventeen male and female adults with chronic (> 1 yr) motor-complete and incomplete SCI (level of injury: C4-L3) were randomized to control (CON, n = 9) or exercise (UBROW, n = 8). Participants in UBROW performed 12-week, 3 weekly sessions of 30-min upper-body ergometer rowing exercise, complying with current exercise guidelines for SCI. Cardiorespiratory fitness ([Formula: see text]O2peak), traditional risk factors (lipid profile, glycemic control) as well as inflammatory and vascular endothelium-derived biomarkers (derived from fasting blood samples) were measured before and after 6 (6W) and 12 weeks (12W). Brachial artery resting diameter and flow-mediated dilation (FMD) were determined by ultrasound as exploratory outcomes. RESULTS: UBROW increased [Formula: see text]O2peak from baseline (15.1 ± 5.1 mL/kg/min; mean ± SD) to 6W (16.5 ± 5.3; P < 0.01) and 12W (17.5 ± 6.1; P < 0.01). UBROW increased resting brachial artery diameter from baseline (4.80 ± 0.72 mm) to 12W (5.08 ± 0.91; P < 0.01), with no changes at 6W (4.96 ± 0.91), and no changes in CON. There were no significant time-by-group interactions in traditional cardiometabolic blood biomarkers, or in unadjusted or baseline diameter corrected FMD. Explorative analyses revealed inverse correlations between changes (∆12W-baseline) in endothelin-1 and changes in resting diameter (r = - 0.56) and FMD% (r = - 0.60), both P < 0.05. CONCLUSION: These results demonstrate that 12 weeks of upper-body rowing complying with current exercise guidelines for SCI improves cardiorespiratory fitness and increases resting brachial artery diameter. In contrast, the exercise intervention had no or only modest effects on traditional cardiometabolic risk factors. The study was registered at Clinicaltrials.gov (N-20190053, May 15, 2020).

Comparison of plasma total carbon dioxide and standard hydrogen carbonate in a hospital laboratory setting.

BACKGROUND: Studies comparing venous total carbon dioxide (tCO2) and standard hydrogen carbonate (HCO3-(P,st)) has shown diverse results, and it is debatable whether these two parameters can be used interchangeably for workup of acid-base disorders in a hospital setting. METHOD: All patients with an HCO3-(P,st) requisition from any department at Odense University Hospital between 11th May 2021 and 1st June 2021 had tCO2 and HCO3-(P,st) analysed simultaneously. TCO2 was measured on Cobas® 8000, c702 module, while HCO3-(P,st) was calculated based on measurements on ABL835 Flex. RESULTS: From 1210 patients, mean (standard deviation (SD)) was 22.9 (3.7) mmol/L for tCO2 and 22.5 (2.9) mmol/L for HCO3-(P,st). TCO2 range was 10.1-42.3 mmol/L and 11.7-41.4 mmol/L for HCO3-(P,st). Linear regression showed that tCO2 (mmol/L) = -2.90 + 1.15 × HCO3-(P,st) (mmol/L) with R2 = 0.81. Bias (mean (SD) difference) between tCO2 and HCO3-(P,st)) was 0.4 (1.7) mmol/L with a -5.0-9.6 mmol/L range. Limits of agreement was -2.90-3.70 mmol/L. Comparison of classification within, above or below reference interval for tCO2 and HCO3-(P,st) showed that 984 samples (81%) retained their classification. Only one sample (0.1%) would be severely misclassified (outside the respective reference intervals) if HCO3-(P,st) was considered the gold standard. Of the samples investigated, 46.1% had a mean difference between tCO2 and HCO3-(P,st) of 0-1 mmol/L and 30.3% had 1.1-2.0 mmol/L. CONCLUSIONS: Our results indicate that venous tCO2 and venous HCO3-(P,st) can be used interchangeably in a hospital setting for workup of acid-base disorders.