Dynamic prediction of mortality in COVID-19 patients in the intensive care unit: A retrospective multi-center cohort study.

Background: The COVID-19 pandemic continues to overwhelm intensive care units (ICUs) worldwide, and improved prediction of mortality among COVID-19 patients could assist decision making in the ICU setting. In this work, we report on the development and validation of a dynamic mortality model specifically for critically ill COVID-19 patients and discuss its potential utility in the ICU. Methods: We collected electronic medical record (EMR) data from 3222 ICU admissions with a COVID-19 infection from 25 different ICUs in the Netherlands. We extracted daily observations of each patient and fitted both a linear (logistic regression) and non-linear (random forest) model to predict mortality within 24 h from the moment of prediction. Isotonic regression was used to re-calibrate the predictions of the fitted models. We evaluated the models in a leave-one-ICU-out (LOIO) cross-validation procedure. Results: The logistic regression and random forest model yielded an area under the receiver operating characteristic curve of 0.87 [0.85; 0.88] and 0.86 [0.84; 0.88], respectively. The recalibrated model predictions showed a calibration intercept of -0.04 [-0.12; 0.04] and slope of 0.90 [0.85; 0.95] for logistic regression model and a calibration intercept of -0.19 [-0.27; -0.10] and slope of 0.89 [0.84; 0.94] for the random forest model. Discussion: We presented a model for dynamic mortality prediction, specifically for critically ill COVID-19 patients, which predicts near-term mortality rather than in-ICU mortality. The potential clinical utility of dynamic mortality models such as benchmarking, improving resource allocation and informing family members, as well as the development of models with more causal structure, should be topics for future research.

Attitudes of Dutch intensive care unit clinicians towards oxygen therapy.

BACKGROUND: Over the last decade, there has been an increasing awareness for the potential harm of the administration of too much oxygen. We aimed to describe self-reported attitudes towards oxygen therapy by clinicians from a large representative sample of intensive care units (ICUs) in the Netherlands. METHODS: In April 2019, 36 ICUs in the Netherlands were approached and asked to send out a questionnaire (59 questions) to their nursing and medical staff (ICU clinicians) eliciting self-reported behaviour and attitudes towards oxygen therapy in general and in specific ICU case scenarios. RESULTS: In total, 1361 ICU clinicians (71% nurses, 24% physicians) from 28 ICUs returned the questionnaire. Of responding ICU clinicians, 64% considered oxygen-induced lung injury to be a major concern. The majority of respondents considered a partial pressure of oxygen (PaO2) of 6-10 kPa (45-75 mmHg) and an arterial saturation (SaO2) of 85-90% as acceptable for 15 minutes, and a PaO2 7-10 kPa (53-75 mmHg) and SaO2 90-95% as acceptable for 24-48 hours in an acute respiratory distress syndrome (ARDS) patient. In most case scenarios, respondents reported not to change the fraction of inspired oxygen (FiO2) if SaO2 was 90-95% or PaO2 was 12 kPa (90 mmHg). CONCLUSION: A representative sample of ICU clinicians from the Netherlands were concerned about oxygen-induced lung injury, and reported that they preferred PaO2 and SaO2 targets in the lower physiological range and would adjust ventilation settings accordingly.

Influence of Small Vessel Disease and Microstructural Integrity on Neurocognitive Functioning in Older Individuals: The DANTE Study Leiden.

BACKGROUND AND PURPOSE: Small vessel disease is a major cause of neurocognitive dysfunction in the elderly. Small vessel disease may manifest as white matter hyperintensities, lacunar infarcts, cerebral microbleeds, and atrophy, all of which are visible on conventional MR imaging or as microstructural changes determined by diffusion tensor imaging. This study investigated whether microstructural integrity is associated with neurocognitive dysfunction in older individuals, irrespective of the conventional features of small vessel disease. MATERIALS AND METHODS: The study included 195 participants (75 years of age or older) who underwent conventional 3T MR imaging with DTI to assess fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. Cognitive tests were administered to assess cognitive domains, and the Geriatric Depression Scale-15 and Apathy Scale of Starkstein were used to assess symptoms of depression and apathy, respectively. The association between DTI measures and neurocognitive function was analyzed by using linear regression models. RESULTS: In gray matter, a lower fractional anisotropy and higher mean diffusivity, axial diffusivity, and radial diffusivity were associated with worse executive function, psychomotor speed, and overall cognition and, in white matter, also with memory. Findings were independent of white matter hyperintensities, lacunar infarcts, and cerebral microbleeds. However, after additional adjustment for normalized brain volume, only lower fractional anisotropy in white and gray matter and higher gray matter radial diffusivity remained associated with executive functioning. DTI measures were not associated with scores on the Geriatric Depression Scale-15 or the Apathy Scale of Starkstein. CONCLUSIONS: Microstructural integrity was associated with cognitive but not psychological dysfunction. Associations were independent of the conventional features of small vessel disease but attenuated after adjusting for brain volume.

In depressed older persons higher blood pressure is associated with symptoms of apathy. The NESDO study.

BACKGROUND: In older persons, a relationship between both higher and lower blood pressure and depression has inconsistently been reported. Blood pressure may be differentially associated with distinct symptom domains of depression. We examined the cross-sectional relation of current systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) with different depressive symptom domains among depressed older persons. METHODS: In the Netherlands Study of Depression in Older Persons (NESDO), 270 participants aged 60 years and above were diagnosed with depression in the past month. Using the three corresponding subscales of the Inventory of Depressive Symptoms-Self Report (IDS-SR), motivational, mood and somatic symptom domains were assessed. Additionally, symptoms of apathy were determined with the Apathy Scale. Multiple linear regression was used to examine the cross-sectional relationship between current SBP, DBP and MAP with both IDS-SR subscale and Apathy Scale scores. Unstandardized betas were calculated per 10 mmHg increase in blood pressure measures. RESULTS: Mean age of participants was 70.4 years (standard deviation 7.3). Higher SBP (Beta 0.33, t (254) = 2.01, p = 0.045), higher DBP (Beta 0.68, t (254) = 2.15, p = 0.03) and higher MAP (Beta 0.63, t (254) = 2.33, p = 0.02) were associated with higher Apathy Scale scores in the fully adjusted model. Furthermore, a higher SBP was associated with higher IDS-SR mood subscale scores (Beta 0.25, t (254) = 2.13, p = 0.03). CONCLUSIONS: Depressed older people with higher blood pressure measures had particularly more symptoms of apathy. To disentangle the relationship of blood pressure with late-life depression, it is important to pay attention to the role of apathy symptoms.

Improved quality of care for patients undergoing an abdominoperineal excision for rectal cancer.

INTRODUCTION: New diagnostics, the emergence of total mesorectal excision and neoadjuvant treatments have improved outcome for patients with rectal cancer. Patients with distal rectal cancer undergoing an abdominoperineal excision seem to do worse compared to those treated with sphinctersparing techniques. The aim of this study was to evaluate the quality of care for patients undergoing an abdominoperineal excision for distal rectal cancer during the last 15 years. MATERIALS AND METHODS: All patients with rectal cancer, who underwent an abdominoperineal excision between December 1996 and December 2010 in 5 Dutch hospitals were analysed. Patients were divided into three cohorts; 1996-2001, 2001-2005 and 2006-2010. All data was extracted from medical records. RESULTS: 477 patients were identified. There was no significant difference in sex, age, BMI, prior pelvic surgery and ASA stages between the cohorts. MRI became a standard tool in the work-up, the use increased from 4.5% in the first, to 95.1% in the last cohort (p < 0.0001). Neoadjuvant treatment shifted from predominantly none (64.9% in cohort 1) to short course radiotherapy (66.7% in cohort 2) and chemoradiation therapy (55.7% in cohort 3). There was a trend towards a decreased circumferential resection margin involvement in the cohorts (18.8%, 16.7% and 11.4%; p = 0.142). Accidental bowel perforations have significantly decreased from 28.6%, and 21.7% to 9.2% in cohort 3 (p < 0.0001). CONCLUSION: Significant improvements in work-up, neoadjuvant and surgical treatment have been made for patients with low rectal cancer, undergoing an abdominoperineal excision. These improvements result in improved short term outcome.

Evaluation of the threshold value for the Early Warning Score on general wards.

INTRODUCTION: The Early Warning Score (EWS) is used for early detection of deteriorating vital parameters and has been correlated with adverse outcomes. Unfortunately, neither its value on general wards nor the optimal cut-off value have been investigated. We aimed to find the optimal cut-off value for EWS on general wards, and investigated the possibility to raise this value from EWS ≥ 3 without compromising sensitivity too much. METHODS: From May 2010 until May 2011, EWS was calculated from vital parameters in all patients in medical and surgical wards in the Medical Centre Alkmaar. Cut-off value was defined as EWS ≥ 3, unless otherwise specified. Six responses were defined and categorised as interventions (infusion prescription, medication changes, ICU consultation) and other actions (no action, change EWS cut-off value, oxygen supplementation), and it was registered whenever the threshold was exceeded. RESULTS: 71,911 EWS values were obtained, 31,728 (44%) on medical wards and 40,183 (56%) on surgical wards. On medical wards, the cut-off value was exceeded 3734 times, and response was registered in 29% of the cases with 141 (12%) interventions. On surgical wards, the cut-off value was exceeded 3279 times, and response was registered in 19% of the cases with 633 (36%) interventions. Sensitivity and specificity for EWS ≥ 3 could not be calculated. For a calculated cut-off at EWS ≥ 4, sensitivity decreased to 74%. CONCLUSION: Raising the EWS threshold to 4 on general wards in the hospital would lead to an unacceptable decrease in sensitivity. Therefore, we recommend that the pre-defined cut-off should remain 3, with the possibility to personalise the threshold.

Changing prediction of mortality by systolic blood pressure with increasing age: the Rotterdam study.

There are indications that in persons of older age, systolic blood pressure (SBP) is no longer associated with mortality. This raises the question whether the predictive value of SBP changes from younger to older age groups. Analysis in the Rotterdam Study, a population-based prospective cohort study among 4,612 participants aged ≥55 years without previous cardiovascular disease and with a median follow-up of 14.9 (interquartile range, 11.1-15.8) years. Within four age groups (55-64, 65-74, 75-84, ≥85 years), the predictive value of baseline SBP for mortality was studied. From age 55 to ≥85 years, risk of all-cause mortality associated with SBP ≥160 mmHg decreased from HR 1.7 (95%CI 1.2-2.2) to HR 0.7 (95%CI 0.4-1.1), p for trend <0.001. For participants with SBP 140-159 mmHg, the risk decreased from HR 1.2 (95%CI 0.9-1.5) to HR 0.7 (95%CI 0.5-1.1), p for trend <0.001. Analyses in the 5-year age groups showed an increased risk with higher SBPs up to age 75 years. After 75 years, a trend towards SBP no longer being associated with an increased mortality risk was seen in our study. These findings need to be considered with recently reported beneficial effects of antihypertensive treatment in this age group.

[Cardiovascular prevention in the over-80 age group is not beneficial]. / Geen nut van cardiovasculaire preventie bij hoogbejaarden.

The high prevalence and incidence of cardiovascular disease in the oldest old justify consideration of both primary and secondary prevention measures in this age group. However, evidence for the effectiveness of any preventive intervention is lacking. Regarding primary prevention, it is also unknown which elderly are actually at risk of developing new cardiovascular disease.

Long-term use of proton pump inhibitors and vitamin B12 status in elderly individuals.

BACKGROUND: Some studies have shown that short-term use of proton pump inhibitors decreases the absorption of vitamin B12, but the results of studies into long-term proton pump inhibitor use and vitamin B12 deficiency are inconsistent. AIM: To investigate whether long-term proton pump inhibitor use is associated with an abnormal vitamin B12 status in elderly individuals. METHODS: One hundred and twenty-five long-term (>3, years) proton pump inhibitor users aged 65, years and above were recruited from general practices. Their 125 partners (who did not use proton pump inhibitors) served as the reference group. Vitamin B12 status was determined by serum levels of vitamin B12 and homocysteine, and mean corpuscular volume. RESULTS: No differences in mean vitamin B12 levels were observed between the long-term proton pump inhibitor users and their partners [345 (s.d. 126), pm vs. 339 (s.d. 133), pm, P, =, 0.73], even after adjustment for age, gender, Helicobacter pylori status and C-reactive protein levels (P, =, 0.87). Four proton pump inhibitor users and three partners had vitamin B12 levels <150, pm (3% vs. 2%, P, =, 1.00). No differences between the groups were observed in homocysteine levels and mean corpuscular volume. CONCLUSIONS: No association between long-term proton pump inhibitor use and vitamin B12 status was observed. Regular testing for low vitamin B12 levels in elderly patients on long-term treatment with proton pump inhibitors is therefore not recommended.

The mechanism of sevoflurane-induced cardioprotection is independent of the applied ischaemic stimulus in rat trabeculae.

BACKGROUND: Sevoflurane protects the myocardium against ischaemic injury through protein kinase C (PKC) activation, mitochondrial K+ATP-channel (mitoK+ATP) opening and production of reactive oxygen species (ROS). However, it is unclear whether the type of ischaemia determines the involvement of these signalling molecules. We therefore investigated whether hypoxia (HYP) or metabolic inhibition (MI), which differentially inhibit the mitochondrial electron transport chain (ETC), are comparable concerning the relative contribution of PKC, mitoK+ATP and ROS in sevoflurane-induced cardioprotection. METHODS: Rat right ventricular trabeculae were isolated and isometric contractile force (Fdev) was measured. Trabeculae were subjected to HYP (hypoxic glucose-free buffer; 40 min) or MI (glucose-free buffer, 2 mM cyanide; 30 min), followed by 60 min recovery (60 min). Contractile recovery (Fdev,rec) was determined at the end of the recovery period and expressed as a percentage of Fdev before hypoxia or MI, respectively. Chelerythrine (CHEL; 6 microM), 5-hydroxydecanoic acid sodium (100 microM) and n-(2-mercaptopropionyl)-glycine (MGP; 300 microM) were used to inhibit PKC, mitoK+ATP and ROS, respectively. RESULTS: Fdev,rec after HYP was reduced to 47 (3)% (P<0.001 vs control; n=5) whereas MI reduced Fdev,rec to 28 (5)% (P<0.001 vs control; n=5). A 15 min period of preconditioning with sevoflurane (3.8%) equally increased contractile recovery after HYP [76 (9)%; P<0.05 vs HYP] and MI [67 (8)%; P<0.01 vs MI]. Chelerythrine, 5-hydroxydecanoate and n-(2-mercaptopropionyl)-glycine abolished the protective effect of sevoflurane in both ischaemic models. Trabeculae subjected to HYP or MI did not demonstrate any increased apoptotic or necrotic markers. CONCLUSIONS: PKC, mitoK+ATP and ROS are involved in sevoflurane-induced cardioprotection after HYP or MI, suggesting that the means of mitochondrial ETC inhibition does not determine the signal transduction pathway for cardioprotection by anaesthetics.

Observation of the energy-level structure of the low-light adapted B800 LH4 complex by single-molecule spectroscopy.

Low-light adapted B800 light-harvesting complex 4 (LH4) from Rhodopseudomonas palustris is a complex in which the arrangement of the bacteriochloropyll a pigments is very different from the well-known B800-850 LH2 complex. For bulk samples, the main spectroscopic feature in the near-infrared is the occurrence of a single absorption band at 802 nm. Single-molecule spectroscopy can resolve the narrow bands that are associated with the exciton states of the individual complexes. The low temperature (1.2 K) fluorescence excitation spectra of individual LH4 complexes are very heterogeneous and display unique features. It is shown that an exciton model can adequately reproduce the polarization behavior of the complex, the experimental distributions of the number of observed peaks per complex, and the widths of the absorption bands. The results indicate that the excited states are mainly localized on one or a few subunits of the complex and provide further evidence supporting the recently proposed structure model.

Phosphatidylcholine association increases the anti-inflammatory and analgesic activity of ibuprofen in acute and chronic rodent models of joint inflammation: relationship to alterations in bioavailability and cyclooxygenase-inhibitory potency.

We investigated whether chemical association of phosphatidylcholine (PC) to ibuprofen enhances the anti-inflammatory/analgesic activity of the nonsteroidal anti-inflammatory drug (NSAID) and whether any change in therapeutic action is due to alterations in drug bioavailability and cyclooxygenase (COX) inhibitory activity. Acute/chronic joint inflammation was induced in rats, by injection of Complete Freund's Adjuvant. In the acute study, rats were administered saline, ibuprofen, or PC-ibuprofen (at NSAID doses of 10, 25, and 50 mg/kg), and 2 h later the pain threshold of the affected joint to pressure was measured. PC-ibuprofen increased the pain threshold at all NSAID doses, whereas unmodified ibuprofen demonstrated analgesic activity at only the highest dose. In the chronic study, we investigated the effects of saline, PC-ibuprofen, and ibuprofen (administered at 15 and 25 mg/kg/day) on ankle thickness and pain threshold, and demonstrated that PC-ibuprofen had significantly greater anti-inflammatory and analgesic activity than ibuprofen, over a 30- to 60-day period. PC association resulted in reduced uptake (decreased Cmax), a modest increase in the area under the curve, and a longer t(1/2) of ibuprofen. We also demonstrated that PC-ibuprofen was a comparable or a more effective inhibitor of both 6-keto-prostaglandin F1alpha concentration of fluid collected from tissue in and around the inflamed stifle joint, and COX-2 activity in activated human umbilical vein endothelial cells. In conclusion, we have demonstrated that PC association results in increases in ibuprofen's anti-inflammatory and analgesic activity in rodent models of acute and chronic joint inflammation, and this effect may relate to alterations in drug bioavailability and COX-inhibitory potency.

The differential effect of propofol on contractility of isolated myocardial trabeculae of rat and guinea-pig.

1. The effects of propofol on myocardial contractility were studied in rat, in which the contractile activation mainly depends on calcium derived from the sarcoplasmic reticulum (SR), and guinea-pig, in which transsarcolemmal influx of calcium plays a major role. 2. Intact and chemically skinned trabeculae from the right ventricle were studied. Intact trabeculae were electrically stimulated and force development during steady state and post rest contractions was measured. In saponin skinned trabeculae Ca(2+) uptake and release by the SR was studied. In Triton skinned trabeculae the influence of propofol on calcium sensitivity of the myofilaments was studied. 3. In intact rat trabeculae propofol in concentrations of 28, 112 and 280 microM did not change peak force development nor the pattern of post rest contraction. In guinea-pig trabeculae propofol significantly reduced peak force to respectively 64, 40 and 23% of control values and the post rest contractions were potentiated. In skinned trabeculae propofol did not affect Ca(2+) handling by the SR, nor did it change force production and Ca(2+) sensitivity of the myofilaments. 4. This study shows that, in contrast to rat, in guinea-pig propofol directly depresses myocardial contractility, probably by decreasing transsarcolemmal Ca(2+) influx. There is no significant influence of propofol on Ca(2+) handling by the SR, nor on the contractile proteins.

Toward fully automated high-resolution electron tomography.

Electron tomography is a powerful tool in elucidating the three-dimensional architecture of large biological complexes and subcellular organelles. Its use can be expanded through the simplification of the tomographic procedure by automation of its tasks. In this paper, we describe our EMACT/EMCAT system, which automates both tomographic data collection and reconstruction.