INCIDENCE, RISK FACTORS, AND OUTCOME OF SUSPECTED CENTRAL VENOUS CATHETER-RELATED INFECTIONS IN CRITICALLY ILL COVID-19 PATIENTS: A MULTICENTER RETROSPECTIVE COHORT STUDY

ABSTRACT

Background: Aims of this study were to investigate the prevalence and incidence of catheter-related infection, identify risk factors, and determine the relation of catheter-related infection with mortality in critically ill COVID-19 patients. Methods: This was a retrospective cohort study of central venous catheters (CVCs) in critically ill COVID-19 patients. Eligible CVC insertions required an indwelling time of at least 48 hours and were identified using a full-admission electronic health record database. Risk factors were identified using logistic regression. Differences in survival rates at day 28 of follow-up were assessed using a log-rank test and proportional hazard model. Results: In 538 patients, a total of 914 CVCs were included. Prevalence and incidence of suspected catheter-related infection were 7.9% and 9.4 infections per 1,000 catheter indwelling days, respectively. Prone ventilation for more than 5 days was associated with increased risk of suspected catheter-related infection; odds ratio, 5.05 (95% confidence interval 2.12-11.0). Risk of death was significantly higher in patients with suspected catheter-related infection (hazard ratio, 1.78; 95% confidence interval, 1.25-2.53). Conclusions: This study shows that in critically ill patients with COVID-19, prevalence and incidence of suspected catheter-related infection are high, prone ventilation is a risk factor, and mortality is higher in case of catheter-related infection.

Predicting responders to prone positioning in mechanically ventilated patients with COVID-19 using machine learning

Background

For mechanically ventilated critically ill COVID-19 patients, prone positioning has quickly become an important treatment strategy, however, prone positioning is labor intensive and comes with potential adverse effects. Therefore, identifying which critically ill intubated COVID-19 patients will benefit may help allocate labor resources.

Methods

From the multi-center Dutch Data Warehouse of COVID-19 ICU patients from 25 hospitals, we selected all 3619 episodes of prone positioning in 1142 invasively mechanically ventilated patients. We excluded episodes longer than 24 h. Berlin ARDS criteria were not formally documented. We used supervised machine learning algorithms Logistic Regression, Random Forest, Naive Bayes, K-Nearest Neighbors, Support Vector Machine and Extreme Gradient Boosting on readily available and clinically relevant features to predict success of prone positioning after 4 h (window of 1 to 7 h) based on various possible outcomes. These outcomes were defined as improvements of at least 10% in PaO₂/FiO₂ ratio, ventilatory ratio, respiratory system compliance, or mechanical power. Separate models were created for each of these outcomes. Re-supination within 4 h after pronation was labeled as failure. We also developed models using a 20 mmHg improvement cut-off for PaO₂/FiO₂ ratio and using a combined outcome parameter. For all models, we evaluated feature importance expressed as contribution to predictive performance based on their relative ranking.

Results

The median duration of prone episodes was 17 h (11–20, median and IQR, N = 2632). Despite extensive modeling using a plethora of machine learning techniques and a large number of potentially clinically relevant features, discrimination between responders and non-responders remained poor with an area under the receiver operator characteristic curve of 0.62 for PaO₂/FiO₂ ratio using Logistic Regression, Random Forest and XGBoost. Feature importance was inconsistent between models for different outcomes. Notably, not even being a previous responder to prone positioning, or PEEP-levels before prone positioning, provided any meaningful contribution to predicting a successful next proning episode.

Conclusions

In mechanically ventilated COVID-19 patients, predicting the success of prone positioning using clinically relevant and readily available parameters from electronic health records is currently not feasible. Given the current evidence base, a liberal approach to proning in all patients with severe COVID-19 ARDS is therefore justified and in particular regardless of previous results of proning.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13613-022-01070-0.

Assess and validate predictive performance of models for in-hospital mortality in COVID-19 patients: A retrospective cohort study in the Netherlands comparing the value of registry data with high-granular electronic health records

PURPOSE

To assess, validate and compare the predictive performance of models for in-hospital mortality of COVID-19 patients admitted to the intensive care unit (ICU) over two different waves of infections. Our models were built with high-granular Electronic Health Records (EHR) data versus less-granular registry data.

METHODS

Observational study of all COVID-19 patients admitted to 19 Dutch ICUs participating in both the national quality registry National Intensive Care Evaluation (NICE) and the EHR-based Dutch Data Warehouse (hereafter EHR). Multiple models were developed on data from the first 24 h of ICU admissions from February to June 2020 (first COVID-19 wave) and validated on prospective patients admitted to the same ICUs between July and December 2020 (second COVID-19 wave). We assessed model discrimination, calibration, and the degree of relatedness between development and validation population. Coefficients were used to identify relevant risk factors.

RESULTS

A total of 1533 patients from the EHR and 1563 from the registry were included. With high granular EHR data, the average AUROC was 0.69 (standard deviation of 0.05) for the internal validation, and the AUROC was 0.75 for the temporal validation. The registry model achieved an average AUROC of 0.76 (standard deviation of 0.05) in the internal validation and 0.77 in the temporal validation. In the EHR data, age, and respiratory-system related variables were the most important risk factors identified. In the NICE registry data, age and chronic respiratory insufficiency were the most important risk factors.

CONCLUSION

In our study, prognostic models built on less-granular but readily-available registry data had similar performance to models built on high-granular EHR data and showed similar transportability to a prospective COVID-19 population. Future research is needed to verify whether this finding can be confirmed for upcoming waves.

Predictors for extubation failure in COVID-19 patients using a machine learning approach

INTRODUCTION

Determining the optimal timing for extubation can be challenging in the intensive care. In this study, we aim to identify predictors for extubation failure in critically ill patients with COVID-19.

METHODS

We used highly granular data from 3464 adult critically ill COVID patients in the multicenter Dutch Data Warehouse, including demographics, clinical observations, medications, fluid balance, laboratory values, vital signs, and data from life support devices. All intubated patients with at least one extubation attempt were eligible for analysis. Transferred patients, patients admitted for less than 24 h, and patients still admitted at the time of data extraction were excluded. Potential predictors were selected by a team of intensive care physicians. The primary and secondary outcomes were extubation without reintubation or death within the next 7 days and within 48 h, respectively. We trained and validated multiple machine learning algorithms using fivefold nested cross-validation. Predictor importance was estimated using Shapley additive explanations, while cutoff values for the relative probability of failed extubation were estimated through partial dependence plots.

RESULTS

A total of 883 patients were included in the model derivation. The reintubation rate was 13.4% within 48 h and 18.9% at day 7, with a mortality rate of 0.6% and 1.0% respectively. The grandient-boost model performed best (area under the curve of 0.70) and was used to calculate predictor importance. Ventilatory characteristics and settings were the most important predictors. More specifically, a controlled mode duration longer than 4 days, a last fraction of inspired oxygen higher than 35%, a mean tidal volume per kg ideal body weight above 8 ml/kg in the day before extubation, and a shorter duration in assisted mode (< 2 days) compared to their median values. Additionally, a higher C-reactive protein and leukocyte count, a lower thrombocyte count, a lower Glasgow coma scale and a lower body mass index compared to their medians were associated with extubation failure.

CONCLUSION

The most important predictors for extubation failure in critically ill COVID-19 patients include ventilatory settings, inflammatory parameters, neurological status, and body mass index. These predictors should therefore be routinely captured in electronic health records.

The Dutch Data Warehouse, a multicenter and full-admission electronic health records database for critically ill COVID-19 patients

BACKGROUND

The Coronavirus disease 2019 (COVID-19) pandemic has underlined the urgent need for reliable, multicenter, and full-admission intensive care data to advance our understanding of the course of the disease and investigate potential treatment strategies. In this study, we present the Dutch Data Warehouse (DDW), the first multicenter electronic health record (EHR) database with full-admission data from critically ill COVID-19 patients.

METHODS

A nation-wide data sharing collaboration was launched at the beginning of the pandemic in March 2020. All hospitals in the Netherlands were asked to participate and share pseudonymized EHR data from adult critically ill COVID-19 patients. Data included patient demographics, clinical observations, administered medication, laboratory determinations, and data from vital sign monitors and life support devices. Data sharing agreements were signed with participating hospitals before any data transfers took place. Data were extracted from the local EHRs with prespecified queries and combined into a staging dataset through an extract-transform-load (ETL) pipeline. In the consecutive processing pipeline, data were mapped to a common concept vocabulary and enriched with derived concepts. Data validation was a continuous process throughout the project. All participating hospitals have access to the DDW. Within legal and ethical boundaries, data are available to clinicians and researchers.

RESULTS

Out of the 81 intensive care units in the Netherlands, 66 participated in the collaboration, 47 have signed the data sharing agreement, and 35 have shared their data. Data from 25 hospitals have passed through the ETL and processing pipeline. Currently, 3464 patients are included in the DDW, both from wave 1 and wave 2 in the Netherlands. More than 200 million clinical data points are available. Overall ICU mortality was 24.4%. Respiratory and hemodynamic parameters were most frequently measured throughout a patient's stay. For each patient, all administered medication and their daily fluid balance were available. Missing data are reported for each descriptive.

CONCLUSIONS

In this study, we show that EHR data from critically ill COVID-19 patients may be lawfully collected and can be combined into a data warehouse. These initiatives are indispensable to advance medical data science in the field of intensive care medicine.

Cerebral oxygenation responses to standing in elderly patients with predominantly diastolic dysfunction

Patients with left ventricular dysfunction may have different orthostatic responses of blood pressure (BP) and cerebral oxygenation than healthy elderly subjects. We investigated orthostatic changes in systemic haemodynamic variables and cerebral oxygenation in 21 elderly patients with heart failure New York Heart Association class I-III in stable condition (age 70-83 years) after withdrawal of furosemide and captopril for 2 weeks, and in 18 healthy elderly subjects (age 70-84 years). Frontal cortical concentration changes of oxyhaemoglobin ([O2Hb]) and deoxyhaemoglobin ([HHb]) were continuously measured by near-infrared spectrophotometry and BP changes by Finapres before and during 10 min of standing. Upon standing [O2Hb] reflecting blood flow, changed by -1.2 +/- 0.9 micromol L-1 (mean +/- SEM) in the patients, whereas it decreased by -4.5 +/- 0.6 micromol L-1 (P<0.01) in the healthy subjects after standing (P<0.05 between groups). [HHb] reflecting the sum of cerebral blood flow, arterial oxygen saturation and cerebral oxygen uptake, increased by 1.5 +/- 0.5 micromol L-1 (P<0.05) and 1.7 +/- 0.6 micromol L-1 (P<0.05), respectively. Compared with healthy elderly subjects, elderly patients with left ventricular dysfunction showed smaller orthostatic [O2Hb] decreases (P<0.01), in relation to higher orthostatic BP rises (P<0.05). These findings indicate that BP changes and an altered cardiovascular balance may influence orthostatic cortical haemodynamic responses in elderly subjects.

Effects of furosemide versus captopril on postprandial and orthostatic blood pressure and on cerebral oxygenation in patients > or = 70 years of age with heart failure

Elderly patients with heart failure are at risk of postprandial hypotension (PPH), orthostatic hypotension (OH), and concomitant cerebral oxygenation changes because of altered cardiovascular balance and the use of cardiovascular medications, such as furosemide and captopril. In 24 patients with heart failure (New York Heart Association class II to III, in stable condition, and receiving cardiovascular medication [aged 70 to 83 years]), blood pressure (BP) was measured by Finapres, and cortical concentrations of oxyhemoglobin and deoxyhemoglobin were measured using near-infrared spectroscopy during standing and after a 292-kcal carbohydrate meal. Tests were performed before and during therapy with furosemide 40 mg once daily (n = 11) or captopril 6.25 and 12.5 mg twice daily (n = 13) in a double-blind randomized trial. Before treatment, 13 of 24 patients had PPH, and 2 of 24 patients had OH. The first dose of furosemide significantly decreased postprandial systolic BP (p <0.05) and postprandial frontal cortical oxygenation (p <0.05), whereas the first dose of captopril did not. Furosemide and captopril did not significantly affect postprandial or orthostatic BP or cortical oxygenation after 2 weeks of treatment. Thus, PPH is a common phenomenon in elderly patients with heart failure, whereas OH is not. The first dose of furosemide 40 mg decreased postprandial systolic BP and frontal cortical oxygenation, in contrast with the first dose of captopril 6.25 mg and 2-week treatment with furosemide 40 mg once daily or captopril 12.5 mg twice daily. These findings indicate that initiating furosemide treatment worsens PPH, and furosemide is less safe in elderly patients with heart failure.

Simultaneous measurements of cerebral oxygenation changes during brain activation by near-infrared spectroscopy and functional magnetic resonance imaging in healthy young and elderly subjects

Near infrared spectroscopy (NIRS) and functional magnetic resonance imaging (fMRI) both allow non-invasive monitoring of cerebral cortical oxygenation responses to various stimuli. To compare these methods in elderly subjects and to determine the effect of age on cortical oxygenation responses, we determined motor-task-related changes in deoxyhemoglobin concentration ([HHb]) over the left motor cortex in six healthy young subjects (age 35 +/- 9 years, mean +/- SD) and five healthy elderly subjects (age 73 +/- 3 years) by NIRS and blood-oxygen-level-dependent (BOLD) fMRI simultaneously. The motor-task consisted of seven cycles of 20-sec periods of contralateral finger-tapping at a rate as fast as possible alternated with 40-sec periods of rest. Time-locked averages over the seven cycles were used for further analysis. Task-related decreases in [HHb] over the motor cortex were measured by NIRS, with maximum changes of -0.83 +/- 0.38 mumol/L (P < 0.01) for the young and -0.32 +/- 0.17 mumol/L (P < 0.05) for the elderly subjects. The BOLD-fMRI signal increased over the cortex volume under investigation with NIRS, with maximum changes of 2.11 +/- 0.72% (P < 0.01) for the young and 1.75 +/- 0.71% (P < 0.01) for the elderly subjects. NIRS and BOLD-fMRI measurements showed good correlation in the young (r = -0.70, r(2) = 0.48, P < 0.001) and elderly subjects (r = -0.82, r(2) = 0.67, P < 0.001). Additionally, NIRS measurements demonstrated age-dependent decreases in task-related cerebral oxygenation responses (P < 0.05), whereas fMRI measurements demonstrated smaller areas of cortical activation in the elderly subjects (P < 0.05). These findings demonstrate that NIRS and fMRI similarly assess cortical oxygenation changes in young subjects and also in elderly subjects. In addition, cortical oxygenation responses to brain activation alter with aging.

Effect of levodopa on orthostatic and postprandial hypotension in elderly Parkinsonian patients

BACKGROUND

This study describes orthostatic and postprandial hypotension in elderly Parkinsonian patients and evaluates the effect of levodopa therapy on orthostatic and postprandial hypotension in these patients.

METHODS

Seventeen elderly patients with a clinical diagnosis of Parkinson's disease or Parkinsonism based on the U.K. Parkinson's Disease Society Brain Bank criteria (age range, 66-84 years) participated in the study. Blood pressure was continuously monitored during standardized standing and meal tests, after starting 125-mg b.i.d. doses of levodopa/benserazide (Madopar) or placebo, in a double-blind, randomized, cross-over design. Seventeen age- and sex-matched healthy subjects served as controls.

RESULTS

Orthostatic hypotension was infrequently found in Parkinsonian patients (13%) and healthy subjects (6%; p =.58, between groups), whereas postprandial hypotension was more frequent in Parkinsonian patients (82%) than in healthy subjects (41%; p <.05, between groups). Doses of levodopa/benserazide, administered 2 times per day, did not result in significantly larger blood pressure decreases after standing or eating, or in higher frequencies of orthostatic or postprandial hypotension in the Parkinsonian group. Postprandial hypotension was related to disease severity (r = -.56, p <.05).

CONCLUSIONS

Postprandial hypotension, but not orthostatic hypotension, was more common in elderly Parkinsonian patients than in healthy subjects. Therapy with 125-mg b.i.d. doses of levodopa/benserazide did not significantly aggravate orthostatic or postprandial hypotension.

The influence of low-, normal-, and high-carbohydrate meals on blood pressure in elderly patients with postprandial hypotension

BACKGROUND

Postprandial hypotension (PPH) is a common and serious disorder of blood pressure (BP) regulation in elderly people. It has been suggested that primarily the carbohydrate (CH) content of a meal induces the BP decrease. Therefore, we examined the relationship between the CH content of meals and postprandial BP responses in elderly patients diagnosed with PPH.

METHODS

Twelve geriatric patients (aged 75 to 91 years; 6 men) who were previously diagnosed with PPH received standardized liquid meals with low- (25 g), normal- (65 g), and high- (125 g) CH content in random order on three separate days. Systolic BP (SBP), diastolic BP, and heart rate were measured every 5 minutes from 20 minutes before until 75 minutes after each meal. Postprandial symptoms were recorded every 15 minutes.

RESULTS

The maximum decrease in SBP was significantly smaller after the low-CH meal (-28 +/- 5 mm Hg) than after the normal- (-39 +/- 7 mm Hg) and high-CH meals (-40 +/- 5 mm Hg) (p <.050 between groups). In addition, the duration of PPH was significantly shorter (p <.010), and postprandial symptoms were less frequent and less severe after the low-CH meal.

CONCLUSIONS

Reducing the CH amount in meals induces significantly smaller decreases in SBP, shorter duration of PPH, and reduction of PPH-related symptoms. Therefore, limiting the CH content of an elderly patient's meal can be a clinically effective nonpharmacological treatment for PPH in elderly patients and can reduce the risk of developing symptomatic PPH.

Reproducibility of orthostatic changes in cerebral oxygenation in healthy subjects aged 70 years or older

In the elderly, standing can frequently be accompanied by blood pressure (BP) changes and cerebral symptoms such as dizziness, fall, or even syncope, but this may vary from day-to-day. Therefore, we aimed to investigate the reproducibility of orthostatic responses of cerebral cortical oxygenation and systemic haemodynamics in elderly subjects. In 27 healthy elderly subjects (age 70-84 years), changes in systolic BP (SBP), diastolic BP (DBP), heart rate (HR) and stroke volume (SV) were continuously monitored by Finapres (Finger Arterial Pressure), and changes in oxyhaemoglobin ([O2Hb]) and deoxyhaemoglobin ([HHb]) concentrations were continuously measured over the right frontal cortex by near infrared spectroscopy (NIRS) during supine rest and 10 min of active standing on two separate occasions. SBP and DBP increased by 6.7 +/- 15.4 mmHg (P<0.05, mean +/- SD) and 8.2 +/- 6.4 mmHg (P<0.01), respectively, whereas HR increased by 9.5 +/- 5.0 bpm (P<0.01) and SV decreased by -8.3 +/- 7.4 ml (P<0.01) during standing on the first occasion. [O2Hb] decreased by -3.9 +/- 2.9 micromol l-1 (P<0.01), while [HHb] increased by 1.8 +/- 2.2 micromol l-1 (P<0.01). Group-averaged orthostatic changes in cortical oxygenation and systemic haemodynamics were very similar on the two occasions, although an intraindividual variation was found. Cortical oxygenation changes were not accompanied by severe cerebral symptoms. Active standing induced reproducible group-averaged frontal cortical oxygenation declines in healthy elderly subjects, although an intraindividual day-to-day variability was present, possibly related to the variability of orthostatic BP responses. These findings indicate that cerebral autoregulation fails to compensate completely for postural changes in elderly subjects, which might predispose elderly subjects to ischaemic cerebral symptoms.

Achieving haemodynamic baseline values with Finapres in elderly subjects during supine rest

BACKGROUND

Clear guidelines for the resting time necessary to achieve stable blood pressure (BP) levels are scant in gerontology research. Therefore, we aimed to determine the minimum period required for obtaining haemodynamic baseline values in elderly subjects during supine rest. In addition, we evaluated the effect of cardiovascular morbidity, such as diastolic heart failure, and the effect of complex comorbidity of geriatric patients, on haemodynamic changes during supine rest.

METHODS

A total of 17 healthy subjects, 18 heart failure patients with normal systolic function and 24 geriatric patients, aged 70 years and more, participated. After an overnight fast, changes in systolic BP (SBP), diastolic BP (DBP), heart rate (HR), and stroke volume (SV) were determined by Finapres beat-to-beat non-invasive BP monitoring during a 20-min supine rest. The procedure was repeated in the healthy subjects and geriatric patients on a second day.

RESULTS

Complete BP stabilization was reached in each group within 5 min of supine rest, as SBP remained essentially unchanged and DBP did not change significantly anymore after the fourth minute. In the heart failure patients, HR decreased and SV increased until the twelfth minute of rest. The SBP, DBP, HR, and SV changes during supine rest showed good reproducibility.

CONCLUSIONS

A span of 5 min of supine rest ensured achievement of reliable and reproducible baseline BP values by Finapres in elderly subjects. However, we recommend at least 12 min of rest to obtain full haemodynamic stability in elderly patients with diminished cardiac compliance and diastolic function.

Sympathoadrenal activation and the dumping syndrome after gastric surgery

Dumping symptoms suggest concomitant sympathoadrenal activation. To evaluate the relation between dumping symptoms and postprandial plasma catecholamine changes, standardized dumping-provocation tests with use of oral glucose were performed for 16 gastric surgery patients with dumping, for 14 gastric surgery patients without dumping, and for 14 healthy control patients. Early dumping symptoms were present for all patients with dumping, and late symptoms developed in three patients with dumping after glucose ingestion. Patients without dumping and healthy control patients had slight complaints or no complaints. Systolic and diastolic blood pressure remained unaffected for the three groups. Positive breath-hydrogen tests, heart rate increments, and reactive plasma glucose decrements were present for patients with dumping and for patients without dumping, but not for control patients. Plasma noradrenaline and adrenaline increased for patients with dumping and for patients without dumping, but not for control patients. The noradrenaline increment was higher for patients with dumping (98%) than for patients without dumping (78%; p <0.05). The noradrenaline increment was related to the dumping score and to the heart rate increment for the first hour after glucose ingestion, whereas the adrenaline increment was related to the plasma glucose decrement for the third hour. Therefore, dumping symptoms clearly are accompanied by postprandial sympathoadrenal activation, but sympathoadrenal activation cannot account completely for development of dumping symptoms.

Cerebral oxygenation declines in healthy elderly subjects in response to assuming the upright position

BACKGROUND AND PURPOSE

With increasing age, assuming the upright position is more often accompanied by symptoms such as dizziness and lightheadedness, possibly as a result of a diminished oxygen supply to the brain due to impaired cerebral autoregulation. We aimed to quantify postural changes in cerebral oxygenation and systemic hemodynamics in healthy elderly and young subjects.

METHODS

In 18 healthy elderly subjects (aged 70 to 83 years) and 10 healthy young subjects (aged 22 to 45 years), frontal cortical oxygenation and hemodynamic responses were continuously monitored by near infrared spectroscopy and Finapres, respectively, before and during 10 minutes of active standing.

RESULTS

-Cortical oxyhemoglobin concentration [O(2)Hb] decreased by -4.6+/-2.2 micromol/L (P<0.001) and cortical deoxyhemoglobin concentration increased by 1.5+/-2.4 micromol/L (P<0.05) in the elderly subjects after posture change, whereas these variables did not change significantly in the young subjects. The postural hemodynamic changes tended to be attenuated in the elderly subjects, except for the increases in systolic blood pressure (BP). Smaller postural increases in diastolic BP were related to larger [O(2)Hb] decreases (r=0.53, P<0.01, corrected for the age effect).

CONCLUSIONS

Assuming the upright position evokes an asymptomatic decrease in frontal cortical oxygenation in healthy elderly subjects but not in healthy young subjects. Cortical [O(2)Hb] changes are affected by diastolic BP changes. These findings may indicate that regulation of cerebral oxygenation alters with increasing age.