Hydrocortisone plus fludrocortisone for community acquired pneumonia-related septic shock: a subgroup analysis of the APROCCHSS phase 3 randomised trial

BACKGROUND

Glucocorticoids probably improve outcomes in patients hospitalised for community acquired pneumonia (CAP). In this a priori planned exploratory subgroup analysis of the phase 3 randomised controlled Activated Protein C and Corticosteroids for Human Septic Shock (APROCCHSS) trial, we aimed to investigate responses to hydrocortisone plus fludrocortisone between CAP and non-CAP related septic shock.

METHODS

APROCCHSS was a randomised controlled trial that investigated the effects of hydrocortisone plus fludrocortisone, drotrecogin-alfa (activated), or both on mortality in septic shock in a two-by-two factorial design; after drotrecogin-alfa was withdrawn on October 2011, from the market, the trial continued on two parallel groups. It was conducted in 34 centres in France. In this subgroup study, patients with CAP were a preselected subgroup for an exploratory secondary analysis of the APROCCHSS trial of hydrocortisone plus fludrocortisone in septic shock. Adults with septic shock were randomised 1:1 to receive, in a double-blind manner, a 7-day treatment with daily administration of intravenous hydrocortisone 50 mg bolus every 6h and a tablet of 50 μg of fludrocortisone via the nasogastric tube, or their placebos. The primary outcome was 90-day all-cause mortality. Secondary outcomes included all-cause mortality at intensive care unit (ICU) and hospital discharge, 28-day and 180-day mortality, the number of days alive and free of vasopressors, mechanical ventilation, or organ failure, and ICU and hospital free-days to 90-days. Analysis was done in the intention-to-treat population. The trial was registered at ClinicalTrials.gov (NCT00625209).

FINDINGS

Of 1241 patients included in the APROCCHSS trial, CAP could not be ruled in or out in 31 patients, 562 had a diagnosis of CAP (279 in the placebo group and 283 in the corticosteroid group), and 648 patients did not have CAP (329 in the placebo group and 319 in the corticosteroid group). In patients with CAP, there were 109 (39%) deaths of 283 patients at day 90 with hydrocortisone plus fludrocortisone and 143 (51%) of 279 patients receiving placebo (odds ratio [OR] 0·60, 95% CI 0·43-0·83). In patients without CAP, there were 148 (46%) deaths of 319 patients at day 90 in the hydrocortisone and fludrocortisone group and 157 (48%) of 329 patients in the placebo group (OR 0·95, 95% CI 0·70-1·29). There was significant heterogeneity in corticosteroid effects on 90-day mortality across subgroups with CAP and without CAP (p=0·046 for both multiplicative and additive interaction tests; moderate credibility). Of 1241 patients included in the APROCCHSS trial, 648 (52%) had ARDS (328 in the placebo group and 320 in the corticosteroid group). There were 155 (48%) deaths of 320 patients at day 90 in the corticosteroid group and 186 (57%) of 328 patients in the placebo group. The OR for death at day 90 was 0·72 (95% CI 0·53-0·98) in patients with ARDS and 0·85 (0·61-1·20) in patients without ARDS (p=0·45 for multiplicative interaction and p=0·42 for additive interaction). The OR for observing at least one serious adverse event (corticosteroid group vs placebo) within 180 days post randomisation was 0·64 (95% CI 0·46-0·89) in the CAP subgroup and 1·02 (0·75-1·39) in the non-CAP subgroup (p=0·044 for multiplicative interaction and p=0·042 for additive interaction).

INTERPRETATION

In a pre-specified subgroup analysis of the APROCCHSS trial of patients with CAP and septic shock, hydrocortisone plus fludrocortisone reduced mortality as compared with placebo. Although a large proportion of patients with CAP also met criteria for ARDS, the subgroup analysis was underpowered to fully discriminate between ARDS and CAP modifying effects on mortality reduction with corticosteroids. There was no evidence of a significant treatment effect of corticosteroids in the non-CAP subgroup.

FUNDING

Programme Hospitalier de Recherche Clinique of the French Ministry of Health, by Programme d'Investissements d'Avenir, France 2030, and IAHU-ANR-0004.

Incidence and survival of transthyretin amyloid cardiomyopathy from a French nationwide study of in- and out-patient databases

BACKGROUND

Precise data about ATTR-CM incidence rates at national level are scarce. Consequently, this study aimed to estimate the annual incidence and survival of transthyretin amyloid cardiomyopathy (ATTR-CM) in France between 2011 and 2019 using real world data. We used the French nationwide exhaustive data (SNDS database) gathering in- and out-patient claims. As there is no specific ICD-10 marker code for ATTR-CM, diagnosis required both amyloidosis (identified by E85. ICD-10 code or a tafamidis meglumine delivery) and a cardiovascular condition (identified by ICD-10 or medical procedure codes related to either heart failure, arrhythmias, conduction disorders or cardiomyopathies), not necessarily reported at the same visit. Patients with probable AL-form of amyloidosis or probable AA-form of amyloidosis were excluded.

RESULTS

Between 2011 and 2019, 8,950 patients with incident ATTR-CM were identified. Incidence rates increased from 0.6 / 100,000 person-years in 2011 to 3.6 / 100,000 person-years in 2019 (p < 0.001), reaching 2377 new cases in 2019. Sex ratios (M/F) increased from 1.52 in 2011 to 2.23 in 2019. In 2019, median age at diagnosis was 84.0 years (85.5 for women and 83.5 for men). Median survival after diagnosis was 41.9 months (95% CI [39.6, 44.1]).

CONCLUSIONS

This is the first estimate of nationwide ATTR-CM incidence in France using comprehensive real-world databases. We observed an increased incidence over the study period, consistent with an improvement in ATTR-CM diagnosis in recent years.

Volume responsiveness revisited: an observational multicenter study of continuous versus binary outcomes combining echocardiography and venous return physiology

Echocardiography can assess cardiac preload when fluid administration is used to treat acute circulatory failure. Changes in stroke volume (SV) are inherently a continuous phenomenon relating to the pressure gradient for venous return (VRdP). However, most clinical studies have applied a binary definition based on a fractional change in SV. This study tested the hypothesis that calculating the analog mean systemic filling pressure (Pmsa) and VRdP would enhance echocardiography to describe SV responses to a preload challenge. We investigated 540 (379 males) patients during a standardized passive leg raising (PLR) maneuver. Patients were further categorized by the presence of impaired right ventricular function (impRV) or increased intra-abdominal hypertension (IAH). Multivariable linear regression identified VRdP (partial r = -0.26, P < 0.001), ventilatory-induced variations in superior vena cava diameter (partial r = 0.43, P < 0.001), and left ventricular outflow tract maximum-Doppler velocity (partial r = 0.13, P < 0.001) as independent variables associated with SV changes. The model explained 38% (P < 0.001) of the SV change in the whole cohort and 64% (P < 0.001) when excluding patients with impRV or IAH. The correlation between Pmsa or VRdP and SV changes lost statistical significance with increasing impRV or IAH. A binary definition of volume responsiveness (>10% increase in SV) generated an area under the curve of 0.79 (P < 0.001) in logistic regression but failed to identify Pmsa or VRdP as independent variables and overlooked the confounding influence of impRV and IAH. In conclusion, venous return physiology may enhance echocardiographic assessments of volume responsiveness, which should be based on continuous changes in stroke volume.NEW & NOTEWORTHY The analog mean systemic filling pressure and the pressure gradient for venous return combined with echocardiography predict continuous changes in stroke volume following a passive leg raising maneuver. The confounding effects of impaired right ventricular function and increased intra-abdominal pressure can be identified. Using a binary cutoff for the fractional change in stroke volume, common in previous clinical research, fails to identify the importance of variables relevant to venous return physiology and confounding conditions.

Mitral annular plane systolic excursion for assessing left ventricular systolic dysfunction in patients with septic shock

Background

Using easy-to-determine bedside measurements, we developed an echocardiographic algorithm for predicting left ventricular ejection fraction (LVEF) and longitudinal strain (LVLS) in patients with septic shock.

Methods

We measured septal and lateral mitral annular plane systolic excursion (MAPSE), septal and lateral mitral S-wave velocity, and the left ventricular longitudinal wall fractional shortening in patients with septic shock. We used a conditional inference tree method to build a stratification algorithm. The left ventricular systolic dysfunction was defined as an LVEF <50%, an LVLS greater than -17%, or both.

Results

We included 71 patients (males: 61%; mean [standard deviation] age: 61 [15] yr). Septal MAPSE (cut-off: 1.2 cm) was the best predictor of left ventricular systolic dysfunction. The level of agreement between the septal MAPSE and the left ventricular systolic dysfunction was 0.525 [0.299-0.751]. A septal MAPSE ≥1.2 cm predicted normal LVEF in 17/18 patients, or 94%. In contrast, a septal MAPSE <1.2 cm predicted left ventricular systolic dysfunction with impaired LVLS in 46/53 patients (87%), although 32/53 (60%) patients had a preserved LVEF.

Conclusions

Septal MAPSE is easily measured at the bedside and might help clinicians to detect left ventricular systolic dysfunction early-especially when myocardial strain measurements are not feasible.

Inhaled nitric oxide in patients with acute respiratory distress syndrome caused by COVID-19: treatment modalities, clinical response, and outcomes

BACKGROUND

Inhaled nitric oxide (iNO) has been widely used in patients with COVID-19-related acute respiratory distress syndrome (C-ARDS), though its physiological effects and outcome are debated in this setting. The objective of this cohort study was to describe the modalities of iNO use, clinical response, and outcomes in a large cohort of C-ARDS patients.

METHODS

Multicentre, retrospective cohort study conducted in France.

RESULTS

From end February to December 2020, 300 patients (22.3% female) were included, 84.5% were overweight and 69.0% had at least one comorbidity. At ICU admission, their median (IQR) age, SAPS II, and SOFA score were 66 (57-72) years, 37 (29-48), and 5 (3-8), respectively. Patients were all ventilated according to a protective ventilation strategy, and 68% were prone positioned before iNO initiation. At iNO initiation, 2%, 37%, and 61% of patients had mild, moderate, and severe ARDS, respectively. The median duration of iNO treatment was 2.8 (1.1-5.5) days with a median dosage of 10 (7-13) ppm at initiation. Responders (PaO₂/FiO₂ ratio improving by 20% or more) represented 45.7% of patients at 6 h from iNO initiation. The severity of ARDS was the only predictive factor associated with iNO response. Among all evaluable patients, the crude mortality was not significantly different between responders at 6 h and their counterparts. Of the 62 patients with refractory ARDS (who fulfilled extracorporeal membrane oxygenation criteria before iNO initiation), 32 (51.6%) no longer fulfilled these criteria after 6 h of iNO. The latter showed significantly lower mortality than the other half (who remained ECMO eligible), including after confounder adjustment (adjusted OR: 0.23, 95% CI 0.06, 0.89, p = 0.03).

CONCLUSIONS

Our study reports the benefits of iNO in improving arterial oxygenation in C-ARDS patients. This improvement seems more relevant in the most severe cases. In patients with ECMO criteria, an iNO-driven improvement in gas exchange was associated with better survival. These results must be confirmed in well-designed prospective studies.

Annexin-V positive extracellular vesicles level is increased in severe COVID-19 disease

Objectives

To evaluate extracellular vesicles levels in a cohort of SARS-CoV-2's patients hospitalized in an intensive care unit with and without COVID-19 associated thromboembolic events.

Methods

In this study, we aim to assess endothelial and platelet membrane-derived extracellular vesicles levels in a cohort of SARS-CoV-2 patients with and without COVID-19-associated thromboembolic events who were hospitalized in an intensive care unit. Annexin-V positive extracellular vesicles levels were prospectively assessed by flow cytometry in one hundred twenty-three critically ill adults diagnosed with acute respiratory distress syndrome associated with a SARS-CoV-2 infection, ten adults diagnosed for moderate SARS-CoV-2 infection and 25 healthy volunteers.

Results

On our critically ill patients, thirty-four patients (27.6%) had a thromboembolic event, Fifty-three (43%) died. Endothelial and platelet membrane-derived extracellular vesicles were drastically increased in SARS-CoV-2 patients hospitalized in the ICU compared to healthy volunteers. Moreover a slighty higher small/large ratio for platelets membrane-derived extracellular vesicles in patients was linked to thrombo-embolic events.

Conclusion

A comparison between total annexin-V positive extracellular vesicles levels in severe and moderate SARS-CoV-2 infection and healthy controls showed a significant increase in patients with severe infection and their sizes could be considered as biomarkers of SARS-CoV-2 associated thrombo-embolic events.

βeta blocker interruption after uncomplicated myocardial infarction: rationale and design of the randomized ABYSS trial

BACKGROUND

The long-term use of β-blocker after myocardial infarction (MI) when global left ventricular ejection fraction (LVEF) is preserved has not been studied in the era of modern myocardial reperfusion and secondary prevention therapies. It is unknown whether β-blockers are useful in stable post-MI patients without reduced LVEF and without heart failure.

METHODS

The Assessment of β-blocker interruption 1 Year after an uncomplicated myocardial infarction on Safety and Symptomatic cardiac events requiring hospitalization (ABYSS) Trial enrolled in 49 centers in France, 3,700 patients with a prior (>6 months) history of MI and a LVEF >40%, chronically treated with a β-blocker and without any major cardiovascular event (MACE) in the past 6 months. These patients were randomized to interruption or continuation of their β-blocker therapy. The primary objective is to demonstrate the noninferiority of interruption vs continuation of the β-blocker therapy on the primary composite endpoint of all-cause death, stroke, MI, hospitalization for any cardiovascular reason at the end of follow-up (accrual follow-up) with a one-year minimum follow-up for the last randomized patient. Secondary objectives will focus on patient reported outcomes with the evaluation of the quality of life before and after randomization with the EQ5D-5L questionnaire. Enrolment has been completed.

CONCLUSION

The ABYSS trial evaluates the cardiovascular safety of β-blocker interruption in stabilized post-MI patients without heart failure nor reduced LVEF. ABYSS trial is a reappraisal of β-blockers life-long therapy in stable post-MI patients without reduced LVEF.

CLINICAL TRIAL REGISTRATION

NCT03498066 (clinicaltrials.gov).

Cardiac function in critically ill patients with severe COVID: A prospective cross-sectional study in mechanically ventilated patients

PURPOSE

To evaluate cardiac function in mechanically ventilated patients with COVID-19.

MATERIALS AND METHODS

Prospective, cross-sectional multicenter study in four university-affiliated hospitals in Chile. All consecutive patients with COVID-19 ARDS requiring mechanical ventilation admitted between April and July 2020 were included. We performed systematic transthoracic echocardiography assessing right and left ventricular function within 24 h of intubation.

RESULTS

140 patients aged 57 ± 11, 29% female were included. Cardiac output was 5.1 L/min [IQR 4.5-6.2] and 86% of the patients required norepinephrine. ICU mortality was 29% (40 patients). Fifty-four patients (39%) exhibited right ventricle dilation out of whom 20 patients (14%) exhibited acute cor pulmonale (ACP). Eight out of the twenty patients with ACP exhibited pulmonary embolism (40%). Thirteen patients (9%) exhibited left ventricular systolic dysfunction (ejection fraction <45%). In the multivariate analysis acute cor pulmonale and PaO₂/FiO₂ ratio were independent predictors of ICU mortality.

CONCLUSIONS

Right ventricular dilation is highly prevalent in mechanically ventilated patients with COVID-19 ARDS. Acute cor pulmonale was associated with reduced pulmonary function and, in only 40% of patients, with co-existing pulmonary embolism. Acute cor pulmonale is an independent risk factor for ICU mortality.

Effect of RNAi therapeutics patisiran and vutrisiran on orthostatic hypotension due to dysautonomia in patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy

Background

Hereditary transthyretin-mediated (hATTR) amyloidosis, also known as ATTRv amyloidosis, is a rapidly progressive, multisystem disease. Orthostatic hypotension, due to autonomic neuropathy, is a common yet hard-to-treat disease manifestation in patients with hATTR amyloidosis. Fatigue, muscle weakness, and deterioration in cardiac function further exacerbate orthostatic symptoms. Efficacy of RNAi therapeutics patisiran and vutrisiran was assessed in patients with hATTR amyloidosis with polyneuropathy across the APOLLO (NCT01960348), Global Open-Label Extension (OLE) (NCT02510261), and HELIOS-A (NCT03759379) studies, respectively.

Purpose

Evaluate the quantitative effect of patisiran and vutrisiran on orthostatic hypotension in patients with hATTR amyloidosis with polyneuropathy.

Methods

In APOLLO, patients were randomised 2:1 to patisiran 0.3 mg/kg or placebo, IV q3w. Patients who completed APOLLO (APOLLO-placebo, APOLLO-patisiran) were eligible to enrol into the ongoing Global OLE (patisiran 0.3 mg/kg IV q3w). In HELIOS-A, patients were randomised 3:1 to vutrisiran (25 mg SC q3m) or patisiran (0.3 mg/kg IV q3w; reference group). Primary endpoint for APOLLO and HELIOS-A was change from baseline in the modified Neuropathy Impairment Score+7 (mNIS+7) vs APOLLO placebo at M18 (APOLLO) and M9 (HELIOS-A). Orthostatic hypotension was evaluated using the postural blood pressure (PBP) component of mNIS+7, calculated as the mean of 2 supine readings of systolic BP [SBP, mmHg] taken 15 min apart minus the lowest SBP upon standing at 1, 3, and 5 min. A smaller reduction in observed SBP between supine and upright readings indicated an improved PBP.

Results

APOLLO enrolled 225 patients (placebo, n=77; patisiran, n=148), Global OLE 211 and HELIOS-A 164 (vutrisiran, n=122; patisiran, n=42). At baseline, the severity of orthostatic hypotension was similar between within-study treatment arms in APOLLO and HELIOS-A. In APOLLO, patisiran-treated patients showed PBP improvement or stabilization from baseline to M18 (mean [SD] change in SBP: baseline, −17.6 [19.4]; M18, −13.5 [16.8]) and was maintained at Global OLE 36m (−13.4 [15.6]). In contrast, placebo-treated patients in APOLLO had an increased change in PBP over 18m (baseline, −17.5 [16.5]; M18, −20.4 [16.9]); their PBP improved after patisiran initiation (Global OLE 36m, −16.6 [18.1]). In HELIOS-A, stabilization in PBP was observed in the vutrisiran arm (baseline, −11.2 [14.0], M18, −11.7 [14.6]). In the smaller patisiran arm, while the change in PBP increased, the value remained in the normal range (baseline, −11.6 [17.2]; M18, −14.2 [15.5]). Patisiran and vutrisiran have acceptable safety profiles.

Conclusions

PBP analyses quantify the benefits of RNAi therapeutics patisiran and vutrisiran on autonomic function in patients with hATTR amyloidosis with polyneuropathy. The increase in change in PBP to a symptomatic range without treatment indicates the importance of early intervention.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Alnylam Pharmaceuticals

Echocardiography findings in COVID-19 patients admitted to intensive care units: a multi-national observational study (the ECHO-COVID study)

PURPOSE

Severely ill patients affected by coronavirus disease 2019 (COVID-19) develop circulatory failure. We aimed to report patterns of left and right ventricular dysfunction in the first echocardiography following admission to intensive care unit (ICU).

METHODS

Retrospective, descriptive study that collected echocardiographic and clinical information from severely ill COVID-19 patients admitted to 14 ICUs in 8 countries. Patients admitted to ICU who received at least one echocardiography between 1st February 2020 and 30th June 2021 were included. Clinical and echocardiographic data were uploaded using a secured web-based electronic database (REDCap).

RESULTS

Six hundred and seventy-seven patients were included and the first echo was performed 2 [1, 4] days after ICU admission. The median age was 65 [56, 73] years, and 71% were male. Left ventricle (LV) and/or right ventricle (RV) systolic dysfunction were found in 234 (34.5%) patients. 149 (22%) patients had LV systolic dysfunction (with or without RV dysfunction) without LV dilatation and no elevation in filling pressure. 152 (22.5%) had RV systolic dysfunction. In 517 patients with information on both paradoxical septal motion and quantitative RV size, 90 (17.4%) had acute cor pulmonale (ACP). ACP was associated with mechanical ventilation (OR > 4), pulmonary embolism (OR > 5) and increased PaCO₂. Exploratory analyses showed that patients with ACP and older age were more likely to die in hospital (including ICU).

CONCLUSION

Almost one-third of this cohort of critically ill COVID-19 patients exhibited abnormal LV and/or RV systolic function in their first echocardiography assessment. While LV systolic dysfunction appears similar to septic cardiomyopathy, RV systolic dysfunction was related to pressure overload due to positive pressure ventilation, hypercapnia and pulmonary embolism. ACP and age seemed to be associated with mortality in this cohort.

The Endothelium and COVID-19: An Increasingly Clear Link Brief Title: Endotheliopathy in COVID-19

The endothelium has a fundamental role in the cardiovascular complications of coronavirus disease 2019 (COVID-19). Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) particularly affects endothelial cells. The virus binds to the angiotensin-converting enzyme 2 (ACE-2) receptor (present on type 2 alveolar cells, bronchial epithelial cells, and endothelial cells), and induces a cytokine storm. The cytokines tumor necrosis factor alpha, interleukin-1 beta, and interleukin-6 have particular effects on endothelial cells-leading to endothelial dysfunction, endothelial cell death, changes in tight junctions, and vascular hyperpermeability. Under normal conditions, apoptotic endothelial cells are removed into the bloodstream. During COVID-19, however, endothelial cells are detached more rapidly, and do not regenerate as effectively as usual. The loss of the endothelium on the luminal surface abolishes all of the vascular responses mediated by the endothelium and nitric oxide production in particular, which results in greater contractility. Moreover, circulating endothelial cells infected with SARS-CoV-2 act as vectors for viral dissemination by forming clusters that migrate into the circulation and reach distant organs. The cell clusters and the endothelial dysfunction might contribute to the various thromboembolic pathologies observed in COVID-19 by inducing the formation of intravascular microthrombi, as well as by triggering disseminated intravascular coagulation. Here, we review the contributions of endotheliopathy and endothelial-cell-derived extracellular vesicles to the pathogenesis of COVID-19, and discuss therapeutic strategies that target the endothelium in patients with COVID-19.

Pathology Assessments of Multiple Organs in Fatal COVID-19 in Intensive Care Unit vs. Non-intensive Care Unit Patients

Purpose

The objective of the present study was to provide a detailed histopathological description of fatal coronavirus disease 2019 (COVID 19), and compare the lesions in Intensive Care Unit (ICU) and non-ICU patients.

Methods

In this prospective study we included adult patients who died in hospital after presenting with confirmed COVID-19. Multiorgan biopsies were performed. Data generated with light microscopy, transmission electron microscopy (TEM) and RT-PCR assays were reviewed.

Results

20 patients were enrolled in the study and the main pulmonary finding was alveolar damage, which was focal in 11 patients and diffuse in 8 patients. Chronic fibrotic and inflammatory lesions were observed in 18 cases, with acute inflammatory lesions in 12 cases. Diffuse lesions, collapsed alveoli and dystrophic pneumocytes were more frequent in the ICU group (62.5%, vs. 25%; 63%, vs. 55%; 87.5%, vs. 54%). Acute lesions (82%, vs. 37.5%; p = 0.07) with neutrophilic alveolitis (63.6% vs. 0%, respectively; p = 0.01) were observed more frequently in the non-ICU group. Viral RNA was detected in 12 lung biopsies (60%) up to 56 days after disease upset. TEM detected viral particles in the lung and kidney biopsy samples up to 27 days after disease upset. Furthermore, abundant networks of double-membrane vesicles (DMVs, a hallmark of viral replication) were observed in proximal tubular epithelial cells.

Conclusion

Lung injury was different in ICU and non-ICU patients. Extrapulmonary damage consisting in kidney and myocardial injury were more frequent in ICU patients. Our TEM experiments provided the first description of SARS-CoV-2-induced DMVs in kidney biopsy samples—a sign of intense viral replication in this organ.

Criteria, Processes, and Determination of Competence in Basic Critical Care Echocardiography Training: A Delphi Process Consensus Statement by the Learning Ultrasound in Critical Care (LUCC) Initiative

BACKGROUND

With the paucity of high-quality studies on longitudinal basic critical care echocardiography (BCCE) training, expert opinion guidelines have guided BCCE competence educational standards and processes. However, existing guidelines lack precise detail due to methodological flaws during guideline development.

RESEARCH QUESTIONS

To formulate methodologically robust guidelines on BCCE training using evidence and expert opinion, detailing specific criteria for every step, we conducted a modified Delphi process using the principles of the validated AGREE-II tool. Based on systematic reviews, the following domains were chosen: components of a longitudinal BCCE curriculum; pass-grade criteria for image-acquisition and image-interpretation; and formative/summative assessment and final competence processes.

STUDY DESIGN AND METHODS

Between April 2020 and May 2021, a total of 21 BCCE experts participated in four rounds. Rounds 1 and 2 used five web-based questionnaires, including branching-logic software for directed questions to individual panelists. In round 3 (videoconference), the panel finalized the recommendations by vote. During the journal peer-review process, Round 4 was conducted as Web-based questionnaires. Following each round, the agreement threshold for each item was determined as ≥ 80% for item inclusion and ≤ 30% for item exclusion.

RESULTS

Following rounds 1 and 2, agreement was reached on 62 of 114 items. To the 49 unresolved items, 12 additional items were added in round 3, with 56 reaching agreement and five items remaining unresolved. There was agreement that longitudinal BCCE training must include introductory training, mentored formative training, summative assessment for competence, and final cognitive assessment. Items requiring multiple rounds included two-dimensional views, Doppler, cardiac output, M-mode measurement, minimum scan numbers, and pass-grade criteria. Regarding objective criteria for image-acquisition and image-interpretation quality, the panel agreed on maintaining the same criteria for formative and summative assessment, to categorize BCCE findings as major vs minor and a standardized approach to errors, criteria for readiness for summative assessment, and supervisory options.

INTERPRETATION

In conclusion, this expert consensus statement presents comprehensive evidence-based recommendations on longitudinal BCCE training. However, these recommendations require prospective validation.

Respiratory effects of lung recruitment maneuvers depend on the recruitment-to-inflation ratio in patients with COVID-19-related acute respiratory distress syndrome

Background

In the context of acute respiratory distress syndrome (ARDS), the response to lung recruitment maneuvers (LRMs) varies considerably from one patient to another and so is difficult to predict. The aim of the study was to determine whether or not the recruitment-to-inflation (R/I) ratio could differentiate between patients according to the change in lung mechanics during the LRM.

Methods

We evaluated the changes in gas exchange and respiratory mechanics induced by a stepwise LRM at a constant driving pressure of 15 cmH₂O during pressure-controlled ventilation. We assessed lung recruitability by measuring the R/I ratio. Patients were dichotomized with regard to the median R/I ratio.

Results

We included 30 patients with moderate-to-severe ARDS and a median [interquartile range] R/I ratio of 0.62 [0.42–0.83]. After the LRM, patients with high recruitability (R/I ratio ≥ 0.62) presented an improvement in the P_aO₂/F_iO₂ ratio, due to significant increase in respiratory system compliance (33 [27–42] vs. 42 [35–60] mL/cmH₂O; p < 0.001). In low recruitability patients (R/I < 0.62), the increase in P_aO₂/F_iO₂ ratio was associated with a significant decrease in pulse pressure as a surrogate of cardiac output (70 [55–85] vs. 50 [51–67] mmHg; p = 0.01) but not with a significant change in respiratory system compliance (33 [24–47] vs. 35 [25–47] mL/cmH₂O; p = 0.74).

Conclusion

After the LRM, patients with high recruitability presented a significant increase in respiratory system compliance (indicating a gain in ventilated area), while those with low recruitability presented a decrease in pulse pressure suggesting a drop in cardiac output and therefore in intrapulmonary shunt.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-021-03876-z.

Transoesophageal Ultrasound Assessment of Lung Aeration in Patients With Acute Respiratory Distress Syndrome

Introduction: The effect of positive end-expiratory pressure (PEEP) depends closely on the potential for lung recruitment. Bedside assessment of lung recruitability is crucial for personalized lung-protective mechanical ventilation in acute respiratory distress syndrome (ARDS) patients. Methods: We developed a transoesophageal lung ultrasound (TE-LUS) method in which a quantitative (computer-assisted) grayscale determination served as a guide to PEEP-induced lung recruitment. The method is based on the following hypothesis: when the PEEP increases, inflation of the recruited alveoli leads to significant changes in the air/water ratio. Normally ventilated areas are hypoechoic because the ultrasound waves are weakly reflected while poorly aerated areas or non-aerated areas are hyperechoic. We calculated the TE-LUS re-aeration score (RAS) as the ratio of the mean gray scale level at low PEEP to that value at high PEEP for the lower and upper lobes. A RAS > 1 indicated an increase in ventilated area. We used this new method to detect changes in ventilation in patients with a low (<0.5) vs. high (≥0.5) recruitment-to-inflation (R/I) ratio (i.e., the ratio between the recruited lung compliance and the respiratory system compliance at low PEEP). Results: We included 30 patients with moderate-to-severe ARDS. In patients with a high R/I ratio, the TE-LUS RAS was significantly higher in the lower lobes than in the upper lobes (1.20 [1.12-1.63] vs. 1.05 [0.89-1.38]; p = 0.05). Likewise, the TE-LUS RAS in the lower lobes was significantly higher in the high R/I group than in the low R/I group (1.20 [1.12-1.63] vs. 1.07 [1.00-1.20]; p = 0.04). Conclusion: The increase in PEEP induces a substantial gain in the ventilation detected by TE-LUS of poorly or non-aerated lower lobes (dependent lung regions), especially in patients with a high R/I ratio.

POS0469 FALL RISK ASSESSMENT IN RHEUMATOID ARTHRITIS PATIENTS

Background:

Rheumatoid arthritis patients may have an increased risk of falls due to changes caused by the disease such as muscle weakness, joint impairment, reduced mobility and postural instability.

Objectives:

The aim of this study was to analyze the occurrence of falls in RA patients and its risk factors.

Methods:

Between January2020 and July 2020, 51 patients with RA were included in the study. fall history, and the number of falls within the past 12 month were questioned. All participants were assessed with Timed Up and Go Test (TUGT), One-Leg Stand Test (OLST), Walking and Talking Test (WTT), Sternal Push Test (SPT), Tinetti Test (TT), Four Test Balance Scale (FTBS), The Short Falls Efficacy Scale-International (FES-I), Pain Severity and Patient Global Assessment (PGA) by Visual Analog Scale (VAS), disability by the Health Assessment Questionnaire (HAQ), and disease activity by Disease Activity Score in 28 joints (DAS28) were evaluated in for for each patient. The Kolmogorov-Smirnov, Mann-Whitney and chi-square tests were performed with a significance level of P ≤ 0.05.

Results:

22 patients had at least one or more falls. The average age was 54.9±11.5 years with a female predominance (sex ratio = 0.13). Comparing the two groups of patients: those with a history of falls and those without, patients with previous falls were mainly married women (p=0.57), with a low intellectual level (p=0.63). The body mass index in this group was higher (p=0.01) with respectively a higher number of painful and swollen joints (p=0.16, p=0.07); the mean HAQ was higher (p=0.03), and the mean VAS was more important (p=0.05). 12/22 patients had co-morbidities and were poly-medicated.20/22 had joint feet deformities (hallux valgus was the most common deformity). 21/22 were on low dosage corticosteroid therapy. The mean TUGT was 18.5 seconds (>14 seconds). The OLST was less than 5 seconds in 12/22, the sternal push test was positive in 9/22, WTT was positive in 6/22 and the mean tinetti test was 22.4±5.4 suggesting a high risk of falls. The average Short FES-I was 14.6 ±4.4 reflecting a high fear of falls in this group of patients.

Conclusion:

Knowledge about risk factors can help to identify high-risk patients in order to decrease their risk of falling, thus preventing fall-related injuries.

Disclosure of Interests:

None declared

Positive end-expiratory pressure in COVID-19-related ARDS: Do not forget the airway closure

Airway closure is a physiological phenomenon in which the distal airways are obstructed when the airway pressure drops below the airway opening pressure. We assessed this phenomenon in 27 patients with coronavirus disease 2019-related acute respiratory distress syndrome. Twelve (44%) patients had an airway opening pressure above 5 cmH₂O. The median airway opening pressure was 8 cmH₂O (interquartile range, 7–10), with a maximum value of 17 cmH₂O. Three patients had a baseline positive end-expiratory pressure lower than the airway opening pressure.

The PRICES statement: an ESICM expert consensus on methodology for conducting and reporting critical care echocardiography research studies

PURPOSE

Echocardiography is a common tool for cardiac and hemodynamic assessments in critical care research. However, interpretation (and applications) of results and between-study comparisons are often difficult due to the lack of certain important details in the studies. PRICES (Preferred Reporting Items for Critical care Echocardiography Studies) is a project endorsed by the European Society of Intensive Care Medicine and conducted by the Echocardiography Working Group, aiming at producing recommendations for standardized reporting of critical care echocardiography (CCE) research studies.

METHODS

The PRICE panel identified lists of clinical and echocardiographic parameters (the "items") deemed important in four main areas of CCE research: left ventricular systolic and diastolic functions, right ventricular function and fluid management. Each item was graded using a critical index (CI) that combined the relative importance of each item and the fraction of studies that did not report it, also taking experts' opinion into account.

RESULTS

A list of items in each area that deemed essential for the proper interpretation and application of research results is recommended. Additional items which aid interpretation were also proposed.

CONCLUSION

The PRICES recommendations reported in this document, as a checklist, represent an international consensus of experts as to which parameters and information should be included in the design of echocardiography research studies. PRICES recommendations provide guidance to scientists in the field of CCE with the objective of providing a recommended framework for reporting of CCE methodology and results.

Invasive Tracheobronchial Aspergillosis in Critically Ill Patients with Severe Influenza. A Clinical Trial

Rationale: Invasive tracheobronchial aspergillosis (ITBA) is an uncommon but severe clinical form of invasive pulmonary aspergillosis in which the fungal infection is entirely or predominantly confined to the tracheobronchial tree.Objectives: To analyze the diagnostic and prognostic differences between tracheobronchial aspergillosis and pulmonary aspergillosis without tracheobronchial lesions among patients admitted to the ICU with severe influenza.Methods: This retrospective, observational study included critically ill patients with influenza associated with pulmonary aspergillosis from three hospital ICUs between 2010 and 2019. Patient characteristics and clinical and mycologic data at admission and during ICU stay were collected in a database to evaluate variables in the two groups.Measurements and Main Results: Thirty-five patients admitted to the ICU with severe influenza and pulmonary aspergillosis were included. Ten patients were included in the group with ITBA (n = 10 of 35; 28.6%), and 25 patients were included in the group without ITBA. The group with ITBA comprised more patients with active smoking, diabetes mellitus, and higher severity scores (Simplified Acute Physiology Score II). Ninety-day mortality rates in the groups with and without ITBA were 90% and 44%, respectively (P = 0.02). Moreover, significantly higher serum 1,3-β-d-glucan and galactomannan and BAL fluid galactomannan concentrations were observed in the group with ITBA compared with the group without ITBA (P < 0.0001, P = 0.003, and P = 0.008, respectively).Conclusions: ITBA was associated with higher severity scores, mortality, and serum and BAL fluid galactomannan and 1,3-β-d-glucan concentrations than invasive pulmonary aspergillosis without tracheobronchial lesions. ITBA should be systematically researched by bronchoscopic examination in ICU patients with concomitant pulmonary aspergillosis and influenza.Clinical trial registered with www.clinicaltrials.gov (NCT04077697).

Early detection of skin and cardiac amyloid deposits among asymptomatic carriers of hereditary pathogenic transthyretin mutation with normal electroneuromyography

Introduction

During the last decade, disease modifying therapies have been proposed for hereditary amyloidogenic transthyretin (ATTRv) amyloidosis. It is essential to screen for disease onset among asymptomatic mutation carriers in order to trigger effective therapy as early as possible. We describe clinical and paraclinical data from ATTRv asymptomatic carriers, as a baseline assessment to detect disease onset and progression.

Methods

We retrospectively collected data of asymptomatic ATTRv carriers with normal electroneuromyography (ENMG), between March 1st 2015 and January 31st 2019, including: demographics, symptoms, physical exam, ENMG (initial and follow-up obtained in 73 patients, 56.2%), neurovegetative tests, skin biopsy (amyloid deposition, denervation), and cardiac evaluation (multimodal imaging, cardiac denervation and arrhythmias).

Results

We included 130 patients, aged 43.6 years (± 13.5), selected in family of a proband with an age of onset of 52.7 years (±15.7), 40.8% male, carrying 20 different variants of the TTR gene, including 63.8% Val30Met. Amyloid deposits on skin biopsy and/or cardiac fixation on bone scintigraphy, characteristic of amyloid infiltration, were found in 22/130 patients (16%). Skin biopsy was positive in 11 patients, and cardiac fixation on bone scintigraphy was positive in 15 patients. Amyloid infiltration was statistically associated with age (p=0.024), age difference from index case (p&lt;0.001), electrophysiological carpal tunnel syndrome (p=0.022), interventricular septum thickness &gt;12 mm (p&lt;0.001), contrast enhancement in cardiac MRI (p=0.002), cardiac denervation using MIBG scintigraphy C/M ratio &lt;1.85 (p=0.044). Multivariate analysis showed that age difference with index case and interventricular septum thickness were predictors for amyloid infiltration (OR=1.11, IC [1,04–1,19] and OR=1,76, IC [1,19–2,60]). Subgroup analysis showed electroneuromyography alteration during follow up in 11 patients (delay 26.9 months, range 10–49) with statistic association with amyloid deposits (55.6 versus 7.1% when ENMG was unchanged, p&lt;0.001) and interventricular septum thickness (p&lt;0.010).

Conclusion

Clinical and paraclinical assessment of asymptomatic carriers of ATTRv mutations shows that skin or cardiac amyloid infiltration may precede ENMG abnormalities in 16% of patients. This may trigger specific therapies in borderline cases. Age close to age of onset among index case and septum interventricular thickness appear as risk factors for developing electroneuromyogram alteration.

Funding Acknowledgement

Type of funding source: None

Expert consensus-based clinical practice guidelines management of intravascular catheters in the intensive care unit

The French Society of Intensive Care Medicine (SRLF), jointly with the French-Speaking Group of Paediatric Emergency Rooms and Intensive Care Units (GFRUP) and the French-Speaking Association of Paediatric Surgical Intensivists (ADARPEF), worked out guidelines for the management of central venous catheters (CVC), arterial catheters and dialysis catheters in intensive care unit. For adult patients: Using GRADE methodology, 36 recommendations for an improved catheter management were produced by the 22 experts. Recommendations regarding catheter-related infections’ prevention included the preferential use of subclavian central vein (GRADE 1), a one-step skin disinfection(GRADE 1) using 2% chlorhexidine (CHG)-alcohol (GRADE 1), and the implementation of a quality of care improvement program. Antiseptic- or antibiotic-impregnated CVC should likely not be used (GRADE 2, for children and adults). Catheter dressings should likely not be changed before the 7th day, except when the dressing gets detached, soiled or impregnated with blood (GRADE 2− adults). CHG dressings should likely be used (GRADE 2+). For adults and children, ultrasound guidance should be used to reduce mechanical complications in case of internal jugular access (GRADE 1), subclavian access (Grade 2) and femoral venous, arterial radial and femoral access (Expert opinion). For children, an ultrasound-guided supraclavicular approach of the brachiocephalic vein was recommended to reduce the number of attempts for cannulation and mechanical complications. Based on scarce publications on diagnostic and therapeutic strategies and on their experience (expert opinion), the panel proposed definitions, and therapeutic strategies.

COVID-19 : profil patient prédisposant à une admission précoce en service de Réanimation

Introduction

Même si la majorité des patients atteints n’ont que des symptômes bénins, certains, plus graves, nécessitent une hospitalisation en service de soins voire une admission en réanimation. En raison du risque de létalité élevé, ces patients doivent être étroitement surveillés.

L’objectif de notre étude est de définir des profils patients qui pourraient favoriser une admission précoce en service de réanimation et de définir des marqueurs pouvant appuyer cette admission.

Matériels et méthodes

Étude rétrospective monocentrique du profil des patients admis en réanimation entre le 1^er mars et le 26 avril 2020. Les données démographiques des patients (âge, sexe, poids, indice de masse corporelle, statut tabagique), les données biologiques à l’admission en réanimation, les antécédents cliniques ainsi que les traitements médicamenteux ont été recueillis.

Deux groupes ont été constitués en fonction du délai entre la date de début des symptômes et la date d’entrée en réanimation : strictement inférieur à 7 jours (G1, admission précoce) et supérieur ou égal à 7 jours (G2, admission tardive). Une analyse statistique comparative par un test de Student pour les variables continues et du Chi² pour les variables catégorielle a été effectuée.

Résultats

Au total, la cohorte comprend 127 patients dont 62 dans le G1 et 65 dans le G2. L’analyse des données démographiques montre un IMC (31,5 dans le G1 vs 29,2 dans le G2 ; p = 0,04) et un âge (66,5 vs 60,6 ; p ≤ 0,01) supérieur dans le G1.

Le taux d’hypokaliémie (0,27 vs 0,09 ; p ≤ 0,01), d’hypocalcémie (0,56 vs 0,32 ; p ≤ 0,01), d’hypercréatininémie (0,42 vs 0,17 ; p ≤ 0,01) et d’hyperferritinémie (0,96 vs 0,63 ; p ≤ 0,01) semble être significativement plus élevée dans le G1.

De plus, la proportion de patients avec des antécédents cardiovasculaires (0,57 vs 0,34 ; p ≤ 0,01) et/ou diabétiques (0,25 vs 0,10 ; p = 0,02) sont plus élevés dans le G1. Le nombre de traitement moyen (4,5 vs 3,0 ; p = 0,04) et en particulier de médicaments à visée cardiovasculaire (0,60 vs 0,39 ; p = 0,02) est aussi plus fréquent dans le G1. Enfin, le taux de mortalité (0,31 vs 0,12 ; p = 0,01) est plus élevé dans le G1 que dans le G2.

Conclusion

Des profils patients se dessinent selon les données objectivées par cette étude. Les patients obèses, et en particulier en obésité morbide (avec un IMC > 35 kg/m²), ainsi que les patients âgés sont à risque d’être admis précocement en réanimation. Il en est de même pour les patients avec de nombreux antécédents cardiovasculaires et/ou diabétiques, les patients polymédiqués et notamment ceux traités par des médicaments à visée cardiovasculaire.

Parmi les éléments biologiques relevés, l’hypokaliémie, l’hyperferritinémie (avec des valeurs moyennes très hautes dans le G1), l’insuffisance rénale et l’hypocalcémie semblent favoriser une admission précoce en réanimation.

Les taux de mortalité en réanimation étant élevés (20 % à plus de 60 % selon le profil du patient), il est important de repérer les marqueurs et les facteurs prédisposant à une admission en réanimation. La priorisation de la prise en charge de ces patients permettrait d’éviter leur passage en soins intensifs et pourrait avoir un impact sur la mortalité.

Association between renin-angiotensin system inhibitors and COVID-19 complications

Aims

To describe the characteristics of patients hospitalized with COVID-19 (including their long-term at-home medication use), and compare them with regard to the course of the disease. To assess the association between renin–angiotensin system inhibitors (RASIs) and disease progression and critical outcomes.

Methods and results

All consecutive hospitalized patients with laboratory-confirmed COVID-19 in a university hospital in Amiens (France) were included in this study. The primary composite endpoint was admission to an intensive care unit (ICU) or death before ICU admission. Univariable and multivariable logistic regression models were used to identify factors associated with the composite endpoint. Between 28 February 2020 and 30 March 2020, a total of 499 local patients tested positive for SARS-CoV-2. Of these, 231 were not hospitalized {males 33%; median [interquartile range (IQR)] age: 44 (32–54)}, and 268 were hospitalized [males 58%; median (IQR) age: 73 (61–84)]. A total of 116 patients met the primary endpoint: 47 died before ICU admission, and 69 were admitted to the ICU. Patients meeting the primary endpoint were more likely than patients not meeting the primary endpoint to have coronary heart disease and to have been taking RASIs; however, the two subsets of patients did not differ with regard to median age. After adjustment for other associated variables, the risk of meeting the composite endpoint was 1.73 times higher (odds ratio 1.73, 95% confidence interval 1.02–2.93) in patients treated at baseline with a RASI than in patients not treated with this drug class. This association was confirmed when the analysis was restricted to patients treated with antihypertensive agents.

Conclusions

We highlighted a potential safety signal for RASIs, the long-term use of which was independently associated with a higher risk of severe COVID-19 and a poor outcome. Due to the widespread use of this important drug class, formal proof based on clinical trials is needed to better understand the association between RASIs and complications of COVID-19.

Systematic review and literature appraisal on methodology of conducting and reporting critical-care echocardiography studies: a report from the European Society of Intensive Care Medicine PRICES expert panel

Background

The echocardiography working group of the European Society of Intensive Care Medicine recognized the need to provide structured guidance for future CCE research methodology and reporting based on a systematic appraisal of the current literature. Here is reported this systematic appraisal.

Methods

We conducted a systematic review, registered on the Prospero database. A total of 43 items of common interest to all echocardiography studies were initially listed by the experts, and other “topic-specific” items were separated into five main categories of interest (left ventricular systolic function, LVSF n = 15, right ventricular function, RVF n = 18, left ventricular diastolic function, LVDF n = 15, fluid management, FM n = 7, and advanced echocardiography techniques, AET n = 17). We evaluated the percentage of items reported per study and the fraction of studies reporting a single item.

Results

From January 2000 till December 2017 a total of 209 articles were included after systematic search and screening, 97 for LVSF, 48 for RVF, 51 for LVDF, 36 for FM and 24 for AET. Shock and ARDS were relatively common among LVSF articles (both around 15%) while ARDS comprised 25% of RVF articles. Transthoracic echocardiography was the main echocardiography mode, in 87% of the articles for AET topic, followed by 81% for FM, 78% for LVDF, 70% for LVSF and 63% for RVF. The percentage of items per study as well as the fraction of study reporting an item was low or very low, except for FM. As an illustration, the left ventricular size was only reported by 56% of studies in the LVSF topic, and half studies assessing RVF reported data on pulmonary artery systolic pressure.

Conclusion

This analysis confirmed sub-optimal reporting of several items listed by an expert panel. The analysis will help the experts in the development of guidelines for CCE study design and reporting.

Conjunctival lymphangiectasia as a biomarker of severe systemic disease in Ser77Tyr hereditary transthyretin amyloidosis

AIMS

To investigate the relationship between the ophthalmic and systemic phenotypes in patients with hereditary transthyretin amyloidosis with the S77Y mutation (ATTRS77Y).

METHODS

In this cross-sectional study, patients with genetically confirmed ATTRS77Y amyloidosis were enrolled. All patients underwent complete neurological examination, including staging with the Neuropathy Impairment Score (NIS), Polyneuropathy Disability (PND) score; complete cardiological evaluation, including echocardiography, cardiac MRI and/or cardiac scintigraphy and complete ophthalmic evaluation, including slit lamp examination and fundus examination. Ocular ancillary tests (fluorescein and indocyanine green angiography, and anterior segment optical coherence tomography) were performed in cases with abnormal findings. The Kruskal-Wallis test was used for quantitative outcomes and Fisher's exact test for qualitative outcomes. Statistical significance was indicated by p<0.05 (two tailed).

RESULTS

The study sample was composed of 24 ATTRS77Y patients. The mean patient age was 58.4±12.4 years. None of the patients presented with amyloid deposits in the anterior chamber, secondary glaucoma or vitreous amyloidosis. Retinal angiopathy was observed in four patients, complicated with retinal ischaemia in one patient. Conjunctival lymphangiectasia (CL) was detected in 13 patients (54%), associated with perilymphatic amyloid deposits. The presence of CL was statistically associated with more severe neurological disease (NIS=43.3±31.9 vs 18.9±20.4; PND=2.6±1.0 vs 1.4±0.7 in patients with and without CL, respectively; both p<0.05) and amyloid cardiomyopathy (p=0.002).

CONCLUSION

In ATTRS77Y patients, CL is common and could serve as a potential biomarker for severe systemic disease. There were neither anterior chamber deposits, secondary glaucoma nor vitreous deposits in ATTRS77Y patients.

Feasibility of myocardial perfusion assessment with contrast echocardiography: can it improve recognition of significant coronary artery disease in the ICU?

BACKGROUND

Diagnosis of significant coronary artery disease (CAD) and acute coronary artery occlusion in ICU can be difficult, and an inappropriate intervention is potentially harmful. Myocardial contrast perfusion echo (MCPE) examines ultrasound contrast intensity replenishment curves in individual myocardial segments measuring peak contrast intensity and slope of return as an index of myocardial blood flow (units = intensity of ultrasound per second [dB/s]). MCPE could possibly serve as a triage tool to invasive angiography by estimating blood flow in the myocardium. We sought to assess feasibility in the critically ill and if MCPE could add incremental value to the clinical acumen in predicting significant CAD.

METHODS

This is a single-centre, prospective, observational study. Inclusion criteria were as follows: adult ICU patients with troponin I > 50 ng/L and cardiology referral being made for consideration of inpatient angiography. Exclusion criteria were as follows: poor echo windows (2 patients), known ischaemic heart disease, and contrast contraindications. Seven cardiologists and 6 intensivists blinded to outcome assessed medical history, ECG, troponin, and 2D echo images to estimate likelihood of significant CAD needing intervention (clinical acumen). Clinical acumen, quantitative MCPE, and subjective (visual) MCPE were assessed to predict significant CAD.

RESULTS

Forty patients underwent MCPE analysis, 6 (15%) had significant CAD, and median 11 of 16 segments (IQR 8-13) could be imaged (68.8% [IQR 50-81]). No adverse events occurred. A significant difference was found in overall MCPE blood flow estimation between those diagnosed with significant CAD and those without (3.3 vs 2.4 dB/s, p = 0.050). A MCPE value of 2.8 dB/s had 67% sensitivity and 88% specificity in detecting significant CAD. Clinical acumen showed no association in prediction of CAD (OR 0.6, p = 0.09); however, if quantitative or visual MCPE analysis was included, a significant association occurred (OR 17.1, p = 0.01; OR 23.0, p = 0.01 respectively).

CONCLUSIONS

MCPE is feasible in the critically ill and shows better association with predicting significant CAD vs clinical acumen alone. MCPE adds incremental value to initial assessment of the presence of significant CAD which may help guide those who require urgent angiography.

The stop-flow arm equilibrium pressure in preoperative patients: Stressed volume and correlations with echocardiography

BACKGROUND

The distending intravascular pressure at no flow conditions reflects the stressed volume. While this haemodynamic variable is recognised as clinically important, there is a paucity of reports of its range and responsiveness to volume expansion in patients without cardiovascular disease and no reports of correlations to echocardiographic assessments of left ventricular filling.

METHODS

Twenty-seven awake (13 male), spontaneously breathing patients without any history of cardiopulmonary, vascular or renal disease were studied prior to induction of anaesthesia. The no-flow equilibrium pressure in the arm following rapid circulatory occlusion (P_arm ) was measured via a radial arterial catheter. Transthoracic echocardiography was used to measure left ventricular end diastolic area and volume as well as the diameter of the inferior vena cava. The P_arm and echocardiographic variables were measured before and after administration of 500 mL 0.9% NaCl over 10 minutes. Changes were analysed by paired t test, Pearson's correlation and multiple linear regression.

RESULTS

P_arm increased overall from 22 ± 5 mm Hg to 25 ± 6 mm Hg (mean difference 3.0 ± 4.5 mm Hg, P = 0.002) following the fluid bolus with corresponding increases in arterial pressure and echocardiographic variables. Variability in the direction of the P_arm response reflected concomitant changes in vascular compliance. Only weak correlations were observed between changes in P_arm and inferior vena cava diameter indexed to body surface area (R²  = 0.29, P = 0.01).

CONCLUSION

Preoperative measurements of P_arm increased following acute expansion of the intravascular volume. Echocardiography demonstrated poor correlation with P_arm .

Subjective right ventricle assessment by echo qualified intensive care specialists: assessing agreement with objective measures

BACKGROUND

Right ventricle (RV) size and function assessment by echocardiography (echo) is a standard tool in the ICU. Frequently subjective assessment is performed, and guidelines suggest its utility in adequately trained clinicians. We aimed to compare subjective (visual) assessment of RV size and function by ICU physicians, with advanced qualifications in echocardiography, vs objective measurements.

METHODS

ICU specialists with a qualification in advanced echocardiography reviewed 2D echo clips from critically ill patients on mechanical ventilation with PaO2:FiO2 < 300. Subjective assessments of RV size and function were made independently using a three-class categorical scale. Agreement (B-score) and bias (p value) were analysed using objective echo measurements. RV size assessment included RV end-diastolic area (EDA) and diameters. RV function assessment included fractional area change, S', TAPSE and RV free wall strain. Binary and ordinal analysis was performed.

RESULTS

Fifty-two clinicians reviewed 2D images from 80 patients. Fair agreement was seen with objective measures vs binary assessment of RV size (RV EDA 0.26 [p < 0.001], RV dimensions 0.29 [p = 0.06]) and function (RV free wall strain 0.27 [p < 0.001], TAPSE 0.27 [p < 0.001], S' 0.29 [p < 0.001], FAC 0.31 [p = 0.16]). However, ordinal data analysis showed poor agreement with RV dimensions (0.11 [p = 0.06]) and RV free wall strain (0.14 [p = 0.16]). If one-step disagreement was allowed, agreement was good (RV dimensions 0.6 [p = 0.06], RV free wall strain 0.6 [p = 0.16]). Significant overestimation of severity of abnormalities was seen with subjective assessment vs RV EDA, TAPSE, S' and fractional area change.

CONCLUSION

Subjective (visual) assessment of RV size and function, by ICU specialists trained in advanced echo, can be fairly reliable for the initial exclusion of significant RV pathology. It seems prudent to avoid subjective RV assessment in isolation.

[ST-elevation myocardial infarction (STEMI) in the elderly]

Admission in cardiology departments of patients over 80 years old, even nonagenarians, for ST-segment elevation myocardial infarction (STEMI) is not uncommon in 2018. The management of these high risk and polypathological patients, with atypical clinical presentation, is not based on international guidelines or randomized studies, but rather on retrospective studies, expert consensus, and common sense. Each decision has to be individualized to the patient's situation. This review, after a clinical case, aims to guide the clinician in the specific management of these patients, from the symptoms, to reperfusion strategy, and, as fast as possible, hospital discharge.

Feasibility of biventricular 3D transthoracic echocardiography in the critically ill and comparison with conventional parameters

Background

Transthoracic 3D cardiac analysis is enticing in its potential simplicity and wealth of data available. It has been suggested to be accurate vs magnetic resonance imaging in relatively stable patients, but feasibility and agreement with conventional echocardiographic assessment of stroke volume (SV) have not been thoroughly assessed in critically ill patients, who are traditionally harder to image. The objectives of this study were to compare 3D transthoracic volumetric analysis vs Doppler assessment of SV (which is suggested to be accurate in the critically ill) and Simpson’s biplane assessment in a cohort typical of the intensive care unit (ICU), where accurate assessment is important: mechanically ventilated patients with a significant ventilation/perfusion (V/Q) mismatch. We hypothesised that it would be feasible but might lack agreement.

Methods

Patients were imaged within 24 hours of admission. Inclusion criteria were adult patients, V/Q mismatch present (defined as a ratio of arterial oxygen partial pressure to fractional inspired oxygen < 300), and mechanically ventilated with Doppler SV assessment possible. Biventricular echocardiographic volumetric analysis was performed using Siemens SC2000 along with standard Simpson’s biplane and Doppler SV assessment. 3D images were unacceptable if two segments or more were unable to be seen in two volumetric planes. 3D left ventricular (3DLV) and 3D right ventricular (3DRV) analyses were performed with the Tomtec Imaging and Siemens Acuson platforms, respectively.

Results

Ninety-two patients were included (83 in sinus, 9 in atrial fibrillation). 3DLV and 3DRV analyses were feasible in 72% and 55% of patients, respectively; however, they underestimated SV compared with Doppler by 2.6 ml (± 10.4) and 4.1 ml (± 15.4), respectively. Limits of agreement for 2D, 3DLV and 3DRV volumetric analysis techniques were large.

Conclusions

3DLV and 3DRV volumetric analyses appear feasible (obtainable) in the majority of mechanically ventilated ICU patients. Compared with the Doppler method, 3DLV and 3DRV volumetric analyses underestimate SV. The large limits of agreement between the methods also cast doubt on their comparability. Given the scenarios in which SV analysis is required (e.g., assessment of cardiac performance), our study cautions against the use of 3D SV clinically.

The comparative effects of 3% saline and 0.5M sodium lactate on cardiac function:a randomised, crossover study in volunteers

OBJECTIVE

To investigate the metabolic and cardiac effects of intravenous administration of two hypertonic solutions - 3% saline (SAL) and 0.5M sodium lactate (LAC).

DESIGN, SETTING AND PARTICIPANTS

A randomised, doubleblind, crossover study in ten human volunteers. Intravenous bolus of either SAL or LAC at 3 mL/kg over 20 min followed by a 2 mL/kg infusion over 60 min.

MAIN OUTCOME MEASURES

Acid base parameters and echocardiographic indices of cardiac function, cardiac output (CO), left ventricular ejection fraction (LVEF) and mitral annular peak systolic velocity (Sm) before and after infusion of SAL or LAC.

RESULTS

Despite haemodilution, we observed an increase in sodium (139 ± 2 mmol/L to 142 ± 2 mmol/L in both groups) and respective anions, chloride (106 ± 2 mmol/L to 112 ± 3 mmol/L) and lactate (1.01 ± 0.28 mmol/L to 2.38 ± 0.38 mmol/L) with SAL and LAC, respectively. The pH (7.37 ± 0.03 to 7.45 ± 0.03; P < 0.01) and simplified strong ion difference (SID) (36.3 ± 4.6 mmol/L to 39.2 ± 3.6 mmol/L; P < 0.01) increased during the LAC infusion. The pH was unchanged, but SID decreased during SAL infusion (36.3 ± 2.5 mmol/L to 33.9 ± 3.1 mmol/L; P = 0.01). Both solutions led to an increase in preload and cardiac function, CO (4.36 ± 0.79 L/min to 4.98 ± 1.37 L/ min v 4.62 ± 1.30 L/min to 5.13 ± 1.44 L/min), LVEF (61 ± 6% to 63 ± 8% v 64 ± 6% to 68 ± 7%). The averaged Sm improved in the LAC group as compared with the SAL group (0.088 ± 0.008 to 0.096 ± 0.016 v 0.086 ± 0.012 to 0.082 ± 0.012; P = 0.032).

CONCLUSIONS

The administration of SAL or LAC has opposing effects on acid base variables such as SID. Hypertonic fluid infusion lead to increased cardiac preload and performance with Sm, suggesting better left ventricular systolic function during LAC as compared with SAL. Lactated hypertonic solutions should be evaluated as resuscitation fluids.

The presence of elastic compression stockings reduces the fluid responsiveness of patients in the operating room

BACKGROUND

The aim of this study was to investigate whether elastic compression stockings (ECS) can affect fluid responsiveness parameters before and during passive leg raising (PLR) maneuvers.

METHODS

In the operating room (OR), we performed a prospective study including patients referred for cardiac surgery. Blood pressure (BP), ΔPP, heart rate (HR), central venous pressure (CVP), stroke volume (SV) and aortic blood flow (ABF) (by esophageal doppler) were measured according to four conditions: supine position without ECS (baseline 1), lower limbs raised to an angle of 45° (PLR 1), returned to the supine position with ECS (baseline 2), then a second PLR maneuver with ECS was performed (PLR 2).

RESULTS

Twenty patients were included. BP, SV, ABF and CVP increased significantly. ΔPP and HR decreased during PLR 1. At baseline 2, HR and ΔPP decreased significantly compared to baseline 1. During PLR 2, increase of SV (4% [9]) and ABF (4% [9]), and the decrease of ΔPP (-19% [104]) were significantly lower than those observed at PLR 1 (7% [21] P=0.05; 9% [8] P=0.02 and -66% [40] P=0.02, respectively). Eleven patients presented a ΔPP≥13% at baseline 1. Only 1 patient still presented a ΔPP≥13% with ECS at baseline 2. Only 3/9 patients with an increase of ABF ≥10% and 2/11 patients with an increase of PP ≥12% during the PLR 1 presented similar results during PLR 2.

CONCLUSIONS

In the OR, ECS provoke a self-fluid loading increasing ABF, decreasing ΔPP and PLR response. The presence of ECS should be considered when managing hemodynamic parameters of patients.

Hydrocortisone plus Fludrocortisone for Adults with Septic Shock

BACKGROUND

Septic shock is characterized by dysregulation of the host response to infection, with circulatory, cellular, and metabolic abnormalities. We hypothesized that therapy with hydrocortisone plus fludrocortisone or with drotrecogin alfa (activated), which can modulate the host response, would improve the clinical outcomes of patients with septic shock.

METHODS

In this multicenter, double-blind, randomized trial with a 2-by-2 factorial design, we evaluated the effect of hydrocortisone-plus-fludrocortisone therapy, drotrecogin alfa (activated), the combination of the three drugs, or their respective placebos. The primary outcome was 90-day all-cause mortality. Secondary outcomes included mortality at intensive care unit (ICU) discharge and hospital discharge and at day 28 and day 180 and the number of days alive and free of vasopressors, mechanical ventilation, or organ failure. After drotrecogin alfa (activated) was withdrawn from the market, the trial continued with a two-group parallel design. The analysis compared patients who received hydrocortisone plus fludrocortisone with those who did not (placebo group).

RESULTS

Among the 1241 patients included in the trial, the 90-day mortality was 43.0% (264 of 614 patients) in the hydrocortisone-plus-fludrocortisone group and 49.1% (308 of 627 patients) in the placebo group (P=0.03). The relative risk of death in the hydrocortisone-plus-fludrocortisone group was 0.88 (95% confidence interval, 0.78 to 0.99). Mortality was significantly lower in the hydrocortisone-plus-fludrocortisone group than in the placebo group at ICU discharge (35.4% vs. 41.0%, P=0.04), hospital discharge (39.0% vs. 45.3%, P=0.02), and day 180 (46.6% vs. 52.5%, P=0.04) but not at day 28 (33.7% and 38.9%, respectively; P=0.06). The number of vasopressor-free days to day 28 was significantly higher in the hydrocortisone-plus-fludrocortisone group than in the placebo group (17 vs. 15 days, P<0.001), as was the number of organ-failure-free days (14 vs. 12 days, P=0.003). The number of ventilator-free days was similar in the two groups (11 days in the hydrocortisone-plus-fludrocortisone group and 10 in the placebo group, P=0.07). The rate of serious adverse events did not differ significantly between the two groups, but hyperglycemia was more common in hydrocortisone-plus-fludrocortisone group.

CONCLUSIONS

In this trial involving patients with septic shock, 90-day all-cause mortality was lower among those who received hydrocortisone plus fludrocortisone than among those who received placebo. (Funded by Programme Hospitalier de Recherche Clinique 2007 of the French Ministry of Social Affairs and Health; APROCCHSS ClinicalTrials.gov number, NCT00625209 .).

Paradoxical septal motion: A diagnostic approach and clinical relevance

Abnormal septal motion (commonly referred to as septal bounce) is a common echocardiographic finding that occurs with several conditions, including the following: mitral stenosis, left bundle branch block, pericardial syndromes and severe pulmonary hypertension. We explore the subtle changes that occur on M-mode imaging of the septum, other associated echocardiographic features, the impact of inspiratory effort on septal motion and relevant clinical findings. Finally, we discuss the impact of abnormal septal motion on cardiac form and function, proposing there is a clinically significant impact on biventricular filling and ejection.

Application of updated guidelines on diastolic dysfunction in patients with severe sepsis and septic shock

Background

Left ventricular diastolic dysfunction is suggested to be associated with higher mortality in severe sepsis and septic shock, yet the methods of diagnosis described in the literature are often inconsistent. The recently published 2016 American Society of Echocardiography and European Association of Cardiovascular Imaging (ASE/EACVI) guidelines offer the opportunity to apply a simple pragmatic diagnostic algorithm for the detection of diastolic dysfunction; however, it has not been tested in this cohort.

Aims

We sought to assess the applicability in septic patients of recently published 2016 ASE/EACVI guidelines on diastolic dysfunction compared with the 2009 ASE guidelines. Our hypothesis was that there would be poor agreement in classifying patients.

Methods

Prospective observational study includes patients identified as having severe sepsis and septic shock. Patients underwent transthoracic echocardiography on day 1 and day 3 of their ICU admission. Patients with normal and abnormal (ejection fraction < 52%) systolic function had their diastolic function stratified according to both the 2009 ASE and 2016 ASE/EACVI guidelines.

Results

On day 1 echocardiography, of the 62 patients analysed, 37 (60%) had diastolic dysfunction according to the 2016 ASE/EACVI guideline with a further 23% having indeterminate diastolic function, compared to the 2009 ASE guidelines where only 13 (21%) had confirmed diastolic dysfunction with 46 (74%) having indeterminate diastolic dysfunction. On day 3, of the 55 patients studied, 22 patients (40%) were defined as having diastolic dysfunction, with 6 (11%) having indeterminate diastolic dysfunction according to the 2016 ASE/EACVI guidelines, compared to the 2009 guidelines where 11 (20%) were confirmed to have diastolic dysfunction and 41 (75%) had indeterminate diastolic function. Systolic dysfunction was identified in 18 of 62 patients (29%) on day 1 and 18 of 55 (33%) on day 3. These patients were classified as having abnormal diastolic function in 94 and 89% with the 2016 guidelines on day 1 and day 3, respectively, compared with 50 and 28% using the 2009 guidelines. The 2016 guidelines had less patients with indeterminate diastolic function on days 1 and 3 (11 and 6%) compared to the 2009 guidelines (50 and 72%). Normal systolic function was identified in 44 patients on day 1 and 37 on day 3. In this group, abnormal diastolic function was present in 45 and 54% on days 1 and 3 according to the 2016 ASE/EACVI guidelines, compared with 9 and 16% using the 2009 guidelines, respectively. In those with normal systolic function, the 2016 guidelines had less indeterminate patients with 30 and 16% on days 1 and 3, respectively, compared to 84 and 76% in the 2009 guidelines.

Conclusion

The 2016 ASE/EACVI diastolic function guidelines identify a significantly higher incidence of dysfunction in patients with severe sepsis and septic shock compared to the previous 2009 guidelines. Although the new guidelines seem to be an improvement, issues remain with the application of guidelines using traditional measures of diastolic dysfunction in this cohort.

Electronic supplementary material

The online version of this article (10.1186/s13613-017-0342-x) contains supplementary material, which is available to authorized users.

Executive summary on the use of ultrasound in the critically ill: consensus report from the 3rd Course on Acute Care Ultrasound (CACU)

Over the past decades, ultrasound (US) has gained its place in the armamentarium of monitoring tools in the intensive care unit (ICU). Critical care ultrasonography (CCUS) is the combination of general CCUS (lung and pleural, abdominal, vascular) and CC echocardiography, allowing prompt assessment and diagnosis in combination with vascular access and therapeutic intervention. This review summarises the findings, challenges lessons from the 3rd Course on Acute Care Ultrasound (CACU) held in November 2015, Antwerp, Belgium. It covers the different modalities of CCUS; touching on the various aspects of training, clinical benefits and potential benefits. Despite the benefits of CCUS, numerous challenges remain, including the delivery of CCUS training to future intensivists. Some of these are discussed along with potential solutions from a number of national European professional societies. There is a need for an international agreed consensus on what modalities are necessary and how best to deliver training in CCUS.

Longitudinal wall fractional shortening: an M-mode index based on mitral annular plane systolic excursion (MAPSE) that correlates and predicts left ventricular longitudinal strain (LVLS) in intensive care patients

Background

Left ventricular longitudinal strain (LVLS) is a modern measurement for LV function. However, strain measurement is often difficult in critically ill patients. We sought to show LVLS can be estimated using M-mode-derived longitudinal wall fractional shortening (LWFS), which is less dependent on image quality and is easier to perform in critically ill patients.

Methods

Transthoracic echocardiographic records were retrospectively screened and 80 studies suitable for strain and M-mode measurements in the apical 4-chamber view were selected. Longitudinal wall fractional shortening was derived from conventional M-mode (LWFS) and curved anatomical M-mode (CAMMFS). The relationships between LVLS and mitral annular plane systolic excusion (MAPSE) and M-mode-derived fractional shortening were examined using univariate generalized linear model in a training set (n = 50) and was validated in a separate validation set (n = 30).

Results

MAPSE, CAMMFS, and LWFS demonstrated very good correlations with LVLS (r = 0.852, 0.875 and 0.909, respectively). LWFS was the best unbiased predictor for LVLS (LVLS = 1.180 x LWFS - 0.737, P < 0.001). Intra- and inter-rater agreement and reliability for LWFS measurement were good.

Conclusions

LVLS can be estimated by LWFS in the critically ill patients. It provides a fast and accurate prediction of LVLS. LWFS is a reproducible and reliable measurement which can be used as a potential index in place of LVLS in the critically ill population.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-017-1876-x) contains supplementary material, which is available to authorized users.

Pearls and pitfalls in comprehensive critical care echocardiography

Critical care echocardiography is developing rapidly with an increasing number of specialists now performing comprehensive studies using Doppler and other advanced techniques. However, this imaging can be challenging, interpretation is far from simple in the complex critically ill patient and mistakes can be easy to make. We aim to address clinically relevant areas where potential errors may occur and suggest methods to hopefully improve accuracy of imaging and interpretation.

Hemodynamic Assessment of Patients With Septic Shock Using Transpulmonary Thermodilution and Critical Care Echocardiography: A Comparative Study

BACKGROUND

To assess the agreement between transpulmonary thermodilution (TPT) and critical care echocardiography (CCE) in ventilated patients with septic shock.

METHODS

Ventilated patients in sinus rhythm requiring advanced hemodynamic assessment for septic shock were included in this prospective multicenter descriptive study. Patients were assessed successively using TPT and CCE in random order. Data were interpreted independently at bedside by two investigators who proposed therapeutic changes on the basis of predefined algorithms. TPT and CCE hemodynamic assessments were reviewed offline by two independent experts who identified potential sources of discrepant results by consensus. Lactate clearance and outcome were studied.

RESULTS

A total of 137 patients were studied (71 men; age, 61 ± 15 years; Simplified Acute Physiologic Score, 58 ± 18; Sequential Organ Failure Assessment, 10 ± 3). TPT and CCE interpretations at bedside were concordant in 87/132 patients (66%) without acute cor pulmonale (ACP), resulting in a moderate agreement (kappa, 0.48; 95% CI, 0.37-0.60). Experts' adjudications were concordant in 100/129 patients without ACP (77.5%), resulting in a good intertechnique agreement (kappa, 0.66; 95% CI, 0.55-0.77). In addition to ACP (n = 8), CCE depicted a potential source of TPT inaccuracy in 8/29 patients (28%). Lactate clearance at H6 was similar irrespective of the concordance of online interpretations of TPT and CCE (55/84 [65%] vs 32/45 [71%], P = .55). ICU and day 28 mortality rates were similar between patients with concordant and discordant interpretations (29/87 [36%] vs 13/45 [29%], P = .60; and 31/87 [36%] vs 16/45 [36%], P = .99, respectively).

CONCLUSIONS

Agreement between TPT and CCE was moderate when interpreted at bedside and good when adjudicated offline by experts, but without impact on lactate clearance and mortality.

Transthoracic echocardiography: an accurate and precise method for estimating cardiac output in the critically ill patient

Background

Cardiac output (CO) monitoring is a valuable tool for the diagnosis and management of critically ill patients. In the critical care setting, few studies have evaluated the level of agreement between CO estimated by transthoracic echocardiography (CO-TTE) and that measured by the reference method, pulmonary artery catheter (CO-PAC). The objective of the present study was to evaluate the precision and accuracy of CO-TTE relative to CO-PAC and the ability of transthoracic echocardiography to track variations in CO, in critically ill mechanically ventilated patients.

Methods

Thirty-eight mechanically ventilated patients fitted with a PAC were included in a prospective observational study performed in a 16-bed university hospital ICU. CO-PAC was measured via intermittent thermodilution. Simultaneously, a second investigator used standard-view TTE to estimate CO-TTE as the product of stroke volume and the heart rate obtained during the measurement of the subaortic velocity time integral.

Results

Sixty-four pairs of CO-PAC and CO-TTE measurements were compared. The two measurements were significantly correlated (r = 0.95; p < 0.0001). The median bias was 0.2 L/min, the limits of agreement (LOAs) were –1.3 and 1.8 L/min, and the percentage error was 25%. The precision was 8% for CO-PAC and 9% for CO-TTE. Twenty-six pairs of ΔCO measurements were compared. There was a significant correlation between ΔCO-PAC and ΔCO-TTE (r = 0.92; p < 0.0001). The median bias was –0.1 L/min and the LOAs were –1.3 and +1.2 L/min. With a 15% exclusion zone, the four-quadrant plot had a concordance rate of 94%. With a 0.5 L/min exclusion zone, the polar plot had a mean polar angle of 1.0° and a percentage error LOAs of –26.8 to 28.8°. The concordance rate was 100% between 30 and –30°. When using CO-TTE to detect an increase in ΔCO-PAC of more than 10%, the area under the receiving operating characteristic curve (95% CI) was 0.82 (0.62–0.94) (p < 0.001). A ΔCO-TTE of more than 8% yielded a sensitivity of 88% and specificity of 66% for detecting a ΔCO-PAC of more than 10%.

Conclusion

In critically ill mechanically ventilated patients, CO-TTE is an accurate and precise method for estimating CO. Furthermore, CO-TTE can accurately track variations in CO.