Respiratory Monitoring During Mechanical Ventilation: The Present and the Future.

The increased application of mechanical ventilation, the recognition of its harms and the interest in individualization raised the need for an effective monitoring. An increasing number of monitoring tools and modalities were introduced over the past 2 decades with growing insight into asynchrony, lung and chest wall mechanics, respiratory effort and drive. They should be used in a complementary rather than a standalone way. A sound strategy can guide a reduction in adverse effects like ventilator-induced lung injury, ventilator-induced diaphragm dysfunction, patient-ventilator asynchrony and helps early weaning from the ventilator. However, the diversity, complexity, lack of expertise, and associated cost make formulating the appropriate monitoring strategy a challenge for clinicians. Most often, a big amount of data is fed to the clinicians making interpretation difficult. Therefore, it is fundamental for intensivists to be aware of the principle, advantages, and limits of each tool. This analytic review includes a simplified narrative of the commonly used basic and advanced respiratory monitors along with their limits and future prospective.

Airway Pressure Release Ventilation for Acute Respiratory Failure Due to Coronavirus Disease 2019: A Systematic Review and Meta-Analysis.

Objective: To explore the evidence surrounding the use of Airway Pressure Release Ventilation (APRV) in patients with coronavirus disease 2019 (COVID-19). Methods: A Systematic electronic search of PUBMED, EMBASE, and the WHO COVID-19 database. We also searched the grey literature via Google and preprint servers (medRxive and research square). Eligible studies included randomised controlled trials and observational studies comparing APRV to conventional mechanical ventilation (CMV) in adults with acute hypoxemic respiratory failure due to COVID-19 and reporting at least one of the following outcomes; in-hospital mortality, ventilator free days (VFDs), ICU length of stay (LOS), changes in gas exchange parameters, and barotrauma. Two authors independently screened and selected articles for inclusion and extracted data in a pre-specified form. Results: Of 181 articles screened, seven studies (one randomised controlled trial, two cohort studies, and four before-after studies) were included comprising 354 patients. APRV was initiated at a mean of 1.2-13 days after intubation. APRV wasn't associated with improved mortality compared to CMV (relative risk [RR], 1.20; 95% CI 0.70-2.05; I2, 61%) neither better VFDs (ratio of means [RoM], 0.80; 95% CI, 0.52-1.24; I2, 0%) nor ICU LOS (RoM, 1.10; 95% CI, 0.79-1.51; I2, 57%). Compared to CMV, APRV was associated with a 33% increase in PaO2/FiO2 ratio (RoM, 1.33; 95% CI, 1.21-1.48; I2, 29%) and a 9% decrease in PaCO2 (RoM, 1.09; 95% CI, 1.02-1.15; I2, 0%). There was no significant increased risk of barotrauma compared to CMV (RR, 1.55; 95% CI, 0.60-4.00; I2, 0%). Conclusions: In adult patients with COVID-19 requiring mechanical ventilation, APRV is associated with improved gas exchange but not mortality nor VFDs when compared with CMV. The results were limited by high uncertainty given the low quality of the available studies and limited number of patients. Adequately powered and well-designed clinical trials to define the role of APRV in COVID-19 patients are still needed. Registration: PROSPERO; CRD42021291234.

COVID-19 and the Heart: A Systematic Review of Cardiac Autopsies.

Importance: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated cardiac injury has been postulated secondary to several mechanisms. While tissue diagnosis is limited during the acute illness, postmortem studies can help boost our understanding and guide management. Objective: To report the cardiac tissue autopsy findings in coronavirus disease 2019 (COVID-19) decedents. Evidence Review: Articles published in PubMed and Embase reporting postmortem cardiac pathology of COVID-19 decedents till September 2020. We included adult studies excluding preprints. The Joanna Briggs Institute Critical Appraisal Checklist for Case Reports was used to assess quality. We extracted gross and histology data as well as the incidence of myocarditis, cardiac ischemia, thrombosis, and dilatation. We also looked at the reported cause of death (PROSPERO registration CRD42020190898). Findings: Forty-one relevant studies identified including 316 cases. The deceased were mostly male (62%) and elderly (median age, 75; range, 22-97 years). The most common comorbidities were hypertension (48%) and coronary artery disease (33%). Cardiac pathologies contributed to the death of 15 cases. Besides chronic cardiac pathologies, postmortem examination demonstrated cardiac dilatation (20%), acute ischemia (8%), intracardiac thrombi (2.5%), pericardial effusion (2.5%), and myocarditis (1.5%). SARS-CoV-2 was detected within the myocardium of 47% of studied hearts. Conclusions and Relevance: SARS-CoV-2 can invade the heart, but a minority of cases were found to have myocarditis. Cardiac dilatation, ischemia, mural, and microthrombi were the most frequent findings. The systematic review was limited by the small number of cases and the quality of the studies, and there is a need to standardize the cardiac postmortem protocols.

Discharge home from critical care: safety assessment in a resource constrained system.

BACKGROUND: High bed occupancy rates have delayed patient discharges from UK critical care units, especially in acute medical hospitals. As a result, more patients are discharged home directly from critical care (DH). METHODS: In this observational, retrospective study, we quantify the trends in DH from 2013 to 2018, and assess readmission rates and outcome in this group when compared to patients discharged from a ward, from 2014 to 2016. RESULTS: DH rates, as a proportion of critical care admissions, increased every year (2.47% in 2013 to 19.36% in 2018). In 2014-16, the most common admission diagnoses in DH patients were diabetic ketoacidosis (DKA; 35%), drug overdose (12%), seizures (8%) and respiratory failure (8%). DH patients were younger and had shorter critical care stay. Readmission rates in DH patients were comparable to the rest of the hospital. Patients with DKA and seizures were more likely to be readmitted. CONCLUSIONS: Our data suggest that direct home discharge from critical care is increasingly common but safe in selected patient groups.

What is the normal haemodynamic response to passive leg raise? A study of healthy volunteers.

OBJECTIVE: Passive leg raise (PLR) is used as self-fluid challenge to optimise fluid therapy by predicting preload responsiveness. However, there remains uncertainty around the normal haemodynamic response to PLR with resulting difficulties in application and interpretation in emergency care. We aim to define the haemodynamic responses to PLR in spontaneously breathing volunteers using a non-invasive cardiac output monitor, thoracic electrical bioimpedance, TEB (PLR-TEB). METHODS: We recruited healthy volunteers aged 18 or above. Subjects were monitored using TEB in a semirecumbent position, followed by PLR for 3 min. The procedure was repeated after 6 min at the starting position. Correlation between the two PLRs was assessed using Spearman's r (rs). Agreement between the two PLRs was evaluated using Cohen Kappa with responsiveness defined as ≥10% increase in stroke volume. Parametric and non-parametric tests were used as appropriate to evaluate statistical significance of baseline variables between responders and non-responders. RESULTS: We enrolled 50 volunteers, all haemodynamically stable at baseline, of whom 49 completed the study procedure. About half of our subjects were preload responsive. The ∆SV in the two PLRs was correlated (rs=0.68, 95% CI 0.49 to 0.8) with 85% positive concordance. Good agreement was observed with Cohen Kappa of 0.67 (95% CI 0.45 to 0.88). Responders were older and had significantly lower baseline stroke volume and cardiac output. CONCLUSION: Our results suggest that the PLR-TEB is a feasible method in spontaneously breathing volunteers with reasonable reproducibility. The age and baseline stroke volume effect suggests a more complex underlying physiology than commonly appreciated. The fact that half of the volunteers had a positive preload response, against the 10% threshold, leads to questions about how this measurement should be used in emergency care and will help shape future patient studies.

Echodynamics: Interpretation, Limitations, and Clinical Integration!

Echodynamics refers to the use of echocardiography as hemodynamic tool mostly in intensive and acute care settings. It implies a smooth drift from the classic cardiology use to a more critical care adjusted use. A more personalized approach is advocated in critical care, and echo is one way to reach such goal. Correct application necessitates optimum understanding, interpretation, and finally integration into patients' clinical management. As more critical care doctors are advancing from basic focused echo examinations to a more advanced one, this article is trying to underlie many pitfalls of critical care echocardiography in order to guide better practice.

The haemodynamic dilemma in emergency care: Is fluid responsiveness the answer? A systematic review.

BACKGROUND: Fluid therapy is a common and crucial treatment in the emergency department (ED). While fluid responsiveness seems to be a promising method to titrate fluid therapy, the evidence for its value in ED is unclear. We aim to synthesise the existing literature investigating fluid responsiveness in ED. METHODS: MEDLINE, Embase and the Cochrane library were searched for relevant peer-reviewed studies published from 1946 to present. RESULTS: A total of 249 publications were retrieved of which 22 studies underwent full-text review and eight relevant studies were identified. Only 3 studies addressed clinical outcomes - including 2 randomised controlled trials and one feasibility study. Five articles evaluated the diagnostic accuracy of fluid responsiveness techniques in ED. Due to marked heterogeneity, it was not possible to combine results in a meta-analysis. CONCLUSION: High quality, adequately powered outcome studies are still lacking, so the place of fluid responsiveness in ED remains undefined. Future studies should have standardisation of patient groups, the target response and the underpinning theoretic concept of fluid responsiveness. The value of a fluid responsiveness based fluid resuscitation protocol needs to be established in a clinical trial.

Sudden cardiac arrest and coexisting mitral valve prolapse: a case report and literature review.

The aetiology of sudden cardiac arrest can often be identified to underlying cardiac pathology. Mitral valve prolapse is a relatively common valvular pathology with symptoms manifesting with increasing severity of mitral regurgitation (MR). It is unusual for severe MR to be present without symptoms, and there is growing evidence that this subset of patients may be at increased risk of sudden cardiac arrest or death. The difficulty lies in identifying those patients at risk and applying measures that are appropriate to halting progression to cardiac arrest. This article examines the association of mitral valve prolapse with cardiac arrests, the underlying pathophysiological process and the strategies for identifying those at risk.

Acute obstruction of a mechanical aortic valve in a young woman: case report and review of the literature.

UNLABELLED: Acute aortic valve obstruction is a medical and surgical emergency necessitating intensive care unit admission. The differential diagnosis includes thrombosis, pannus formation or vegetations. The diagnosis should be obtained as soon as possible, with possible orientation towards the cause. Different diagnostic modalities exist nowadays. Notably, the transesophageal echocardiography (TEE) offers a diagnosis and a guide for management. Surgical treatment remains of choice despite growing evidence about a benefit of combined thrombolytic and anticoagulation line of management. LEARNING POINTS: Acute management and resuscitation of acute valvular obstruction.Differential diagnosis and role of echo in the diagnosis.Management options.

Predictive value of the heart-type fatty acid-binding protein and the Pulmonary Embolism Severity Index in patients with acute pulmonary embolism in the emergency department.

OBJECTIVES: Heart-type fatty acid-binding protein (h-FABP), sensitive troponins, natriuretic peptides, and clinical scores such as the Pulmonary Embolism Severity Index (PESI) are candidates for risk stratification of patients with acute pulmonary embolism (PE). The aim was to compare their respective prognostic values to predict an adverse outcome at 1 month. METHODS: The authors prospectively included 132 consecutive patients with confirmed acute PE. On admission to the emergency department (ED), plasma concentrations of h-FABP, sensitive cardiac troponin I-Ultra (cTnI-Ultra), and brain natriuretic peptide (BNP) were measured and the PESI calculated in all patients. The combined 30-day outcomes of interest were death, cardiac arrest, mechanical ventilation, use of catecholamines, and recurrence of acute PE. RESULTS: During the first 30 days, 14 (10.6%) patients suffered complications. Among the biomarkers, h-FABP above 6 µg/L was a stronger predictor of an unfavorable outcome (odds ratio [OR] = 17.5, 95% confidence interval [CI] = 4.2 to 73.3) than BNP > 100 pg/mL (OR = 5.7, 95% CI = 1.6 to 20.4) or cTnI-Ultra > 0.05 µg/L (OR = 3.4, 95% CI = 1.1 to 10.9). The PESI classified 83 of 118 patients (70.3%) with favorable outcomes and only one of 14 (7%) with adverse outcomes in low class I or II (OR = 30.8, 95% CI = 3.2 to 299.7). The areas under the receiver operating characteristic (ROC) curves (AUCs) were 0.90 (95% CI = 0.81 to 0.98) for h-FABP, 0.89 (95% CI = 0.82 to 0.96) for PESI, 0.79 (95% CI = 0.67 to 0.90) for BNP, and 0.76 (95% CI = 0.64 to 0.87) for cTnI-Ultra. The combination of h-FABP with PESI was a particularly useful prognostic indicator because none of the 79 patients (59.8%) with h-FABP < 6 ng/mL and PESI class < III had an adverse outcome. CONCLUSIONS: h-FABP and the PESI are superior to BNP and cTnI-Ultra as markers for risk stratification of patients with acute PE. The high sensitivity of their combination identified a large number of low-risk patients in the ED.

CRITICAL CARE ECHO ROUNDS: Haemodynamic instability.

UNLABELLED: The use of echocardiography, whilst well established in cardiology, is a relatively new concept in critical care medicine. However, in recent years echocardiography's potential as both a diagnostic tool and a form of advanced monitoring in the critically ill patient has been increasingly recognised. In this series of Critical Care Echo Rounds, we explore the role of echocardiography in critical illness, beginning here with haemodynamic instability. We discuss the pathophysiology of the shock state, the techniques available to manage haemodynamic compromise, and the unique role which echocardiography plays in this complex process. CASE: A 69-year-old female presents to the emergency department with a fever, confusion and pain on urinating. Her blood pressure on arrival was 70/40, with heart rate of 117 bpm Despite 3 l of i.v. fluid she remained hypotensive. A central venous catheter was inserted and noradrenaline infusion commenced, and she was admitted to the intensive care unit for management of her shock state. At 6 h post admission, she was on high dose of noradrenaline (0.7 µg/kg per min) but blood pressure remained problematic. An echocardiogram was requested to better determine her haemodynamic state.