Impact of cardiac output and alveolar ventilation in estimating ventilation/perfusion mismatch in ARDS using electrical impedance tomography.

INTRODUCTION: Electrical impedance tomography (EIT) can be used to assess ventilation/perfusion (V/Q) mismatch within the lungs. Several methods have been proposed, some of them neglecting the absolute value of alveolar ventilation (VA) and cardiac output (QC). Whether this omission results in acceptable bias is unknown. METHODS: Pixel-level V/Q maps of 25 ARDS patients were computed once considering (absolute V/Q map) and once neglecting (relative V/Q map) the value of QC and VA. Previously published indices of V/Q mismatch were computed using absolute V/Q maps and relative V/Q maps. Indices computed with relative V/Q maps were compared to their counterparts computed using absolute V/Q maps. RESULTS: Among 21 patients with ratio of alveolar ventilation to cardiac output (VA/QC) > 1, relative shunt fraction was significantly higher than absolute shunt fraction [37% (24-66) vs 19% (11-46), respectively, p < 0.001], while relative dead space fraction was significantly lower than absolute dead space fraction [40% (22-49) vs 58% (46-84), respectively, p < 0.001]. Relative wasted ventilation was significantly lower than the absolute wasted ventilation [16% (11-27) vs 29% (19-35), respectively, p < 0.001], while relative wasted perfusion was significantly higher than absolute wasted perfusion [18% (11-23) vs 11% (7-19), respectively, p < 0.001]. The opposite findings were retrieved in the four patients with VA/QC < 1. CONCLUSION: Neglecting cardiac output and alveolar ventilation when assessing V/Q mismatch indices using EIT in ARDS patients results in significant bias, whose direction depends on the VA/QC ratio value.

Necrotizing soft tissue infections in critically ill neutropenic patients: a French multicentre retrospective cohort study.

BACKGROUND: Necrotizing soft tissue infections (NSTIs) are rare life-threatening bacterial infections. Few data are available regarding neutropenic patients with NSTIs. Our objectives were to describe the characteristics and management of neutropenic patients with NSTIs in intensive care units (ICUs). We conducted a retrospective multicentre cohort study in 18 ICUs between 2011 and 2021. Patients admitted with NSTIs and concomitant neutropenia at diagnosis were included and compared to non-neutropenic patients with NSTIs. The relationship between therapeutic interventions and outcomes was assessed using Cox regression and propensity score matching. RESULTS: 76 neutropenic patients were included and compared to 165 non-neutropenic patients. Neutropenic patients were younger (54 ± 14 vs 60 ± 13 years, p = 0.002) and had less lower limb (44.7% vs 70.9%, p < 0.001) and more abdomino-perineal NSTIs (43.4% vs 18.8%, p < 0.001). Enterobacterales and non-fermenting gram-negative bacteria were the most frequently isolated microorganisms in neutropenic patients. In-hospital mortality was significantly higher in neutropenic than in non-neutropenic patients (57.9% vs 28.5%, p < 0.001). Granulocyte colony-stimulating factor (G-CSF) administration was associated with a lower risk of in-hospital mortality in univariable Cox (hazard ratio (HR) = 0.43 95% confidence interval (CI) [0.23-0.82], p = 0.010) and multivariable Cox (adjusted HR = 0.46 95% CI [0.22-0.94], p = 0.033) analyses and after overlap propensity score weighting (odds ratio = 0.25 95% CI [0.09; 0.68], p = 0.006). CONCLUSIONS: Critically ill neutropenic patients with NSTIs present different clinical and microbiological characteristics and are associated with a higher hospital mortality than non-neutropenic patients. G-CSF administration was associated with hospital survival.

Electrocardiographic Changes at the Early Stage of Status Epilepticus: First Insights From the ICTAL Registry.

OBJECTIVES: To describe early electrocardiogram (ECG) abnormalities after status epilepticus (SE) and evaluate their association with 90-day neurological outcomes. DESIGN: Retrospective analysis of a multicenter, national prospective registry between February 2018 and June 2020. SETTING: Sixteen ICUs in France, IctalGroup Research Network. PATIENTS: Adults with available ECG performed less than or equal to 24 hours after the onset of SE and less than or equal to 12 hours after its resolution. INTERVENTION: Double-blinded review of all ECGs was performed by two independent cardiologists. ECGs were categorized as normal/abnormal and then with minor/major early ECG abnormalities according to the Novacode ECG Classification system. MEASUREMENTS AND MAIN RESULTS: Among 155 critically ill patients with SE, early ECG abnormalities were encountered in 145 (93.5%), categorized as major in 91 of 145 (62.8%). In addition to sinus tachycardia, the main abnormalities were in the ST segment (elevation [16.6%] or depression [17.9%]) or negative T waves (42.1%). Major early ECG abnormalities were significantly associated with respiratory distress and sinus tachycardia at the scene and hyperlactatemia at ICU admission. By multivariable analysis, three variables were significantly associated with 90-day poor outcome: age, preexisting ultimately fatal comorbidity, and cerebral insult as the cause of SE. Early major ECG abnormalities were not independently associated with 90-day functional outcome. CONCLUSIONS: In our study, early ECG abnormalities in the acute phase of SE were frequent, often unrecognized and were associated with clinical and biological stigma of hypoxemia. Although they were not independently associated with 90-day functional outcome, ECG changes at the early stage of SE should be systematically evaluated. TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT03457831 .

Driving pressure-guided ventilation decreases the mechanical power compared to predicted body weight-guided ventilation in the Acute Respiratory Distress Syndrome.

BACKGROUND: Whether targeting the driving pressure (∆P) when adjusting the tidal volume in mechanically ventilated patients with the acute respiratory distress syndrome (ARDS) may decrease the risk of ventilator-induced lung injury remains a matter of research. In this study, we assessed the effect of a ∆P-guided ventilation on the mechanical power. METHODS: We prospectively included adult patients with moderate-to-severe ARDS. Positive end expiratory pressure was set by the attending physician and kept constant during the study. Tidal volume was first adjusted to target 6 ml/kg of predicted body weight (PBW-guided ventilation) and subsequently modified within a range from 4 to 10 ml/kg PBW to target a ∆P between 12 and 14 cm H2O. The respiratory rate was then re-adjusted within a range from 12 to 40 breaths/min until EtCO2 returned to its baseline value (∆P-guided ventilation). Mechanical power was computed at each step. RESULTS: Fifty-one patients were included between December 2019 and May 2021. ∆P-guided ventilation was feasible in all but one patient. The ∆P during PBW-guided ventilation was already within the target range of ∆P-guided ventilation in five (10%) patients, above in nine (18%) and below in 36 (72%). The change from PBW- to ∆P-guided ventilation was thus accompanied by an overall increase in tidal volume from 6.1 mL/kg PBW [5.9-6.2] to 7.7 ml/kg PBW [6.2-8.7], while respiratory rate was decreased from 29 breaths/min [26-32] to 21 breaths/min [16-28] (p < 0.001 for all comparisons). ∆P-guided ventilation was accompanied by a significant decrease in mechanical power from 31.5 J/min [28-35.7] to 28.8 J/min [24.6-32.6] (p < 0.001), representing a relative decrease of 7% [0-16]. With ∆P-guided ventilation, the PaO2/FiO2 ratio increased and the ventilatory ratio decreased. CONCLUSION: As compared to a conventional PBW-guided ventilation, a ∆P-guided ventilation strategy targeting a ∆P between 12 and 14 cm H2O required to change the tidal volume in 90% of the patients. Such ∆P-guided ventilation significantly reduced the mechanical power. Whether this physiological observation could be associated with clinical benefit should be assessed in clinical trials.

Multicentre observational status-epilepticus registry: protocol for ICTAL.

INTRODUCTION: Status epilepticus (SE) is a common life-threatening neurological emergency that can cause long-term impairments. Overall outcomes remain poor. Major efforts are required to clarify the epidemiology of SE and the determinants of outcomes, thereby identifying targets for improved management. METHODS AND ANALYSIS: ICTAL Registry is a multicentre open cohort of critically ill patients with convulsive, non-convulsive or psychogenic non-epileptic SE. Observational methods are applied to collect uniform data. The goal of the ICTAL Registry is to collect high-quality information on a large number of patients, thereby allowing elucidation of the pathophysiological mechanisms involved in mortality and morbidity. The registry structure is modular, with a large core data set and the opportunity for research teams to create satellite data sets for observational or interventional studies (eg, cohort multiple randomised controlled trials, cross-sectional studies and short-term and long-term longitudinal outcome studies). The availability of core data will hasten patient recruitment to studies, while also decreasing costs. Importantly, the vast amount of data from a large number of patients will allow valid subgroup analyses, which are expected to identify patient populations requiring specific treatment strategies. The results of the studies will have a broad spectrum of application, particularly given the multidisciplinary approach used by the IctalGroup research network. ETHICS AND DISSEMINATION: The ICTAL Registry protocol was approved by the ethics committee of the French Intensive Care Society (#CE_SRLF 19-68 and 19-68a). Patients or their relatives/proxies received written information to the use of the retrospectively collected and pseudonymised data, in compliance with French law. Prospectively included patients receive written consent form as soon as they recover decision-making competency; if they refuse consent, they are excluded from the registry. Data from the registry will be disseminated via conference presentations and peer-reviewed publications. TRIAL REGISTRATION NUMBER: NCT03457831.

Refractory ineffective triggering during pressure support ventilation: effect of proportional assist ventilation with load-adjustable gain factors.

BACKGROUND: Ineffective triggering is frequent during pressure support ventilation (PSV) and may persist despite ventilator adjustment, leading to refractory asynchrony. We aimed to assess the effect of proportional assist ventilation with load-adjustable gain factors (PAV+) on the occurrence of refractory ineffective triggering. DESIGN: Observational assessment followed by prospective cross-over physiological study. SETTING: Academic medical ICU. PATIENTS: Ineffective triggering was detected during PSV by a twice-daily inspection of the ventilator's screen. The impact of pressure support level (PSL) adjustments on the occurrence of asynchrony was recorded. Patients experiencing refractory ineffective triggering, defined as persisting asynchrony at the lowest tolerated PSL, were included in the physiological study. INTERVENTIONS: Physiological study: Flow, airway, and esophageal pressures were continuously recorded during 10 min under PSV with the lowest tolerated PSL, and then under PAV+ with the gain adjusted to target a muscle pressure between 5 and 10 cmH2O. MEASUREMENTS: Primary endpoint was the comparison of asynchrony index between PSV and PAV+ after PSL and gain adjustments. RESULTS: Among 36 patients identified having ineffective triggering under PSV, 21 (58%) exhibited refractory ineffective triggering. The lowest tolerated PSL was higher in patients with refractory asynchrony as compared to patients with non-refractory ineffective triggering. Twelve out of the 21 patients with refractory ineffective triggering were included in the physiological study. The median lowest tolerated PSL was 17 cmH2O [12-18] with a PEEP of 7 cmH2O [5-8] and FiO2 of 40% [39-42]. The median gain during PAV+ was 73% [65-80]. The asynchrony index was significantly lower during PAV+ than PSV (2.7% [1.0-5.4] vs. 22.7% [10.3-40.1], p < 0.001) and consistently decreased in every patient with PAV+. Esophageal pressure-time product (PTPes) did not significantly differ between the two modes (107 cmH2O/s/min [79-131] under PSV vs. 149 cmH2O/s/min [129-170] under PAV+, p = 0.092), but the proportion of PTPes lost in ineffective triggering was significantly lower with PAV+ (2 cmH2O/s/min [1-6] vs. 8 cmH2O/s/min [3-30], p = 0.012). CONCLUSIONS: Among patients with ineffective triggering under PSV, PSL adjustment failed to eliminate asynchrony in 58% of them (21 of 36 patients). In these patients with refractory ineffective triggering, switching from PSV to PAV+ significantly reduced or even suppressed the incidence of asynchrony.

Continuous positive airway pressure for respiratory support during COVID-19 pandemic: a frugal approach from bench to bedside.

BACKGROUND: We describe a frugal approach (focusing on needs, performance, and costs) to manage a massive influx of COVID-19 patients with acute hypoxemic respiratory failure (AHRF) using the Boussignac valve protected by a filter ("Filter Frugal CPAP", FF-CPAP) in and out the ICU. METHODS: (1) A bench study measured the impact of two filters with different mechanical properties on CPAP performances, and pressures were also measured in patients. (2) Non-ICU healthcare staff working in COVID-19 intermediate care units were trained with a video tutorial posted on a massive open online course. (3) A clinical study assessed the feasibility and safety of using FF-CPAP to maintain oxygenation and manage patients out of the ICU during a massive outbreak. RESULTS: Bench assessments showed that adding a filter did not affect the effective pressure delivered to the patient. The resistive load induced by the filter variably increased the simulated patient's work of breathing (6-34%) needed to sustain the tidal volume, depending on the filter's resistance, respiratory mechanics and basal inspiratory effort. In patients, FF-CPAP achieved pressures similar to those obtained on the bench. The massive training tool provided precious information on the use of Boussignac FF-CPAP on COVID-19 patients. Then 85 COVID-19 patients with ICU admission criteria over a 1-month period were studied upon FF-CPAP initiation for AHRF. FF-CPAP significantly decreased respiratory rate and increased SpO2. Thirty-six (43%) patients presented with respiratory indications for intubation prior to FF-CPAP initiation, and 13 (36%) of them improved without intubation. Overall, 31 patients (36%) improved with FF-CPAP alone and 17 patients (20%) did not require ICU admission. Patients with a respiratory rate > 32 breaths/min upon FF-CPAP initiation had a higher cumulative probability of intubation (p < 0.001 by log-rank test). CONCLUSION: Adding a filter to the Boussignac valve does not affect the delivered pressure but may variably increase the resistive load depending on the filter used. Clinical assessment suggests that FF-CPAP is a frugal solution to provide a ventilatory support and improve oxygenation to numerous patients suffering from AHRF in the context of a massive outbreak.

Electrical impedance tomography to titrate positive end-expiratory pressure in COVID-19 acute respiratory distress syndrome.

RATIONALE: Patients with coronavirus disease-19-related acute respiratory distress syndrome (C-ARDS) could have a specific physiological phenotype as compared with those affected by ARDS from other causes (NC-ARDS). OBJECTIVES: To describe the effect of positive end-expiratory pressure (PEEP) on respiratory mechanics in C-ARDS patients in supine and prone position, and as compared to NC-ARDS. The primary endpoint was the best PEEP defined as the smallest sum of hyperdistension and collapse. METHODS: Seventeen patients with moderate-to-severe C-ARDS were monitored by electrical impedance tomography (EIT) and evaluated during PEEP titration in supine (n = 17) and prone (n = 14) position and compared with 13 NC-ARDS patients investigated by EIT in our department before the COVID-19 pandemic. RESULTS: As compared with NC-ARDS, C-ARDS exhibited a higher median best PEEP (defined using EIT as the smallest sum of hyperdistension and collapse, 12 [9, 12] vs. 9 [6, 9] cmH2O, p < 0.01), more collapse at low PEEP, and less hyperdistension at high PEEP. The median value of the best PEEP was similar in C-ARDS in supine and prone position: 12 [9, 12] vs. 12 [10, 15] cmH2O, p = 0.59. The response to PEEP was also similar in C-ARDS patients with higher vs. lower respiratory system compliance. CONCLUSION: An intermediate PEEP level seems appropriate in half of our C-ARDS patients. There is no solid evidence that compliance at low PEEP could predict the response to PEEP.

Rescue therapy with inhaled nitric oxide and almitrine in COVID-19 patients with severe acute respiratory distress syndrome.

BACKGROUND: In COVID-19 patients with severe acute respiratory distress syndrome (ARDS), the relatively preserved respiratory system compliance despite severe hypoxemia, with specific pulmonary vascular dysfunction, suggests a possible hemodynamic mechanism for VA/Q mismatch, as hypoxic vasoconstriction alteration. This study aimed to evaluate the capacity of inhaled nitric oxide (iNO)-almitrine combination to restore oxygenation in severe COVID-19 ARDS (C-ARDS) patients. METHODS: We conducted a monocentric preliminary pilot study in intubated patients with severe C-ARDS. Respiratory mechanics was assessed after a prone session. Then, patients received iNO (10 ppm) alone and in association with almitrine (10 µg/kg/min) during 30 min in each step. Echocardiographic and blood gases measurements were performed at baseline, during iNO alone, and iNO-almitrine combination. The primary endpoint was the variation of oxygenation (PaO2/FiO2 ratio). RESULTS: Ten severe C-ARDS patients were assessed (7 males and 3 females), with a median age of 60 [52-72] years. Combination of iNO and almitrine outperformed iNO alone for oxygenation improvement. The median of PaO2/FiO2 ratio varied from 102 [89-134] mmHg at baseline, to 124 [108-146] mmHg after iNO (p = 0.13) and 180 [132-206] mmHg after iNO and almitrine (p < 0.01). We found no correlation between the increase in oxygenation caused by iNO-almitrine combination and that caused by proning. CONCLUSION: In this pilot study of severe C-ARDS patients, iNO-almitrine combination was associated with rapid and significant improvement of oxygenation. These findings highlight the role of pulmonary vascular function in COVID-19 pathophysiology.

The Role of Secondary Brain Insults in Status Epilepticus: A Systematic Review.

(1) Background: Little is known about the impact of pathophysiological mechanisms that underlie the enhancement of excitotoxicity and the neuronal consequences of status epilepticus (SE), as well as the clinical consequences of secondary brain insults (SBI) in patients with SE on outcome; (2) Methods: Electronic searches were conducted in May 2020 using Medline via PubMed, Embase, and Google Scholar (#CRD42019139092). Experimental studies of animals or randomized, observational, controlled trials of patients with SE in indexed journals were included. There were no language or date restrictions for the published literature included in this review. Information was extracted on study design, sample size, SBI characteristics, and primary and secondary outcomes, including the timing of evaluation; (3) Results: Among the 2209 articles responding to our inclusion criteria, 56 were included in this systematic review. There are numerous experimental data reporting the deleterious effects associated with each of the SBI in animals exposed to SE. In humans, only the effect of target temperature management in hypothermia (32-34 °C) has been explored. (4) Conclusions: There is little experimental evidence that favors the control of secondary brain insult after SE. Further studies are required to assess the neuroprotective interest of secondary brain insult control after SE in humans.

Epileptic Seizures in Critically Ill Patients: Diagnosis, Management, and Outcomes.

Epileptic seizures in critically ill patients represent a major source of concern, because they are associated with significant mortality and morbidity rates. Despite recent advances that have enabled a better understanding of the global epidemiology of this entity, epileptic seizures in critically ill patients remain associated with a high degree of uncertainty and numerous questions remain unanswered. The present Special Issue aims to invite authors to contribute original research articles as well as review articles related to all aspects of epileptic seizures in critically ill patients, diagnosis, management, and outcomes.

Multidrug-Resistant Acinetobacter baumannii Ventriculostomy-Related Infection, Treated by a Colistin, Tigecycline, and Intraventricular Fibrinolysis.

BACKGROUND: Acinetobacter baumannii meningitis and ventriculitis are difficult issues, because of the low diffusion of antibiotics in the cerebrospinal fluid and bacterial multidrug resistance. The presence of an infected intraventricular hematoma, constituting an equivalent of undrained abscess, may promote biofilm formation and failure of medical treatment. CASE DESCRIPTION: In this case of ventriculostomy-related infection after ventricular hemorrhage, Acinetobacter baumannii was sensitive only to colistin and tigecycline. Despite a combination therapy involving intraventricular injections of colistin, we observed clinical and bacteriologic failure. Therefore, at day 4 of antibiotic therapy, we performed intraventricular fibrinolysis, which dissolved the clot, enabling sterilization of the cerebrospinal fluid after 48 hours. CONCLUSION: This clinical case suggests the usefulness of intraventricular fibrinolysis to lyse the clot and optimize the action of antibiotics.

Comparison of etomidate and sodium thiopental for induction during rapid sequence intubation in convulsive status epilepticus: A retrospective single-center study.

PURPOSE: Few outcome data are available about morbidity associated with endotracheal intubation modalities in critically ill patients with convulsive status epilepticus. We compared etomidate versus sodium thiopental for emergency rapid sequence intubation in patients with out-of-hospital convulsive status epilepticus. METHODS: Patients admitted to our intensive care unit in 2006-2015 were studied retrospectively. The main outcome measure was seizure and/or status epilepticus recurrence within 12 h after rapid sequence intubation. RESULTS: We included 97 patients (60% male; median age, 59 years [IQR, 48-70]). Median time from seizure onset to first antiepileptic drug was 60 min [IQR, 35-90]. Reasons for intubation were coma in 95 (98%), acute respiratory distress in 18 (19%), refractory convulsive status epilepticus in 9 (9%), and shock in 6 (6%) patients; 50 (52%) patients had more than one reason. The hypnotic drugs used were etomidate in 54 (56%) and sodium thiopental in 43 (44%) patients. Seizure and/or status epilepticus recurred in 13 (56%) patients in the etomidate group and 11 patients (44%) in the sodium thiopental group (adjusted common odds ratio [aOR], 0.98; 95%CI, 0.36-2.63; P = 0.97). The two groups were not significantly different for proportions of patients with hemodynamic instability after intubation (aOR, 0.60; 95%CI, 0.23-1.58; P = 0.30) or with difficult endotracheal intubation (OR, 1.28; 95% CI 0.23 to 7.21; P=0.77). CONCLUSIONS: Our findings argue against a difference in seizure and/or status epilepticus recurrences rates between critically ill patients with convulsive status epilepticus given etomidate vs. sodium thiopental as the induction agent for emergency intubation.

Cardiac Arrest in Patients Managed for Convulsive Status Epilepticus: Characteristics, Predictors, and Outcome.

OBJECTIVES: Cardiac arrest is a catastrophic event that may arise during the management of convulsive status epilepticus. We aimed to report the clinical characteristics, outcomes, and early predictors of convulsive status epilepticus-related cardiac arrest. DESIGN: Retrospective multicenter study. SETTING: Seventeen university or university affiliated participating ICUs in France and Belgium. PATIENTS: Consecutive patients admitted to the participating ICUs for management of successfully resuscitated out-of-hospital cardiac arrest complicating the initial management of convulsive status epilepticus between 2000 and 2015. Patients were compared with controls without cardiac arrest identified in a single-center registry of convulsive status epilepticus patients, regarding characteristics, management, and outcome. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We included 49 cases with convulsive status epilepticus-cardiac arrest and 235 controls. In the cases, median time from medical team arrival to cardiac arrest was 25 minutes (interquartile range, 5-85 min). First recorded rhythm was asystole in 25 patients (51%) and pulseless electrical activity in 13 patients (27%). A significantly larger proportion of patients had a favorable 1-year outcome (Glasgow Outcome Scale score of 5) among controls (90/235; 38%) than among cases (10/49; 21%; p = 0.02). By multivariate analysis, independent predictors of cardiac arrest were pulse oximetry less than 97% on scene (odds ratio, 2.66; 95% CI, 1.03-7.26; p = 0.04), drug poisoning as the cause of convulsive status epilepticus (odds ratio, 4.13; 95% CI, 1.27-13.53; p = 0.02), and complications during early management (odds ratio, 11.98; 95% CI, 4.67-34.69; p < 0.0001). Having at least one comorbidity among cardiac, respiratory, and neurologic (other than epilepsy) conditions predicted absence of cardiac arrest (odds ratio, 0.28; 95% CI, 0.10-0.80; p = 0.02). CONCLUSIONS: In patients managed for convulsive status epilepticus, relative hypoxemia, on-scene management complications, and drug poisoning as the cause of convulsive status epilepticus were strong early predictors of cardiac arrest, suggesting areas for improvement.

Duloxetine-related posterior reversible encephalopathy syndrome: A case report.

BACKGROUND: Posterior reversible encephalopathy syndrome (PRES) has well-established links with several drugs. Whether a link also exists with serotonin-norepinephrine reuptake inhibitor such as duloxetine is unclear. METHODS: We report on a patient who developed PRES with a coma and myoclonus related to hypertensive encephalopathy a few days after starting duloxetine treatment. Magnetic resonance imaging was performed and catecholamine metabolites assayed. RESULTS: The patient achieved a full recovery after aggressive antihypertensive therapy and intravenous anticonvulsant therapy. CONCLUSIONS: The clinical history, blood and urinary catecholamine and serotonin levels, and response to treatment strongly suggest that PRES was induced by duloxetine. Duloxetine should be added to the list of causes of PRES.