Defining predictors for successful mechanical ventilation weaning, using a data-mining process and artificial intelligence

Mechanical ventilation weaning within intensive care units (ICU) is a difficult process, while crucial when considering its impact on morbidity and mortality. Failed extubation and prolonged mechanical ventilation both carry a significant risk of adverse events. We aimed to determine predictive factors of extubation success using data-mining and artificial intelligence. A prospective physiological and biomedical signal data warehousing project. A 21-beds medical Intensive Care Unit of a University Hospital. Adult patients undergoing weaning from mechanical ventilation. Hemodynamic and respiratory parameters of mechanically ventilated patients were prospectively collected and combined with clinical outcome data. One hundred and eight patients were included, for 135 spontaneous breathing trials (SBT) allowing to identify physiological parameters either measured before or during the trial and considered as predictive for extubation success. The Early-Warning Score Oxygen (EWSO2) enables to discriminate patients deemed to succeed extubation, at 72-h and 7-days. Cut-off values for EWSO2 (AUC = 0.80; Se = 0.75; Sp = 0.76), mean arterial pressure and heart-rate variability parameters were determined. A predictive model for extubation success was established including body-mass index (BMI) on inclusion, occlusion pressure at 0,1 s. (P0.1) and heart-rate analysis parameters (LF/HF) both measured before SBT, and heart rate during SBT (global performance 62%; 83%). The data-mining process enabled to detect independent predictive factors for extubation success and to develop a dynamic predictive model using artificial intelligence. Such predictive tools may help clinicians to better discriminate patients deemed to succeed extubation and thus improve clinical performance.

Automated Oxygen Titration During CPAP and Noninvasive Ventilation in Healthy Subjects With Induced Hypoxemia

BACKGROUND

Automated oxygen titration to maintain a stable SpO2 has been developed for spontaneously breathing patients but has not been evaluated during CPAP and noninvasive ventilation (NIV).

METHODS

We performed a randomized controlled crossover, double-blind study on 10 healthy subjects with induced hypoxemia during 3 situations: spontaneous breathing with oxygen support, CPAP (5 cm H2O), and NIV (7/3 cm H2O). We conducted in random order 3 dynamic hypoxic challenges of 5 min (FIO2 0.08 ± 0.02, 0.11± 0.02, and 0.14 ± 0.02). For each condition, we compared automated oxygen titration and manual oxygen titration by experienced respiratory therapists (RTs), with the aim to maintain the SpO2 at 94 ± 2%. In addition, we included 2 subjects hospitalized for exacerbation of COPD under NIV and a subject managed after bariatric surgery with CPAP and automated oxygen titration.

RESULTS

The percentage of time in the SpO2 target was higher with automated compared with manual oxygen titration for all conditions, on average 59.6 ± 22.8% compared to 44.3 ± 23.9% (P = .004). Hyperoxemia (SpO2 > 96%) was less frequent with automated titration for each mode of oxygen administration (24.0 ± 24.4% vs 39.1 ± 25.3%, P < .001). During the manual titration periods, the RT made several changes to oxygen flow (5.1 ± 3.3 interventions that lasted 122 ± 70 s/period) compared to none during the automated titration to maintain oxygenation in the targeted SpO2 . Time in the SpO2 target was higher with stable hospitalized subjects in comparison with healthy subjects under dynamic-induced hypoxemia.

CONCLUSIONS

In this proof-of-concept study, automated oxygen titration was used during CPAP and NIV. The performances to maintain the SpO2 target were significantly better compared to manual oxygen titration in the setting of this study protocol. This technology may allow decreasing the number of manual interventions for oxygen titration during CPAP and NIV.

Hydrocortisone in Severe Community-Acquired Pneumonia

BACKGROUND

Whether the antiinflammatory and immunomodulatory effects of glucocorticoids may decrease mortality among patients with severe community-acquired pneumonia is unclear.

METHODS

In this phase 3, multicenter, double-blind, randomized, controlled trial, we assigned adults who had been admitted to the intensive care unit (ICU) for severe community-acquired pneumonia to receive intravenous hydrocortisone (200 mg daily for either 4 or 7 days as determined by clinical improvement, followed by tapering for a total of 8 or 14 days) or to receive placebo. All the patients received standard therapy, including antibiotics and supportive care. The primary outcome was death at 28 days.

RESULTS

A total of 800 patients had undergone randomization when the trial was stopped after the second planned interim analysis. Data from 795 patients were analyzed. By day 28, death had occurred in 25 of 400 patients (6.2%; 95% confidence interval [CI], 3.9 to 8.6) in the hydrocortisone group and in 47 of 395 patients (11.9%; 95% CI, 8.7 to 15.1) in the placebo group (absolute difference, -5.6 percentage points; 95% CI, -9.6 to -1.7; P = 0.006). Among the patients who were not undergoing mechanical ventilation at baseline, endotracheal intubation was performed in 40 of 222 (18.0%) in the hydrocortisone group and in 65 of 220 (29.5%) in the placebo group (hazard ratio, 0.59; 95% CI, 0.40 to 0.86). Among the patients who were not receiving vasopressors at baseline, such therapy was initiated by day 28 in 55 of 359 (15.3%) of the hydrocortisone group and in 86 of 344 (25.0%) in the placebo group (hazard ratio, 0.59; 95% CI, 0.43 to 0.82). The frequencies of hospital-acquired infections and gastrointestinal bleeding were similar in the two groups; patients in the hydrocortisone group received higher daily doses of insulin during the first week of treatment.

CONCLUSIONS

Among patients with severe community-acquired pneumonia being treated in the ICU, those who received hydrocortisone had a lower risk of death by day 28 than those who received placebo. (Funded by the French Ministry of Health; CAPE COD ClinicalTrials.gov number, NCT02517489.).

Accuracy of Multiple Pulse Oximeters in Stable Critically Ill Patients

BACKGROUND

An accurate SpO2 value is critical in order to optimally titrate oxygen delivery to patients and to follow oxygenation guidelines. Limited prospective data exist on real-world performance of pulse oximeters in critically ill patients. The objective of this study was to assess accuracy and bias of the SpO2 values measured by several oximeters in hospitalized subjects.

METHODS

We included stable adults in the ICU with an arterial catheter in place. Main exclusion criteria were poor SpO2 signal and SpO2 > 96%. In each subject, we simultaneously evaluated 4 oximeters: Nonin (Plymouth, Minnesota) embedded in the FreeO2 device (OxyNov, Québec City, Québec, Canada), Masimo (Radical-7, Masimo, Irvine, California), Philips (FAST, Philips, Amsterdam, the Netherlands), and Nellcor (N-600, Medtronic, Minneapolis, Minnesota). Arterial blood gases were drawn and simultaneously each oximeters' SpO2 values were collected. SpO2 values were compared to the reference (arterial oxygen saturation [SaO2 ] value) to determine bias and accuracy. The ability for oximeters to detect hypoxemia and the impact of oximeters on oxygen titration were evaluated.

RESULTS

We included 193 subjects (153 male, mean age 66 y) in whom 211 sets of measurements were performed. The skin pigmentation evaluated by Fitzpatrick scale showed 96.2% of subjects were light skin (types 1 and 2). One oximeter overestimated SaO2 (Philips, +0.9%), whereas the 3 others underestimated SaO2 (Nonin -3.1%, Nellcor -0.3%, Masimo -0.2%). SaO2 was underestimated with Nonin oximeter in 91.3% of the cases, whereas it was overestimated in 55.2% of the cases with Philips oximeter. Moderate hypoxemia (SaO2 86-90% or PaO2 55-60 mm Hg) was detected in 92, 33, 42, and 11% of the cases with Nonin, Nellcor, Masimo, and Philips, respectively.

CONCLUSIONS

We found significant bias and moderate accuracy between the tested oximeters and the arterial blood gases in the studied population. These discrepancies may have important clinical impact on the detection of hypoxemia and management of oxygen therapy.

BMI and pneumonia outcomes in critically ill covid-19 patients: An international multicenter study

OBJECTIVE

Previous studies have unveiled a relationship between the severity of coronavirus disease 2019 (COVID-19) pneumonia and obesity. The aims of this multicenter retrospective cohort study were to disentangle the association of BMI and associated metabolic risk factors (diabetes, hypertension, hyperlipidemia, and current smoking status) in critically ill patients with COVID-19.

METHODS

Patients admitted to intensive care units for COVID-19 in 21 centers (in Europe, Israel, and the United States) were enrolled in this study between February 19, 2020, and May 19, 2020. Primary and secondary outcomes were the need for invasive mechanical ventilation (IMV) and 28-day mortality, respectively.

RESULTS

A total of 1,461 patients were enrolled; the median (interquartile range) age was 64 years (40.9-72.0); 73.2% of patients were male; the median BMI was 28.1 kg/m² (25.4-32.3); a total of 1,080 patients (73.9%) required IMV; and the 28-day mortality estimate was 36.1% (95% CI: 33.0-39.5). An adjusted mixed logistic regression model showed a significant linear relationship between BMI and IMV: odds ratio = 1.27 (95% CI: 1.12-1.45) per 5 kg/m² . An adjusted Cox proportional hazards regression model showed a significant association between BMI and mortality, which was increased only in obesity class III (≥40; hazard ratio = 1.68 [95% CI: 1.06-2.64]).

CONCLUSIONS

In critically ill COVID-19 patients, a linear association between BMI and the need for IMV, independent of other metabolic risk factors, and a nonlinear association between BMI and mortality risk were observed.

Physiological effects of mixed-gas deep sea dives using a closed-circuit rebreather: a field pilot study

PURPOSE

Deep diving using mixed gas with closed-circuit rebreathers (CCRs) is increasingly common. However, data regarding the effects of these dives are still scarce. This preliminary field study aimed at evaluating the acute effects of deep (90-120 msw) mixed-gas CCR bounce dives on lung function in relation with other physiological parameters.

METHODS

Seven divers performed a total of sixteen open-sea CCR dives breathing gas mixture of helium, nitrogen and oxygen (trimix) within four days at 2 depths (90 and 120 msw). Spirometric parameters, SpO₂, body mass, hematocrit, short term heart rate variability (HRV) and critical flicker fusion frequency (CFFF) were measured at rest 60 min before the dive and 120 min after surfacing.

RESULTS

The median [1st-3rd quartile] of the forced vital capacity was lower (84% [76-93] vs 91% [74-107] of predicted values; p = 0.029), whereas FEV1/FVC was higher (98% [95-99] vs 95% [89-99]; p = 0.019) after than before the dives. The other spirometry values and SpO₂ were unchanged. Body mass decreased from 73.5 kg (72.0-89.6) before the dives to 70.0 kg (69.2-85.8) after surfacing (p = 0.001), with no change of hematocrit or CFFT. HRV was increased as indicated by the higher SDNN, RMSSD and pNN50 after than before dives.

CONCLUSION

The present observation represents the first original data regarding the effects of deep repeated CCR dives. The body mass loss and decrease of FVC after bounce dives at depth of about 100 msw may possibly impose an important physiological stress for the divers.

Noninvasive Tidal Volume Measurements, Using a Time-of-Flight Camera, Under High-Flow Nasal Cannula-A Physiological Evaluation, in Healthy Volunteers

OBJECTIVES

The mechanisms of high-flow nasal cannula are still debated but may be mediated by the generation of low positive end-expiratory pressure and a washout of the airway dead space. The aims of this study were to assess the effects of high-flow nasal cannula on tidal volume using a noninvasive method using a time-of-flight camera, under various conditions.

DESIGN

A physiologic evaluation in healthy volunteers.

SETTING

An university hospital ICU.

SUBJECTS

Ten healthy volunteers were included in a physiologic study (CamOpt study, ClinicalTrials.gov identifier: NCT04096183).

INTERVENTIONS

All volunteers were submitted to 12 different conditions (i.e., gas flow [baseline = 0; 30-60 L/min]; mouth [open/closed]; respiratory rate [baseline; baseline + 10 breaths/min]). Tidal volume measurements were performed every minute, during a 6-minute recording period. In all combinations, reference respiratory rate was measured by using chronometric evaluation, over a 30-second period (RRREF), and by using the time-of-flight camera (RRTOF).

MEASUREMENTS AND MAIN RESULTS

Tidal volume increased while increasing gas flow whatever the respiratory rate and mouth condition (p < 0.001). Similar results were observed whatever the experimental conditions (p < 0.01), except one (baseline respiratory rate + 10 breaths/min and mouth closed). Tidal volume increased while decreasing respiratory rate (p < 0.001) and mouth closing (p < 0.05). Proportion of tidal volume greater than 10, 15, and 20 mL/kg changed while increasing the flow. RRTOF was in agreement with RRREF (intraclass correlation coefficient, 0.96), with a low mean bias (0.55 breaths/min) and acceptable deviation.

CONCLUSIONS

Time-of-flight enables to detect tidal volume changes under various conditions of high-flow nasal cannula application. Tidal volume increased significantly while increasing gas flow and mouth closing. Such technique might be useful to monitor the risk of patient self-inflicted lung injury or under assistance.

Accuracy of noncontact surface imaging for tidal volume and respiratory rate measurements in the ICU

Tidal volume monitoring may help minimize lung injury during respiratory assistance. Surface imaging using time-of-flight camera is a new, non-invasive, non-contact, radiation-free, and easy-to-use technique that enables tidal volume and respiratory rate measurements. The objectives of the study were to determine the accuracy of Time-of-Flight volume (VT_TOF) and respiratory rate (RR_TOF) measurements at the bedside, and to validate its application for spontaneously breathing patients under high flow nasal canula. Data analysis was performed within the ReaSTOC data-warehousing project (ClinicalTrials.gov identifier NCT02893462). All data were recorded using standard monitoring devices, and the computerized medical file. Time-of-flight technique used a Kinect V2 (Microsoft, Redmond, WA, USA) to acquire the distance information, based on measuring the phase delay between the emitted light-wave and received backscattered signals. 44 patients (32 under mechanical ventilation; 12 under high-flow nasal canula) were recorded. High correlation (r = 0.84; p < 0.001), with low bias (-1.7 mL) and acceptable deviation (75 mL) was observed between VT_TOF and VT_REF under ventilation. Similar performance was observed for respiratory rate (r = 0.91; p < 0.001; bias < 1b/min; deviation ≤ 5b/min). Measurements were possible for all patients under high-flow nasal canula, detecting overdistension in 4 patients (tidal volume > 8 mL/kg) and low ventilation in 6 patients (tidal volume < 6 mL/kg). Tidal volume monitoring using time-of-flight camera (VT_TOF) is correlated to reference values. Time-of-flight camera enables continuous and non-contact respiratory monitoring under high-flow nasal canula, and enables to detect tidal volume and respiratory rate changes, while modifying flow. It enables respiratory monitoring for spontaneously patients, especially while using high-flow nasal oxygenation.

Automatic oxygen flow titration in spontaneously breathing children: An open-label randomized controlled pilot study

INTRODUCTION

When children require supplemental oxygen due to acute hypoxemic respiratory distress (AHRD), manual control of the oxygen flow is often difficult and time-consuming, and carries the risk of unrecognized hypoxia and hyperoxia. To date, no automatic oxygen titration system has been developed and evaluated in spontaneously breathing children.

METHODS

Children between 1 month and 15 years of age receiving supplemental oxygen due to AHRD were recruited within 24 hours following the onset of the O₂ administration in a French University Department of Paediatrics. Patients were randomized to receive either automated oxygen administration using the FreeO2 device, or conventional manual oxygen administration over a maximum period of 6 hours. Stratification was performed to classify the patients into two age groups: 1 month to 2 years of age and 2 to 15 years of age. The primary outcome was % time spent within the SpO₂ target range (92%-98%).

RESULTS

60 patients (30 infants, 30 children) were randomized and 55 could be analyzed for the primary outcome (28 automated, 27 manual). The automated O₂ delivery using the FreeO2 device significantly increased the time spent within the predefined SpO₂ range (94.6% ± 6% vs 76.3% ± 22%, difference [95% confidence interval {CI}] 18.4 [10.1; 26.7]) with less time spent with hypoxemia (1% ± 1.1% vs 15.1% ± 21.8%, difference [95% CI] -14.4 [-22.2; -6.7]). This difference was greater among (2-15 years of age) children, compared to (1 month-2 years of age) infants.

CONCLUSIONS

The present randomized controlled pilot study indicates that the tested automated closed-loop O₂ titration technology was safe and yielded improved oxygen parameters among spontaneously breathing children. Based on our pilot data, a full randomized controlled trial will be required to verify the potential clinical benefits.

Automatic oxygen administration and weaning in patients following mechanical ventilation

PURPOSE

To evaluate efficacy of FreeO2 device in oxygen weaning of patients after being liberated from mechanical ventilation (MV).

METHODS

Prospective crossover cohort study in patients admitted to ICU and after MV weaning. FreeO2 curves were recorded during constant flow and FreeO2 modes. Oxygenation parameters and O2 consumption were assessed.

RESULTS

Fifty one records were obtained in 51 patients (median age, 62 years, 54.9% had COPD, admission for acute respiratory failure in 96%). NIV was used initially in 68.6%. For a median records duration of 2.04 h, the time spent within target SpO2 range was significantly higher with FreeO2 mode compared to constant O2 flow mode [86.92% (77.11-92.39) vs 43.17% (5.08-75.37); p < 0.001]. Time with hyperoxia was lower with FreeO2 mode: 8.68% (2.96-15.59) vs 38.28% (2.02-86.34). Times with hypoxaemia, and with severe desaturation, were similar. At the end of FreeO2 mode, O2 flow was lower than 1 l/min in 28 patients (54.9%), with a median of 0.99 l/min.

CONCLUSIONS

For the purpose of oxygen weaning in patients recovering from MV, automatic O2 titration with FreeO2 was associated with a substantial reduction in O2 delivery and better oxygenation parameters in comparison with constant O2 flow.

Automated closed-loop versus standard manual oxygen administration after major abdominal or thoracic surgery: an international multicentre randomised controlled study

Introduction

Hypoxaemia and hyperoxaemia may occur after surgery, with related complications. This multicentre randomised trial evaluated the impact of automated closed-loop oxygen administration after high-risk abdominal or thoracic surgeries in terms of optimising the oxygen saturation measured by pulse oximetry time within target range.

Methods

After extubation, patients with an intermediate to high risk of post-operative pulmonary complications were randomised to “standard” or “automated” closed-loop oxygen administration. The primary outcome was the percentage of time within the oxygenation range, during a 3-day frame. The secondary outcomes were the time with hypoxaemia and hyperoxaemia under oxygen.

Results

Among the 200 patients, time within range was higher in the automated group, both initially (≤3 h; 91.4±13.7% versus 40.2±35.1% of time, difference +51.0% (95% CI −42.8–59.2%); p<0.0001) and during the 3-day period (94.0±11.3% versus 62.1±23.3% of time, difference +31.9% (95% CI 26.3–37.4%); p<0.0001). Periods of hypoxaemia were reduced in the automated group (≤3 days; 32.6±57.8 min (1.2±1.9%) versus 370.5±594.3 min (5.0±11.2%), difference −10.2% (95% CI −13.9–−6.6%); p<0.0001), as well as hyperoxaemia under oxygen (≤3 days; 5.1±10.9 min (4.8±11.2%) versus 177.9±277.2 min (27.0±23.8%), difference −22.0% (95% CI −27.6–−16.4%); p<0.0001). Kaplan–Meier analysis depicted a significant difference in terms of hypoxaemia (p=0.01) and severe hypoxaemia (p=0.0003) occurrence between groups in favour of the automated group. 25 patients experienced hypoxaemia for >10% of the entire monitoring time during the 3 days within the standard group, as compared to the automated group (p<0.0001).

Conclusion

Automated closed-loop oxygen administration promotes greater time within the oxygenation target, as compared to standard manual administration, thus reducing the occurrence of hypoxaemia and hyperoxaemia.

Usual and Advanced Monitoring in Patients Receiving Oxygen Therapy

Respiratory monitoring in patients receiving oxygen therapy for acute care is mandatory at the initial stage of in-hospital management given the potential risk of clinical worsening. Although some patients benefit from close monitoring in the ICU, the vast majority of them are managed in general wards with reduced staff and clinical supervision. The objective of monitoring is to detect early clinical deterioration, which may help prevent in-hospital cardiac arrest. In addition to the clinical and usual evaluations (eg, breathing frequency, breathing pattern, oximetry, and oxygen flow requirements), early warning scoring systems have been developed to detect clinical deterioration in acutely ill patients. The monitoring of these scores is recommended for patients receiving oxygen therapy. These scores have several limitations, among which is the absence of oxygen flow evaluation. Manual and intermittent monitoring of these scores in the ward is time-consuming and may not be sufficient to accurately detect deterioration of patient's clinical condition in a timely manner. Automated and continuous monitoring, in addition to clinical evaluation and arterial blood gases analysis, which remain necessary, may improve the detection of clinical worsening in specific patients. Devices that automatically titrate and wean oxygen flow on the basis of [Formula: see text] enable measurement of several major cardiorespiratory parameters (eg, [Formula: see text], oxygen flow, heart rate, breathing frequency, and heart rate variability). The combination of these parameters into new scores is at least as accurate and well-evaluated, and recommended early warning scores and may be useful in monitoring patients receiving oxygen therapy.

Compassionate Use of Remdesivir for Patients with Severe Covid-19

BACKGROUND

Remdesivir, a nucleotide analogue prodrug that inhibits viral RNA polymerases, has shown in vitro activity against SARS-CoV-2.

METHODS

We provided remdesivir on a compassionate-use basis to patients hospitalized with Covid-19, the illness caused by infection with SARS-CoV-2. Patients were those with confirmed SARS-CoV-2 infection who had an oxygen saturation of 94% or less while they were breathing ambient air or who were receiving oxygen support. Patients received a 10-day course of remdesivir, consisting of 200 mg administered intravenously on day 1, followed by 100 mg daily for the remaining 9 days of treatment. This report is based on data from patients who received remdesivir during the period from January 25, 2020, through March 7, 2020, and have clinical data for at least 1 subsequent day.

RESULTS

Of the 61 patients who received at least one dose of remdesivir, data from 8 could not be analyzed (including 7 patients with no post-treatment data and 1 with a dosing error). Of the 53 patients whose data were analyzed, 22 were in the United States, 22 in Europe or Canada, and 9 in Japan. At baseline, 30 patients (57%) were receiving mechanical ventilation and 4 (8%) were receiving extracorporeal membrane oxygenation. During a median follow-up of 18 days, 36 patients (68%) had an improvement in oxygen-support class, including 17 of 30 patients (57%) receiving mechanical ventilation who were extubated. A total of 25 patients (47%) were discharged, and 7 patients (13%) died; mortality was 18% (6 of 34) among patients receiving invasive ventilation and 5% (1 of 19) among those not receiving invasive ventilation.

CONCLUSIONS

In this cohort of patients hospitalized for severe Covid-19 who were treated with compassionate-use remdesivir, clinical improvement was observed in 36 of 53 patients (68%). Measurement of efficacy will require ongoing randomized, placebo-controlled trials of remdesivir therapy. (Funded by Gilead Sciences.).

Photoplethysmographic determination of the respiratory rate in acutely ill patients: validation of a new algorithm and implementation into a biomedical device

Background

Respiratory rate is among the first vital signs to change in deteriorating patients. The aims of this study were to evaluate the accuracy of respiratory rate measurements using a specifically dedicated reflection-mode photoplethysmographic signal analysis in a pathological condition (PPG-RR) and to validate its implementation within medical devices.

Methods

This study is derived from a data mining project, including all consecutive patients admitted to our ICU (ReaSTOC study, ClinicalTrials.gov identifier: NCT02893462). During the evaluation phase of the algorithm, PPG-RR calculations were retrospectively performed on PPG waveforms extracted from the data warehouse and compared with RR reference values. During the prospective phase, PPG-RR calculations were automatically and continuously performed using a dedicated device (FreeO₂, Oxynov, Québec, QC, Canada). In all phases, reference RR was measured continuously using electrical thoracic impedance and chronometric evaluation (Manual-RR) over a 30-s period.

Results

In total, 201 ICU patients’ recordings (SAPS II 51.7 ± 34.6) were analysed during the retrospective evaluation phase, most of them being admitted for a respiratory failure and requiring invasive mechanical ventilation. PPG-RR determination was available in 95.5% cases, similar to reference (22 ± 4 vs. 22 ± 5 c/min, respectively; p = 1), and well correlated with reference values (R = 0.952; p < 0.0001), with a low bias (0.1 b/min) and deviation (± 3.5 b/min). Prospective estimation of the PPG-RR on 30 ICU patients’ recordings was well correlated with the reference method (Manual-RR; r = 0.78; p < 0.001). Comparison of the methods depicted a low bias (0.5 b/min) and acceptable deviation (< ± 5.5 b/min).

Conclusion

According to our results, PPG-RR is an interesting approach for ventilation monitoring, as this technique would make simultaneous monitoring of respiratory rate and arterial oxygen saturation possible, thus minimizing the number of sensors attached to the patient.

Trial registry number ClinicalTrials.gov identifier NCT02893462

Evaluation of emotional excitation during standardized endotracheal intubation in simulated conditions

Objective

To assess how stressful conditions in endotracheal intubation could induct emotional excitation in a population of acute care physicians.

Materials and methods

Two situations were randomly tested: one in standard and easy intubation conditions the other under difficult conditions presumed to induce stress (monitoring alarms, manikin lying on the floor, difficult intubation). Emotional excitation was assessed using several physiological (cardiac patterns, electrodermal activity and eye-tracking) and psycho-cognitive patterns. Auto-evaluations of video recordings and mental workload were performed immediately after simulation.

Results

Significant physiological parameter modifications were observed under the stressful intubation conditions (SDNN 35 ± 15 vs. 42 ± 21; p = 0.035—AVNN 514 ± 94 vs. 548 ± 110; p < 0.0001). Emotional excitation was demonstrated to lead a higher mental workload (NASA-TLX = 39 ± 18 vs. 63 ± 15; p = 0.001), frustration and effort dimensions being its determinant components (p < 0.01). Video recording auto-evaluations depicted significant emotional excitation occurrence under the difficult conditions, with few differences according to the operator’s experience.

Conclusion

This study highlights the fact that a stress condition during ETI on a simulation model leads to an important emotional excitation as compared to the neutral condition.

Automated O2 titration improves exercise capacity in patients with hypercapnic chronic obstructive pulmonary disease: a randomised controlled cross-over trial

Automatically titrated O₂ flows (FreeO₂) was compared with constant O₂ flow on exercise capacity, O₂ saturation and risk of hyperoxia-related hypercapnia in patients with severe COPD with baseline hypercapnia and long-term oxygen therapy (LTOT). Twelve patients were enrolled in a randomised double-blind cross-over study to perform exercise with either FreeO₂ or constant flow. Endurance time (primary outcome) and SpO₂ were both significantly improved with FreeO₂compared with constant flow (p<0.04), although pCO₂ was similar in both conditions. Automated titration of O₂ significantly and clinically improved endurance walking time in patients with severe COPD receiving LTOT, without worsening of pCO₂ TRIAL REGISTRATION NUMBER: Results , NCT01575327.

Compliance with the European trauma guidelines: An observational single centre study

OBJECTIVES

The European trauma guidelines were developed to assist clinicians in the early phase of trauma management to diagnose and treat coagulopathy and bleeding. This study aimed to determine compliance with these European trauma guidelines in a French referral trauma centre.

METHODS

Medical charts of trauma patients with an injury severity score≥16 admitted between January 2013 and December 2014 were reviewed. Compliance with 21 recommendations in the first 24-hours of patient management was assessed.

RESULTS

There were 145 patients with median ISS of 34 [IQR 25-41]. A good level of compliance (i.e. applied in≥80% of patients) was identified for nine recommendations, inconsistent compliance (i.e. applied in 50 to 79% of patients) for six recommendations, including fibrinogen levels at hospital admission and achievement of a target mean arterial blood pressure (MAP)>80mmHg in patients with major bleeding and TBI (55.5%), and poor compliance (i.e. applied in<50% of patients) for another six recommendations. Poorly applied recommendations included early measurement of lactate or base deficit (32%), early administration of tranexamic acid (18%), and achievement of normocapnia in patients with TBI undergoing invasive ventilation (3%).

CONCLUSIONS

In a referral trauma centre, nine of the 21 evaluable recommendations in the European trauma guidelines were applied in≥80% of patients. Early diagnosis and treatment of trauma-related coagulopathy was identified as an area for significant practice improvement. In patients with TBI, efforts should be made to achieve the targeted MAP and to maintain normocapnia.

Tracheotomy in the intensive care unit: Guidelines from a French expert panel: The French Intensive Care Society and the French Society of Anaesthesia and Intensive Care Medicine

Tracheotomy is widely used in intensive care units, albeit with great disparities between medical teams in terms of frequency and modality. Indications and techniques are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of tracheotomy in adult critically ill patients developed using the grading of recommendations assessment, development and evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de réanimation de langue française) and the French Society of Anesthesia and Intensive Care Medicine (Société francaise d'anesthésie réanimation) with the participation of the French Emergency Medicine Association (Société française de médecine d'urgence), the French Society of Otorhinolaryngology. Sixteen experts and two coordinators agreed to consider questions concerning tracheotomy and its practical implementation. Five topics were defined: indications and contraindications for tracheotomy in intensive care, tracheotomy techniques in intensive care, modalities of tracheotomy in intensive care, management of patients undergoing tracheotomy in intensive care, and decannulation in intensive care. The summary made by the experts and the application of GRADE methodology led to the drawing up of 8 formal guidelines, 10 recommendations, and 3 treatment protocols. Among the 8 formal guidelines, 2 have a high level of proof (Grade 1±) and 6 a low level of proof (Grade 2±). For the 10 recommendations, GRADE methodology was not applicable and instead 10 expert opinions were produced.

Tracheotomy in the intensive care unit: guidelines from a French expert panel

Tracheotomy is widely used in intensive care units, albeit with great disparities between medical teams in terms of frequency and modality. Indications and techniques are, however, associated with variable levels of evidence based on inhomogeneous or even contradictory literature. Our aim was to conduct a systematic analysis of the published data in order to provide guidelines. We present herein recommendations for the use of tracheotomy in adult critically ill patients developed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) method. These guidelines were conducted by a group of experts from the French Intensive Care Society (Société de Réanimation de Langue Française) and the French Society of Anesthesia and Intensive Care Medicine (Société Francaise d'Anesthésie Réanimation) with the participation of the French Emergency Medicine Association (Société Française de Médecine d'Urgence), the French Society of Otorhinolaryngology. Sixteen experts and two coordinators agreed to consider questions concerning tracheotomy and its practical implementation. Five topics were defined: indications and contraindications for tracheotomy in intensive care, tracheotomy techniques in intensive care, modalities of tracheotomy in intensive care, management of patients undergoing tracheotomy in intensive care, and decannulation in intensive care. The summary made by the experts and the application of GRADE methodology led to the drawing up of 8 formal guidelines, 10 recommendations, and 3 treatment protocols. Among the 8 formal guidelines, 2 have a high level of proof (Grade 1+/-) and 6 a low level of proof (Grade 2+/-). For the 10 recommendations, GRADE methodology was not applicable and instead 10 expert opinions were produced.

Automaticversusmanual oxygen administration in the emergency department

Oxygen is commonly administered in hospitals, with poor adherence to treatment recommendations.

We conducted a multicentre randomised controlled study in patients admitted to the emergency department requiring O2≥3 L·min−1. Patients were randomised to automated closed-loop or manual O2titration during 3 h. Patients were stratified according to arterial carbon dioxide tension (PaCO2) (hypoxaemicPaCO2≤45 mmHg; or hypercapnicPaCO2>45–≤55 mmHg) and study centre. Arterial oxygen saturation measured by pulse oximetry (SpO2) goals were 92–96% for hypoxaemic, or 88–92% for hypercapnic patients. Primary outcome was % time withinSpO2target. Secondary endpoints were hypoxaemia and hyperoxia prevalence, O2weaning, O2duration and hospital length of stay.

187 patients were randomised (93 automated, 94 manual) and baseline characteristics were similar between the groups. Time within theSpO2target was higher under automated titration (81±21%versus51±30%, p<0.001). Time with hypoxaemia (3±9%versus5±12%, p=0.04) and hyperoxia under O2(4±9%versus22±30%, p<0.001) were lower with automated titration. O2could be weaned at the end of the study in 14.1%versus4.3% patients in the automated and manual titration group, respectively (p<0.001). O2duration during the hospital stay was significantly reduced (5.6±5.4versus7.1±6.3 days, p=0.002).

Automated O2titration in the emergency department improved oxygenation parameters and adherence to guidelines, with potential clinical benefits.

Automated oxygen titration and weaning with FreeO2 in patients with acute exacerbation of COPD: a pilot randomized trial

Introduction

We developed a device (FreeO₂) that automatically adjusts the oxygen flow rates based on patients’ needs, in order to limit hyperoxia and hypoxemia and to automatically wean them from oxygen.

Objective

The aim of this study was to evaluate the feasibility of using FreeO₂ in patients hospitalized in the respiratory ward for an acute exacerbation of COPD.

Methods

We conducted a randomized controlled trial comparing FreeO₂ vs manual oxygen titration in the respiratory ward of a university hospital. We measured the perception of appropriateness of oxygen titration and monitoring in both groups by nurses and attending physicians using a Likert scale. We evaluated the time in the target range of oxygen saturation (SpO₂) as defined for each patient by the attending physician, the time with severe desaturation (SpO₂ <85%), and the time with hyperoxia (SpO₂ >5% above the target). We also recorded length of stay, intensive care unit admissions, and readmission rate. Fifty patients were randomized (25 patients in both groups; mean age: 72±8 years; mean forced expiratory volume in 1 second: 1.00±0.49 L; and mean initial O₂ flow 2.0±1.0 L/min).

Results

Nurses and attending physicians felt that oxygen titration and monitoring were equally appropriate with both O₂ administration systems. The percentage of time within the SpO₂ target was significantly higher with FreeO₂, and the time with severe desaturation and hyperoxia was significantly reduced with FreeO₂. Time from study inclusion to hospital discharge was 5.8±4.4 days with FreeO₂ and 8.4±6.0 days with usual oxygen administration (P=0.051).

Conclusion

FreeO₂ was deemed as an appropriate oxygen administration system by nurses and physicians of a respiratory unit. This system maintained SpO₂ at the target level better than did manual titration and reduced periods of desaturation and hyperoxia. Our results also suggest that FreeO₂ has the potential to reduce the hospital length of stay.

Detection of artifacts on photoplethysmography signals using random distortion testing

In this work, we describe a novel method based on waveform morphology for detecting artifacts in photoplethysmography (PPG) signals and, thus, improve reliability of PPG. By considering inter-individual and measure condition variability, specific parameters are estimated for each record. We introduce a novel metric for comparing pulses, which is the derivative of the correlation coefficient. Then, we propose a detection method based on Random Distortion Testing (RDT), to perform adaptive threasholding for each record. The results show that the proposed method provides pertinent detection of pulses with artifacts. Tested on 104 PPG records, the mean of sensitivity, specificity and accuracy were 84 ± 16%, 83 ± 12% and 83 ± 8%, respectively.

Routine biological tests in self-poisoning patients: results from an observational prospective multicenter study

CONTEXT

Routine biological tests are frequently ordered in self-poisoning patients, but their clinical relevance is poorly studied.

MATERIALS AND METHODS

This is a prospective multicentric observational study conducted in the emergency departments and intensive care units of 5 university and nonuniversity French hospitals. Adult self-poisoning patients without severely altered vital status on admission were prospectively included.

RESULTS

Routine biological test (serum electrolytes and creatinine, liver enzymes, bilirubin, blood cell count, prothrombin time) ordering and results were analyzed. A total of 1027 patients were enrolled (age, 40.2 ± 14 years; women, 61.5%); no patient died during the hospital stay. Benzodiazepine was suspected in more than 70% of cases; 65% (range, 48%-80%) of patients had at least 1 routine biological test performed. At least 1 abnormal test was registered in 23% of these patients. Three factors were associated with abnormal test results: age older than 40 years, male sex, and poisoning with a drug known to alter routine tests (ie, acetaminophen, NSAIDs, metformine, lithium). Depending on these factors, abnormal results ranged from 14% to 48%. Unexpected severe life-threatening conditions were recorded in 6 patients. Only 3 patients were referred to the intensive care unit solely because of abnormal test results.

CONCLUSION

Routine biological tests are commonly prescribed in nonsevere self-poisoning patients. Abnormal results are frequent but their relevance at bedside remains limited.

Can lung ultrasonography predict prone positioning response in acute respiratory distress syndrome patients?

PURPOSE

The purpose was to assess whether lung ultrasonography (L-US) is a useful tool in prediction of prone positioning (PP) oxygenation response in patients with acute respiratory distress syndrome (ARDS).

METHODS

In a prospective study, 19 ARDS patients were included for assessment of PP oxygenation response. The latter was assessed for at least 12 hours 6 different ultrasonography windows were performed on each hemithorax before prone (H0, H2, H12 before return to supine and at H14 (2 hours after return to supine). Patients were classified into 2 groups (responders / non responders) according their oxygenation response to PP. Ultrasonography videos were blindly evaluated by 3 expert clinicians to classify lung regions as "normal", "moderate loss of aeration," "severe loss of aeration," or "lung consolidation." Oxygenation parameters were collected at H0, H2, and H14.

RESULTS

Association of each lung region aspect to PP oxygenation response was compared between the 2 groups. The normal aspect of the anterobasal regions was significantly associated with the oxygenation response (P = .0436), with a positive predictive value equal to or near 100%.

DISCUSSION

Our results demonstrated that a simple and short L-US examination could be a useful tool in prediction of PP oxygenation response in ARDS patients. A normal L-US pattern of both anterobasal lung regions in supine position may predict a significant PaO2/FIO2 ratio improvement.

Bench-test comparison of 26 emergency and transport ventilators

Introduction

Numerous emergency and transport ventilators are commercialized and new generations arise constantly. The aim of this study was to evaluate a large panel of ventilators to allow clinicians to choose a device, taking into account their specificities of use.

Methods

This experimental bench-test took into account general characteristics and technical performances. Performances were assessed under different levels of FIO₂ (100%, 50% or Air-Mix), respiratory mechanics (compliance 30,70,120 mL/cmH₂O; resistance 5,10,20 cmH₂O/mL/s), and levels of leaks (3.5 to 12.5 L/min), using a test lung.

Results

In total 26 emergency and transport ventilators were analyzed and classified into four categories (ICU-like, n = 5; Sophisticated, n = 10; Simple, n = 9; Mass-casualty and military, n = 2). Oxygen consumption (7.1 to 15.8 L/min at F_IO₂ 100%) and the Air-Mix mode (F_IO₂ 45 to 86%) differed from one device to the other. Triggering performance was heterogeneous, but several sophisticated ventilators depicted triggering capabilities as efficient as ICU-like ventilators. Pressurization was not adequate for all devices. At baseline, all the ventilators were able to synchronize, but with variations among respiratory conditions. Leak compensation in most ICU-like and 4/10 sophisticated devices was able to correct at least partially for system leaks, but with variations among ventilators.

Conclusion

Major differences were observed between devices and categories, either in terms of general characteristics or technical reliability, across the spectrum of operation. Huge variability of tidal volume delivery with some devices in response to modifications in respiratory mechanics and F_IO₂ should make clinicians question their use in the clinical setting.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-014-0506-0) contains supplementary material, which is available to authorized users.

[A Serious Game for the prevention of risks in the home]

A Serious Game is a tool based on new technologies. It encompasses the notion of entertainment and learning. It has several purposes and is aimed at professionals as well as the general public. It can be used for educational purposes and integrated into training programmes.

Effect of induced mild hypothermia on two pro-inflammatory cytokines and oxidative parameters during experimental acute sepsis

This study aimed to determine the effect of induced mild hypothermia (34°C) on the production of two cytokines (interleukin (IL-6) and tumor necrosis factor (TNF)alpha) and reactive nitrogen and oxygen species in plasma and the heart of acutely septic rats. After anesthesia and in conditions of normothermia (38°C) or mild hypothermia (34°C), acute sepsis was induced by cecal ligation and perforation. For each temperature three groups were formed: (1) baseline (blood sample collected at T0 hour), (2) sham (blood sample at T4 hours) and (3) septic (blood sample at T4 hours). At either temperature sepsis induced a significant increase in plasma IL-6, TNF-alpha and HO• concentration, compared with the sham groups (P≤0.016). Compared with the normothermic septic group, septic rats exposed to mild hypothermia showed a mild decrease in TNF-alpha concentration (104±50 pg/ml vs. 215±114 pg/ml; P>0.05) and a significant decrease in IL-6 (1131±402 pg/ml vs. 2494±691 pg/ml, P=0.038). At either temperature sepsis induced no enhancement within the heart of lipoperoxidation (malondialdehyde content) or antioxidant activities (superoxide dismutase and catalase). In conclusion, during acute sepsis, induced mild hypothermia appears to reduce some pro-inflammatory and oxidative responses. This may, in part, explain the beneficial effect of hypothermia on survival duration of septic rats.

Comparison of usual and alternative methods to measure height in mechanically ventilated patients: potential impact on protective ventilation

BACKGROUND

Protective ventilation implementation requires the calculation of predicted body weight (PBW), determined by a formula based on gender and height. Consequently, height inaccuracy may be a limiting factor to correctly set tidal volumes. The objective of this study was to evaluate the accuracy of different methods in measuring heights in mechanically ventilated patients.

METHODS

Before cardiac surgery, actual height was measured with a height gauge while subjects were standing upright (reference method); the height was also estimated by alternative methods based on lower leg and forearm measurements. After cardiac surgery, upon ICU admission, a subject's height was visually estimated by a clinician and then measured with a tape measure while the subject was supine and undergoing mechanical ventilation.

RESULTS

One hundred subjects (75 men, 25 women) were prospectively included. Mean PBW was 61.0 ± 9.7 kg, and mean actual weight was 30.3% higher. In comparison with the reference method, estimating the height visually and using the tape measure were less accurate than both lower leg and forearm measurements. Errors above 10% in calculating the PBW were present in 25 and 40 subjects when the tape measure or visual estimation of height was used in the formula, respectively. With lower leg and forearm measurements, 15 subjects had errors above 10% (P < .001).

CONCLUSIONS

Our results demonstrate that significant variability exists between the different methods used to measure height in bedridden patients on mechanical ventilation. Alternative methods based on lower leg and forearm measurements are potentially interesting solutions to facilitate the accurate application of protective ventilation.

Evaluation of manual and automatic manually triggered ventilation performance and ergonomics using a simulation model

BACKGROUND

In the absence of endotracheal intubation, the manual bag-valve-mask (BVM) is the most frequently used ventilation technique during resuscitation. The efficiency of other devices has been poorly studied. The bench-test study described here was designed to evaluate the effectiveness of an automatic, manually triggered system, and to compare it with manual BVM ventilation.

METHODS

A respiratory system bench model was assembled using a lung simulator connected to a manikin to simulate a patient with unprotected airways. Fifty health-care providers from different professional groups (emergency physicians, residents, advanced paramedics, nurses, and paramedics; n = 10 per group) evaluated manual BVM ventilation, and compared it with an automatic manually triggered device (EasyCPR). Three pathological situations were simulated (restrictive, obstructive, normal). Standard ventilation parameters were recorded; the ergonomics of the system were assessed by the health-care professionals using a standard numerical scale once the recordings were completed.

RESULTS

The tidal volume fell within the standard range (400-600 mL) for 25.6% of breaths (0.6-45 breaths) using manual BVM ventilation, and for 28.6% of breaths (0.3-80 breaths) using the automatic manually triggered device (EasyCPR) (P < .0002). Peak inspiratory airway pressure was lower using the automatic manually triggered device (EasyCPR) (10.6 ± 5 vs 15.9 ± 10 cm H2O, P < .001). The ventilation rate fell consistently within the guidelines, in the case of the automatic manually triggered device (EasyCPR) only (10.3 ± 2 vs 17.6 ± 6, P < .001). Significant pulmonary overdistention was observed when using the manual BVM device during the normal and obstructive sequences. The nurses and paramedics considered the ergonomics of the automatic manually triggered device (EasyCPR) to be better than those of the manual device.

CONCLUSIONS

The use of an automatic manually triggered device may improve ventilation efficiency and decrease the risk of pulmonary overdistention, while decreasing the ventilation rate.

Determination of the learning curve for ultrasound-guided jugular central venous catheter placement

PURPOSE

Use of ultrasound (US) when introducing central venous catheters (CVC) may improve success rates, reduce the number of needle punctures, and decrease complication rates, but has been hampered by supposed difficulty in learning how to perform the technique. This study describes the learning curve for US-guided jugular CVC placement after a training program.

METHODS

After an initial slide presentation and a video, intensivists who had not previously used US for CVC placement were evaluated qualitatively for US set up (score S1) and technical skills (score S2). Quantitative measures included durations of different components of the procedure (T1, time from entry of the US into the patient's room to sterile dressing of the intensivist; T2, time needed for sterile drapes, venous line preparation, and sterile sheath placement; T3, time from skin puncture to venous flashback; T4, time from guide insertion to dressing; T(tot), total duration of the procedure); number of skin punctures; and a difficulty score allocated by the intensivist.

RESULTS

We performed 150 evaluations of 30 intensivists: 50% had no prior experience of CVC placement and 50% no prior US experience. Maximal S1 and S2 scores were obtained with the fourth and eighth placement procedures, respectively. T1 and T2 did not change with ongoing training (5 and 8 min, respectively), but T3 and T4 decreased, from 5 min (first procedure) to less than 1 min (seventh procedure), and from 10 min (first procedure) to 7 min (sixth procedure), respectively. T(tot) decreased from 34 to 21 min at the eighth procedure. The number of skin punctures and the difficulty score decreased rapidly with the number of evaluations.

CONCLUSIONS

Our study demonstrates that skills in US-guided CVC placement can easily be acquired with training.

Impact of humidification and nebulization during expiratory limb protection: an experimental bench study

BACKGROUND

Different filtering devices are used during mechanical ventilation to avoid dysfunction of flow and pressure transducers or for airborne microorganisms containment. Water condensates, resulting from the use of humidifiers, but also residual nebulization particles may have a major influence on expiratory limb resistance.

OBJECTIVES

To evaluate the influence of nebulization and active humidification on the resistance of expiratory filters.

METHODS

A respiratory system analog was constructed using a test lung, an ICU ventilator, heated humidifiers, and a piezoelectric nebulizer. Humidifiers were connected to different types of circuits (unheated, mono-heated, new-generation and old-generation bi-heated). Five filter types were evaluated: electrostatic, heat-and-moisture exchanger, standard, specific, and internal heated high-efficiency particulate air [HEPA] filter. Baseline characteristics were obtained from each dry filter. Differential pressure measurements were carried out after 24 hours of continuous in vitro use for each condition, and after 24 hours of use with an old-generation bi-heated circuit without nebulization.

RESULTS

While using unheated circuits, measurements had to be interrupted before 24 hours for all the filtering devices except the internal heated HEPA filter. The heat-and-moisture exchangers occluded before 24 hours with the unheated and mono-heated circuits. The circuit type, nebulization practice, and duration of use did not influence the internal heated HEPA filter resistance.

CONCLUSION

Expiratory limb filtration is likely to induce several major adverse events. Expiratory filter resistance increase is due mainly to the humidification circuit type, rather than to nebulization. If filtration is mandatory while using an unheated circuit, a dedicated filter should be used for ≤ 24 hours, or a heated HEPA for a longer duration.

The semi-seated position slightly reduces the effort to breathe during difficult weaning

PURPOSE

The influence of posture on breathing effort in patients with difficult weaning is unknown. We hypothesized that posture could modulate the breathing effort in difficult-to-wean patients.

METHODS

A prospective, crossover, physiologic study was performed in 24 intubated patients breathing with pressure support who had already failed a spontaneous breathing trial or an extubation episode. Their median duration of mechanical ventilation before measurements was 25 days. Breathing pattern, occlusion pressure (P (0.1)), intrinsic PEEP (PEEP(i)), and inspiratory muscle effort evaluated by the pressure-time product of the respiratory muscles and the work of breathing were measured during three postures: the seated position in bed (90°LD), simulating the position in a chair, the semi-seated (45°), and the supine (0°) positions consecutively applied in a random order. A comfort score was obtained in 17 cooperative patients. The influence of position on chest wall compliance was measured in another group of 11 sedated patients.

RESULTS

The 45° position was associated with the lowest levels of effort (p ≤ 0.01) and occlusion pressure (p < 0.05), and tended to be more often comfortable. Respiratory effort was the lowest at 45° in 18/24 patients. PEEP(i) and PEEP(i)-related work were slightly higher in the supine position (p ≤ 0.01), whereas respiratory effort, heart rate, and P (0.1) values were increased in the seated position (p < 0.05).

CONCLUSION

A 45° position helps to unload the respiratory muscles, moderately reduces PEEP(i), and is often considered as comfortable. The semi-seated position may help the weaning process in ventilator-dependent patients.

[Current trends in plasma transfusion for patients with severe hemorrhage]

Recent changes in plasma transfusion practices for severe hemorrhage are largely related to the recognition of an early endogenous coagulopathy associated with traumatic injury. Observational and mostly retrospective data suggest improved survival rates with high-dose plasma therapy, up to a 1:1 ratio of fresh frozen plasma to packed red blood cells, but the quality of evidence is limited. Putting it into practice raises many issues (early identification of patients at risk of massive bleeding, extrapolation to non-trauma settings, alternative or adjunctive treatments, among others) that are discussed in this brief review.

Noninvasive ventilation and weaning in patients with chronic hypercapnic respiratory failure: a randomized multicenter trial

RATIONALE

The use of noninvasive ventilation (NIV) as an early weaning/extubation technique from mechanical ventilation remains controversial.

OBJECTIVES

To investigate NIV effectiveness as an early weaning/extubation technique in difficult-to-wean patients with chronic hypercapnic respiratory failure (CHRF).

METHODS

In 13 intensive care units, 208 patients with CHRF intubated for acute respiratory failure (ARF) who failed a first spontaneous breathing trial were randomly assigned to three groups: conventional invasive weaning group (n = 69), extubation followed by standard oxygen therapy (n = 70), or NIV (n = 69). NIV was permitted as rescue therapy for both non-NIV groups if postextubation ARF occurred. Primary endpoint was reintubation within 7 days after extubation. Secondary endpoints were: occurrence of postextubation ARF or death within 7 days after extubation, use of rescue postextubation NIV, weaning time, and patient outcomes.

MEASUREMENTS AND MAIN RESULTS

Reintubation rates were 30, 37, and 32% for invasive weaning, oxygen-therapy, and NIV groups, respectively (P = 0.654). Weaning failure rates, including postextubation ARF, were 54, 71, and 33%, respectively (P < 0.001). Rescue NIV success rates for invasive and oxygen-therapy groups were 45 and 58%, respectively (P = 0.386). By design, intubation duration was 1.5 days longer for the invasive group than in the two others. Apart from a longer weaning time in NIV than in invasive group (2.5 vs. 1.5 d; P = 0.033), no significant outcome difference was observed between groups.

CONCLUSIONS

No difference was found in the reintubation rate between the three weaning strategies. NIV decreases the intubation duration and may improve the weaning results in difficult-to-wean patients with CHRF by reducing the risk of postextubation ARF. The benefit of rescue NIV in these patients deserves confirmation.