[Show abstract][Hide abstract] ABSTRACT: Reduction of breathing variability is associated with adverse outcome. During mechanical ventilation, the variability of ventilatory pressure is dependent on the ventilatory mode. During neurally adjusted ventilatory assist (NAVA), the support is proportional to electrical activity of the diaphragm (EAdi), which reflects the respiratory center output. The variability of EAdi is, therefore, translated into a similar variability in pressures. Contrastingly, conventional ventilatory modes deliver less variable pressures. The impact of the mode on the patient's own respiratory drive is less clear. This study aims to compare the impact of NAVA, pressure-controlled ventilation (PCV), and pressure support ventilation (PSV) on the respiratory drive patterns in infants. We hypothesized that on NAVA, EAdi variability resembles most of the endogenous respiratory drive pattern seen in a control group.
Electrical activity of the diaphragm was continuously recorded in 10 infants ventilated successively on NAVA (5 h), PCV (30 min), and PSV (30 min). During the last 10 min of each period, the EAdi variability pattern was assessed using non-rhythmic to rhythmic (NRR) index. These variability profiles were compared to the pattern of a control group of 11 spontaneously breathing and non-intubated infants.
In control infants, NRR was higher as compared to mechanically ventilated infants (p < 0.001), and NRR pattern was relatively stable over time. While the temporal stability of NRR was similar in NAVA and controls, the NRR profile was less stable during PCV. PSV exhibited an intermediary pattern.
Mechanical ventilation impacts the breathing variability in infants. NAVA produces EAdi pattern resembling most that of control infants. NRR can be used to characterize respiratory variability in infants. Larger prospective studies are necessary to understand the differential impact of the ventilatory modes on the cardio-respiratory variability and to study their impact on clinical outcomes.
[Show abstract][Hide abstract] ABSTRACT: This paper presents a computer-aided diagnosis system (CAD) for the assessment of Acute Respiratory Distress Syndrome (ARDS) from chest radiographs. Our method consists in automatically extracting intercostal patches from chest radiographs belonging to the test database using semiautomatic segmentation method of the ribs. Statistical and spectral features are computed from each patch then a method of feature transformation is applied using the Linear Discriminant Analysis (LDA). A training database of 321 patches was classified by an expert in two classes, a class of normal patches and a class of abnormal patches. Patches belonging to the test database are then classified using the SVM classifier. Finally, the rate of abnormal patches is calculated for each quadrant to decide if the chest radiograph presents an ARDS. The method has been evaluated on 90 radiographs where 53 images present ARDS. The results show a sensitivity of 90.6% at a specificity of 86.5%.
Computers in Biology and Medicine 09/2014; · 1.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: PURPOSE: Diaphragm function should be monitored in critically ill patients, as full ventilatory support rapidly induces diaphragm atrophy. Monitoring the electrical activity of the diaphragm (EAdi) may help assess the level of diaphragm activity, but such monitoring results are difficult to interpret because reference values are lacking. The aim of this study was to describe EAdi values in critically ill children during a stay in the pediatric intensive care unit (PICU), from the acute to recovery phases, and to assess the impact of ventilatory support on EAdi.
METHODS: This was a prospective longitudinal observational study of children requiring mechanical ventilation for ≥24 h. EAdi was recorded using a validated method in the acute phase, before extubation, after extubation, and before PICU discharge.
RESULTS: Fifty-five critically ill children were enrolled in the study. Median maximum inspiratory EAdi (EAdimax) during mechanical ventilation was 3.6 [interquartile range (IQR) 1.2-7.6] μV in the acute phase and 4.8 (IQR 2.0-10.7) μV in the pre-extubation phase. Periods of diaphragm inactivity (with no detectable inspiratory EAdi) were frequent during conventional ventilation, even with a low level of support. EAdimax in spontaneous ventilation was 15.4 (IQR 7.4-20.7) μV shortly after extubation and 12.6 (IQR 8.1-21.3) μV before PICU discharge. The difference in EAdimax between mechanical ventilation and post-extubation periods was significant (p < 0.001). Patients intubated mainly because of a lung pathology exhibited higher EAdi (p < 0.01), with a similar temporal increase.
CONCLUSIONS: This is the first systematic description of EAdi evolution in children during their stay in the PICU. In our patient cohort, diaphragm activity was frequently low in conventional ventilation, suggesting that overassistance or oversedation is common in clinical practice. EAdi monitoring appears to be a helpful tool to detect such situations.
Intensive Care Medicine 08/2014; · 5.54 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The point prevalence methodology is a valuable epidemiological study design that can optimize patient enrollment, prospectively gather individual-level data, and measure practice variability across a large number of geographic regions and healthcare settings. The objective of this article is to review the design, implementation, and analysis of recent point prevalence studies investigating the global epidemiology of pediatric critical illness.
Literature review and primary datasets.
Multicenter, international point prevalence studies performed in PICUs since 2007.
Study topic, number of sites, number of study days, patients screened, prevalence of disease, use of specified therapies, and outcomes.
Since 2007, five-point prevalence studies have been performed on acute lung injury, neurologic disease, thromboprophylaxis, fluid resuscitation, and sepsis in PICUs. These studies were performed in 59-120 sites in 7-28 countries. All studies accounted for seasonal variation in pediatric disease by collecting data over multiple study days. Studies screened up to 6,317 patients and reported data on prevalence and therapeutic variability. Three studies also reported short-term outcomes, a valuable but atypical data element in point prevalence studies. Using these five studies as examples, the advantages and disadvantages and approach to designing, implementing, and analyzing point prevalence studies are reviewed.
Point prevalence studies in pediatric critical care can efficiently provide valuable insight on the global epidemiology of disease and practice patterns for critically ill children.
Pediatric Critical Care Medicine 04/2014; · 2.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Supportive care as a bridge to transplant or recovery remains challenging in children suffering from acute liver failure (ALF). We report our experience in children using the Molecular Absorbent Recirculating System (MARS®).
Retrospective data from children receiving therapy using MARS® from October 2009 to October 2012 were included in this single-center retrospective study. Patient characteristics, clinical presentation and complications of ALF, clinical and biological data before and after each MARS® session, technical modalities and adverse events were recorded.
A total of six children underwent 17 MARS® sessions during the study period. Two adolescents were treated with the adult filter MARSFLUX® and four infants were treated with the MiniMARS® filter. The mean PEdiatric Logistic Dysfunction (PELOD) score at admission was 19 (range 11-33). All patients were mechanically ventilated, and four had acute kidney injury. The neurological course improved in one case, judged as stable in two cases and worsened in one case; data were unavailable in two cases. Mean serum ammonia levels decreased significantly following treatment with MARS® from an initial 89 ± 29 to 58 ± 35 mcmol/L (p = 0.02). No other significant biological improvement was observed. Hemodynamic status improved/remained unchanged in the adolescent group, but in the infants four of the seven sessions were poorly tolerated and two sessions were aborted. Three patients died, two were successfully transplanted and one recovered without transplantation.
In our experience, treatment with MARS® is associated with encouraging results in adolescents, but it needs modification for very sick infants to improve tolerance.
[Show abstract][Hide abstract] ABSTRACT: The aim of this survey was to determine North American and European pediatric intensivists' knowledge and stated practice in the management of children with acute respiratory distress syndrome with regard to mechanical ventilation settings; blood gas and SO2 targets; and use of adjunctive treatments at sites where actual practice had just been assessed.
A survey using three case scenarios to assess mechanical ventilation strategies used in children with acute respiratory distress syndrome was sent out toward the end of data collection to all centers participating in the Pediatric Acute Lung Injury Mechanical Ventilation study (59 PICUs in 12 countries). For each case scenario, intensivists were asked to report the optimal mechanical ventilation parameters; blood gas and SO2 acceptable targets; and threshold for considering high-frequency oscillatory ventilation, and other adjunctive treatments.
Fifty-four pediatric intensivists, representing 47 centers from 11 countries.
Many pediatric intensivists reported using a tidal volume of 5-8 mL/kg (88-96%) and none reported using a tidal volume above 10 mL/kg. On average, the upper threshold of positive inspiratory pressure at which intensivists would consider another ventilation mode was 35 cm H2O. Permissive hypercapnia and mild hypoxemia (SO2 as low as 88%) was considered tolerable by many pediatric intensivists. Finally, a large proportion of pediatric intensivists reported they would use adjunctive treatments (nitric oxide, prone position, extracorporeal membrane oxygenation, surfactant, steroids, β-agonists) if the patient's condition worsened.
Although in theory, many pediatric intensivists agreed with adult recommendations to ventilate with lower tidal volumes and pressure limits, the Pediatric Acute Lung Injury Mechanical Ventilation data revealed that over 25% of pediatric patients with acute lung injury/acute respiratory distress syndrome at many of these practice sites were ventilated with tidal volumes above 10 mL/kg and that high positive inspiratory pressure levels (> 35 mm Hg) were often tolerated.
Pediatric Critical Care Medicine 07/2013; · 2.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Automated closed loop systems may improve adaptation of the mechanical support to a patient's ventilatory needs and facilitate systematic and early recognition of their ability to breathe spontaneously and the potential for discontinuation of ventilation. OBJECTIVES: To compare the duration of weaning from mechanical ventilation for critically ill ventilated adults and children when managed with automated closed loop systems versus non-automated strategies. Secondary objectives were to determine differences in duration of ventilation, intensive care unit (ICU) and hospital length of stay (LOS), mortality, and adverse events. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 2); MEDLINE (OvidSP) (1948 to August 2011); EMBASE (OvidSP) (1980 to August 2011); CINAHL (EBSCOhost) (1982 to August 2011); and the Latin American and Caribbean Health Sciences Literature (LILACS). In addition we received and reviewed auto-alerts for our search strategy in MEDLINE, EMBASE, and CINAHL up to August 2012. Relevant published reviews were sought using the Database of Abstracts of Reviews of Effects (DARE) and the Health Technology Assessment Database (HTA Database). We also searched the Web of Science Proceedings; conference proceedings; trial registration websites; and reference lists of relevant articles. SELECTION CRITERIA: We included randomized controlled trials comparing automated closed loop ventilator applications to non-automated weaning strategies including non-protocolized usual care and protocolized weaning in patients over four weeks of age receiving invasive mechanical ventilation in an intensive care unit (ICU). DATA COLLECTION AND ANALYSIS: Two authors independently extracted study data and assessed risk of bias. We combined data into forest plots using random-effects modelling. Subgroup and sensitivity analyses were conducted according to a priori criteria. MAIN RESULTS: Pooled data from 15 eligible trials (14 adult, one paediatric) totalling 1173 participants (1143 adults, 30 children) indicated that automated closed loop systems reduced the geometric mean duration of weaning by 32% (95% CI 19% to 46%, P = 0.002), however heterogeneity was substantial (I(2) = 89%, P < 0.00001). Reduced weaning duration was found with mixed or medical ICU populations (43%, 95% CI 8% to 65%, P = 0.02) and Smartcare/PS™ (31%, 95% CI 7% to 49%, P = 0.02) but not in surgical populations or using other systems. Automated closed loop systems reduced the duration of ventilation (17%, 95% CI 8% to 26%) and ICU length of stay (LOS) (11%, 95% CI 0% to 21%). There was no difference in mortality rates or hospital LOS. Overall the quality of evidence was high with the majority of trials rated as low risk. AUTHORS' CONCLUSIONS: Automated closed loop systems may result in reduced duration of weaning, ventilation, and ICU stay. Reductions are more likely to occur in mixed or medical ICU populations. Due to the lack of, or limited, evidence on automated systems other than Smartcare/PS™ and Adaptive Support Ventilation no conclusions can be drawn regarding their influence on these outcomes. Due to substantial heterogeneity in trials there is a need for an adequately powered, high quality, multi-centre randomized controlled trial in adults that excludes 'simple to wean' patients. There is a pressing need for further technological development and research in the paediatric population.
[Show abstract][Hide abstract] ABSTRACT: Canada was one of the first countries affected by the 2009 influenza H1N1 pandemic with two waves - one from May to June and one from October to December. The 2009 influenza H1N1 pandemic had many unique features when compared with seasonal influenza, including the following: more than half of the affected people were children; asthma was the most significant risk factor for hospital admission; and Aboriginal and pregnant women had a higher risk of hospital admission and complications. Antiviral therapy was widely used but data did not show any effect on the pediatric population. Outbreak spread was possibly promoted from child-child and child-adult contact, and therefore the vaccination campaign targeted the pediatric population and achieved good coverage among young children (57%). Vaccination efficacy was difficult to test because of the vaccination delay. Improvement in models of prevention and treatment are urgently needed to prepare for the possible future pandemics.
[Show abstract][Hide abstract] ABSTRACT: Mechanical ventilation is a sophisticated technique with very narrow therapeutic ranges i.e. highly efficient and able to keep alive the most severe patients, but with considerable side effects and unwanted complications if not properly and timely used. Computerized protocols, closed loop systems, decision support, all terms which need to be defined, may help making mechanical ventilation safer and more efficient. The present paper will provide a short overview on technical and engineering considerations regarding closed loop controlled ventilation as well as tangible clinical evidences supporting the previous statement.
International Journal of Clinical Monitoring and Computing 04/2013;
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE:: To describe the planned aims and methodology of the Pediatric Acute Lung Injury Consensus Conference. DESIGN:: Consensus conference of experts in pediatric acute lung injury. METHODS:: A panel of 26 experts in pediatric acute lung injury will meet over the course of one year to develop a better taxonomy to define pediatric acute lung injury, specifically predisposing factors, etiology, and pathophysiology. A modified Delphi approach that emphasizes strong professional agreement will be utilized. RESULTS:: The Pediatric Acute Lung Injury Consensus Conference will aim for consensus development on the following topics related to pediatric acute lung injury: 1) definition, incidence, and epidemiology; 2) comorbidities and severity; 3) ventilatory support; 4) pulmonary-specific ancillary treatment; 5) nonpulmonary treatment; 6) monitoring; 7) noninvasive support and ventilation; 8) extracorporeal support; and 9) morbidity and long-term outcomes. CONCLUSIONS:: The importance of this effort for improving care and guiding future research in pediatric acute lung injury is clear. Despite the many epidemiologic, interventional, and outcome studies undertaken by pediatric intensivists worldwide, our understanding of this disease process is limited, and morbidity and mortality remain unacceptably high. By consolidating the knowledge and expertise of the leaders of the field of pediatric acute lung injury, we hope to develop a framework for future progress.
Pediatric Critical Care Medicine 02/2013; · 2.35 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT PURPOSE: Although secondary infections are recognized as a cause of morbidity and mortality in seasonal influenza, their frequency, characteristics and associated clinical outcomes in Influenza A (H1N1)-related critical illness are unknown. METHODS: In a prospective cohort of adult patients admitted to Canadian Intensive Care Units (ICUs) with H1N1 infection, the frequency and associated clinical outcomes of prevalent (culture taken within 72 hours of ICU admission) and ICU-acquired (culture taken after 72 hours from ICU admission) positive bacterial cultures were determined. RESULTS: Among 681 patients the mean age was 47.9 years (standard deviation [SD] 15.1), APACHE II was 21.0 (9.9) and 573 (84.0%) were invasively mechanical ventilated (MV). Positive cultures were obtained in 259 (38.0 %): 77 (29.7%) prevalent; 115 (44.4%) ICU-acquired; 40 (15.4%) had both; culture date was unavailable in 27 (10.4%). The most common bacterial organisms isolated were coagulase negative staphylococci, Staphylococcus aureus, Pseudomonas sp. and Streptococcus pneumoniae. Antibiotics were prescribed in 661 (97.1%) with 3.8 (1.9) prescriptions per patient. Patients with any positive culture had longer days of MV [mean(SD); 15.2 (10.7) vs. 10.7 (9.0), p< 0.0001], ICU stay [median(IQR);18.2 (12.5) vs. 10.8 (9.0) days, p< 0.0001], hospitalization [median(IQR); 30.7 (20.7) vs. 19.2 (17.4) days, p< 0.0001] and a trend towards increased hospital mortality (25.1% vs. 19.9%, p = 0.15). Patients with ICU-acquired positive cultures had worse outcomes compared to those with positive prevalent cultures or who were culture negative. CONCLUSION: Culture-based evidence of secondary infections commonly complicates Influenza A(H1N1)-related critical illness and is associated with worse clinical outcomes despite nearly ubiquitous antibiotic administration.
[Show abstract][Hide abstract] ABSTRACT: PURPOSE: Duration of weaning from mechanical ventilation is decreased with the use of written protocols in adults. In children, the use of written protocols has not had such an impact. METHODS AND MEASUREMENTS: We conducted a single-center trial to assess the feasibility of conducting a multicenter randomized clinical trial comparing the duration of weaning from mechanical ventilation in those managed by a computer-driven explicit protocol versus usual care. Mechanically ventilated children aged between 2 and 17 years on pressure support and not receiving inotropes were included. After randomization, children were weaned either by usual care (n = 15) that was characterized by no protocolized decisions by attending physicians, or by a computer-driven protocol (Smartcare/PS™, Drager Medical) (n = 15). Weaning duration until first extubation was the primary outcome. For comparison, a Mann-Whitney U test was employed (p < 0.05). RESULTS: Patients characteristics at inclusion were similar. The median duration of weaning was 21 h (range 3-142 h) in the SmartCare/PS™ group and 90 h (range 4-552 h) in the usual care group, p = 0.007. The rate of reintubation within 48 h after extubation and the rate of noninvasive ventilation after extubation in the SmartCare/PS™ and usual care groups were 2/15 versus 1/15 and 2/15 versus 2/15, respectively. CONCLUSIONS: A pediatric randomized trial on mechanical ventilation with a computerized protocol in North America is feasible. A computer-driven protocol that also manages children younger than 2 years old would help to decrease the number of PICU admissions screened in a multicentre trial on this topic.
European Journal of Intensive Care Medicine 01/2013; · 5.17 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mechanical ventilation is a very effective therapy, but with many complications. Simulators are used in many fields, including medicine, to enhance safety issues. In the intensive care unit, they are used for teaching cardiorespiratory physiology and ventilation, for testing ventilator performance, for forecasting the effect of ventilatory support, and to determine optimal ventilatory management. They are also used in research and development of clinical decision support systems (CDSSs) and explicit computerized protocols in closed loop. For all those reasons, cardiorespiratory simulators are one of the tools that help to decrease mechanical ventilation duration and complications. This paper describes the different types of simulators described in the literature for physiologic simulation and modeling of the respiratory system, including a new simulator (SimulResp), and proposes a validation process for these simulators.
Critical care research and practice 01/2013; 2013:943281.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE:: To prospectively evaluate relationships among serum cytokine levels, innate immune responsiveness, and mortality in a multicenter cohort of critically ill children with influenza infection. DESIGN:: Prospective, multicenter, observational study. SETTING:: Fifteen pediatric ICUs among members of the Pediatric Acute Lung Injury and Sepsis Investigators network. PATIENTS:: Patients ≤18 yrs old admitted to a PICU with community-acquired influenza infection. A control group of outpatient children was also evaluated. INTERVENTIONS:: ICU patients underwent sampling within 72 hrs of ICU admission for measurement of a panel of 31 serum cytokine levels and quantification of whole blood ex vivo lipopolysaccharide-stimulated tumor necrosis factor-α production capacity using a standardized stimulation protocol. Outpatient control subjects also underwent measurement of tumor necrosis factor-α production capacity. MEASUREMENTS AND MAIN RESULTS:: Fifty-two patients (44 survivors, eight deaths) were sampled. High levels of serum cytokines (granulocyte macrophage colony-stimulating factor, interleukin-6, interleukin-8, interferon-inducible protein-10, monocyte chemotactic protein-1, and macrophage inflammatory protein-1α) were associated with mortality (p < 0.0016 for each comparison) as was the presence of secondary infection with Staphylococcus aureus (p = 0.007), particularly methicillin-resistant S. aureus (p < 0.0001). Nonsurvivors were immunosuppressed with leukopenia and markedly reduced tumor necrosis factor-α production capacity compared with outpatient control subjects (n = 21, p < 0.0001) and to ICU survivors (p < 0.0001). This association remained after controlling for multiple covariables. A tumor necrosis factor-α response <250 pg/mL was highly predictive of death and longer duration of ICU stay (p < 0.0001). Patients with S. aureus coinfection demonstrated the greatest degree of immunosuppression (p < 0.0001). CONCLUSIONS:: High serum levels of cytokines can coexist with marked innate immune suppression in children with critical influenza. Severe, early innate immune suppression is highly associated with both S. aureus coinfection and mortality in this population. Multicenter innate immune function testing is feasible and can identify these high-risk children.
Critical care medicine 12/2012; · 6.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: INTRODUCTION: The present study is a pilot prospective safety evaluation of a new closed loop computerised protocol on ventilation and oxygenation in stable, spontaneously breathing children weighing more than 7 kg, during the weaning phase of mechanical ventilation. METHODS: Mechanically ventilated children ready to start the weaning process were ventilated for five periods of 60 minutes in the following order: pressure support ventilation, adaptive support ventilation (ASV), ASV plus a ventilation controller (ASV-CO2), ASV-CO2 plus an oxygenation controller (ASV-CO2-O2) and pressure support ventilation again. Based on breath-by-breath analysis, the percentage of time with normal ventilation as defined by a respiratory rate between 10 and 40 breaths/minute, tidal volume > 5 ml/kg predicted body weight and end-tidal CO2 between 25 and 55 mmHg was determined. The number of manipulations and changes on the ventilator were also recorded. RESULTS: Fifteen children, median aged 45 months, were investigated. No adverse event and no premature protocol termination were reported. ASV-CO2 and ASV-CO2-O2 kept the patients within normal ventilation for, respectively, 94% (91 to 96%) and 94% (87 to 96%) of the time. The tidal volume, respiratory rate, peak inspiratory airway pressure and minute ventilation were equivalent for all modalities, although there were more automatic setting changes in ASV-CO2 and ASV-CO2-O2. Positive end-expiratory pressure modifications by ASV-CO2-O2 require further investigation. CONCLUSION: Over the short study period and in this specific population, ASV-CO2 and ASV-CO2-O2 were safe and kept the patient under normal ventilation most of the time. Further research is needed, especially for positive end-expiratory pressure modifications by ASV-CO2-O2. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01095406.
Critical care (London, England) 05/2012; 16(3):R85. · 4.72 Impact Factor