François Lellouche

Impact of deep sternal wound infection management with vacuum-assisted closure therapy followed by sternal osteosynthesis: a 15-year review of 23 499 sternotomies

OBJECTIVEnThis study was undertaken to examine the outcome of patients with deep sternal wound infection (DSWI) now treated with vacuum-assisted closure (VAC) therapy as a bridge to sternal osteosynthesis with horizontal titanium plate fixation.nnnMETHODSnFrom 1992 to 2007, a consecutive cohort of 23,499 patients underwent open-heart surgery (OHS) in our institution. The period under study was divided in two according to the use of therapeutic modalities: conventional (1992-2001, N=118 DSWI): debridement/drainage with primary closure and irrigation (N=37), debridement/drainage, open packing followed by pectoralis myocutaneous flaps (PMFs) (N=81); contemporary (2002-2007, N=149 DSWI): conventional treatment (N=24) and VAC therapy (N=125/83.8%). VAC was followed by sternal osteosynthesis with horizontal titanium plates in 92 patients (61.7%).nnnRESULTSnDSWI was diagnosed in 267 out of 23 499 (1.1%) patients of our entire series according to Center for Disease Control - Atlanta (CDC) criteria, 118 out of 13 180 (0.9%) in the first and 149 out of 10 319 (1.4%) in the second period (p=0.001). Hospital mortality (N=267/23,499) has been 10.25% for the entire cohort under study without any difference between groups (1992-2001: 11.4%; 2002-2007: 9.1%, p=0.67). More recently, VAC therapy (N=125) was associated with a lower mortality (4.8% vs 14.1%, p=0.01). Stepwise multivariable logistic regression analysis for both periods revealed that prolonged intubation in the intensive care unit (ICU), use of bilateral internal thoracic artery grafting (BIMA), diabetes, re-operation for bleeding and body mass index (BMI) >30 kgm(-2) are the most powerful predictors of DSWI. In the more recently treated patients using VAC therapy, combined procedures (valve and graft) also emerged as a significant predictor. For the entire study, Staphylococcus epidermidis (49.6%) has been the most frequently identified pathogen, followed by Staphylococcus aureus (38.8%). Methicillin-resistant S.aureus (MRSA) was observed in 4.9% of the cohort. Neither of these bacteria was associated with increased mortality. Survival analysis with Cox regression model and propensity score adjustment in patients with DSWI showed freedom from all-cause mortality at 1, 5 and 10 years to be, respectively, 91.8%, 80.4% and 61.3% compared with 94.0%, 85.5% and 70.2%, respectively, for patients submitted to OHS without DSWI (p=0.01). Early adjusted survival for patients with DSWI treated with VAC therapy was 92.8%, 89.8% and 88.0%, respectively, at 1, 2 and 3 years, compared with 83.0%, 76.4% and 61.3%, respectively, for patients with DSWI treated without VAC (p=0.02).nnnCONCLUSIONSnDSWI remains a major and challenging complication of OHS. VAC therapy with sternal preservation followed by delayed sternal osteosynthesis and PMF has been recently proposed as a new therapeutic strategy. Most patients treated with VAC therapy in our second group showed decreased perioperative mortality and increased short-term survival.

Automating the weaning process with advanced closed-loop systems

BackgroundLimiting the duration of invasive ventilation is an important goal in caring for critically ill patients. Several clinical trials have shown that compared to traditional care, protocols can reduce the total duration of mechanical ventilation. Computerized or automated weaning has the potential to improve weaning, while decreasing associated workload, and to transfer best evidence into clinical practice by integrating closed-loop technology into protocols that can be operationalized continuously.DiscussionIn this article, we review the principles of automated systems, discuss automated systems that can be used during weaning, and examine the best-current evidence from randomized trials and observational studies supporting their use. We highlight three commercially available systems (Mandatory Minute Ventilation, Adaptive Support Ventilation and SmartCare™) that can be used to automate the weaning process. We note advantages and disadvantages associated with individual weaning systems and differences among them.ConclusionsWe discuss the potential role for automation in complimenting clinical acumen, reducing practice pattern variation and facilitating knowledge translation into clinical practice, and underscore the need for additional high quality investigations to evaluate automated weaning systems in different practice settings and diverse patient populations.

Restrictive or Liberal Red-Cell Transfusion for Cardiac Surgery

BACKGROUND The effect of a restrictive versus liberal red‐cell transfusion strategy on clinical outcomes in patients undergoing cardiac surgery remains unclear. METHODS In this multicenter, open‐label, noninferiority trial, we randomly assigned 5243 adults undergoing cardiac surgery who had a European System for Cardiac Operative Risk Evaluation (EuroSCORE) I of 6 or more (on a scale from 0 to 47, with higher scores indicating a higher risk of death after cardiac surgery) to a restrictive red‐cell transfusion threshold (transfuse if hemoglobin level was <7.5 g per deciliter, starting from induction of anesthesia) or a liberal red‐cell transfusion threshold (transfuse if hemoglobin level was <9.5 g per deciliter in the operating room or intensive care unit [ICU] or was <8.5 g per deciliter in the non‐ICU ward). The primary composite outcome was death from any cause, myocardial infarction, stroke, or new‐onset renal failure with dialysis by hospital discharge or by day 28, whichever came first. Secondary outcomes included red‐cell transfusion and other clinical outcomes. RESULTS The primary outcome occurred in 11.4% of the patients in the restrictive‐threshold group, as compared with 12.5% of those in the liberal‐threshold group (absolute risk difference, ‐1.11 percentage points; 95% confidence interval [CI], ‐2.93 to 0.72; odds ratio, 0.90; 95% CI, 0.76 to 1.07; P<0.001 for noninferiority). Mortality was 3.0% in the restrictive‐threshold group and 3.6% in the liberal‐threshold group (odds ratio, 0.85; 95% CI, 0.62 to 1.16). Red‐cell transfusion occurred in 52.3% of the patients in the restrictive‐threshold group, as compared with 72.6% of those in the liberal‐threshold group (odds ratio, 0.41; 95% CI, 0.37 to 0.47). There were no significant between‐group differences with regard to the other secondary outcomes. CONCLUSIONS In patients undergoing cardiac surgery who were at moderate‐to‐high risk for death, a restrictive strategy regarding red‐cell transfusion was noninferior to a liberal strategy with respect to the composite outcome of death from any cause, myocardial infarction, stroke, or new‐onset renal failure with dialysis, with less blood transfused. (Funded by the Canadian Institutes of Health Research and others; TRICS III ClinicalTrials.gov number, NCT02042898.)

Prophylactic protective ventilation: lower tidal volumes for all critically ill patients?

High tidal volumes have historically been recommended for mechanically ventilated patients during general anesthesia. High tidal volumes have been shown to increase morbidity and mortality in patients suffering from acute respiratory distress syndrome (ARDS). Barriers exist in implementing a tidal volume reduction strategy related to the inherent difficulty in changing ones practice patterns, to the current need to individualize low tidal volume settings only for a specific subgroup of mechanically ventilated patients (i.e., ARDS patients), the difficulty in determining the predicated body weight (requiring the patients height and a complex formula). Consequently, a protective ventilation strategy is often under-utilized as a therapeutic option, even in ARDS. Recent data supports the generalization of this strategy prophylactically to almost all mechanically ventilated patients beginning immediately following intubation. Using tools to rapidly and reliably determine the predicted body weight (PBW), as well as the use of automated modes of ventilation are some of the potential solutions to facilitate the practice of protective ventilation and to finally ventilate our patients’ lungs in a more gentle fashion to help prevent ARDS.

Comparison of patient-ventilator interfaces based on their computerized effective dead space.

PurposeNon-invasive ventilation is largely used to treat acute and chronic respiratory failure. This ventilation encounters a non-negligible rate of failure related to the used interface/mask, but the reasons for this failure remain unclear. In order to shed light on this issue and to better understand the effects of the geometrical design of interfaces, we aimed to quantify flow, pressure and gas composition in terms of CO2 and O2 at the passage through different types of interface (oronasal mask, integral mask and helmet). In particular, we postulated that due to specific gas flow passing throughout the interface, the effective dead space added by the interface is not always related to the whole gas volume included in the interface.MethodsNumerical simulations, using computational fluid dynamics, were used to describe pressure, flow and gas composition during ventilation with the different interfaces.ResultsBetween the different interfaces the effective dead spaces differed only modestly (110–370xa0ml), whereas their internal volumes were markedly different (110–10,000xa0ml). Effective dead space was limited to half the tidal volume for the most voluminous interface, whereas it was close to the interface gas volume for the less voluminous interfaces. Pressure variations induced by the flow ventilation throughout the interface were negligible.ConclusionsEffective dead space is not related to the internal gas volume included in the interface, suggesting that this internal volume should not be considered as a limiting factor for their efficacy during non-invasive ventilation. Patient’s comfort and synchrony have also to be taken into account.

Evaluation of fully automated ventilation: a randomized controlled study in post-cardiac surgery patients

PurposeDiscrepancies between the demand and availability of clinicians to care for mechanically ventilated patients can be anticipated due to an aging population and to increasing severity of illness. The use of closed-loop ventilation provides a potential solution. The aim of the study was to evaluate the safety of a fully automated ventilator.MethodsWe conducted a randomized controlled trial comparing automated ventilation (AV) and protocolized ventilation (PV) in 60 ICU patients after cardiac surgery. In the PV group, tidal volume, respiratory rate, FiO2 and positive end-expiratory pressure (PEEP) were set according to the local hospital protocol based on currently available guidelines. In the AV group, only sex, patient height and a maximum PEEP level of 10 cmH2O were set. The primary endpoint was the duration of ventilation within a “not acceptable” range of tidal volume. Zones of optimal, acceptable and not acceptable ventilation were based on several respiratory parameters and defined a priori.ResultsThe patients were assigned equally to each group, 30 to PV and 30 to AV. The percentage of time within the predefined zones of optimal, acceptable and not acceptable ventilation were 12xa0%, 81xa0%, and 7xa0% respectively with PV, and 89.5xa0%, 10xa0% and 0.5xa0% with AV (Pxa0<xa00.001). There were 148 interventions required during PV compared to only 5 interventions with AV (Pxa0<xa00.001).ConclusionFully AV was safe in hemodynamically stable patients immediately following cardiac surgery. In addition to a reduction in the number of interventions, the AV system maintained patients within a predefined target range of optimal ventilation.

Decreasing the adverse effects of endotracheal suctioning during mechanical ventilation by changing practice

BACKGROUND: Little is known about the incidence of and risk factors for adverse effects from endotracheal suctioning. We studied the incidence and risk factors, and evaluated the effect of suctioning practice guidelines. METHODS: During a 3-month period, in 79 mechanically ventilated subjects, we recorded the adverse effects in 4,506 suctioning procedures. Then practice guidelines were implemented, and 1 year later, during another 3-month period, in 68 subjects, we recorded the adverse effects in 4,994 suctioning procedures. RESULTS: In the first period, adverse effects occurred frequently: oxygen desaturation in 46.8% of subjects and 6.5% of suctionings, hemorrhagic secretions in 31.6% of subjects and 4% of suctionings, blood pressure change in 24.1% of subjects and 1.6% of suctionings, and heart rate change in 10.1% of subjects and 1.1% of suctionings. After guidelines implementation, all complications, both separately and all together, were reduced. The incidence of all complications together decreased from 59.5% to 42.6% of subjects, and from 12.4% to 4.9% of procedures (both P < .05). PEEP > 5 cm H2O was an independent risk factor for oxygen desaturation. Receiving > 6 suctionings per day was a risk factor for desaturation and hemorrhagic secretions. The use of guidelines was independently associated with fewer complications. CONCLUSIONS: Endotracheal suctioning frequently induces adverse effects. Technique, suctioning frequency, and higher PEEP are risk factors for complications. Their incidence can be reduced by the implementation of suctioning guidelines.

Weaning critically ill adults from invasive mechanical ventilation: a national survey

PurposeTo determine the stated practices of clinicians in weaning critically ill adults from invasive ventilation.MethodsWe conducted a cross-sectional, self-administered postal survey of Critical Care physicians and respiratory therapists (RTs) in leadership roles at Canadian teaching hospitals. We identified respondents using electronic mail and telephone correspondence. We used rigorous survey methodology to develop, test, and administer the questionnaire.ResultsOne hundred ten of 162 (67.9%) clinicians returned the survey with 99 respondents (55 physicians and 44 RTs) completing it either in-part or in-full. Approximately 95% of respondents acknowledged ever performing spontaneous breathing trials (SBTs) in clinical practice. Of these, 95.6% and 32% of respondents reported conducting daily and twice-daily screening to identify SBT candidates, at least sometimes. The three most common techniques to conduct SBTs included; pressure support (PS) with positive end-expiratory pressure (70.8%), continuous positive airway pressure (35.7%), and use of a T-piece (25.0%). PS ventilation was the weaning strategy used most frequently before SBTs. Most respondents (57.1%) considered continuous infusion of sedative-hypnotics to be a relative contraindication to tracheal extubation. However, concurrent administration of low dose vasopressors, inotropes, and analgesic boluses, or continuous analgesic infusions were considered acceptable amongst 60.8%, 73.2%, 78.4% and 58.8% of respondents, respectively. We did not observe regional variation in whether clinicians ever perform SBTs, the ventilatory modes used prior to an SBT nor in the use of PS and SBTs during the weaning process.ConclusionsPressure support and SBTs are common features of weaning in Canadian teaching hospitals. Compared to the published literature, our survey suggests that weaning practices have evolved over time and that practice variation may be greater on an international level compared to a national level.RésuméObjectifDéterminer les pratiques déclarées des cliniciens concernant le sevrage des patients adultes gravement malades de la ventilation invasive.MéthodeNous avons réalisé un sondage transversal, auto-administré et envoyé par courrier auprès des médecins des soins critiques et des inhalothérapeutes occupant des positions de leadership dans les hôpitaux d’enseignement canadiens. Nous avons identifié les répondants à l’aide de correspondance par courrier électronique et par téléphone. Nous avons utilisé une méthodologie de sondage rigoureuse afin d’élaborer, de tester et d’administrer le questionnaire.RésultatsSur un total de 162 cliniciens, 110 (67,9%) ont renvoyé le questionnaire; 99 répondants (55xa0médecins et 44 inhalothérapeutes) ont complété le questionnaire en entier ou en partie. Environ 95xa0% des répondants ont reconnu qu’ils réalisaient des tests de ventilation spontanée (TVS) dans leur pratique clinique. Parmi ceux-ci, 95,6xa0% et 32xa0% des répondants ont affirmé réaliser des dépistages quotidiens ou deux fois par jour pour identifier les candidats potentiels à un TVS, au moins des fois. Les trois techniques les plus fréquentes pour réaliser les TVS étaientxa0: aide inspiratoire (AI) avec pression positive télé-expiratoire (70,8xa0%), ventilation en pression positive continue (35,7xa0%), et utilisation d’un tube en T (25,0xa0%). L’aide inspiratoire était la stratégie de sevrage la plus fréquemment utilisée avec les TVS. La plupart des répondants (57,1xa0%) ont estimé que la perfusion simultanée d’agents sédatifs hypnotiques constituait une contre-indication relative à l’extubation trachéale. Toutefois, l’administration simultanée de vasopresseurs, d’inotropes et de bolus d’analgésiques en dosage réduit, ou de perfusions analgésiques continues, était considérée comme acceptable par 60,8xa0%, 73,2xa0%, 78,4xa0% et 58,8xa0% des répondants, respectivement. Nous n’avons pas observé de variations régionales dans la fréquence de dépistage, les modes de ventilation utilisés avant de réaliser un TVS ou l’utilisation d’AI et de TVS pendant le processus de sevrage.ConclusionL’AI et les TVS sont des traits communs du sevrage dans les hôpitaux d’enseignement au Canada. Par rapport à la littérature publiée, notre sondage suggère que les pratiques de sevrage ont évolué avec le temps et que les variations de pratique pourraient être plus grandes entre les régions plutôt qu’au sein des régions du Canada.

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

PurposeThe 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.MethodsA 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 25xa0days. Breathing pattern, occlusion pressure (P0.1), intrinsic PEEP (PEEPi), 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.ResultsThe 45° position was associated with the lowest levels of effort (pxa0≤xa00.01) and occlusion pressure (pxa0<xa00.05), and tended to be more often comfortable. Respiratory effort was the lowest at 45° in 18/24 patients. PEEPi and PEEPi-related work were slightly higher in the supine position (pxa0≤xa00.01), whereas respiratory effort, heart rate, and P0.1 values were increased in the seated position (pxa0<xa00.05).ConclusionA 45° position helps to unload the respiratory muscles, moderately reduces PEEPi, and is often considered as comfortable. The semi-seated position may help the weaning process in ventilator-dependent patients.

Short-Term Effects of Humidification Devices on Respiratory Pattern and Arterial Blood Gases During Noninvasive Ventilation

BACKGROUND: The impact of humidification devices on ventilatory and arterial blood gases parameters during noninvasive ventilation (NIV) remains controversial. The aim of the study was to compare the short-term impact of heat and moisture exchangers (HMEs) and heated humidifiers (HHs) during NIV for either hypercapnic or hypoxemic acute respiratory failure. METHODS: Consecutive subjects receiving NIV were successively treated with HME and HH in randomized order for 30 min each. At the end of each period, arterial blood gases were measured and ventilatory parameters were recorded. RESULTS: Eighty-one subjects were enrolled, of whom 52 were hypercapnic (with or without acidosis) and 29 hypoxemic. Minute ventilation was greater with the HME, in comparison with the HH (15 [12–18] vs 12 [10–16] median [interquartile range], P < .001), while PaCO2 was increased when using HME, indicating a dead space effect. This effect was observed in all subjects, but was more pronounced in hypercapnic subjects (PaCO2 62 ± 17 mm Hg with HME vs 57 ± 14 with HH, P < .001). In a subgroup of 19 subjects with respiratory acidosis, alveolar hypoventilation improved only with the HH. The amplitude of the dead space impact was a function of the degree of hypercapnia. CONCLUSIONS: Use of an HME decreased CO2 elimination during NIV, despite increased minute ventilation, especially in hypercapnic subjects.