[Acute respiratory distress syndrome. Etiology, physiopathology, diagnosis].
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Adult↗
Biomedical subjects
D Dreyfuss
Publications and source records attributed to D Dreyfuss.
Prevalence, etiologies and outcome of the acute respiratory distress syndrome among hypoxemic ventilated patients. SRLF Collaborative Group on Mechanical Ventilation. Société de Réanimation de Langue Française.
OBJECTIVE: To evaluate the prevalence and outcome of the acute respiratory distress syndrome (ARDS) among patients requiring mechanical ventilation. DESIGN: A prospective, multi-institutional, initial cohort study including 28-day follow-up. SETTINGS: Thirty-six French intensive care units (ICUs) from a working group of the French Intensive Care Society (SRLF). PATIENTS: All the patients entering the ICUs during a 14-day period were screened prospectively. Hypoxemic patients, defined as having a PaO(2)/FIO(2) ratio (P/F) of 300 mmHg or less and receiving mechanical ventilation, were classified into three groups, according to the Consensus Conference on ARDS: group 1 refers to ARDS (P/F: 200 mmHg or less and bilateral infiltrates on the chest X-ray); group 2 to acute lung injury (ALI) without having criteria for ARDS (200 < P/F </= 300 mmHg and bilateral infiltrates) and group 3 to patients with P/F of 300 mmHg or less but having exclusion criteria from the previous groups. RESULTS: Nine hundred seventy-six patients entered the ICUs during the study period, 43 % of them being mechanically ventilated and 213 (22 %) meeting the criteria for one of the three groups. Among all the ICU admissions, ARDS, ALI and group 3 patients amounted, respectively, to 6.9 % (67), 1.8 % (17) and 13.3 % (129) of the patients, and represented 31.5 %, 8.1 % and 60.2 % of the hypoxemic, ventilated patients. The overall mortality rate was 41 % and was significantly higher in ARDS patients than in the others (60 % vs 31 % p < 0.01). In group 3, 42 patients had P/F less than 200 mmHg associated with unilateral lung injury; mortality was significantly lower (40.5 %) than in the ARDS group. In the whole group of hypoxemic, ventilated patients, septic shock and severity indices but not oxygenation indices were significantly associated with mortality, while the association with immunosuppression revealed only a trend (p = 0.06). CONCLUSIONS: In this survey we found that very few patients fulfilled the ALI non-ARDS criteria and that the mortality of the group with ARDS was high.
Adult↗
Hyperinflation-induced lung injury during alveolar flooding in rats: effect of perfluorocarbon instillation.
Mechanical nonuniformity of diseased lungs may predispose them to ventilator-induced lung injury (VILI) by overinflation of the more compliant, aerated zones. Perfluorocarbon (PFC) may reduce this nonuniformity by suppressing air-liquid interfaces. Saline (6.8 ml/kg) was instilled into the trachea to mimic alveolar edema and reduce aerated lung volume before mechanical ventilation (6, 16, 24, or 32 ml/kg tidal volume [VT]) for 10 min in rats. Flooding significantly aggravated VILI when VT was 24 or 32 ml/kg, with an increase in the distribution space of albumin in lungs (p < 0.001). Tracheal instillation of a low dose (3.3 ml/kg) of PFC (Liquivent) either before or after the instillation of saline considerably reduced VILI (p < 0.001). Saline instillation raised the lower inflection point of the respiratory system pressure-volume curve to values as high as 25 cm H2O, and produced a significant increase in end-inspiratory pressure (from 38 +/- 2.0 cm H2O to 61 +/- 2.4 cm H2O, for a VT of 32 ml/kg; p < 0.001). PFC significantly reduced the pressure at the lower inflection point and normalized end-inspiratory pressure. These decreases were correlated with a smaller albumin distribution space (p < 0.001). Animals in which PFC instillation failed to reduce the albumin space had pressures similar to those of animals given saline alone. In conclusion, the effectiveness of PFC instillation in reducing VILI may be predicted by the shape of the pressure-volume curve. These findings may help in designing safer clinical studies of mechanical ventilation and in reducing the cost of partial liquid ventilation by reducing doses of PFC.
Animals↗
Bedside evaluation of efficient airway humidification during mechanical ventilation of the critically ill.
STUDY OBJECTIVE: To determine the correlation between simple rating of condensation seen in the flex-tube connecting the heating and humidifying device used with the endotracheal tube and hygrometric parameters (absolute and relative humidity and tracheal temperature) measured by psychrometry. DESIGN: Prospective randomized clinical trial. SETTING: Medical ICU of Louis Mourier Hospital, Colombes, France, a university-affiliated teaching hospital. PATIENTS: Forty-five consecutive mechanically ventilated critically ill patients. INTERVENTIONS: Patients undergoing mechanical ventilation were randomly assigned to receive humidification with one of the four heat and moisture exchangers (HMEs) tested or with a conventional heated humidifier. MEASUREMENTS: The hygrometric performances of four HMEs (BB2215, BB50, and BB100 from Pall Biomedical, Saint-Germaine-en-Laye, France; and Hygrobac-Dar from Mallinckrodt, Mirandola, Italy) and a heated humidifier (Fisher & Paykel; Auckland, New Zealand) were studied after 3 h and also after 48 h of use for the Hygrobac-Dar and correlated to a clinical visual inspection rating the amount of condensation in the flex-tube of the endotracheal tube. RESULTS: A total of 95 measurements in 45 patients were performed. The best hygrometric parameters were obtained with the heated humidifier (p < 0.001). The Hygrobac-Dar yielded significantly higher values for both humidities and tracheal temperature than the other three HMEs (p < 0.001). The performance of Hygrobac-Dar was unchanged after 48 h of use. There was a significant correlation between the condensation seen in the flex-tube and the hygrometric parameters measured by psychrometry (absolute humidity, rho = 0.7; relative humidity, rho = 0.7; tracheal temperature, rho = 0.5, p < 0.0001). CONCLUSION: In mechanically ventilated ICU patients, visual evaluation of the condensation in the flex-tube provides an estimation of the heating and humidifying efficacy of the heating and humidifying device used, thus allowing the clinician bedside monitoring of airway humidification.
Acute Disease↗
From ventilator-induced lung injury to multiple organ dysfunction?
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Humans↗
The American-European Consensus Conference on ARDS, part 2. Ventilatory, pharmacologic, supportive therapy, study design strategies and issues related to recovery and remodeling.
The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last ten years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathological features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.
Americas↗
Ventilator-induced lung injury: lessons from experimental studies.
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Capillary Permeability↗
The "hands-off" catheter and the prevention of systemic infections associated with pulmonary artery catheter: a prospective study.
The Arrow "Hands-Off" thermodilution catheter (AHO) is completely shielded during balloon testing, preparation, and insertion. To assess the value of the AHO in the prevention of systemic infections associated with pulmonary artery catheterization (SIAPAC), we conducted a randomized prospective study over an 18-mo period. The patients were randomly assigned to two groups, of which one received the thermodilution catheter routinely used in our department and the other, the AHO catheter. The diagnosis of SIAPAC was based on recovery of the same organism from the thermodilution catheter (TC) and blood samples, absence of any other infectious focus, and improvement or resolution of clinical evidence of infection after removal of the TC. A total of 166 TCs were randomized in 150 patients. The two groups (mean +/- SD) were comparable in terms of age, SAPS on admission (15.6 +/- 5.2 versus 15.2 +/- 6.2), SAPS on the day of catheter insertion (17.6 +/- 4.8 versus 17.3 +/- 5.8), duration of catheter insertion (22.8 +/- 11.3 versus 25.3 +/- 19.5 min), insertion site, hemodynamic status, duration of use of the TC (3.6 +/- 1.3 versus 3.5 +/- 1.5 d), and outcome. A total of eight cases of SIAPAC were diagnosed in the standard TC group, versus none in the AHO group (p < 0.002). No cases of SIAPAC occurred in those patients who had their TC for less than four days. This study demonstrates the value of the AHO for preventing systemic infections associated with prolonged pulmonary artery catheterization.
Aged↗
The American-European Consensus Conference on ARDS, part 2: Ventilatory, pharmacologic, supportive therapy, study design strategies, and issues related to recovery and remodeling. Acute respiratory distress syndrome.
The acute respiratory distress syndrome (ARDS) continues as a contributor to the morbidity and mortality of patients in intensive care units throughout the world, imparting tremendous human and financial costs. During the last 10 years there has been a decline in ARDS mortality without a clear explanation. The American-European Consensus Committee on ARDS was formed to re-evaluate the standards for the ICU care of patients with acute lung injury (ALI), with regard to ventilatory strategies, the more promising pharmacologic agents, and the definition and quantification of pathologic features of ALI that require resolution. It was felt that the definition of strategies for the clinical design and coordination of studies between centers and continents was becoming increasingly important to facilitate the study of various new therapies for ARDS.
Europe↗
Tidal volume reduction for prevention of ventilator-induced lung injury in acute respiratory distress syndrome. The Multicenter Trail Group on Tidal Volume reduction in ARDS.
Because animal studies have demonstrated that mechanical ventilation at high volume and pressure can be deleterious to the lungs, limitation of airway pressure, allowing hypercapnia if necessary, is already used for ventilation of acute respiratory distress syndrome (ARDS). Whether a systematic and more drastic reduction is necessary is debatable. A multicenter randomized study was undertaken to compare a strategy aimed at limiting the end-inspiratory plateau pressure to 25 cm H2O, using tidal volume (VT) below 10 ml/kg of body weight, versus a more conventional ventilatory approach (with regard to current practice) using VT at 10 ml/kg or above and close to normal PaCO2. Both arms used a similar level of positive end-expiratory pressure. A total of 116 patients with ARDS and no organ failure other than the lung were enrolled over 32 mo in 25 centers. The two groups were similar at inclusion. Patients in the two arms were ventilated with different VT (7.1 +/- 1.3 versus 10.3 +/- 1.7 ml/kg at Day 1, p < 0.001) and plateau pressures (25.7 +/- 5. 0 versus 31.7 +/- 6.6 cm H2O at Day 1, p < 0.001), resulting in different PaCO2 (59.5 +/- 15.0 versus 41.3 +/- 7.6 mm Hg, p < 0.001) and pH (7.28 +/- 0.09 versus 7.4 +/- 0.09, p < 0.001), but a similar level of oxygenation. The new approach did not reduce mortality at Day 60 (46.6% versus 37.9% in control subjects, p = 0.38), the duration of mechanical ventilation (23.1 +/- 20.2 versus 21.4 +/- 16. 3 d, p = 0.85), the incidence of pneumothorax (14% versus 12%, p = 0. 78), or the secondary occurrence of multiple organ failure (41% versus 41%, p = 1). We conclude that no benefit could be observed with reduced VT titrated to reach plateau pressures around 25 cm H2O compared with a more conventional approach in which normocapnia was achieved with plateau pressures already below 35 cm H2O.
Adolescent↗
Use of a pulse oximeter in an adult emergency department: impact on the number of arterial blood gas analyses ordered.
STUDY OBJECTIVES: To assess the impact of pulse oximetry (SpO2) on the indications and the number of arterial blood gas (ABG) levels ordered in an adult emergency department (ED). DESIGN: A prospective study during a 2-month period in 1993 with a pulse oximeter available and a comparison with the same period in 1992 without the oximeter. SETTING: An adult medical ED of a university hospital in France. PATIENTS: All patients who underwent ABG or SpO2 measurements. INTERVENTIONS: During the prospective study, residents ordered ABG or SpO2 measurements at their discretion. The reasons for their ordering were reviewed by two independent experts who determined whether their choice was justified. The data were compared with those for 184 consecutive patients who had ABG measurements in 1992. MEASUREMENTS AND RESULTS: The study included 152 patients. SpO2 alone was used in 33 patients; ABG levels were measured in 119 patients. The use of SpO2 did not result in the ordering of fewer useful ABG determinations. One hundred and five (88%) ABG measurements were justified. There were fewer unjustified ABG determinations in 1993 when the pulse oximeter was available than in 1992 when it was not (14 of 119 vs 54 of 184; p<0.001) mainly because fewer ABG determinations were ordered for miscellaneous nonrespiratory indications (13 of 119 vs 43 of 184; p<0.01). CONCLUSION: The availability of a pulse oximeter did not affect the ordering of useful ABG measurements but allowed a significant reduction of unjustified ABG measurements. Substantial cost savings could be achieved by using SpO2 in an ED.
Adult↗
Role of distal airspace epithelium for resolving alveolar edema.
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Absorption↗
[Experimental changes in the alveolo-capillary barrier induced by artificial ventilation].
Mechanical ventilation can have deleterious effects on the lungs. Extra-alveolar escape of air, such as pneumothorax or subcutaneous emphysema, are complications which have long been known. New experimental studies have clearly shown that mechanical ventilation can also result in pathologic changes to the air/blood barrier. Mechanical ventilation with high end-inspiratory pressure and high volume causes lung edema in whose origin abnormal permeability of the alveolo-capillary barrier plays a major role. The abnormalities are in fact the result of pulmonary distention and not of elevated air pressure; this justifies the term "volume traumatism". The presence of a previous acute pulmonary injury considerably increases the deleterious effects of mechanical ventilation on the lungs. Although the clinical implications of these experimental studies are difficult to assess, they have nevertheless resulted in major changes in ventilation strategy for acute lung diseases such as the acute respiratory distress syndrome of the adult.
Adult↗
Measurement of cardiac output by transesophageal echocardiography in mechanically ventilated patients. Comparison with thermodilution.
OBJECTIVE: The determination of basal cardiac output (CO) and of its variations during different therapeutic interventions liable to increase or decrease it in mechanically ventilated patients using transesophageal echocardiography (TEE). DESIGN: To compare CO measurements simultaneously obtained by transmitral single-plane TEE and thermodilution. SETTING: Medical intensive care unit. PATIENTS: Twenty-two consecutive mechanically ventilated patients hospitalized for various medical conditions were included. INTERVENTIONS: The comparisons between transmitral single-plane TEE and thermodilution measurements were made at baseline and after different therapeutic interventions affecting CO (fluids or dobutamine infusion or positive end-expiratory pressure titration). MEASUREMENTS: Seventy-four measurements were obtained. Cardiac output using TEE was the product of the mitral valve area, the time-velocity integral of flow at the same site and the heart rate. RESULTS: A significant correlation was observed between thermodilution and TEE measurements of CO (n = 74, r = 0.78, p < 0.001) despite wide limits of agreement (mean +/- 2SD = -0.3 +/- 3.1 l/min). Thermodilution and TEE CO determinations both had significant inverse correlation with the arterial-venous oxygen content difference in ten consecutive patients (r = 0.77, p < 0.01 and r = 0.71, p < 0.01, respectively). The correlation between variations of CO greater than 20% obtained by thermodilution and TEE was significant (r = 0.89, p < 0.001). The operative characteristics implied the ability of TEE to predict significant variations of thermodilution CO (sensitivity 85% and negative predictive values 86%). Moreover, arterial-venous oxygen content difference changes of 5% or more were better detected using TEE than thermodilution. CONCLUSIONS: These results suggest that although transesophageal CO measurements cannot replace thermodilution ones, the determination of CO variations obtained using TEE may be useful in the management of critically ill mechanically ventilated patients. This technique may make it possible to monitor hemodynamics during initial therapeutic interventions in those patients in whom right heart catheterization cannot be performed immediately.
Adult↗
Pressure-heart rate responses to alpha-adrenergic stimulation and hormonal regulation in normotensive patients with obstructive sleep apnea.
Seven normotensive untreated patients with obstructive sleep apnea (OSA) and five control subjects without OSA were compared. Patients with cardiac dilation, chronic airflow limitation, liver and kidney disease, or diabetes mellitus were excluded. Change in pressure-heart rate relation to alpha-adrenergic stimulation (P-HRR), extracellular volume (ECV), and plasma volume (Vp) were measured during daytime. Plasma atrial natriuretic peptide (ANP), plasma renin and aldosterone concentrations were obtained at 1 hour intervals during the night. A mean apnea/hypopnea index (AHI) of 52.2 +/- 23.9/h and a mean lowest arterial oxygen saturation (SaO2) of 61.2 +/- 19.3% (mean +/- SD) were determined from polysomnographic monitoring in the patient group. Release of ANP was significantly higher during sleep in OSA patients than in control subjects (P < .01), with a maximum concentration between 4 and 6 AM in the former. Daytime ECV was significantly higher (P < .05) and Vp significantly lower (P < .05) in OSA patients. Night maximum concentration of ANP (max ANP) was negatively related to AHI (P < .05). P-HRR was negatively related to AHI (P < .05) and positively related to max ANP (P < .05). In conclusion, OSA syndrome alters hormonal system control of body fluid compartment regulation. The decreased response in night max ANP secretion in the most severe OSA patients could be explained by the smaller Vp observed in these patients, decreasing atrial and ventricular pressure loading. Furthermore, alteration of P-HRR, correlated to AHI and max ANP, strengthens the hypothesis that patients who develop hypertension are those in whom the protective mechanism of ANP release failed.
Adrenergic alpha-Agonists↗
Elastic energy as an index of right ventricular filling.
BACKGROUND: Right ventricle (RV) preload assessment remains controversial because the complexity of RV geometry is an obstacle to wall stress modeling. We developed a method to evaluate end-diastolic RV elastic energy (EL), a variable that integrates all the stretching effects of venous return and that can be easily estimated at the bedside from the area under the diastolic RV pressure-volume curve. The purpose of this study was to compare the clinical utility of EL and of the two conventional variables used to assess RV filling, ie, right atrial pressure (Pra) and RV end-diastolic volume (EDV). METHOD: We studied 26 postoperative patients who required a rapid fluid challenge. Energetics were evaluated by constructing the RV pressure-volume loop at the bedside using right heart catheterization with RV ejection fraction (EF) derivation. Correlations between RV filling and RV performance (ejection and mechanical efficiency) were studied. RV filling indexes were Pra, EDV, and EL. Indexes of RV ejection were stroke volume (SV), RV stroke work (RVSW), mechanical energy expenditure during ejection (EM), and total energy expenditure of contraction (ET). Indexes of RV mechanical efficiency were EF and the EM/ET ratio. RESULTS: Three important results were obtained. First, among RV ejection indexes, those that correlated best with RV filling indexes were EM and ET. Second, we found significant linear relationships between improved RV filling, as assessed by changes in EDV and EL, and improved RV ejection, as assessed by changes in SV, RVSW, EM, or ET. Third, changes in EDV and EL also predicted improved mechanical efficiency, as assessed by changes in EF and EM/ET. In, all situations, changes in EL yielded the strongest correlations. CONCLUSIONS: Derivation of EL is simple and appears to be the best clinical means of assessing Starling's law of the heart for the RV.
Adult↗
Correlation between simple clinical parameters and the in vitro humidification characteristics of filter heat and moisture exchangers. Groupe de Travail sur les Respirateurs.
STUDY OBJECTIVE: This study on ventilated patients in ICUs examined a large sample of heat and moisture exchanger filters (HMEFs) to determine whether simple clinical parameters are correlated with exchanger humidity output. DESIGN: A total of 594 HMEFs (18 types of HMEF) were tested in nine university hospital ICUs. PATIENTS: Each HMEF was tested on one different unselected and consecutive patient for 24 h. INTERVENTIONS: The following parameters were rated at each tracheal aspiration on a scale of 0 to 3: secretion abundance, viscosity (Visc), suction catheter adherence (Adh) to the endotracheal tube, and the amount of water condensed in the flex tube (Cond). Individual values for each type of HMEF and each variable were averaged and correlated with the humidity output (HO) of the HMEFs, values which were supplied by the manufacturers. RESULTS: There were significant correlations between HO and Cond (r=0.82, p<10(-3)), Visc (r=-0.67, p=0.002), and Adh (r=-0.56, p=0.01). A second study recorded the same variables, for three consecutive 24-h periods, using first a high-humidifying HMEF (DAR Hygrobac), followed by a low-humidifying one (Pall BB22-15), and again DAR Hygrobac. Visc and Adh were higher (p<0.05) and Cond was lower (p<0.05) with the Pall than with the DAR. CONCLUSIONS: Simple clinical parameters correlate well with the efficiency of HMEFs. The apparent water condensed in the flex tubing seems to be the best indicator of the humidifying efficiency of HMEFs.
Adhesiveness↗
Ventilator circuit changes.
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Cross Infection↗