Management and outcome of mechanically ventilated patients after cardiac arrest.

INTRODUCTION: The aim of this study was to describe and compare the changes in ventilator management and complications over time, as well as variables associated with 28-day hospital mortality in patients receiving mechanical ventilation (MV) after cardiac arrest. METHODS: We performed a secondary analysis of three prospective, observational multicenter studies conducted in 1998, 2004 and 2010 in 927 ICUs from 40 countries. We screened 18,302 patients receiving MV for more than 12 hours during a one-month-period. We included 812 patients receiving MV after cardiac arrest. We collected data on demographics, daily ventilator settings, complications during ventilation and outcomes. Multivariate logistic regression analysis was performed to calculate odds ratios, determining which variables within 24 hours of hospital admission were associated with 28-day hospital mortality and occurrence of acute respiratory distress syndrome (ARDS) and pneumonia acquired during ICU stay at 48 hours after admission. RESULTS: Among 812 patients, 100 were included from 1998, 239 from 2004 and 473 from 2010. Ventilatory management changed over time, with decreased tidal volumes (VT) (1998: mean 8.9 (standard deviation (SD) 2) ml/kg actual body weight (ABW), 2010: 6.7 (SD 2) ml/kg ABW; 2004: 9 (SD 2.3) ml/kg predicted body weight (PBW), 2010: 7.95 (SD 1.7) ml/kg PBW) and increased positive end-expiratory pressure (PEEP) (1998: mean 3.5 (SD 3), 2010: 6.5 (SD 3); P <0.001). Patients included from 2010 had more sepsis, cardiovascular dysfunction and neurological failure, but 28-day hospital mortality was similar over time (52% in 1998, 57% in 2004 and 52% in 2010). Variables independently associated with 28-day hospital mortality were: older age, PaO2 <60 mmHg, cardiovascular dysfunction and less use of sedative agents. Higher VT, and plateau pressure with lower PEEP were associated with occurrence of ARDS and pneumonia acquired during ICU stay. CONCLUSIONS: Protective mechanical ventilation with lower VT and higher PEEP is more commonly used after cardiac arrest. The incidence of pulmonary complications decreased, while other non-respiratory organ failures increased with time. The application of protective mechanical ventilation and the prevention of single and multiple organ failure may be considered to improve outcome in patients after cardiac arrest.

Evolution of mortality over time in patients receiving mechanical ventilation.

RATIONALE: Baseline characteristics and management have changed over time in patients requiring mechanical ventilation; however, the impact of these changes on patient outcomes is unclear. OBJECTIVES: To estimate whether mortality in mechanically ventilated patients has changed over time. METHODS: Prospective cohort studies conducted in 1998, 2004, and 2010, including patients receiving mechanical ventilation for more than 12 hours in a 1-month period, from 927 units in 40 countries. To examine effects over time on mortality in intensive care units, we performed generalized estimating equation models. MEASUREMENTS AND MAIN RESULTS: We included 18,302 patients. The reasons for initiating mechanical ventilation varied significantly among cohorts. Ventilatory management changed over time (P < 0.001), with increased use of noninvasive positive-pressure ventilation (5% in 1998 to 14% in 2010), a decrease in tidal volume (mean 8.8 ml/kg actual body weight [SD = 2.1] in 1998 to 6.9 ml/kg [SD = 1.9] in 2010), and an increase in applied positive end-expiratory pressure (mean 4.2 cm H2O [SD = 3.8] in 1998 to 7.0 cm of H2O [SD = 3.0] in 2010). Crude mortality in the intensive care unit decreased in 2010 compared with 1998 (28 versus 31%; odds ratio, 0.87; 95% confidence interval, 0.80-0.94), despite a similar complication rate. Hospital mortality decreased similarly. After adjusting for baseline and management variables, this difference remained significant (odds ratio, 0.78; 95% confidence interval, 0.67-0.92). CONCLUSIONS: Patient characteristics and ventilation practices have changed over time, and outcomes of mechanically ventilated patients have improved. Clinical trials registered with www.clinicaltrials.gov (NCT01093482).

An analysis of 332 fatalities infected with pandemic 2009 influenza A (H1N1) in Argentina.

BACKGROUND: The apparent high number of deaths in Argentina during the 2009 pandemic led to concern that the influenza A H1N1pdm disease was different there. We report the characteristics and risk factors for influenza A H1N1pdm fatalities. METHODS: We identified laboratory-confirmed influenza A H1N1pdm fatalities occurring during June-July 2009. Physicians abstracted data on age, sex, time of onset of illness, medical history, clinical presentation at admission, laboratory, treatment, and outcomes using standardize questionnaires. We explored the characteristics of fatalities according to their age and risk group. RESULTS: Of 332 influenza A H1N1pdm fatalities, 226 (68%) were among persons aged <50 years. Acute respiratory failure was the leading cause of death. Of all cases, 249 (75%) had at least one comorbidity as defined by Advisory Committee on Immunization Practices. Obesity was reported in 32% with data and chronic pulmonary disease in 28%. Among the 40 deaths in children aged <5 years, chronic pulmonary disease (42%) and neonatal pathologies (35%) were the most common co-morbidities. Twenty (6%) fatalities were among pregnant or postpartum women of which only 47% had diagnosed co-morbidities. Only 13% of patients received antiviral treatment within 48 hours of symptom onset. None of children aged <5 years or the pregnant women received antivirals within 48 h of symptom onset. As the pandemic progressed, the time from symptom-onset to medical care and to antiviral treatment decreased significantly among case-patients who subsequently died (p<0.001). CONCLUSION: Persons with co-morbidities, pregnant and who received antivirals late were over-represented among influenza A H1N1pdm deaths in Argentina, though timeliness of antiviral treatment improved during the pandemic.

An assessment of the Acute Kidney Injury Network creatinine-based criteria in patients submitted to mechanical ventilation.

BACKGROUND AND OBJECTIVES: The aim of our study was to assess the new diagnostic criteria of acute kidney injury (AKI) proposed by the Acute Kidney Injury Network (AKIN) in a large cohort of mechanically ventilated patients. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: This is a prospective observational cohort study enrolling 2783 adult intensive care unit patients under mechanical ventilation (MV) with data on serum creatinine concentration (SCr) in the first 48 hours. The absolute and the relative AKIN diagnostic criteria (changes in SCr ≥ 0.3 mg/dl or ≥ 50% over the first 48 hours of MV, respectively) were analyzed separately. In addition, patients were classified into three groups according to their change in SCr (ΔSCr) over the first day on MV (ΔSCr): group 1, ΔSCr ≤ -0.3 mg/dl; group 2, ΔSCr between -0.3 and +0.29 mg/dl; and group 3, ΔSCr ≥ +0.3 mg/dl). The primary end point was in-hospital mortality, and secondary end points were intensive care unit and hospital length of stay, and duration of MV. RESULTS: Of 2783 patients, 803 (28.8%) had AKI according to both criteria: 431 only absolute (AKI(A)), 362 both relative and absolute (AKI(R+A)), and 10 only relative. The relative criterion identified more patients when baseline SCr (SCr0) was <0.9 mg/dl and the absolute when SCr0 was >1.5 mg/dl. The diagnosis of AKI was associated with mortality. CONCLUSIONS: Our study confirms the validity of the AKIN criteria in a population of mechanically patients and the criteria's relationship with the baseline SCr.

Characteristics and outcomes of ventilated patients according to time to liberation from mechanical ventilation.

RATIONALE: A new classification of patients based on the duration of liberation of mechanical ventilation has been proposed. OBJECTIVES: To analyze outcomes based on the new weaning classification in a cohort of mechanically ventilated patients. METHODS: Secondary analysis included 2,714 patients who were weaned and underwent scheduled extubation from a cohort of 4,968 adult patients mechanically ventilated for more than 12 hours. MEASUREMENTS AND MAIN RESULTS: Patients were classified according to a new weaning classification: 1,502 patients (55%) as simple weaning,1,058 patients (39%) as difficult weaning, and 154 (6%) as prolonged weaning.Variables associated with prolonged weaning(.7d)were: severity at admission (odds ratio [OR] per unit of Simplified Acute Physiology Score II, 1.01; 95% confidence interval [CI], 1.001­1.02), duration of mechanical ventilation before first attempt of weaning (OR per day, 1.10; 95% CI, 1.06­1.13), chronic pulmonary disease other than chronic obstructive pulmonary disease (OR,13.23; 95% CI, 3.44­51.05), pneumonia as the reason to start mechanical ventilation (OR, 1.82; 95% CI, 1.07­3.08), and level of positive end-expiratory pressure applied before weaning (OR per unit,1.09; 95% CI, 1.04­1.14). The prolonged weaning group had a nonsignificant trend toward a higher rate of reintubation (P » 0.08),tracheostomy (P » 0.15), and significantly longer length of stay and higher mortality in the intensive care unit (OR for death, 1.97;95%CI, 1.17­3.31). The adjusted probability of death remained constant until Day 7, at which point it increased to 12.1%.

Management and outcome of mechanically ventilated neurologic patients.

OBJECTIVE: To describe and compare characteristics, ventilatory practices, and associated outcomes among mechanically ventilated patients with different types of brain injury and between neurologic and nonneurologic patients. DESIGN: Secondary analysis of a prospective, observational, and multicenter study on mechanical ventilation. SETTING: Three hundred forty-nine intensive care units from 23 countries. PATIENTS: We included 552 mechanically ventilated neurologic patients (362 patients with stroke and 190 patients with brain trauma). For comparison we used a control group of 4,030 mixed patients who were ventilated for nonneurologic reasons. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We collected demographics, ventilatory settings, organ failures, and complications arising during ventilation and outcomes. Multivariate logistic regression analysis was performed with intensive care unit mortality as the dependent variable. At admission, a Glasgow Coma Scale score ≤8 was observed in 68% of the stroke, 77% of the brain trauma, and 29% of the nonneurologic patients. Modes of ventilation and use of a lung-protective strategy within the first week of mechanical ventilation were similar between groups. In comparison with nonneurologic patients, patients with neurologic disease developed fewer complications over the course of mechanical ventilation with the exception of a higher rate of ventilator-associated pneumonia in the brain trauma cohort. Neurologic patients showed higher rates of tracheotomy and longer duration of mechanical ventilation. Mortality in the intensive care unit was significantly (p < .001) higher in patients with stroke (45%) than in brain trauma (29%) and nonneurologic disease (30%). Factors associated with mortality were: stroke (in comparison to brain trauma), Glasgow Coma Scale score on day 1, and severity at admission in the intensive care unit. CONCLUSIONS: In our study, one of every five mechanically ventilated patients received this therapy as a result of a neurologic disease. This cohort of patients showed a higher mortality rate than nonneurologic patients despite a lower incidence of extracerebral organ dysfunction.

Outcome of reintubated patients after scheduled extubation.

PURPOSE: The main objective of study was to evaluate the outcome of patients who require reintubation after elective extubation. MATERIALS AND METHODS: This is an observational, prospective cohort study including mechanically ventilated patients who passed successfully a spontaneous breathing trial. Patients were observed for 48 hours after extubation. During this time, reintubation or use of noninvasive positive pressure ventilation was considered as a failure. Reintubated patients were followed after the reintubation to register complications and outcome. RESULTS: A total of 1,152 extubated patients were included in the analysis. Three hundred thirty-six patients (29%) met the criteria for extubation failure. Extubation failure was independently associated with mortality (odds ratio, 3.29; 95% confidence interval, 2.19-4.93). One hundred eighty patients (16% of overall cohort) required reintubation within 48 hours after extubation. Median time from extubation to reintubation was 13 hours (interquartile range, 6-24 hours). Reintubation was independently associated with mortality (odds ratio, 5.18; 95% confidence interval, 3.38-7.94; P < .001). Higher mortality of reintubated patients was due to the development of complications after the reintubation. CONCLUSIONS: In a large cohort of scheduled extubated patients, one third of patients developed extubation failure, of whom half needed reintubation. Reintubation was associated with increased mortality due to the development of new complications after reintubation.

Early and small changes in serum creatinine concentrations are associated with mortality in mechanically ventilated patients.

Emerging evidence suggests that minor changes in serum creatinine concentrations are associated with increased hospital mortality rates. However, whether serum creatinine concentration (SCr) on admission and its change are associated with an increased mortality rate in mechanically ventilated patients is not known. We have conducted an international, prospective, observational cohort study enrolling adult intensive care unit patients under mechanical ventilation (MV). Recursive partitioning was used to determine the values of SCr at the start of MV (SCr0) and the change in SCr ([DeltaSCr] defined as the maximal difference between the value at start of MV [day 0] and the value on MV day 2 at 8:00 am) that best discriminate mortality. In-hospital mortality, adjusted by a proportional hazards model, was the primary outcome variable. A total of 2,807 patients were included; median age was 59 years and median Simplified Acute Physiology Score II was 44. All-cause in-hospital mortality was 44%. The variable that best discriminated outcome was a SCr0 greater than 1.40 mg/dL (mortality, 57% vs. 36% for patients with SCr0

Pandemic 2009 influenza A in Argentina: a study of 337 patients on mechanical ventilation.

RATIONALE: The rapid spread of the 2009 Influenza A (H1N1) around the world underscores the need for a better knowledge of epidemiology, clinical features, outcomes, and mortality predictors, especially in the most severe presentations. OBJECTIVES: To describe these characteristics in patients with confirmed, probable, and suspected viral pneumonia caused by 2009 influenza A (H1N1) admitted to 35 intensive care units with acute respiratory failure requiring mechanical ventilation in Argentina, between June 3 and September 7. METHODS: Inception-cohort study including 337 consecutive adult patients. Data were collected in a form posted on the Argentinian Society of Intensive Care website. MEASUREMENTS AND MAIN RESULTS: Proportions of confirmed, probable, or suspected cases were 39%, 8%, and 53% and had similar outcomes. APACHE II was 18 +/- 7; age 47 +/- 17 years; 56% were male; and 64% had underlying conditions, with obesity (24%), chronic obstructive respiratory disease (18%), and immunosupression (15%) being the most common. Seven percent were pregnant. On admission, patients had severe hypoxemia (Pa(O(2))/Fi(O(2)) 140 [87-200]), extensive lung radiologic infiltrates (2.87 +/- 1.03 quadrants) and bacterial coinfection, (25%; mostly with Streptococcus pneumoniae). Use of adjuvants such as recruitment maneuvers (40%) and prone positioning (13%), and shock (72%) and acute kidney injury requiring hemodialysis (17%), were frequent. Mortality was 46%, and was similar across all ages. APACHE II, lowest Pa(O(2))/Fi(O(2)), shock, hemodialysis, prone positioning, and S. pneumoniae coinfection independently predicted death. CONCLUSIONS: Patients with 2009 influenza A (H1N1) requiring mechanical ventilation were mostly middle-aged adults, often with comorbidities, and frequently developed severe acute respiratory distress syndrome and multiorgan failure requiring advanced organ support. Case fatality rate was accordingly high.

Airway pressure release ventilation versus assist-control ventilation: a comparative propensity score and international cohort study.

PURPOSE: To compare characteristics and clinical outcomes of patients receiving airway pressure release ventilation (APRV) or biphasic positive airway pressure (BIPAP) to assist-control ventilation (A/C) as their primary mode of ventilatory support. The objective was to estimate if patients ventilated with APRV/BIPAP have a lower mortality. METHODS: Secondary analysis of an observational study in 349 intensive care units from 23 countries. A total of 234 patients were included who were ventilated only with APRV/BIPAP and 1,228 patients who were ventilated only with A/C. A case-matched analysis according to a propensity score was used to make comparisons between groups. RESULTS: In logistic regression analysis, the most important factor associated with the use of APRV/BIPAP was the country (196 of 234 patients were from German units). Patients with coma or congestive heart failure as the reason to start mechanical ventilation, pH <7.15 prior to mechanical ventilation, and patients who developed respiratory failure (SOFA score >2) after intubation with or without criteria of acute respiratory distress syndrome were less likely to be ventilated with APRV/BIPAP. In the case-matched analysis there were no differences in outcomes, including mortality in the intensive care unit, days of mechanical ventilation or weaning, rate of reintubation, length of stay in the intensive care unit or hospital, and mortality in the hospital. CONCLUSIONS: In this study, the APRV/BIPAP ventilation mode is being used widely across many causes of respiratory failure, but only in selected geographic areas. In our patient population we could not demonstrate any improvement in outcomes with APRV/BIPAP compared with assist-control ventilation.

Outcomes of patients ventilated with synchronized intermittent mandatory ventilation with pressure support: a comparative propensity score study.

BACKGROUND: Few data are available regarding the benefits of one mode over another for ventilatory support. We set out to compare clinical outcomes of patients receiving synchronized intermittent mandatory ventilation with pressure support (SIMV-PS) compared with assist-control (A/C) ventilation as their primary mode of ventilatory support. METHODS: This was a secondary analysis of an observational study conducted in 349 ICUs from 23 countries. A propensity score stratified analysis was used to compare 350 patients ventilated with SIMV-PS with 1,228 patients ventilated with A/C ventilation. The primary outcome was in-hospital mortality. RESULTS: In a logistic regression model, patients were more likely to receive SIMV-PS if they were from North America, had lower severity of illness, or were ventilated postoperatively or for trauma. SIMV-PS was less likely to be selected if patients were ventilated because of asthma or coma, or if they developed complications such as sepsis or cardiovascular failure during mechanical ventilation. In the stratified analysis according to propensity score, we did not find significant differences in the in-hospital mortality. After adjustment for propensity score, overall effect of SIMV-PS on in-hospital mortality was not significant (odds ratio, 1.04; 95% CI, 0.77-1.42; P = .78). CONCLUSIONS: In our cohort of ventilated patients, ventilation with SIMV-PS compared with A/C did not offer any advantage in terms of clinical outcomes, despite treatment-allocation bias that would have favored SIMV-PS.

Técnica de oscilación forzada en la evaluación de la resistencia al flujo de tubos endotraqueales / Technique of pulled oscillation in the evaluation of the resistance to the flow of endotraqueales tubes

Los tubos endotraqueales (TET) utilizados para la provisión de ventilación mecánica (VM) agregan una resistencia adicional a la propia de la vía aérea. Ello puede resultar un factor relevante durante el proceso de destete de la VM. No ha sido comunicada la evaluación de la modificación de la resistencia de los TET mediante técnica de oscilación forzada (FOT) luego de su uso en VM. Objetivos. Cuantificar la resistencias en los TET sin uso y una vez retirados luego de ser utilizados para ventilación mecánica en pacientes críticos; evaluar la correlación de sus modificaciones con el tiempo de uso. Métodos. Determinación "basal" de la resistencia de los TET sin uso mediante FOT, sin otro flujo que el generado por el parlante. Medición con la misma técnica de las resistencias de 40 tubos post-extubación inmediata, durante un periodo de 4 meses. Resultados. Se evaluaron tubos de 7.5 a 9 mm de diámetro, con un tiempo de VM de 49(27-127) horas (mediana y 1-3 cuartillo). La resistencia en los TET usados fue mayor que la medida en los TET sin uso (1,98+-0,41 versus 1,51+-0,22 cmH2O.s.L.-1. La media del incremento en las resistencias fue 31,2+-20,3% (p<0.001). Las resistencias de los TET usados fueron similares a las de los TET nuevos de un 1mm de diámetro menor. No se encontró correlación entre tiempo de intubación e incremento de la resistencia en los TET. Concluciones. Se observa un incremento de las resistencias de los TET tras su uso en VM, respecto de los TET nuevos del mismo diámetro. El aumento es de magnitud tal que los TET utilizados en VM presentan resistencias similares a las de TET sin uso de diámetro de 1mm menor. Este hallazgo debe ser tenido en cuenta al momento de realizar las pruebas de ventilación espontánea para el destete de VM, ya que el incremento del trabajo respiratorio relacionado con la vía aérea artificial sería mayor al esperado para el diámetro del TET utilizado.

Técnica de oscilación forzada en la evaluación de la resistencia al flujo de tubos endotraqueales / Technique of pulled oscillation in the evaluation of the resistance to the flow of endotraqueales tubes

Los tubos endotraqueales (TET) utilizados para la provisión de ventilación mecánica (VM) agregan una resistencia adicional a la propia de la vía aérea. Ello puede resultar un factor relevante durante el proceso de destete de la VM. No ha sido comunicada la evaluación de la modificación de la resistencia de los TET mediante técnica de oscilación forzada (FOT) luego de su uso en VM. Objetivos. Cuantificar la resistencias en los TET sin uso y una vez retirados luego de ser utilizados para ventilación mecánica en pacientes críticos; evaluar la correlación de sus modificaciones con el tiempo de uso. Métodos. Determinación "basal" de la resistencia de los TET sin uso mediante FOT, sin otro flujo que el generado por el parlante. Medición con la misma técnica de las resistencias de 40 tubos post-extubación inmediata, durante un periodo de 4 meses. Resultados. Se evaluaron tubos de 7.5 a 9 mm de diámetro, con un tiempo de VM de 49(27-127) horas (mediana y 1-3 cuartillo). La resistencia en los TET usados fue mayor que la medida en los TET sin uso (1,98+-0,41 versus 1,51+-0,22 cmH2O.s.L.-1. La media del incremento en las resistencias fue 31,2+-20,3% (p<0.001). Las resistencias de los TET usados fueron similares a las de los TET nuevos de un 1mm de diámetro menor. No se encontró correlación entre tiempo de intubación e incremento de la resistencia en los TET. Concluciones. Se observa un incremento de las resistencias de los TET tras su uso en VM, respecto de los TET nuevos del mismo diámetro. El aumento es de magnitud tal que los TET utilizados en VM presentan resistencias similares a las de TET sin uso de diámetro de 1mm menor. Este hallazgo debe ser tenido en cuenta al momento de realizar las pruebas de ventilación espontánea para el destete de VM, ya que el incremento del trabajo respiratorio relacionado con la vía aérea artificial sería mayor al esperado para el diámetro del TET utilizado.(AU)

Técnica de oscilación forzada en la evaluación de la resistencia al flujo de tubos endotraqueales / Forced oscillation technique in the evaluation of flow resistance of endotracheal tubes

Los tubos endotraqueales (TET) utilizados para la provisión de ventilación mecánica (VM) agregan una resistencia adicional a la propia de la vía aérea. Ello puede resultar un factor relevante durante el proceso de destete de la VM. No ha sido comunicada la evaluación de la modificación de la resistencia de los TET mediante la Técnica de Oscilación Forzada (FOT) luego de su uso en VM. Objetivos: cuantificar las resistencias en los TET sin uso y una vez retirados luego de ser utilizados para ventilación mecánica en pacientes críticos; evaluar la correlación de sus modificaciones con el tiempo de uso. Métodos: determinación "basal" de la resistencia de los TET sin uso mediante FOT, sin otro flujo que el generado por el parlante. Medición con la misma técnica de las resistencias de 40 tubos post-extubación inmediata, durante un periodo de 4 meses. Resultados: se evaluaron tubos de 7.5 a 9 mm de diámetro, con un tiempo de VM de 49 (27 -127) horas (mediana y 1-3 cuartillo). La resistencia en los TET usados fue mayor que la medida en los TET sin uso (1,98±0,41 versus 1,51±0,22 cmH2O.s.L-¹). La media del incremento en las resistencias fue 31,2±20,3% (p<0,001). Las resistencias de los TET usados fueron similares a las de los TET nuevos de un 1mm de diámetro menor. No se encontró correlación entre tiempo de intubación e incremento de la resistencia en los TET. Conclusiones: se observa un incremento de las resistencias de los TET tras su uso en VM, respecto de los TET nuevos del mismo diámetro. El aumento es de magnitud tal que los TET utilizados en VM presentan resistencias similares a las de TET sin uso de diámetro 1 mm menor. Este hallazgo debe ser tenido en cuenta al momento de realizar las pruebas de ventilación espontánea para el destete de VM, ya que el incremento del trabajo respiratorio relacionado con la vía aérea artificial sería mayor al esperado para el diámetro del TET utilizado.

The endotracheal tubes (ETT) used for mechanical ventilation are an additional resistance to the normal airflow. This may be a relevant factor in the process of mechanical ventilation weaning. There have been no reports about the assessment through the Forced Oscillation Technique (FOT) of changes in the resistance to the air flow after the use of ETT for mechanical ventilation. Objectives: To quantify the resistance to air flow of new ETT before use and after use for mechanical ventilation in critically ill patients; to determine the correlation between changes in resistance with the time of use of the ETT. Methods: Determination of the baseline resistance of new ETT before use through the Forced Oscillation Technique, without any other flow than that generated by the loudspeaker. Measurement with the same technique of the resistance of 40 ETT after use over a period of four months. Results: Tubes with a diameter ranging from 7.5 to 9 mm were evaluated after having been used in mechanical ventilation for 49 (27-127) horas (median and1-3 quartil). The resistance of the used ETT was greater than that of the new, unused tubes (1.98± 0.41 versus 1.51± 0.22 cmH2O.s.L-¹). The average increase in resistance was 31.2%:± 20.3% (p < 0.001). The resistance measured in the used ETT was similar to that of new ETT having smaller diameters measuring 1 mm less. The correlation between intubation period and increasing resistance by ETT was not significant. Conclusions: ETT used in mechanical ventilation present a greater resistance to the air flow than the new, unused ETT of the same diameter. The increase in resistance of used ETT is similar to the resistance of new ETT measuring 1 mm less in diameter. This finding should be taken into account when spontaneous ventilation is tested at the moment of weaning mechanical ventilation, since the respiratory work related to the artificial airway would be greater than the expected respiratory work on the basis of the diameter...

Evolution of mechanical ventilation in response to clinical research.

RATIONALE: Recent literature in mechanical ventilation includes strong evidence from randomized trials. Little information is available regarding the influence of these trials on usual clinical practice. OBJECTIVES: To describe current mechanical ventilation practices and to assess the influence of interval randomized trials when compared with findings from a 1998 cohort. METHODS: A prospective international observational cohort study, with a nested comparative study performed in 349 intensive care units in 23 countries. We enrolled 4,968 consecutive patients receiving mechanical ventilation over a 1-month period. We recorded demographics and daily data related to mechanical ventilation for the duration of ventilation. We systematically reviewed the literature and developed 11 practice-change hypotheses for the comparative cohort study before seeing these results. In assessing practice changes, we only compared data from the 107 intensive care units (1,675 patients) that also participated in the 1998 cohort (1,383 patients). MEASUREMENTS AND MAIN RESULTS: In 2004 compared with 1998, the use of noninvasive ventilation increased (11.1 vs. 4.4%, P < 0.001). Among patients with acute respiratory distress syndrome, tidal volumes decreased (7.4 vs. 9.1 ml/kg, P < 0.001) and positive end-expiratory pressure levels increased slightly (8.7 vs. 7.7 cm H(2)O, P = 0.02). More patients were successfully extubated after their first attempt of spontaneous breathing (77 vs. 62%, P < 0.001). Use of synchronized intermittent mandatory ventilation fell dramatically (1.6 vs. 11%, P < 0.001). Observations confirmed 10 of our 11 practice-change hypotheses. CONCLUSIONS: The strong concordance of predicted and observed practice changes suggests that randomized trial results have advanced mechanical ventilation practices internationally.

Risk factors for extubation failure in patients following a successful spontaneous breathing trial.

BACKGROUND: To assess the factors associated with reintubation in patients who had successfully passed a spontaneous breathing trial. METHODS: We used logistic regression and recursive partitioning analyses of prospectively collected clinical data from adults admitted to ICUs of 37 hospitals in eight countries, who had undergone invasive mechanical ventilation for > 48 h and were deemed ready for extubation. RESULTS: Extubation failure occurred in 121 of the 900 patients (13.4%). The logistic regression analysis identified the following associations with reintubation: rapid shallow breathing index (RSBI) [odds ratio (OR), 1.009 per unit; 95% confidence interval (CI), 1.003 to 1.015]; positive fluid balance (OR, 1.70; 95% CI, 1.15 to 2.53); and pneumonia as the reason for initiating mechanical ventilation (OR, 1.77; 95% CI, 1.10 to 2.84). The recursive partitioning analysis allowed the separation of patients into different risk groups for extubation failure: (1) RSBI of > 57 breaths/L/min and positive fluid balance (OR, 3.0; 95% CI, 1.8 to 4.8); (2) RSBI of < 57 breaths/L/min and pneumonia as reason for mechanical ventilation (OR, 2.0; 95% CI, 1.1 to 3.6); (3) RSBI of > 57 breaths/L/min and negative fluid balance (OR, 1.4; 95% CI, 0.8 to 2.5); and (4) RSBI of < 57 breaths/L/min (OR, 1 [reference value]). CONCLUSIONS: Among routinely measured clinical variables, RSBI, positive fluid balance 24 h prior to extubation, and pneumonia at the initiation of ventilation were the best predictors of extubation failure. However, the combined predictive ability of these variables was weak.

Incidence, risk factors, and outcome of ventilator-associated pneumonia.

OBJECTIVE: The purpose of this study is to determine the incidence, risk factors, and outcome of ventilator-associated pneumonia (VAP). DESIGN: Prospective cohort. SETTING: Three hundred sixty-one intensive care units (ICUs) from 20 countries. PATIENTS AND PARTICIPANTS: Two thousand eight hundred ninety-seven patients mechanically ventilated for more than 12 hours. MEASUREMENTS AND RESULTS: Baseline demographic data, primary indication for mechanical ventilation, daily ventilator settings, multiple organ failure over the course of mechanical ventilation, and outcome were collected. Ventilator-associated pneumonia was present in 439 patients (15%). Patients with VAP were more likely to have chronic pulmonary obstructive disease, aspiration, sepsis, and acute respiratory distress syndrome. Mortality in patients with VAP was 38%. Factors associated with mortality were severity of illness, limited activity before the onset of mechanical ventilation and development of shock, acute renal failure, and worsening of hypoxemia during the period of mechanical ventilation. Case-control analysis showed no increased mortality in patients with VAP (38.1% vs 37.9%, P = .95) but prolonged duration of mechanical ventilation and ICU stay. CONCLUSION: In a large cohort of mechanically ventilated patients, VAP is more likely in patients with underlying lung disease (acute or chronic). Ventilator-associated pneumonia was associated with a significant increase in ICU length of stay but no increase in mortality.