13 Nov 09
Posted in Mechanical ventilation at 2:27 by Laci
By C Teixeira, N da Silva, A Savi, S Rios Vieira, L Nasi, G Friedman et al
Crit Care Med – published ahead of print
To evaluate the predictive value of central venous saturation to detect extubation failure in difficult-to-wean patients.
Design
Cohort, multicentric, clinical study.
Setting
Three medical-surgical intensive care units.
Patients
All difficult-to-wean patients (defined as failure to tolerate the first 2-hr T-tube trial), mechanically ventilated for >48 hrs, were extubated after undergoing a two-step weaning protocol (measurements of predictors followed by a T-tube trial). Extubation failure was defined as the need of reintubation within 48 hrs.
Interventions
The weaning protocol evaluated hemodynamic and ventilation parameters, and arterial and venous gases during mechanical ventilation (immediately before T-tube trial), and at the 30th min of spontaneous breathing trial.
Measurements and main results
Seventy-three patients were enrolled in the study over a 6-mo period. Reintubation rate was 42.5%. Analysis by logistic regression revealed that central venous saturation was the only variable able to discriminate outcome of extubation. Reduction of central venous saturation by >4.5% was an independent predictor of reintubation, with odds ratio of 49.4 (95% confidence interval = 12.1-201.5), a sensitivity of 88%, and a specificity of 95%. Reduction of central venous saturation during spontaneous breathing trial was associated with extubation failure and could reflect the increase of respiratory muscles oxygen consumption.
Conclusions
Central venous saturation was an early and independent predictor of extubation failure and may be a valuable accurate parameter to be included in weaning protocols of difficult-to-wean patients.
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08 Nov 09
Posted in COPD, Mechanical ventilation at 19:43 by Laci
By M Wildman, C Sanderson, J Groves, B Reeves, J Ayres, D Harrison, D Young and K Rowan
QJM 2009 102(6):389-399 http://qjmed.oxfordjournals.org/cgi/content/full/102/6/389
Decisions about the intensity of treatment for patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are influenced by predictions about survival and quality of life. Evidence suggests that these predictions are poorly calibrated and tend to be pessimistic.
Aim
The aim of this study was to develop an outcome prediction model for COPD patients to support treatment decisions.
Methods
A prospective multi-centre cohort study in Intensive Care Units (ICU) and Respiratory High Dependency Units (RHDU) in the UK recruited patients aged 45 years and older admitted with an exacerbation of obstructive lung disease. Data were collected on patientsí characteristics prior to ICU admission, and on their survival and quality of life after 180 days. An outcome prediction model was developed using multivariate logistic regression and bootstrapping.
Results
Ninety-two ICUs (53% of those in the UK) and three RHDUs took part. A total of 832 patients were recruited. Cumulative 180-day mortality was 37.9%. Using data available at the time of admission to the units, a prognostic model was developed which had an estimated area under the receiver operating characteristic curve (ëcí) of 74.7% after bootstrapping that was more discriminating than the clinicians (P = 0.033) and was well calibrated.
Discussion
This study has produced an outcome prediction model with slightly better discrimination and much better calibration than the participating clinicians. It has the potential to support risk adjustment and clinical decision making about admission to intensive care.
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17 Oct 09
Posted in Mechanical ventilation at 1:32 by Laci
By M de Wit, K Miller, D Green, H Ostman, C Gennings, S Epstein
Crit Care Med 2009;37:2740-2745
To determine whether high rates of ineffective triggering within the first 24 hrs of mechanical ventilation (MV) are associated with longer MV duration and shorter ventilator-free survival (VFS).
Design
Prospective cohort study.
Setting
Medical intensive care unit (ICU) at an academic medical centre.
Patients
Sixty patients requiring invasive MV.
Interventions
None.
Measurements
Patients had pressure-time and flow-time waveforms recorded for 10 mins within the first 24 hrs of MV initiation. Ineffective triggering index (ITI) was calculated by dividing the number of ineffectively triggered breaths by the total number of breaths (triggered and ineffectively triggered). A priori, patients were classified into ITI >=10% or ITI <10%. Patient demographics, MV reason, codiagnosis of chronic obstructive pulmonary disease (COPD), sedation levels, and ventilator parameters were recorded.
Measurements and main results
Sixteen of 60 patients had ITI >=10%. The two groups had similar characteristics, including COPD frequency and ventilation parameters, except that patients with ITI >=10% were more likely to have pressured triggered breaths (56% vs. 16%, p = .003) and had a higher intrinsic respiratory rate (22 breaths/min vs. 18, p = .03), but the set ventilator rate was the same in both groups (9 breaths/min vs. 9, p = .78). Multivariable analyses adjusting for pressure triggering also demonstrated that ITI >=10% was an independent predictor of longer MV duration (10 days vs. 4, p = .0004) and shorter VFS (14 days vs. 21, p = .03). Patients with ITI >=10% had a longer ICU length of stay (8 days vs. 4, p = .01) and hospital length of stay (21 days vs. 8, p = .03). Mortality was the same in the two groups, but patients with ITI >=10% were less likely to be discharged home (44% vs. 73%, p = .04).
Conclusions
Ineffective triggering is a common problem early in the course of MV and is associated with increased morbidity, including longer MV duration, shorter VFS, longer length of stay, and lower likelihood of home discharge.
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12 Oct 09
Posted in Mechanical ventilation, VAP at 14:04 by Laci
By W Melsen, M Rovers, M Bonten
Crit Care Med 2009; 37:2709-2718
To determine the attributable mortality of ventilator-associated pneumonia in a systematic review and meta-analysis of observational studies. Ventilator-associated pneumonia is generally believed to increase the mortality of patients. This notion is predominantly based on the results of observational studies.
Data source
We performed a systematic search strategy using PubMed, Web of Science, and Embase from their inception through February 2007. In addition, a reference and related article search was performed.
Study selection
Studies were included if they reported mortality rates of patients with and without ventilator-associated pneumonia.
Data extraction and synthesis
Fifty-two studies with a total of 17,347 patients met the inclusion criteria. Pooling of all studies resulted in relative risk of 1.27 (95% Confidence Interval = 1.15-1.39), but heterogeneity was considerable (I2 statistic = 69%). The origin of heterogeneity could not be explained by differences in study design, study quality, and diagnostic approach. However, heterogeneity was limited for studies investigating only trauma patients (I2 = 1.3%) or patients with acute respiratory distress syndrome (I2 = 0%), with estimated relative risk of 1.09 (95% Confidence Interval = 0.87-1.37) among trauma patients and 0.86 (95% Confidence Interval = 0.72-1.04) among patients with acute respiratory distress syndrome.
Conclusions
There is no evidence of attributable mortality due to ventilator-associated pneumonia in patients with trauma or acute respiratory distress syndrome. However, in other nonspecified patient groups, there is evidence for attributable mortality due to ventilator-associated pneumonia, but this could not be quantified due to heterogeneity in study results. More detailed studies, allowing subgroup analyses, are needed to determine the attributable mortality of ventilator-associated pneumonia in these patient populations.
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