Transcript PowerPoint Slides

Contemporary Ventilator Management
in Patients with and at risk of ALI/ARDS
Carl Hinkson, MS, RRT-ACCS, NPS, FAARC
Respiratory Care Department
Harborview Medical Center
Seattle, WA
Program Objectives

Identify the research question of the study.

Identify the study design.

Discuss the main results of the study.

Discuss the implication of the study on patient care.
April 2013 RESPIRATORY CARE Journal Webcast
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Background
• Patients with ALI/ARDS benefit from low tidal
volume ventilation with limitation of plateau
pressures
• Despite several studies, the strategy to best
manage PEEP in ALI/ARDS remains elusive
• It is unclear if there is any benefit to
ventilating patients without ALI/ARDS with
low tidal volume ventilation
Background
• What is the research question?
– What variables impact administered tidal volume
– What is the impact of ALI/ARDS on outcomes
– Whether or not clinicians are consistently using low tidal
volume ventilation after the 2000 ARDS Network study
– The authors hypothesized ventilating with a low tidal
volume would be associated with less post intubation
ALI/ARDS
• Any concerns about COI?
– This research was not directly funded. Nor did any authors
have any direct conflict of interests. Some authors
reported receiving research funds or consulting fee not
related to this topic
Methods
• Secondary analysis of the Lung Injury
Prevention Score (LIPS) study
– Observational, 22 center cohort
– Conducted between March to August 2009
• 19 centers prospectively collected data
• 3 centers retrospectively collected data
Methods
– Inclusion criteria
• > 18 years of age
• 1 or more risk factor for ALI/ARDS
–
–
–
–
–
–
–
Sepsis
Shock
Pancreatitis
Pneumonia
Aspiration
High-risk trauma
High-risk surgery
• Admitted through ED or operating rooms
Methods
• Exclusion criteria
– Excluded if they developed ALI/ARDS within six
hours of assessment
– Transferred from an outside institution
– Died in the ED
– Admitted for palliation (comfort care)
– Re-admitted during the study period
– Patients who never received mechanical
ventilation or received mechanical ventilation for
< 1 day
Methods
• Data collected
– Baseline characteristics
– Sociodemographics
– Comorbidities
• Data was collected within first 6 hours of evaluation
• Initial ventilator settings, parameters, volumes, and
pressures
– For subjects that developed post intubation ALI/ARDS the
first set of ventilator data was collected after the diagnosis
was made.
Methods
• Outcomes
– Primary
• Initial tidal volume & PEEP in:
– Patients who never developed ALI/ARDS,
– Patients intubated because of ALI/ARDS
– Patients who developed ALI/ARDS after intubation
• Researchers used the American-European Consensus
Conference definition
– Secondary
• Development of ALI/ARDS after initial intubation
• Hospital outcomes: ventilator free days & mortality
Methods
• Statistical Analysis
– Kolmogorov-Sminov test for normal distribution
– Student’s t-test or Mann-Whitney for continuous variables
– Categorical variables compared using Chi-squared or
Fischer’s exact test
– One-way ANOVA for variation in tidal volume settings
– Multivariate analysis was done with logistic regression
(one for tidal volume, one for PEEP)
– Significance (alpha/α) was 0.05, all test were two-sided
– Data was expressed as median with interquartile ranges
Results
Results
Results
Results
Results
Results
Results
Results
Results
Results
Results
Results – Inter-center variation in VT among all MV pts
ARDSnet
target VT
Results – Inter-center variation in VT among MV pts
that did not develop ALI/ARDS
ARDSnet
target VT
Results – Inter-center variation in VT among MV pts
intubated for ALI/ARDS
ARDSnet
target VT
Results – Inter-center variation in VT among MV pts with postintubation ALI/ARDS
ARDSnet
target VT
Discussion
• What do these finding mean?
– Application of low tidal volume is variable, but clinicians are
getting better about using low tidal volume ventilation for
ALI/ARDS
– Sicker patients were more likely to receive low VT ventilation
– Ventilator settings and delivering VT < 8mL/kg PBW is not
associated with development of post-intubation ALI/ARDS or
outcomes
– Development of post-intubation ALI/ARDS was associated with
more resource utliziation
– Subjects were more likely to receive low VT if they were male,
taller, and less obese.
– Shorter & heavier subjects tended to receive VT ≥8mL/kg PBW
Discussion
• What are the study limitations?
– Analysis is based from initial ventilator check
– The study was under-powered to detect outcome
differences
– Study limited by observational nature
• What additional work is needed in this area?
– Why patients who develop ARDS post intubation consume
more resources
– Prospective research the role of ventilator settings on
post-intubation ARDS
Editorial
• From Robert P Dickson, MD
– Main limitation of this study “snapshot” nature of the
ventilator data
– Difficult to ascertain if subjects received low VT ventilation
based only on ventilator data
– The absolute difference between the “at intubation” and
“post-intubation” ALI/ARDS was small
– Message of lower tidal volume from ARDSnet trial seems
to have gotten out
Conclusions
• What are the authors’ conclusions?
– Improved, but not ideal adherence to lower VT ventilation
– Variation in ventilator management did not affect
outcomes
– Post-intubation ARDS was associated with greater resource
utilization
• What is the take-home message?
– You should still use low VT ventilation for ARDS pts
– Assure that VT is calculated from PBW not ABW