EBQ:ARDSnet Trial: Difference between revisions

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| fulltexturl=http://www.nejm.org/doi/full/10.1056/NEJM200005043421801
| fulltexturl=http://www.nejm.org/doi/full/10.1056/NEJM200005043421801
| pdfurl=http://www.nejm.org/doi/pdf/10.1056/NEJM200005043421801
| pdfurl=http://www.nejm.org/doi/pdf/10.1056/NEJM200005043421801
| status=Complete
}}
}}


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==Conclusion==
==Conclusion==
In patients with ALI/ARDS, lower tidal volumes of 6mL/kg ideal body weight reduces mortality and decreases length of time on mechanical ventilation.
In patients with ALI/ARDS, lower tidal volumes of 6mL/kg predicted body weight reduces mortality and decreases length of time on mechanical ventilation.


==Major Points==  
==Major Points==  
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*The trial was stopped early when patients in the low tidal volumes arm showed a significant decrease in mortality and more ventilator-free days compared to the traditional tidal volumes arm.
*The trial was stopped early when patients in the low tidal volumes arm showed a significant decrease in mortality and more ventilator-free days compared to the traditional tidal volumes arm.
==Guidelines==
==Guidelines==
See [[EBQ:Surviving_sepsis_2012|Surviving Sepsis 2012]]
See [[Sepsis]] for guideline recommendations


==Design==
==Design==
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===Baseline Characteristics===
===Baseline Characteristics===
*Mean age: 51.5 years
*Mean age: 51.5 years
*Gender: Female (40.5%)
*Sex: Female (40.5%)
*Ethnicity:
*Ethnicity:
**White: 73%
**White: 73%
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Patients monitored until day 28 or death for signs of system failure:
Patients monitored until day 28 or death for signs of system failure:
*Circulatory failure: SBP ≤90mmHg or need for vasopressor
*Circulatory failure: SBP ≤90mmHg or need for vasopressor
*Coagulation failure: platelets ≤80,000 mm3
*Coagulation failure: Platelets ≤80,000 mm3
*Hepatic failure: serum bilirubin ≥2mg/dL
*Hepatic failure: Bilirubin ≥2mg/dL
*Renal failure: serum creatinine ≥2mg/dL
*Renal failure: Creatinine ≥2mg/dL


==Outcomes==
==Outcomes==


===Primary Outcomes===
===Primary Outcomes===
*180-day mortality
**31.0% vs. 39.8% (RR 0.78; P=0.007)
*Ventilator-free days (Days 1-28)
**12 vs. 10 (P=0.007)
*Breathing without assistance by day 28
**65.7% vs. 55.0% (P<0.001; NNT 9)


===Secondary Outcomes===
===Secondary Outcomes===
*Days w/o non-pulmonary organ or system failure (Days 1 to 28)
**15 vs. 12 (P=0.006)
*Days w/o circulatory failure
**19 vs. 17 (P=0.004)
*Days w/o coagulation failure
**21 vs. 19 (P=0.004)
*Days w/o renal failure
**20 vs. 18 (P=0.005)
*Barotrauma (New PTX, pneumomediastinum, subcutaneous emphysema, pneumatocele)
**10% vs. 11% (P=0.43)
*Mean tidal volumes (ml/kg PBW)
**6.2 vs. 11.8 (P<0.001)
*Mean plateau pressures (cm H2O)
**25 vs. 33 (P<0.001)
*Peak inspiratory pressures (cm H2O)
**32 vs. 39 (P<0.05)


==Criticisms==
==Criticisms==
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==Funding==
==Funding==
The National Heart, Lung, and Blood Institute.
The National Heart, Lung, and Blood Institute.
==CME==
<quiz display=simple>
{According to the ARDSnet study, which of the following strategies is indicated?
|type="[]"}
-Tidal volumes of 10 ml/kg.
-Plateau pressure to be maintained at >45 cm
+Increase PEEP to achieve >90% oxygen saturation
||Tidal volumes should be 6 ml/kg. The plateau pressure should be checked and maintained at < 30 cm. Tidal volumes may need to be decreased to ensure safe plateau pressures. Patient-ventilator synchrony should be maintained because PEEP is “defeated” with over-breathing, coughing, and dys-synchrony.<ref>Manthous CA. avoiding circulatory complications during endotracheal intubation and initiation of positive pressure ventilation. J of Emerg Med 2010; 38:622-631. </ref>
+Maintain patient-ventilator synchrony
{Pulmonary question: Which of the following are potential complications from endotacheal intubation and ventilatory management?
|type="[]"}
+cardiac dysfunction and hypotension
||Hypotension, barotrauma, and ventilator-associated lung injury (VALI) are among the more important problems that occur after the institution of mechanical ventilation. Hypotension most often results from a combination of sedation, decreased venous return from elevated intrathoracic pressure, and diminished intravascular volume. Less often, adrenal insufficiency may play a role. Barotrauma results from elevated pulmonary pressures.  Pneumonia is a longer term potential complication of mechanical ventilation. ED clinicians can reduce the risk of ventilator-associated pneumonia (VAP) simply by elevating the patient's head 30 degrees, either by inclining the head of the bed upwards (ie, reverse Trendelenberg), or by placing the patient in a semirecumbent position (ie, not laying flat).
+barotrauma and pneumothorax
+elevated intracranial pressure
||Clinicians need to be aware that some abnormalities, such as an elevated PaCO2, need not be corrected to physiologic norms, and that attempts to do so increase the risk of VALI.
+ventilator-induced lung injury
||Clinicians can reduce the risk of barotrauma by minimizing plateau airway pressures. Reduced airway pressures, as well as reduced tidal volumes, also help minimize the risk of VALI.
+auto-PEEP
{Regarding mechanical ventilation, all of the following statements are TRUE, EXCEPT:
|type="()"}
-Acute respiratory failure can be defined by the presence of at least two of four criteria: 1) acute dyspnea, 2) PaO2<50mm at room air, 3) PaCO2>50mm, and 4) significant respiratory acidemia.
-One potential adverse effect of positive-pressure ventilation includes decreased venous return to the heart and decreased cardiac output.
-The best approach to use in patients with asthma is to use small tidal volumes (5-8ml/kg) and high inspiratory flow rates to reduce inspiratory time and peak airway pressures.
-When inadequate expiratory time is allowed in the COPD patient, air trapping is exacerbated with each inspiration and may eventually result in a high level of intrinsic PEEP (iPEEP or auto-PEEP) such that the inhaled volume cannot overcome the exhaled volume; the solution is to build adequate expiratory time into the ventilator settings.
+The ventilator rate for COPD patients should be titrated as high as possible with I/E ratios of 1:1.
||The rate should be kept as low as possible for patients with COPD, and the expiratory time should be maximized with I/E ratios to 1:3 or 1:4. The tidal volume also should be minimized to reduce exhaled volumes, and COPD patients may require higher flow rates (>100/min) during inspiration to minimize inspiratory time. Low tidal volumes, I/E ratios of 1:3 or 1:4, and high inspiratory flow rates reduces iPEEP or auto-PEEP.
</quiz>
==Sources==
==Sources==
<references/>
<references/>


[[Category:Pulm]][[Category:Critical Care]][[Category:EBQ]]
[[Category:Pulmonary]][[Category:Critical Care]][[Category:EBQ]]

Revision as of 02:19, 14 July 2016

Complete Journal Club Article
Brower RG, et al. "Ventilation With Lower Tidal Volumes As Compared With Traditional Tidal Volumes For Acute Lung Injury And The Acute Respiratory Distress Syndrome". The New England Journal of Medicine. 2000. 342(18):1301-1308.
PubMed Full text PDF

Clinical Question

Does a lung protective strategy of low tidal volumes in patients with Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS) decrease mortality and ventilator-free days when compared to traditional ventilation strategies.

Conclusion

In patients with ALI/ARDS, lower tidal volumes of 6mL/kg predicted body weight reduces mortality and decreases length of time on mechanical ventilation.

Major Points

  • Acute Respiratory Distress Syndrome results from alveolar damage and barotrauma are associated with elevated plateau pressures and higher tidal volume ventilations
  • The trial was stopped early when patients in the low tidal volumes arm showed a significant decrease in mortality and more ventilator-free days compared to the traditional tidal volumes arm.

Guidelines

See Sepsis for guideline recommendations

Design

  • Multicenter, randomized trial of 861 patients in parallel-group in 10 university-affiliated ARDSNet centers
    • Low tidal volumes: Starting at 6ml/kg PBW and plateau pressure ≤30cmH2O (n=432)
    • Traditional tidal volumes: starting at 12ml/kg PBW and plateau pressure of ≤50cmH2O (n=429)
  • Enrollment: March 1996 to March 1999 (terminated early after the fourth interim analysis)
  • Follow-up: 180 days or until home breathing independently

Population

Inclusion Criteria

  • Age ≥18 years
  • Receiving mechanical ventilation
  • Diagnosis of ALI/ARDS ≤36h prior to enrollment; defined as:
    • Acute decrease in PaO2/FiO2ratio to ≤300
    • CXR: Bilateral pulmonary infiltrates
    • PCWP of ≤18mmHg without evidence of left atrial hypertension

Exclusion Criteria

  • Pregnancy
  • Increased ICP, neuromuscular disease imparing spontaneous breathing, sickle cell disease, or severe chronic respiratory disease
  • Weight more than 1kg/cm of height
  • Burns >30% of BSA
  • Estimated 6-month mortality rate >50%
  • History of bone marrow or lung transplantation
  • Child-Pugh class C liver disease
  • Participation in other trials w/in 30 days

Baseline Characteristics

  • Mean age: 51.5 years
  • Sex: Female (40.5%)
  • Ethnicity:
    • White: 73%
    • Black: 17.5%
    • Hispanic: 6%
  • APACHE III score: 82.5
  • Mean PaO2:FiO2: 136
  • Mean tidal volume: 670 mL
  • Mean minute ventilation: 13.4 vs. 12.7 L/min (P=0.01)

Interventions

Patients randomly assigned to receive mechanical ventilation (volume-assist-control mode) with following strategies for tidal volume:

  • Low tidal volumes (lung protective strategy): Starting at 6ml/kg PBW to maintain plateau pressure ≤30cm H2O (n=432)
  • Traditional tidal volumes: Starting at 12ml/kg to maintain plateau pressure of ≤50cm H2O (n=429)

Patients monitored until day 28 or death for signs of system failure:

  • Circulatory failure: SBP ≤90mmHg or need for vasopressor
  • Coagulation failure: Platelets ≤80,000 mm3
  • Hepatic failure: Bilirubin ≥2mg/dL
  • Renal failure: Creatinine ≥2mg/dL

Outcomes

Primary Outcomes

  • 180-day mortality
    • 31.0% vs. 39.8% (RR 0.78; P=0.007)
  • Ventilator-free days (Days 1-28)
    • 12 vs. 10 (P=0.007)
  • Breathing without assistance by day 28
    • 65.7% vs. 55.0% (P<0.001; NNT 9)

Secondary Outcomes

  • Days w/o non-pulmonary organ or system failure (Days 1 to 28)
    • 15 vs. 12 (P=0.006)
  • Days w/o circulatory failure
    • 19 vs. 17 (P=0.004)
  • Days w/o coagulation failure
    • 21 vs. 19 (P=0.004)
  • Days w/o renal failure
    • 20 vs. 18 (P=0.005)
  • Barotrauma (New PTX, pneumomediastinum, subcutaneous emphysema, pneumatocele)
    • 10% vs. 11% (P=0.43)
  • Mean tidal volumes (ml/kg PBW)
    • 6.2 vs. 11.8 (P<0.001)
  • Mean plateau pressures (cm H2O)
    • 25 vs. 33 (P<0.001)
  • Peak inspiratory pressures (cm H2O)
    • 32 vs. 39 (P<0.05)

Criticisms

Funding

The National Heart, Lung, and Blood Institute.

Sources