The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts

VENTILATORMANAGEMENT OF ACUTE RESPIRATORY DISTRESS SYNDROME (ARDS) BEFORE AND AFTER ANNOUNCEMENTOF THE NIH ARDS NETWORK?S LOW TIDAL VOLUME (VT) VENTILATION STUDY

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RH Kallet MS RRT,JA Alonso RRT, JM Luce MD, Departments of Anesthesia, and Pulmonary CriticalCare Medicine, San Francisco General Hospital (SFGH)

Background:The NIH ARDS Network trial compared traditional VT ventilation at12 mL/kg to 6 mL/kg and demonstrated a significant mortality reduction (39 vs.31% respectively) in ARDS patients. We inquired whether these study resultsinfluenced physician ventilator management of ARDS patients.

Methods: Datawas abstracted from the medical records of 37 consecutive ARDS patients treatedat SFGH between May and October 1996 (during the first months of the Networkstudy) and 34 consecutive ARDS patients treated from March through August 2000(approximately 1 year after the study results were made public). No data wasused from any patient enrolled into an ARDS Network study, nor in any patientmanaged clinically using the ARDS Network protocol. Ventilation and arterialblood gas variables were recorded from a reference period on the day European-Americanconsensus conference criteria for ARDS were met, and for 2 days afterwards.Between group (1996 vs. 2000) comparisons were made using unpaired Bonferonnit-tests. Within-group, between-day comparisons were made using one-way analysisof variance and Tukey-Kramer tests. Alpha was set at 0.05.

Results: VTwas significantly lower and PEEP was significantly higher in patients managedafter release of the ARDS Network study results. There was a trend towards aprogressively lower VT over the first 3 days in patients managedduring 2000. The end-inspiratory plateau pressure (PPLAT) was notdifferent, but the change in airway pressure (D PAW: PPLAT? PEEP) was significantly lower on Day 0 and remained below 20 cm H2Oon subsequent days. Arterial carbon dioxide tension (PaCO2) was differentby Day 2. Arterial pH was not different between groups.

 

1996Day 0Day 1Day 2

VT(mL)

741± 137734 ± 129742 ± 128

PPLAT(cm H2O)

31.2 ± 9.4 29.8 ± 9.627.3 ± 7.2

PEEP (cm H2O)

6.9 ± 3.48.3 ± 3.78.0 ± 3.8

D PAW(cm H2O)

26.9 ± 10.521.5 ± 7.420.3 ± 7.6

PaCO2(mm Hg)

39.7 ± 11.437.6 ± 7.737.0 ± 7.0
 
2000Day 0Day 1Day 2
VT(mL)592 ± 139?546 ± 159?520 ± 160?

PPLAT(cm H2O)

27.3 ± 7.229.1 ± 8.427.8 ± 9.0

PEEP (cm H2O)

8.6 ± 3.2?10.6 ± 4.1?10.6 ± 3.8?

D PAW(cm H2O)

18.9 ± 6.4?18.5 ± 7.017.2 ± 7.5

PaCO2(mm Hg)

42.3 ± 7.9 40.2 ± 11.642.0 ± 9.4?

? p < 0.05 compared to corresponding1996 variable.

Conclusion:The ARDS Network study results appears to have influenced clinical practicein a Network study hospital. The higher PEEP level during 2000 may suggest anincreased awareness of the potential for added lung protection by maintainingan elevated end-expiratory lung volume. Therefore, these results alternativelymay signify a generalized awareness of lung protective strategies in ARDS patientsthat had increased over time.

OF-01-131

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