The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

ABILITY TO MAINTAIN LUNG PROTECTIVE VENTILATION GOALS USING THE NIH ACUTE RESPIRATORY DISTRESS SYNDROME NETWORK?S (ARDS-Net) LOW TIDAL VOLUME (VT) PROTOCOL DURING CLINICAL MANAGEMENT OF ACUTE LUNG INJURY (ALI)

RH Kallet MS RRT, JM Luce MD, RM Jasmer MD. Departments of Anesthesia and Pulmonary Critical Care Medicine, San Francisco General Hospital (SFGH)


Background:
The NIH ARDS-Net trial demonstrated a significant reduction in mortality in ALI/ARDS patients who received mechanical ventilation with a VT of 6 mL/kg predicted body weight (PBW) compared to those who received a VT of 12 mL/kg (39.8 vs. 31% respectively). SFGH has adapted the ARDS-Net low VT protocol for routine clinical management of ALI/ARDS patients. We inquired if the study target goals for lung protective ventilation could be maintained during clinical practice. 

Methods
: We gathered data on all 180 ALI/ARDS patients managed clinically with the ARDS-Net protocol between September 2000 and June 2003. Ventilator parameters were extracted from 2 reference ventilator checks on days 1,3,7 and 14 of protocol management only when the patient was on time-cycled, volume or pressure-regulated ventilation. Data included VT in mL/kg predicted body weight (PBW), end-inspiratory plateau pressure (Pplat), positive end-expiratory pressure (PEEP), Pplat-PEEP, fractional oxygen concentration (FIO2), respiratory rate (f), arterial oxygen tension (PaO2), arterial carbon dioxide tension (PaCO2) and arterial pH. Data were analyzed using one-way ANOVA and Tukey-Kramer multiple comparisons tests. Alpha was set at 0.05.

Results
: Lung protective ventilation goals were generally maintained during the first 2-weeks of protocol management. Patients requiring mechanical ventilation for > 1 week had a higher PaCO2 at the same f and VT suggesting a tendency towards a permissive hypercapnic strategy during the subacute phase of ALI/ARDS. In addition, clinicians tended to liberalize PaO2 limits compared to the management during the ARDS-Net study.

Variable Day 1 Day 3 Day 7 Day 14
N 348 285 197 109
VT (mL/kg) 6.15 ± 1.03 6.24 ± 1.04 6.41 ± 1.14 6.30 ± 1.54
Pplat (cm H2O) 27.3 ± 6.7 26.8 ± 7.5 26.5 ± 7.7 27.5 ± 8.9
PEEP (cm H2O) 9.9 ± 3.2 9.5 ± 3.4 8.7 ± 3.3 8.4 ± 3.5
Pplat-PEEP (cm H2O) 17.4 ± 5.8 17.3 ± 6.0 17.8 ± 6.4 19.1 ± 7.1
f 26.9 ± 7.2 26.3 ± 6.7 25.8 ± 7.7 25.3 ± 8.0
FIO2 0.60 ± 0.18 0.55 ± 0.16* 0.52 ± 0.15* 0.49 ± 0.16
pH 7.37 ± 0.08 7.38 ± 0.07 7.39 ± 0.06* 7.38 ± 0.06
PaCO2 mm Hg 40.6 ± 7.8 42.7 ± 7.4* 45.8 ± 10 45.7 ± 9.0
PaO2 mm Hg 85.1 ± 23.9 85.1 ± 22.3 86.8 ± 26.4 92.8 ± 26.2


*p < 0.05 compared to Day 1; † p < 0.05 compared to Day 3.


CONCLUSION:
Lung protective ventilation goals can be maintained successfully over time when the ARDS-Net low VT protocol is used to clinically manage ALI/ARDS patients.

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