PURPOSE: The ARDS Network trial showed that use of low tidal volume (Vt) improved mortality, possibly by minimizing stretch-induced lung injury. We performed a cross-sectional analysis of all patients on mechanical ventilation (MV) in eight intensive care units (ICU) among four hospitals via remote electronic ICU monitoring. We compared Vt among patients stratified by ICU setting and by MV indication.
METHODS: Indication for MV, ventilator mode, Vt normalized by ideal body weight (Vt/IBW) and actual body weight (Vt/ABW), plateau-pressures (Pplateau), and PaO2/FiO2 were obtained. Data was analyzed with ANOVA.
RESULTS: Of 56 patients 5 were excluded (3 patients on PS; 1 on APRV; 1 on pressure A/C). Indications for MV were: 12 patients with ALI/ARDS, 14 with airway protection(AP), 11 with pneumonia(PNA), 9 with pulmonary edema(PE), 4 with non-thoracic surgery(Post SX), and 1 with asthma. ICU settings: 18 patients in MICU[ALI/ARDS=9; PNA=2, PE=3, AP=2, PostSX=1, Asthma=1], 17 in neuro-trauma ICU(NTICU)[AP=9, PNA=6, PE=2], 16 in surgical ICU(SICU)[PE=4, ALI/ARDS=3, PNA=3, Post SX=3, AP=3]. Figure 1 shows Vt(mean±SE) grouped by indication for MV. The Pplateau in 10 ALI/ARDS patients was 30.5±3.0 cmH2O (mean±SE)and the Vt/IBW (8.0±0.5 ml/kg) was higher(p=0.002) than 6ml/kg. Vt/IBW in ALI/ARDS was lower than in PostSX patients (p≤0.05). Figure 2 shows Vt(mean±SE) grouped by ICU settings. Vt/IBW in MICU was lower than in NTICU and SICU (p≤0.05). Vt/ABW was not different in any group of patients.
CONCLUSION: Tidal volume normalized by IBW for the ALI/ARDS group and all other groups in this study was above the goal from ARDS Network trial. Vt/IBW was lower in MICU compared with NTICU and SICU. This finding may be explained in part by the higher prevalence of ALI/ARDS in the MICU.
CLINICAL IMPLICATIONS: Despite the ARDS Network trial result, the low tidal volume strategy is not as widely used as we might expect. The benefit of this strategy in non-ALI/ARDS needs further study. Remote telemonitoring provides a novel approach to evaluate the role of low tidal volume strategy in all ventilated patients.
DISCLOSURE: Roberto Casal, None.