Abstract: Poster Presentations |

Volume Dependence of Respiratory Mechanics During Mechanical Ventilation In COPD Patients FREE TO VIEW

Argyro Amygdalou, MD; Miltiadis P. Vassiliou, MD; Christos Katsanos, MD; Christina Koubaniou, MD; Emanouil Mitrovassiliou, MD; Stavros H. Constantopoulos, MD, FCCP; Costas Mandragos, MD; Panagiotis K. Behrakis, MD, FCCP*
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Exper. Physiology Lab, Medical School, Athens, Greece


Chest. 2004;126(4_MeetingAbstracts):898S-b-899S. doi:10.1378/chest.126.4_MeetingAbstracts.898S-b
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PURPOSE:  To investigate the influence of VT size on respiratory mechanics during mechanical ventlation (MV) in COPD patients.

METHODS:  Airway pressure (Pao) and flow (V’) were recorded from 8 pts without respiratory disorder (WRD) and 8 pts with COPD exacerbation. They were under MV, sedation and muscle relaxation during measurements, performed at 6 levels of VT (300-800 ml) and 0 hPa of PEEPe. Data were analysed according to: Pao=EEP + E1.V+E2.V2 + k1.V’ + k2.V’.|V’| + k3.V.V’, where E1 & k1 are the linear coefficients of elastance and resistance, k2 the V’ dependence of resistance coefficient, E2 & k3 the volume dependence of elastance & resistance, respectively and EEP the end-expiratory pressure. Root Mean Square Difference (RMSD) of the regression was also calculated. All coefficients were compared between the two groups of pts and between the 6 levels of VT with the aid of two ways ANOVA with replication (p=0.05).

RESULTS:  -Significant higher values for all calculated coefficients (except E1) between WRD and COPD patients at all VT levels (k3 more negative in the COPD group). -k2 negative at all VT levels in the COPD group. -k3 negative at all VT levels in both groups. -E1 showed a tendency to increase on both groups. -E2 decreased significantly with VT increase in both groups. -k1 decreased non significantly with VT increase in both groups. -k2 decreased non significantly in the WRD group, while corresponding changes in the COPD group were not homogenous. -k3 turned significantly to more positive values with increasing VT. -EEP increased non-significantly with increasing VT in both groups. -RMSD increased with increasing VT in both groups, non-significantly in the COPD group.

CONCLUSION:  The present results suggest that tidal volume size influences strongly respiratory mechanics in mechanically ventilated COPD patients, specifically their dependencies on flow and volume.

CLINICAL IMPLICATIONS:  Careful monitoring, with the aid of the proposed non-linear model may help for better adjustment of the tidal volume in COPD patients under MV.

DISCLOSURE:  P.K. Behrakis, None.

Wednesday, October 27, 2004

12:30 PM - 2:00 PM




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