Volume 4 Supplement 1

20th International Symposium on Intensive Care and Emergency Medicine

Open Access

Respiratory mechanics studied by multiple regression and the end-inspiratory pause technique during mechanical ventilation

  • MP Vassiliou1,
  • Ch Psarakis1,
  • A Amygdalou1,
  • K Kalopissi1,
  • M Moukas1 and
  • PK Behrakis1
Critical Care20004(Suppl 1):P113

DOI: 10.1186/cc833

Published: 21 March 2000

Full text

Aim of the study

In the present study, a comparative evaluation of the multiple linear regression analysis (MLRA) and the end-inspiratory pause technique (EIP) is attempted for the investigation of respiratory system (RS) mechanics during mechanical ventilation.

Methods

Airway pressure (Pao) and flow (V') data were digitally obtained from 25 ICU patients, who were mechanically ventilated (CMV mode) and under sedation and muscle relaxation. Volume (V) was calculated by numerical integration of V' . Data were analysed on a cycle per cycle basis with the aid of MLRA according to: Pao=PE + Ers.V + Rrs.V', where Ers represents the RS Elastance, Rrs the RS resistance and PE the end-expiratory pressure. Ers and Rrs were also calculated with the aid of the EIP, while end-expiratory pressure was measured on the actual Pao signal. Ers(EIP), Rrs(EIP) and PE(EIP) were used to reconstruct the pressure, according to EIP. Predicted Pao according to MLRA and EIP were correlated to the measured Pao. The error of correlations measured as the root mean square difference (RMSD) was used for the comparative evaluation of the two techniques. Student paired t-test was used for the comparison of the calculated mechanical coefficients (P=0.05).

Results

Results are presented in the table (*denotes statistically significant difference at P=0.05).

Conclusions

Both MLRA and EIP offer an almost equal and linear approach to respiratory mechanics during mechanical ventilation. MLRA gives more accurate results according to the better correlation (lower RMSD) of MLRA pressure than EIP pressure to the actually measured Pao.

Table

 

Ers (hPa/L)

Rrs (hPa/L/s)

PE (hPa)

RMSD (hPa)*

MLRA

29.15± 8.832

12.42± 4.346

2.10± 2.466

1.17± 0.590

EIP

28.06± 8.314

12.48± 4.157

1.86± 1.746

1.40± 0.738

Authors’ Affiliations

(1)
Pulmonary Function Laboratory, `St. Savas' Hospital and Laboratory of Experimental Physiology, Medical School, University of Athens

Copyright

© Current Science Ltd 2000

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