Intensive Care Medicine

, Volume 23, Issue 11, pp 1119–1124

Respiratory comfort of automatic tube compensation and inspiratory pressure support in conscious humans

  • J. Guttmann
  • H. Bernhard
  • G. Mols
  • A. Benzing
  • P. Hofmann
  • K. Geiger
  • C. Haberthür
  • D. Zappe
  • B. Fabry
Original

DOI: 10.1007/s001340050467

Cite this article as:
Guttmann, J., Bernhard, H., Mols, G. et al. Intensive Care Med (1997) 23: 1119. doi:10.1007/s001340050467

Abstract

Objective

To compare the new mode of ventilatory Support, which we call automatic tube compensation (ATC), with inspiratory pressure support (IPS) with respect to pereeption of respiratory comfort. ATC unloads the resistance of the endotracheal tube (ETT) in inspiration by increasing the airway pressure, and in expiration by decreasing the airway pressure aecording to the non-linear pressure-flow relationship of the ETT.

Design

Prospective randomized single blind cross-over study.

Setting

Laboratory of the Section of Experimental Anaesthesiology (Clinic of Anaesthesiology; University of Freiburg).

Subjects

Ten healthy volunteers.

Interventions

The subjects breathed spontaneously through an ETT of 7.5 mm i. d. Three different ventilatory modes, each with a PEEP of 5 cmH2O, were presented in random order using the Dräger Evita 2 ventilator with prototype software:
  1. (1)

    IPS (10 cmH2O,1 s ramp),

     
  2. (2)

    inspiratory ATC (ATC-in),

     
  3. (3)

    inspiratory and expiratory ATC (ATC-in-ex).

     

Measurements and main results

Immediately following a mode transition, the volunteers answered with a hand sign to show how they perceived the new mode compared with the preceding mode in terms of gain or loss in subjective respiratory comfort: “better”, “unchanged” or “worse”. Inspiration and expiration were investigated separately analyzing 60 mode transitions each. Flow rates were continuously measured. The transition from IPS to either type of ATC was perceived positively, i.e. as increased comfort, whereas the opposite transition from ATC to IPS was perceived negatively, i. e. as decreased comfort. The transition from ATC-in to ATC-in-ex was perceived positively whereas the opposite mode transition was perceived negatively in expiration only. Tidal volume was 1220 ± 404 ml during IPS and 1017 ± 362 ml during ATC. The inspiratory peak flow rate was 959 ± 78 ml/s during IPS and 1048 ± 197 ml/s during ATC.

Conclusions

ATC provides an increase in respiratory comfort compared with IPS. The predominant cause for respiratory discomfort in the IPS mode seems to be lung over-inflation.

Keywords

Automatic tube compensation (ATC) Inspiratory pressure support (IPS) Respiratory comfort 

Copyright information

© Springer-Verlag 1997

Authors and Affiliations

  • J. Guttmann
    • 1
  • H. Bernhard
    • 1
  • G. Mols
    • 1
  • A. Benzing
    • 1
  • P. Hofmann
    • 1
  • K. Geiger
    • 1
  • C. Haberthür
    • 2
  • D. Zappe
    • 2
  • B. Fabry
    • 2
  1. 1.Section of Experimental Anaesthesiology, Clinic of AnaesthesiologyUniversity of FreiburgFreiburgGermany
  2. 2.Division of Clinical Physiology, Clinic of Cardiac and Thoracic SurgeryUniversity HospitalBaselSwitzerland