Skip to main content
SpringerLink
Log in

Patient State Index (PSI) measures depth of sedation in intensive care patients

  • Original
  • Published:
Intensive Care Medicine Aims and scope Submit manuscript

Abstract

Objective

To investigate whether the electroencephalogram (EEG)-based Patient State Index (PSI) indicates the level of sedation as measured by Ramsay score in intubated and mechanically ventilated patients in the ICU.

Design

Prospective, single-blinded observer study.

Setting

Surgical intensive care unit.

Patients

Forty-one consecutive adult patients requiring intubation and ventilation during intensive care therapy.

Measurements and results

Following skin preparation with alcohol and placement of EEG electrodes, PSI was recorded while patients were ventilated and sedated with constant drug infusion rates. After 30 min, the level of sedation was measured by an assessor, who was blinded to PSI values, using the Ramsay sedation score. For analysis, the mean of PSI values measured during the last minute before clinical assessment of sedation was calculated. General Linear Model (GLM) analysis revealed significant differences between the PSI values at different levels of sedation as measured by the Ramsay score, except for the differentiation of level 5 from levels 4 and 6 (p>0.3) and level 2 from level 3, where only a trend was reached (p=0.077). The prediction probability of PSI was 0.920±0.037.

Conclusion

As the high prediction probability and the analysis of paired comparisons suggest, PSI may be used to quantify the level of propofol/sufentanil sedation in ICU patients. Further studies are required to test whether these promising results can be verified for other drug combinations.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1

Similar content being viewed by others

References

  1. Smith WD, Dutton RC, Smith NT (1996) Measuring the performance of anesthetic depth indicators. Anesthesiology 84:38–51

    Article  CAS  Google Scholar 

  2. Gugino LD, Chabot RJ, Prichep LS, John ER, Formanek V, Aglio LS (2001) Quantitative EEG changes associated with loss and return of consciousness in healthy adult volunteers anaesthetized with propofol or sevoflurane. Br J Anaesth 87:421–428

    Article  CAS  Google Scholar 

  3. John ER, Prichep LS, Kox W, Valdes-Sosa P, Bosch-Bayard J, Aubert E, Tom M, diMichele F, Gugino LD (2001) Invariant reversible QEEG effects of anesthetics. Conscious Cogn 10:165–183

    Article  CAS  Google Scholar 

  4. Prichep LS, John ER, Gugino LD, Kox W, Chabot RJ (2000) Quantitative EEG assessment of changes in the level of sedation/hypnosis during surgery under general anaesthesia. In: Jordan C, Vaughan DJA, Newton DEF (eds) Memory and awareness in anaesthesia. Imperial College Press, London, pp 97–107

  5. Nasraway SA, Wu EC, Kelleher RM, Yasuda CM, Donnelly AM (2002) How reliable is the Bispectral Index in critically ill patients? A prospective, comparative, single-blinded observer study. Crit Care Med 30:1483–1487

    Article  Google Scholar 

  6. Riker RR, Fraser GL, Simmons LE, Wilkins ML (2001) Validating the Sedation-Agitation Scale with the Bispectral Index and Visual Analog Scale in adult ICU patients after cardiac surgery. Intensive Care Med 27:853–858

    Article  CAS  Google Scholar 

  7. Vivien B, Di Maria S, Quattara A, Langeron O, Coriat P, Riou B (2003) Overestimation of Bispectral Index in sedated intensive care unit patients revealed by administration of muscle relaxant. Anesthesiology 99:9-17

    Article  Google Scholar 

  8. Schneider G, Gelb AW, Schmeller B, Tschakert R, Kochs E (2003) Detection of awareness in surgical patients with EEG-based indices—Bispectral Index (BIS) and Patient State Index (PSI). Br J Anaesth 91:329–335

    Article  CAS  Google Scholar 

  9. Ramsay MA, Savege TM, Simpson BR, Goodwin R (1974) Controlled sedation with alphaxalone-alphadolone. BMJ 2:656–659

    Article  CAS  Google Scholar 

  10. Carrasco G (2000) Instruments for monitoring intensive care unit sedation. Critical Care 4:217–225

    Article  CAS  Google Scholar 

Download references

Acknowledgements

The authors thank Warren D. Smith, PhD (Professor, Biomedical Engineering Program, California State University, Sacramento, CA) for providing PKMACRO software and the helpful support in installation and use of the programme. The authors thank the nurses of the anaesthesiology intensive care unit for their support.

Author information

Authors and Affiliations

  1. Department of Anaesthesiology, Technische Universität München, Klinikum rechts der Isar, Ismaningerstrasse 22, 81675, Munich, Germany

    Gerhard Schneider, Susanne Heglmeier, Jürgen Schneider, Gunter Tempel & Eberhard F. Kochs

Authors
  1. Gerhard Schneider
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Susanne Heglmeier
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Jürgen Schneider
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Gunter Tempel
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Eberhard F. Kochs
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Gerhard Schneider.

Additional information

This work was financed from departmental sources and supported by a grant from B. Braun AG, Melsungen, Germany.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Schneider, G., Heglmeier, S., Schneider, J. et al. Patient State Index (PSI) measures depth of sedation in intensive care patients. Intensive Care Med 30, 213–216 (2004). https://doi.org/10.1007/s00134-003-2092-5

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s00134-003-2092-5

Keywords

Search

Navigation