Skip to main content
SpringerLink
Log in

Venous admixture (Qva/Q) and true shunt (Qs/Qt) in ARF patients: Effects of PEEP at constant FIO2

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

Abstract

Venous admixture (Qva/Q) in ARF patients is due to both true right to left shunt (Qs/Qt: perfusion of truly unventilated areas) and to maldistribution ((Qva-Qs)/Qt: effects of unevenness of ventilation/perfusion ratio). Using the retention rate of sulphur hexafluoride we determined the effects of PEEP on Qs/Qt and (Qva-Qs)/Qt at a constant FIO2 for each patient (0.57±0.19 SD, range 0.4–0.95). Eleven patients with ARF (treated either by CPPV or CPAP) were studied on 16 occasions. Each measurement was repeated at two levels of PEEP, 5 cm H2O below and 5 cm H2O above the patient's clinically determined PEEP level. The increase in PEEP resulted in: — a decrease in Qva/Q (from 0.37±0.13 to 0.27±0.12,p<0.01); — a parallel decrease in Qs/Qt (from 0.29±0.16 to 0.22±0.14,p<0.01); there was a positive correlation between Qva/Q and Qs/Qt changes (r=0.53,p<0.05). No significant variation was demonstrated in (Qva-Qs)/Qt (from 0.074±0.045 to 0.054±0.048). On the other hand there was a negative correlation between the fraction of Qva/Q due to the maldistribution and FIO2: (Qva-Qs)/Qva=0.75–0.86 FIO2 (r=0.74,p<0.01). We conclude that: PEEP decreased Qva/Q mainly through changes in Qs/Qt but did not have a definite effect on (Qva-Qs)/Qt. Maldistribution was responsible for a significant portion of Qva/Q in those ARF patients tolerating a relatively low FIO2 (0.4–0.6).

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

Similar content being viewed by others

References

  1. Cane RD, Shapiro BA, Harrison RA, Steiner MC, Kavanaugh J (1980) Minimizing errors in intrapulmonary shunt calculations. Crit Care Med 8:294

    PubMed  Google Scholar 

  2. Dantzker DR, Brook JC, Dehart P, Lynch JP, Weg JG (1979) Ventilation-perfusion distributions in the adult respiratory distress syndrome. Am Rev Respir Dis 120:1039

    PubMed  Google Scholar 

  3. Dantzker DR, Wagner PD, West JB (1975) Instability of lung units with low VA/Q ratios during O2 breathing. J Appl Physiol 38:886

    Google Scholar 

  4. Ellman H, Dembin H (1982) Lack of adverse hemodynamic effects of PEEP in patients with acute respiratory failure. Crit Care Med 10:706

    PubMed  Google Scholar 

  5. Falke KJ, Pontoppidan H, Kumar A, Leith D, Geffin B, Laver MB (1972) Ventilation with end expiratory pressure in acute lung disease. J Clin Invest 51:2315

    PubMed  Google Scholar 

  6. Gallagher TJ, Klain MM, Carlon GC (1982) Present status of high frequency ventilation. Crit Care Med 10:613

    PubMed  Google Scholar 

  7. Gattinoni L, Kolobow T, Tomlinson T, Iapichino G, Samaja M, White D, Pierce J (1978) Low frequency positive pressure ventilation with extracorporeal carbon dioxide removal (LFPPV-ECCO2R): an experimencal study. Anesth Analg 57:470

    PubMed  Google Scholar 

  8. Lachmann B, Haendley B, Shulz H, Jonson B (1980) Improved arterial oxygenation, CO2 elimination, compliance and decreased barotrauma following changes of volume generated PEEP ventilation with inspiratory/expiratory (I/E) ratio of 1/2 to pressure generated ventilation with I/E ratio of 4/1 in patients with severe adult respiratory distress syndrome (ARDS). Intensive Care Med 6:64

    Google Scholar 

  9. Pesenti A, Latini R, Riboni A, Gattinoni L (1982) Simple estimate of the true right to left shurt (Qs/Qt) at maintenance FIO2 by sulphur hexafluoride retention. Intensive Care Med 8:283

    PubMed  Google Scholar 

  10. Petty TL (1981) Why (not) try PEEP? Crit Care Med 9:67

    PubMed  Google Scholar 

  11. Shapiro BA, Cane RD, Harrison RA, Steiner MC (1980) Changes in intrapulmonary shunting with administration of 100% oxygen. Chest 77:138

    PubMed  Google Scholar 

  12. Shinozaki M, Ueko O, Ueyama H, Muteki T (1981) Measurement of intrapulmonary shunt by SF6 retention rate. I Experimental study on dogs with normal lungs. Jpn J Anesthesiol 30:47

    Google Scholar 

  13. Simonneau G, Lemaire F, Harf A (1981) Evaluation chez l'home des effets hémodynamiques et respiratoires de la ventilation spontanée en pression positive expiratoire (CPAP). Ann Anesth Franç 5:415

    Google Scholar 

  14. Suter PM, Fairley BH, Schlobohm RM (1975) Shunt, lung volume and perfusion during short periods of ventilation with oxygen. Anesthesiology 43:617

    PubMed  Google Scholar 

  15. Wagner PD, Salzman HA, West JB (1974) Measurement of continuous distribution of ventilation perfusion ratios: theory. J Appl Physiol 36:588

    PubMed  Google Scholar 

  16. West JB (1977) Ventilation-perfusion relationships. Am Rev Respir. Dis 116:919

    PubMed  Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Istituto di Anestesiologia e Rianimazione, Università di Milano, Via F. Sforza 35, I-20122, Milano, Italy

    A. Pesenti, A. Riboni, R. Marcolin & L. Gattinoni

Authors
  1. A. Pesenti
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. A. Riboni
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. R. Marcolin
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. L. Gattinoni
    View author publications

    You can also search for this author in PubMed Google Scholar

Additional information

Supported in part by MPI (Rome) grant CAP 18 Art. 1 Ist. 082, FC (1979/80) and CNR (Rome), contract 80.00313.86

Rights and permissions

Reprints and permissions

About this article

Cite this article

Pesenti, A., Riboni, A., Marcolin, R. et al. Venous admixture (Qva/Q) and true shunt (Qs/Qt) in ARF patients: Effects of PEEP at constant FIO2 . Intensive Care Med 9, 307–311 (1983). https://doi.org/10.1007/BF01692548

Download citation

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1007/BF01692548

Key words

Search

Navigation