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LETTER TO THE EDITOR

Using Pulse Oximetry Waveform Analysis to Guide Fluid Therapy: Are We There Yet?

Department of Anesthesia and Critical Care; Béclère Hospital-University Paris XI; Clamart, France; michard.frederic{at}free.fr

To the Editor:

Many studies have shown that ventilation-related changes in arterial pressure are accurate predictors of the hemodynamic effects of fluid loading (1). Results from studies investigating the clinical value of ventilation-related changes in pulse oximetry waveform vary considerably (2–7). Importantly, studies (2,4) showing a close relationship between arterial pressure and pulse oximetry waveforms analyzed the amplitude (or "pulse") component of the arterial pressure and pulse oximetry signals, whereas studies (5,6) reporting a weak relationship considered only the peak (or "systolic") component of both signals.

In a recent study Shelley et al. (8) showed that the pulse oximetry waveform is highly dependent on the site of measurement, with respiratory variations of the waveform from the ear almost 18 times greater than those from the finger. Unfortunately, the frequency-domain methodology used (Fourier analysis) to analyze the pulse oximetry signal could not discriminate between respiratory variation in peak values and variation in amplitude values.

From the figure published by Shelley et al. we suspect that whereas the site of measurement appears to markedly influence the magnitude of changes in peak values, it does not affect significantly the magnitude of changes in amplitude (Fig. 1). However, this hypothesis remains to be confirmed before supporting the use of pulse oximetry as a tool to guide fluid therapy in patients undergoing surgery or in critically ill patients. Shelley et al. may clarify this issue by providing a simple time-domain analysis of their recordings.

View larger version (49K): [in this window] [in a new window]   Figure 1. The influence of the site of measurement is obvious on respiratory changes in peak (or "systolic") values, but not on respiratory changes in amplitude (or "pulse") values. On this example, the respiratory changes in amplitude (or "pulse") values are very small at all sites, since respiratory changes in minimum (or "diastolic") values are almost as large as changes in peak values. Adapted from Shelley et al. (8).

REFERENCES

1. Michard F. Changes in arterial pressure during mechanical ventilation. Anesthesiology 2005;103:419–28.[Web of Science][Medline]
2. Natalini G, Rosano A, Franceschetti ME, et al. Variations in arterial blood pressure and photoplethysmography during mechanical ventilation. Anesth Analg 2006; 103:1182–8.[Abstract/Free Full Text]
3. Natalini G, Rosano A, Taranto M, et al. Arterial versus plethysmographic dynamic indices to test responsiveness for testing fluid administration in hypotensive patients: a clinical study. Anesth Analg 2006;103:1478–84.[Abstract/Free Full Text]
4. Cannesson M, Besnard C, Durand PG, et al. Relation between respiratory variations in pulse oximetry plethysmographic waveform amplitude and arterial pulse pressure in ventilated patients. Crit Care 2005;9:R562–R568.[Web of Science][Medline]
5. Shamir M, Eidelman LA, Floman Y, et al. Pulse oximetry plethysmographic waveform during changes in blood volume. Br J Anaesth 1999;82:178–81.[Abstract/Free Full Text]
6. Golparvar M, Naddafnia H, Saghaei M. Evaluating the relationship between arterial blood pressure changes and indices of pulse oximetric plethysmography. Anesth Analg 2002;95:1686–90.[Abstract/Free Full Text]
7. Solus-Biguenet H, Fleyfel M, Tavernier B, et al. Non-invasive prediction of fluid responsiveness during major hepatic surgery. Br J Anaesth 2006;97:808–16.[Abstract/Free Full Text]
8. Shelley KH, Jablonka DH, Awad AA, et al. What is the best site for measuring the effect of ventilation on the pulse oximeter waveform. Anesth Analg 2006;103:372–7.[Abstract/Free Full Text]

This article has been cited by other articles:

				K. H. Shelley, D. H. Jablonka, A. A. Awad, R. G. Stout, H. Rezkanna, and D. G. Silverman Using Pulse Oximetry Waveform Analysis to Guide Fluid Therapy: Are We There Yet? Anesth. Analg., June 1, 2007; 104(6): 1607 - 1609. [Full Text] [PDF]

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Anesthesia & Analgesia® is published for the International Anesthesia Research Society® by Lippincott Williams & Wilkins with the assistance of Stanford University Libraries' HighWire Press®. Copyright 2006 by the International Anesthesia Research Society. Online ISSN: 1526-7598   Print ISSN: 0003-2999