Pulse Oximetry
A pulse oximtetry is a non-invasive continuous measure of arterial oxygenation using a pulse oximeter probe which is attached to a pulsating vascular bed such as the finger, ear lobe or toe (Cichero, 2006). The tool measures O2 saturation within the blood stream; it is hypothesized that oxygen saturation within the bloodstream will decrease when a patient aspirates. There is debate over whether the pulse oximeter is an appropriate measure of aspiration and some research suggests that it is a clinically irrelevant marker of aspiration although statistically significant (Leder, 2000). Others suggest that pulse oximetry is a useful tool to confirm suspicion of swallowing difficulty, but is not precise enough to indicate if the client has experienced penetration or aspiration (Cichero, 2006). It furthermore cannot tell the clinician in which stage the aspiration occurred as oxygen de-saturation can present itself up to 2 minutes post-swallow (Groher, 2010). Therefore, pulse oximetry should never be used on its own, it is however a useful adjunct to the clinical examination.


Special Considerations of Pulse Oximetry and the COPD population

A baseline mupulse_oximeter.jpgst be taken. Normal oxygen saturation levels are around 95% - 100%; readings less than 90% indicate significant problems (Cichero, 2006). As people with COPD have significantly comprised respiratory systems, the clinician should not expect the oxygen saturation levels to be within the normal range. There is considerable debate in the literature as to what decrease in saturation level signifies penetration/aspiration; Zaidi et. Al (1995) suggest that aspiration was likely to occur if saturation levels fell by 3.28%, wheras Leder (2000) suggested that patients with severe COPD exhibited a mean decrease of only 1.8% of oxygen saturation levels throughout a meal. The literature does however support the use of pulse oximetry to document respiratory function during swallowing but may not respond purely to aspiration episodes (Cichero, 2006). Therefore this tool may be particularily useful for a client with a diagnosis of COPD as it is a useful vehicle to measure swallow-respiratory abilities (op.cit). As this population has been shown to have a large amount of undetected dysphagia, the pulse oximeter may be a useful tool for the clinician to highlight those clients who have poor swallow-respiration coordination and/or fatiguability throughout the meal due to decreasing oxygen saturation. As studies have demonstrated that clinician often ‘miss’ those clients who silently aspirate (Langmore, et. al., 2006) clients who do not show any clinical indicators of aspiration but demonstrate desaturation could be referred for instrumental examinations (Sherman, Niesenboum Jeserger, 1999).


References

Cichero, J. (2006). Clinical Assessment, Cervical Ausculation and Pulse Oximetry. In J.A.Y. Cichero & B.E. Murdoch (Eds). Dysphagia: Foundation, Theory and Practice. Chichester: Wiley.

Groher, M. E. C. M. (2010). Dysphagia: Clinical Management in Adults and Children. Maryland Heights: Missouri: Mosby, Inc.

Langmore, S. E., Terpenning, M. S., Schork, A., Chen, Y., Murray, J. T., Lopatin, D., et al. (1998). Predictors of Aspiration Pneumonia: How Important Is Dysphagia? Dysphagia, 13(2), 69-81.

Leder, S. B. (2000). Use of Arterial Oxygen Saturation, Heart Rate, and Blood Pressure as Indirect Objective Physiologic Markers to Predict Aspiration. Dysphagia, 15(4), 201-205.

Sherman, B., Nisenboum, J. M., Jesberger, B. L., Morrow, C. A., & Jesberger, J. A. (1999). Assessment of Dysphagia with the Use of Pulse Oximetry. Dysphagia, 14(3), 152-156.

Zaidi, N. H., Smith, H. A., King, S. C., Park, C., O'Neill, P. A., & Connolly, M. J. (1995). Oxygen Desaturation on Swallowing as a Potential Marker of Aspiration in Acute Stroke. Age and Ageing, 24(4), 267-270.