The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts

IMPROVED PULSEOXIMETER SATURATION MONITORING DURING SIMULATED LOW PERFUSION CONDITIONS

Kelly JagerRRT, Charles Porges, Paul Mannheimer MS, Nellcor, Pleasanton, CA

BACKGROUND: Pulseoximetry technology has continued to improve over the years due in part to betterhardware and software signal processing. This has enabled the user to expandthe patient population that can be reliably monitored. One of the most difficultconditions for pulse oximetry technology is to accurately monitor patients witha weak pulse (typical during ?low perfusion?) which is often exacerbated whenthe oxygen saturation (SpO2) is also low. The purpose of this studywas to determine the lowest simulated pulse amplitude at which three differentgenerations of pulse oximeters could accurately read SpO2 and pulserate (PR) and thus compare the progress in technology.

METHOD: A computer-controlledSpO2 and PR simulator (Bio-Tek, Index 2) was used to simulate SpO2of 98% and 70% while the PR was kept constant at 90 bpm. The signal strengthwas then diminished until SpO2 or PR was either not reported within25 seconds or inaccurate by > 2% saturation points or >2 bpm. Three instruments of each model were used for each test. A paired t-testwas used to determine statistical significance. A p value of < 0.05 was consideredsignificant.

Results: Results are shownin Table 1.

Table 1

?Generation?Pulse OximeterModelLowest Mean %Signal Strength Obtained at SpO2 Value
98% SpO270% SpO2
2ndN-2000.160.16
3rdN-3000*0.06*0.14
4thN-395#0.03#0.03

*p < 0.05 compared to the N-200,# p < 0.05 compared to the N-3000 and N-200

CONCLUSION: Therehas been a five-fold improvement in the ability of new generation pulse oximeters(N-395) to acquire and accurately read the set SpO2 and PR valuesduring simulated low signal strength conditions when compared to early generation(N-200) pulse oximeters. Further studies are necessary to determine the clinicalrelevance for patients with low levels of perfusion.

OF-01-217

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