Abstract
The objective of this study was to evaluate a new reflectance pulse oximeter sensor. The prototype sensor consists of 8 light-emitting diode (LED) chips (4 at 665 nm and 4 at 820 nm) and a photodiode chip mounted on a single substrate. The 4 LED chips for each wavelength are spaced at 90-degree intervals around the substrate and at an equal radial distance from the photodiode chip. An optical barrier between the photodiode and LED chips prevents a direct coupling effect between them. Near-infrared LEDs (940 nm) in the sensor warm the tissue. The microthermocouple mounted on the sensor surface measures the temperature of the skin-sensor interface and maintains it at a preset level by servoregulating the current in the 940-nm LEDs. An animal study and a clinical study were performed. In the animal study, 5 mongrel dogs (weight, 10–20 kg) were anesthetized, mechanically ventilated, and cannulated. In each animal, arterial oxygen saturation (SaO2) was measured continuously by a standard transmission oximeter probe placed on the dog's earlobe and a reflectance oximeter sensor placed on the dog's tongue. In the first phase of the experiment, signals from the reflectance sensor were recorded while the dog was immersed in ice water until its body temperature decreased to 30°C. In the second phase, the animal's body temperature was normal, and the oxygen content of the ventilator was varied to alter the SaO2. In the clinical study, 18 critically ill patients were monitored perioperatively with the prototype reflectance sensor. The first phase of the study investigated the relationship between local skin temperature and the accuracy of oximeter readings with the reflectance sensor. Each measurement was taken at a high saturation level as a function of local skin temperature. The second phase of the study compared measurements of oxygen saturation by a reflectance oximeter (SpO2[r]) with those made by a co-oximeter (SaO2[IL]) and a standard transmission oximeter (SpO2[t]). Linear regression analysis was used to determine the degree of correlation between (1) the pulse amplitude and skin temperature; (2) SpO2(r) and SaO2(IL); and (3) SpO2(t) and SaO2(IL). Student'st test was used to determine the significance of each correlation. The mean and standard deviation of the differences were also computed. In the animal study, pulse amplitude levels increased concomitantly with skin temperature (at 665 nm,r=0.9424; at 820 nm,r=0.9834;p<0.001) and SpO2(r) correlated well with SaO2(IL) (r=0.982; SEE=2.54%;p<0.001). The results of the clinical study are consistent with these findings. The proto-type reflectance pulse oximeter sensor can yield accurate measurements of oxygen saturation when applied to the forehead or cheek. It is, therefore, an effective alternative to transmission oximeters for perioperative monitoring of critically ill patients.
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Van Assendelft OF. Spectrophotometry of hemoglobin derivatives. Assen, The Netherlands: Royal Vangorcum Ltd, 1970
Challoner AVJ. Photoelectric plethysmography for estimating cutaneous blood flow. In: Rolfe P, ed. Noninvasive physiological measurements. London: Academic, 1979:125–151
Yamakoshi K, Shimazu H, Shibata M, et al. A new oscillometric method for indirect measurement of systolic and mean arterial pressure in the human finger (part 1): Model experiment. Med Biol Eng Comput 1982;20:307–313
Shimazu H, Fukuoka M, Ito H, et al. Noninvasive measurement of beat-to-beat vascular visoelastic properties in human fingers and forearms. Med Biol Eng Comput 1985;23:43–47
Aoyagi T, Kishi M, Yamaguchi K, et al. Improvement of the earpiece oximeter. 13th annual meeting Jpn Soc Med Electronics Biomed Eng 1974:90–91
Yelderman M, New W Jr. Evaluation of pulse oximetry. Anesthesiology 1983;59:349–352
Severinghaus JW, Naifeh KH. Accuracy of response of six pulse oximeters to profound hypoxia. Anesthesiology 1987;67:551–558
Pologe JA. Pulse oximetry; technical aspects of machine design. Int Anesthesiol Clin 1987;25:137–153
Mendelson Y, Cheung PW, Neuman MR, et al. Spectrophotometric investigation of pulsatile blood flow for transcutaneous reflectance oximetry. Adv Exp Med Biol 1983;159:93–102.
Mendelson Y, Kent JC, Yocum BL, et al. Design and evaluation of a new reflectance pulse oximeter sensor. Med Instrumentation 1988;22:167–173
Shimada Y, Nakashima K, Fujiwara Y, et al. Evaluation of new reflectance pulse oximeter for clinical applicability. Med Biol Eng Comput 1991;29:557–561
Cui W, Ostrander LE, Lee BY. In vivo reflectance of blood and tissue as a function of light wavelength. IEEE Trans Biomed Eng 1990;37:632–639
Merrick EB, Hayes TJ. Continuous, noninvasive measurements of arterial blood oxygen levels. Hewlett-Packard J 1976;28:2–9
Mendelson Y, McGinn MJ. Skin reflectance pulse oximetry: in vivo measurements from the forearm and calf. J Clin Monit 1991;7:7–12
Takatani S, Graham MD. Theoretical analysis of diffuse reflectance from a two-layer tissue model. IEEE Trans Biomed Eng 1979;26:656–664
Takatani S. Toward absolute reflectance oximetry: theoretical consideration for noninvasive tissue reflectance oximetry. Oxygen Transport to Tissue 1989;11:91–102
Takatani S, Noon GP, Nose Y, DeBakey ME. Design and evaluation of a reflectance oxygen sensor in critically ill patients. Oxygen Transport to Tissue XIV, 1992 (in press)
Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1:307–310
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This research was partially supported by a grant in aid from Nippon Colin Electronics, Komaki, Japan. The authors also acknowledge the Southwest Research Institute in San Antonio for assembling the prototype optical sensor reported in this paper.
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Takatani, S., Davies, C., Sakakibara, N. et al. Experimental and clinical evaluation of a noninvasive reflectance pulse oximeter sensor. J Clin Monitor Comput 8, 257–266 (1992). https://doi.org/10.1007/BF01617907
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DOI: https://doi.org/10.1007/BF01617907