Comparative Study of Spo2 in all the Fingers of the Hands Measured by Pulse Oximeter

Abstract

Peripheral capillary oxygen saturation (SpO2) measured by pulse oximeter is a simple and reliable objective measurement in routine medical practice that approximates the level of oxygen in arterial blood. Measurements with this inexpensive and non-invasive method also provide heart rate and an indication of tissue perfusion. Low perfusion (due to hypothermia, low cardiac output, profound anemia, etc.), venous pulsations in a dependent limb, excessive ambient light or motion can cause pulse oximetry artifact. Carboxyhemoglobinemia, methemoglobinemia and intravenous dyes can cause false SpO2 readings. There is no information in the current literature about which finger gives the highest or reliable recording of SpO2, hence this study was taken up. Material: This is an observational study conducted among 518 patients with no co morbid conditions at our hospital. FDA approved pulse oximeter was used to estimate the SpO2. After obtaining informed consent, individuals from outpatient department of medicine aged above 18years were included in this. Subjects who were smokers, pregnant, menstruating, having ulnar or radial arterial failure due to Allen test results, hypotension, bradycardia, anemia or hemoglobinopathy, nail polish in the fingers, were excluded from the study. They were monitored after 5 min of resting. All SpO2 measurements were done in the same place and ambient light and the same brand monitor was used in all volunteers. All SpO2 values were recorded in the sitting position and simultaneous blood pressure, heart rate and body temperature were noted. Measurements of each finger were recorded after waiting at least 1 min. Observation: A total of 5180 SpO2 measurements obtained from 518 individuals. The highest average SpO2 value was measured from right middle finger (97.7% ± 1.2) and it was statistically significant. The right little finger had the lowest average SpO2 value Conclusion: Our study showed there is a difference of SpO2 between the fingers and the results were statistically significant. Hence this observation helps to accurately measure SpO2 and decreases redundancy especially in a pandemic where SpO2 value and pulse oximeter is used by large frequently.