@2024 Afarand., IRAN

---

ISSN: 2252-0805    The Horizon of Medical Sciences 2017;23(2):105-109

Background
… [1-9]. Today, in the intensive care unit, in order to continuous monitoring of oxygen saturation, finger and ear pulse oximetry is used [10-14]. The reason for choosing the upper earpiece for finger pulse oximetry is also the frequent use of this section to connect finger pulse oximeter sensor in bed by colleagues.
Previous Studies
The study of Jeffrey which was performed on outpatients who had referred for pulmonary function tests, showed that pulse oximeter of the ear with a finger sensor cannot provide us with precise results of oxygen saturation [15].
Aim(s)
The aim of this study was to determine the precision of ear and tip finger pulse oximetry in mechanically ventilated ICU patients.
Research type
This is a comparative-analytic study.
Research society, place and time
This study was carried out in 2015 in the intensive care unit of Kashmar City Modarres Hospital.
Sampling method and number
60 patients were selected through simple and convenience sampling method.
Used devices&materials
Of patients under the study, one milliliter arterial blood was taken in heparinized syringe. At the same time with taking arterial blood samples, two finger pulse oximeter sensors (Alborz2, Iran) which were already calibrated with each other and their accuracy were confirmed were attached to the patient`s right hand pointed finger and the other to upper part of right ear. SpO2 (Blood Oxygen Saturation Level) obtained from the sensors was read and recorded if (1) natural plethysmography waves and 2)pulse differences obtained from sensors were less than 5. However, if they did not have these two characteristics or if during their reading, the patient became worse, the patient was excluded from the study. Then, the results of SaO2 (arterial saturation) and SpO2 finger and ear were recorded in a special form. Statistical analysis:Data were analyzed using SPSS 22 software. ANOVA with repeated measure, and Spearman Correlation were used for data analysis.
Findings by Text
The number of male and female samples were equal. The mean age of the research unit was 69.83±14.84 years. Most of the samples (33) were under the SIMV mode and others were under CPAP mode. 46.7% of the samples had environmental edema (Table 1). There was a significant difference between the mean percentage of oxygen saturation of pulse oximetry of the ear, fingertip and arterial blood (p<0.001) that ear and fingertip showed the highest and lowest percentage of oxygen saturation. Also, there was a significant difference between ear, fingertip and monitoring heart rate pulse oximetry (p<0.001; Table 2). There was statistically significant relation between the percentage of oxygen saturation of ear (r=0.56), fingertip (r=0.50), and arterial blood (r=0.58) pulse oximetry with PaO2 (Partial Pressure of Oxygen) (p=0.001). However, the above items did not show significant correlation with environmental edema especially the hands (p<0.05). Also, the percentage of oxygen saturation in persons with higher PaO2 and less than 80 mmHg had significant difference; that is the oxygen saturation decreased with decreasing oxygen pressure (p<0.001; Table 3). The mean difference in percentage of oxygen saturation between fingertip and arterial blood as well as between ear and arterial blood were -1.35±3.58 and 4.26±1.84 respectively. Of the 60 cases, ear pulse oximetry in 44 cases (73%) and fingertip in 16 cases (%27) had more than 3% difference with SaO2.
Main comparison to the similar studies
In the present study, the pulse oximetry of the ear compared to the finger measured the heart rate closer to the monitor although the difference in finger heart rate pulse oximetry and monitoring was less than 2 units that can be ignored in the clinical setting and indicate that for monitoring heart rate there is no difference in using a finger pulse oximeter sensor on a finger or ear. Also, in the present study, in all cases of ear pulse oximetry, the percentage of oxygen saturation was higher than fingertip and arterial blood that two reasons may be mentioned for the higher pulse oximeter of the ear: First, the difference in the rate of absorption of the red light at 660 nm and intra-red light at 940 nm with a finger pulse oximetry when it is used in place other than its standard and anatomical positon i.e. ear, because there is a lot of difference between the depth and structure of finger and ear tissues; and, secondly, the incorrect positioning of finger pulse oximeter sensor in the ear and the creation of an optic shunt so that light travels from the emitting diode of the light to the absorbing light diode without passing through the ear tissue. … [16-21].
Suggestions
A study is recommended to investigate the precision of the ear pulse oximetry with a special sensor in the intensive care unit.
Limitations

Conclusions
Using ear pulse oximetry with finger sensor in front of the tip of the finger cannot accurately measure the oxygen saturation in patients under mechanical ventilation in ICU although the finger pulse oximetry accuracy decreases when arterial blood pressure decreases.
Acknowledgments
In the end, I am grateful to the professor Mehdi Basirimoghadam, the Graduate Council, and Research Council of the Student Research Committee of Gonabad University of Medical Sciences and all the patients participating in this study.
Conflict of interest
Non-declared
Ethical Permissions
The ethical confirmation of this study was obtained from the Ethics Committee of the Gonabad University of Medical Sciences (IR. gmu. rec. 1394.96).
Funding Sources
This article is part of the dissertation of Intensive Care Nursing Graduate Course, Nursing and Midwifery Faculty of Gonabad University of Medical Sciences.

TABLES and CHARTS

Show attach file