Comparison of Forehead Pulse Oximetry Sensors versus Toe Clip Pulse Oximetry
Sensors in Detecting Oxygen Saturation and Pulse Rate in Pediatric Patients in the
PACU
David M. Skolnick, D.O., Patricia W. Linhardt, M.D., Eric S. Price, D.O., Jennifer J. Pollan, Ph.D., Annie Harvey, Ph.D.
Department of Anesthesiology, University of Kansas School of Medicine-Wichita, Wichita, Kansas 67214

Introduction:
Pediatric patients are often difficult to monitor during the initial phases of recovery because they tend to be restless and uncooperative. Oxygen saturation monitoring is a critical element upon Post-Anesthesia Care Unit (PACU) arrival. Forehead pulse oximetry sensors may be safer and more reliable with pediatric PACU patients than finger/toe pulse oximetry sensors. New pulse oximetry technologies have been shown to be more resistant to motion artifact and hypoperfusion secondary to vasoconstriction.1 Forehead sensors have also been shown to detect hypoxemia faster than the traditional finger or ear clip sensors.2
Ultimately, the forehead sensor in combination with the advancing oximetry technology may decrease the length of time spent in the PACU, the number of PACU personnel required to monitor each patient, and adverse outcomes secondary to delays in recognition of hypoxemic events. Thus, the primary goal of this study was to determine if with the new technology, the forehead pulse oximetry sensor detected PACU pediatric patients’ oxygen saturation and pulse rate more reliably and quickly than the toe clip sensor, especially during periods of patient excitement and agitation.
Methods:
Following Institutional Review Board approval, the study was performed at the Wichita Clinic Day Surgery, an ambulatory surgery unit in Wichita, Kansas. Pediatric patients (ages 1 – 12 years) being operated on were studied. Immediately after undergoing their surgical procedure under general anesthesia, patients were transferred to the PACU. Monitors used included the Datascope Passport 5E (Datascope Corp., Paramus, NJ) with toe/finger clip sensors for standard pulse oximetry, the Nellcor N-595 with MaxFast forehead adhesive sensors (Nellcor Puritan Bennett, Inc., Pleasanton, CA) for forehead pulse oximetry, standard cuffs for blood pressure, and ECG sensors. Upon patient arrival in the PACU, the
anesthetist applied the MaxFast sensor to the patient’s forehead and started a stopwatch while monitoring the Nellcor pulse oximetry waveform and ECG. Simultaneously, a nurse placed the toe probe on the patient and started a stopwatch while monitoring the Passport pulse oximetry waveform and ECG. An accurate pulse oximetry reading was based on waveform, clinical correlation, and ECG pulse rate, and was defined as the point at which an acceptable pulse oximetry waveform was obtained and the pulse oximetry and ECG pulse rates were similar. Oxygen saturation was recorded when either the toe clip sensor or the
forehead sensor approximated the ECG value. When signal acquisition of the pulse oximetry reading was obtained, the respective researcher stopped the stopwatch and recorded the time to first accurate reading.
No treatment decisions were made based on forehead sensor readings.
Results:
Twenty-one children were studied with informed parental consent. Patient age ranged from 1 – 12 years (mean = 5.3, standard deviation [SD] = 3.1. Weight ranged from 11 – 71 kg (mean = 24, SD = 13). Patient temperature ranged between 94.7 – 99.0 degrees Fahrenheit (mean = 97.0, SD = 0.8). Procedure duration ranged between 3 – 67 minutes (mean = 24, SD = 19). ASA physical status classification was I (9 patients) or II (11 patients). The mean time of the first accurate oxygen saturation reading was 25 seconds (SD = 22) for the toe clip sensor and 46 seconds (SD = 53) for the forehead sensor. The pulse oximetry reading was obtained more rapidly (Sign test p < .05) with the toe probe which was faster in 16 of the 21 children. Reliability was somewhat greater for the forehead probe, based on its correlation with heart rate as determined by the EKG: Pearson’s r was .91 for the forehead and .85 for the toe probe. In the majority of cases the probe needed only a single application: 15/20 times with forehead probes and 16/20 times with toe probes. There was no difference between probes in the number of adjustments required once applied. Continuity of monitoring during Phase I recovery was achieved 91% and 76% of the time with the toe clip and forehead sensors, respectively. An accurate SpO2 reading required an average of 1.7 (SD = 1.2) personnel to obtain using the toe clip and 2.0 (SD = 1.1) using the forehead sensor.
Discussion:
In this study the forehead sensor detected pediatric patients’ oxygen saturation more slowly than the toe clip sensor did. The forehead sensor did not require more applications than the toe clip sensor did in order to obtain reliable oxygen saturation readings. Finally, the forehead sensor did not require more adjustments during Phase I recovery than the toe clip sensor did. There was concern that forehead sensors can become entangled around the head and torso of agitated pediatric patients immediately postoperatively. The
development of wireless forehead sensors could be ideal in this situation.
References:
1. Bebout DE, Mannheimer PD. Site dependent differences in time to detect changes in saturation during low perfusion. Crit. Care Med. 2001; 29(12):A115.
2. Hamber EA. Delays in the detection of hypoxemia due to site of pulse oximetry probe placement. J. Clin. Anesth. 1999; 11:113-118.

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