RT interviews Dan Roth, director of oximetry marketing, and Earl Rozran, director of perinatal marketing, both from Nellcor Puritan Bennett.

Straight Talk

For 19 years, Nellcor, Pleasanton, Calif, has manufactured various versions and generations of pulse oximeters. RT spoke with Dan Roth, director of oximetry marketing, and Earl Rozran, director of perinatal marketing, about Nellcor’s newest developments in pulse oximetry, the OxiMax™ Pulse Oximetry System, which received 510(k) approval on March 8, and the OxiFirst Fetal Pulse Oximeter.

Q. What is unique about the OxiMax Pulse Oximetry System?
Roth: The OxiMax System is our fifth generation pulse oximetry technology. Previous pulse oximeters and those currently on the market act on a resistance calibration scheme. Up until today, all pulse oximeters have used one to several calibration curves programmed into the monitor to calculate oxygen saturation. That is fine, as long as your sensor designs fit one of the preprogrammed curves. In essence, it limits sensor design. With OxiMax, we have imbedded a digital memory chip within the sensor itself that contains all of the calibration and operating characteristics for that sensor design. We are no longer restricted by preprogrammed calibration curves fixed in the monitor.

OxiMax is a platform consisting of our pulse oximeter, the N-595, an OxiMax OEM board, and an array of different sensors. To build on the OxiMax platform, we launched a specialty sensor, MAX-FAST (adhesive forehead sensor). When patients have poor pulse perfusion, arterial blood traveling from the heart reaches the head much sooner than the hands. MAX-FAST displays changes in oxygen saturation typically 1 to 2 minutes earlier than digit sensors during these conditions. All other head sensors on the market today operate with an accuracy of ±3%. MAX-FAST operates with an accuracy of ±2%.

Q. What does it mean to receive the 2002 Medical Design Excellence Award (sponsored by Canon Communications) for its OxiFirst™ Fetal Pulse Oximeter and Fetal Sensor?
This award acknowledges more than a decade of pioneering research and development carried out by Nellcor to make fetal pulse oximetry available to obstetrical clinicians worldwide. The OxiFirst Fetal Pulse Oximetry System is now being used in more than 250 hospitals in the United States by clinicians who recognize the proven clinical value and added peace of mind that fetal pulse oximetry offers during labor and delivery.

Q. How is this oximeter specialized for infants?
The important clarification here is that the OxiFirst system is designed to continuously monitor intrapartum fetal oxygen saturation. The system is used as an adjunct to fetal heart rate monitoring for singleton fetuses of Ž36 weeks gestation with a nonreassuring fetal heart rate pattern.

In terms of differentiation from traditional pulse oximetry, the OxiFirst system utilizes a variation on the standard sensor types. There are two types of pulse oximetry sensors: transmission and reflectance. Both rely on the same operating principles but differ in the positioning of the optical components relative to the vascular bed. In transmission pulse oximetry, the light-emitting diodes (LEDs) and photodetector are positioned on opposite sides of a vascular bed, and light absorption across that bed is determined. This is what is typically seen with disposable sensors of this design positioned on the end of a finger.

In reflectance pulse oximetry, the LEDs and photodetector are positioned adjacent to one another on the same skin surface, and absorption is determined from light that scatters back to the tissue surface. Since the intrapartum fetus does not offer easy access to fingers to enable a clinician to place a transmission-style pulse oximetry sensor, we utilize a reflectance sensor for the OxiFirst system. The sensor rests against the fetal cheek to provide a quantitative FSpO2 value. This is a direct, objective, and real-time measurement of the percent of oxygen saturation in fetal arterial blood.