ZOE® is a noninvasive medical device that measures fluid status via bioimpedance. Two hydrogel electrodes are placed at the top and bottom of the breastbone, also known as the sternum. ZOE® measures the time it takes a low frequency current to travel between the two sensors, indicating fluid level. Fluid decreases resistance or impedance and dry environments increase electrical resistance or impedance. Consequently, the more fluid in the body, the less resistance or lower the Zo measurement, and the dryer the body the higher Zo number that is displayed on the ZOE®.

WHAT IS Zo?
Zo refers to “Z naught”, or base resistance in ohms. The symbol for electrical resistance or ohms is “Ω”. Zo has been measured for years in cardioplethsmograph technology such as the IQ Noninvasive Hemodynamic Monitor. Normal Zo in human subjects has been determined to range from 19-30 ohms. Less than 19 ohms indicates that the subject may be overhydrated, and Zo greater than 30 indicates that the subject is becoming dehydrated.

The ZOE® provides objective data for the early intervention of heart failure, dyspnea, hypertension, and other critical events related to hemodynamic status.

* This is when home care nursing intervention must occur to prevent CHF and hospitalization.
(Frantz A. Breaking down the barriers to heart failure patient self-care. Home Healthcare Nurse Journal. 22(2): 109-115, 2004.)

THE NONINVASIVE CHEST X-RAY
In 1996, Dr. David Milzman conducted a study of 117 adults entering the emergency department with a complaint of difficulty breathing. Prior to obtaining a chest x-ray, these patients were placed on an IQ2™ cardioplethsmograph for Zo measurements of 17 ohms. Patients' x-rays showing pulmonary edema had Zo measures of 15 ohms or less. The results of this study caused Dr. Milzman to name Zo measurement the "noninvasive chest x-rays." Zo measurement is a quick eaasy method for determining amount of pulmonary congestion.

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