Reliant® from Israel-based Cheetah Medical, Inc. has been approved by the FDA, according to a report at Globes and a press release. The device promises the accuracy of measurements of cardiac output equal or better to traditional Swan-Ganz catheter. The device functions via a proprietary NICOM® technology, that is based on a traditional bioimpedance analysis (changes in voltage of electrical currents traversing the patient’s chest), plus BIOREACTANCE® technology, an analysis of frequency related effects:
The NICOM® ICU (Intensive Care Unit) and CCU (Critical Care Unit) is a non-invasive Cardiac Output monitor based on Haemodynamic Reactance Mapping, intended for the measurement and display of Cardiac Output and ECG (electrocardiogram), both at rest and under medical tests.
In ICU, non-invasive Cardiac Output monitoring by the NICOM® provides haemodynamic information, which assists in diagnosis and therapy of heart patients by establishing the patient’s baseline haemodynamic status for optimization of drug titration. The NICOM® contributes to the reduction of procedures involved with invasive PAC (Pulmonary Artery Catheter) by replacing it whenever the non-invasive NICOM® product can be utilized and also by enabling earlier removal of PAC.
The NICOM® approach incorporates a novel front end concept together with a unique electrode concept, placed on upper and lower positions of the thorax.
The NICOM® system allows superior accuracy of better than ± 5% as found in preclinical study versus Cardio Pulmonary Bypass Pump. It should be noted that the acceptable bias limit for the Swan-Ganz in the medical community is ± 20%.
A low-level electrical current is emitted and received by adjacent electrodes, while the response to the current flow produces the Haemodynamic Reactance waveform.
The previously used bioimpedance based methods for CO measurement have been based solely on analysis of the relationship between transthoracic voltage and current (impedance) measured between electrodes placed on the patients’ chest wall. To overcome these limitations, Cheetah has developed a new approach based on BIOREACTANCE® Technology, which increases signal to noise ratio by ~100 fold.
CO monitoring by the Cheetah NICOM® system uses four pairs of double electrode stickers; with the first two pairs on either side of the thorax at the level just below the sternum or ribs and the second two pairs just below the shoulders on two sides of the mid axial line. In each pair, the upper electrode delivers a small alternating current of that is sensed for its propagation characteristics along the thorax by the lower electrodes pairs, thus BIOREACTANCE® Technology is measured and a NICOM® signal is generated.
The signal is based on a number of signal descriptors, including bioimpedance. However, the main improvement of BIOREACTANCE® over bioimpedance is the relationship Cheetah has discovered and harnessed between the amount of thoracic fluid at any given point in time and frequency shifts which take place as an electric current traverses the thorax. These shifts in frequency, with the abundant information they offer are captured in the NICOM® signal which is then analyzed by the NICOM® software and presented on the NICOM® screen.
A second key innovation supporting NICOM’s performance are unique signal processing techniques based on auto-correlation, which increase the signal to noise ratio significantly compared to standard bioimpedance measurements. Thus, NICOM® is accurate also in the face of patient movement and different body types, as well as in the presence of “noise” typically found in ICU, OR and other hospital settings.
As validation of NICOM®’s robust technology the Cheetah NICOM® was directly compared in prospective studies to Swan Ganz PAC. These studies were carried out in more than 500 patients in several ICU’s in France and the US. The diverse patient population included unstable patients in general, cardiac, and post-surgical intensive care settings. Tests were conducted over time intervals that ranged from 6 to 24 hours of continuous monitoring for the obtained instantaneous cardiac output for each minute. Comparison between the two sets of results demonstrated that the NICOM® is an accurate, precise and responsive tool for totally non invasive CO monitoring, with excellent ability to detect significant CO change.
