The Nexus ANS+ uses the galvanic skin response method which is based on the induced sudomotor axon reflex stimulations of the cholinergic sympathetic system using:

1. Direct Current at a constant voltage
2. Metaboreflex following the inflation of the ankle cuffs

It provides quantitative evaluation of the sweat response measured on disposable electrodes.

Nexus ANS+ uses Photoplethysmography (PTG) analysis derived from the pulse oximeter. PTG is an optical measurement technique using red and infrared light to measure peripheral blood volume changes.  PTG uses the time domain and spectral analysis of the waveform recording during 2 minutes of the test to retrieve information regarding artery (capillaries) stiffness, and Heart Rate Variability (HRV) Analysis.

After a Baseline ANS Evaluation is completed by assessing the Heart Rate Variability (HRV) analysis, the Cardiac Autonomic Reflex Tests (CARTs) are performed. CARTs consist of 3 tests to assess the autonomic functions of the Sympathetic and Parasympathetic Systems. The tests are as follows:

1. Valsalva Maneuver – patient bears down and attempts to exhale with mouth and nostrils closed
2. Deep Breathing – patient performs a deep breathing exercise
3. Change in Posture – patient stands up from a seated position

The Ankle-Brachial Index (ABI) is the ratio of the blood pressure at the ankle to the blood pressure in the upper arm. Compared to the arm, lower blood pressure in the leg is an indication of blocked arteries due to arterial disease. The ABI is calculated by dividing the systolic blood pressure at the ankle by the systolic blood pressure in the arm.