Cheney has asked his former patients to buy a pulse oximeter in order record their oxygen saturation levels throughout the night while they are asleep. I don't feel like going into too much background, but he was finding from these pulse oximeter recordings that most CFS patients have multiple protracted periods of oxygen desaturation, sometimes severe (<60%), while asleep. A minute or two after these oxygen desaturation episodes begin, his patients' pulse rates spike, sometimes to very high levels.
His thesis is that the spike in pulse rate is caused by the release of adrenaline (or more generally a sharp sudden rise in sympathetic tone) that is a physiological attempt to raise oxygen flow to the brain. As this autonomic response occurs, the adrenaline release disrupts deep sleep. Hence, sleep quality is terrible and CFS patients wake up feeling unrefreshed/awful.
He is recommending low-dose oxygen at night, at most about 1 liter per minute, through an oxygen concentrator. Some patients say they are sleeping better than before and experiencing functional/clinical improvement starting about a month after beginning on PM oxygen. The amount of oxygen depends on the pulse oximetry report.
Not all CFS patients have this problem as severely as others. That is why the pulse oximeter is important. In other words, don't run out and try to buy or rent a concentrator unless you have an abnormal oximetry report. In any case, you can't buy an oxygen concentrator without a prescription.
Other CFS doctors, including KDM, have used supplemental oxygen in their practices. However, Cheney and KDM believe excessive oxygen is bad for you because it can increase oxidation. If the nighttime pulse oximetry report is normal, the supplemental oxygen is contraindicated.
He is not recommending the Nano-Vi at this time. He mentioned it at one point as a possible future treatment, but then bailed on it when one patient's echocardiography showed a slight decline in heart function after using the Nano-Vi machine. He noted that a few patients responded well to Nano-Vi when he tested how their heart function changed while on it. A few patients said it made them feel well again -- as in, cured. But this was not the case with everyone, so Nano-Vi is not part of his protocol,