Sleep and heart failure.

"For several days his breathing was irregular; it would entirely cease for a quarter of a minute, then it would become perceptible, though very low, then by degrees it became heaving and quick, and then it would gradually cease again: this revolution in the state of his breathing occupied about a minute, during which there were about thirty acts of respiration" CHEYNE, 1818 [1). Despite the over 150 yrs since its description in a patient with heart failure, Cheyne-Stokes respiration (CSR) remains something of a physiological and medical enigma. Although there have been hundreds of articles written about Cheyne-Stokes respiration, including many models of respiratory control, it is probably fair to state that we currently do not understand precisely what mechanisms initiate Cheyne-Stokes respiration, what mechanisms perpetuate the oscillation in the breathing pattern or what mechanisms terminate the oscillation. In addition, there is surprisingly little known about whether the breathing pattern itself may have an impact on the patient with congestive heart failure. In contrast to the large quantity of literature about the effect of obstructive apnoea on sleep structure and cardiorespiratory physiology, there is a paucity of information about the effect of CSR on these variables in the sleeping heart failure patient. For example, the most widely cited article on Cheyne-Stokes respiration with 186 references does not even mention sleep [2]. Two features are known by every student of medicine to be classic in heart failure; Cheyne-Stokes respiration, and paroxysmal nocturnal dyspnoea. However, very little has been written linking the two. HARRJsoN et al. [3] in 1934, in a classic work, reported that periodic breathing was present in all congestive hear failure (CHF) patients with dyspnoea on sleep onset. They also reported that the breathing pattern could be normal when the patient was awake and became abnormal "at the moment of sleep". After Cheyne-Stokes respiration started "following a long period of apnoea the subject would awaken as breathing set in"; some of the awakenings seemed to occur during the hyperpnoeic phase of CSR. HARRJsoN et al. [3] pointed out that such patients "may live for days and never sleep more than a few minutes or seconds at a time" and, not surprisingly, were described as being exhausted. All this was published three years before the frrst use of the electroencephalograph (EEG) to classify sleep [4].