FIG. 5:  CSA presents in different pathological patterns.^[1]  These include Cheyne-Stokes respiration (CSR), for example, which is probably the best characterized of these patterns and is most commonly observed in heart failure and some neurologic disorders.  There is also periodic breathing, Biot’s breathing, ataxic breathing, apneustic breathing, and cluster breathing, which is cyclical CSA without the CSR pattern.  There is marked variability and confusion regarding the labeling of these different breathing patterns, and the terminology is used differently in different studies. 

The next few Figures will illustrate how to define some common breathing patterns associated with Op-CSA, focusing on cluster breathing and Biot’s breathing, also known as ataxic breathing.  CSR (Figure) is characterized by gradual waxing and waning of respiratory effort, which leads to periods of hyperpnea as well as hypopneas or even frank apneas.  Respiratory cycles in CSR are generally very long.  Awakenings typically occur during the peak hyperpnea phase, and this delayed oxygen desaturation seen on polysomnography is due to the long circulatory time in cases of, for example, heart failure.  This breathing pattern has been best described in patients with heart failure or neurologic disorders, but it has also been characterized in cases of chronic opioid use.