How does the interpreting sleep doctor determine which CPAP pressure to recommend?
When we initiate CPAP during a polysomnogram (PSG), we raise CPAP pressure to eliminate apneas, hypopneas, desaturations, and snoring. The lowest pressure that eliminates all these events is the pressure we recommend for home CPAP. At too low a pressure, snoring or sleep-disordered breathing may persist; at too high a pressure, patients may tolerate CPAP less well, and central apneas may appear. Because tested pressures range from a low of about 4 cm H2O to a high of about 20 cm H2O, with many steps in between, the patient may sleep only a short time at each of a number of pressures, and the interpreting physician then may recommend a pressure that was effective at relieving sleep apnea when the patient was sleeping supine, during REM, when sleep disordered breathing is expected to be worst for many patients. Depending on clinical factors during treatment, the treating physician may adjust the CPAP pressure higher or lower than was originally recommended.
