Reproducibility of a standardized titration procedure for the initiation of continuous positive airway pressure therapy in patients with obstructive sleep apnoea.

BACKGROUND

Manual titration of continuous positive airway pressure (CPAP) under polysomnographic control is the method most commonly employed to establish the minimal effective pressure (P(eff)) for the treatment of the obstructive sleep apnoea syndrome (OSA). To date, however, the reproducibility of P(eff) titrated in this way has not been investigated in any detail.

OBJECTIVES

The present study aims to establish the reproducibility of P(eff) determined by manual titrations of CPAP under polysomnographic control in the sleep lab.

METHODS

In a group of 50 patients (5 women), with a mean (SD) apnoea-hypopnoea index of 39.3 (21.8), apnoea index of 28.1 (20.9) and oxygen desaturation index of 39.3 (22.6), with newly diagnosed OSA, manual titration of CPAP was performed on two consecutive nights using the following standard titration protocol: starting at 4 mbar, CPAP was increased by steps of 1 mbar at intervals of at least 5 min, until no signs of airway obstruction could be seen, and arousals were no longer elicited. When no airway obstruction was detected over a period of 30 min, the pressure was lowered once during the night in steps of 1 mbar at intervals of at least 10 min, until obstructive events reappeared, whereupon the pressure was again increased as described above, until, once more, no signs of airway obstruction and no arousals occurred. The second titration was carried out in a blind manner, that is the lab technician did not know the results of the first pressure titration.

RESULTS

The mean (SD) P(eff) for all titrations was 8.1 mbar (2.9). A high level of correlation was found between the P(eff) titrated on the first night and that titrated on the second night (Spearman correlation coefficient = 0.89). In a few individual cases, however, differences of up to 3 mbar were found between P(eff) on the first night and P(eff) on the second night. On average, the P(eff) measured on the second night was 0.5 mbar (SD = 1.3, range: -2.0 to 3.0 mbar) higher than that of the first night.

CONCLUSIONS

With standardization of the manual titration of CPAP, P(eff) is readily reproducible. In individual cases, however, a difference of as much as 3.0 mbar between the two titrations is possible.