[Phrenic nerve conduction of obstructive sleep apnea-hypopnea syndrome patients].

OBJECTIVE

To investigate the significance of phrenic nerve conduction time (PNCT) and diaphragm compound muscle action potential (CMAP) detection in the assessment of severity and response to treatment in obstructive sleep apnea-hypopnea syndrome (OSAHS) patients.

METHODS

Sixteen healthy volunteers (control group), 8 primary snorers (snorer group), 14 mild-moderate OSAHS patients (mild-moderate group) and 18 severe OSAHS patients (severe group) were recruited for the study from January to July in 2005. Multi-pair esophageal electrodes were used to measure PNCT and CMAP of diaphragm in response to unilateral magnetic stimulation. The study was repeated in 5 OSAHS patients after effective nCPAP treatment for at least 2 months.

RESULTS

The PNCT in severe OSAHS group was (8.9 +/- 1.2), (7.9 +/- 1.5) ms respectively, which was significantly longer than those in the control group (6.5 +/- 0.7), (6.0 +/- 0.5) ms, snorer group (6.5 +/- 1.2), (6.0 +/- 0.8) ms and mild-moderate group (7.3 +/- 1.0), (6.3 +/- 0.7) ms. The amplitude of diaphragm CMAP was (1.4 +/- 0.4), (1.4 +/- 0.3) mV in mild-moderate group and (0.9 +/- 0.4), (1.1 +/- 0.6) mV in severe group, which was significantly lower than those in the control group (2.3 +/- 0.9), (2.1 +/- 0.9) mV and snorer group (1.9 +/- 0.5), (2.1 +/- 0.7) mV, and severe patients have significantly lower CMAP than mild-moderate patients. The PNCT and CMAP of both sides for all subjects correlated significantly with oxygen desaturation index and apnea-hypopnea index. The PNCT shortened significantly after effective nCPAP treatment, which was (8.6 +/- 0.6) ms, (7.4 +/- 0.5) ms for left side and (7.8 +/- 0.6) ms, (6.5 +/- 0.5) ms for right side.

CONCLUSION

PNCT and CMAP detection with multi-pair esophageal electrodes in response to unilateral magnetic stimulation may be useful for the severity assessment and evaluation of response to effective treatment in OSAHS patients.