Apnea And Hypopnea Index Research Articles

Obstructive Sleep Apnea Syndrome

The place of surgical treatment in obstructive sleep apnea syndrome (OSAS) remains unclear. Uvulopalatopharyngoplasty (UPPP) has a response rate of 41% overall and only 5% when retrolingual narrowing is present. Thus, in cases with suspected hypopharyngeal collapse maxillofacial surgery has been proposed with improved results. The Stanford group has designed a step-by-step surgical procedure tailored to the specific anatomical abnormalities encountered in each patient. The goal is to avoid a full maxillomandibular advancement osteotomy (MMO), at least in a subgroup of patients, beginning with a limited mandibular osteotomy (with or without hyoid myotomy and hyothyroidopexy and with or without UPPP) (phase 1 surgery). In this procedure MMO is performed as the second or third step (phase 2 surgery). The present study reports on our prospective experience with 51 consecutive patients (64 surgical procedures) treated by the step-by-step maxillofacial surgery previously described by the Stanford team. Only 2 of the 53 patients initially treated were lost for follow-up. Surgery was considered a success if the postoperative apnea and hypopnea index (AHI) was less than 15/h with at least a 50% reduction. Forty-four patients had phase 1 surgery. The success rate was 22.7% (10 of 44). The mean AHI was unchanged with a trend for reduction in the apnea index. Twenty patients had maxillomandibular advancement surgery (phase 2) (13 failures of phase 1, 7 patients primarily because of facioskeletal deformities). The AHI decreased from 59 +/- 29/h to 11 +/- 9/h after phase 2. Of the patients 75% (15 of 20) were considered to have had a successful outcome. In conclusion, phase 1 does not seem effective in most patients with OSAS. The results of phase 2 surgery are successful in young patients with severe OSAS even if the surgical technique is more aggressive.

Supine Cephalometric Analyses of an Adjustable Oral Appliance Used in the Treatment of Obstructive Sleep Apnea.

OBJECTIVE: To investigate the effects of the Klearway(TM) appliance on the upper airway in patients with obstructive sleep apnea (OSA) in the supine position. METHODS: Sixteen subjects (12 males and 4 females) were recruited on the basis of baseline polysomnography with a documented Apnea and Hypopnea Index (AHI) >15 per hour. A second overnight sleep study was performed for each subject with the appliance in place. Baseline supine cephalometry was performed for each subject before the initial insertion of the appliance, and follow-up supine cephalometry was undertaken with the appliance in place. RESULTS: The polysomnographic variables improved significantly, and the mean changes in overbite and overjet were 5.15 mm and 6.26 mm after insertion of the Klearway(TM) appliance. The supine sagittal cross-sectional areas of the pharynx and the tongue significantly increased, while the linear distance from the hyoid position to the mandibular plane or the RGN-C3 line significantly decreased after insertion of the appliance. The ratio of the vertical pharyngeal length to the sagittal cross-sectional area of nasopharynx or tongue decreased significantly. When the subjects were evaluated on the basis of the after-insertion AHI, the group with good response (n = 11) was found to be significantly younger than the group with the poor response (n = 5). Similarly, the good responders revealed less prominent chins, larger tongue heights, and an increase in hypopharyngeal sagittal cross-sectional area after insertion of the appliance. There was a significant correlation between the improvement in AHI (%) and the supine middle airway space (r = -0.52, p < 0.05). CONCLUSION: The mechanical effect of the Klearway(TM) appliance on the upper airway and the stabilization of jaw posture may be important determinants of the efficacy of the appliance.

Central sleep apnea after interrupting longterm acetazolamide therapy

One month administration of acetazolamide (ACET) (at sea level) improves periodic breathing and decreases the number of central apneas (CA) ( De Backer et al., 1995Am. J. Respir. Crit. Care Med. 151, 87–91) in nonhypercapnic central apnea syndrome. It remains unclear whether cessation of therapy would provoke recurrence of symptoms. In the present study we evaluated the number of CA after 1 and 6 months interruption of ACET therapy. Eight patients with central sleep apnea were included [central apnea index (CAI)>5 or apnea and hypopnea index (AHI)>10 and obstructive apnea index (OAI)<5]. Polysomnography was repeated once after 1 month treatment (N2), after 1 month off treatment (N3) and after 6 months off treatment. CAI (25±10 at N1) decreased during N2 (4±2) and N3 (5±3) and remained low after N4 (3±1). However an increase in the number of obstructive apneas and central hypopneas could be observed together with a shift from central apnea to hypopnea after N4. Maybe ACET induces a long lasting resetting of the CO 2 threshold which is still present after interruption of the therapy.

Multiple sleep latency test (MSLT) and sleep apnea in aged women.

Sleep disturbance and the tendency to sleep during the day were assessed polysomnographically in 31 elderly women (mean age = 76.7 +/- 3.6 SD) recruited from a senior citizen's living facility without reference to sleep-wake complaints. The data showed that the level of sleepiness during the day in each subject depended in part on the severity of her respiratory disturbance. It was found that the group (n = 7) of elderly females with apnea and hypopnea index (AHI) higher than 20 was more sleepy [multiple sleep latency test (MSLT) = 7.9 +/- 2) than the group (n = 10) with AHI > 5 but less than 20 (MSLT = 12.7 +/- 5). Nevertheless, the presence and severity of respiratory disturbance were not the only factors that influenced the level of sleepiness during the day in the studied sample. A subgroup of four elderly females showed a marked sleepiness during the four tested periods (MSLT = 5.2 +/- 0.6) with a very low respiratory disturbance index (AHI = 5.5 +/- 0.8).