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The last 20 years have seen remarkable gains in our understanding of the pathophysiology of sleep-disordered breathing. The rapid growth in both scientific and clinical knowledge has been fueled by the development of nonsurgical therapies for obstructive sleep apnea (OSA). These medical therapies have provided the avenue for public acceptance of the diagnosis and treatment of this common medical condition. However, medical therapy requires active patient participation, to achieve the desired outcomes of improved sleep continuity, daytime functioning, and quality of life. Conservative therapies, such as weight loss and patient positioning; and pharmacological therapies, have been disappointing. Positive pressure therapy has become the treatment of choice for the vast majority of OSA patients. Oral appliances offer an acceptable treatment alternative for select patients. Present research indicates that these mechanical approaches can produce significant decreases in the frequency and severity of sleep-disordered breathing and nocturnal oxyhemoglobin desaturation. Preliminary data from ongoing studies suggest that these interventions will reduce long-term morbidity and possibly mortality.

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PURPOSE: This study compares craniofacial measurements of lateral cephalometric radiographs of young obstructive sleep apnea patients with those of nonapneic snorers and controls. PATIENTS AND METHODS: Forty-eight patients (BM=28.0+/-3.8) with obstructive sleep apnea, 25 patients (BMI=26.3+/-3.5) with nonapneic snoring, and 54 controls (BMI=24.8+/-2.7) were evaluated. All subjects were between 18 and 40 years of age. Nineteen lateral cephalometric measurements were performed by a single investigator blinded to the results of the polysomnograms. RESULTS: Univariate logistic regression analysis of the 19 variables showed significantly increased midfacial height (ANS-N), narrowed middle airway space (MAS), steep mandibular plane angle (FMA), elongated pharynx (PNS-Eb), and inferiorly positioned hyoid bone (PNS-H, MP-H) in the obstructive sleep apnea group. The nonapneic snoring group showed only a tendency toward maxillary and mandibular retrognathia (SNA and SNB). No significant differences were found for cranial base angle (S-N-Ba), PAS, inferior airway space, maxillary unit length (ANS-PNS) mandibular unit length (Cd-Gn), tongue height (Tng-Ht), soft palate length (PNS-P), and palatal vault height (Ocl-Pal 6). The OSA group was also found to have multiple sites of abnormality of both the upper and lower pharynx, with 58% of the patients having two or more abnormal values (1 standard deviation from the mean) as opposed to 40% of the nonapneic snoring group. CONCLUSIONS: Highly significant craniofacial abnormalities were found in the upper and lower pharynx in young obstructive sleep apnea patients. Most of these patients (58%) had abnormalities in both the upper and lower pharynx, suggesting that palatal surgery alone may be an inadequate treatment. This information may define future investigations needed to determine how to more effectively treat this subgroup of young obstructive sleep apnea patients.

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Positive airway pressure in the treatment of obstructive sleep-disordered breathing (OSDB) is reviewed. Continuous positive airway pressure (CPAP), bilevel positive airway pressure, and variable (auto-CPAP) pressure, their mechanisms of action, benefits, and complications are examined. A perspective on the future of positive airway pressure therapy for OSDB is provided.

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We examined the effect of split-night polysomnography on compliance with positive pressure via a mask for the treatment of obstructive sleep-disordered breathing. A comparison of objective compliance (hours/day) at the first meter read from the positive-pressure device (4-6 weeks after set-up) in patients who had a successful split-night positive-pressure titration vs. patients who had traditional full-night positive-pressure titration was performed. Patients were matched for age, sex, and severity of the obstructive sleep-disordered breathing. Twelve patients were matched with controls who underwent full-night polysomnography. There were no significant differences between the split-night patients and the full-night patients with regard to age, sex, body mass index, and pretreatment Epworth Sleepiness Score. In addition, there was no significant difference between apnea-hypopnea index and the desaturation-event frequency for both groups pre- and post-treatment. The average daily use of continuous positive airway pressure (CPAP) at the time of the first meter reading in the group that underwent full-night positive-pressure titrations as opposed to split-night titrations was 5.2 hours/day +/- 2.2 vs. 3.8 hours/day +/- 2.9, respectively (p = 0.29). The Epworth Sleepiness Scale on the initial clinic visit (as an index of patient-perceived impairment) did not predict compliance at 4-6 weeks. The time at the final positive pressure did not correlate with compliance. Acceptance of positive pressure in the split-night patients ranged from 62 to 67%.

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PURPOSE: In the evaluation of the upper airway in patients with sleep apnea it has been suggested that cephalometric radiographs be performed at either end-inspiration or end-expiration during quiet tidal breathing. This study sought to determine if standard soft tissue cephalometric measurements vary significantly with tidal breathing. PATIENTS AND METHODS: In this prospective, controlled study 22 adult male patients with the sleep apnea/hypopnea syndrome and 27 nonapneic, nonsnoring male controls had cephalometric radiographs performed at end-tidal inspiration and end-tidal expiration. The measurements obtained from each radiograph included the posterior airway space distance, the mandibular plane to hyoid distance, and the posterior nasal spine to tip of palate (PNS-P) distance. RESULTS: There were no statistically significant differences between the inspiratory and expiratory measurements in either group. Only the PNS-P distance differed significantly between the two groups. Changes in cephalometric measurements did not occur uniformly in any one direction with tidal breathing. CONCLUSION: The data indicate that coordinating radiographic exposure to respiratory cycle phase is not necessary for soft-tissue measurements commonly used to assess upper airway patency in patients with the sleep apnea/hypopnea syndrome.

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Adenotonsillar hypertrophy has been identified as an early manifestation of human immunodeficiency virus (HIV) disease. Three patients with HIV disease were identified with obstructive sleep apnea (OSA) due to adenotonsillar hypertrophy. In order to examine the relationship between HIV-induced adenotonsillar hypertrophy and OSA, 134 patients with asymptomatic HIV disease were screened with a self-administered sleep survey designed to detect OSA and excessive daytime somnolence. Patients meeting trigger score criteria were studied with overnight polysomnography and nine additional patients were identified with OSA. The only consistent risk factor for OSA in this young and primarily nonobese population was the presence of adenotonsillar hypertrophy, found in 11 of 12 patients with OSA. Three patients had tonsillar biopsy or tonsillectomy and all displayed benign follicular lymphoid hyperplasia. Scores on the Epworth Sleepiness Scale (ESS) were significantly higher for patients with OSA, indicating a greater degree of hypersomnolence (mean ESS scores: OSA+ = 11.4 +/- 3.6, OSA- = 7.8 +/- 4.6, p = 0.012). In our population, patients with HIV disease had a prevalence of OSA of 7%. HIV-induced adenotonsillar hypertrophy is a risk factor for the development of OSA. HIV patients with complaints of excessive daytime sleepiness and snoring who are found to have adenotonsillar hypertrophy on exam should undergo a sleep evaluation to rule out the presence of OSA.

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The histopathologic diagnosis of sarcoidosis requires the presence of noncaseating granulomas. Transbronchoscopic lung biopsy (TBLB) has been considered the procedure of choice when less invasive tissue samples are unavailable. A total of 51 consecutive patients suspected of having sarcoidosis underwent combined TBLB and flexible transbronchial needle aspirate (TBNA). In 18 of the 30 patients (60 percent) with stage I disease, the diagnosis was confirmed by TBLB and 16 (53 percent) were confirmed by TBNA. The combined use of both procedures increased the diagnostic yield to 83 percent. The remaining 21 patients with stage II disease had their diagnosis confirmed in 16 (76 percent) cases by TBLB and 10 (48 percent) by TBNA with a combined diagnostic yield of 86 percent. Seven (23 percent) patients with stage I disease and 2 (10 percent) with stage II disease had their conditions diagnosed by TBNA. We conclude that combining TBNA with TBLB increases the diagnostic yield in pulmonary sarcoidosis; TBNA should complement TBLB in the diagnosis of this disease.

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STUDY OBJECTIVE: To determine the effectiveness of oronasal masks for positive pressure therapy in alleviating obstructive sleep apnea (OSA). METHODS AND PROCEDURES: Polysomnographic records of all 245 patients with OSA who underwent therapeutic trials of either continuous positive airway pressure (CPAP) or bilevel positive airway pressure between January 1991 and December 1992 were reviewed. Thirty patients who had been prescribed positive pressure therapy employing an oronasal mask were identified. Two patients known to be successfully treated with CPAP via oronasal mask underwent repeat polysomnography. The initial portion of the study was a diagnostic evaluation during which the patients were untreated. During the second portion of the study, both patients used CPAP via an oronasal mask while wearing a mouthpiece designed to maintain oral patency. RESULTS: The 30 patients with OSA who were identified in this study had significant amelioration of OSA while receiving positive pressure therapy via oronasal mask compared with the baseline, diagnostic polysomnogram (apnea index: 55.3 +/- 36.9-->1.6 +/- 3.7, p < 0.001; hypopnea index: 21.2 +/- 20-->2.7 +/- 4.9, p < 0.001; nadir of SaO2: 72.5 +/- 13.9-->87.1 +/- 4.3, p < 0.001, mean +/- SD). Improvement of OSA did not depend on maintenance of a closed mouth, as evidenced by elimination of sleep-disordered breathing in the two patients receiving positive pressure via oronasal mask while wearing a mouthpiece to keep the mouth open. CONCLUSION: Oronasal masks are a viable alternative interface for alleviating OSA with positive pressure therapy in those patients who are unwilling or unable to tolerate conventional nasal interfaces. Although there were no adverse consequences associated with the use of oronasal masks in our patients, appropriate safety precautions should be taken to minimize the possibility of aspiration of gastric contents and avoid untoward sequelae due to positive pressure device failure.

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STUDY OBJECTIVE: Although it is intuitively desirable, the measurement of arterial carbon dioxide tension (PaCO2) during diagnostic polysomnography and nocturnal trials of positive pressure therapy is invasive and potentially expensive. The accuracy of end-tidal carbon dioxide tension (PETCO2) and transcutaneous carbon dioxide (tcPCO2) monitoring in these contexts has not been systematically evaluated. This investigation was undertaken to evaluate the accuracy of PETCO2 and tcPCO2 in patients undergoing polysomnography. METHODS AND PROCEDURES: Values of PETCO2 were compared with PaCO2 in 19 patients spontaneously breathing room air (condition 1), in 13 patients receiving supplemental oxygen via nasal cannula (condition 2), and in 22 patients receiving nocturnal positive pressure ventilatory assistance (all but one with continuous positive airway pressure or bilevel positive airway pressure) (condition 3). The accuracy of tcPCO2 monitoring during sleep was also examined by comparing tcPCO2 values with simultaneously recorded PaCO2 values obtained during sleep in patients undergoing nocturnal polysomnography. Data were collected using three commercially available brands of tcPCO2 monitors (capnograph R, n = 17 patients; capnograph S, n = 17; and capnograph N, n = 15). RESULTS: Accuracy of PETCO2--There was significant scatter in the PaCO2 vs PETCO2 relationship such that only 23 percent of the variability in PaCO2 was explained by variation of PETCO2 during condition 1 and only 15 percent and 20 percent of the variability in PaCO2 was explained by variation of PETCO2 during conditions 2 and 3, respectively. 21.3 percent of patients had average PETCO2 values in error by > 10 mm Hg during condition 1, while during conditions 2 and 3, 46.2 and 63.7 percent of patients had average values in error by > 10 mm Hg, respectively. Accuracy of tcPCO2--While capnographs S and N generally overestimated PaCO2 with a wide scatter, capnograph R tended to have offsetting overestimations and underestimations of PaCO2 with a wide scatter. With each capnograph, a relatively small portion of the variability of the PaCO2 was explained by variability of the tcPCO2 (r2 = 0.2, 0.45 and 0.64 for capnographs S, N, and R, respectively). Across the three capnographs, 43.1 to 66.7 percent of measurements were in error by > 10 mm Hg, and 5 to 20 percent of measurements reflected errors > 20 mm Hg. There was no consistent relationship between the tcPCO2 error and the level of PaCO2, nor was the tcPCO2 error consistent in individual patients. There was no relationship between tcPCO2 accuracy and body mass index. CONCLUSION: Neither PETCO2, measured within a face mask, nor tcPCO2 is a consistently accurate reflection of PaCO2. This limits the utility of these variables in monitoring patients during diagnostic and therapeutic sleep studies, and in particular, during trials of nocturnal ventilatory assistance where adequate levels of support are to be established and unacceptable hyperventilation and respiratory alkalosis must be recognized.

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Snoring has been associated with an increased risk of vascular morbidity and mortality and with the complaint of excessive daytime sleepiness. Much of this risk may be attributable to concomitant sleep apnea or hypopnea. Recent work suggests that in certain individuals, snoring without apnea or hypopnea can lead to sleep disruption. This appears to be due to augmented ventilatory effort in response to an increased "internal" resistive load that results in repetitive arousals from sleep. This condition has been termed the upper airway resistance syndrome (UARS). Identification of load-related arousals in patients with the UARS may require the addition of esophageal pressure monitoring to the diagnostic polysomnogram. Nasal continuous positive airway pressure (CPAP) effectively eliminates snoring, hypopnea and apnea and therefore may be useful in treating this form of sleep-disordered breathing. The diagnostic criteria and indications, if any, for chronic treatment of these nonapneic snorers with nasal CPAP as well as long term compliance remain to be determined.

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Transbronchial needle aspiration (TBNA) offers the unique opportunity to pathologically stage patients with lung cancer at the time of diagnostic bronchoscopy. The purpose of this study was to compare the staging sensitivities of the Wang 22-gauge and 19-gauge needles. We studied 64 patients with bronchogenic carcinoma and mediastinal adenopathy. Before bronchoscopy each patient underwent chest CT. Three to four aspirates were obtained with each needle from endotracheal sites adjacent to paratracheal lymphadenopathy. In 47 patients malignant mediastinal adenopathy was confirmed by the 19-gauge needle. A total of 29 patients had malignant 22-gauge needle aspirates. Of the 64 patients, 9 had benign, reactive mediastinal lymph nodes. There were 20 patients in whom only the 19-gauge needle demonstrated malignancy and 2 patients with malignant 22-gauge needle aspirates as the sole identifier of paratracheal malignancy. As a staging tool, the 19-gauge needle was significantly more sensitive than the 22-gauge needle, 85.5 versus 52.7% (p = 0.0001). Overall, in 49 of 55 patients (89.1%) with malignant mediastinal lymphadenopathy paratracheal tumor was confirmed by TBNA. The 19-gauge TBNA staging of the mediastinum is an effective, safe, and cost-saving alternative to surgical mediastinal exploration that can be performed during initial diagnostic bronchoscopy.

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The pulmonary system may be significantly affected by hypothermia. The association between NCPE and hypothermia is controversial. A 59-year-old man with mild hypothermia presented with NCPE after passive external rewarming following accidental immersion in water. The patient's course was uneventful after 48 h, allowing immediate withdrawal of assisted ventilation and supplemental oxygen.

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Aminophylline and beta-adrenergic agonists are widely used in the treatment of obstructive lung diseases. It has been suggested that combined aminophylline and beta-agonist therapy may promote the development of atrial and ventricular arrhythmias. The effects of these agents in combination on myocardial conduction and tissue refractoriness have not been documented. We evaluated the electrophysiologic effects of intravenous aminophylline and inhaled metaproterenol on canine myocardium. Aminophylline produced significant decreases from baseline in the AH interval (85 +/- 6.5 [SD] to 63 +/- 4.1 ms [p less than 0.02]), Wenckebach cycle length (WCL) (226 +/- 8.7 to 182 +/- 5.8 ms [p less than 0.02]), and ventricular effective refractory period (VERP) (166 +/- 6.0 to 148 +/- 4.9 ms [p less than 0.01]). Metaproterenol produced similar results, except metaproterenol significantly decreased the atrial effective refractory period (AERP) from 152 +/- 6.6 to 130 +/- 3.2 ms (p less than 0.02), an effect not seen with aminophylline alone. Metaproterenol also produced significantly greater reductions in AH interval and WCL, as well as a greater increase in heart rate than aminophylline did. When compared with aminophylline alone, combined metaproterenol and aminophylline therapy produced significantly greater reductions in the AH interval (63 +/- 4.1 versus 48 +/- 1.2 ms for combined therapy [p less than 0.01]), HV interval (32 +/- 1.2 versus 28 +/- 2.0 ms for combined therapy [p less than 0.02]), WCL (182 +/- 5.8 versus 150 +/- 7.1 ms for combined therapy [p less than 0.02]), and VERP (148 +/- 4.9 versus 132 +/- 2.0 ms for combined therapy [p less than 0.02]). We conclude that both aminophylline and metaproterenol significantly enhance AV nodal and His-Purkinje conduction. Metaproterenol produced significant changes in both atrial and ventricular tissue refractoriness. Metaproterenol produced significantly greater changes than aminophylline alone, and inhaled metaproterenol combined with intravenous aminophylline produced greater changes in AV nodal and His-Purkinje conduction and ventricular refractoriness than did aminophylline alone in a canine model.

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Use of the Wang 18-gauge histology needle in TBNA was employed as a staging procedure in 29 patients with bronchogenic carcinoma and mediastinal adenopathy demonstrated on chest CT. Twenty patients had malignant aspirates; 12 had both histologic and cytologic specimens demonstrating malignancy; six patients had malignant histologic specimens; two had cancerous cytologic specimens as their only evidence of mediastinal disease. Of the nine negative aspirates, four were true negative at surgery. Five patients had false-negative aspirates. Overall sensitivity of the Wang 18-gauge histology needle in the mediastinal staging of patients with bronchogenic carcinoma was 80 percent. When patients with small cell carcinoma were excluded, sensitivity was 82 percent. The enhanced yield of the 18-gauge histology needle warrants its use in mediastinal staging of bronchogenic carcinoma. We conclude that all patients with bronchogenic carcinoma and mediastinal adenopathy demonstrated on chest CT accessible via TBNA should undergo histology needle aspiration as an initial staging procedure.

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Simultaneous washouts of He, N2, and SF6 were monitored during jet ventilation with tidal volumes of 50-200 ml and rates of 1-2 Hz. Gas concentrations were measured from the trachea and from a lower lobe bronchus in six baboons by mass spectrometry. Washouts using large tidal volumes approximated single exponential decays with the relative exponential rates of decay being He fastest, SF4 slowest, and N2 intermediate. Washouts using smaller tidal volumes demonstrated a two-phase exponential decay pattern. During the fast phase, the relative exponential rates of decay were He slowest, SF6 fastest, and N2 intermediate, the reverse order seen during large-volume washouts. During the slow phase, the relative exponential rates of decay were He fastest, SF4 slowest, and N2 intermediate, the same order seen during large-volume washouts. The magnitude of the first phase observed from the lower lobe bronchus was less than that observed from the trachea. These data are consistent with a serial two-compartment transport model incorporating a limitation of molecular diffusion between the peripheral and proximal compartments. The more rapid clearance of less diffusible gases from the central airways during the first phase of washout was due to slower transport from the alveoli to the central airways rather than faster transport from the central airways to the airway opening.

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High-frequency jet ventilation (HFJV) was studied in twelve deeply anesthetized, paralyzed dogs. Entrained volume and total expired volume were directly measured by integration of flow. Jet volume was computed from these measurements. Seven dogs were ventilated with a driving pressure of 10 psi at rates of 2 and 5 Hz for each of three mechanical loads: control, thoracoabdominal wrap, and histamine infusion. Both load conditions reduced total expired volume and entrained volume but had no effect on jet volume. Wrap reduced entrainment more at 2 Hz while the effect of histamine infusion was frequency independent. Control arterial blood gases demonstrated that PO2 was higher and PCO2 was lower during 2 Hz ventilation than during 5 Hz ventilation despite equivalent minute volumes. Five additional dogs were studied using control and wrap loads and an additional ventilator setting of 15 psi at 5 Hz. This group demonstrated that wrap reduces entrainment more at lower frequencies for ventilatory settings providing equivalent gas exchange. We conclude that increasing mechanical load reduces entrainment during HFJV and that this reduction is frequency dependent for restrictive loads.

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Giant fusiform basilar aneurysms (dolicho-ectatic basilar anomalies) are rare and have not previously been reported to cause embolic infarction in territory distal to the aneurysm. They most commonly present as posterior fossa mass lesions with brainstem compression and cranial neuropathies. Originally considered atherosclerotic in etiology, recent authors feel that they may represent a unique arteriopathy characterized by loss of elastin in the vessel wall. We report a case which presented solely as an occipital lobe infarction. To our knowledge, this is the first case in which a fusiform basilar aneurysm presented with an embolic infarction as its only manifestation.

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