Accidents in obstructive sleep apnea patients treated with nasal continuous positive airway pressure: a prospective study. The Working Group ANTADIR, Paris and CRESGE, Lille, France. Association Nationale de Traitement à Domicile des Insuffisants Respiratoires

Many studies have shown a relationship between obstructive sleep apnea (OSA) and accidents, but to our knowledge, none have investigated prospectively the effects of treatment with nasal continuous positive airway pressure (CPAP). CPAP was proposed to 973 patients, of whom 893 patients actually underwent CPAP. These patients were consecutively invited to enter a prospective follow-up study including a questionnaire before treatment and after 6 and 12 months of treatment; 547 patients completed the study (153 left the study, and only partial data were available for 193). The baseline questionnaire included questions concerning accidents in the previous 12 months, asking whether patients had had an accident and, if so, whether they felt that the accident(s) were related to sleepiness, and whether the patients felt that they had had near-miss accidents due to sleepiness. The questionnaires at 6 and 12 months included the same questions referring to the previous 6 months; the accidents reported on each follow-up questionnaire were cumulated and compared with the accidents during the 1-year period before treatment. The number of patients having an accident decreased with treatment for real accidents (from 60 to 36; p<0.01), as well as for near-miss accidents (from 151 to 32; p<0.01). The average number of accidents per patient also decreased, for real accidents (from 1.6+/-1.3 to 1.1+/-0.3; p<0.01) and for near-miss accidents (from 4.5+/-6.5 to 1.8+/-1.4; p<0.01). The cost, in terms of days in hospital related to accidents, decreased from 885 to 84 days. With caution due to the absence of a control group, it is suggested that treatment with CPAP decreases the number of accidents occurring in OSA patients. This result may have important implications in the evaluation of the cost/benefit ratio when treating OSA patients.

Five-year effects of nasal continuous positive airway pressure in obstructive sleep apnoea syndrome

There have been very few studies assessing the long-term physiological effects of nasal continuous positive airway pressure (CPAP) for the obstructive sleep apnoea syndrome. We therefore investigated prospectively the evolution of lung function, arterial blood gases and pulmonary haemodynamics in patients with this syndrome treated with CPAP. Sixty five patients were included. The mean duration of home treatment with nasal CPAP was 64+/-6 months. Most of the patients (77%) were smokers at the baseline assessment. We observed a small, but significant, decrease in forced expiratory volume in one second (FEV1) from 80+/-21% at baseline (t0) to 76+/-21% of the predicted value at the follow-up evaluation (t5) (p<0.01). Arterial oxygen tension (P[a,O2]) for the group as a whole remained stable (9.4+/-1.5 kPa (71+/-11 mmHg) versus 9.4+/-1.2 kPa (71+/-9 mmHg)). However, P(a,O2) increased in the subgroup of patients with hypoxaemia at t0 (n=23), from 7.8+/-0.7 kPa (59+/-5 mmHg) to 8.9+/-1.2 kPa (67+/-9 mmHg). Arterial carbon dioxide tension (P[a,CO2]) for the group as a whole increased slightly, but significantly, from 5.2+/-0.7 kPa (39+/-5 mmHg) to 5.4+/-0.5 kPa (41+/-4 mmHg) (p<0.05). Mean pulmonary artery pressure (Ppa) at rest did not change (16+/-5 mmHg versus 17+/-5 mmHg; NS) nor did exercising Ppa. In the 11 patients with pulmonary hypertension at t0, Ppa was 24+/-5 mmHg at t0 versus 20+/-7 mmHg at t5 (NS). We conclude that the significant decrease of forced expiratory volume in one second after 5 yr follow-up was related to a high percentage of smokers and exsmokers in the study population. Daytime arterial oxygen tension and pulmonary artery pressure remained stable in an unselected series of 65 obstructive sleep apnoea syndrome patients treated for 5 yrs with nasal continuous positive airway pressure, unlike arterial carbon dioxide tension, which increased by a small, but significant, amount.

Respiratory effort during obstructive sleep apnea: role of age and sleep state

OBJECTIVE

To evaluate the patients' individual characteristics predictive of the degree of respiratory effort developed during obstructive sleep apneas (OSAs).

DESIGN

Prospective consecutive sample, collection of clinical and polysomnographic data.

SETTING

University teaching hospital.

PATIENTS

One hundred sixteen consecutive OSA patients with clinical symptoms of OSA and more than 20 apneas per hour of sleep.

MEASUREMENTS

Anthropomorphic data, daytime blood gas values, and polysomnographic data. From esophageal pressure measurements during sleep, three indexes of respiratory effort during OSAs were derived: the maximal end-apneic esophageal pressure swing (PesMax), the increase in esophageal pressure swing (deltaPes) during the apnea, and its ratio to apnea duration (RPes).

RESULTS

The indexes of respiratory effort were significantly lower in rapid eye movement (REM) than in non-REM sleep (PesMax: 50.9+/-2.5 vs 39.6+/-1.9 cm H2O, p<0.001; deltaPes: 30.9+/-1.7 vs 23.4+/-1.4 cm H2O, p<0.001; RPes: 1.05+/-0.05 vs 0.53+/-0.03 cm H2O/s, p<0.001); therefore, a separate analysis was conducted in non-REM and in REM sleep. Indexes were also significantly lower in subgroups of older as compared to younger patients (PesMax: 55.6+/-3.5 vs 40.0+/-2.2 cm H2O, p<0.001; deltaPes: 34.2+/-2.3 vs 24.1+/-1.6 cm H2O, p=0.001; RPes: 1.21+/-0.08 vs 0.8+/-0.05 cm H2O/s, p<0.001). The three indexes were closely correlated with each other and only PesMax correlation data are reported. In non-REM sleep, age was the most important single independent correlate of PesMax (r=-0.37, p=0.000). In REM sleep, the apnea-related hypoxemia, apnea duration, and age were the main contributors to the variance of PesMax.

CONCLUSIONS

Respiratory effort in response to upper airway occlusion in OSA patients is lower in REM than in non-REM sleep and decreases with increasing age.

Elements of the olfactory signaling pathways in insect antennae

Owing to their enormous ability to recognize airborne molecules, insects have long been used as model systems for studying various aspects of olfaction. Modern biological techniques have opened new avenues for exploring the molecular mechanisms underlying the complex signaling processes in chemosensory neurons. Biochemical and molecular analyses have allowed the identification of molecular elements of the olfactory reaction pathways and have shed light on mechanisms that account for the sensitivity and specificity of the chemosensory system.

Weak peptide agonists reveal functional differences in B7-1 and B7-2 costimulation of human T cell clones

The influence of costimulation on the T cell response to altered peptide ligands that act as either partial or weak agonists for human CD4+ T cell clones was examined. Using stable Chinese hamster ovary (CHO) cell transfectants expressing DR2 (DRB1*1501) and human B7-1 or B7-2 as APC, presentation of native myelin basic protein (MBP) p85-99 peptide Ag or a partial agonist of MBP p85-99 induced equivalent T cell activation as measured by [3H]TdR incorporation and cytokine secretion. In marked contrast, presentation of cross-reactive peptides of MBP p85-99 that act as weak agonists with B7-1, but not B7-2, costimulation resulted in significant T cell activation as measured by [3H]TdR incorporation and cytokine secretion. These data suggest that decreasing the strength of the signal provided to the TCR allows differences in B7-1 and B7-2 signaling to be observed. Thus, the costimulatory environment during T cell activation may be a mechanism of regulating T cell cross-reactivity in the periphery.

Weak peptide agonists reveal functional differences in B7-1 and B7-2 costimulation of human T cell clones

The influence of costimulation on the T cell response to altered peptide ligands that act as either partial or weak agonists for human CD4+ T cell clones was examined. Using stable Chinese hamster ovary (CHO) cell transfectants expressing DR2 (DRB1*1501) and human B7-1 or B7-2 as APC, presentation of native myelin basic protein (MBP) p85-99 peptide Ag or a partial agonist of MBP p85-99 induced equivalent T cell activation as measured by [3H]TdR incorporation and cytokine secretion. In marked contrast, presentation of cross-reactive peptides of MBP p85-99 that act as weak agonists with B7-1, but not B7-2, costimulation resulted in significant T cell activation as measured by [3H]TdR incorporation and cytokine secretion. These data suggest that decreasing the strength of the signal provided to the TCR allows differences in B7-1 and B7-2 signaling to be observed. Thus, the costimulatory environment during T cell activation may be a mechanism of regulating T cell cross-reactivity in the periphery.

An evaluation of bioactive ceramic in the treatment of periodontal osseous defects

Bioglass particulates were surgically placed in the periodontal osseous defects of 12 patients. The clinical parameters studied were probing depth, attachment level as measured with the Florida Probe, and standardized bitewing radiograph comparisons. Data was collected initially, and at 3-, 6-, and 24-month posttreatment intervals. Statistically significant improvements were demonstrated in all clinical parameters studied. There was a mean probing depth reduction of 3.33 mm, a mean attachment gain of 1.92 mm, and a mean radiographic bone fill of 3.47 mm. Results were stable over the 24-month period. Ease of handling and excellent tissue response were characteristic of the material.

Sleep-related hypoxaemia in chronic obstructive pulmonary disease: causes, consequences and treatment

Worsening of hypoxaemia during sleep in patients with chronic obstructive pulmonary disease has been extensively investigated in the past 20 years owing to the development of polysomnography and to the advent of reliable transcutaneous oximeters. Sleep-related hypoxaemia is characteristic of rapid-eye-movement (REM) sleep but may be present during other sleep stages. There is a strong relationship between nocturnal O2 saturation and the level of daytime PaO2: the more pronounced daytime hypoxaemia, the more severe nocturnal hypoxaemia. Sleep-related hypoxaemia is due to a variable combination of alveolar hypoventilation and ventilation-perfusion mismatching, alveolar hypoventilation being the preponderant mechanism during REM sleep. The deleterious effects of sleep-related hypoxaemia include cardiac arrhythmias, 'hypoxaemic stress' on the coronary circulation and especially, peaks of pulmonary hypertension. The treatment of nocturnal hypoxaemia is conventional O2 therapy (both nighttime and daytime) in patients who exhibit marked daytime hypoxaemia (PaO2 < 55-60 mm Hg). At present data are not sufficient for justifying the use of isolated nocturnal O2 therapy in patients with nocturnal desaturation who do not qualify for conventional O2 therapy.

[Excessive daytime sleepiness]

When it is not due to an extrinsic origin, somnolence may be the main symptom of various diseases. Among these causes of excessive daytime sleepiness, obstructive sleep apnea syndrome is noteworthy for its very important prevalence, estimated at 4% in adult males. Due to repeated upper airway obstructions during sleep, this disease is efficiently treated by continuous positive airway pressure applied through a nasal masks during sleep. Another syndrome, periodic limb movements during sleep may also lead to a sleep fragmentation at the origin of daytime sleepiness. Its treatment is principally based on dopaminergic agonists. Narcolepsy-cataplexy and idiopathic hypersomnia are two causes of excessive daytime sleepiness in young people. The first is as frequent as multiple sclerosis and the second is ten times less frequent. The treatment of these two diseases is now based on a new French drug: modafinil(Modiodal). Sleep pathology still has only a small place in medical training. Excessive daytime sleepiness is therefore often misdiagnosed. In addition to their major risk of work or road accidents, numerous untreated patients continue to suffer from this very unpleasant symptom, at the origin of a major social handicap.

Genital shedding of human immunodeficiency virus type 1 DNA during pregnancy: association with immunosuppression, abnormal cervical or vaginal discharge, and severe vitamin A deficiency

The presence of human immunodeficiency virus type 1 (HIV-1) in genital secretions may be a determinant of vertical HIV-1 transmission. Cervical and vaginal secretions from HIV-1-seropositive pregnant women were evaluated to determine prevalence and correlates of HIV-1-infected cells in the genital tract. HIV-1 DNA was detected by polymerase chain reaction in 32% of 212 cervical and 10% of 215 vaginal specimens. Presence of HIV-1 DNA in the cervix was associated with cervical mucopus and a significantly lower absolute CD4 cell count (354 vs. 469, P < .001). An absolute CD4 cell count <200 was associated with a 9.6-fold increased odds of cervical HIV-1 DNA detection compared with a count > or = 500 (95% confidence interval, 2.8-34.2). Detection of vaginal HIV- 1 DNA was associated with abnormal vaginal discharge, lower absolute CD4 cell count, and severe vitamin A deficiency. Presence of HIV-1-infected cells in genital secretions was associated with immunosuppression and abnormal cervical or vaginal discharge.

Expression of an olfactory receptor in Escherichia coli: purification, reconstitution, and ligand binding

An olfactory receptor has been expressed in bacterial cells as a fusion protein with glutathione S-transferase (GST). Overexpression of receptor protein yielding about 10% of the cell protein was achieved with mutants lacking the N-terminus and the first transmembrane region or with mutants carrying three positively charged residues in the first intracellular loop. The overexpressed fusion protein accumulated in inclusion bodies and could be solubilized in detergent. It was purified by metal chelation chromatography based on a C-terminal 6-histidine tag, and the GST portion was removed after proteolytic cleavage. The purified receptor was reconstituted into lipid vesicles and specific binding of odor ligands was shown by photoaffinity labeling and tryptophan fluorescence measurements. Thus, for the first time, an odorant receptor/ligand pair becomes available in large amounts for biophysical and screening studies.

[Sleep-related respiratory disorders]

Sleep-related respiratory disorders are mainly represented by the consequences of partial or total upper airway obstruction during sleep, which lead to clinical pictures ranging from "pure" snoring to full-blown obstructive sleep apnea syndrome, including obstructive sleep hypopnea syndrome and upper airway resistance syndrome. These pictures share symptoms like snoring and excessive daytime sleepiness. Beyond the social and professional impairment and the increased risk of traffic and work accidents, these patients are exposed to the complications of systemic hypertension, which is often associated, and of less frequent cardiorespiratory failure. The diagnosis is based upon polysomnography which demonstrates the ventilation abnormalities. Since stable weight loss is most often impossible to obtain, the treatment of choice is based on nasal continuous positive airway pressure during sleep. In some selected cases, facial bone surgery may be helpful.

Role of chemosensitivity in intrathoracic pressure changes during obstructive sleep apnea

We tested the hypothesis that the awake ventilatory response to hypoxia and hypercapnia may contribute to the variability of respiratory effort developed in response to upper airway obstruction in obstructive sleep apnea syndrome. The polygraphic recordings of 38 patients diagnosed as having obstructive sleep apnea on the basis of an apnea+hypopnea index greater than 10 were examined. All subjects received hypoxic and hypercapnic ventilatory tests the day before the nocturnal polysomnography. Thirty apneas during non-rapid eye movement (NREM) sleep and at least 10 apneas during rapid eye movement sleep were analyzed. For each considered apnea, we measured esophageal pressure (Pes) swings during the first three breaths preceding apnea and during the first three and last three occluded efforts occurring during the apnea. We considered as indices of respiratory effort the overall increase from the minimum to the maximum Pes (delta Pes), the rate of increase of Pes during apnea (RPes), and the maximal respiratory effort at the end of apnea (Pes max fin). In NREM sleep, all three indices of respiratory effort were correlated positively with the awake ventilatory response to hypoxia or hypercapnia and with the apnea index. No correlation was found between the indices of respiratory effort and body mass index, age, pulmonary function tests, awake blood gases, apnea duration, and apnea desaturation. In rapid eye movement sleep, none of the considered variables predicted the degree of respiratory effort. In conclusion, our results suggest that the degree of ventilatory response to upper airway occlusion in obstructive sleep apnea may be influenced by the sensitivity of central neural drive to chemical stimuli.

Long-term compliance with CPAP therapy in obstructive sleep apnea patients and in snorers

A prospective study aimed at objectively evaluating compliance with nasal continuous positive airway pressure (CPAP) treatment was conducted in 728 obstructive sleep apnea [OSA; apnea/hypopnea index (AHI) > 15 events/hour] patients and 98 nonapneic snorers (AHI < or = 15 events/hour). Five-hundred seventy-five OSA patients and 33 nonapneic snorers underwent CPAP therapy and were followed-up for an average of 1,176 +/- 38 days (27 to 4,203 days). Compliance to treatment was measured by the mean rate of use of the CPAP device obtained from a built-in time counter. Acceptance of treatment was measured using Kaplan-Meier's model. The acceptance of CPAP was greater than 90% at 3 years and greater than 85% at 7 years in OSA patients. It was greater than 60% at 3 years in nonapneic snorers. The mean rate of CPAP use was 5.7 +/- 1.8 hours/day in OSA patients and 5.6 +/- 1.4 hours/day in snorers who were still on CPAP on October 1, 1995. It was correlated positively with age, body mass index, and AHI, and it was correlated negatively with daytime partial pressure of oxygen (PaO2), forced expiratory volume in 1 second (FEV1), and vital capacity in the group of OSA patients. This study shows that CPAP therapy is reasonably accepted by OSA patients as well as by nonapneic snorers. Both within and between groups, objective disease severity (as measured by the respiratory event index and daytime and nighttime hypoxemia), rather than patients' symptoms or complaints, seemed to play a role in the quality of compliance to treatment.

Long-term compliance with CPAP therapy in obstructive sleep apnea patients and in snorers

A prospective study aimed at objectively evaluating compliance with nasal continuous positive airway pressure (CPAP) treatment was conducted in 728 obstructive sleep apnea [OSA; apnea/hypopnea index (AHI) > 15 events/hour] patients and 98 nonapneic snorers (AHI < or = 15 events/hour). Five-hundred seventy-five OSA patients and 33 nonapneic snorers underwent CPAP therapy and were followed-up for an average of 1,176 +/- 38 days (27 to 4,203 days). Compliance to treatment was measured by the mean rate of use of the CPAP device obtained from a built-in time counter. Acceptance of treatment was measured using Kaplan-Meier's model. The acceptance of CPAP was greater than 90% at 3 years and greater than 85% at 7 years in OSA patients. It was greater than 60% at 3 years in nonapneic snorers. The mean rate of CPAP use was 5.7 +/- 1.8 hours/day in OSA patients and 5.6 +/- 1.4 hours/day in snorers who were still on CPAP on October 1, 1995. It was correlated positively with age, body mass index, and AHI, and it was correlated negatively with daytime partial pressure of oxygen (PaO2), forced expiratory volume in 1 second (FEV1), and vital capacity in the group of OSA patients. This study shows that CPAP therapy is reasonably accepted by OSA patients as well as by nonapneic snorers. Both within and between groups, objective disease severity (as measured by the respiratory event index and daytime and nighttime hypoxemia), rather than patients' symptoms or complaints, seemed to play a role in the quality of compliance to treatment.

Cloning of biogenic amine receptors from moths (Bombyx mori and Heliothis virescens)

Based on the similarity of genes which code for guanine-nucleotide binding protein- (G-protein-) coupled receptors, cDNA clones encoding new members of the receptor family have been isolated from Bombyx mori and Heliothis virescens. The deduced protein structures exhibit highest similarity to tyramine/octopamine and serotonin receptors of Drosophila. One of the receptor clones (K50Hel) was permanently expressed in the mammalian cell line LLC-PK1. In stimulation experiments its responded to octopamine leading to an inhibition of adenylate cyclase activity in a dose-dependent manner. Pharmacological studies revealed a higher affinity for mianserin than for yohimbine suggesting, that the K50Hel clone encoded a neuronal type 3 octopamine receptor. As revealed by in situ hybridization, this receptor type is expressed in the central nervous system and antennae of moth.

Respiratory effort during sleep apneas after interruption of long-term CPAP treatment in patients with obstructive sleep apnea

Apneas generally reappear in patients with obstructive sleep apnea (OSA) when treatment with continuous positive airway pressure (CPAP) is interrupted. However, a single-night treatment interruption may be associated with a lesser severity of sleep apneas than before treatment. We hypothesized that this decrease in severity of sleep apneas reflects changes in the respiratory response to upper airway obstruction. Therefore, we compared indexes of respiratory effort during sleep in 25 patients with OSA before and after 1 year of CPAP treatment. Respiratory effort was assessed by means of an esophageal balloon. After 1 year of CPAP treatment, there was a decrease in the maximal end-apneic esophageal pressure swings (Pes) (from 56.7 +/- 5.4 to 30.3 +/- 2.6 cm H2O; p = 0.000; mean +/- SEM), in the overall increase in Pes during an apnea (35.2 +/- 3.6 vs 16.5 +/- 1.5 cm H2O; p = 0.000), as well as the rate of increase in Pes (1.1 +/- 0.1 vs 0.6 +/- 0.1 cm H2O/s; p = 0.000). Although body mass index (BMI) did not change significantly, the individual changes in BMI significantly correlated with the changes in respiratory effort after 1 year of CPAP treatment. Apnea duration and apnea-related oxygen desaturation also decreased significantly. We conclude that long-term CPAP treatment induces changes in respiratory control that persist at least on the first night of treatment interruption.