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At least 19 recordsLinked to original sources

PubMed1996

Videoradiography of patients with habitual snoring and/or sleep apnea. Technical description and presentation of videoradiographic results during sleep concerning occurrence of apnea, type of apnea, and site of obstruction.

PURPOSE: The videoradiographic examination described was designed for habitual snorers and sleep apnea syndrome (SAS) patients and was performed during wakefulness and sleep. During wakefulness the purpose was to reveal any dysfunction in deglutition and speech as well as morphologic abnormalities. The purpose during sleep, which usually was induced by low-dose midazolam intravenously, was to reveal the site and form of obstruction in obstructive sleep apnea patients and the site of snoring in habitual snorers. MATERIAL: The preoperative results of 104 patients are presented. In 57 patients who had apneas, the occurrence and type of apnea could be determined. RESULTS AND CONCLUSION: A continuous recording over some minutes gave a rough estimate of the degree of SAS and mean duration of apnea. Although much information on SAS can be obtained by this method, it cannot replace polygraphic sleep recording in the investigation of habitual snorers and SAS patients. However, these 2 methods are complementary and can be performed simultaneously as polygraphic videoradiography.

Barium Sulfate↗

PubMed2003

Obstructive sleep apnea in epilepsy patients: the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ) is a useful screening instrument for obstructive sleep apnea in a disease-specific population.

OBJECTIVE: To determine useful cutoffs on the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ) in an epilepsy population. BACKGROUND: Epilepsy and obstructive sleep apnea (OSA) frequently coexist, and treating OSA in epilepsy patients may reduce seizure frequency and improve daytime sleepiness. The SA-SDQ, a 12-item validated measure of sleep-related breathing disorders, may be a useful tool to screen epilepsy patients for OSA, although appropriate cutoff points have not been established in this population. Previously suggested SA-SDQ cutoff points for OSA in a non-epilepsy population were 32 for women and 36 for men. PATIENTS AND METHODS: One hundred twenty-five subjects with epilepsy undergoing polysomnography completed a survey about their sleep, including the 12-item SA-SDQ scale. Receiver-operating characteristics curves were constructed to determine optimal sensitivity and specificity. RESULTS: Sixty-nine of the 125 subjects (45%) had apnea-hypopnea indices greater than five, indicating OSA. The area under the curve was 0.744 for men and 0.788 for women. For men, an SA-SDQ score of 29 provided a sensitivity of 75% and a specificity of 65%. For women, an SA-SDQ score of 26 provided a sensitivity of 80% and a specificity of 67%. CONCLUSIONS: The SA-SDQ is a useful screening instrument for OSA in an epilepsy population. Our results indicate that the previously suggested cutoffs for OSA (36 for men and 32 for women) may be too high for this specific population. We suggest screening cutoffs of 29 for men and 26 for women.

Disorders of Excessive Somnolence↗

PubMed2000

Nasal intermittent positive pressure ventilation (NIPPV) versus nasal continuous positive airway pressure (NCPAP) for apnea of prematurity.

BACKGROUND: Apnea of prematurity is almost universal in infants who are born before 34 weeks gestation. Previous randomised trials and systematic reviews have found methylxanthines to be effective in preventing apnea of prematurity. However, recent concerns about potential long term side effects of methylxanthines on the neurodevelopment of low birth weight infants have led to an increased interest in alternate methods of treating apnea of prematurity. Nasal continuous positive airway pressure (NCPAP) is a useful method of respiratory support which reduces the incidence of obstructive or mixed apnea. However, apneic infants managed with NCPAP, with or without methylxanthines, sometimes require endotracheal intubation with its attendant morbidity and cost. Nasal intermittent positive pressure ventilation (NIPPV) is a simple, effective mode of respiratory support for older children and adults. It has been used to treat apnea in preterm infants but case reports of gastrointestinal perforations have limited its widespread use. OBJECTIVES: In preterm infants with recurrent apnea, does treatment with NIPPV lead to a greater reduction in apnea and need for intubation and mechanical ventilation, as compared with treatment with NCPAP? Does NIPPV increase the incidence of gastrointestinal complications, i.e. gastric distension leading to cessation of feeds, or perforation? SEARCH STRATEGY: Medline was searched (1966-2000) using the MeSH terms: infant, newborn (exp) and positive-pressure respiration (exp). Other sources included the Cochrane Controlled Trials Register and CINAHL (search terms: infant, newborn and intermittent positive pressure ventilation); also used were expert informants, previous reviews including cross-references, and conference and symposia proceedings. SELECTION CRITERIA: All randomised and quasi-randomised trials were included. Participants included unventilated preterm infants experiencing apnea of prematurity. Interventions compared were intermittent positive pressure ventilation administered via the nasal route, either by short nasal prongs or nasopharyngeal tube, and nasal CPAP delivered by the same methods. Types of outcome measures: - failure of therapy as defined by apnea that is frequent or severe requiring additional ventilatory support - rates of endotracheal intubation - rates of apnea and bradycardia expressed as events per hour - gastrointestinal complications i.e. abdominal distension requiring cessation of feeds, or GI perforation DATA COLLECTION AND ANALYSIS: Data were extracted independently by the three reviewers. The trials were analysed using relative risk (RR), risk difference (RD) and number needed to treat (NNT) for dichotomous data; means and weighted mean difference (WMD) were used for continuous data. MAIN RESULTS: Two trials, enrolling 54 infants in total, fulfilled the inclusion criteria. Both reported only the short term results (4 to 6 hours) of the interventions. Only one infant (randomised to NCPAP) required intubation during this period. Ryan (1989), in a cross over study of 20 infants, showed no significant difference in rates of apnea (events/hr) between the 2 interventions (WMD -0.10 (-0.53,0. 33)). Lin (1998) randomised 34 infants and demonstrated a greater reduction in frequency of apneas (events/hr) with NIPPV compared to NCPAP (WMD -1.19 (-2.31,-0.07)). Meta-analysis of both trials showed no difference in pCO2 (mmHg) at the end of the 4-6 hour study period (WMD 0.95 (-3.05,4.94)). No data were reported on gastrointestinal complications. REVIEWER'S CONCLUSIONS IMPLICATIONS FOR PRACTICE: NIPPV may be a useful method of augmenting the beneficial effects of NCPAP in preterm infants with apnea that is frequent or severe. Its use appears to reduce the frequency of apneas more effectively than NCPAP. Additional safety and efficacy data are required before recommending NIPPV as standard therapy for apnea. IMPLICATIONS FOR RESEARCH: Future trials with sufficient power should assess the efficacy (reduction in failure of therapy) and safety (GI complications) of NIPPV. Outcomes should be assessed throughout the entire period during which the infant requires assisted ventilation. The recent ability to synchronise NIPPV with an infant's spontaneous respirations is a promising development requiring further assessment.

Apnea↗

PubMed1992

Influence of continuous positive airway pressure on sleep apnea-related desaturation in sleep apnea patients.

To investigate the influence of nasal continuous positive airway pressure (CPAP) on apnea-related desaturation, we compared the sleep apnea-related desaturations obtained during a polysomnographic study before and during nasal CPAP in 15 sleep apnea patients. An individual desaturation curve was determined with a regression analysis by plotting the lowest SaO2 value reached during each apnea against its duration; these data were collected throughout the night. At baseline, we only considered the apneas with a preapneic SaO2 value greater than 90% and a minimal SaO2 value above or equal to 60%. For the CPAP study, the preapneic SaO2 value also had to be within 2% the baseline value for the apneas to be retained. Due to the restriction criteria imposed to characterize apnea-related SaO2 falls, residual apneas still had to be recorded with CPAP. These data were analyzed separately for obstructive apnea for non-rapid eye movement (REM) and REM sleep stages. A desaturation curve was obtained from 10 sec to a variable upper limit that corresponded to the longest apnea duration commonly reached during both baseline and CPAP for a given apnea-type and sleep stage. The individual apnea-related SaO2 fall was characterized by measuring a desaturation area corresponding to the area under the curve. It was expressed in % SaO2/sec of apnea. CPAP reduced the number of apneas per hour of sleep from 37.5 +/- 6.5 (mean +/- SEM) to 14.3 +/- 3.7 (p = 0.001), and improved the whole night SaO2 level as estimated by a cumulative SaO2 curve. The mean apnea duration was reduced from 22.9 +/- 1.5 sec at baseline to 16.8 +/- 0.5 sec during CPAP therapy (p = 0.005). The preapneic SaO2 value was 94.8 +/- 0.3% at baseline and 95.5 +/- 0.2% during CPAP (p = 0.5). The desaturation area decreased from 267 +/- 48% SaO2/sec at baseline to 152 +/- 41% SaO2/sec during CPAP (p less than 0.001). We conclude that CPAP improves the apnea-related desaturation independently of the shortening of apneas and of any difference in the preapneic SaO2 value.

Female↗

PubMed2000

Continuous positive airway pressure versus theophylline for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Theophylline stimulation of breathing and continuous positive airways pressure have been used to prevent apnea and its consequences. OBJECTIVES: The main objective was to determine in preterm infants with recurrent apnea, if treatment with CPAP compared with treatment with theophylline leads to a clinically important reduction in apnea or use of mechanical ventilation, without clinically important side effects. SEARCH STRATEGY: The standard search strategy of the Neonatal Review Group was used. This includes searches of the Oxford Database of Perinatal Trials, Cochrane Controlled Trials Register, MEDLINE, previous reviews including cross references, abstracts, conferences, symposia proceedings, expert informants and journal hand searching mainly in the English language. SELECTION CRITERIA: All trials using random or quasi-random allocation to CPAP or theophylline in preterm infants with clinical recurrent apnea/bradycardia were eligible. DATA COLLECTION AND ANALYSIS: Data were extracted using standard methods of the Cochrane Collaboration and its Neonatal Review Group, with separate evaluation of trial quality and data extraction by each author and synthesis of data using relative risk. MAIN RESULTS: The use of mask CPAP is associated with a higher treatment failure rate as measured by less than a 50% reduction in apnea or use of the alternative treatment [RR 2.89 (95% CI 1.12,7.47); RD 0.42 (95% CI 0. 11, 0.74)]. For every 2.4 infants (95% CI 1.4, 9.5) treated with mask CPAP rather than theophylline, there results one treatment failure. In the mask CPAP group there is more use of IPPV [RR 3.09 (1.42,6.70; RD 0.58 (95% CI 0.30, 0.86). For every 1.7 infants (95% CI 1.2, 3.3) treated with mask CPAP rather than theophylline, one infant is intubated for IPPV. In the mask CPAP group, there are trends towards more deaths in the first year, and in death or major disability in survivors at follow up, which do not reach significance. There are no differences in rates of necrotizing enterocolitis or major disability in survivors at follow up. REVIEWER'S CONCLUSIONS: Theophylline is more effective than mask CPAP for preterm infants with apnea. Since CPAP is no longer administered by mask, the results of this review have limited importance for current clinical practice. Further evaluation of the benefits and harms of CPAP vs theophylline for preterm infants with apnea requires further trials in which CPAP is administered by current methods.

Apnea↗

PubMed2000

Doxapram treatment for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Doxapram has been used to stimulate breathing and so prevent apnea and its consequences. OBJECTIVES: In preterm infants with recurrent apnea, does treatment with doxapram lead to a clinically important reduction in apnea and use of Intermittent positive airways pressure (IPPV), without clinically important side effects? SEARCH STRATEGY: Searches were made of the Oxford Database of Perinatal trials, the Cochrane Collaboration Clinical Trials Register, MEDLINE (using text words 'doxapram', 'apnea or apnoea' and Mesh term 'infant, premature') previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants, mainly in the English language. Also an expert informant's search in the Japanese language was made by Prof. Y. Ogawa in 1996. SELECTION CRITERIA: All trials utilising random or quasi-random patient allocation, in which doxapram was used for the treatment of apnea in preterm infants were included. DATA COLLECTION AND ANALYSIS: Each author evaluated the papers for quality and inclusion criteria. Independent data extraction was carried out. MAIN RESULTS: Only one trial, which randomized 11 infants to intravenous doxapram and 10 infants to placebo, was found. There were fewer treatment failures after 48 hours in the group of preterm infants treated with doxapram (4/11) compared with the group treated with placebo (8/10). The wide confidence intervals made this result non-significant [RR 0.45 (0.20, 1.05)]. Only one infant, who was from the placebo group, was given IPPV. Of the seven responders by 48 hours in the group of 11 who received doxapram, five failed to respond between 48 hours and seven days after commencement of therapy. This gives a late failure rate of 9/11, similar to the short term failure rate in the placebo group of 8/10. It is not possible to evaluate the late responses of all those in the placebo group since they crossed over to a treatment arm. REVIEWER'S CONCLUSIONS: Although intravenous doxapram might reduce apnea within the first 48 hours of treatment, there are insufficient data to evaluate the precision of this result or to assess potential adverse effects. No longterm outcomes have been measured. Further studies are needed to determine the role of this treatment in clinical practice.

Apnea↗

PubMed2000

Doxapram versus methylxanthine for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Doxapram and methylxanthine drugs have been used to stimulate breathing and so prevent apnea and its consequences. OBJECTIVES: In preterm infants with recurrent apnea, how does treatment with doxapram compare with treatment with theophylline in leading to a clinically important reduction in apnea and use of mechanical ventilation, without clinically important side effects. SEARCH STRATEGY: The standard search strategy of the Neonatal Review Group, as outlined in the Cochrane Library, was used. SELECTION CRITERIA: All trials utilising random or quasi-random patient allocation, in which doxapram was compared with methylxanthine (e.g. theophylline) for the treatment of apnea, were eligible. There must have been an effort to exclude specific causes of apnea. DATA COLLECTION AND ANALYSIS: The standard methods of the Cochrane Collaboration and its Neonatal Review Group were used to select trials, assess quality and to extract and synthesize data. The methodological quality of each trial was reviewed by the second author blinded to trial authors and institution(s). Additional information was requested from authors to clarify methodology. Each author extracted the data separately, then they were compared and differences resolved. Meta-analysis was carried out with use of relative risk and risk difference. MAIN RESULTS: In these trials involving a relatively small number of preterm infants with apnea of prematurity, there is no apparent difference between the effect of intravenous treatment with doxapram or methylxanthine on the incidence of apnea within 48 hours. There were no infants reported to have been given mechanical ventilation on either treatment. No adverse effects were reported. REVIEWER'S CONCLUSIONS: Implications for practice. The overall results of these small trials suggest that intravenous doxapram and intravenous methylxanthine are not different in their effectiveness in the short term in the treatment of apnea of prematurity. Caution is warranted as the number of patients in these trials is too small to exclude an important difference between these two treatments or to exclude the possibility of less common side effects. Longer term outcome of infants treated in these trials has not been reported. Implications for research. Further studies would require a large number of infants, stratified by gestation, to clarify which infants are likely to benefit and whether there might be differences in responses or side effects with these two drugs at different ages. It would be valuable to include important clinical outcomes such as use of mechanical ventilation as well as subsequent growth and development in future studies. Responses to treatment would have to take account of co-interventions, such as nasal continuous airway pressure which is frequently used post-intubation.

Aminophylline↗

PubMed2000

Methylxanthine treatment for apnea in preterm infants.

BACKGROUND: Recurrent apnea is common in preterm infants, particularly at very early gestational ages. These episodes of loss of effective breathing can lead to hypoxemia and bradycardia which may be severe enough to require resuscitation including use of positive pressure ventilation. Methylxanthines have been used to stimulate breathing and prevent apnea and its consequences. OBJECTIVES: The objective of this review is to determine if methylxanthine treatment in preterm infants with recurrent apnea leads to a clinically important reduction in apnea and use of intermittent positive pressure ventilation (IPPV), without clinically important side effects. SEARCH STRATEGY: Searches were made of the Oxford Database of Perinatal Trials, MEDLINE, EMBASE, previous reviews including cross references, abstracts of conferences and symposia proceedings, expert informants, journal handsearching mainly in the English language. SELECTION CRITERIA: All trials utilising random or quasi-random patient allocation, in which methylxanthine (theophylline or caffeine) was compared with placebo or no treatment for apnea in preterm infants, were included. DATA COLLECTION AND ANALYSIS: Methodological quality was assessed independently by the two authors. Data were extracted independently by the two authors. Treatment effects were expressed as relative risk (RR) and risk difference (RD) and their 95% confidence intervals, using a fixed effect model. For significant results, the inverse of the risk difference (1/RD) was used to calculate the number needed to treat (NNT). MAIN RESULTS: The results of four trials which enrolled a total of 110 preterm infants with apnea indicate that methylxanthine therapy leads to a reduction in apnea and use of IPPV in the first 2 - 7 days. There are insufficient data to evaluate side effects and no data to examine effects within different gestational age groups. There are no trial data which examine long term effects. REVIEWER'S CONCLUSIONS: Methylxanthines are effective in reducing the number of apneic attacks and the use of mechanical ventilation in the two to seven days after starting treatment. In view of its lower toxicity, caffeine would be the preferred drug. Although the safety of methylxanthine therapy has been suggested in cohort studies, there are no trial data on longterm outcome. In order to indicate which infants are likely to benefit from treatment, there is a need for stratification by gestation and/or other risk factors in future studies. In any future studies the longer term effects of treatment on growth and development should be evaluated.

Apnea↗

PubMed2000

Kinesthetic stimulation for preventing apnea in preterm infants.

Apnea↗

PubMed1996

Effect of topical upper airway anesthesia on apnea duration through the night in obstructive sleep apnea.

It has previously been reported that the duration of obstructive apneas increases from the beginning to the end of the night (M. Charbonneau, J. M. Marin, A. Olha, R. J. Kimoff, R. D. Levy, and M. Cosio. Chest 106: 1695-1701, 1994). The purpose of this study was to test the hypothesis that stimulation of upper airway (UA) sensory receptors during obstructed inspiratory efforts contributes to arousal and apnea termination and that a progressive attenuation of this mechanism through the night contributes to apnea lengthening. We studied seven patients (six men, one woman) with severe obstructive sleep apnea (apnea-hypopnea index = 93 +/- 26 events/h) during two consecutive nights of polysomnographic monitoring. On one night (random order), we performed topical UA anesthesia with 0.2% tetracaine and on the control night, sham anesthesia. We measured apnea duration, esophageal pressure (Pes) during apneas, and apneic O2 desaturation. Consistent with previous findings, apnea duration, number of efforts per apnea, and peak Pes at end apnea increased from the beginning to the end of the control nights. UA anesthesia produced a significant increase in apnea duration at the beginning of the night but no change in apnea length at the end of the night. Peak Pes and the rate of increase in Pes during the anesthesia nights were greater than during control nights, but the rate of increase in Pes was similar for the beginning and end of the control and anesthesia nights. These findings suggest that UA sensory receptors play a role in mediating apnea termination at the beginning of the night but that the contribution of these receptors diminishes as the night progresses such that greater inspiratory efforts are required to trigger arousal, leading to apnea prolongation.

Adult↗

PubMed1985

A shift from central and mixed sleep apnea to obstructive sleep apnea resulting from low-flow oxygen.

Low-flow oxygen decreases the frequency of the 3 types of apnea (central, mixed, and obstructive) in patients with predominantly obstructive sleep apnea. The decrease in frequency appears to be accompanied by a shift in apnea distribution, consisting of a decrease in the proportion of central and mixed apneas and an increase in that of obstructive apneas. To determine whether this shift represents a greater inhibitory effect on central and mixed apneas or an increased tendency toward obstructive apneas, we administered low-flow oxygen during sleep to 9 patients who demonstrated predominantly central and mixed sleep apnea (51 +/- 33% and 33 +/- 21% of apneic events, respectively, mean +/- SD) and had resting, room air, oxygen tensions of 83 +/- 11 mmHg. During non-REM sleep, oxygen increased the baseline oxyhemoglobin saturation while reducing the average peak fall in oxyhemoglobin saturation during each apneic event. Oxygen reduced the overall apnea frequency from 66 +/- 7.8 (mean +/- SE) to 43.0 +/- 10.7 episodes per hour (p less than 0.02). Central and mixed apneas decreased markedly from 31.4 +/- 0.6 to 6.4 +/- 4.3 episodes per hour (p less than 0.02) and from 20.9 +/- 5.0 to 4.9 +/- 1.5 episodes per hour (p less than 0.02), respectively. However, obstructive apnea frequency more than doubled from 13.9 +/- 7.0 to 32.1 +/- 9.2 episodes per hour (p less than 0.02). We conclude that in these patients oxygen tension altered both the frequency and distribution of sleep-induced apnea, with a lower oxygen tension increasing the frequency of central and mixed apneas and a higher oxygen tension increasing the frequency of obstructive apneas.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗

PubMed1996

Mechanism of apnea lengthening across the night in obstructive sleep apnea.

We have previously shown in patients with obstructive sleep apnea (OSA) that the length of apneas increases from the beginning to the end of the night (Chest 1994;106:1695-1701). To investigate this, in light of recent evidence that neural feedback related to inspiratory effort during apneas plays an important role in apnea termination (Am. J. Respir. Crit. Care Med. 1994;149:707-714), we measured transdiaphragmatic pressure (Pdi) and the diaphragm tension-time index (TTdi = Pdi/Pdi(max)) Ti/Ttot) during overnight polysomnography in seven male subjects with severe OSA (mean apnea-hypopnea index [AHI] = 64.1 +/- 8.8 [SD] events/h). We assessed apnea duration, SaO2, and inspiratory effort during apneas at the start and end of the night in Stage 2 sleep. Mean apnea duration increased from 26.6 +/- 2.0 s (SEM) to 32.6 =/- 2.5 s (p < 0.05). The rate of fall in SaO2 during apneas decreased, and end-apneic SaO2 remained unchanged across the night, suggesting a possible role for metabolic factors in mediating the increase in apnea duration. Both Pdi and TTdi at end-apnea just prior to arousal increased significantly from the beginning to the end of the night (e.g., Pdi from 41.0 +/- 4.9 to 49.9 +/- 7.9 cm H20; p < 0.05). These findings, together with those in previous studies, suggest that there is a blunting over the night of the arousal response to neural stimuli produced during obstructed inspiratory effort, which plays a major role in mediating apnea lengthening across the night in OSA.

Arousal↗

PubMed1982

Effects of obstructive sleep apneas on transcutaneous oxygen pressure in control infants, siblings of sudden infant death syndrome victims, and near miss infants: comparison with the effects of central sleep apneas.

In order to investigate the effects of obstructive sleep apneas upon transcutaneous PO2 75 polysomnograms, recorded during night sessions in 25 control infants, 25 siblings, and 25 near miss for sudden infant death syndrome (SIDS) infants were studied. These observations were compared with the decreases in transcutaneous PO2 measured during central sleep apneas in the same infants. During a total of 707.6 hours of sleep, 33 obstructive apneas and 1,650 central apneas were recorded. Obstructive apneas were seen in three control infants (three episodes), one sibling (five episodes), and six near miss for SIDS infants (25 episodes). The obstructive apneas tended to be short (less than 10 seconds). Comparatively, the central apneas were equally distributed in the three groups of infants, and only the near miss children presented apneas that lasted as long as 19 seconds. The decrease in transcutaneous PO2 was proportional to the duration of both types of apnea, but for a given duration the decrease in transcutaneous PO2 was significantly greater for the obstructive apneas than for the central apneas (with a mean difference of 7.59 +/- 0.53% PO2. It is concluded that the hypoxic effects of the obstructive apneas might have important clinical implications in infants, such as the near miss for SIDS.

Female↗

PubMed1994

Mechanisms of apnea termination in obstructive sleep apnea. Role of chemoreceptor and mechanoreceptor stimuli.

Previous work from our laboratory has indicated that mechanoreceptor feedback from the respiratory muscles may play an important role in arousal and apnea termination in obstructive sleep apnea (OSA). Other studies have pointed to a prominent role for chemoreceptor stimuli. We postulated that mechanoreceptor stimuli from the respiratory system are the primary determinant of apnea termination, and that chemoreceptor stimuli exert their effect indirectly through stimulation of ventilation and thus proprioceptive feedback. To test this, we measured the diaphragmatic tension-time index (TTdi) during obstructive sleep apneas in seven male subjects with severe untreated OSA. We compared the maximal TTdi values at end-apnea during administration of air, O2, and CO2. We reasoned that if mechanoreceptor stimuli mediate apnea termination, changing the degree of chemoreceptor stimulation during apneas should not alter the level of respiratory effort at end-apnea. O2 administration produced a significant increase in end-apneic arterial oxygen saturation (SaO2) and increased apnea duration. CO2 administration led to an increase in pre- and postapneic end-tidal carbon dioxide pressure (PETCO2), and tended to shorten apneas. However, the mean value for maximal end-apneic TTdi was 0.12 +/- 0.01 (SEM) during room air breathing and was unaltered by O2 (0.12 +/- 0.01) or CO2 (0.11 +/- 0.01) administration. The consistency of end-apneic TTdi values despite the varying chemical drive supports the hypothesis that apnea termination in OSA is mediated by mechanoreceptor feedback from the respiratory system, most likely from the respiratory muscles. The influence of chemoreceptor information may be mediated indirectly through an effect on ventilatory effort.

Adult↗

PubMed1988

Prolonged apnea associated with upper airway protective reflexes in apnea of prematurity.

We examined the hypothesis that most idiopathic prolonged apneic spells in preterm infants originate as a form of upper airway protective reflex. We elicited a previously described upper airway reflex in 10 sleeping preterm infants with apnea of prematurity by instilling physiologic saline into the oropharynx and recording respiration, heart rate, and swallowing. Immediately after a small pharyngeal bolus of warm saline, one or more of several characteristic airway reflex responses occurred with most stimulus trials. These responses included brief central apnea, swallowing, and obstructed inspiratory efforts. Intermittently, this response pattern was more extensive and resulted in prolonged apnea. We compared the frequency of prolonged apnea immediately after saline boluses with spontaneously occurring prolonged apnea and found that apnea frequency after saline was greater than spontaneous apnea frequency in all 10 infants (p less than 0.0025). Also, the incidence of prolonged apnea occurring immediately after saline stimuli was significantly greater than that after randomly delivered control stimuli (p less than 0.005). These observations indicate that saline can induce prolonged apnea. Swallowing, a distinctive feature of the chemoreflex, occurred during 76% of spontaneous prolonged apnea spells. Spontaneous and postsaline prolonged apnea were nearly identical with respect to general features and frequency of specific airway protective responses. We conclude that the majority of spontaneous prolonged apneic spells in preterm infants have multiple features that are characteristic of an exaggerated airway protective response to an upper airway fluid stimulus. Circumstantial evidence suggests that endogenous upper airway secretions may be an important source of stimuli-inducing apneic spells in preterm infants.

Apnea↗

PubMed1985

Apnea duration and hypoxemia during REM sleep in patients with obstructive sleep apnea.

Nocturnal sleep studies of 12 patients with obstructive sleep apnea and a matched control group of 12 subjects without the sleep apnea syndrome were analyzed to compare arterial oxyhemoglobin saturation (SaO2) during REM and non-REM sleep. Mean percentage of total sleep time spent in REM sleep was not significantly different in patients with obstructive sleep apnea and in subjects without significant apnea (14.2 +/- SEM 2.2 percent in patients vs 12.0 +/- 2.2 percent in nonapnea subjects). Apneas were longer during REM than non-REM sleep in all 12 patients (p less than 0.01). Oxyhemoglobin desaturations were more frequent during REM than non-REM sleep in both apnea patients and the control subjects. In addition, there was a greater mean fall in SaO2 per desaturation episode in both the apnea patients and non-apnea subjects. We conclude: 1) sleep apneas are longer during REM sleep than non-REM sleep in patients with obstructive sleep apnea; 2) hypoxemia is greater during REM sleep than non-REM sleep in subjects with and without the sleep apnea syndrome.

Adult↗

PubMed2001

Non-linear dynamics of cardiovascular system in humans exposed to repetitive apneas modeling obstructive sleep apnea: aggregated time series data analysis.

OBJECTIVE: Testing the hypothesis that alterations in non-linear dynamics of the cardiovascular variability appear in healthy, awake subjects during voluntary apnea. SUBJECTS AND METHODS: Ten young subjects performed 20 apneas 60 s each separated by 1 min free breathing. Inter-beat interval (IBI) measured as RR-interval in ECG, systolic (SYS) and diastolic (DIAS) arterial blood pressure. stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were non-invasively recorded and computed by Portapress 2 system. Correlation dimension according to Grassberger-Proccacia algorithm (CD) and ratio of % determinism versus % recurrence (RDR) computed from recurrence plot according to Webber and Zbiluth [J. Appl. Physiol. 76 (1994) 965] were used as the indices of chaos and complexity. Sequential time series of cardiovascular variables in consecutive 60-s apneas and inter-apnea free breathings were separately windowed and aggregated. CD and RDR of aggregated apneic time series were compared with CD and RDR values of aggregated time series of inter-apnea free breathing, 10 min at rest and 10 min recovery. Reliability of the aggregation method of sequential time series was tested on transformed simulated data generated by Lorenz model. Error in CD and RDR estimation did not exceed 5% and 1%. respectively. RESULTS: CD of cardiovascular variables computed from aggregated apneas was significantly reduced and RDR augmented versus control and recovery periods. CD and RDR values of inter-apnea phases were in between those in control and during apneas. Time domain linear variance (SD) was increased during aggregated apneas. CONCLUSIONS: Signal dynamics dependent windowing and data aggregation could be a useful tool for non-linear analysis of short repeatable sequential time series; time domain linear variability of the cardiovascular dynamics is augmented while complexity reduced during apneic chemoreceptor stimulation; alterations in non-linear dynamics of cardiovascular variables during apneas in healthy normotensive subjects may suggest an early sign of a mechanism implicated in arterial hypertension in OSAS.

Adult↗

PubMed1998

The effect of a mandibular advancement device on apneas and sleep in patients with obstructive sleep apnea.

OBJECTIVE: To evaluate the effects of a mandibular advancement device on apneas and sleep in mild, moderate, and severe obstructive sleep apnea. DESIGN: Prospective study. SUBJECTS: Forty-four of 47 patients included. INTERVENTION: Individually adjusted mandibular advancement devices. MEASUREMENTS: Polysomnographic sleep recordings for 1 night without the device and 1 night with it, with a median of 1 day and no changes in weight, medication, or sleep position between the recordings. RESULTS: The device reduced the median obstructive apnea-hypopnea index from 11 (range, 7 to 19) to 5 (range, 0 to 17) (p<0.001) in 21 patients with mild sleep apnea, from 27 (range, 20 to 38) to 7 (range, 1 to 19) (p<0.001) in 15 patients with moderate sleep apnea, and from 53 (range, 44 to 66) to 14 (range, 2 to 32) (p<0.05) in 8 patients with severe sleep apnea. The arousal index decreased and the sleep stage patterns improved in all severity groups. Twenty-eight of 44 patients were successfully treated with an obstructive apnea-hypopnea index of below 10 and a subjective reduction in snoring. Nine of 16 patients with treatment failure still reported a reduction in snoring. The success rate correlated inversely to the disease severity (r=-0.41; p<0.01). CONCLUSIONS: A mandibular advancement device reduces apneas and improves sleep quality in patients with obstructive sleep apnea, especially in those with mild and moderate disease. A follow-up sleep recording during treatment is necessary because of the risk of silent obstructive apneas without subjective snoring with the device.

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