Cardiorespiratory Sleep Study Research Articles

Relationship between sleep apnea syndrome, nocturnal hypertension, microalbuminuria and aortic stiffness. A prospective study

Obstructive Sleep apnea (OSA) is prevalent in general population and seems to be a cause of resistant hypertension. To assess the association between OSA and hypertension, aortic stiffness microalbuminuria and left ventricular hypertrophy. 40 patients consecutively referred to a cardio-respiratory sleep study (Autoset Sullivan) to OSA diagnosis. They were submitted to clinical and laboratory evaluation, ambulatory blood pressure monitoring (ABPM, Spacelabs), arterial distensibility study (Complior) and an echocardiography/Doppler study (HP, Sonus). In 33 pts OSA was confirmed (hypo/apnea > 10/h), mean age 52±11, 24 (73%) males, BMI 39±11, office BP 148±18/84, hypo/apnea 40±21. Hypertension was present in 23 pts (70%), 60% on antihypertensive therapy. The majority of pts (88%) with OSA are non-dippers (91% in hypertensive). Although on antihypertensive therapy a large proportion of pts have non-control hypertension (40%) and a more severe OSA. Any correlation was observed between the number of hypo/apnea/h and microalbuminuria, pulse wave velocity, left ventricular mass index, office or ambulatory BP. In hypertensive pts a negative correlation was seen between BP control and the number of hypo/apnea (-0, 63, 0,001). there is a strong link between OSA, hypertension and non-dipper status. Non control hypertension is well correlated with severe obstructive sleep apnea. (See Table)

Estudo cárdio-respiratório do sono domiciliário em crianças. Será exequível?

Childhood obstructive sleep apnea syndrome is a common condition and can result in serious complications. The nocturnal polysomnography remains the gold standard in the diagnosis of this pathology. Given the scarcity of sleep laboratories, namely with paediatric profile, screening techniques have been commonly used. It was our aim to study the yield of the home cardiorespiratory sleep studies carried out in children. Since January of 1999 until June of 2003, 33 home cardiorespiratory sleep studies were performed in children. We studied 31 children (21 male) with a median age of 10.6+/-3.4 years. Five children had craniofacial malformations, 2 neuromuscular diseases and 10 were obese. The signals of nasal flow and saturation were good/acceptable in 67.7% and 96.8% of the cases, respectively. In 2 cases the register was null. Average of apnea-hypopnea index was of 10.7+/-12.3/hour, average saturation of 95.6%+/-3.0 %, minimum saturation of 82.2 %+/-9.2% and dessaturation index of 12.5+/-10.7/hour. Childhood obstructive sleep apnea syndrome was confirmed/suggested in 30 children. The apnea-hypopnea index and the dessaturation index were significantly higher in the group of children with craniofacial malformations and neuromuscular disorders comparatively to children with obesity (26.3 versus 10.5 and 21.5 versus 11.3, respectively) but without statistical significance. In our experience, home cardiorespiratory sleep studies is a diagnostic method easily used in children. This method gives more information comparatively to other screening techniques so that it can evaluate with more accuracy the existence of sleep disordered breathing and may be a possible alternative to polysomnography.

This Month in ANESTHESIOLOGY

This Month in ANESTHESIOLOGY

Practicality of the Sleepstrip in postal screening for obstructive sleep apnoea.

The SleepStrip, a disposable screening device for the detection of obstructive sleep apnoea (OSA), which displays an estimated apnoea-hypopnoea index (AHISS) was posted, with instructions, to 48 patients referred for sleep study for suspected OSA. The patients subsequently underwent a cardiorespiratory sleep study from which the AHIE was derived. Thirty patients (63%) returned the SleepStrip, the device displayed an AHISS in 22 patients (73%), of which 17 (57%) was deemed valid by the device. Twelve of the 30 patients who returned the SleepStrip had an AHIE > or = 20 on the detailed sleep study. Of these, the SleepStrip recording was valid in seven of which only two had an AHISS > or = 20. We concluded that the SleepStrip was not suitable for unsupervised postal screening for OSA.

Sleep-related obstructive disordered breathing in cleft palate patients after palatoplasty.

Sleep-disordered breathing is frequently associated with children presenting congenital midface defects. Because of structural and functional anomalies in the upper airway, children with cleft palate, especially after surgery, may carry a higher risk of developing sleep-disordered breathing. However, the presence of such sleep-disordered breathing in older cleft palate children has not been emphasized. The aim of this comparative overnight cardiorespiratory sleep study was to evaluate cleft palate patients according to sleep-disordered breathing. A group of 43 cleft palate children (17 girls and 26 boys; mean age, 12.1 +/- 3.8 years) was compared with a control group of 20 randomly selected, noncleft children matched for age, sex, and body mass index. None of the patients suffered from manifest sleep-disordered breathing. Cleft palate patients had a statistically significantly higher respiratory disturbance index and snoring index, but no increased apnea index. The data suggest that cleft palate patients having undergone primary closure of the palate demonstrate microsymptoms of nocturnal upper airway obstruction.

Identifying Children at Risk for Complications after Adenotonsillectomy.

Identifying Children at Risk for Complications after Adenotonsillectomy. Wilson et al. (page 313)Hypothesizing that assessment for obstructive sleep apnea (OSAS) might help predict risk for postadenotonsillectomy respiratory complications, Wilson et al. undertook a retrospective chart review of children referred for sleep studies at their institution. Out of 349 children referred for such studies between 1992 and 1998, 163 children had received adenotonsillectomy without concomitant procedures within 6 months of their referral. These were the patients whose medical charts were included in this study.Authors grouped both home and laboratory polysomnography assessments under the general name of cardiorespiratory sleep study, or CRSS. Each patient's CRSS record was analyzed for several variables, and the study reports on the following four parameters: the apnea and hypoapnea index (OAH index), the oxygen saturation (SaO2) nadir, the desaturation index, and the percent time less than 90% saturation (T < 90%). The OAH index was defined as the number of respiratory events (apnea and hypoapnea) per hour of sleep. The severity of sleep-disordered breathing was classified as normal, mild, moderate, or severe depending on the number of episodes (from less than 1 to more than 5). The SaO2nadir was defined as the minimum oxygen saturation occurring during sleep, regardless of its duration.Next, the investigators identified respiratory complications (such as desaturation and airway obstruction) and medical interventions (such as reintubation and positive pressure ventilation) noted in the patients’ postoperative medical records. Children who required interventions were further divided into minor and major intervention groups. There were 34 children (21% of the study population) who had required a medical intervention after respiratory complications. Ten required a major intervention (reintubation, admission to the intensive care unit) and 24 required a minor intervention (such as oxygen therapy beyond the usual period). Fourteen of those requiring a minor intervention (58%) had shown a preoperative SaO2nadir equal to or less than 80%, while 50% of the children requiring a major intervention had shown similar SaO2nadir values.The authors identified age and presence of an associated medical condition as clinical predictors of postoperative respiratory complications. An OAH index of equal to or more than 5 events per hour, and a preoperative nocturnal SaO2nadir of equal to or less than 80% significantly increased the incidence of respiratory complications. Mild, moderate, and severe OSAS were associated with a 6, 14, and 31% incidence of respiratory complications respectively. Determination of nocturnal oxygen saturation may prove not only a cost-effective way to diagnose severe OSAS, but also to predict postoperative risk for complications in children about to undergo adenotonsillectomy.

DIAGNOSING SLEEP APNEA IN DENTAL PATIENTS

Airway dilator or oral appliance therapy has been recommended with behavioral methods as treatment for patients with primary snoring or mild sleep apnea, unless there are patient-specific contraindications. Airway dilator therapy therefore may be a preferred treatment for patients with mild sleepiness and with fewer than 15 episodes of sleep disordered breathing per hour. The dentist's main diagnostic concern is to separate those patients with moderate or severe sleep apnea, who should be referred to a medical specialist for treatment, from those patients with primary snoring or mild sleep apnea, whom the dentist may treat primarily. Diagnostic tests including clinical predictions formulas, polysomnography, cardiorespiratory sleep studies, and oximetry will be discussed in this review.

Validierung einer 7kanaligen ambulanten Polygraphieeinheit

For some time, the ambulatory diagnosis of respiratory disturbances during sleep has included the use of seven-channel recording units. One of these systems is the POLY-MESAM unit (MAP, Germany). The aim of the present study was to validate the POLY-MESAM system by simultaneously performing 12-channel polysomnography. Forty-nine patients (45 males and 4 females) with different severities of obstructive sleep-related breathing disorders were included. Obstructive sleep apnea was diagnosed, when an apnea-hypopnea index (AHI) > 15 was found by polysomnography. The sensitivity and specificity for POLY-MESAM were calculated on the basis of the polysomnographic AHI. The sensitivity of POLY-MESAM for detecting patients with an AHI > 15 was 86.4% and the specificity was 100%. The POLY-MESAM system was easy to use. The sensitivity and specificity for the MESAM4 unit were 92% and 97% respectively, which was similar to POLY-MESAM. Additionally, POLY-MESAM provided the possibility for distinguishing the different kinds of apneas. Thus, POLY-MESAM was considered to be a useful development of the previous MESAM4 unit. In some cases, use of the POLY-MESAM unit resulted in underestimation of the AHI. POLY-MESAM produced false-negative results in patients with mild to moderate OSA. This finding was reflected in the relatively poorer sensitivity of the method (86.4%). Cardiorespiratory sleep studies (as possible with POLY-MESAM) are best limited to patients for whom the diagnosis of OSA is highly probable or as a follow-up tool in selected circumstances.

Sleep‐disordered breathing in patients with myelomeningocele: the missed diagnosis

Moderate to severe sleep‐disordered breathing (SDB) was identified in 20% (17 of 83) of children with spina bifida/myelomeningocele (SB/MM) at the Montreal Children's Hospital. The prevalence of SDB in patients with SB/MM elsewhere has not been determined. To establish current practices for identifying SDB in patients with SB/MM, questionnaires were sent to the coordinators of the 212 spina‐bifida clinics in Canada and in the United States. Eighty‐six (41%) questionnaires were returned, representing data on 13 349 patients. Although 67% of the responding centers reported availability of cardiorespiratory sleep studies, only 996 (7.5%) patients with SB/MM had been tested and only 418 (3.1%) patients had been diagnosed with SDB. Across clinics, the prevalence of SDB was directly related to the frequency of testing. Of 380 deaths over the past 10 years, SDB and sudden unexplained death during sleep were identified as the cause of death in 49 (12.8%) and 34 (8.9%) patients, respectively. Moderate to severe SDB may not have been identified in a significant number of patients with SB/MM because they have not been tested.

Sleep-disordered breathing in patients with myelomeningocele: the missed diagnosis.

Moderate to severe sleep-disordered breathing (SDB) was identified in 20% (17 of 83) of children with spina bifida/myelomeningocele (SB/MM) at the Montreal Children's Hospital. The prevalence of SDB in patients with SB/MM elsewhere has not been determined. To establish current practices for identifying SDB in patients with SB/MM, questionnaires were sent to the coordinators of the 212 spina-bifida clinics in Canada and in the United States. Eighty-six (41%) questionnaires were returned, representing data on 13 349 patients. Although 67% of the responding centers reported availability of cardiorespiratory sleep studies, only 996 (7.5%) patients with SB/MM had been tested and only 418 (3.1%) patients had been diagnosed with SDB. Across clinics, the prevalence of SDB was directly related to the frequency of testing. Of 380 deaths over the past 10 years, SDB and sudden unexplained death during sleep were identified as the cause of death in 49 (12.8%) and 34 (8.9%) patients, respectively. Moderate to severe SDB may not have been identified in a significant number of patients with SB/MM because they have not been tested.

Breathing patterns in children with craniofacial dysostosis and hindbrain herniation.

In the past few years, hindbrain herniation has become recognized as a frequent feature of the child with syndromic craniofacial dysostosis. The clinical significance of hindbrain herniation in these disorders is unclear. Abnormalities of respiratory control have frequently been reported. The aim of the present study was to document the incidence of obstructive and central respiratory abnormalities during sleep in craniofacial syndromes with hindbrain herniation. We performed cardiorespiratory sleep studies during unsedated night-time sleep in a group of 13 children. Hindbrain herniation was confirmed by magnetic resonance imaging (MRI) and ranged 1.5-26.9 mm below the cranial base. Sleep studies revealed central respiratory pauses associated with important reduction of the arterial oxygen saturation (Sa,O2) in only two of 13 cases (minimum Sa,O2 86% and 87%). In contrast 10 of 13 children had some degree of upper airway obstruction (four mild, three moderate and three severe). Of the remaining three children, two had previous long-term tracheostomies. Changes in the breathing pattern were proportional to the severity of the obstruction and comprised increased respiratory efforts and arterial oxygen desaturation. Infrequent mixed apnoeas were observed in five patients, and their severity reflected the severity of the obstructive component. In conclusion, obstruction of the upper airways was the predominant sleep-related respiratory problem in this group of patients. Hindbrain herniation was not associated with a high incidence of central sleep apnoea.

Upper airway obstruction and raised intracranial pressure in children with craniosynostosis.

In children with craniosynostosis, raised intracranial pressure (ICP) and upper airway obstruction (UAO) are both common features. However, potential interactions between UAO and ICP during sleep are poorly understood. The aim of the present study was to compare the levels of ICP during sleep between a group of patients with syndromic craniosynostosis (with facial involvement and consequent UAO) and a group of control patients with isolated unicoronal synostosis (with no facial involvement and normal upper airways). Polygraphic cardiorespiratory sleep studies with continuous monitoring of ICP were performed during unsedated sleep in 13 children with syndromic craniosynostosis and 7 control patients with isolated unicoronal synostosis only. In the syndromic group, UAO was present in 11 out of 13 patients, with 8 out of 13 having frank obstructive sleep apnoea. In contrast, none of the control patients showed signs of UAO during sleep. There was no evidence of central apnoeas in any of the patients studied. Clinical histories taken from parents tended to underestimate the severity of the respiratory problems. Elevated ICP was seen in 10 of the 13 syndromic patients, with borderline raised ICP in the remaining three cases. In contrast, raised ICP was seen in only 3 of the 7 control patients, with borderline raised levels in 2 of the 7. For both patient groups, ICP was higher during active sleep compared to quiet sleep. Multiple regression analysis showed that ICP during active sleep was dependent upon disease severity (unicoronal/ multiple synostosis) and to the baseline ICP level during quiet sleep. Both raised ICP and airway obstruction were more apparent during active sleep. There was a significant correlation between severity of UAO and increased ICP in active sleep. We conclude that obstructive respiratory problems are frequent in the syndromic patients, and can be severe in a large proportion of cases; intracranial hypertension is also frequent in this group. Further studies are required to investigate the possibility of a causal relationship between upper airway obstruction and raised intracranial pressure.

Cardiorespiratory Sleep Studies for Children Can Often Be Performed in the Home

We developed a portable recording system, suitable for unattended use in a patient's home, that quantitates the essential diagnostic elements of pediatric obstructive sleep apnea syndrome (OSAS): obstructive, mixed and central apneas and hyponeas; hemoglobin saturation, sleep vs. wakefulness; body and head positions; snoring: and sleep disturbance. The present paper reviews validation studies and summarizes two recent studies that demonstrate the unique advantages of performing clinical and research cardiorespiratory sleep studies in the child's home. Development of inexpensive, portable records that integrate audiovisual and physiologic information will make such home recordings more widely available.