Apnea Plus Hypopnea Index Research Articles

Blood count values and ratios for predicting sleep apnea in obese children

ObjectivesTo detect whether the mean platelet volume (MPV), neutrophil-to-lymphocyte ratio (NLR), and platelet-to-lymphocyte ratio (PLR) are contributing factors in the diagnosis and severity of sleep apnea in obese children. IntroductionObesity is a public health problem, and its prevalence increases daily. Although PSG is the gold standard test in the investigation of sleep apnea, the application of this test requires equipment, personnel, time, and cost. There is no simple laboratory test for diagnosing and determining the severity of sleep apnea. Recently, MPV, NLR, and PLR, known as the inflammatory markers in CBC test parameters, have been investigated in some studies. We aim to investigate whether these parameters could provide a method for diagnosing and determining the severity of OSAS in obese children. MethodsClinical records of 180 patients were evaluated. All subjects had venous blood samples collected from the antecubital vein in the morning, after an overnight fasting, one day before PSG. Hemoglobin, RDW, MPV, PLT, platelet distribution width (PDW), and WBC count were measured. After anthropometric and laboratory analysis, 127 obese children were assessed for sleep study. Eighty-three patients who met the required polysomnographic criteria were divided into three groups as follows: group A [non-OSAS, apnea-plus-hypopnea index (AHI) < 1], groupB (1 ≤ AHI < 5), and groupC (AHI ≥ 5). ResultsTotal recording time, total sleep time, sleep efficiency, REM, and NREM sleep stage latency values were not statistically significant among groups. However, the number of awakenings, AHI, oxygen desaturation events, mean oxygen saturation, lowest oxygen saturation, average desaturation, and snoring time values had significant difference among the groups. There was no statistically significant difference among the groups in terms of WBC, Hemoglobin, platelets, PDW, neutrophil, and lymphocyte values. However, RDW values showed a statistically significant difference between groups A and C. Although there was no statistically significant difference of MPV values among groups, NLR and PLR values were statistically significant between groups A and C. ConclusionAccording to our study, NLR, PLR, and RDW were found to be significantly higher in children whose AHI was ≥5 than in children from the other groups. However, no correlation was found between MPV levels and OSAS in children.

Relation of Central Fat Mass to Obstructive Sleep Apnea in the Elderly

Obesity is a recognized risk factor for obstructive sleep apnea syndrome (OSAS). We evaluated whether total trunk and central fat mass (CFM) is associated with OSAS in elderly subjects. Cross-sectional. Body composition assessment by dual-energy X-ray absorbsiometry (DEXA). 749 volunteers aged 67.2 ± 0.8 years (59.4% women). All participants underwent evaluation of their body composition by DEXA in parallel with clinical and polygraphic assessments. The presence of OSAS was defined by an apnea plus hypopnea index (AHI) ≥ 15. A total of 44.8% of the population had an AHI < 15, and 55.2% presented OSAS. OSAS subjects were more frequently overweight and had a higher total trunk fat mass and central fat mass (CFM). Correlation analyses revealed that body mass index (r = 0.27, P < 0.001), neck circumference (r = 0.35, P < 0.001), and CFM (r = 0.23, P < 0.001) were significantly related to AHI. Logistic regression analysis indicated that in mild OSAS cases (> 15AHI < 30), BMI (OR: 1.10; 95% CI: 1.03-1.18; P = 0.008), and male gender (OR: 1.49; 95% CI: 1.05-2.12, P = 0.03) were key factors explaining an AHI between 15 and 30. In severe cases (AHI > 30), male gender (OR: 3.65; 95% CI: 2.40-5.55; P < 0.001) and CFM (OR: 1.10; 95% CI: 1.03-1.19; P = 0.009) were significant independent predictors of OSAS. NCT 00759304 and NCT 00766584. Although central fat mass plays a role in the occurrence of severe OSAS in men older than 65 years of age, its low discriminative sensitivity in mild OSAS cases does not warrant systematic use of DEXA for the diagnosis of OSAS.

Use of high-frequency peak in spectral analysis of heart rate increment to improve screening of obstructive sleep apnoea

Several studies have correlated the ratio of the very low frequency power spectral density of heart rate increment (%VLFI) with obstructive sleep apnoea syndrome (OSAS). However, patients with impaired heart rate variability may exhibit large variations of heart rate increment (HRI) spectral pattern and alter the screening accuracy of the method. To overcome this limitation, the present study uses the high-frequency increment (HFI) peak in the HRI spectrum, which corresponds to the respiratory influence on RR variations over the frequency range 0.2 to 0.4 Hz. We evaluated 288 consecutive patients referred for snoring, observed nocturnal breathing cessation and/or daytime sleepiness. Patients were classified as OSAS if their apnoea plus hypopnoea index (AHI) during polysomnography exceeded 15 events per hour. Synchronized electrocardiogram Holter monitoring allowed HRI analysis. Using a %VLFI threshold >2.4% for identifying the presence of OSAS, sensitivity for OSAS was 74.9%, specificity 51%, positive predictive value 54.9% and negative predictive value 71.7% (33 false negative subjects). Using threshold for %VLFI >2.4% and HFI peak position >0.4 Hz, negative predictive value increased to 78.2% while maintaining specificity at 50.6%. Among 11 subjects with %VLFI <2.4% and HFI peak >0.4 Hz, nine demonstrated moderate to severe OSAS (AHI >30). HFI represents a minimal physiological criterion for applying %VLFI by ensuring that heart rate variations are band frequency limited.

Hypertension prevalence in obstructive sleep apnoea and sex: a population-based case–control study

Obstructive sleep apnoea (OSA) is a recognised risk factor for hypertension (HT). The current authors investigated confounders of this association in a sex-balanced community-based sample of patients with HT (n=161) from the Skaraborg Hypertension and Diabetes Project (n=1,149) and normotensive controls (n=183) from an age and sex stratified community-based population sample (n=1,109). All participants underwent ambulatory home polysomnography. Severe OSA (apnoea-plus-hypopnoea index (AHI)>or=30 events.h-1) was found in 47 and 25% of hypertensive and normotensive males, respectively. The corresponding numbers in females were 26 and 24%, respectively. The odds ratio (OR) for HT increased across AHI tertiles from 1.0 to 2.1 (95% confidence interval: 0.9-4.5) and 1.0 to 3.7 (95% CI: 1.7-8.2) in males, but not in females where the OR increased from 1.0 to 1.8 (95% CI: 0.8-3.9) and 1.0 to 1.6 (95% CI: 0.7-3.5). Regression analysis correcting for age, body mass index (or waist-hip ratio) and smoking did not eliminate the association between OSA and HT in males. The present data suggest that obstructive sleep apnoea is highly prevalent in both the general population and in patients with known hypertension. The contribution of obstructive sleep apnoea to hypertension risk may be sex dependent and higher in males than in females.

Uvulopalatopharyngoplasty for obstructive sleep-related breathing disorders: one-year follow up.

The effectiveness of uvulopalatopharyngoplasty was evaluated in 28 patients (25 men and three women; mean age 47.6 years) with obstructive sleep apnea by comparing preoperative daytime polysomnography with those carried out 6 months and 1 year postoperatively. The mean apnea plus hypopnea index (AHI) in the supine position decreased from 51.0/h to 23.0/h 6 months postoperatively and 57.1% of patients showed a 50% or more reduction of AHI. By changing the sleep position from supine to lateral, 71.4% of the 28 patients indicated a 50% or more reduction in AHI before surgery, which increased to 92.3% of 26 patients 6 months postoperatively. The positive results of uvulopalatopharyngoplasty were maintained at least until 1 year after surgery.

Tracing air flow and diagnosing hypopnoeas in normalsubjects

Hypopnoea is a type of sleep-related breathing disorder (SRBD), and the apnoeaplus hypopnoea index (AHI) is usually computed to diagnose this condition. Weintroduce a new method to diagnose flow with internal thermistors located onthe same sensors as we use to diagnose obstructive segments in patients withsleep-related breathing disorders. The aim of this study is to investigatewhether internal thermistors are reliable for diagnosis of hypopnoeas. Fifteenvolunteers participated in a prospective comparative study in healthy subjectswithout SRBD. We simultaneously measured minute ventilation by apneumotachograph and indirectly air flow by internal thermistors in awakesubjects was manually analysed from both the pneumotachograph and the internalthermistors. We found a close agreement between the different methods forpercentage reduction in air flow both for the hypopnoea and the apnoea data.The mean difference between the percentage reduction in flow from normalbreathing to hypopnoea measured by the pneumotachograph and the internalthermistors lying supine was 3.8% (SD 7.4). In the lateral position thecorresponding figures were 1.0% and 4.6. This study in awake, normal subjectsindicates that internal thermistors are as reliable as the pneumotachograph indiagnosing hypopnoeas and we believe that the reliability of this monitoringmethod is adequate for clinical use.

Pharyngeal critical pressure in patients with obstructive sleep apnea syndrome. Clinical implications.

Current evidence suggests that patients with obstructive sleep apnea (OSA) may have greater pharyngeal critical pressure (Pcrit), which reflects the increase in upper airway collapsibility. The contribution of Pcrit to the severity of OSA and to the efficacious continuous positive pressure (nCPAPeff) therapy has never been extensively described and no data are available about the interaction of Pcrit, age, and anthropometric variables. To determine the relationship between Pcrit, severity of the disease, nCPAPeff, and anthropometric variables we measured Pcrit in a group of 106 patients with OSA. Pharyngeal critical pressure was derived from the relationship between maximal inspiratory flow and nasal pressure, Pcrit representing the extrapolated pressure at zero flow. Upper airway resistance (Rus) was determined as the reciprocal of the slope (DeltaPn/DeltaVImax cm H2O/L/s) in the regression equation. In a subgroup of 68 patients, during the diagnostic night, we measured as indices of respiratory effort, the maximal inspiratory esophageal pressure (Pes) at the end of apnea (Pesmax), the overall increase from the minimum to the maximum (DeltaPes), and the rate of increase of Pes during apnea (RPes). As a group, the mean Pcrit was 2.09 +/- 0.1 cm H2O (range, 0 to 4.5) and the mean Rus was 11.1 +/- 0.5 cm H2O/L/s. Although men have greater Pcrit, pharyngeal collapsibility was influenced neither by neck size nor by body mass index (BMI). Although there was a significant relationship between Pcrit and apnea plus hypopnea index (AHI) (r = 0.23, p = 0.02), neck circumference was the stronger predictor of apnea frequency, with Pcrit contributing only to the 3% of the variance. In the group of patients as a whole, a model including AHI, BMI, Rus, and Pcrit explained the 36% of the variance in nCPAPeff, with a greater contribution of AHI, Pcrit accounting for only 3% of the variation. In patients for whom the measure of respiratory effort was obtained, 42% of the variance in nCPAPeff was explained by RPes (33%) and BMI. From these results we conclude that Pcrit alone does not yield a diagnostically accurate estimation of OSA severity and nCPAPeff. Although individual collapsibility may predispose to pharyngeal collapse, upper airway occlusion may require the combination of several factors, including obesity, upper airway structure, and abnormalities in muscle control.

An unattended device for sleep-related breathing disorders: validation study in suspected obstructive sleep apnoea syndrome.

Portable devices for the diagnosis of obstructive sleep apnoea (OSA) are considered to be an acceptable alternative to polysomnography (PSG), but their validation is essential. The aim of our study was to validate a device specifically designed for OSA diagnosis. Twenty nine suspected OSA patients were studied with simultaneous nocturnal PSG and an unattended recording device (MicroDigitrapper-S) (M-S). The device measured body position, snoring sound, oronasal flow, thoracic and abdominal effort, heart rate and percentage arterial oxygen saturation (Sa,O2%). We compared the apnoea plus hypopnoea index (AHI) and Sa,O2% results of PSG with that of the system's automatic analysis (M-SA). We also performed a semiautomatic analysis (M-SS) with visual editing of the raw data. Results at different AHI cut-off levels were analysed to obtain an indication of accuracy in diagnosis and severity. Both M-SA and M-SS showed a sensitivity and specificity of 100% at the cut-off level of AHI > 10. When increasing the cut-off levels, M-SA sensitivity decreased (55% for AHI > 40), while specificity remained high (95%). This was improved to a clinically acceptable level of agreement by M-SS analysis (sensitivity 91% and specificity 94%). In conclusion, the MicroDigitrapper-S device showed a good sensitivity and specificity for the diagnosis of OSA. However, the device could not predict the severity of OSA precisely enough. In severe cases (apnoea plus hypopnoea index > 40), semi-automatic scoring was necessary to obtain a more accurate detection of the severity of the disease.

Predictors of outcome for uvulopalatopharyngoplasty.

The objective of this study was to assess the value of preoperative fiberoptic nasopharyngoscopy with the Müller maneuver (FNMM) and cephalometric radiography in predicting response to uvulopalatopharyngoplasty (UPPP) in patients with obstructive sleep apnea syndrome. Fifty-three such patients having significant obstruction at the soft palatal level and variable degrees of obstruction at the base-of-tongue level underwent both diagnostic procedures before UPPP. Outcome was assessed by the apnea-plus-hypopnea index (AHI) as determined by polysomnography, which was performed before and after surgery. As a group, patients exhibited a significant 10-point reduction in AHI (46.5 to 36.7). However, 17 (32.1%) were judged to be responders as defined by a reduction of the AHI by an increment of 50% or greater with respect to baseline. Of all the cephalometric variables assessed, soft palate length was the only one that differed between responders and nonresponders (45.5 mm versus 42.6 mm, respectively). However, this difference only approached significance (P = .067). Similarly, FNMM results did not discriminate between responders and nonresponders. These results indicate that preoperative cephalometric radiography and FNMM cannot be reliably used to enhance surgical success.

Computerized detection of respiratory events during sleep from rapid increases in oxyhemoglobin saturation

A computerized search for rapid resaturation (RES)--defined as increases in oxyhemoglobin saturation (SaO2) of 3% or more within 10 s--was used to detect apneas and hypopneas during sleep by the episodes of compensatory hyperventilation following them. Results were compared to those from computerized search for desaturations (DESAT)--defined as decreases in SaO2 of 4% or more within 40 s--and to simultaneous polysomnography. We studied 30 patients with obstructive sleep apnea (OSA) with an apnea plus hypopnea index (AHI) of 30.8 +/- 6.9 (median +/- SEM) and 23 habitual snorers (HSN) with an AHI of 7 +/- 1.5. Manual scoring of polysomnography revealed 7965 respiratory events (6192 apneas, 1773 hypopneas) in OSA patients and 940 events (411 apneas, 529 hypopneas) in the HSN group. In OSA patients, the computer found 96% of events by searching for RES and 87% by searching for DESAT. The percentage of computer-found events in OSA classified as true positive was 91% for RES and 97% for DESAT. In the HSN group, 83% of polysomnographically scored events were found by RES and 55% by DESAT, with 72% of RES and 84% of DESAT being true positive. The correlation of the number of computer-found RES with the number of events from polysomnography was better in OSA (r = 0.862, p less than 0.0001) than in HSN (r = 0.722, p less than 0.001). The same was true for DESAT (OSA: r = 0.896, p less than 0.0001; HSN: r = 0.637, p less than 0.01). In conclusion, computer-found rapid resaturations are more sensitive than desaturations for the detection of respiratory events during sleep from oximetry.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantification of sleep disordered breathing by computerized analysis of oximetry, heart rate and snoring

Intermittent snoring and cyclic oscillations of heart rate and oxyhaemoglobin saturation (Sao2) are characteristic features of the obstructive sleep apnoea syndrome (OSAS). Thus, overnight recordings of laryngeal sounds and heart rate by a portable device (MESAM) and of Sao2 by oximetry are applicable to screen outpatients for the presence of OSAS. Computerized analysis for time intervals of constant heart rate and intervals between snoring sounds is used by MESAM to quantify respiratory disturbances during sleep. Rapid increases in Sao2 during the postapnoeic hyperventilation period together with the number of desaturations are used by a new software for quantitative analysis of oximetry. To elucidate reliability of results from automatically scored MESAM and oximetry recordings, we compared the four computer calculated respiratory disturbance indices from heart rate (RDIH), snoring (RDIS), resaturations (RDIR) and desaturations (RDID) with the apnoea plus hypopnoea index (AHI) from simultaneously performed polysomnography. The study population consisted of 53 snorers with an AHI of 19.0 +/- 2.6 (median +/- SEM; range 0.7-87.8). Whereas both RDI's from MESAM correlated rather weakly with the AHI from polysomnography (RDIH: r = 0.32, p less than 0.05; RDIS: r = 0.33, p less than 0.05), this correlation was much better for the RDI's from oximetry (RDIR: r = 0.951, RDID: r = 0.93; p much less than 0.0001). Accepting a plus/minus 30 percent difference from the AHI, the RDIR classified 77% of patients correctly, the RDID 62%, the RDIS 32% and the RDIH 23%. In conclusion, results from computerized analysis of oximetry for desaturations and rapid resaturations correlate more closely with polysomnography than those from automatic scoring of MESAM recordings.

Nasal and Oral Flow-Volume Loops in Normal Subjects and Patients with Obstructive Sleep Apnea

Because flow-volume loops (FVLs) are clinically useful in evaluating upper airway (UA) obstruction and the fact that patency of the nasopharyngeal ventilatory pathway is important to the prevention of obstructive sleep apnea (OSA), the present study examined the role of nasal compared with oral FVLs in evaluating patients with OSA. Fourteen obese male patients 56 +/- 3 yr of age with a mean apnea plus hypopnea index (AHI) of 51 +/- 9/h were studied along with 14 nonobese, healthy, age- and sex-matched control subjects whose mean AHI was 6 +/- 1/h. Nasal and oral FVLs obtained in the normal subjects indicated the nose behaved like a variable resistor, with flow limitation during inspiration but not during expiration. In the patient group, flow limitation was observed during expiration as well as inspiration indicating nondistensibility of the nasopharyngeal ventilatory pathway in the patients compared to the control subjects. A change in body position from upright to supine in the OSA group was associated with small reductions in expiratory but not inspiratory flow rates. The area under the nasal supine flow-volume loop (FVLANaSup) was found to be highly correlated with awake resting PaO2 (r = 0.80) and PaCO2 (r = -0.83) in the patient group. In addition, multiple linear regression analysis revealed that PaO2 and the area under the nasal FVLs independently contributed to the prediction of AHI with a multiple R of 0.89. These results suggest that limitations to ventilation via the nasopharynx may significantly influence both gas exchange and the frequency of sleep-disordered breathing in patients with OSA.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term Compliance with Nasal Continuous Positive Airway Pressure Therapy of Obstructive Sleep Apnea

In an attempt to identify predictors of long-term compliance with nasal continuous positive airway pressure (CPAP), we reviewed the records of 125 patients with obstructive sleep apnea (OSA) referred to our center for nasal CPAP trials. Severity of sleep apnea, sleep staging, daytime hypersomnolence, effectiveness of nasal CPAP, previous palatal surgery, and adverse reactions were compared in compliant and noncompliant patients. Nineteen patients did not tolerate a nasal CPAP trial in the laboratory or refused home nasal CPAP therapy. Ten patients were unavailable for follow-up. Of the remaining 96 patients, 23 (24 percent) had discontinued therapy, while 73 (76 percent) were still using nasal CPAP at 14.5 +/- 10.7 months (mean +/- SD). There were no statistically significant differences between the compliant and noncompliant patients in baseline apnea plus hypopnea index (AHI), baseline sleep staging, AHI while receiving nasal CPAP, sleep staging while receiving nasal CPAP, or frequency of adverse reactions during therapy. Severe daytime sleepiness was present in 65 of the 73 compliant patients and in 12 of the 23 noncompliant patients (p less than 0.05). Ten of 43 in the compliant group had previous palatal surgery compared with ten of 23 noncompliant patients (p less than 0.05). Our data confirm earlier observations in smaller samples that compliant and noncompliant patients have equally severe sleep apnea and good initial responses to nasal CPAP. Long-term compliance with nasal CPAP may be associated with the severity of daytime hypersomnolence on presentation. Previous palatal surgery was more frequent in patients who did not tolerate long-term nasal CPAP therapy.

Evaluation of the Upper Airway by Computerized Tomography in Patients Undergoing Uvulopalatopharyngoplasty for Obstructive Sleep Apnea

This study utilized computerized tomography (CT) to evaluate the effects of uvulopalatopharyngoplasty (UPPP) on upper airway (UA) dimensions. The objectives were to determine whether CT scan results would be useful in identifying UA characteristics predictive of a good surgical result as well as elucidating reasons for failure of this operative procedure. Twenty-three male patients with obstructive sleep apnea (OSA) had CT scans and polysomnography performed before and after UPPP. Preoperatively, the apnea plus hypopnea index (AHI) was 64 +/- 6 per hour and the minimal UA cross-sectional area (Amin) was located at 10 and 20 mm below the level of the hard palate in 87% (20 of 23) of the patients. Uvulopalatopharyngoplasty more than doubled UA cross-sectional areas at these two proximal levels. In contrast, the hypopharyngeal segment located 50 to 70 mm below the hard palate decreased in cross-sectional area by 23 to 25% after surgery. Eight patients (35%) had a good response to UPPP based on a greater than 50% decrease in AHI. Preoperatively, seven of these eight patients had Amin located 20 mm below the hard palate. Uvulopalatopharyngoplasty increased Amin and oropharyngeal cross-sectional areas to a greater extent in the good than in the poor responders. A poor response to UPPP was associated with preoperative Amin greater than 1 cm2, location at site other than 20 mm below the hard palate, and postoperative narrowing at the level of the hard palate. Patients with Amin less than 1.0 cm2 located 20 mm below the hard palate (lower velopharynx) were most likely to obtain a favorable result with surgery.

Determinants of Hypercapnia in Occlusive Sleep Apnea Syndrome

To assess the relative contributions of age, gender, obesity, pulmonary function, and the severity of sleep-induced respiratory abnormalities to the development of alveolar hypoventilation in patients with occlusive sleep apnea syndrome, prospective data from III patients with occlusive sleep apnea were analyzed by stepwise logistic and multiple regression techniques. The significant variables in a logistic regression model predicting the presence of hypercapnia were daytime arterial oxygen pressure (PaO2; p less than 0.0001) and gender (p less than 0.04), the latter reflecting the higher number of hypercapnic women in our patient population. Multiple regression analysis performed in the hypercapnic group to study the determinants of the severity of elevation of arterial carbon dioxide tension (PaCO2) revealed significant contribution from the PaO2, the apnea-plus-hypopnea index (AHI), and the percent predicted forced vital capacity (r2 = 0.56; p less than 0.0001), whereas in the normocapnic patients, PaCO2 related to PaO2 only. These results suggest that daytime hypoxemia, mechanical impairment of the respiratory system due to obesity or obstructive airway disease (or both), and the severity of sleep-induced respiratory abnormalities as assessed by AHI contribute to the severity of carbon dioxide retention in patients with occlusive sleep apnea in a multifactorial fashion.

Relationship between Pulmonary Function and Sleep-Induced Respiratory Abnormalities

The relationships between pulmonary function and sleep-induced respiratory events were studied in 34 consecutive male patients with suspected sleep apnea syndrome. In view of the effects of obstructive airway disease on pulmonary volume and airway resistance (Raw), patients were divided into two groups, those with and those without obstructive airway disease. Percent predicted functional residual capacity (FRC) correlated significantly with the apnea-plus-hypopnea index (AHI) in patients with and without obstructive airway disease (r = -0.62 and p less than 0.01; and r = -0.57 and p less than 0.01, respectively) whereas percent predicted total lung capacity had a significant relationship with AHI only in patients with obstructive airway disease (r = -0.80; p less than 0.001). In patients without such disease, a significant correlation between inspiratory airway conductance (Gaw) and AHI (r = -0.47; p less than 0.05) was also present, while percent predicted FRC and Gaw did not correlate with normalized weight. These findings suggest that decreased pulmonary volume and increased Raw contribute to the severity of sleep-induced respiratory abnormalities in patients with sleep apnea syndrome regardless of the degree of obesity.