Predictive equations for CPAP titration in OSAS patients.

BACKGROUND: Continuous positive airway pressure (CPAP) is the elective treatment of obstructive sleep apnea. The therapeutic level of CPAP is generally established by manual titration or an auto CPAP device, but an alternative way involves the use of predictive formulas. The aim of the present study was to test the difference between mathematical equations and CPAP or auto CPAP in terms of therapeutic pressure. METHODS: A retrospective analysis of 197 subjects with a diagnosis of obstructive sleep apnea needing a CPAP treatment was performed. The patients were divided into two groups: the first one included patients who had received CPAP after manual titration and the second one included patients who had received auto CPAP titration. The therapeutic CPAP pressure was then compared to the pressure calculated by three different equations: Eq. A by Stradling, Eq. B by Sériès, and Eq. C by Hoffstein. RESULTS: One hundred ninety-seven patients were included in the study, 110 were titrated by auto CPAP and 87 by manual titration. There was a positive correlation between the pressure defined by the three equations and both titration methods, but each equation usually gave a higher pressure with patients needing CPAP <8 and lower for patients needing CPAP >11. Equation C normally gave a lower result than the other two equations. CONCLUSIONS: Manual or auto CPAP titration remains the best way to define the appropriate CPAP. However, predictive formulas can be useful if used with caution and always after verifying the real efficacy, particularly for patients needing higher pressure.

Association between low sniff nasal-inspiratory pressure (SNIP) and sleep disordered breathing in amyotrophic lateral sclerosis: Preliminary results.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that rapidly involves the respiratory system, leading to persistent respiratory insufficiency. Neuromuscular respiratory weakness is also responsible for sleep disordered breathing (SDB), which occurs at an early stage of ALS. Maximal sniff nasal-inspiratory pressure (SNIP) is a sensitive test to early disclose respiratory muscle decline. The aim of this study was to evaluate the role of the SNIP test, compared to FVC, as a marker of SDB in ALS. We studied 31 (18 males) patients with ALS, who were divided into two groups according to the SNIP test value. Ten patients who showed a SNIP value higher than 60 cmH(2)O were considered as group 1. Twenty-one patients exhibited a SNIP lower than 60 cmH(2)O and were included in group 2. Both groups of patients were also investigated with nocturnal sleep study. A linear correlation between lower SNIP value and reduced nocturnal SaO(2) in patients with a SNIP value less than 60 cmH(2)O (n = 21; r = 0.449; p = 0.04) was found. A negative correlation between SNIP and time spent in SaO(2) below 90% (TST90) (n = 21; r = -0.584; p = 0.0054), and between SNIP and oxyhaemoglobin desaturation index (ODI, events/hour) (n = 21; r = -0.458; p = 0.0368) was also established in all the patients of group 2, while, in this group, FVC did not correlate with any nocturnal parameter observed. A positive correlation between SNIP and PaO(2) at baseline of the entire population of patients (n = 31; r = 0.614; p < 0.001) was also seen. In conclusion, the results of this preliminary study show that SNIP < 60 cmH(2)O might be considered an early predictor of SDB in ALS.

Exhaled and arterial levels of endothelin-1 are increased and correlate with pulmonary systolic pressure in COPD with pulmonary hypertension.

BACKGROUND: Endothelin-1 (ET-1) and Nitric Oxide (NO) are crucial mediators for establishing pulmonary artery hypertension (PAH). We tested the hypothesis that their imbalance might also occur in COPD patients with PAH. METHODS: The aims of the study were to measure exhaled breath condensate (EBC) and circulating levels of ET-1, as well as exhaled NO (FENO) levels by, respectively, a specific enzyme immunoassay kit, and by chemiluminescence analysis in 3 groups of subjects: COPD with PAH (12), COPD only (36), and healthy individuals (15). In order to evaluate pulmonary-artery systolic pressure (PaPs), all COPD patients underwent Echo-Doppler assessment. RESULTS: Significantly increased exhaled and circulating levels of ET-1 were found in COPD with PAH compared to both COPD (p < 0.0001) only, and healthy controls (p < 0.0001). In COPD with PAH, linear regression analysis showed good correlation between ET-1 in EBC and PaPs (r = 0.621; p = 0.031), and between arterial levels of ET-1 and PaPs (r = 0.648; p = 0.022), while arterial levels of ET-1 inversely correlated with FEV1%, (r = -0.59, p = 0.043), and PaPs negatively correlated to PaO2 (r = -0.618; p = 0.032). Significantly reduced levels of FENO were found in COPD associated with PAH, compared to COPD only (22.92 +/- 11.38 vs.35.07 +/- 17.53 ppb; p = 0.03). Thus, we observed an imbalanced output in the breath between ET-1 and NO, as expression of pulmonary endothelium and epithelium impairment, in COPD with PAH compared to COPD only. Whether this imbalance is an early cause or result of PAH due to COPD is still unknown and deserves further investigations.

Relationship between energy expenditure, physical activity and weight loss during CPAP treatment in obese OSA subjects.

BACKGROUND: Increased energy expenditure (EE) has been reported in patients with obstructive sleep apnea (OSA). It has been postulated that CPAP treatment may induce weight reduction in obese patients, even if it has not been confirmed by recent studies. In the present study we investigated the effect of OSA on EE and the effect of CPAP on body weight and physical activity. METHODS: One hundred and seven obese OSA patients and 25 healthy obese volunteers, as control group, matched for age, sex and BMI, were enrolled. The following evaluation was performed only in OSA patients after 6 months of CPAP treatment. RESULTS: Baseline total EE was similar in the two groups, but OSA patients showed higher EE during the night, while control group during daytime. In patients, EE correlates with OSA severity, degree of daytime sleepiness or obesity. At follow-up evaluation, BMI and total EE were unchanged. However, daytime EE increased (1066 ± 131.5 vs 1104 ± 133 Kcal/die, p < 0.001, respectively) and night EE decreased (694 ± 69 vs 595 ± 73, p < 0.0001, respectively). Statistically significant changes in BMI, sleepiness scale, blood gases and EE were found only in patients who were compliant to CPAP. CONCLUSIONS: Obese OSA patients showed an increased night EE that was normalized only in those patients compliant to CPAP. Body weight and daily physical activity did not change in statistically significant way.

Efficacy of Bilevel-auto Treatment in Patients with Obstructive Sleep Apnea Not Responsive to or Intolerant of Continuous Positive Airway Pressure Ventilation.

BACKGROUND: Ventilation with continuous positive airway pressure (CPAP) is the gold standard therapy for obstructive sleep apnea (OSA). However, it was recently suggested that a novel mode of ventilation, Bilevel-auto, could be equally effective in treating patients unable to tolerate CPAP. The aim of this study was to investigate the ability of Bilevel-auto to treat OSA patients whose nocturnal ventilatory disturbances are not completely corrected by CPAP. METHODS: We enrolled 66 consecutive OSA patients, not responsive to (group A) or intolerant of (group B) CPAP treatment, after a full night of manual CPAP titration in a laboratory. Full polysomnography data and daytime sleepiness score were compared for each group in the three different conditions: basal, during CPAP, and during Bilevel-auto. RESULTS: The apnea-hypopnea index decreased significantly during CPAP in both groups; however, in the group A, there was a further significant improvement during Bilevel-auto. The same trend was observed for oxygenation indices, while the distribution and the efficiency of sleep did not differ following the switch from CPAP to Bilevel-auto. CONCLUSIONS: This study confirmed the role of Bilevel-auto as an effective therapeutic alternative to CPAP in patients intolerant of this latter mode of ventilation. Moreover, extending the use of Bilevel-auto to those OSA patients not responsive to CPAP, we showed a significantly better correction of nocturnal respiratory disturbances.

The Epworth Sleepiness Scale: conventional self vs physician administration.

BACKGROUND: The Epworth Sleepiness Scale (ESS) is a simple, self-administered questionnaire that provides a measurement of the subject's level of daytime sleepiness, and is widely used for patients with obstructive sleep apnea (OSA). Some works undermined its accuracy. The aim of this study was to compare self-administered ESS scores to physician-administered scores in a sample of patients with suspicion of OSA. METHODS: Patients were randomly divided into two groups: group 1, or the self-administered group (n = 113); and group 2, or the physician-administered group (n = 112). Patients in group 1 were asked to complete the ESS in the traditional way; in group 2, the ESS was administered by a sleep-medicine physician. Subjects in both groups underwent diagnostic in-laboratory portable monitoring (PM) within 1 week's time. RESULTS: The percentage of questionnaires properly completed was significantly different between groups: 77% (87 of 113) in the group 1 vs 100% (112 of 112) in the group 2 (P = .00). Scores obtained when a physician administered the questionnaire (ESSp) were higher than those when the ESS was self administered (ESSs) (ESSp:12.09 ± 4.1 vs ESSs:10.37 ± 5.49; P = .01). The ESSp was more highly correlated with apnea-hypopnea index and oxygen desaturation index than the ESSs. CONCLUSIONS: Our results lead us to consider the physician-administered ESS to be more accurate than the traditional ESS; thus, our suggestion is to validate this new method of administration.

Reversibility of the endothelial dysfunction after CPAP therapy in OSAS patients.

BACKGROUND: The obstructive sleep apnoea syndrome (OSAS) is a common airways disease which often involves cardiovascular structures, causing vessel inflammation as well as hypoxia, induced by difficulties in the passage of air through the upper airways. Aim of our research is to evaluate the effects of Continuous Positive Airway Pressure (CPAP) on the syndrome itself and the patients cardiovascular risk profile, practically adopting Flow-Mediated Vasodilation (FMD) technique to evaluate endothelial function. METHODS AND RESULTS: We enrolled 63 patients (49 males and 14 female, mean age: 54 ± 10 years) subdivided into four groups: high cardiovascular risk factors, no CPAP therapy, CPAP therapy started less- and more than 3 months before. The patients underwent FMD of the brachial artery using a high resolution ultrasonograph connected to an image analysis system. The maximum recovery value was calculated as the ratio (maximum-baseline) of the change in diameter over the baseline value. Data obtained from this study demonstrate the significant reversibility of FMD in patients treated for more than 3 months with CPAP therapy (Group 4). CONCLUSIONS: Our study shows the importance of administering CPAP therapy for more than 3 months in patients suffering from OSAS to improve EF to a level equal to high cardiovascular risk subjects probably due to a recovery from the systemic hypoxia. Besides, our work points out the importance of FMD as a "clinical" tool able to point out any improvement or regression after therapies.

Early treatment with noninvasive positive pressure ventilation prolongs survival in Amyotrophic Lateral Sclerosis patients with nocturnal respiratory insufficiency.

BACKGROUND: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, which rapidly leads to chronic respiratory failure requiring mechanical ventilation. Currently, forced vital capacity (FVC) < 50% is considered as physiologic marker for admitting patients to Noninvasive Positive Pressure Ventilation (NPPV) intervention, although it has been recently shown the median survival of patients with baseline FVC < 75% much shorter than median survival of patients with baseline FVC > 75%, independently by any treatment. AIM: To assess the role of NPPV in improving outcome of ALS, a retrospective analysis was performed to investigate 1 year survival of ALS patients with FVC < 75% and nocturnal respiratory insufficiency, treated with NPPV, compared to a well-matched population of ALS patients, who refused or was intolerant to NPPV. METHODS: We investigated seventy-two consecutive ALS patients who underwent pulmonary function test. Forty-four presented a FVC > 75% and served as control group. Twenty-eight patients presented a FVC < 75% and showed, at polysomnography analysis, nocturnal respiratory insufficiency, requiring NPPV; sixteen were treated with NPPV, while twelve refused or were intolerant. RESULTS: Increased survival rate at 1 year in patients with FVC < 75% treated with NPPV, as compared to those who refused or could not tolerate NPPV (p = 0.02), was observed. The median rate of decline in FVC% was slower in NPPV patients than in patients who did not use NPPV (95% CI: 0.72 to 1.85; p < 0.0001). CONCLUSION: This report demonstrates that early treatment with NPPV prolongs survival and reduces decline of FVC% in ALS.