Isabelle Court-Fortune

Screening of Obstructive Sleep Apnea Syndrome by Heart Rate Variability Analysis

BACKGROUNDnEnhanced nocturnal heart rate variability (HRV) has been evoked in sleep-related breathing disorders. However, its capacity to detect obstructive sleep apnea syndrome (OSAS) has not been systematically determined. Thus, we evaluated the discriminant power of HRV parameters in a first group of patients (G1) and validated their discriminant capacity in a second group (G2).nnnMETHODS AND RESULTSnIn G1, 39 of 91 patients (42.8%) were identified as diseased by polysomnography, as were 24 of 52 patients (46%) in G2. Time-domain HRV variables (SD of NN intervals [SDNN], mean of the standard deviations of all NN intervals for all consecutive 5-minute segments of the recording [SDNN index], square root of the mean of the sum of the squares of differences between adjacent normal RR intervals [r-MSSD], and SD of the averages of NN intervals in all 5-minute segments of the recording [SDANN]) were calculated for daytime and nighttime periods, as well as the differences between daytime and nighttime values (Delta[D/N]). Correlations between HRV variables and OSAS status were analyzed in G1 by use of receiver-operating characteristic (ROC) curves and logistic regression analysis. By ROC curve analysis, 7 variables were significantly associated with OSAS. After adjustment for other variables through multiple logistic regression analysis, Delta[D/N]SDNN index and Delta[D/N] r-MSSD remained significant independent predictors of OSAS, with ORs of 8.22 (95% CI, 3.16 to 21.4) and 2.86 (95% CI, 1.21 to 6.75), respectively. The classification and regression tree methodology demonstrated a sensitivity reaching 89.7% (95% CI, 73.7 to 97.7) with Delta[D/N] SDNN index and a specificity of 98.1% (95% CI, 86.4 to 100) with Delta[D/N] SDNN using appropriate thresholds. These thresholds, applied to G2, yielded a sensitivity of 83% using Delta[D/N] SDNN index and a specificity of 96.5% using Delta[D/N] SDNN.nnnCONCLUSIONSnTime-domain HRV analysis may represent an accurate and inexpensive screening tool in clinically suspected OSAS patients and may help focus resources on those at the highest risk.

Relationship Among the Severity of Sleep Apnea Syndrome, Cardiac Arrhythmias, and Autonomic Imbalance

ROCHE, F., et al.: Relationship Among the Severity of Sleep Apnea Syndrome, Cardiac Arrhythmias, and Autonomic Imbalance. The relationship between obstructive sleep apnea syndrome (OSAS), cardiac arrhythmias, and conduction disturbances in adults remains controversial. Early studies showed a higher prevalence than more recent and designed epidemiological studies. To clarify the actual prevalence of cardiac arrhythmias and conduction disturbances in patients referred for assessment of OSAS, a prospective cohort study was conducted: 147 consecutive patients (103 men; mean age of 54.5 ± 10.7 years) underwent time‐synchronized polysomnography and ECG Holter monitoring. OSAS was diagnosed in 66 (44.9%) of them based on an apnea hypopnea index (AHI) ≥10. Prevalence of heart failure, of prior myocardial infarction, of hypertension, and of ventricular arrhythmias were similar in patients with or without OSAS. Nocturnal paroxysmal asystole was significantly more prevalent in OSAS patients (10.6 vs 1.2%; P < 0.02) and the number of episodes of bradycardia and pauses increased with the severity of the syndrome. Almost all bradycardic events occurred in patients with severe OSAS (AHI > 30), prolonged periods of arterial oxyhemoglobin desaturation, and low diurnal awake PaO2. Moreover, using heart rate variability analysis, nocturnal sinusal dysfunction contrasted with a blunted diurnal parasympathetic modulation of the sinus node. Frequent nocturnal nonsustained supraventricular tachycardias were predominantly found in patients with severe sleep related breathing disorders; however, an increased risk of ventricular arrhythmias was not found. Under continuous positive airway pressure treatment, the 1‐year follow‐up of OSAS patients with nocturnal pauses did not reveal any arrhythmic event justifying a specific intervention. (PACE 2003; 26:669–677)

Multimodal nutritional rehabilitation improves clinical outcomes of malnourished patients with chronic respiratory failure: a randomised controlled trial

Background In chronic respiratory failure (CRF), body composition strongly predicts survival. Methods A prospective randomised controlled trial was undertaken in malnourished patients with CRF to evaluate the effects of 3u2005months of home rehabilitation on body functioning and composition. 122 patients with CRF on long-term oxygen therapy and/or non-invasive ventilation (mean (SD) age 66 (10)u2005years, 91 men) were included from eight respiratory units; 62 were assigned to home health education (controls) and 60 to multimodal nutritional rehabilitation combining health education, oral nutritional supplements, exercise and oral testosterone for 90u2005days. The primary endpoint was exercise tolerance assessed by the 6-min walking test (6MWT). Secondary endpoints were body composition, quality of life after 3u2005months and 15-month survival. Results Mean (SD) baseline arterial oxygen tension was 7.7 (1.2)u2005kPa, forced expiratory volume in 1u2005s 31 (13)% predicted, body mass index (BMI) 21.5 (3.9)u2005kg/m2 and fat-free mass index (FFMI) 15.5 (2.4)u2005kg/m2. The intervention had no significant effect on 6MWT. Improvements (treatment effect) were seen in BMI (+0.56u2005kg/m2, 95% CI 0.18 to 0.95, p=0.004), FFMI (+0.60u2005kg/m2, 95% CI 0.15 to 1.05, p=0.01), haemoglobin (+9.1u2005g/l, 95% CI 2.5 to 15.7, p=0.008), peak workload (+7.2u2005W, 95% CI 3.7 to 10.6, p<0.001), quadriceps isometric force (+28.3u2005N, 95% CI 7.2 to 49.3, p=0.009), endurance time (+5.9u2005min, 95% CI 3.1 to 8.8, p<0.001) and, in women, Chronic Respiratory Questionnaire (+16.5 units, 95% CI 5.3 to 27.7, p=0.006). In a multivariate Cox analysis, only rehabilitation in a per-protocol analysis predicted survival (HR 0.27, 95% CI 0.07 to 0.95, p=0.042). Conclusions Multimodal nutritional rehabilitation aimed at improving body composition increased exercise tolerance, quality of life in women and survival in compliant patients, supporting its incorporation in the treatment of malnourished patients with CRF. Clinical Trial number NCT00230984.

Noninvasive ventilation during exercise training improves exercise tolerance in patients with chronic obstructive pulmonary disease.

PURPOSEnIn patients with chronic obstructive pulmonary disease, pulmonary rehabilitation has been demonstrated to increase exercise capacity and reduce dyspnea. In the most disabled patients, the intensity of exercise during the training sessions is limited by ventilatory pump capacity. This study therefore evaluated the beneficial effect of noninvasive ventilation (NIV) support during the rehabilitation sessions on exercise tolerance.nnnMETHODSnThis study included 14 patients with stabilized chronic obstructive pulmonary disease, ages 63 +/- 7 years, with a forced expiratory volume in 1 second (FEV(1)) 31.5% +/- 9.2% of predicted value. All 14 patients participated in an outpatient pulmonary rehabilitation program. Seven of the patients trained with NIV during the exercise sessions (NIV group), whereas the remaining seven patients breathed spontaneously (control group). Exercise tolerance was evaluated during an incremental exercise test and during constant work rate exercise at 75% of peak oxygen consumption (VO(2)) before and after the training program.nnnRESULTSnThe application of noninvasive ventilation increased exercise tolerance, reduced dyspnea, and prevented exercise-induced oxygen desaturation both before and after training. The pressure support was well tolerated by all the patients during the course of the training program. In the NIV group, training induced a greater improvement in peak VO(2) (18% vs 2%; P <.05) and a reduced ventilatory requirement for maximal exercise, as compared with the control group. The constant work rate exercise duration increased similarly in both groups (116% vs 81%, nonsignificant difference), and posttraining blood lactate was decreased at isotime (P <.05 in both groups), but not at the end of the exercise.nnnCONCLUSIONnIn this pilot study, exercise training with noninvasive ventilation support was well tolerated and yielded further improvement in the increased exercise tolerance brought about by pulmonary rehabilitation in patients with chronic obstructive pulmonary disease. This improved exercise tolerance is partly explained by a better ventilatory adaptation during exercise.

Cardiac Interbeat Interval Increment for the Identification of Obstructive Sleep Apnea

ROCHE, F., et al.: Cardiac Interbeat Interval Increment for the Identification of Obstructive Sleep Apnea. The prevalence of obstructive sleep apnea syndrome (OSAS) is high in developed countries but its diagnosis is costly. Based on physiological evidence, the frequency component of heart rate variability (HRV) was evaluated as a simple and inexpensive diagnostic tool in OSAS. The predictive accuracy of frequency‐domain HRV variables obtained from 24‐hour ECG Holter monitoring (the power spectral density of the interbeat interval increment of very low frequencies, “VLFIpsd,” and its percentage over the total power spectral density, “%VLFI”), and of established time‐domain HRV variables were analyzed by comparison with respiratory disturbances indexes assessed by complete polysomnography in 124 consecutive patients (98 men aged 53.8 ± 11.2 years) with clinically suspected OSAS. OSAS was present in 54 (43.5%) patients according to standard criteria. Using receiver operating characteristic curve analysis, two of the three most powerful predictors were frequency‐domain variables: %VLFI (W = 0.80, P < 0.0001), and VLFIpsd (W = 0.79, P < 0.0001). Using a multiple logistic regression analysis, %VLFI was the most strongly associated with diseased status (adjusted OR: 8.4; 95% CI: 3.4–19.5). Using an appropriate threshold, %VLFI demonstrated a diagnostic sensitivity of 87%. A 3‐month continuous positive airway pressure treatment significantly improved the same parameter. Frequency‐domain analysis of the interbeat interval increment appears as a powerful tool for OSAS diagnosis and follow‐up. The simplicity of its analysis and of its use makes of it a well‐suited variable for mass screening of OSAS patients.

Alteration of QT Rate Dependence Reflects Cardiac Autonomic Imbalance in Patients with Obstructive Sleep Apnea Syndrome

QT rate dependence is one of the major properties of ventricular repolarization with its circadian and autonomic modulations. The authors postulated that dynamic alterations in QT interval adaptation could help characterize patients with cardiac autonomic alterations, like those with obstructive sleep apnea syndrome (OSAS). To assess ventricular repolarization features in patients with OSAS, QT parameters and their dynamicity along RR intervals were compared from 24‐hour ECG data of patients with and without this syndrome, assessing cardiac autonomic nervous system equilibrium by means of time‐domain and frequency‐domain analyses of heart rate variability (HRV). The study group consisted of 74 consecutive patients referred to the Sleep Laboratory for clinically suspected OSAS. The syndrome was confirmed in 30 (40.5%) patients according to standard polysomnographic criteria. QT length related to heart rate (HR) was found significantly shorter for HR < 70 beats/min in patients with OSAS (−1.32 ± 0.35) compared with patients without OSAS (−1.99 ± 0.40; P < 0.01) . This flattened relationship was correlated with the severity of the sleep related disorder. Using multiple linear regression analysis, the apnea/hypopnea index and nocturnal normalized high frequencies (HFnu) were the most significant predictors of the QT/RR slope (R = 0.61; P < 0.0001) . OSAS is significantly associated with a flattened relationship between QT duration and RR interval at low HRs. The alteration of cardiac parasympathetic tone occuring in severe OSAS patients may explain this altered rate dependent adaptation of myocardial repolarization. (PACE 2003; 26[Pt. I]:1446–1453)

Survival of patients with chronic respiratory failure on long-term oxygen therapy and or non-invasive ventilation at home.

BACKGROUND & AIMSnChronic respiratory failure (CRF) is the common fate of respiratory diseases where systemic effects contribute to outcomes. In a prospective cohort of home-treated patients with CRF, we looked for predictors of long-term survival including respiratory, nutritional and inflammatory dimensions.nnnMETHODSn637 stable outpatients with CRF, 397 men, 68 ± 11 years, on long-term oxygen therapy and/or non-invasive ventilation from 21 chest clinics were enrolled and followed over 53 ± 31 months. CRF resulted from Chronic Obstructive Pulmonary Disease (COPD) in 48.5%, restrictive disorders 32%, mixed (obstructive and restrictive patterns) respiratory failure 13.5%, bronchiectasis 6%. Demographic characteristics, smoking habits, underlying respiratory diseases, forced expiratory volume in one second (FEV1), forced vital capacity (FVC), arterial blood gases, 6-min walking distance (6MWD), hemoglobin, body mass index (BMI), serum albumin, transthyretin, C-reactive protein (CRP), history of respiratory assistance, antibiotic and oral corticosteroid use during the previous year were recorded.nnnRESULTSn322 deaths occurred during the follow-up. One-, five- and 8-year actuarial survival was 89%, 56% and 47%. By Cox univariate analysis, age, respiratory disease, PaO2, PaCO2, FEV1/FVC, BMI, 6MWD, activity score, type and length of home respiratory assistance, smoking habits, oral corticosteroid and antibiotic uses, albumin, transthyretin, hemoglobin and CRP levels were associated with survival. Multivariate analysis identified eight independent markers of survival: age, FEV1/FVC, PaO2, PaCO2, 6MWD, BMI, serum transthyretin, CRP ≥ 5 mg/l.nnnCONCLUSIONSnIn CRF, whatever the underlying diseases, besides the levels of obstructive ventilatory defect and gas exchange failure, 6MWD, BMI, serum transthyretin and CRP ≥ 5 mg/l predicted long-term survival identifying potential targets for nutritional rehabilitation.

ECG-derived respiration: A promising tool for sleep-disordered breathing diagnosis in chronic heart failure patients☆

Theprevalenceofsleep-disorderedbreathing(SDB)inchronicheartfailure (CHF) patients exceeds 60%, including both central sleep apnea(CSA)andobstructivesleepapnea(OSA)[1].Asobservedinthegeneralpopulation, SDB in CHF patients is associated with a poor prognosis [2]and a higher risk of nocturnal arrhythmia [3]. Continuous positiveairway pressure or adaptive servo-ventilation treatments might im-provebothLVEFandmortalityandreducetheriskofarrhythmicevents,but this remains debatable [4]. Nevertheless, at least 75% of severe SDBcasesremainundiagnosedanduntreatedduetotheabsenceofdaytimesymptoms, waiting lists in sleep laboratories, and diagnostic costs. Thehigh SDB prevalence in patients referred for cardiologic assessmentcalls for the development of automated screening tools based on ECG-derived parameters for use by cardiologists in routine practice.MethodsbasedonheartratevariabilityanalysisallowdetectingSDBpatients whopresentsinusal rhythm[5] butare not suitable for cardiacfailureordysautonomicpopulations,whofrequentlyexhibitprematureatrial or ventricular beat, are frequently implanted with permanentpacemakers, or present recurrent atrial fibrillation, bundle branchblocks, or flat heart rate variability [6]. ECG-derived respiration (EDR),a method based on the reconstruction of thoracic signals by analysingchangesinECGmorphologythatareinducedbyrespiratorymovements[7], is a promisingalternative,but has not yet been evaluatedincardiacpopulations [8].Werecruited105patientswithLVEFb45%andNYHAclass≥2fromroutine medical follow-ups of stable CHF patients (Saint-Etienne andGrenoble University Hospitals) to test an automated EDR method withreference to visually scored nocturnal in-home ventilatory polygraphy.This study (clinical trial NCT02116686) complies with the DeclarationofHelsinkiandwasapprovedbythelocalethicscommittee.Allpatientsgave their written informed consent to participate.Standard nocturnal in-home ventilatory polygraphy was performedusinganEmbladevice(Embla®,Broomfield,USA)andscoredaccordingto AASM recommendations using RemLogic® software. Based onpreviously published methods [7,9,10] and developed with Matlab®(Mathworks,Natick,USA),anEDRmethodwasusedasfollows:thoracicmovements derived from ECG signals were analysed in order toreconstruct respiratory movements. The two mechanisms involved,changesintheelectricalheartaxisandchangesintransthoracicimped-ance,areeasilyobservedintheQRSheightorarea,allowingreconstruc-tion of the thoracic signal, which is then used to score apnea andhypopnea events [7]. Analyses were performed on the portion of thepolygraphic ECG signal recorded when the light was turned off. TheECG baseline was removed, each R-peak was detected, and R-peakoutliers were excluded. The EDR signal was then calculated as thesuccessive surfaces of each QRS complex under the R-peak. An SDBevent was then scored when the algorithm detected either a 50%decrease in thepeak-to-peak EDR amplitudefor 10 s [9] or an invertedU-shape of the EDR trace corresponding to a baseline drift due torespiratory effort during obstruction [10].ECG results were subjected to automated analysis only, and poly-graph recordings were scored manually and blinded to EDR results. Uni-variate regression analysis for continuous variables and Bland–Altmanplot were used to assess the relationship between the polygraphicapnea/hypopnea index (AHI

Influence des facteurs sociogéographiques et des pratiques médicales sur la survie des patients suivis dans un centre SLA. Étude rétrospective de 203 patients

Introduction La prise en charge de la sclerose laterale amyotrophique (SLA) repose essentiellement sur la compensation du handicap moteur, de la denutrition et de l’insuffisance respiratoire. Objectifs Depuis 2003, elle est coordonnee par des centres specialises suivant les recommandations internationales et implique de nombreux acteurs. Tous ces acteurs contribuent a la survie. Leur poids respectif n’a ete que peu etudie. Methodes A partir du registre du centre SLA de Saint-Etienne, nous avons analyse ces facteurs (acteurs de proximite medicaux, paramedicaux, sociaux ainsi que l’entourage familial du patient) et nos pratiques, chez 203xa0patients, suivis en equipe pluridisciplinaire sur la periode 2003–2011xa0et pour lesquels nous disposions de donnees completes. La survie a ete etudiee par methode de Kaplan-Meyer et modele de Cox et les pratiques par regression logistique. Resultats La mediane de survie etait de 28,9xa0mois. Elle etait influencee par des facteurs propres a la maladie (âge, siege de l’atteinte initiale, capacite vitale forcee initiale et evolutivite). La taille de la commune et le departement de residence n’influencaient pas la survie contrairement au lieu de residence (domicile-institution), l’entourage familial et l’organisation des soins a domicile. Concernant les pratiques de soin, la gastrostomie n’ameliorait pas la survie contrairement a la ventilation non invasive (VNI). Discussion Parmi les patients relevant, selon les recommandations, d’une gastrostomie ou d’une VNI, la realisation de l’intervention therapeutique a ete influencee par l’evolutivite de la maladie, un suivi prolonge du patient et des facteurs lies au cadre de vie. L’organisation en reseau des soins jouent positivement sur la survie. Cette etude montre une homogeneite territoriale de la prise en charge des patients dans le bassin d’attraction du centre SLA. Conclusion L’etude souligne le role des facteurs de proximite entourant le patient, tant dans la survie, que dans les decisions therapeutiques prises par le centre SLA.