Effects of Obstructive Sleep Apnea on Hemodynamic Parameters in Patients Entering Cardiac Rehabilitation

Non-Invasive Assessment of Cardiodynamics by Impedance Cardiography during the Six-Minute Walk Test in Patients with Heart Failure

BACKGROUND

Central Illustration: Non-Invasive Assessment of Cardiodynamics by Impedance Cardiography during the Six-Minute Walk Test in Patients with Heart Failure. The six-minute walk test (6MWT) is commonly used to evaluate heart failure (HF) patients. However, several clinical factors can influence the distance walked in the test. Signal-morphology impedance cardiography (SM-ICG) is a useful tool to noninvasively assess hemodynamics.

OBJECTIVE

This study aimed to compare cardiac output (CO), heart rate (HR), and stroke volume (SV) acceleration and deceleration responses to 6MWT in individuals with HF and reduced ejection fraction (HFrEF) and healthy controls.

METHODS

This is a cross-sectional observational study. CO, HR, SV and cardiac index (CI) were evaluated before, during, and after the 6MWT assessed by SM-ICG. The level of significance adopted in the statistical analysis was 5%.

RESULTS

Twenty-seven participants were included (13 HFrEF and 14 healthy controls). CO and HR acceleration significantly differed between groups (p<0.01; p=0.039, respectively). We found significant differences in SV, CO and CI between groups (p<0.01). Linear regression showed an impaired SV contribution to CO change in HFrEF group (22.9% versus 57.4%).

CONCLUSION

The main finding of the study was that individuals with HFrEF showed lower CO and HR acceleration values during the submaximal exercise test compared to healthy controls. This may indicate an imbalance in the autonomic response to exercise in this condition.

Decreased cardiac output: an integrative review

OBJECTIVE

to identify, in the scientific literature, the defining characteristics and contributing factors (related factors, associated conditions and populations at risk) for nursing diagnosis decreased cardiac output.

METHOD

an integrative literature review, conducted between September and October 2020, with an update in March 2022, in the MEDLINE via PubMed, LILACS, SciELO, CINAHL and EMBASE databases. Using acronym PEO, studies published in the last 10 years in Portuguese, English and Spanish were included. A descriptive analysis was carried out to present the elements mapped in the literature.

RESULTS

analysis of 31 articles identified different elements, highlighting 4 new related factors: hyperglycemic stress, prone position, left lateral position, sleep deprivation. Individuals with a history of cardiovascular disease and males were identified as possible populations at risk.

FINAL CONSIDERATIONS

the elements for decreased cardiac output, identified in the literature, add evidence that justifies the permanence of this diagnosis in the NANDA-I classification.

Débito cardíaco diminuído: revisão integrativa

RESUMO Objetivo: identificar, na literatura científica, as características definidoras e fatores contribuintes (fatores relacionados, condições associadas e populações em risco) para o diagnóstico de enfermagem débito cardíaco diminuído. Método: revisão integrativa da literatura, conduzida entre setembro e outubro de 2020, com atualização em março de 2022, nas bases de dados MEDLINE via PubMed, LILACS, SciELO, CINAHL e EMBASE. Com uso do acrônimo PEO, foram incluídos estudos publicados nos últimos 10 anos em português, inglês e espanhol. Realizouse análise descritiva para apresentar os elementos mapeados na literatura. Resultados: análise de 31 artigos identificou diferentes elementos, com destaque para 4 novos fatores relacionados: estresse hiperglicêmico, posição prona, posição lateral esquerda, privação do sono. Indivíduos com história de doença cardiovascular e do sexo masculino foram apontados como possíveis populações em risco. Considerações finais: os elementos para débito cardíaco diminuído, identificados na literatura, agregam evidências que justificam a permanência desse diagnóstico na classificação da NANDA-I.

Prevalence, Impact, and Trajectories of Sleep Disturbance in Cardiac Rehabilitation: A NARRATIVE REVIEW AND SUGGESTIONS FOR EVALUATION AND TREATMENT

OBJECTIVE

The aim of this review was to summarize literature examining the prevalence, impact, and trajectories of sleep disturbance in cardiac rehabilitation (CR) patients and discuss how CR programs may incorporate targeted evaluation and interventions to promote sleep health.

REVIEW METHODS

A narrative review of literature allowed for an examination of the prevalence of sleep disturbance in CR patients, the effects of sleep disturbance on CR outcomes, and trajectories of sleep disturbance in CR.

SUMMARY

Sleep disturbance is prevalent in CR patient populations and is related to clinical and functional outcomes. Sleep may be an important biobehavioral process to target in CR to improve important patient outcomes and achieve secondary prevention goals.

OSA and cardiorespiratory fitness: a review

The effects of untreated obstructive sleep apnea (OSA) on cardiopulmonary function remain unclear. Cardiorespiratory fitness (CRF), commonly reflected by VO₂ max measured during cardiopulmonary exercise testing, has gained popularity in evaluating numerous cardiopulmonary conditions and may provide a novel means of identifying OSA patients with the most clinically significant disease. This emerging testing modality provides simultaneous assessment of respiratory and cardiovascular function with results helping uncover evidence of evolving pathology in either organ system. In this review, we highlight the current state of the literature in regard to OSA and CRF with a specific focus on changes in cardiovascular function that have been previously noted. While OSA does not appear to limit respiratory function during exercise, studies seem to suggest an abnormal cardiovascular exercise response in this population including decreased cardiac output, a blunted heart rate response (ie, chronotropic incompetence), and exaggerated blood pressure response. Surprisingly, despite these observed changes in the cardiovascular response to exercise, results involving VO₂ max in OSA remain inconclusive. This is reflected by VO₂ max studies involving middle-aged OSA patients showing both normal and reduced CRF. As prior studies have not extensively characterized oxygen desaturation burden, we propose that reductions in VO₂ max may exist in OSA patients with only the most significant disease (as reflected by nocturnal hypoxia). Further characterizing this relationship remains important as some research suggests that positive airway pressure therapy or aerobic exercise may improve CRF in patients with OSA. In conclusion, while it likely that severe OSA, via an abnormal cardiovascular response to exercise, is associated with decreased CRF, further study is clearly warranted to include determining if OSA with decreased CRF is associated with increased morbidity or mortality.

CITATION

Powell TA, Mysliwiec V, Brock MS, Morris MJ. OSA and cardiorespiratory fitness: a review. J Clin Sleep Med. 2022;18(1):279-288.

Does an undetected obstructive sleep apnea influence the natural course and success of cardiac rehabilitation after cardiac surgery?

BACKGROUND

Obstructive Sleep Apnea (OSA) is common in patients with cardiovascular diseases (CVD) and can negatively impact the course of CVD. However, scarce data are available for patients before or after cardiac surgery (CS) in the context of OSA.

AIM

This study investigated the impact of an undetected OSA on the results of cardiac rehabilitation (CR) in patients after CS.

DESIGN

Observational study over a period of 3 months following CS.

SETTING

The setting of this study was inpatient CR after CS or cardiac interventions.

POPULATION

CS cohort referred to a CR program to an inpatient rehabilitation clinic in Switzerland.

METHODS

In this prospective observational study 256 patients were screened for OSA at the entry of CR via a level III screening device (ApneaLink Air^TM, Resmed, San Diego, CA, USA). They were stratified into two groups: apnea hypopnea index (AHI) >15 or <15/h. A comprehensive assessment was performed at entry and end of CR including six-minute walk test (6-MWT), Functional Independence Measure (FIM), Hospital Anxiety and Depression Scale, MacNewHeart (MNH), STOP-Bang Questionnaire (SBQ) and Epworth Sleepiness Scale (ESS).All patients participated in a comprehensive CR program with a mean duration of approximately 3 weeks. Another OSA screening was performed at the end of the PR program and after 3 months in order to observe the clinical course of OSA.

RESULTS

An AHI>15/h was found in 133 patients (59%) at baseline, 54% after 3 weeks and 43% after 3 months. The AHI>15/h-group was older, had a higher BMI, more frequent hypertension and coronary artery disease, and higher ESS and SBQ scores compared to the AHI<15/h-group. The results of the STOP-Bang and ESS questionnaires showed a statistically significant but weak positive correlation with AHI. However, in both groups ESS did not improve from baseline to the end of CR. A multivariable logistic regression model confirmed age and ESS as independent positive predictors of OSA. No differences were found between both groups according to the results of the 6-MWT, HADS and MNH.

CONCLUSIONS

OSA had a high prevalence in a large CS cohort referred to CR. However, moderate-severe OSA, though symptomatic, had no significant influence on the outcome during CR and on the parameters representing success.

CLINICAL REHABILITATION IMPACT

In our study the improvements during CR after CS were not influenced by the presence of significant OSA which is remarkable since the presence of OSA is thought to be associated with increased rates of cardiovascular adverse events after cardiovascular intervention or CS. This is true at least for the success of CR after CS. The long-term consequences of untreated OSA in CVD remain unclear and are still the subject of current research.

Prevalence of obstructive sleep apnoea in acute coronary syndrome patients: systematic review and meta-analysis

Background

Obstructive Sleep Apnoea (OSA) has been recognised as a risk factor for cardiovascular diseases such as hypertension and cardiovascular events such as acute coronary syndrome (ACS). Since it is also known to reduce exercise tolerance, it is important to establish the prevalence of OSA in ACS patients, particularly in those who are commencing cardiac rehabilitation (CR) programs.

Methods

Using PRISMA guidelines a systematic search was conducted in order to identify studies that objectively measured (using polysomnography or portable monitoring) the prevalence of OSA in ACS patients following hospital admission. A data extraction table was used to summarise study characteristics and the quality of studies were independently assessed using the Joanna Briggs Institute Prevalence Critical Appraisal Tool. Meta-analysis of the selected studies was conducted in order to estimate OSA prevalence as a function of the two main methods of measurement, the severity of OSA, and timing of the OSA assessment following ACS hospital admission.

Results

Pooled prevalence estimates of OSA using the “gold standard” polysomnography ranged from 22% for severe OSA to 70% for mild OSA, at any time after hospital admission. Similar prevalence estimates were obtained using portable monitoring, but interpretation of these results are limited by the significant heterogeneity observed among these studies.

Conclusions

Prevalence of OSA following ACS is high and likely to be problematic upon patient entry into CR programs. Routine screening for OSA upon program entry may be necessary to optimise effectiveness of CR for these patients.

Prevalence of Sleep-Disordered Breathing and Patient Characteristics in a Coronary Artery Disease Cohort Undergoing Cardiovascular Rehabilitation

PURPOSE

Coronary artery disease (CAD) is a leading cause of death and identification of risk factors for CAD is crucial. One such potential risk factor is sleep-disordered breathing (SDB). This prospective cohort study investigated the prevalence of SDB and determined risk factors for the presence of SDB in a large CAD cohort undergoing cardiac rehabilitation.

METHODS

A total of 1425 patients with confirmed CAD starting rehabilitation were screened for SDB using cardiorespiratory polygraphy (n = 921) or polygraphy plus pulse oximetry (n = 484).

RESULTS

A total of 1408 patients were included; 69.5% were male, 78% had acute coronary syndrome, and 22% had stable CAD. The prevalence of SDB (apnea-hypopnea index [AHI] ≥5/h) was 83%. Moderate to severe SDB (AHI ≥15/h) was present in 53%. Up to 70% of coronary artery bypass graft (CABG) recipients had an AHI ≥15/h versus 33% of those who had not undergone CABG. SDB severity did not vary significantly in patients with stable CAD or on the basis of left ventricular ejection fraction. SDB was more severe and the frequency of oxygen desaturation was higher in men than in women. Multivariate logistic regression identified age, sex, body mass index, and CABG as independent risk factors for severe SDB.

CONCLUSION

SDB is a highly prevalent comorbidity in patients with CAD, particularly those who have undergone CABG. These results strengthen existing associations and emphasize the importance of diagnosing and monitoring SDB in patients with CAD entering a cardiac rehabilitation program. Early diagnosis and intervention has the potential to have a beneficial effect on CAD prognosis.

Rehabilitation of Cardiovascular Disorders and Sleep Apnea

Obstructive sleep apnea (OSA) is present in more than 50% of patients referred to cardiac rehabilitation units. However, it has been under-recognized in patients after stroke and heart failure. Those with concurrent OSA have a worse clinical course. Early treatment of coexisting OSA with continuous positive airway pressure (CPAP) results in improved rehabilitation outcomes and quality of life. Possible mechanisms by which CPAP may improve recovery include decreased blood pressure fluctuations associated with apneas, and improved left ventricular function, cerebral blood flow, and oxygenation. Early screening and treatment of OSA should be integral components of patients entering cardiac rehabilitation units.