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Atrial remodeling in obstructive sleep apnea: implications for atrial fibrillation.

BACKGROUND There is a known association between obstructive sleep apnea (OSA) and atrial fibrillation (AF); however, how OSA affects the atrial myocardium is not well described. OBJECTIVE To determine whether patients with OSA have an abnormal atrial substrate. METHODS Forty patients undergoing ablation of paroxysmal AF and in sinus rhythm (20 with OSA [apnea-hypopnea index ≥ 15] and 20 reference patients with no OSA [apnea-hypopnea index < 15] by polysomnography) were studied. Multipolar catheters were positioned at the lateral right atrium (RA), coronary sinus, crista terminalis, and RA septum to determine the effective refractory period at 5 sites, conduction time along linear catheters at the RA and the coronary sinus, conduction at the crista terminalis, and sinus node function (corrected sinus node recovery time). Biatrial electroanatomic maps were created to determine the voltage, conduction, and distribution of complex electrograms (duration ≥ 50 ms). RESULTS The groups had no differences in the prevalence of established risk factors for AF. Patients with OSA had the following compared with those without OSA: no difference in effective refractory period (P = .9), prolonged conduction times along the coronary sinus and RA (P = .02), greater number (P = .003) and duration (P = .03) of complex electrograms along the crista terminalis, longer P-wave duration (P = .01), longer corrected sinus node recovery time (P = .02), lower atrial voltage (RA, P <.001; left atrium, P <.001), slower atrial conduction velocity (RA, P = .001; left atrium, P = .02), and more widespread complex electrograms in both atria (RA, P = .02; left atrium, P = .01). CONCLUSION OSA is associated with significant atrial remodeling characterized by atrial enlargement, reduction in voltage, site-specific and widespread conduction abnormalities, and longer sinus node recovery. These features may in part explain the association between OSA and AF.

Early investigation and treatment of obstructive sleep apnoea after acute stroke

Obstructive sleep apnoea (OSA) is an independent risk factor for hypertension, which is a major cause of stroke. The prevalence and associations of OSA in a cohort of stroke patients were studied. The safety and tolerability of early treatment with nasal continuous airways pressure (nCPAP) was also assessed. Consecutive subjects admitted with acute stroke were assessed clinically, radiologically and with scales assessing prior OSA risk, dysphagia and disability. Sleep studies were performed within the first few days of admission using a portable diagnostic system. Twenty-nine of 55 (53%) subjects had evidence of OSA, using an apnoea-hypopnoea index (AHI) of 10 or greater. The AHI was significantly associated with an index of prior OSA symptoms, but not with history of hypertension, degree of dysphagia, or type and severity of stroke. Use of a portable diagnostic system for detecting OSA in the acute stroke setting was well tolerated. OSA is common after acute stroke and exceeds rates seen in control populations of similar age (53% vs. 11%). Early treatment with nCPAP was effective and well tolerated.

Disordered respiration as a levodopa‐induced dyskinesia in Parkinson's disease

Symptomatic respiratory disturbance as a consequence of levodopa (L‐dopa) therapy for Parkinsons disease (PD) has been described only rarely and may be underrecognized in clinical practice. We report on two patients with PD in whom the introduction or augmentation of L‐dopa therapy was associated with the development of irregular and rapid breathing. Analysis of breathing patterns before and after L‐dopa demonstrated a striking change in respiratory rate after administration of L‐dopa, with the emergence of irregular tachypnea alternating with brief periods of apnea, in a pattern consistent with a central origin. In both cases, the temporal relationship of the respiratory disturbance to the administration of L‐dopa suggested a peak‐dose drug effect. Previous reports of L‐dopa–induced respiratory dyskinesia are reviewed, and the potential mechanisms whereby L‐dopa might influence the central control of respiration to produce irregular breathing patterns are discussed.

Barriers to, and facilitators for, referral to pulmonary rehabilitation in COPD patients from the perspective of Australian general practitioners: a qualitative study

Background: Pulmonary rehabilitation (PR) is recommended in the management of people with chronic obstructive pulmonary disease (COPD), but referral to this service is low. Aims: To identify barriers to, and facilitators for, referral to PR programmes from the perspective of Australian general practitioners. Methods: Semi-structured interviews were conducted with general practitioners involved in the care of people with COPD. Interview questions were informed by a validated behavioural framework and asked about participants’ experience of referring people with COPD for PR, and barriers to, or facilitators of, this behaviour. Interviews were audiotaped, transcribed verbatim, and analysed using content analysis. Results: Twelve general practitioners participated in this study, 10 of whom had never referred a patient to a PR programme. Four major categories relating to barriers to referral were identified: low knowledge of PR for COPD; low knowledge of how to refer; actual or anticipated access difficulties for patients; and questioning the need to do more to promote exercise behaviour change. Awareness of benefit was the only current facilitator. Three major categories of potential facilitators were identified: making PR part of standard COPD care through financial incentive; improving information flow with regard to referrals and services; and informing patients and public. Conclusions: Significant barriers to referral exist, but opportunities to change the organisation of practice and information management were identified. Behaviour change strategies which directly target these barriers and incorporate facilitators should make up the key components of interventions to improve referral to PR by general practitioners who care for people with COPD.

Why are some evidence-based care recommendations in chronic obstructive pulmonary disease better implemented than others? Perspectives of medical practitioners.

Background Clinical guidelines for management of patients with chronic obstructive pulmonary disease (COPD) include recommendations based on high levels of evidence, but gaps exist in their implementation. The aim of this study was to examine the perspectives of medical practitioners regarding implementation of six high-evidence recommendations for the management of people with COPD. Methods Semi-structured interviews were conducted with medical practitioners involved with care of COPD patients in hospital and general practice. Interviews sought medical practitioners’ experience regarding implementation of smoking cessation, influenza vaccination, pulmonary rehabilitation, guideline-based medications, long-term oxygen therapy for hypoxemia and plan and advice for future exacerbations. Interviews were audiotaped, transcribed verbatim and analyzed using content analysis. Results Nine hospital-based medical practitioners and seven general practitioners participated. Four major categories were identified which impacted on implementation of the target recommendations in the care of patients with COPD: (1) role clarity of the medical practitioner; (2) persuasive communication with the patient; (3) complexity of behavioral change required; (4) awareness and support available at multiple levels. For some recommendations, strength in all four categories provided significant enablers supporting implementation. However, with regard to pulmonary rehabilitation and plans and advice for future exacerbations, all identified categories that presented barriers to implementation. Conclusion This study of medical practitioner perspectives has indicated areas where significant barriers to the implementation of key evidence-based recommendations in COPD management persist. Developing strategies to target the identified categories provides an opportunity to achieve greater implementation of those high-evidence recommendations in the care of people with COPD.

Cardiorespiratory Phase-Coupling Is Reduced in Patients with Obstructive Sleep Apnea

Cardiac and respiratory rhythms reveal transient phases of phase-locking which were proposed to be an important aspect of cardiorespiratory interaction. The aim of this study was to quantify cardio-respiratory phase-locking in obstructive sleep apnea (OSA). We investigated overnight polysomnography data of 248 subjects with suspected OSA. Cardiorespiratory phase-coupling was computed from the R-R intervals of body surface ECG and respiratory rate, calculated from abdominal and thoracic sensors, using Hilbert transform. A significant reduction in phase-coupling was observed in patients with severe OSA compared to patients with no or mild OSA. Cardiorespiratory phase-coupling was also associated with sleep stages and was significantly reduced during rapid-eye-movement (REM) sleep compared to slow-wave (SW) sleep. There was, however, no effect of age and BMI on phase coupling. Our study suggests that the assessment of cardiorespiratory phase coupling may be used as an ECG based screening tool for determining the severity of OSA.

The Australian National Asthma Campaign: effects of public education activities based on mass media.

INTRODUCTION The National Asthma Campaign (NAC) was formed in 1990 as a coalition of the key professional organizations concerned with asthma and its management in Australia. It has conducted multifaceted educational activities targeting health care professionals, people with asthma, and the general public. Between November 1991 and March 1993, an educational mass media campaign was developed to inform people about new approaches to preventive asthma therapy and how people with symptoms of asthma should talk to their doctor or pharmacist about new management and monitoring strategies. Evaluation was based on McGuires communication/persuasion model for assessing the impact of mass media campaigns. METHODS Four serial cross-sectional population surveys of persons over the age of 18 years were conducted in four major Australian cities using structured telephone interviews. Information was sought on asthma campaign awareness and knowledge or use of appropriate asthma management practices. RESULTS There was an increasing trend in awareness of asthma messages in the media and of appropriate message recall across the two-year period. Knowledge about the need to use preventive therapy for asthma improved significantly. Among those with asthma there was a significant upward trend in the proportion who discussed asthma with their doctor or pharmacist and who used peak flow meters and written asthma management plans. CONCLUSIONS The net impact of the NAC and other activities has been an increase in awareness about asthma in Australia. These campaigns relied on the relatively nonselective medium of television to raise awareness and to start to change attitudes to asthma. The challenge is to build on these trends to further reduce morbidity and mortality due to asthma.

PERCUTANEOUS ASPIRATION BIOPSY OF DISCRETE LUNG LESIONS

Using a fine bore needle and image‐amplification fluoroscopic guidance, percutaneous aspiration biopsies were performed on 59 patients with discrete lung lesions. Diagnostic accuracy of malignancy was 80%; correlation in tumor typing when compared with histologic diagnoses made from autopsy or operative material was good. Two methods of cytologic preparation, by direct smear and Nuclepore filter, were compared with histologic sections of the aspirate, the most reliable preparation being the smear made directly from fresh aspirate. It is concluded that the percutaneous aspiration biopsy is a reliable additional method of diagnosing lung cancer, that it can be successfully employed for lesions out of reach of the bronchoscope, including those in the upper lobes, and that it has particular application in tumors which are inoperable, whether due to the stage of malignancy, the poor general condition of the patient, or the presence of metastases.

Which chronic obstructive pulmonary disease care recommendations have low implementation and why? A pilot study

BackgroundClinical care components for people with COPD are recommended in guidelines if high-level evidence exists. However, there are gaps in their implementation, and factors which act as barriers or facilitators to their uptake are not well described. The aim of this pilot study was to explore implementation of key high-evidence COPD guideline recommendations in patients admitted to hospital with a disease exacerbation, to inform the development of a larger observational study.MethodsThis study recruited consecutive COPD patients admitted to a tertiary hospital. Patient demographic, disease and admission characteristics were recorded. Information about implementation of target guideline recommendations (smoking cessation, pulmonary rehabilitation referral, influenza vaccination, medication use and long-term oxygen use if hypoxaemic) was gained from medical records and patient interviews. Interviews with hospital-based doctors examined their perspectives on recommendation implementation.ResultsFifteen patients (aged 76(9) years, FEV1%pred 58(15), mean(SD)) and nine doctors participated. Referral to pulmonary rehabilitation (5/15 patients) was underutilised by comparison with other high-evidence recommendations. Low awareness of pulmonary rehabilitation was a key barrier for patients and doctors. Other barriers for patients were access difficulties, low perceived health benefits, and co-morbidities. Doctors reported they tended to refer patients with severe disease and frequent hospital attendance, a finding supported by the quantitative data.ConclusionsThis study provides justification for a larger observational study to test the hypothesis that pulmonary rehabilitation referral is low in suitable COPD patients, and closer investigation of the reasons for this evidence-practice gap.

Percutaneous biopsy of intrapulmonary mass lesions. Experience with a disposable cutting needle

This study investigated the diagnostic efficacy and safety of a percutaneous core biopsy technique in patients with undiagnosed intrapulmonary mass lesions. Eighty‐four consecutive biopsies were performed in 81 patients with intrapulmonary mass lesions. Follow‐up data permitted a final diagnosis in 79 of these 81 patients, which allowed an assessment of the accuracy of the technique. Fifty‐nine of 68 patients with malignant lesions were diagnosed by core biopsy (87% sensitivity) and nine of 11 with benign lesions (82% sensitivity). The complication rate was 21%. Malignant tumor cell‐type was predicted correctly from biopsy material in 60% of patients. It is concluded that core biopsy is a safe procedure if restricted to the investigation of intrapulmonary mass lesions, and is effective in the identification of malignant tumors. Its chief advantage over aspiration techniques is that the tissue core obtained permits a specific diagnosis in a high proportion of patients with benign lesions, thus reducing the need in these patients for continued observation or diagnostic thoracotomy.