International Consensus Statement on Obstructive Sleep Apnea

BACKGROUND

Evaluation and interpretation of the literature on obstructive sleep apnea (OSA) allows for consolidation and determination of the key factors important for clinical management of the adult OSA patient. Toward this goal, an international collaborative of multidisciplinary experts in sleep apnea evaluation and treatment have produced the International Consensus statement on Obstructive Sleep Apnea (ICS:OSA).

METHODS

Using previously defined methodology, focal topics in OSA were assigned as literature review (LR), evidence-based review (EBR), or evidence-based review with recommendations (EBR-R) formats. Each topic incorporated the available and relevant evidence which was summarized and graded on study quality. Each topic and section underwent iterative review and the ICS:OSA was created and reviewed by all authors for consensus.

RESULTS

The ICS:OSA addresses OSA syndrome definitions, pathophysiology, epidemiology, risk factors for disease, screening methods, diagnostic testing types, multiple treatment modalities, and effects of OSA treatment on multiple OSA-associated comorbidities. Specific focus on outcomes with positive airway pressure (PAP) and surgical treatments were evaluated.

CONCLUSION

This review of the literature consolidates the available knowledge and identifies the limitations of the current evidence on OSA. This effort aims to create a resource for OSA evidence-based practice and identify future research needs. Knowledge gaps and research opportunities include improving the metrics of OSA disease, determining the optimal OSA screening paradigms, developing strategies for PAP adherence and longitudinal care, enhancing selection of PAP alternatives and surgery, understanding health risk outcomes, and translating evidence into individualized approaches to therapy.

Work-Related Sleep Disorders: Causes and Impacts

Insufficient sleep syndrome, shift work disorder, and obstructive sleep apnea (OSA) not only significantly impact the health of affected individuals, but also pose a threat to public safety. This article describes the clinical manifestations and impact of these sleep disorders, particularly as they pertain to workers' health and those with safety-sensitive positions. Sleep deprivation, circadian rhythm disruptions, and excessive daytime sleepiness-hallmarks of insufficient sleep, shift work disorder, and OSA, respectively-all lead to a series of cognitive deficits and impaired concentration that affect workers in a wide variety of fields. We describe the health consequences of these disorders along with treatment strategies, with a focus on current regulatory standards and the under-recognition of OSA in commercial drivers. Given its large scale, there is a need for improved guidelines and regulations for the screening, diagnosis, treatment, and long-term follow-up of OSA in commercial motor vehicle drivers. Increased recognition of the ways in which these sleep disorders impact workers will pave the way for significant improvements in occupational health and safety.

The distribution of acquired peripheral nerve injuries associated with severe COVID-19 implicate a mechanism of entrapment neuropathy: a multicenter case series and clinical feasibility study of a wearable, wireless pressure sensor

We diagnosed 66 peripheral nerve injuries in 34 patients who survived severe coronavirus disease 2019 (COVID-19). We combine this new data with published case series re-analyzed here (117 nerve injuries; 58 patients) to provide a comprehensive accounting of lesion sites. The most common are ulnar (25.1%), common fibular (15.8%), sciatic (13.1%), median (9.8%), brachial plexus (8.7%) and radial (8.2%) nerves at sites known to be vulnerable to mechanical loading. Protection of peripheral nerves should be prioritized in the care of COVID-19 patients. To this end, we report proof of concept data of the feasibility for a wearable, wireless pressure sensor to provide real time monitoring in the intensive care unit setting.

The COVID-19 pandemic and sleep medicine: a look back and a look ahead

The COVID-19 pandemic is a reminder that global infectious disease outbreaks are not new, and they have the potential to cause catastrophic morbidity and mortality, disrupt health care delivery, demand critical decision-making in the absence of scientific certainty, interrupt trainee education, inflict economic damage, and cause a spike in demand for health care services that exceeds societal capacity. In this document, we look back at how the sleep medicine community adapted to challenges imposed by the COVID-19 pandemic. To mitigate viral transmission, perhaps the single most effective and efficient adaptation was the rapid adoption of telemedicine. Many additional strategies were taken up virtually overnight, including more home sleep apnea testing, reconsideration of potential risks of positive airway pressure therapy, a reduction or cessation of laboratory services, and deployment of workers to provide front-line care to infected patients. During some periods, critical shortages in essential personal protective equipment, respiratory assist devices, and even oxygen added to logistical challenges, which were exacerbated by persistent financial threats and insufficient staffing. Through ongoing innovation, resiliency and adaptability, breakthroughs were made in assigning staff responsibilities and designing workflows, the use of clinical spaces, legislative support, and in professional society collaboration and guidance so that the missions of health care, teaching and academic pursuit could continue. Here we summarize what we have learned through these critical months and highlight key adaptations that deserve to be embraced as we move forward.

Diaphragm and Phrenic Nerve Ultrasound in COVID-19 Patients and Beyond: Imaging Technique, Findings, and Clinical Applications

The diaphragm, the principle muscle of inspiration, is an under-recognized contributor to respiratory disease. Dysfunction of the diaphragm can occur secondary to lung disease, prolonged ventilation, phrenic nerve injury, neuromuscular disease, and central nervous system pathology. In light of the global pandemic of coronavirus disease 2019 (COVID-19), there has been growing interest in the utility of ultrasound for evaluation of respiratory symptoms including lung and diaphragm sonography. Diaphragm ultrasound can be utilized to diagnose diaphragm dysfunction, assess severity of dysfunction, and monitor disease progression. This article reviews diaphragm and phrenic nerve ultrasound and describes clinical applications in the context of COVID-19.

Optimal Noninvasive Medicare Access Promotion: Patients with Thoracic Restrictive Diseases A Technical Expert Panel Report from the American College of Chest Physicians, the American Association for Respiratory Care, the American Academy of Sleep Medicine, and the American Thoracic Society

The existing coverage criteria for Non-Invasive Ventilation (NIV) do not recognize the benefits of early initiation of NIV for those with Thoracic Restrictive Disease (TRD) and do not address the unique needs for daytime support as the patient's progress to ventilator dependence. This document summarizes the work of the Thoracic Restrictive Disease Technical Expert Panel working group. The most pressing current coverage barriers identified were: 1) Delays in implementing NIV treatment 2) Lack of coverage for many non-progressive Neuro-Muscular Disease (NMD) and 3) Lack of clear policy indications for Home -Mechanical Ventilation (HMV) Support in TRD. To best address these issues we make the following key recommendations: 1) Given the need to encourage early initiation of NIV with Bi-level Positive Airway Pressure (BPAP) devices, we recommend that symptoms be considered as a reason to initiate therapy even at mildly reduced FVC's.; 2) Broaden CO2 measurements to include surrogates such as transcutaneous, end-tidal or Venous Blood Gas (VBG); 3) Expand the diagnostic category to include Phrenic Nerve injuries and Disorders of Central Drive; 4) Allow a BPAP device to be advanced to an HMV when the VC is <30% or to address severe daytime respiratory symptoms; 5) Provide an additional HMV when the patient is ventilator dependent with use >18 hours/ day. Adoption of these proposed recommendations would result in the right device, at the right time, for the right type of patients with hypoventilation syndromes.

Diaphragm dysfunction in severe COVID-19 as determined by neuromuscular ultrasound

Many survivors from severe coronavirus disease 2019 (COVID-19) suffer from persistent dyspnea and fatigue long after resolution of the active infection. In a cohort of 21 consecutive severe post-COVID-19 survivors admitted to an inpatient rehabilitation hospital, 16 (76%) of them had at least one sonographic abnormality of diaphragm muscle structure or function. This corresponded to a significant reduction in diaphragm muscle contractility as represented by thickening ratio (muscle thickness at maximal inspiration/end-expiration) for the post-COVID-19 compared to non-COVID-19 cohorts. These findings may shed new light on neuromuscular respiratory dysfunction as a contributor to prolonged functional impairments after hospitalization for post-COVID-19.

TECPR2 mutation-associated respiratory dysregulation: more than central apnea

None

Children with rare genetic diseases that cause respiratory dysregulation are at particularly high mortality risk due to development of respiratory failure. The tectonin β-propeller-containing protein 2 (TECPR2) mutations are proposed to cause autophagy defect affecting axonal integrity and development of progressive neurodegenerative and neuromuscular disease. Published TECPR2 mutation cases have described a high prevalence of respiratory failure. We review respiratory pathology in previously published cases and a new case of a 5-year-old girl with previously undescribed TECPR2 mutation demonstrating progressive central apnea due to respiratory cycle dysregulation. This is the first TECPR2 mutation case to demonstrate an ataxic (Biot's) breathing pattern with consistently inconsistent inspiratory and expiratory times and with relatively intact chemoreception during sleep. Therefore, we propose that the central apnea index alone may not be the appropriate marker for mortality risk. Rather, the morbidity and mortality associated with TECPR2 mutations are multisystem in nature and this burden complicates the ultimate needs for ventilation support and prognosis.

Extubating to Noninvasive Ventilation: Noninvasive Ventilation from Intensive Care Unit to Home

Weaning to noninvasive ventilation in intensive care unit and bridging the patients to home with respiratory support is evolving as the technology of noninvasive ventilation is improving. In patients with chronic obstructive pulmonary disease exacerbation, timing of initiation of noninvasive ventilation is the key, as persistently hypercapnic patients show benefits. High-intensity pressure support seems to do better in comparison to low-intensity pressure support. In patients with obesity and hypercapnia, obesity hypoventilation cannot be ruled out especially in an inpatient setting, and it is crucial that these patients are discharged with noninvasive ventilation.

Sleep disordered breathing in Marfan syndrome: Value of standard screening questionnaires

Background

A high prevalence of sleep disordered breathing (SDB) has been reported in persons with Marfan syndrome (MFS), a single gene disorder of connective tissue resulting in premature death from aortic rupture. The burden of SDB and accompanying hemodynamic stress could warrant broad screening in this population. Our goal was to assess the utility of traditional SDB screening tools in our sample of persons with MFS.

Methods

Participants were recruited during an annual Marfan Foundation meeting and Marfan status confirmed using the Ghent criteria. Screening questionnaires were administered and SDB assessed by home sleep testing. We assessed accuracy of screening tools using receiver‐operating characteristic curve analyses.

Results

The prevalence of moderate‐severe SDB was 32% in our sample of 31 MFS participants. The Stop‐Bang questionnaire had the highest positive predictive value (PPV) of 60% and the highest negative predictive value (NPV) of 100% using the high‐ and moderate‐risk cut‐offs, respectively, and the Berlin questionnaire had a PPV of 50% and an NPV of 92.3% at the high‐risk cut‐off. When those with mild SDB were included, the Stop‐Bang and the Sleep Apnea Clinical Score (SACS) questionnaires demonstrated useful screening accuracies with PPVs of 94.7% and 92.9%, and NPVs of 63.6% and 47.1%, respectively, at the moderate‐risk cut‐offs.

Conclusion

A survey of SDB in a sample of persons with MFS reveals not only a high burden of SDB but also that conventional screening instruments have utility if adapted appropriately. Future studies should validate the utility of these screening tools given concerns that SDB may contribute to progression of aortic pathology in MFS.

Automatic EPAP intelligent volume-assured pressure support is effective in patients with chronic respiratory failure: A randomized trial

BACKGROUND AND OBJECTIVE

Patients with chronic respiratory failure are increasingly managed with domiciliary non-invasive ventilation (NIV). There may be limited ability to provide NIV titration for these complex patients, and ventilatory requirements and upper airway support needs may change over time. Therefore, an automatically adjusting expiratory positive airway pressure (AutoEPAP) algorithm may offer advantages over manually adjusted EPAP for treating these patients. This study compared 4% oxygen desaturation index (ODI4%) values during the use of an AutoEPAP algorithm versus manual EPAP titration with the intelligent volume-assured pressure support (iVAPS) algorithm.

METHODS

This prospective, single-blind, randomized, crossover study was conducted at six US sites. Patients with chronic respiratory failure (neuromuscular disease, chronic obstructive pulmonary disease, obesity hypoventilation and other aetiologies) and an apnoea-hypopnoea index of >5/h who were already established NIV users underwent a single night of NIV with the iVAPS manual EPAP and iVAPS AutoEPAP in the sleep laboratory in random order.

RESULTS

A total of 38 patients constituted the study population. Mean ODI4% was statistically non-inferior with AutoEPAP versus manual EPAP (P < 0.0001). There was no difference in the effect on ODI4% across respiratory failure subgroups. Ventilation parameters and gas exchange were similar with either NIV mode, indicating equally effective treatment of respiratory failure. Sleep parameters were improved during AutoEPAP versus manual EPAP.

CONCLUSION

A single night of NIV using the iVAPS with AutoEPAP algorithm was non-inferior to a single night of iVAPS with manual EPAP titration in patients with respiratory failure.

CLINICAL TRIAL REGISTRATION

NCT02683772 at clinicaltrials.gov.

Sleep disorders in traumatic brain injury

BACKGROUND

Sleep disorders play a significant role in the care of those with Traumatic Brain Injury (TBI).

OBJECTIVE

To provide a literature review on the interaction of sleep and circadian processes on those with TBI.

METHODS

A literature review was conducted on PubMed using the following key words and their combination: "Sleep Apnea", "Traumatic Brain Injury", "Circadian", "Parasomnia", "Insomnia", "Hypersomnia", "Narcolepsy", and "Restless Legs". We review the spectrum of traumatic brain injury associated sleep disorders and discuss clinical approaches to diagnosis and treatment.

RESULTS

Disordered sleep and wakefulness after TBI is common. Sleep disruption contributes to morbidity, such as the development of neurocognitive and neurobehavioral deficits, and prolongs the recovery phase after injury. Early recognition and correction of these problems may limit the secondary effects of traumatic brain injury and improve neuro recovery/patient outcomes.

CONCLUSIONS

A more focused approach to sleep health is appropriate when caring for those with TBI.

Respiratory Management of the Patient With Duchenne Muscular Dystrophy

In 2010, Care Considerations for Duchenne Muscular Dystrophy, sponsored by the Centers for Disease Control and Prevention, was published in Lancet Neurology, and in 2018, these guidelines were updated. Since the publication of the first set of guidelines, survival of individuals with Duchenne muscular dystrophy has increased. With contemporary medical management, survival often extends into the fourth decade of life and beyond. Effective transition of respiratory care from pediatric to adult medicine is vital to optimize patient safety, prognosis, and quality of life. With genetic and other emerging drug therapies in development, standardization of care is necessary to accurately assess treatment effects in clinical trials. This revision of respiratory recommendations preserves a fundamental strength of the original guidelines: namely, reliance on a limited number of respiratory tests to guide patient assessment and management. A progressive therapeutic strategy is presented that includes lung volume recruitment, assisted coughing, and assisted ventilation (initially nocturnally, with the subsequent addition of daytime ventilation for progressive respiratory failure). This revision also stresses the need for serial monitoring of respiratory muscle strength to characterize an individual's respiratory phenotype of severity as well as provide baseline assessments for clinical trials. Clinical controversies and emerging areas are included.

Phase Relationship between DLMO and Sleep Onset and the Risk of Metabolic Disease among Normal Weight and Overweight/Obese Adults

Circadian misalignment is hypothesized to contribute to increased diabetes and obesity among shift workers and individuals with late sleep timing. Accordingly, the goal of our study was to identify-among normal and overweight/obese adults-associations between circadian timing (dim light melatonin onset; DLMO) and circadian misalignment (the interval between DLMO and sleep onset) with metabolic disease risk. This was a secondary analysis of data from a larger study. Participants ages 18 to 50 years without depression, diabetes, or shift work, with sleep duration 6.5 h or more, completed the following evaluations: 7 days of wrist actigraphy, circadian timing assessment (DLMO), and a fasting blood draw to measure glucose and insulin and calculate the Homeostatic Model of Assessment-Insulin Resistance (HOMA-IR). Data were analyzed using correlation and regression analyses controlling for age, sex, DLMO, and sleep duration. Analyses were conducted for the entire sample ( n = 54) and stratified by normal weight ( n = 36) and overweight/obese groups ( n = 18). Mean age was 26.4 years (SD = 7.1 years). Average sleep duration was 436.2 min (SD = 55.1 min), DLMO was 2250h (SD = 01:31), and interval between DLMO and sleep onset was 2 h 18 min (SD = 53 min). Average BMI was 24.3 kg/m² (SD = 4.5 kg/m²). Circadian timing and interval between DLMO and sleep onset were not associated with glucose, insulin, or HOMA-IR in the main analyses. Among overweight/obese participants, a shorter interval between DLMO and sleep onset was associated with higher insulin ( B[SE] = -5.12 [2.24], p = 0.04) and HOMA-IR ( B[SE] = -1.32 [0.57], p = 0.04). Results of our multivariable model indicated that among overweight/obese participants, insulin was 5.1 pmol/L higher and HOMA was 1.3 µU/mL higher for every hour closer that sleep onset was to DLMO. The strengths of this study include the use of objective measures of circadian timing, but results should be considered hypothesis generating due to the small sample size and use of subgroup analyses.

Stability of Melatonin and Temperature as Circadian Phase Markers and Their Relation to Sleep Times in Humans

Circadian rhythms of core body temperature and melatonin are commonly used as phase markers of the circadian clock. Melatonin is a more stable marker of circadian phase when measured under constant routine conditions. However, little is known about the variability of these phase markers under less controlled conditions. Moreover, there is little consensus about the preferred method of analysis. The objective of this study was to assess various methods of calculating melatonin and temperature phase in subjects with regular sleep schedules living in their natural environment. Baseline data were analyzed from 42 healthy young subjects who were studied on at least two occasions. Each hospital admission was separated by at least 3 weeks. Subjects were instructedto maintain a regular sleep schedule, which was monitored for 1 week before admission by sleep logs and actigraphy. Subjects spent one habituation night under controlled conditions prior to collecting baseline temperature and melatonin measurements. The phase of the melatonin rhythm was assessed by 9 different methods. The temperature nadir (Tmin) was estimated using both Cleveland and Cosine curve fitting procedures, with and without demasking. Variability between admissions was assessed by correlation analysis and by the mean absolute difference in timing of the phase estimates. The relationship to sleep times was assessed by correlation of sleep onset or sleep offset with the various phase markers. Melatonin phase markers were more stable and more highly correlated with the timing of sleep than estimates of Tmin. Of the methods for estimating Tmin, simple cosine analysis was the least variable. In addition, sleep offset was more strongly correlated with the various phase markers than sleep onset. The relative measures of melatonin offset had the highest correlation coefficients, the lowest study-to-study variability, and were more strongly associated with sleep timing than melatonin onsets. Concordance of the methods of analysis suggests a tendency for the declining phase of the melatonin profile to be more stable and reliable than either markers of melatonin onset or measures of the termination of melatonin synthesis.

The role of noninvasive ventilation in the management and mitigation of exacerbations and hospital admissions/readmissions for the patient with moderate to severe COPD (multimedia activity)

As seen in this CME online activity (available at http://journal.cme.chestnet.org/home-niv-copd), COPD is a common and debilitating disease and is currently the third leading cause of death in the United States. The role of noninvasive ventilation (NIV) in the management of severe, hypercapnic COPD has been controversial. However, it was concluded that current data would support the following recommendations. Patients with COPD with a waking Paco2 > 50 to 52 mm Hg, an overnight Paco2 > 55 mm Hg, or both who are symptomatic and compliant with other therapies should be eligible for NIV. In addition, multiple previous hospital admissions for COPD exacerbation, requiring noninvasive/invasive mechanical ventilation, strongly suggest a need for chronic NIV. Patients with COPD with a BMI > 30 kg/m2 respond particularly well to this therapy. When the decision is made to start NIV, this treatment is probably best initiated during a short hospitalization, although this can be accomplished in the clinic, home, or sleep laboratory if well-trained clinicians are available. Newer modes of NIV such as volume-assured pressure support, particularly with autotitrating expiratory positive airway pressure (EPAP), may create the opportunity for home NIV initiation easier for less experienced physicians. Regardless of the mode selected, inspiratory pressures must be in the 20 to 25 cm H2O range to meaningfully increase tidal volume, reduce work of breathing, and, importantly, reduce waking arterial Paco2. EPAP is currently set at 4 to 5 cm H2O, although future technologies may allow this to be individualized to maximally reduce auto-positive end expiratory pressure. The NIV device should have a backup rate although it is controversial as to whether this should be set at a high (18-20 breaths/min) vs a low (8-10 breaths/min) rate. The proper use of NIV in appropriately chosen patients with COPD can improve quality of life and increase survival. Ongoing studies are assessing if the frequency of future hospitalizations can be reduced with NIV. Thus, NIV should be strongly considered in any patients with COPD meeting the criteria described here.

The changing landscape of adult home noninvasive ventilation technology, use, and reimbursement in the United States

There has been an exponential increase in the use of home noninvasive ventilation (NIV). Despite growing use, there is a paucity of evidence-based guidelines and practice standards in the United States to assist clinicians in the initiation and ongoing management of home NIV. Consequently, home NIV practices are being influenced by complicated local reimbursement policies and coding. This article aims to provide a practice management perspective for clinicians providing home NIV, including Local Coverage Determination reimbursement criteria for respiratory assist devices, Durable Medical Equipment coding, and Current Procedural Terminology coding to optimize clinical care and minimize lost revenue. It highlights the need for further research and development of evidence-based clinical practice standards to ensure best practice policies are in place for this rapidly evolving patient population.

The complex sleep apnea resolution study: a prospective randomized controlled trial of continuous positive airway pressure versus adaptive servoventilation therapy

INTRODUCTION

Prior studies show that adaptive servoventilation (ASV) is initially more effective than continuous positive airway pressure (CPAP) for patients with complex sleep apnea syndrome (CompSAS), but choosing therapies has been controversial because residual central breathing events may resolve over time in many patients receiving chronic CPAP therapy. We conducted a multicenter, randomized, prospective trial comparing clinical and polysomnographic outcomes over prolonged treatment of patients with CompSAS, with CPAP versus ASV.

METHODS

Qualifying participants meeting criteria for CompSAS were randomized to optimized CPAP or ASV treatment. Clinical and polysomnographic data were obtained at baseline and after 90 days of therapy.

RESULTS

We randomized 66 participants (33 to each treatment). At baseline, the diagnostic apnea-hypopnea index (AHI) was 37.7 ± 27.8 (central apnea index [CAI] = 3.2 ± 5.8) and best CPAP AHI was 37.0 ± 24.9 (CAI 29.7 ± 25.0). After second-night treatment titration, the AHI was 4.7 ± 8.1 (CAI = 1.1 ± 3.7) on ASV and 14.1 ± 20.7 (CAI = 8.8 ± 16.3) on CPAP (P ≤ 0.0003). At 90 days, the ASV versus CPAP AHI was 4.4 ± 9.6 versus 9.9 ± 11.1 (P = 0.0024) and CAI was 0.7 ± 3.4 versus 4.8 ± 6.4 (P < 0.0001), respectively. In the intention-to-treat analysis, success (AHI < 10) at 90 days of therapy was achieved in 89.7% versus 64.5% of participants treated with ASV and CPAP, respectively (P = 0.0214). Compliance and changes in Epworth Sleepiness Scale and Sleep Apnea Quality of Life Index were not significantly different between treatment groups.

CONCLUSION

Adaptive servoventilation (ASV) was more reliably effective than CPAP in relieving complex sleep apnea syndrome. While two thirds of participants experienced success with CPAP, approximately 90% experienced success with ASV. Because both methods produced similar symptomatic changes, it is unclear if this polysomnographic effectiveness may translate into other desired outcomes.

CLINICAL TRIALS

Clinicaltrials.Gov NCT00915499.

Phase-shifting response to light in older adults

Age-related changes in circadian rhythms may contribute to the sleep disruption observed in older adults. A reduction in responsiveness to photic stimuli in the circadian timing system has been hypothesized as a possible reason for the advanced circadian phase in older adults. This project compared phase-shifting responses to 2 h of broad-spectrum white light at moderate and high intensities in younger and older adults. Subjects included 29 healthy young (25.1 ± 4.1 years; male to female ratio: 8: 21) and 16 healthy older (66.5 ± 6.0 years; male to female ratio: 5: 11) subjects, who participated in two 4-night and 3-day laboratory stays, separated by at least 3 weeks. Subjects were randomly assigned to one of three different time-points, 8 h before (-8), 3 h before (-3) or 3 h after (+3) the core body temperature minimum (CBTmin) measured on the baseline night. For each condition, subjects were exposed in a randomized order to 2 h light pulses of two intensities (2000 lux and 8000 lux) during the two different laboratory stays. Phase shifts were analysed according to the time of melatonin midpoint on the nights before and after light exposure. Older subjects in this study showed an earlier baseline phase and lower amplitude of melatonin rhythm compared to younger subjects, but there was no evidence of age-related changes in the magnitude or direction of phase shifts of melatonin midpoint in response to 2 h of light at either 2000 lux or 8000 lux. These results indicate that the acute phase-shifting response to moderate- or high-intensity broad spectrum light is not significantly affected by age.

Management of pulmonary complications in neuromuscular disease

Restrictive lung disease occurs commonly in patients with neuromuscular disease. The earliest sign of respiratory compromise in the patient with neuromuscular disease is nocturnal hypoventilation, which progresses over time to include daytime hypoventilation and eventually the need for full-time mechanical ventilation. Pulmonary function testing should be done during regular follow-up visits to identify the need for assistive respiratory equipment and initiate early noninvasive ventilation. Initiation of noninvasive ventilation can improve quality of life and prolong survival in patients with neuromuscular disease.

Light-induced changes of the circadian clock of humans: increasing duration is more effective than increasing light intensity

STUDY OBJECTIVES

To evaluate the effect of increasing the intensity and/or duration of exposure on light-induced changes in the timing of the circadian clock of humans.

DESIGN

Multifactorial randomized controlled trial, between and within subject design

SETTING

General Clinical Research Center (GCRC) of an academic medical center

PARTICIPANTS

56 healthy young subjects (20-40 years of age)

INTERVENTIONS

Research subjects were admitted for 2 independent stays of 4 nights/3 days for treatment with bright or dim-light (randomized order) at a time known to induce phase delays in circadian timing. The intensity and duration of the bright light were determined by random assignment to one of 9 treatment conditions (duration of 1, 2, or 3 hours at 2000, 4000, or 8000 lux).

MEASUREMENTS AND RESULTS

Treatment-induced changes in the dim light melatonin onset (DLMO) and dim light melatonin offset (DLMOff) were measured from blood samples collected every 20-30 min throughout baseline and post-treatment nights. Comparison by multi-factor analysis of variance (ANOVA) of light-induced changes in the time of the circadian melatonin rhythm for the 9 conditions revealed that changing the duration of the light exposure from 1 to 3 h increased the magnitude of light-induced delays. In contrast, increasing from moderate (2,000 lux) to high (8,000 lux) intensity light did not alter the magnitude of phase delays of the circadian melatonin rhythm.

CONCLUSIONS

Results from the present study suggest that for phototherapy of circadian rhythm sleep disorders in humans, a longer period of moderate intensity light may be more effective than a shorter exposure period of high intensity light.

Hyperinflation is associated with lower sleep efficiency in COPD with co-existent obstructive sleep apnea

Prior research has shown that individuals with obstructive lung disease are at risk for sleep fragmentation and poor sleep quality. We postulated that patients with chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (known as overlap syndrome) who have more severe lung disease, as measured by lung hyperinflation (inspiratory capacity/total lung capacity), would have greater sleep disturbances independent of traditional measures of sleep apnea. We performed a retrospective chart review of consecutive patients evaluated and treated in an academic pulmonary clinic for overlap syndrome. Pulmonary function tests and polysomnogram data were collected. Thirty patients with overlap syndrome were included in the analysis. We found significant univariable associations between sleep efficiency and apnea/hypopnea index (beta = -0.285, p = 0.01) and between sleep efficiency and lung hyperinflation (beta = 0.654, p = 0.03). Using multivariable linear regression, the relationship between sleep efficiency and lung hyperinflation remained significant (beta = 1.13, p = 0.02) after adjusting for age, sex, body mass index, apnea/hypopnea index, FEV(1)% predicted, oxygen saturation nadir, medications, and cardiac disease. We conclude that increased severity of hyperinflation is associated with worse sleep efficiency, independent of apnea and nocturnal hypoxemia. The mechanisms underlying this observation are uncertain. We speculate that therapies aimed at reducing lung hyperinflation may improve sleep quality in patients with overlap syndrome.

Effect of an angiotensin II receptor blocker and two angiotensin converting enzyme inhibitors on transforming growth factor-beta (TGF-beta) and alpha-actomyosin (alpha SMA), important mediators of radiation-induced pneumopathy and lung fibrosis

Progressive, irreversible fibrosis is one of the most clinically significant consequences of ionizing radiation on normal tissue. When applied to lungs, it leads to a complication described as idiopathic pneumonia syndrome (IPS) and eventually to organ fibrosis. For its high mortality, the condition precludes treatment with high doses of radiation. There is widespread interest to understand the pathogenetic mechanisms of IPS and to find drugs effective in the prevention of its development. This report summarizes our experience with the protective effects of L 158,809, an angiotensin II (ANG II) receptor blocker, and two angiotensin converting enzyme (ACE) inhibitors in the development of IPS and the role of transforming growth factor beta (TGF-beta) and of alpha-actomyosin (alpha SMA) in pathogenesis of radiation induced pulmonary fibrosis in an experimental model of bone marrow transplant (BMT). Male WAG/Riji/MCV rats received total body irradiation and a regimen of cyclophosphamide (CTX) in preparation for bone marrow transplant. While one group of animals remained untreated, the remainders were subdivided into three groups, each of them receiving either the ANG II receptor blocker or one of the two ACE inhibitors (Captopril or Enalapril). Each of the three drugs was administered orally from 11 days before the transplant up to 56 days post transplant. At sacrifice time the irradiated rats receiving only CTX showed a chronic pneumonitis with septal fibrosis and vasculitis affecting, in particular, small caliber pulmonary arteries and arterioles. Their lung content of hydroxyproline was also markedly elevated in association with the lung concentrations of thromboxane (TXA2) and prostaglandin (PGI(2)), (two markers of pulmonary endothelial damage). A significant increase of alpha actomyosin staining was observed in vessels, septa and macrophages of the same animals which also overexpressed TGF-beta. When L 158,809, Captopril and Enalapril were added to the radiation and cytoxan treatment, a significant amelioration of the histological damage as well as the overexpression of alpha SMA was observed. Lung concentrations of hydroxyproline, PGI(2), TXA2 and TGF-beta were also observed in these animals so that the values of these compounds were closer to those measured in untreated control rats than to their irradiated and cytoxan treated counterparts. Angiotensin II plays an important role in the regulation of TGF-beta and alpha SMA, two proteins involved in the pathogenesis of pulmonary fibrosis. The finding that ACE inhibitors or ANG II receptor blockers protect the lungs from radiation induced pneumonitis and fibrosis reaffirms the role that ANG II plays in this inflammatory process and suggests an additional indication of treatment of this condition, thus opening a new potential pharmacologic use of these drugs.

Circadian phase-shifting effects of nocturnal exercise in older compared with young adults

Exercise can phase shift the circadian rhythms of young adults if performed at the right time of day. Similar research has not been done in older adults. This study examined the circadian phase-delaying effects of a single 3-h bout of low-intensity nocturnal exercise in older (n = 8; 55-73 yr old) vs. young (n = 8; 20-32 yr old) adults. The exercise occurred at the beginning of each subject's habitual sleep time, and subjects sat in a chair in dim light during the corresponding time in the control condition. The dim-light melatonin onset (DLMO) was used as the circadian phase marker. The DLMO phase delayed more after the exercise than after the control condition. On average, the difference in phase shift between the exercise and control conditions was similar for older and young subjects, demonstrating that the phase-shifting effects of exercise on the circadian system are preserved in older adults. Therefore, exercise may potentially be a useful treatment to help adjust circadian rhythms in older and young adults.

Prevention of radiation-induced nephropathy and fibrosis in a model of bone marrow transplant by an angiotensin II receptor blocker

Nephropathy, interstitial pneumopathy, and renal and lung fibrosis are major complications of bone marrow transplantation (BMT). This study evaluated the antifibrotic property of an angiotensin II (A2) type-1 receptor blocker (L-159,809) and compared it with those of Captopril and Enalapril, two angiotensin-converting enzyme (ACE) inhibitors, in a rat model of BMT. Male WAG/Rij/MCW rats received a preparative regimen of 60 mg/kg body wt of cytoxan (i.p., Days 9 and 8) and 18.5 Gy of total body irradiation (TBI) in six twice daily fractions (Days 2, 1, and 0) followed immediately (Day 0) by BMT. Modifiers were given in drinking water from Day 10 until autopsy, 8 weeks after BMT. Rats treated with TBI plus cytoxan alone developed severe nephropathy. Trichrome staining showed marked collagen deposition in glomeruli, renal interstitium, and renal arteries and arterioles (especially in their adventitia). Collagen deposition and renal damage were markedly reduced by the three modifiers. Of the three, L-158,809-treated rats had slightly thinner vessels and slightly less collagen than nonirradiated normal controls. The study shows the effectiveness of these drugs in the protection of the renal parenchyma from the development of radiation-induced fibrosis. It also indicates a role for angiotensin II in the modulation of collagen synthesis.

Control of radiation-induced pneumopathy and lung fibrosis by angiotensin-converting enzyme inhibitors and an angiotensin II type 1 receptor blocker

PURPOSE

This report summarizes our experiences on the protective effect of angiotensin-converting enzyme (ACE) inhibitors, especially captopril and an angiotensin II type 1 receptor blocker on radiation-induced pulmonary injury.

METHOD

In the first series of experiments, adult male Sprague Dawley rats were given a single dose of either 20 or 30 Gy of gamma rays to a 35 cm2 right hemithorax port, whilst shielding the left, contralateral, lung. Perfusion scans and autopsies were performed at intervals up to 12 months post-radiation. Three different ACE inhibitors, penicillamine and pentoxifylline were given as radiation protectors and their activity compared. A model of irradiation for total bone marrow transplant (BMT) was used for the second group of experiments. Male WAC/Rij/MCW rats received total-body irradiation and a regimen of cyclophosphamide (CTX) in preparation for bone marrow transplant. The modifiers were two ACE inhibitors, captopril and enalapril, and L-158,809, an angiotensin II (A II) type 1 receptor blocker. All drugs were administered in the rats' drinking water and all were well-tolerated.

RESULTS

In the irradiated rats, pulmonary damage progressed from the presence of blebs and detachment from basement membranes of endothelial cells a few days after injury, to severe arteritis and interstitial collagen deposition at 3 months, and then on to severe pneumonitis and extensive pulmonary fibrosis at 6 months. Marked increase of hydroxyproline was also found in the lungs at 6 months. These morphological changes were associated with significant decrease of ACE and plasminogen activator activity (PLA) and a marked increase of prostaglandins (PG12) and thromboxane (Txa2), substances considered as indicators of endothelial pulmonary damage. ACE inhibitors captopril, CL 24817, enalapril and CGS 13945 prevented the markers of endothelial dysfunction. Captopril and CL 24817, which contain a sulphydryl (-SH) radical in their moiety and the AII type 1 receptor blocker, L-158,809, were the most efficient in protecting the lung parenchyma from the inflammatory response and subsequent fibrosis. Penicillamine, an SH-containing compound with weak ACE inhibitory activity was also a strong antifibrotic agent but showed only modest anti-inflammatory properties. Additionally, in the irradiated rats, captopril also reduced the incidence of squamous cell skin carcinomas and subcutaneous sarcomas consequent to the highest doses of radiation.

CONCLUSION

ACE inhibitors and one AII type 1 receptor blocker were effective in protecting lungs from radiation-induced pneumonitis and the development of lung fibrosis in two models of rat radiation injury. In the first series of experiments (unilateral irradiation), those ACE inhibitors containing a sulphydryl radical were more effective than those without it. This observation led to the question of whether this protective effect is related to inhibition of AII synthesis or rather to some of the collateral pharmacologic properties of these drugs, such as anti-oxidation or protease inhibition. The AII receptor blocker, however, was shown to be equally effective, if not better, in its antifibrotic capacity than any ACE inhibitor with or without an SH radical, reaffirming the role of AII in modulation of collagen synthesis.