| Current
Respiratory Medicine Reviews
ISSN: 1573-398X
Current Respiratory Medicine
Reviews
Volume 3, Number 4, November 2007
Contents
Sleep Medicine
Guest Editor: Salim Surani
Editorial Pp. 240
Obstructive Sleep Apnea and Stroke Pp. 241-244
Philip M. Alapat
[Abstract]
Perioperative Considerations in Patients with Obstructive
Sleep Apnea Pp. 245-253
Dennis Auckley, Norman Bolden and Charles E. Smith
[Abstract]
Positive Airway Pressure in Sleep Disordered Breathing
Pp. 254-257
Nisha K. Rathi, Mary Rose and Diwakar Balachandran
[Abstract]
Sleep-Disordered Breathing and Cardiovascular Disease:
Exploring Pathophysiology and Existing Data Pp. 258-269
Reena Mehra
[Abstract]
Sleep Disordered Breathing: Alternatives to CPAP Therapy
Pp. 270-277
Akram Khan and Kannan Ramar
[Abstract]
Polycystic Ovarian Syndrome and Obstructive Sleep
Apnea Pp. 278-281
Ashesh Desai and Shyam Subramanian
[Abstract]
Depression in Sleep Related Breathing Disorder
Pp. 282-285
Shyam Subramanian, Mary Rose and Salim Surani
[Abstract]
Sleep Related Disorders in the Elderly: An Overview
Pp. 286-291
Salim Surani and Alamgir Khan
[Abstract]
Association of Sleep Apnea Syndrome and Diabetes Mellitus
Pp. 292-296
Salim Surani and Joseph Varon
[Abstract]
General Reviews
Airway Remodeling: Effect of Current and Future Asthma
Therapies Pp. 297-308
Janette K. Burgess and Lyn M. Moir
[Abstract]
Neurologic Sequelae in Critical Illness: Evaluation
and Outcomes Pp. 309-319
Mary R. Suchyta and Ramona O. Hopkins
[Abstract]
Abstracts
[Back to top]
Editorial
For the last 20 years sleep medicine has been recognized as
a separate clinical specialty. Pulmonary physicians first
became involved in the arena of sleep medicine as obstructive
sleep apnea and sleep related breathing disorders were recognized.
Although sleep-disordered breathing had been recognized for
centuries, it was not until recently that close attention
was paid to this clinical entity. Charles Dickens, in 1836,
gave a perfect description of sleep-disordered breathing with
his classic writing about “Joe the fat boy”, now
a synonym of obstructive sleep apnea syndrome (OSAS) [1].
The development of modern Sleep Medicine is closely linked
to the discovery of the electrical activity of the brain.
In 1875 in England Caton was the first to record brain electrical
activity of animals [2]. Berger reported the “electroencephalogram
of man” in Germany in 1929 [3]. In 1937, Loomis was
the first to document the characteristic electroencephalogram
(EEG) patterns of what is now called non rapid eye movement
(NREM) sleep: vertex waves, sleep spindles, K complex, and
Delta slowing [4]. Kleitman, in 1953, described rapid eye
movement sleep (REM) and its correlation with dreaming [5].
In 1957 Dement and Kleitman [6], described the human sleep
cycle of NREM sleep being followed by REM sleep. In 1968,
standardized methods for characterizing normal sleep were
published by Allan Rechtschaffen and Anthony Kales. In 1970,
Guilleminault described obstructive sleep apnea, whereas for
some the beginning was related to Colin Sullivan’s findings
about continuous positive airway pressure therapy (CPAP) in
1981 [7,8]. In 1993 it was Terry Young’s article in
New England Journal of Medicine about the prevalence
of sleep-disordered breathing that led to the advent of the
sleep medicine specialty [9].
The decade of the 1990s saw acceleration in the acceptance
of sleep medicine throughout the world. In the United States,
the National Center on Sleep Disorders Research (NCSDR) was
established by statute as part of the National Heart, Lung,
and Blood Institute of the National Institute of Health (NIH).
Sleep related breathing disorders now appear to involve several
organs and systems. There have been numerous studies published
on the role of sleep related breathing disorder and the cardiovascular
system, diabetes, polycystic ovarian syndrome, peri-operative
assessment, and cerebrovascular accidents. In the current
issue we have attempted to provide a review of some important
correlations of sleep related breathing disorders and their
effects on different organ systems.
REFERENCES
[1] Dickens C. The Pickwick Papers. Penguin Classics. Reprint
of 1836-1837 Edition. London UK: Penguin Books; 1986.
[2] Carlton R. The electric currents of the brain. Br Med
J 1875; 2: 278.
[3] Berger H. Uber das elektroenkephalogramm des menschen.
Arch Psychiatr Nervenkr 1929; 97: 6-26.
[4] Loomis Al, Harvey EN, Hobart GA. Cerebral states during
sleep as studied by human brain potentials. Sci Mon 1937;
45(2): 191-192.
[5] Aserinsky E, Kleitman N. Regularly occurring episodes
of eye mobility and concomitant phenomenon during sleep. Science
1953; 118: 273-274.
[6] Dement WC, Kleitman N. Cyclic variations in EEG during
sleep and their relation to eye movement, body mobility and
dreaming. Electroencephalogr Clin Neurophysiol 1957; 9: 673-690.
[7] Guilleminault C, Dement W. 235 cases of excessive daytime
sleepiness. Diagnosis and tentative classification. J Neurol
Sci 1977; 31: 13-27.
[8] Sullivan CE, Issa FG, Berthon-Jones M, et al.
Reversal of obstructive sleep apnea by continuous airway pressure
applied through the nares. Lancet 1981; 1: 862-865.
[9] Young T, Palta M, Dempsey J, et al. The occurrence
of sleep disordered breathing among middle-aged adults. N
Engl J Med 1993; 328: 1230-1235.
Salim Surani
Texas A&M University
613 Elizabeth Street
Suite 813, Corpus Christi
TX 78413
USA
E-mail: srsurani@hotmail.com
[Back to top]
Obstructive Sleep Apnea and Stroke
Philip M. Alapat
Stroke is one of the leading causes of mortality, and several
risk factors have been identified that may be modified to
ameliorate this risk. Recently, obstructive sleep apnea (OSA)
has been implicated as a possible additional risk factor for
stroke. OSA is a common disorder characterized by repeated
upper airway collapse during sleep leading to multiple physiologic
abnormalities. Several recent studies suggest that OSA is
an independent risk factor for stroke. This independent association
is likely due to derangement of normal sleep physiology and
the attendant consequences to auto-nomic, vascular endothelial,
and thrombotic/fibrinolytic dysfunction leading to the development
of atherosclerosis. Additionally, OSA’s contribution
to the development of known risk factors for stroke such as
hypertension and atrial fibrillation may also predispose a
patient to develop cerebrovascular disease. Patients presenting
with stroke who are also diagnosed with OSA have a worse prognosis
than those without OSA. Therapy with continuous positive airway
pressure (CPAP), the treatment of choice for most patients
with OSA, appears to be beneficial, but achieving compliance
in patients post-stroke is difficult.
[Back to top]
Perioperative Considerations in Patients with Obstructive
Sleep Apnea
Dennis Auckley, Norman Bolden and Charles E. Smith
Patients with obstructive sleep apnea (OSA) are at increased
risk to sustain adverse events during the perioperative period
including difficulty with airway control, hypoxemia, airway
obstruction requiring reintubation, arrhythmias, myocardial
ischemia, and death. Numerous factors appear to be responsible
for these consequences, including the effects of anesthetic
agents, narcotics, postoperative supine positioning and, in
some cases, the surgical intervention itself. The situation
is complicated by the fact that most patients with OSA are
undiagnosed and there is often insufficient time for adequate
evaluation prior to surgery. Perioperative care providers
need to maintain a high index of suspicion for OSA and should
consider guidelines to help with the recognition and management
of these patients. This review will discuss the available
literature regarding the preoperative, intraoperative and
postoperative evaluation and management of patients with known
or suspected OSA undergoing surgery.
[Back to top]
Positive Airway Pressure in Sleep Disordered Breathing
Nisha K. Rathi, Mary Rose and Diwakar Balachandran
Obstructive sleep apnea (OSA) is characterized by repetative
obstruction of the upper airway. Positive airway pressure
has evolved as the preferred therapeutic modality for OSA.
PAP can be used successfully to treat both OSA and central
sleep apnea (CSA). PAP usage affects a variety of medical
diseases. Proper titration and attention to compliance is
paramount in proper usage of PAP. Finally, auto-titrating
devices and adaptive servo ventilation may be used to treat
and possibly diagnose sleep disorder breathing and the later
may have role in treating complex sleep apnea.
[Back to top]
Sleep-Disordered Breathing and Cardiovascular Disease:
Exploring Pathophysiology and Existing Data
Reena Mehra
Sleep-Disordered Breathing (SDB) is characterized by repetitive
partial or complete upper airway occlusion during sleep with
a high prevalence in the general community, and associated
with considerable morbidity and mortality. In the US, approximately
12 million people 30 to 60 years of age have SDB, and 38,000
die each year from cardiovascular disease attributed to SDB.
Substantial morbidity and economic costs are associated with
untreated SDB, including those related to daytime sleepiness
and hypertension, and cardiovascular co-morbidity. There is
a crucial need to address the public health impact of this
common condition, including the extent to which treatment
of SDB may modify the course of other chronic health conditions
such as cardiovascular disease. The public health impact of
SDB in large part relates to the association of SDB with cardiovascular
disease, a leading cause of mortality in the U.S. Several
large epidemiological studies have clearly demonstrated that
individuals with SDB have a higher prevalence of cardiovascular
disease after controlling for potential confounders. These
data, along with the high prevalence of SDB, support a high
population attributable risk, suggesting that a high percentage
of cardiovascular morbidity in the population may be due to
SDB.
[Back to top]
Sleep Disordered Breathing: Alternatives to CPAP Therapy
Akram Khan and Kannan Ramar
Continuous positive airway pressure (CPAP) is the first line
treatment for obstructive sleep apnea (OSA), and resolves
the majority of complications associated with untreated OSA.
However, many patients are unable to tolerate CPAP and may
be offered alternate treatments. Positional therapy is most
helpful in some OSA patients with a low body mass index (BMI).
Both dietary and surgical weight loss are effective in improving
OSA; a 10% weight reduction can decrease AHI by 26%, Oral
appliances (OA) are effective in 57-81% of patients with mild-moderate
OSA. Though oral appliances have a lower success rate (14-61%)
in patients with severe OSA, they may be helpful in patients
who have failed CPAP or upper airway surgery. A follow up
polysomnography and close follow up for dental occlusion changes
is recommended in all patients. Uvulopalatopharyngoplasty
(UPPP) is effective in half (52.3%) of patients with retro-palatal
narrowing, and is effective in a very small proportion of
patients (5.3%) with retro-lingual or both retro-palatal and
retro-lingual narrow-ing. Maxillomandibular osteotomy and
advancement (MMO) enlarges both the retro-lingual and retro-palatal
airway. Patients with normal BMI’s and skeletal abnormalities
are most likely to benefit from it. A follow up polysomnography
is recommended after upper airway surgery. Palatal implants
need to be studied further before they can be considered a
mainstream treatment. Improvement in nasal patency with intranasal
corticosteroids and treatment of residual daytime sleepiness
with modafinil may be beneficial in some patients.
[Back to top]
Polycystic Ovarian Syndrome and Obstructive Sleep
Apnea
Ashesh Desai and Shyam Subramanian
Polycystic ovarian syndrome (PCOS) is a clinical syndrome
characterized by irregular menstrual cycles, signs of androgen
access including hirsutism and acne, and infertility, with
ovaries showing cystic changes. Many women with this condition
are obese, and it is now well established that insulin resistance
makes up a very important component of this syndrome. Recently,
there has been increased focus on sleep-disordered breathing
(SDB) in patients with PCOS. Several articles recently published
have shown clearly, increased incidence of SDB in patients
with PCOS. In this review, we shall explore the inter-relationship
between the pathophysiology of PCOS and SDB.
[Back to top]
Depression in Sleep Related Breathing Disorder
Shyam Subramanian, Mary Rose and Salim Surani
Sleep deprivation and sleep disruption have long been associated
with mood disorders, both as a cause as well as an effect.
Sleep-disordered breathing results in significant and persistent
sleep disruption, which in turn leads to significant neurocognitive
deficits [1,2] and major depression [3-6]. Various pathophysiologic
mechanisms may play a role in modulating mood changes in these
patients. Treatment for sleep-disordered breathing often improves
mood [4, 7], though the data may suggest a placebo response
[8]. Patients with sleep-disordered breathing should be carefully
screened for mood disorders, and patients with major depression
should be screened for possible underlying sleep-disordered
breathing.
[Back to top]
Sleep Related Disorders in the Elderly: An Overview
Salim Surani and Alamgir Khan
Adequate sleep is important for health and quality of life
at all ages. Refreshing sleep requires both quality and quantity,
so much so that an inadequacy of either leads to overall higher
mortality rates. Numerous studies have sited significant changes
in sleep that typically occur with aging and primary sleep
disorders are more common in the elderly than in younger patients.
As many as half of persons over 65 have some complaint relating
to sleep. There is a high prevalence of insomnia in the elderly
population and elderly patients also frequently suffer from
sleep-disordered breathing, restless legs syndrome, periodic
leg movement disorder, circadian rhythm disturbances, narcolepsy,
and rapid eye movement behavior disorder. Unfortunately, sleep
problems in the elderly are often mistakenly considered a
normal part of aging. The aim of this article is to review
normal sleep, sleep and the major causes of sleep disturbances
in the elderly. Attention has been given to diagnosis and
appropriate interventions, since sleep disturbances left untreated
can have significant negative impact in terms of life expectancy,
general health outcome and quality of life.
[Back to top]
Association of Sleep Apnea Syndrome and Diabetes Mellitus
Salim Surani and Joseph Varon
Several studies have shown a correlation between obstructive
sleep apnea (OSA) and obesity, as well as obesity and diabetes
mellitus. This is probably related to the fact that patients
with OSA are likely to have a high prevalence of the risk
factors that comprise metabolic syndrome. It has been shown
that sleep deprivation when induced experimentally can cause
glucose intolerance and many studies have established the
association between sleep apnea and type two diabetes mellitus.
There is also a proven association between snoring and sleep
apnea as well as snoring and metabolic syndrome. In the current
article we review the patho-physiology of hyperglycemia, insulin
resistance due to sleep apnea, and treatment of OSA with continuous
positive airway pressure therapy. Continuous positive airway
pressure (CPAP) does, in fact, lead to improvement in insulin
resistance and lowered hemoglobin A1C levels. The question
that remains to be answered is whether the association between
sleep apnea and the components of metabolic syndrome is one
of co-existence or causality, but it can no longer be denied
that there is a strong relationship which should lead to investigation
of one if the other is found.
[Back to top]
Airway Remodeling: Effect of Current and Future Asthma
Therapies
Janette K. Burgess and Lyn M. Moir
Airway remodeling (the structural changes which occur in the
airways) is one of the characteristic features of severe persistent
asthma. These changes include thickening of the laminar reticularis,
an increase in the bulk of the airway smooth muscle, thickening
of the basement membrane and alterations in the profile of
extracellular matrix proteins in the airway wall. The mechanisms
leading to airway remodeling are not well understood. Current
asthma therapies are effective at reducing airway inflammation
and hyperresponsiveness but their effect on airway remodeling
is not as evident. Inhaled glucocorticoids have been reported
to reduce the thickness of the basement membrane but also
to be ineffective at combating remodeling. Similarly, leukotriene
receptor antagonists have been shown to prevent or reverse
matrix protein deposition in some models of asthma but to
be without effect or increase extracellular matrix protein
deposition from airway smooth muscle cells. Less is known
about the effects of β2-agonists
on airway remodeling.
Another class of drugs that is currently being trialed as
asthma therapeutics are the phosphodiesterase 4 inhibitors.
Recent studies have indicated that this class of drugs may
have a role to play in the prevention or reversal of airway
remodeling.
This review aims to discuss what is currently known about
the effectiveness of current therapies for the management
of airway remodeling in asthma and to summarize the recent
advances that may represent valuable additions for the reversal
or prevention of airway remodeling in asthma.
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Neurologic Sequelae in Critical Illness: Evaluation
and Outcomes
Mary R. Suchyta and Ramona O. Hopkins
Critical illness is associated with multiple system organ
dysfunction, and neurologic dysfunction is increasingly assessed
and recognized. Neurologic dysfunction includes encephalopathy,
cognitive, neuromuscular and psychiatric impairments, all
of which can be severe and are associated with significant
morbidity. Medical technological advances have improved central
nervous system monitoring in critically ill patients, allowing
quick and reliable diagnosis neurologic dysfunction such as
delirium, sensory processing deficits, seizures, and encephalopathy
to name a few. A number of neurologic evaluation tools are
available to assess the neurologic status of critically ill
patients both acutely, as well as long-term. Each tool provides
unique information regarding neurologic status and has associated
strengths and weakness. Identification of neurologic dysfunction
allows for the development of working plans for prognostication,
therapeutics, and rehabilitation that address the needs of
each ICU survivor. This review focuses on the evaluation of
neurologic sequelae during critical illness and long-term
neurologic outcomes in survivors of critical illness.
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