Page 211 - Cardiac Nursing

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C HAPTER 8 / Sleep 187
are middle-aged men who are overweight, snore loudly during creases carbon dioxide tension below the apneic threshold; the re-
sleep, and experience daytime sleepiness that interferes with nor- sulting apnea then leads to hypoxemia, which perpetuates the cy-
mal activities; women with sleep apnea are usually post- cle. In addition, cardiac enlargement and pulmonary congestion
menopausal. Other risk factors include a positive family history decrease gas stores in the lungs, which allow wider swings in blood
and race (African Americans, Mexican Americans, Pacific Is- gas values with changes in ventilation. Effective treatment of the
landers, and East Asians). 139–141 Sleep apnea is likely to be wors- HF and low-flow O 2 therapy during sleep help to correct the hy-
ened by sleep deprivation, 142–144 alcohol ingestion, 141,145–147 and poxemia and stabilize the breathing pattern. 166–168 Use of nasal
sedative or hypnotic use. 148 CPAP has also been shown to decrease the severity of central ap-
OSA has significant cardiovascular consequences. 149 Pul- neas in patients with HF. 169,170
monary arterial pressures increase in a stepwise fashion with re-
peated apnea. 150–152 Numerous population-based studies have Snoring and Upper Airway Resistance
also demonstrated a strong association between systemic hyper- Snoring, present in approximately 40% of the population, occurs
tension and sleep apnea. 153–157 Whether the hypertension is because underlying abnormalities cause narrowing of the pharyn-
caused directly by sleep apnea or a related common factor, such as geal airway. Snoring is a primarily inspiratory (but may also be ex-
obesity, is unclear. The Wisconsin Sleep Cohort Study prospec- piratory) noise during sleep caused by partial upper airway ob-
tively evaluated the clinical course of hypertension in patients struction and vibration of the soft tissues. Snoring intensifies as
with OSA and found that blood pressure increased linearly with NREM sleep deepens and diminishes in REM sleep. Factors that
apnea severity. 156,157 The Sleep Heart Health Study, the largest worsen snoring include: obesity, supine position, sleep depriva-
prospective performed to date, found that although some of the tion, use of alcohol or sedatives, and smoking. 171 UARS is a con-
association was related to body mass index, there was a significant dition marked by frequent arousals from sleep related to an in-
relationship between apnea severity and hypertension. 155 crease in respiratory effort needed to overcome resistance to air
Cardiac arrhythmias are relatively common and include pre- flow resulted in disturbed sleep and EDS. 171,172
mature ventricular contractions (PVCs), atrioventricular block, Simple snoring has been associated with a variety of health
and bradycardia. Apneas are often associated with a progressive si- problems including type II diabetes and headaches, but it is possi-
nus bradycardia, sometimes with a prolonged sinus pause, fol- ble that these relationships are coincidental rather than causal. 171
lowed by an abrupt increase in heart rate when breathing resumes. Epidemiologic studies indicate that habitual snoring/UARS is as-
A decrease and subsequent increase in cardiac output parallels the sociated with a greater prevalence depression and insomnia. 173,174
heart rate changes. 158 As association between snoring/UARS and cardiovascular disease
To minimize possible complications, early diagnosis and treat- has also been suggested; 175–178 however, others debate this rela-
ment are critical. The treatment of choice for OSA is nasally ap- tionship. 179 Treatment options for these conditions include CPAP,
plied CPAP. A soft, firmly fitting nasal mask is held in place by posterior pharyngeal airway surgery, or a dental appliance (used to
straps and attached to a bedside blower that provides continuous move the lower jaw and tongue forward, thus increasing the pos-
pressure (usually 5 to 15 cm/H 2 O) to prevent collapse of the up- terior pharyngeal airway space). 171
per airway. Recent improvements in CPAP devices include grad-
ual onset of pressure, separate control of inspiratory and expira- Restless Legs Syndrome (RLS) and
tory pressures, and autotitration of the pressure delivered. 159,160 Periodic Limb Movement (PLMD)
Conservative treatment strategies include weight loss, learning to
sleep in a side-lying position (e.g., putting a ball in a pouch on the RLS is a neurological sensorimotor disorder characterized by dis-
pajama back), and avoidance of alcohol and sedatives. Oral appli- agreeable leg sensations that usually occur prior to sleep onset and
ances which move the lower mandible forward in order to increase accompanied by an almost irresistible urge to move the legs. 10
the posterior airway space are now also available. 161 Pharmaco- Vividly described by the English physician Willis in 1671, 180 the
logical approaches with purported respiratory stimulants (e.g., ac- disorder was more completely characterized in 1945, when Ek-
etazolamide, methylprogesterone, and protriptyline) have had bom described its classic clinical features and made recommenda-
variable effectiveness. 162 Occasionally, surgery is performed to en- tions for treatment. 181 Although, RLS has more recently received
large the upper airway (uvulopalatopharyngoplasty) or to bypass significant attention by the scientific and lay communities, it re-
it (tracheostomy) when other measures do not alleviate the ap- mains poorly understood and under diagnosed.
nea. 163 If the patient has been receiving antihypertensive medica- The four criteria necessary to make the clinical diagnosis of
tion, the dosage may need to be reduced when the sleep apnea is RLS include:
effectively managed.
1. an urge to move the limbs usually associated with paresthesias
or dysesthesias;
Central Sleep Apnea 2. motor restless manifested by using different motor strategies to
Patients with severe congestive heart failure (HF) often have a pat- relieve the discomfort such as floor pacing, tossing and turning
tern of periodic (Cheyne–Stokes) breathing during light sleep in in bed, and rubbing the legs;
which periods of central apnea alternate with hyperpnea. 164,165 3. symptoms that become worse or are exclusively present at rest
This breathing pattern causes recurrent episodes of hypoxemia with at least partial and temporary relief by activity; and
that can further impair the failing heart. Frequent arousals during 4. symptoms that are worse in the evening or night (typically be-
the hyperpneic phase that disrupt sleep can impair daytime alert- tween 6:00 PM and 4:00 AM). 10
ness. 166 One mechanism for the abnormal breathing pattern is
prolonged circulation time that delays the ventilatory responses to Other associated features commonly seen in patients with RLS—
blood gas changes. The resulting hypoxemia sets up a vicious cy- but that are not necessary for the diagnosis—are sleep distur-
cle whereby increased ventilation improves oxygenation but de- bance, daytime fatigue/sleepiness, and involuntary, repetitive,