Page 213 - Cardiac Nursing

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C HAPTER 8 / Sleep 189
Fear of death, reinfarction, or inability to resume former living held in whispered voices, and reduced rounds and procedures
patterns are common as described more fully in Chapter 33. It is were implemented. The changes yielded increased patient and
not surprising that anxiety and depression, typically accompanied staff satisfaction, actual sleep for patients, and improved outcomes
by poor sleep, are common after MI; many patients report trou- related to length of stay, nosocomial infections, and ventilator
blesome insomnia that lasts for months and sometimes years. This days. 217
may in fact be due to altered sleep architecture after acute MI due
to the infarction itself and its associated physiological and inflam- Sleep After Cardiac Surgery
matory changes. 210
Sleep apnea may increase the risk of CHD via pathways medi- Sleep disruption after surgery is related to the magnitude of pro-
ated by hypertension and the metabolic consequences of increased cedure and associated postoperative care, asynchrony between pa-
oxidative stress, C-reactive protein, and insulin resistance. PSG- tient needs and unit procedures, and temporary physiological
verified sleep disruptions and desaturations are associated with ad- changes in brain stem and hypothalamus due to circulatory
verse changes in coagulation proteins/factors and increased pro- changes. Patients who undergo cardiac surgery experience dra-
thrombotic state. 211 Patients with OSA may also be obese and matic sleep pattern disturbances (SPD). Severe sleep deprivation
have a greater prevalence of other underlying cardiovascular risk is common in the early postoperative period, with only a few
factors suggesting a bidirectional relationship. Poor sleep appears hours of fragmented sleep each 24 hours and virtual absence of
to be a precursor to MI as symptoms of insomnia, habitual short slow-wave and REM sleep. 218 One small study comparing preop-
sleep, waking up exhausted, daytime sleepiness, and frequent nap- erative and postoperative PSG recordings in six men who under-
ping are common in the preceding months. One study of prodro- went CABG surgery revealed a significant decrease in mean sleep
mal acute MI symptoms found that sleep disturbance as early as time, mean percentage stages 3 to 4 sleep, and mean REM sleep
1 month prior to an acute MI was reported by as many as 47% of with reduced sleep time correlated with behavioral and mental
women participating in the study. 212 A common link with the pe- changes. 219 Additionally, patient ventilator discordance causes
riod of depression and elevated inflammatory markers that often sleep disruption. Proportional assist ventilation (a mode of partial
precedes MI is a possible explanation for these symptoms. 213 An ventilatory support in which the ventilator applies pressure in
OSA has also been linked to subclinical CHD as measured by proportion to the inspiratory effort) may be more efficacious than
coronary artery calcification, and attention to OSA as a modifi- pressure support ventilation in matching ventilatory requirements
able cardiac risk factor is becoming increasingly important. 214 with ventilator assistance; therefore, resulting in fewer patient–
ventilator asynchronies and better quality of sleep. 220 Another fac-
Sleep in the Coronary Care Unit (CCU) tor is the type of circulatory assist used during the surgery. Off-
pump CABG surgical procedures have been advocated to reduce
Specialized CCUs reduce inhospital deaths after MI, but they can the adverse effects of cardiopulmonary bypass on the brain. An
be far from optimal environments for sleep. The setting is unfa- analysis using both objective and subjective measures of sleep and
miliar and frightening to patients, the schedule and bedtime rou- mood disturbance between patients after on-pump and off-pump
tines differ from those at home, noise and lighting may never be suggests that off-pump surgery was associated with better objec-
completely suppressed, and interruptions for patient care proce- tive sleep continuity (decreased percentage of wake time after
dures are frequent. Sedatives and analgesics are routinely used in sleep onset and fewer awakenings) but not longer sleep duration
cardiovascular patients, yet they have the potential for side effects, after controlling for age and sex. 221 The patients did not differ
such as delirium and sleep architecture disruption. These medica- overall in subjective sleep characteristics, mood disturbance, or
tions are extremely important in providing patient comfort; how- preoperative sleep quality. The authors concluded that off-pump
ever, the goals of care must focus on the right balance of sedative coronary artery bypass surgery may improve sleep continuity dur-
and analgesic administration while reducing unnecessary or ing the early postoperative period. 221
overzealous use. True sleep versus the appearance of sleep due to As with the coronary care environment, cardiac surgical pa-
sedating side effects of medications is important to assess in the tients report sleep disturbances and distress at uninterrupted sleep
CCU. because of nursing care. Contributing environmental and clinical
In PSG studies, CCU patients typically have a pattern of light, factors to postoperative sleep problems include persistent inter-
fragmented sleep with reduced slow-wave and REM sleep, fre- ruptions and activity, high noise and lighting levels, anxiety, pain,
quent stage changes, and considerable night-time wakefulness. 215 and medications. 216 Additionally, cardiac surgery patients may be
Although total sleep time is not necessarily reduced, the normal elderly and have pre-existing sleep disorders. Sleep deprivation of-
circadian sleep–wake rhythm is disrupted, with sleep occurring off ten is implicated as a risk factor for the postoperative delirium that
and on during the 24 hours. REM and slow-wave (deep) sleep develops in some cardiac surgical patients.
may be significantly decreased and disrupted. Sleep is more dis- Although sleep patterns gradually improve after cardiac sur-
turbed as illness severity increases. Sleep patterns may improve gery, slow-wave and REM sleep may be suppressed for several
over time with improving health status, fewer interruptions for weeks after the patient returns home, with many patients report-
care, and increased adaptation to the CCU environment. Al- ing continuing sleep disturbances. The cause of sleeplessness after
though logic and earlier studies suggested that increased noise in CABG surgery may be temporary deterioration of circulation in
the ICU may be a major contributor to poor sleep, later studies the centers of the brain stem and hypothalamus that control sleep
suggested that patient monitoring and pain may play a larger and awakening. Improvement of the circulation in these centers
role. 216 Ruggiero and Dziedzic 217 demonstrated that environ- occurs a few months after the operation helps to regain sleep con-
mental disruptions are not inevitable by implementing a daily, trol and reduce sleep disturbances over time. 222 An initial con-
2-hour, quiet time in intensive care units. Patients were offered tributing factor for some patients with heart valve replacements is
earplugs, do not disturb signs were posted, conversations were noise generated by the mechanical valve prosthesis, including