Sleep during mechanical ventilation

Updated Perspectives on the Management of Sleep Disorders in the Intensive Care Unit

Sleep disorders and circadian dysrhythmias are extremely prevalent in critically ill patients. Impaired sleep has a variety of etiologies, exhibits a wide range of negative effects and, moreover, might deteriorate the patient's prognosis. Despite a number of scientific findings and increased awareness, the importance of sleep optimization is still lower on the list of priories in the intensive care unit (ICU). The techniques of measuring and the evaluation of sleep quantity and quality are a great challenge in the ICU setting. The subjective and objective tools of sleep validation continue to suffer from deficiencies. Treatment approaches to improve the critically ill patient's sleep have focused on non-pharmacologic and pharmacologic strategies with some promising results. But pharmacological interventions alone could not provide sufficient patient benefit. Being aware and knowing of sleep problems and the beneficial effect of the necessary therapies in ICU patients requires greater acceptance. The application of available methods and the development of new methods to prevent sleep disorders in the ICU offer the potential to improve the critically ill patient's outcome.

Sleep of critically ill children in the pediatric intensive care unit: a systematic review

Critically ill children in the pediatric intensive care unit (PICU) are exposed to multiple physical, environmental and pharmacologic factors which increase the propensity for sleep disruption and loss and may, in turn, play a role in short-term recovery from critical illness and long-term neurocognitive outcomes. Mechanically ventilated children receive sedative and analgesic medications, often at high doses and for long durations, to improve comfort and synchrony with mechanical ventilation. Sedatives and analgesics can decrease slow wave sleep and rapid eye movement sleep. Paradoxically, sedative medication doses are often increased in critically ill children to improve the subjective assessment of sedation and sleep, leading to further agitation and deterioration of sleep quality. The heterogeneity in age and critical illness encountered in the PICU pose several challenges to research on sleep in this setting. The present article reviews the available evidence on sleep in critically ill children admitted to the PICU, with an emphasis on subjective and objective methods of sleep assessment used and special populations studied, including mechanically ventilated children and children with severe burns.

Sleep disturbances in patients admitted to a step-down unit after ICU discharge: the role of mechanical ventilation

BACKGROUND

Severe sleep disruption is a well-documented problem in mechanically ventilated, critically ill patients during their time in the intensive care unit (ICU), but little attention has been paid to the period when these patients become clinically stable and are transferred to a step-down unit (SDU). We monitored the 24-h sleep pattern in 2 groups of patients, one on mechanical ventilation and the other breathing spontaneously, admitted to our SDU to assess the presence of sleep abnormalities and their association with mechanical ventilation.

METHODS

Twenty-two patients admitted to an SDU underwent 24-h polysomnography with monitoring of noise and light.

RESULTS

One patient did not complete the study. At night, 10 patients showed reduced sleep efficiency, 6 had reduced percentage of REM sleep, and 3 had reduced percentage of slow wave sleep (SWS). Sleep amount and quality did not differ between patients breathing spontaneously and those on mechanical ventilation. Clinical severity (SAPS(II) score) was significantly correlated with daytime total sleep time and efficiency (r = 0.51 and 0.5, P < 0.05, respectively); higher pH was correlated with reduced sleep quantity and quality; and higher PaO(2) was correlated with increased SWS (r = 0.49; P = 0.02).

CONCLUSIONS

Patients admitted to an SDU after discharge from an ICU still have a wide range of sleep abnormalities. These abnormalities are mainly associated with a high severity score and alkalosis. Mechanical ventilation does not appear to be a primary cause of sleep impairment.

Adverse effects of sleep deprivation in the ICU

The hospital is not conducive to sleep. Patients in the ICU are particularly susceptible to sleep disruption secondary to environmental and medical issues. Despite the frequency of sleep disruption in the ICU, the quality of critically ill patients' sleep is often overlooked. This article discusses the following issues essential to understanding the factors associated with sleep loss in the ICU: (1) core elements to consider from the baseline sleep history, (2) impact of the ICU environment on the ICU patient's sleep pattern, and (3) overall systematic impact of sleep deprivation on the ICU patient.

Patient-ventilator interaction and sleep in mechanically ventilated patients: Pressure support versus proportional assist ventilation*

OBJECTIVES

To understand the role of patient-ventilator asynchrony in the etiology of sleep disruption and determine whether optimizing patient-ventilator interactions by using proportional assist ventilation improves sleep.

DESIGN

Randomized crossover clinical trial.

SETTING

A tertiary university medical-surgical intensive care unit.

PATIENTS

Thirteen patients during weaning from mechanical ventilation.

INTERVENTIONS

Patients were randomized to receive pressure support ventilation or proportional assist ventilation on the first night and then crossed over to the alternative mode for the second night. Polysomnography and measurement of light, noise, esophageal pressure, airway pressure, and flow were performed from 10 pm to 8 am. Ventilator settings (pressure level during pressure support ventilation and resistive and elastic proportionality factors during proportional assist ventilation) were set to obtain a 50% reduction of the inspiratory work (pressure time product per minute) performed during a spontaneous breathing trial.

MEASUREMENTS AND MAIN RESULTS

Arousals per hour of sleep time during pressure support ventilation were 16 (range 2-74) and 9 (range 1-41) during proportional assist ventilation (p = .02). Overall sleep quality was significantly improved on proportional assist ventilation (p < .05) due to the combined effect of fewer arousals per hour, fewer awakenings per hour (3.5 [0-24] vs. 5.5 [1-24]), and greater rapid eye movement (9% [0-31] vs. 4% [0-23]), and slow wave (3% [0-16] vs. 1% [0-10]) sleep. Tidal volume and minute ventilation were lower on proportional assist ventilation, allowing for a greater increase in Paco2 during the night. Patient-ventilator asynchronies per hour were lower with proportional assist ventilation than with pressure support ventilation (24 +/- 15 vs. 53 +/- 59; p = .02) and correlated with the number of arousals per hour (R = .65, p = .0001).

CONCLUSIONS

Patient ventilator discordance causes sleep disruption. Proportional assist ventilation seems more efficacious than pressure support ventilation in matching ventilatory requirements with ventilator assistance, therefore resulting in fewer patient-ventilator asynchronies and better quality of sleep.

Sleep in acute care units

Patients in the acute care units (ACU) are usually critically ill, making them more susceptible to the unfavorable atmosphere in the hospital. One of these unfavorable factors is sleep disruption and deprivation. Many factors may affect sleep in the ACU, including therapeutic interventions, diagnostic procedures, medications, the underlying disease process, and noise generated in the ACU environment. Many detrimental physiological effects can occur secondary to noise and sleep deprivation, including cardiovascular stimulation, increased gastric secretion, pituitary and adrenal stimulation, suppression of the immune system and wound healing, and possible contribution to delirium. Over the past few years, many studies have endeavored to objectively assess sleep in the ACUs, as well as the effect of mechanical ventilation and circadian rhythm changes critically ill patients. At this time, therefore, it is important to review published data regarding sleep in ACUs, in order to improve the knowledge and recognition of this problem by health care professionals. We have therefore reviewed the methods used to assess sleep in ACUs, factors that may affect sleep in the ACU environment, and the clinical implications of sleep disruption in the ACU.