Chest
Volume 129, Issue 6, June 2006, Pages 1468-1477
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Original Research
Sleep in Critically Ill Chemically Paralyzed Patients Requiring Mechanical Ventilation

https://doi.org/10.1378/chest.129.6.1468Get rights and content

Objective

To determine sleep characteristics in patients receiving mechanical ventilation who require a neuromuscular blocking agent (NMBA).

Design

Observational study.

Setting

Adult medical ICU at a university hospital.

Participants

Eighteen patients with respiratory failure requiring mechanical ventilation were classified into three groups based on medication regimen determined a priori: intermittent sedation (IS), continuous sedation (CS), or CS and an NMBA.

Measurements

Twenty-four–hour polysomnography was performed to determine sleep architecture and fragmentation. Measurement of severity of illness, laboratory indexes, patient-care interventions, and drug dosage were compared between groups, and the effects on sleep staging and fragmentation were analyzed. Sleep stages were scored manually using criteria of Rechtschaffen and Kales, as well as by a modified 50-μV voltage criteria for scoring delta activity.

Results

All patients demonstrated abnormal sleep architecture. In each group of patients, the total sleep time (TST) was > 10 h. There was no statistical difference in the delta activity between the two scoring methods; delta activity was increased in all groups: 32.9%, 49.6%, and 43.7% in the IS, CS, and CS/NMBA groups, respectively. Patients receiving NMBAs spent 22% of the sleep period awake. Rapid eye movement sleep could not be detected in the patients receiving NMBAs and was reduced in the other two groups (3.5%). TST, sleep stage, or arousal/awakening index were not statistically correlated with either severity of illness, clinical laboratory indexes, drug dosage, patient-care interventions, or mode of mechanical ventilation.

Conclusion

TST during a 24-h period is not reduced in patients requiring mechanical ventilation. Delta activity is increased and may reflect age, drug, or a contributing metabolic process. The effect of wakefulness in patients receiving chemical paralysis on recovery and weaning from mechanical ventilation, and overall clinical outcome is unknown.

Section snippets

Study Site

The study was performed between June 1, 1999, and December 31, 2000, in the adult medical ICU at the University of California, Davis. The study protocol and consent form were approved by the Institutional Review Board of the Human Subjects Committee. Written informed consent was obtained from the patient or family member if the patient had any altered sensorium or was unable to read or write. All patients were in private rooms that were enclosed on three sides and separated from the nursing

Patient Demographics

A total of 20 patients were enrolled in the study. Eighteen patients underwent final analysis. One patient withdrew from the study after consent was obtained. The recorder malfunctioned during data acquisition in another patient. The study population characteristics are given in Table 1. Overall, ages ranged from 27 to 74 years with a younger population in the CS group (p < 0.02). When the one outlier, a 27-year-old patient, was eliminated from age analysis, no statistical difference existed

Discussion

This is the first study to our knowledge to prospectively compare various groups of critically ill patients requiring mechanical ventilation based on medication regimen. This is one of the largest studies investigating sleep in severely ill patients in the ICU and adds new information in a novel group of patients: those receiving chemical paralysis. As noted in previous studies6, 7 in patients requiring mechanical ventilation, all of our patients displayed abnormal sleep/wake cycles with

ACKNOWLEDGMENT

We thank LeNette Mahan, BSN, and give a special recognition for her participation in establishing the protocol and preparation of each patient for the study and instruction of nursing staff. We extend our thanks to all nursing staff in the medical ICU who participated and cared for the patients, and acknowledge Grant O’Conner, BSN, for his diligence.

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    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml)

    Supported by a grant from the American Lung Association.

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