Memory in relation to depth of sedation in adult mechanically ventilated intensive care patients.
OBJECTIVE
To investigate the relationship between memory and intensive care sedation.


METHODS
Prospective cohort study over 18[Symbol: see text]months in two general intensive care units (ICUs) in district university hospitals.


METHODS
313 intubated mechanically ventilated adults admitted for more than 24 h, 250 of whom completed the study.


METHODS
Patients (n=250) were interviewed in the ward 5 days after discharge from the ICU using the ICU Memory Tool. Patient characteristics, doses of sedative and analgesic agents, and sedation scores as measured by the Motor Activity Assessment Scale (MAAS) were collected from hospital records after the interview.


RESULTS
Patients with no recall (18%) were significantly older, had higher baseline severity of illness, and experienced fewer periods of wakefulness (median proportion of MAAS score 3; 0.37 vs. 0.70) than those who had memories of the ICU (82%). Multivariate analyses showed that increasing proportion of MAAS 0-2 and older age were significantly associated with having no recall. Patients with delusional memories (34%) had significantly longer ICU stay (median 6.6 vs. 2.2 days), higher baseline severity of illness, higher proportions of MAAS scores 4-6, and more administration of midazolam than those with recall of the ICU without delusional memories.


CONCLUSIONS
Heavy sedation increases the risk of having no recall, and longer ICU stay increases the risk of delusional memories. The depth of sedation during total ICU stay as recorded with the MAAS may predict the probability of having memories of the ICU.
Samuelson
Karin
K
Division of Nursing, Lund University, Department of Health Sciences, Box 157, 22100, Lund, Sweden. karin.samuelson@med.lu.se
Lundberg
Dag
D
Fridlund
Bengt
B
D000368:Aged; D015331:Cohort Studies; D016292:Procedural Sedation / Q000379:methods*; D005260:Female; D006785:Hospitals, University; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D007362:Intensive Care Units; D007407:Interviews as Topic; D008297:Male; D008568:Memory / Q000187:drug effects*; D008875:Middle Aged; D011446:Prospective Studies; D012121:Respiration, Artificial; D013548:Sweden
D006993:Hypnotics and Sedatives