Dreaming is a common, enduring, and fascinating part of the anesthetic experience, but its cause and timing remain elusive. Patients typically report that they were dreaming during anesthesia, but the actual timing of anesthetic dreaming is unknown. The following evidence supports the hypothesis that dreaming occurs intraoperatively and is related to light or inadequate anesthesia: (1) The incidence of dreaming has decreased as anesthetic techniques have improved; (2) dreamers exhibit more clinical signs of light anesthesia or report more awareness than non dreamers; (3) dreamers may receive lower doses of anesthetic drugs than non dreamers and emerge more rapidly from anesthesia; (4) the content of dreams may involve surgical topics or events occurring during anesthesia; and (5) in one study, the incidence of dreaming was lower in Bispectral Index (BIS)-monitored patients. Alternatively, dreaming may occur during emergence from anesthesia, when the brain is still affected by sedative concentrations of anesthetic drugs and the patient enters a sleep state. Few studies have assessed the relation between dreaming and depth of anesthesia, and their results were inconclusive.Most recently, in the B-Aware Trial, no differences in depth of anesthesia, as measured by BIS, were detected between dreamers and non dreamers. However, the patients were at high risk of awareness, and BIS data were collected manually and were only recorded in the BIS group and during maintenance. No studies investigating the relation between dreaming and depth of anesthesia during recovery were identified. Why is the investigation of dreaming during anesthesia important? Dreaming is one of the most common side effects of anesthesia but remains puzzling and requires explanation. Dreaming is sometimes distressing to patients and may decrease satisfaction with care. Some patients who report dreaming fear that their anesthetic was inadequate and that their experience was, in fact, awareness. Indeed, in a minority of cases, dreaming may truly represent near-miss awareness. The investigators therefore tested the hypothesis that dreaming during anesthesia is associated with light or inadequate anesthesia, as evidenced by higher median BIS values during maintenance of anesthesia. The investigators also explored the depth of anesthesia until emergence, the form and content of dreams, the predictors of dreaming during anesthesia, and the effect of dreaming on quality of recovery and satisfaction with anesthetic care
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
100
The anesthesiologist adjusted the intravenous speed of remifentanil and propofol to maintain the bispectral index (BIS, BIS monitor; Aspect Medical System, Newton, MA) between 40-50 and 50-60 during the operation.
The anesthesiologist adjusted the intravenous speed of remifentanil and propofol to maintain the bispectral index (BIS, BIS monitor; Aspect Medical System, Newton, MA) between 40-50 and 50-60 during the operation.
Shengjing Hospital
Shenyang, Liaoning, China
RECRUITINGMean blood pressure
record mean blood pressure during the surgery. Systolic, diastolic, or both pressures don't need to be assessed during the study period.
Time frame: 5 minutes after entering the operation room
Mean blood pressure
record mean blood pressure during the surgery. Systolic, diastolic, or both pressures don't need to be assessed during the study period.
Time frame: procedure (anesthesia induction)
Mean blood pressure
record mean blood pressure during the surgery. Systolic, diastolic, or both pressures don't need to be assessed during the study period.
Time frame: at the end of surgery
Mean blood pressure
record mean blood pressure during the surgery. Systolic, diastolic, or both pressures don't need to be assessed during the study period.
Time frame: procedure (anesthesia extubation)
Mean blood pressure
record mean blood pressure during the surgery. Systolic, diastolic, or both pressures don't need to be assessed during the study period.
Time frame: the time when leaving the operation room
heart rate
record heart rate during the surgery
Time frame: 5 minutes after entering the operation room
heart rate
record heart rate during the surgery
Time frame: procedure (Anesthesia induction)
heart rate
record heart rate during the surgery
Time frame: at the end of surgery
heart rate
record heart rate during the surgery
Time frame: procedure (anesthesia extubation)
heart rate
record heart rate during the surgery
Time frame: the time when leaving the operation room
Bispectral Index (BIS)
record BIS during the surgery. The range was 0-100. We control the range of BIS in 40-60 during the surgery
Time frame: 5 minutes after entering the operation room
Bispectral Index (BIS)
record BIS during the surgery. record BIS during the surgery. The range was 0-100. We control the range of BIS in 40-60 during the surgery
Time frame: procedure (Anesthesia induction)
Bispectral Index (BIS)
record BIS during the surgery. record BIS during the surgery. The range was 0-100. We control the range of BIS in 40-60 during the surgery
Time frame: at the end of surgery
Bispectral Index (BIS)
record BIS during the surgery. record BIS during the surgery. The range was 0-100. We control the range of BIS in 40-60 during the surgery
Time frame: procedure (anesthesia extubation)
Bispectral Index (BIS)
record BIS during the surgery. record BIS during the surgery. The range was 0-100. We control the range of BIS in 40-60 during the surgery
Time frame: the time when leaving the operation room
Total dose of propofol
record total dose of propofol
Time frame: at the end of surgery
Dream
Dreaming during anesthesia was defined as any experience that was described by the patient as dreaming and was thought by the patient to have occurred between the induction of anesthesia and the first moment of consciousness after anesthesia.27 Awareness was defined as postoperative recall of intraoperative events. All patients who reported dreaming were considered to be "dreamers" for the purpose of the analyses, whether or not they could remember the narrative of the dream. However, only dreaming reports where the narrative was remembered were classified using five-point Likert scales as follows Emotional content (1 very negative; 5 very positive) ● Memorability (1 can't remember narrative of dream; 5 most memorable ever) ● Visual vividness (1 not at all vivid; 5 most vivid ever) ● Amount of sound (1 no sound; 5 most sound ever)
Time frame: at the end of surgery
Postoperative adverse effects
record postoperative adverse effects
Time frame: 24 hours after surgery
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