Age differences in perception and awareness of emotion

We investigated the effects of age and gender on emotional perception and physiology using electrodermal skin conductance response (SCR) and examined whether SCR is related to subjective perceptions of emotional pictures. Older adults found pictures to be more positive and arousing than younger participants. Older women rated pictures more extremely at both ends of the valence continuum: they rated positive pictures more positively and negative pictures more negatively. Elders were less likely to show measurable SCRs. However, magnitude of SCRs when a response occurred did not differ between young and old. Subjective ratings of emotion correlated with physiological responses in younger participants, but they were unrelated in older participants. Thus, in older adults the perception of emotional events was disconnected from the physiological state induced by emotion.

Does anesthetic induction for Cesarean section with a combination of ketamine and thiopentone confer any benefits over thiopentone or ketamine alone? A prospective randomized study

BACKGROUND

The aim of this study was to evaluate the benefit of a combination of thiopentone and ketamine over either of these drugs alone as an induction agent for Cesarean section.

METHODS

Randomized prospective study of 3 groups of 20 patients (Group I: thiopentone alone; Group II: ketamine alone; Group III thiopentone and ketamine combination).

RESULTS

Systolic blood pressure (BP) (as measured at baseline, after induction, at intubation, and at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min): baseline BP did not differ significantly across groups. However, postinduction values were significantly higher for Group II (ketamine alone) (P>0.001), but these values normalized by 30 min postinduction. Diastolic BP (as measured at baseline, after induction, at intubation, and at 5 min, 10 min, 15 min, 20 min, 25 min, 30 min): baseline BP did not differ significantly across groups. After induction, diastolic BP increased significantly in all groups. In Group I and Group III, these values returned to baseline after 10 min, and in Group II at the 30 min postinduction stage. Heart rate (measured at the same time as BP): at rest, presented no significant difference in heart rate across groups. At induction, all groups showed a significant rise in heart rate. At intubation, Group I showed an increase in heart rate, Group II a decrease in heart rate, and Group III no change. These intergroup variations were statistically significant. Apgar scores and umbilical venous gas measurements: although there were intergroup variations, these were not statistically significant. Postoperative pain assessment (subjective) VAS scores: the VAS pain scores 3 h after surgery were significantly higher in Group I, both at rest and coughing, at 24 h after surgery the difference persisted for scores at rest, but equalized during coughing. Postoperative pain assessment (objective) time to first analgesic demand: the duration of time to demand for first analgesic was significantly longer in Group II (ketamine only). Postoperative pain assessment (objective) total consumption of analgesic: patients of Group I consumed a significantly higher amount of analgesics than the other groups. Intraoperative event recall, awareness: no patient reported any adverse events of this nature.

CONCLUSIONS

We conclude that though there were no adverse events and a significantly lower analgesic requirement, the use of ketamine alone as an induction agent in Cesarean section should be avoided, as it causes significant maternal hemodynamic changes. The addition of a reduced dose of ketamine to thiopentone in the induction cocktail confers the benefit of reducing analgesic requirement without side effects. The treatment is safe and effective for the mother and child.

Bolus isoproterenol infusions provide a reliable method for assessing interoceptive awareness

Interoception, defined as the perception of internal body states, plays a central role in classic and contemporary theories of emotion. In particular, deviations from baseline body states have been hypothesized to be integral to the experience of emotion and feeling. Consequently, reliable measurement of interoception is critical to the testing of emotion theories. Heartbeat perception tasks have been considered the standard method for assessing interoceptive awareness, primarily due to their non-invasive nature and technical feasibility. However, these tasks are limited by the fact that above chance group performance rates on heartbeat detection (or the frequency of 'good detectors') are rarely higher than 40%, meaning that such tasks (as they are typically utilized) do not obtain a measure of interoceptive awareness in the majority of individuals. Here we describe a novel protocol for inducing and assessing a range of deviations in body states via bolus infusions of isoproterenol, a non-selective beta adrenergic agonist. Using a randomized, double-blinded, and placebo-controlled experimental design, we found that bolus isoproterenol infusions elicited rapid and transient increases in heart rate and concomitant ratings of heartbeat and breathing sensations, in a dose-dependent manner. Our protocol revealed changes in interoceptive awareness in all 15 participants tested, thus overcoming a major limitation of heartbeat detection tasks. These findings indicate that bolus isoproterenol infusions provide a reliable method for assessing interoceptive awareness, which sets a foundation for further investigation of the role of interoceptive sensations in the experience of emotion.

Reduction of appeasement-related affect as a concomitant of diazepam-induced aggression: evidence for a link between aggression and the expression of self-conscious emotions

Aggressive responding following benzodiazepine ingestion has been recorded in both experimental and client populations, however, the mechanism responsible for this outcome is unclear. The goal of this study was to identify an affective concomitant linked to diazepam-induced aggression that might be responsible for this relationship. Thirty males (15 diazepam and 15 placebo) participated in the Taylor Aggression Paradigm while covertly being videotaped. The videotapes were analyzed using the Facial Action Coding System with the goal of identifying facial expression differences between the two groups. Relative to placebo participants, diazepam participants selected significantly higher shock settings for their opponents, consistent with past findings using this paradigm. Diazepam participants also engaged in significantly fewer appeasement expressions (associated with the self-conscious emotions) during the task, although there were no group differences for other emotion expressions or for movements in general.

[Depth of anaesthesia during intubation: comparison between propofol and thiopentone]

In order to study the depth of anaesthesia during endotracheal intubation, 30 patients received either thiopentone or propofol for anaesthesia induction. The BIS value as a parameter for the depth of anaesthesia and the rate pressure product (RPP) were acquired online. Patients who received thiopentone for anaesthesia induction showed significantly higher BIS values at the moment of intubation and reached BIS values >60 significantly more frequently than patients receiving propofol. The RPP in the propofol group lay significantly below that of the thiopentone patients. For all patients there was an mean increase in BIS values of 8 index points and an increase in the RPP. Therefore, BIS values around 50 should be achieved before intubation in order to avoid the critical BIS value for awareness of >60 despite the increase caused by the intubation procedure. Within 24 h of intubation all patients were interviewed for possible signs of awareness. None of the patients was able to remember the intubation or reported other experiences that indicated an unconscious awareness. Nevertheless, the progress of BIS values in a standardized intubation as performed in the normal clinical routine, shows that the use of thiopentone for initiating anaesthesia results in a very flat level of anaesthesia during intubation. The risk for patients to experience awareness should therefore, not be underestimated. Therefore, when using thiopentone it is recommended to also use a rapid acting muscle relaxant or to select a high ED95 to compensate for the flat level of anaesthesia. Alternatively, repetetive boluses of the hypnotic shortly before intubation should be considered or to revert to propofol. The dosage and pharmacokinetics of the analgesic should also be taken into consideration because an insufficient analgesia leads to a faster flattening of the depth of anaesthesia.

Is BIS monitoring cost-effective?

BIS monitoring is a processed electroencephalogram (EEG) technology that is designed to follow the effects that anesthetics and sedatives have on cerebral function. Much is know about the technology, it's utility and limitations. The economic case for widespread utilization of this technology is weak. There appears to be little opportunity to decrease health care cost by either reduction of drug costs or improved practice efficiency. General use of BIS monitoring to reduce the incidence of intraoperative recall (IR) would cost about USD 10,000 to 25,000 per avoided IR. Total cost to the heath care system would approach one billion US dollars per year, just for use during general anesthetics. More appropriate use of already available drugs and technology would most likely decrease the incidence of IR as effectively, although individual patients who are at high risk for IR may benefit from this technology. However, based on current health care economic standards general use of BIS monitoring does not seem warranted and appears not to be cost-effective.

BIS does not predict dreams reported after anaesthesia

BACKGROUND

In earlier studies, between 1% and 57% of patients have been reported to dream during anaesthesia. Thus, dreaming is much more common than definite memories of real events. We wanted to examine whether dreaming during anaesthesia is related to insufficient hypnotic action, as indicated by BIS levels and, thus, may constitute a risk for awareness.

METHODS

After IRB approval, 2653 consecutive surgical patients were included. BIS registrations were recorded continuously during the anaesthetic procedure. The patients were interviewed on three occasions after anaesthesia. Standard questions, according to Brice, to evaluate awareness and dreaming during anaesthesia were asked. The dreams were categorized as either pleasant/neutral or unpleasant without any further evaluation of the dream content. Episodes with a mean BIS below 40, above 60 and above 70 were identified and subdivided according to duration (1, 2, 4 and 6 min, respectively). The total time as well as number and duration of episodes for the three BIS-levels were used to analyze any relation to reported dreaming. The mean BIS was also analyzed.

RESULTS

Dreaming during anaesthesia was reported by 211 of patients (8.0%) on at least one of the post-operative interviews. BIS data did not show any significant correlation with dreaming, and neither did any of the tested case-specific parameters (gender, age, ASA group, BMI, use of relaxants, induction agent, maintenance agent, length of procedure, omitting N(2)O and concomitant regional anaesthesia).

CONCLUSION

Dreaming during anaesthesia seems to be a separate phenomenon, not in general related to insufficient anaesthesia as indicated by high BIS levels.

Intraoperative dreams reported after general anaesthesia are not early interpretations of delayed awareness

BACKGROUND

Dreams are more frequently reported than awareness after surgery. We define awareness as explicit recall of real intraoperative events during anaesthesia. The importance of intraoperative dreaming is poorly understood. This study was performed to evaluate whether intraoperative dreams can be associated with, or precede, awareness. We also studied whether dreams can be related to case-specific parameters.

METHODS

A cohort of 6991 prospectively included patients given inhalational anaesthesia were interviewed for dreams and awareness at three occasions; before they left the post-anaesthesia care unit, days 1-3 and days 7-14 after the operation. Uni- and multivariate statistical relations between dreams, awareness and case-specific parameters were assessed.

RESULTS

Two hundred and thirty-two of 6991 patients (3.3%) reported a dream. Four of those also reported awareness and remembered real events that were distinguishable from their dream. Awareness was 19 times more common among patients who after surgery reported a dream [1.7% vs. 0.09%; odds ratio (OR) 18.7; P=0.000007], but memories of dreams did not precede memories of awareness in any of the 232 patients reporting a dream. Unpleasant dreams were significantly more common when thiopentone was used compared with propofol (OR 2.22; P=0.005). Neutral or pleasant dreams were related to lower body mass index, female gender and shorter duration of anaesthesia.

CONCLUSIONS

We found a statistically significant association between dreams reported after general anaesthesia and awareness, although intraoperative dreams were not an early interpretation of delayed awareness in any case. A typical dreamer in this study is a lean female having a short procedure.

The effects of depth of isoflurane anesthesia on the performance of mice in a simple spatial learning task

Studies on humans and rodents indicate possible long-term cognitive impairment after surgery or general anesthesia. The goal of this study was to evaluate the effect of various anesthetic concentrations on spatial learning in adult mice. The behavior of adult mice in a T-maze was assessed 28 h after anesthesia (control [0%], low [1%], or high [2%] isoflurane concentration). The mice anesthetized with 1% isoflurane had a significantly poorer performance than did the other 2 groups. The performance of the mice anesthetized with 2% isoflurane was not statistically different from that of the control group. Therefore, low, not high, isoflurane concentration impaired spatial learning in mice.

Prevention of awareness during anaesthesia

Inadequate anaesthesia may lead to awareness. A properly trained anaesthetist, administering anaesthesia according to their knowledge of pharmacology and patient and surgical characteristics, assisted by clinical signs and monitoring, can minimize this risk. Relying upon volatile-based anaesthesia delivered at a concentration of at least 0.5 MAC may be effective, but this precludes the use of total intravenous anaesthesia techniques and in any case may lead to unwanted hypotension. Equipment failure may occur. Benzodiazepines do not protect the patient from awareness. The development of electroencephalographic monitors of anaesthetic depth provides an opportunity to prevent awareness. Two large scale studies, one of which was a randomized trial, have identified a 5-fold reduction in risk of awareness when depth of anaesthesia using bispectral index monitoring was used. The incidence of awareness can be further reduced with currently available techniques used more widely.

Use of the bispectral index to predict a positive awareness reaction to laryngeal mask airway-Fastrach insertion and intubation

AIM

To determine whether the bispectral index (BIS) can be monitored to predict and indicate an awareness reaction to laryngeal mask airway-Fastrach (LMA-Fastrach) insertion and intubation at BIS values between 40 and 60.

METHODS

Fifty-one American Society of Anesthesiologists' (ASA) class I or II status patients aged over 20 years were included in this study. Midazolam 0.1 mg/kg was given for pre-medication, 30 min before induction. For induction, a 0.1-microg/kg bolus injection of remifentanil was followed by infusion, and propofol was administered until the eyelash reflex disappeared; the infusion rate was adjusted to maintain BIS values between 40 and 60. Loss of the eyelash reflex, loss of response to verbal commands, yawning and total propofol consumption were recorded. Patients were tested for awareness twice at 1-min intervals using the isolated forearm technique. The test was considered to be positive if the patient squeezed a hand when asked; after muscle relaxation, the patient was intubated and the test was repeated. In the recovery room and ward, patients were asked whether they could recall this event.

RESULTS

Seven patients tested positive: two following LMA-Fastrach insertion and the remaining five following intubation. None of the patients had recall.

CONCLUSION

Awareness during anaesthesia may occur at BIS levels that indicate adequate anaesthesia, but this is not associated with recall of the events later.

Psychological consequences of awareness and their treatment

Intraoperative awareness with subsequent recall is a rare but serious complication with an incidence of 0.1-0.2%. In approximately one third of the patients who have experienced awareness, late severe psychiatric sequelae may develop. The psychiatric symptoms in these patients fulfil the diagnostic criteria for post traumatic stress disorder. To prevent awareness as a negative outcome after anaesthesia, a thorough perioperative management of anaesthesia is necessary. The definite risk for post traumatic stress disorder following awareness indicates the necessity of postoperative clinical routines to identify awareness patients. The problem must be acknowledged. Professional psychiatric assessment and follow up should constitute standard practice. The treatments of choice are Eye Movement Desensitisation Reprocessing and Cognitive Behaviour Therapy.

The effects of serotonin manipulations on emotional information processing and mood

BACKGROUND

Serotonin is implicated in both mood and cognition. It has recently been shown that antidepressant treatment has immediate effects on emotional information processing, which is much faster than any clinically significant effects. This review aims to investigate whether the effects on emotional information processing are reliable, and whether these effects are related to eventual clinical outcome. Treatment-efficiency may be greatly improved if early changes in emotional information processing are found to predict clinical outcome following antidepressant treatment.

METHODS

Review of studies investigating the short-term effects of serotonin manipulations (including medication) on the processing of emotional information, using PubMed and PsycInfo databases.

RESULTS

Twenty-five studies were identified. Serotonin manipulations were found to affect attentional bias, facial emotion recognition, emotional memory, dysfunctional attitudes and decision making. The sequential link between changes in emotional processing and mood remains to be further investigated.

LIMITATIONS

The number of studies on serotonin manipulations and emotional information processing in currently depressed subjects is small. No studies yet have directly tested the link between emotional information processing and clinical outcome during the course of antidepressant treatment.

CONCLUSIONS

Serotonin function is related to several aspects of emotional information processing, but it is unknown whether these changes predict or have any relationship with clinical outcome. Suggestions for future research are provided.

Use of a target-controlled infusion system for propofol does not improve subjective assessment of anaesthetic depth by inexperienced anaesthesiologists*

BACKGROUND AND OBJECTIVES

Target-controlled infusion, via the calculated effect compartment concentrations, may help anaesthesiologists to titrate anaesthetic depth and to shorten recovery from anaesthesia.

METHODS

In this prospective, randomized clinical study, we compared the performance of six inexperienced anaesthesiologists with <1 yr of training when using target- or manually controlled infusion of propofol, combined with manual dosing of fentanyl. Ninety-two premedicated ASA I-III patients undergoing minor elective urological or gynaecological surgery were assigned to the manual- or target-controlled infusion group. Bispectral index was recorded in a blinded manner. Subjective assessment of anaesthetic depth on a 10 point numerical scale (1 = very deep anaesthesia, 10 = awake) was asked at regular intervals and the correlation with the blinded bispectral index was analysed using the prediction probability, PK. The propofol concentration profile was calculated post hoc.

RESULTS

Propofol administration was similar in both groups with no significant difference for the administered amount and concentrations of propofol. Recovery times were also not different. In both groups, a large percentage of the bispectral index data points recorded during surgery showed bispectral index values below the recommended value of 40, but in the target-controlled infusion group there were significantly less bispectral index values above the recommended upper limit of 60 (2.5% vs. 5.1%).

CONCLUSIONS

A target-controlled infusion system does not help inexperienced anaesthesiologists to assess anaesthetic depth or to shorten recovery times, but may reduce episodes of overly light anaesthesia and thus help to prevent awareness.

Incidence of and risk factors for awareness during anaesthesia

Explicit recall of events during general anaesthesia is detected by direct questioning, as patients may not report awareness spontaneously or if they are questioned non-specifically. More than one interview is needed and credibility of reports should always be verified. The overall incidence of awareness has decreased over the last 40 years and is now 0.1-0.2%. Prospective study of patients who undergo general anaesthesia is the only valid method for determining the incidence of awareness. Studies of patients recruited through referrals by colleagues or advertisements, studies of compensation claims and those carried out through quality improvement systems are inadequate. Several factors increase the risk of awareness, including light anaesthesia, some types of surgery, a history of awareness, chronic use of central nervous system depressants, younger age, obesity, inadequate or misused anaesthesia delivery systems, insufficient knowledge about awareness, and ignoring the use of electroencephalographic monitors when the risk is otherwise increased.

Behavioral and neuroeconomics of drug addiction: competing neural systems and temporal discounting processes

We review behavioral- and neuroeconomic research that identifies temporal discounting as an important component in the development and maintenance of drug addiction. First, we review behavioral economic research that explains and documents the contribution of temporal discounting to addiction. This is followed with recent insights from neuroeconomics that may provide an explanation of why drug-dependent individuals discount the future. Specifically, neuroeconomics has identified two competing neural systems that are related to temporal discounting using brain-imaging techniques that examine the relative activation of different brain regions for temporal discounting. According to the competing neural systems account, choices for delayed outcomes are related to the prefrontal cortex (i.e., the "executive system") and choices for immediate outcomes are related to the limbic brain regions (i.e., the "impulsive system"). Temporal discounting provides a useful framework for future imaging research, and suggests a novel approach to designing effective drug dependence prevention and treatment programs.

Unilateral nondominant electrode placement as a risk factor for recall of awareness under anesthesia during electroconvulsive therapy

BACKGROUND

Awareness under anesthesia can be a frightening experience for patients receiving electroconvulsive therapy (ECT).

CASE REPORT

We present a 19-year-old, 62-kg, bipolar woman who was prescribed right unilateral ECT for a treatment-refractory major depressive episode. Her premedication comprised thiopentone sodium (200 mg) and succinylcholine (30 mg). She received 3 treatments uneventfully. A day after the fourth treatment, she described her awareness of paralysis during the last procedure and refused further treatment despite the marked improvement that had resulted with ECT.

DISCUSSION

Electroconvulsive therapy is more usually administered with bilateral than with unilateral electrode placement. During ECT, awareness under anesthesia and recall of paralysis (resulting from inadequate doses of anesthesia and/or premature administration of the muscle relaxant) may be more common than is generally realized but may not be reported by patients because bilateral ECT tends to obliterate the memory of the ECT procedure. If this is true, unilateral nondominant ECT, which is relatively memory sparing, may increase the chance of recollection of paralysis when narcosis under anesthesia is incomplete. Careful clinical assessment and monitoring of the depth of anesthesia using the bispectral index can minimize this risk of awareness under anesthesia.