Benno Bonke

The influence of psychological variables on postoperative anxiety and physical complaints in patients undergoing lumbar surgery

Abstract Previous research has indicated that postoperative distress is influenced by diverse biographic, medical and psychological variables, such as personality, coping behaviours and anxiety. The influence of state variables, apart from anxiety and coping behaviour, has received scant attention. Furthermore, the influence of coping behaviour has remained unclear. The present study investigated coping behaviour and indications of physical distress, i.e., preoperative fatigue, leg pain and back pain, besides preoperative anxiety, as predictors of postoperative anxiety and physical complaints in 126 patients undergoing lumbar surgery. Preoperative anxiety and leg pain independently predicted more postoperative anxiety beyond the influence of age, sex and medical variables. Preoperative anxiety and fatigue independently predicted more postoperative physical complaints. No associations were found between the coping behaviours and the postoperative variables. The implications of these results are discussed in relation to intervention strategies aimed at diminishing the stress of surgery.

Implicit memory for words presented during anaesthesia

Abstract Tests for implicit memory seem to be rather insensitive to the amount of attention given to stimuli during study. In the experiment reported here, the effect of a complete absence of attention during presentation of stimulus material on implicit memory performance was studied. Surgical patients were auditorily presented with exemplars of word categories during general anaesthesia. At the earliest convenient time after surgery, they were requested to generate category exemplars. Although none of the patients expressed any conscious recollection of events during the surgical episode, experimental patients generated significantly more critical exemplars than a control group. Apparently, information presented during anaesthesia can influence post-operative performance in an implicit memory task. Repetition priming seems possible even in the absence of attentional processing at the time of encoding. It is argued that the nature of the unattended encoding process can best be described as the automatic ...

Memory function during propofol and alfentanil anesthesia: predictive value of individual differences.

Background Conscious recall and implicit memory have been shown to depend on hypnotic state as measured by electroencephalographic (EEG) bispectral index (BIS). A third expression of memory (unconscious–controlled memory) was recently observed after moderate to light sedation (BIS, 70–80). The present study investigated memory function during deep sedation (BIS, 60–70). As memory effects are small, the authors studied potential predictors of individual differences in memory performance. Methods Memory function and speed of information processing were assessed in 56 outpatients before surgery. During propofol anesthesia supplemented with alfentanil, patients heard a series of words while anesthesia was titrated to BIS, 60–70. In between words, response to command was assessed using the Isolated Forearm Technique. The authors tested memory with a word stem completion task and process dissociation procedure to distinguish explicit from implicit effects. Results Mean (± SD) BIS during word presentation was 64.0 ± 3. Patients with conscious recall of verbal commands (n = 9) did not recall or recognize presented words. Even so, the process dissociation procedure revealed evidence of memory by a significantly higher hit rate in the inclusion condition (0.26) than in the exclusion condition (0.12). Patients without conscious recall showed no evidence of memory for presented words. Hit scores correlated significantly with scores in the preoperative memory test (r = 0.35). Conclusions The authors found evidence of weak explicit memory function during anesthesia titrated to BIS, 60–70. The observations strongly suggest that postoperative memory relates to awareness during anesthesia, but the nature of this relation remains unclear. Memory seems more likely in patients with good preoperative memory performance.

Auditory information processing during adequate propofol anesthesia monitored by electroencephalogram bispectral index

Memory for intraoperative events may arise from inadequate anesthesia when the hypnotic state is not continuously monitored. Electroencephalogram bispectral index (BIS) enables monitoring of the hypnotic state and titration of anesthesia to an adequate level (BIS 40 to 60). At this level, preserved memory function has been observed in trauma patients. We investigated memory formation in elective surgical outpatients during target-controlled propofol anesthesia supplemented with alfentanil. While BIS remained between 40 and 60, patients listened to a tape with either familiar instances (exemplars) from two categories (Experimental [E] group, n = 41) or bird sounds (Control [C] group, n = 41). After recovery, memory was tested directly and indirectly. BIS during audio presentation was on average (± sd) 44 ± 5 and 46 ± 5 for Groups E and C, respectively. No patient consciously recalled the intraoperative period, nor were presented words recognized reliably (Group E, 0.9 ± 0.8 hits; Group C, 0.8 ± 0.8 hits) (P = 0.7). When asked to generate category exemplars, Group E named 2.10 ± 1.0 hits versus 1.98 ± 1.0 in Group C (P = 0.9). We found no explicit or implicit memory effect of familiar words presented during adequate propofol anesthesia at BIS levels between 40 and 60 in elective surgical patients.

Unconscious learning during anaesthesia

Forty‐three surgical patients were, during general anaesthesia, presented (via headphones) with either statements about common facts of some years ago (group A), or new verbal associations, i.e. the names of fictitious, nonfamous people (group B). None had any recall of intra‐operative events. In a postoperative test of indirect memory, patients in group A answered more questions about the ‘common facts’ correctly than those in group B (p < 0.005), which reflects the activation of pre‐existing knowledge. Furthermore, patients in group B designated more ‘nonfamous names’ as famous (thus falsely attributing fame) than patients in group A (p < 0.001), which demonstrates that information‐processing during anaesthesia can also take place as unconscious learning.

Implicit memory tested in children during inhalation anaesthesia

Memory for stimuli presented during inhalation anaesthesia was tested in 80 children undergoing eye surgery. Two groups were exposed, in a random double‐blind study, to repeated neutral phrases including either the colour orange or green. A postoperative colouring task was used as a test of implicit memory to detect any preference for the colour named under anaesthesia. No colour preference attributable to implicit memory could be demonstrated. One patient had a distinct preference for the named colour. No patient remembered any intra‐operative events.

Information processing during general anesthesia: Evidence for unconscious memory

Memory for words presented during general anesthesia was studied in two experiments. In Experiment 1, surgical patients (n=80) undergoing elective procedures under general anesthesia were presented shortly before and during surgery with words via headphones. At the earliest convenient time after surgery (within 5 h) and 24 h later, memory was tested by asking patients to complete auditorily presented word stems with the first word that came to mind and to leave out words they remembered having heard earlier (exclusion task). Moreover, patients were requested to perform a “yes/no” forcedchoice recognition task to assess recognition memory for both the pre- and intraoperative words. Memory for the material presented during anesthesia was demonstrated immediately after surgery and 24 h later by means of both tasks. In a second similar experiment (n=80), the results were replicated. These findings show that anesthetized patients can process information that was presented intraoperatively.

Memory during general anesthesia: Practical and methodological aspects

Evidence coming from several studies into memory and awareness during general anesthesia suggests that in surgical patients who seem to be adequately anesthetized (i.e., unaware of what happens in the operating theater), some form of cognitive functioning is preserved. This finding has important implications both for clinical practice and for memory research. In order to give the methodological background of the present situation in this field of research, this article deals, on the basis of recent experiments, with important methodological aspects of studies into perception and memory during general anesthesia.

Implicit memory during balanced anaesthesia. Lack of evidence.

The effect of the number of presentations on implicit memory for words was studied in anaesthetised patients. During standardised, balanced anaesthesia, 81 surgical patients were presented with less common specimens of familiar word categories. For each of three word categories the number of word presentations varied between the patients (0 (control), 5, or 30 presentations). Postoperatively, repetition priming was tested by asking patients to generate exemplars for each of the word categories. No implicit memory for the words presented during anaesthesia was found and consequently no effect of number of word presentations could be demonstrated. It is suggested that this finding, which contradicts previous results, may be caused by the relatively low familiarity of the words used.

A revaluation of the adaptiveness of avoidant and vigilant coping with surgery

Abstract It has been assumed that an avoidant coping style is less adaptive in patients coping with surgery than a vigilant coping style. Empirical evidence, however, has indicated the contrary. This article, therefore, revaluated the adaptiveness of these coping styles. A review of the literature yielded three conditions of the situation that determine the adaptiveness of coping: controllability of the situation, time-reference and interpretational set. Problem-focused coping, vigilance, active coping and monitoring seem to be more adaptive in controllable situations; emotion-focused coping, avoidance, blunting and passive coping more adaptive when little control is possible. For short-term adaptation, avoidance seems the more adaptive strategy, whereas in the long run vigilance is a better strategy. Regarding interpretational set, avoidance seems more adaptive when patients have to cope with the emotional value of the event; vigilance seems more adaptive when coping with sensory elements of the event. I...