Combined regional and light general anesthesia: are the risks increased or minimized?

Regional anesthesia during general anesthesia has become increasingly popular in recent years. Most pediatric anesthesiologists are proponents of this practice, and believe that surgical morbidity is reduced, but controversy remains regarding safety. Neuraxial anesthesia during general anesthesia is especially controversial. Unfortunately, outcome studies are lacking but the literature reflects an absence of reported serious morbidity or mortality.

Outcomes after single injection caudal epidural versus continuous infusion epidural via caudal approach for postoperative analgesia in infants and children undergoing patent ductus arteriosus ligation

Adequate postoperative analgesia enhances deep breathing and minimizes respiratory complications after thoracotomy. This study compares postoperative outcomes after single injection caudal epidural vs continuous infusion epidural via caudal approach for postoperative analgesia in infants and children undergoing thoracotomy for patent ductus arteriosus (PDA) ligation. A retrospective chart review was performed for 27 children who had undergone PDA ligation. The children were divided into three groups. We compared patient demographics, surgical duration, anaesthesia duration, length of ICU stay, incidence of emesis requiring treatment, time required to establish regular oral intake, requirement for supplemental intravenous opioids during the first postoperative day, and length of hospital stay. For paediatric patients undergoing PDA ligation, postoperative analgesia with continuous infusion epidural via caudal approach produced shorter ICU stay, less occurrence of postoperative emesis, earlier oral intake, elimination of intravenous opioid supplementation, and shorter hospital stay compared with single injection caudal epidural techniques.

Tempo discrimination of musical patterns: effects due to pitch and rhythmic structure

The purpose of this research was to investigate a set of factors that may influence the perceived rate of an auditory event. In a paired-comparison task, subjects were presented with a set of music-like patterns that differed in their relative number of contour changes and in the magnitude of pitch skips (Experiment 1) as well as in the compatibility of rhythmic accent structure with the arrangement of pitch relations (Experiment 2) Results indicated that, relative to their standard referents, comparison melodies were judged to unfold more slowly when they displayed more changes in pitch direction, greater pitch distances, and an incompatible rhythmic accent structure. These findings are suggested to stem from an imputed velocity hypothesis, in which people overgeneralize certain invariant relations that typically occur between melodic and temporal accent structure within Western music.

The processing of temporal and nontemporal information in the remembering of event durations and musical structure

Within the field of cognitive psychology, one issue of theoretical debate concerns the relationship between an event's temporal (e.g., rhythm, rate, total duration) and nontemporal (e.g., sequence of pitch intervals) information. Some argue these are jointly encoded into the cognitive system, whereas others claim they are encoded in an independent fashion. This issue was investigated in 2 experiments that systematically manipulated participants' attention to the temporal and pitch properties of melodies and then examined participants' subsequent remembering of these structural dimensions. The results indicate that the nature of encoding is strongly dependent on the structure of environmental events and the degree of learning experience. This relationship in turn has implications for theories of both music cognition and time estimation behavior.

The role of learning in remembered duration

In two experiments, the effects of learning on both the accuracy and bias of duration judgments were examined. In Experiment 1, subjects learned one of two tasks (i.e., using a computer software package, building a model car), containing a varying number of action steps, over a one-, three-, or five-trial period. Retrospective judgments of a task's total duration revealed that accuracy was high at intermediate stages of learning but was low at early stages due to an overestimation bias and low at later stages due to an underestimation bias. The number of action steps within a task influenced behavior only at early learning stages where more action steps led to significantly longer duration estimates. Experiment 2 acted as a converging operation in which novice and experienced pianists were asked to estimate, in advance, how long they thought it would take them to play melodies that varied in their degree of familiarity (i.e. recently learned, well learned, extremely well learned). When these estimates were compared with the melodies' actual playing times, results revealed a similar pattern of accuracy and bias as found in Experiment 1. These findings are discussed in terms of a "structural remembering model" that emphasizes the role of event predictability in time estimation behavior.

The processing of temporal and nontemporal information in the remembering of event durations and musical structure

Within the field of cognitive psychology, one issue of theoretical debate concerns the relationship between an event's temporal (e.g., rhythm, rate, total duration) and nontemporal (e.g., sequence of pitch intervals) information. Some argue these are jointly encoded into the cognitive system, whereas others claim they are encoded in an independent fashion. This issue was investigated in 2 experiments that systematically manipulated participants' attention to the temporal and pitch properties of melodies and then examined participants' subsequent remembering of these structural dimensions. The results indicate that the nature of encoding is strongly dependent on the structure of environmental events and the degree of learning experience. This relationship in turn has implications for theories of both music cognition and time estimation behavior.

Task predictability and remembered duration

The effects of structural predictability on remembered duration judgments were examined within the context of the performance of a series of highly familiar tasks. Across a set of three experiments, task predictability was manipulated by the presence or absence of advance expectancies of what tasks were to be performed (Experiment 1), an (in) variant ordering of task performance (Experiment 2), and the placement of interruptions at between- versus within-task locations (Experiment 3). In each case, a higher degree of predictability led to more accurate and reliable duration estimates that were relatively free of bias, while uncertainty decreased accuracy through an overestimation bias. These results not only render insight into the mediational mechanisms responsible for temporal judgments, but also suggest some practical applications for everyday behavior.

Effects of event structure on retrospective duration judgments

Two experiments examined whether varying degrees of event coherence influence the remembering of an event's actual duration. Relying on musical compositions (Experiment 1) or filmed narratives (Experiment 2) as experimental stimuli, the underlying hierarchy of information within events (i.e., melodic intervals or story elements) was either attentionally highlighted or obscured by placing a varying number of accents (i.e., prolonged notes or commercial breaks) at locations that either coincided or conflicted with grammatical phrase boundaries. When subjects were unexpectedly asked to judge the actual duration of events, through a reproduction (Experiment 1) or verbal estimation (Experiment 2) task, duration estimates became more accurate and less variable when the pattern of accentuation increasingly outlined the events' nested relationships. Conversely, when the events' organization was increasingly obscured through accentuation, time judgments not only became less accurate and more variable, but were consistently overestimated. These findings support a theoretical framework emphasizing the effects of event structure on attending and remembering activities.

Harmonic and rhythmic influences on musical expectancy

The effects of harmony and rhythm on expectancy formation were studied in two experiments. In both studies, we generated musical passages consisting of a melodic line accompanied by four harmonic (chord) events. These sequences varied in their harmonic content, the rhythmic periodicity of the three context chords prior to the final chord, and the ending time of the final chord itself. In Experiment 1, listeners provided ratings for how well the final chord in a chord sequence fit their expectations for what was to come next; analyses revealed subtle changes in ratings as a function of both harmonic and rhythmic variation. Experiment 2 extended these results; listeners made a speeded reaction time judgment on whether the final chord of a sequence belonged with its set of context chords. Analysis of the reaction time data suggested that harmonic and rhythmic variation also influenced the speed of musical processing. These results are interpreted with reference to current models of music cognition, and they highlight the need for rhythmical weighting factors within the psychological representation of tonal/pitch information.

Time estimation and expectancies

The purpose of this research was to examine the influence of different types of expectancies on time estimation behavior. In Experiment 1, subjects were led to expect that a given number of trials would occur in a music perception task. In Experiment 2, expectancies concerning the duration of a given waiting period were varied. Results of both experiments indicated that the confirmation/violation of expectancies exerted a significant impact on duration judgments. When subjects received more/fewer trials than expected or waited for a duration that was longer/shorter than expected, the total duration of these time spans was over- and underestimated, respectively. Conversely, time estimates were relatively accurate when subjects' expectancies were confirmed. The results of Experiment 1 further revealed that reaction time responses within the music perception task were also systematically influenced by the expected amount of activity. Results are discussed in terms of a framework that emphasizes the role of anticipatory attending on time estimation behavior.

Expected endings and judged duration

In four experiments, the predictions of an expectancy/contrast model (Jones & Boltz, 1989) for judged duration were evaluated. In Experiments 1 and 2, listeners estimated the relative durations of auditory pattern pairs that varied in contextual phrasing and temporal contrast. The results showed that when the second pattern of a pair either seems to (Experiments 1 and 2) or actually does (Experiment 2) end earlier (later) than the first, subjects judge it as being relatively shorter (longer). In Experiment 3, listeners heard single patterns in which notes immediately preceding the final one were omitted. Timing of the final (target) tone was varied such that it was one beat early, on time, or one beat late. Listeners' ratings of target tones revealed systematic effects of phrasing and target timing. In Experiment 4, listeners temporally completed (extrapolated) sequences of Experiment 3 that were modified to exclude the target tone. The results again showed that phrase context systematically influenced expectancies about "when" sequences should end. As a set, these studies demonstrate the effects of event structure and anticipatory attending upon experienced duration and are discussed in terms of the expectancy/contrast model.

The generation of temporal and melodic expectancies during musical listening

When listening to a melody, we are often able to anticipate not only what tonal intervals will occur next but also when in time these will appear. The experiments reported here were carried out to investigate what types of structural relations support the generation of temporal expectancies in the context of a melody recognition task. The strategy was to present subjects with a set of folk tunes in which temporal accents (i.e., notes with a prolonged duration) always occurred in the first half of a melody, so that expectancies, if generated, could carry over to an isochronous sequence of notes in the latter half of the melody. The ability to detect deviant pitch changes in the final variation as a function of rhythmic context was then evaluated. Accuracy and reaction time data from Experiment 1 indicated that expectancy formation jointly depends on an invariant periodicity of temporal accentuation and the attentional highlighting of certain melodic relations (i.e., phrase ending points). In Experiment 2, once these joint expectancies were generated, the temporal dimension had a greater facilitating effect upon melody recognition than did the melodic one. These results are discussed in terms of their implications for the perceptual processing of musical events.

Postoperative voiding interval and duration of analgesia following peripheral or caudal nerve blocks in children

We studied the time to postoperative micturition and the duration of analgesia in 82 children aged 6 mo to 10 yr undergoing herniorrhaphy or orchiopexy under general anesthesia with N2O and halothane. All received D5 lactate Ringer's solution equivalent to 6 h maintenance intraoperatively, and oral fluids postoperatively ad libitum. At the end of surgery, patients were randomly assigned to receive one of three regional anesthetic injections using 0.25% bupivacaine: caudal, 0.75 mL/kg (group I); caudal with 1:200,000 epinephrine, 0.75 mL/kg (group II); or ilioinguinaliliohypogastric nerve block with epinephrine through the wound by the surgeon (group III). Postoperatively, blinded observers scored pain at 30 min, hourly until discharge, and by telephone at 24-36 h. In the 74 patients with successful blocks (mean age 2.5 +/- 2.4 yr), the times to micturition (group I, 202 +/- 130 min; group II, 262 +/- 164 min; group III, 196 +/- 101 min) did not differ significantly among groups. Seven patients who took more than 8 h to void required no intervention. There was no difference in the numbers without pain for > or = 4 h (74%, 64%, and 69% of groups I, II, and III), or those requiring analgesics by 24 h (66% overall). The time to postoperative voiding in children is variable and not prolonged by caudal analgesia; caudal bupivacaine with or without epinephrine and ilioinguinaliliohypogastric nerve block are equally effective for postoperative analgesia.

The remembering of auditory event durations

Three experiments examined the incidental remembering of event durations. In each study, Ss engaged in an initial learning phase in which they performed a set of perceptual ratings on events for a varying number of trials. These events consisted of tonal sequences or ecological sounds that varied in their internal structure and ending. Ss were then given a surprise memory task in which they were asked to recognize the duration of each event (Experiments 1 and 3) or extrapolate its completion (Experiment 2). Results showed that in contrast to irregularly timed events, those filled with regularly timed or continuous pitch information yielded high levels of accuracy that increased with greater learning experience. In addition, durations marked by a nonarbitrary ending were more accurately remembered than those marked by an arbitrary ending which, in fact, were misremembered as shorter than their actual duration. These findings are discussed in terms of an approach that emphasizes the role of event structure on perceiving and remembering activities.

The remembering of auditory event durations

Three experiments examined the incidental remembering of event durations. In each study, Ss engaged in an initial learning phase in which they performed a set of perceptual ratings on events for a varying number of trials. These events consisted of tonal sequences or ecological sounds that varied in their internal structure and ending. Ss were then given a surprise memory task in which they were asked to recognize the duration of each event (Experiments 1 and 3) or extrapolate its completion (Experiment 2). Results showed that in contrast to irregularly timed events, those filled with regularly timed or continuous pitch information yielded high levels of accuracy that increased with greater learning experience. In addition, durations marked by a nonarbitrary ending were more accurately remembered than those marked by an arbitrary ending which, in fact, were misremembered as shorter than their actual duration. These findings are discussed in terms of an approach that emphasizes the role of event structure on perceiving and remembering activities.