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PubMed2006

Improving communication skills: feedback from faculty and residents.

OBJECTIVES: To determine common themes in faculty and peer feedback for emergency medicine (EM) resident oral presentations. METHODS: From January to July 2005, all EM residents received written feedback on communication skills from two faculty and two peer reviewers. The feedback forms were analyzed by using formal grounded theory. The two investigators independently reviewed 25% of the forms to generate a code of general categories and specific qualifiers. The independent codes were merged by consensus into a common code. All forms were independently coded by the two investigators using the common code. Coding disagreements were resolved by consensus, yielding a uniform inventory of feedback categories and qualifiers. RESULTS: Twenty-one of 23 residents participated. Three hundred seventy-two data points were coded, with an interrater agreement of 85.7%. The five most common feedback themes were as follows: focus on key and relevant teaching points; increase audience participation; encourage higher level thinking; decrease content per slide; and add missing content relevant to teaching point. Peers differed from faculty, mentioning more frequently encourage higher level thinking and add missing content relevant to teaching point. Faculty differed from peers, mentioning increase clarity of teaching point and be engaging and enthusiastic more frequently. The difference in distribution of themes between faculty and peers was significant (chi2 = 59.692; p = 0.01). CONCLUSIONS: The authors present a model for providing feedback to EM residents on communication skills that is individualized, behavior based, and includes peer comments. Faculty and peers differ in their recommendations. The findings may inform communication skills curricula for EM residents.

Communication↗
PubMed1997

Effects of positive feedback on the social interactions of boys with attention deficit hyperactivity disorder: a test of the self-protective hypothesis.

Tested the hypothesis that inflated self-assessments offered by children with attention deficit hyperactivity disorder (ADHD) serve a self-protective function. This was accomplished by examining the effects of positive feedback on self-perceptions and social interactions of boys with ADHD and comparison boys. Boys with ADHD and comparison boys, 8 to 11 years old, were paired in 60 dyads and interacted in two unstructured cooperative tasks. Following the first interaction, 1 boy in half of the dyads received positive feedback, supposedly from his partner, concerning his performance. Results indicated that following the first interaction, but prior to feedback, boys with ADHD had an overly positive view of how much their partner liked them. However, following the second interaction, boys with ADHD who received positive feedback actually showed a significant decrease in their self-perceptions, whereas comparison boys who received feedback showed an increase. These results are seen as supportive of the self-protective hypothesis that children with ADHD offer inflated self-perceptions to counter feelings of inadequacy. When presented with positive feedback, they are able to relax this defensive posture and offer more realistic self-assessments.

Attention Deficit Disorder with Hyperactivity↗
PubMed1984

Evidence from the rhesus monkey (Macaca mulatta) for the view that negative feedback control of luteinizing hormone secretion by the testis is mediated by a deceleration of hypothalamic gonadotropin-releasing hormone pulse frequency.

The site and mode of the feedback actions of testicular hormones on gonadotropin secretion in the adult rhesus monkey were investigated using the arcuate-lesioned preparation previously employed by others to study cognate problems in the female. The negative feedback loop that governs LH and FSH release in the male monkey was opened without changing either the frequency or amplitude of intermittent GnRH stimulation of the pituitary gonadotrophs, which was clamped by exogenous GnRH replacement at a level that approximated the intact or closed loop hypophysiotropic signal. In this manner, the relative importance of adenohypophysial vs. hypothalamic sites of feedback action of testicular hormones on LH and FSH secretion was assessed. To accomplish the foregoing, radiofrequency lesions were placed in the region of the arcuate nucleus to abolish endogenous hypothalamic GnRH secretion. Patterns of temporally coupled episodes of pituitary LH and testicular testosterone discharge that in nonlesioned animals characteristically occur, on the average, once every 3 h throughout the 24-h light-dark cycle were restored in lesioned animals by an intermittent iv infusion of GnRH (0.1 micrograms/min for 3 min every 3 h). Bilateral orchidectomy in this experimental paradigm elicited only small increments in LH pulse amplitude and mean plasma LH concentration, a response in striking contrast to the dramatic postcastration LH hypersecretion observed in animals with intact hypothalami that respond to the opening of the negative feedback loop with an apparent acceleration in the endogenous frequency of intermittent GnRH secretion. A marked rise in mean plasma LH concentration in arcuate-lesioned males, however, was forth-coming when the frequency of intermittent exogenous GnRH stimulation was increased 2-3 weeks after castration from one pulse every 3 h (intact frequency) to one pulse per h (castrate frequency). These findings fail to provide evidence for a major inhibitory feedback action of the testes on LH secretion at the level of the adenohypophysis. They are entirely consistent, however, with the hypothesis that the negative feedback control of LH release by the male gonad is mediated, principally, via the central nervous system by an action of testicular hormone, most probably testosterone, to retard the frequency of the neural timing mechanism that governs the intermittent pattern of GnRH release by the hypothalamus.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1986

Reset of feedback in the adrenocortical system: an apparent shift in sensitivity of adrenocorticotropin to inhibition by corticosterone between morning and evening.

There is evidence in man and rats that higher circulating levels of glucocorticoids are required to normalize basal unstimulated ACTH levels at the peak of the circadian rhythm than at the trough. To explore this phenomenon, we tested the inhibitory effect of constant levels of corticosterone on plasma ACTH in the morning (AM) and evening (PM) in young male rats implanted with fused pellets of corticosterone-cholesterol at the time of adrenalectomy (ADX+B) and studied 5 days later. There was a marked shift of the plasma corticosterone-ACTH inhibition curve to the right between AM and PM, demonstrating that the efficacy of corticosterone feedback inhibition of ACTH is less in the PM. Comparison of plasma ACTH and corticosterone levels during 24 h in sham-adrenalectomized rats (SHAM-ADX), adrenalectomized rats (ADX), and ADX+B revealed constantly low ACTH in SHAM-ADX, constantly high ACTH in ADX, and biphasic ACTH levels in ADX+B. Corticosterone levels were biphasic in SHAM-ADX and were constant in the other two groups. These results again showed a shift in corticosterone feedback efficacy as a function of the time of day and also suggested that basal ACTH secretion is maintained in the low normal range in intact rats because of the marked diurnal rhythm in corticosterone. The sensitivity of the pituitary ACTH response to exogenous CRF did not change between AM and PM in either intact or ADX+B showing that the shift in feedback sensitivity to corticosterone does not reside in the pituitary. The response of the entire adrenocortical system to histamine stress was shown to be equivalent in both the AM and PM, suggesting that feedback sensitivity of the entire system to corticosterone does not change as a function of the time of day. We conclude from these results that there is an apparent diurnal change in ACTH sensitivity to corticosterone feedback that can be defined operationally as reset. We believe that the site of feedback being tested shifts solely from the pituitary in the AM (at the nadir of the rhythm) to the brain and the pituitary in the PM (at the peak of the rhythm). The lack of the normally high transients of corticosterone that occur in SHAM-ADX rats results in increased brain drive of the pituitary in ADX+B.

Adrenal Cortex↗
PubMed1998

On the mechanism of the positive feedback action of estradiol on luteinizing hormone secretion in the rhesus monkey.

In women and rhesus monkeys, both the negative and positive feedback actions of estradiol (E2) on gonadotropin secretion (inhibition followed by a surge) can be exerted directly at the level of the pituitary gland. We have tested the hypothesis that the positive feedback action of E2 represents but an "escape" from its negative feedback inhibition of gonadotropin secretion consequent to a desensitization of the gonadotropes occasioned by sustained exposure to elevated concentrations of the steroid. We have attempted to replicate such a desensitization by blocking the negative feedback action of E2 by the administration of a potent estrogen receptor antagonist devoid of any agonistic properties (ZM 182,780) to rhesus monkeys in the midfollicular phase of the menstrual cycle (n = 14). The estrogen antagonist, administered at a dose that in separate experiments completely blocked both the negative and the positive feedback effect of exogenous E2 on pituitary LH secretion, failed to produce a surge-like increase in serum LH concentrations. The present results do not support the hypothesis that the LH surge is the consequence of the removal of the negative feedback action of E2. Evidence is presented that ZM 182,780, in contrast to its inhibition of E2-induced LH surges, cannot block the inhibition of hypothalamic GnRH pulse generator activity by E2.

Animals↗
PubMed2001

Corticotropin secretory dynamics in humans under low glucocorticoid feedback.

To explore the mechanisms of homeostatic adaptation of the hypothalamo-pituitary-adrenal axis to an experimental low-feedback condition, we quantitated pulsatile (ultradian), entropic (pattern-sensitive), and 24-h rhythmic (circadian) ACTH secretion during high-dose metyrapone blockade (2 g orally every 2 h for 12 h, and then 1 g every 2 h for 12 h). Plasma ACTH and cortisol concentrations were sampled concurrently every 10 min for 24 h in nine adults. The metyrapone regimen reduced the amplitude of nyctohemeral cortisol rhythm by 45% (P = 0.0013) and delayed the time of the cortisol maximum (acrophase) by 7.1 h (P = 0.0002). Attenuated cortisol negative feedback stimulated a 7-fold increase in the mean (24-h) plasma ACTH concentration, which rose from 24 +/- 1.6 to 169 +/- 31 pg/ml (ng/liter) (P < 0.0001). Augmented ACTH output was driven by a 12-fold amplification of ACTH secretory burst mass (integral of the underlying secretory pulse) (21 +/- 3.1 to 255 +/- 64 pg/ml; P < 0.0001), yielding a higher percentage of ACTH secreted in pulses (53 +/- 3.5 vs. 92 +/- 1.3%; P < 0.0001). There were minimal elevations in basal (nonpulsatile) ACTH secretion (by 50%; P = 0.0049) and ACTH secretory burst frequency (by 36%; P = 0.031). The estimated half-life of ACTH (median, 22 min) and the calculated ACTH secretory burst half-duration (pulse event duration at half-maximal amplitude) (median, 23 min) did not change. Hypocortisolemia evoked remarkably more orderly subordinate patterns of serial ACTH release, as quantitated by the approximate entropy statistic (P = 0.003). This finding was explained by enhanced regularity of successive ACTH secretory pulse mass values (P = 0.032). In contrast, there was no alteration in serial ACTH interpulse-interval (waiting-time) regularity. At the level of 24-h ACTH rhythmicity, cortisol withdrawal enhanced the daily rhythm in ACTH secretory burst mass by 29-fold, elevated the mesor by 16-fold, and delayed the acrophase by 3.4 h from 0831 h to 1154 h (each P < 10(-3)). In summary, short-term glucocorticoid feedback deprivation primarily (>97% of effect) amplifies pulsatile ACTH secretory burst mass, while minimally elevating basal/nonpulsatile ACTH secretion and ACTH pulse frequency. Reduced cortisol feedback paradoxically elicits more orderly (less entropic) patterns of ACTH release due to emergence of more regular ACTH pulse mass sequences. Cortisol withdrawal concurrently heightens the amplitude and mesor of 24-h rhythmic ACTH release and delays the timing of the ACTH acrophase. In contrast, the duration of underlying ACTH secretory episodes is not affected, which indicates that normal pulse termination may be programmed centrally rather than imposed by rapid negative feedback. Accordingly, we hypothesize that adrenal glucocorticoid negative feedback controls hypothalamo-pituitary-adrenal axis dynamics via the 3-fold distinct mechanisms of repressing the mass of ACTH secretory bursts, reducing the orderliness of the corticotrope release process, and modulating the intrinsic diurnal rhythmicity of the hypothalamo-corticotrope unit.

Adrenocorticotropic Hormone↗
PubMed1988

Feedback regulators in normal and tumour tissues.

Regulation of cell behaviour and population size is presumed to be not unlike classical regulation in non-biological systems, i.e. it is controlled by the cybernetic principle of negative feedback whereby the performance of progenitor cells depends inversely on a signal from their product, the size of which is proportional to the mass of the product. This signal may be inhibitory, acting directly on the progenitor cells. Alternatively, it may operate via an indirect and integrated inhibitor/stimulator feedback loop in which the one influences the production of the other. Illustrations taken from the various phases of haemopoietic development show the operation of these loops. Haemopoietic stem cells are under the direct influence of both inhibitor and stimulator but it is a feedback signal from the stem cell population that dictates the production of the one rather than the other. A second inhibitor acting at the stem cell level is a low molecular weight tetrapeptide which blocks the entry of cells into DNA synthesis, thus protecting them during a regimen of treatment with an S-phase cytotoxic drug. Proliferation of the maturing cells is also inhibited by feedback products of their fully mature descendants. Here, the effect is one of cell cycle modulation, whereas in the stem cell population the inhibitor and stimulator effect an on/off switch. Attempts to characterize the molecules involved have been limited. A series of tri- to pentapeptides has been described for haemopoietic or epithelial cell inhibitors. A common feature of several is a pGlu-Glu end though whether this has any significance is not known. In tumours it has been shown that some ascites are self-limiting and treatment of small tumours with cell-free fluid from a mature growth blocks their further growth. It appears that many tumour cells produce the feedback signals characteristic of their normal counterparts but are themselves less sensitive to it. The same is true of transforming growth factor-beta which is produced and detected by virtually all cell types. In this case, the factor, inhibiting in most cases, is produced in inactive form and achieves its target specificity by a localized capacity to activate it. Some tumours, while responding to exogenous active TGF-beta are incapable of activating the latent molecule. It is concluded that the differential sensitivity of normal and neoplastic tissues to physiological feedback regulators is a potentially exploitable property in cancer therapy.

Cell Division↗
PubMed2003

Pharmacological modulation of local feedback mechanisms as a therapeutic approach in breast cancer treatment.

Breast function and development are regulated by a network of local and systemic signals which can exert either stimulatory or inhibitory effects. Many of these signals are mediated by topically produced hormones and cytokines, which are both believed to be part of complex feedback loops. Over the last few years it has become increasingly clear that local feedback mechanisms also play an integral part in the growth and local invasion of malignant breast tumors. The intratumoral development of positive feedback loops can not only enhance the malignant phenotype and growth rate of tumor cells, but is also thought to stimulate the formation of vascular elements to ensure a sufficient supply of nutrients. In addition, the disruption of physiological negative feedback loops in breast tissue might result in the loss of cell cycle control and eventually lead to increased tumor growth and local breakdown of adjacent stroma. It is therefore not surprising that many of these loops involve interactions between tumor cells and their stromal environment, and are located at the site of tumor invasion. Since several of the potentially involved cytokines are already known and a number of specific inhibitors are now available, it is possible to interrupt pathological intercellular communication by selectively inhibiting intratumoral key feedback mechanisms. While the identification of each new intratumoral feedback loop can help us in our quest for for novel specific antineoplastic strategies, we now also know that some of the most commonly used endocrine therapies are probably so effective because they also interfere with local intercellular communication.

Breast Neoplasms↗
PubMed2001

Haptic force-feedback devices for the office computer: performance and musculoskeletal loading issues.

Pointing devices, essential input tools for the graphical user interface (GUI) of desktop computers, require precise motor control and dexterity to use. Haptic force-feedback devices provide the human operator with tactile cues, adding the sense of touch to existing visual and auditory interfaces. However, the performance enhancements, comfort, and possible musculoskeletal loading of using a force-feedback device in an office environment are unknown. Hypothesizing that the time to perform a task and the self-reported pain and discomfort of the task improve with the addition of force feedback, 26 people ranging in age from 22 to 44 years performed a point-and-click task 540 times with and without an attractive force field surrounding the desired target. The point-and-click movements were approximately 25% faster with the addition of force feedback (paired t-tests, p < 0.001). Perceived user discomfort and pain, as measured through a questionnaire, were also smaller with the addition of force feedback (p < 0.001). However, this difference decreased as additional distracting force fields were added to the task environment, simulating a more realistic work situation. These results suggest that for a given task, use of a force-feedback device improves performance, and potentially reduces musculoskeletal loading during mouse use. Actual or potential applications of this research include human-computer interface design, specifically that of the pointing device extensively used for the graphical user interface.

Adult↗
PubMed2005

Proton-mediated feedback inhibition of presynaptic calcium channels at the cone photoreceptor synapse.

Generation of center-surround antagonistic receptive fields in the outer retina occurs via inhibitory feedback modulation of presynaptic voltage-gated calcium channels in cone photoreceptor synaptic terminals. Both conventional and unconventional neurotransmitters, as well as an ephaptic effect, have been proposed, but the intercellular messaging that mediates the inhibitory feedback signal from postsynaptic horizontal cells (HCs) to cones remains unknown. We examined the possibility that proton concentration in the synaptic cleft is regulated by HCs and that it carries the feedback signal to cones. In isolated, dark-adapted goldfish retina, we assessed feedback in the responses of HCs to light and found that strengthened pH buffering reduced both rollback and the depolarization to red light. In zebrafish retinal slices loaded with Fluo-4, depolarization with elevated K(+) increased Ca signals in the synaptic terminals of cone photoreceptors. Kainic acid, which depolarizes HCs but has no direct effect on cones, depressed the K(+)-induced Ca signal, whereas CNQX, which hyperpolarizes HCs, increased the Ca signals, suggesting that polarization of HCs alters inhibitory feedback to cones. We found that these feedback signals were blocked by elevated extracellular pH buffering, as well as amiloride and divalent cations. Voltage clamp of isolated HCs revealed an amiloride-sensitive conductance that could mediate modulation of cleft pH dependent on the membrane potential of these postsynaptic cells.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1998

Role of feedback in formation of acute tolerance to alcohol.

OBJECTIVE: The contributions of feedback to formation of acute ethanol tolerance were studied during performance of a task that allowed practice in the absence of feedback about performance accuracy. METHOD: The perceptual instability of the seen environment during head movement (apparent concomitant motion, ACM) and the vestibulo-ocular reflex (VOR) were measured before and after alcohol ingestion. In separate conditions, eight (six female) subjects were either deprived or not deprived of normal vision of the laboratory during the portion of the experiment following onset of alcohol ingestion. RESULTS: Alcohol caused ACM in the direction opposite head rotation to increase in both sessions. The degree of ACM increase was greater during sessions in which visual feedback was prevented than in sessions in which subjects could see the surroundings. The increase in ACM was accompanied by a decrease in gain of the VOR which was relatively larger in the no-feedback condition. In addition, ACM returned to normal (pre-alcohol ingestion) values more rapidly during sessions in which subjects received visual feedback. CONCLUSIONS: The results suggest that feedback is an important component in forming acute tolerance to alcohol, independent of task practice.

Adult↗
PubMed1984

An evaluation of the electronic fetal monitor as a feedback device during labor.

We describe new methodology for the evaluation of the labor experience and preliminary findings using these methods. The effects of feedback from an Electronic Fetal Monitor on report of contraction onset were evaluated during the labors of eight primiparous women, four of whom had attended childbirth preparation classes. Using a within-subject reversal design, data were gathered across four phases for each woman: no feedback (monitor turned away from mother and coach), feedback, no feedback, and feedback again. The women were observed in early labor without medication. Six women were able to note the onset of contractions earlier with the availability of feedback; two women (who had not attended childbirth preparation classes) were more variable in their response. Threshold for recognition of pain onset did not change reliably. Seven of the eight women chose to continue monitoring when offered the chance to discontinue it. These results suggest that the technological advance of fetal monitoring can be used in cooperation with prepared childbirth techniques to facilitate earlier recognition of contraction onset, allowing increased preparation for contractions. Further experimental evaluations during labor are suggested.

Adolescent↗
PubMed1992

Promoting stimulus control with textual prompts and performance feedback for persons with mild disabilities.

We assessed whether written task analyses would serve as textual prompts for performing functional tasks by persons with mild disabilities. Several variables that could influence the effectiveness of textual prompts to promote stimulus control were examined across four groups. A consistent finding was that written specific task analyses combined with end-of-trial performance feedback were effective for promoting the acquisition and generalization of several tasks. Performance transferred immediately to natural discriminative stimuli when the written task analyses and feedback were withdrawn for most tasks and participants. For 2 participants, transfer of stimulus control was accomplished by prompt fading, using individualized written task analyses either with or without performance feedback (Group 1). When feedback was not provided, the effectiveness of written specific task analyses was inconsistent across groups. In contrast to the controlling effects of written specific task analyses, written generic task analyses, which specified only major task outcomes, when combined with performance feedback (Group 1) did not control responding. Overall, this research demonstrated the effectiveness of written specific task analyses and performance feedback to promote stimulus control for persons with mild disabilities.

Activities of Daily Living↗
PubMed2005

Effects of immediate performance feedback on implementation of behavior support plans.

Research has focused on increasing the treatment integrity of school-based interventions by utilizing performance feedback. The purpose of this study was to extend this literature by increasing special education teachers' treatment integrity for implementing antecedent and consequence procedures in an ongoing behavior support plan. A multiple baseline across teacher-student dyads (for two classrooms) design was used to evaluate the effects of performance feedback on the percentage of antecedent and consequence components implemented correctly during 1-hr observation sessions. Performance feedback was provided every other week for 8 to 22 weeks after a stable or decreasing trend in the percentage of antecedent or consequence components implemented correctly. Results suggested that performance feedback increased the treatment integrity of antecedent components for 4 of 5 teachers and consequence components for all 5 teachers. These results were maintained following feedback for all teachers across antecedent and consequence components. Teachers rated performance feedback favorably with respect to the purpose, procedures, and outcome, as indicated by a social validity rating measure.

Adolescent↗
PubMed1986

Variable-ratio schedules as variable-interval schedules with linear feedback loops.

The mathematical theory of linear systems has been used successfully to describe responding on variable-interval (VI) schedules. In the simplest extension of the theory to the variable-ratio (VR) case, VR schedules are treated as if they were VI schedules with linear feedback loops. The assumption entailed by this approach, namely, that VR and VI-plus-linear-feedback schedules are equivalent, was tested by comparing responding on the two types of schedule. Four human subjects' lever pressing produced monetary reinforcers on five VR schedules, and on five VI schedules with linear feedback loops that reproduced the feedback properties of the VR schedules. Pressing was initiated by instructions in 2 subjects, and was shaped by successive approximation in the other 2. The different methods of response initiation did not have differential effects on behavior. For each of the 4 subjects, the VR and the comparable VI-plus-linear-feedback schedules generated similar average response rates and similar response patterns. The subjects' behavior on both types of schedule was similar to that of avian and rodent species on VR schedules. These results indicate that the assumption entailed by the VI-plus-linear-feedback approach to the VR case is valid and, consequently, that the approach is worth pursuing. The results also confute interresponse-time theories of schedule performance, which require interval and ratio contingencies to produce different response rates.

Adult↗
PubMed2006

Feedback functions, optimization, and the relation of response rate to reinforcer rate.

The present experiment arranged a series of inverted U-shaped feedback functions relating reinforcer rate to response rate to test whether responding was consistent with an optimization account or with a one-to-one relation of response rate to reinforcer rate such as linear system theory's rate equation or Herrnstein's hyperbola. Reinforcer rate was arranged according to a quadratic equation with a maximum at a unique response rate. The experiment consisted of two phases, during which 6 Long Evans rats lever pressed for food. In the first phase of the experiment, the rats responded on six fixed-interval-plus-quadratic-feedback schedules, and in the second phase the rats responded on three variable-interval-plus-quadratic-feedback schedules. Responding in both phases was inconsistent with a one-to-one relation of response rate to reinforcer rate. Instead, different response rates were obtained at equivalent reinforcer rates. Responding did vary directly with the vertex of the feedback function in both phases, a finding consistent with optimization of reinforcer rate. The present results suggest that the feedback function relating reinforcer rate to response rate imposed by a reinforcement schedule can be an important determinant of behavior. Furthermore, the present experiment illustrates the benefit of arranging feedback functions to investigate assumptions about the variables that control schedule performance.

Animals↗
PubMedDate not supplied

Feedback control methods for drug dosage optimisation. Concepts, classification and clinical application.

The concept of feedback control methods for drug dosage optimisation is described from the viewpoint of control theory. The control system consists of 5 parts: (a) patient (the controlled process); (b) response (the measured feedback); (c) model (the mathematical description of the process); (d) adaptor (to update the parameters); and (e) controller (to determine optimum dosing strategy). In addition to the conventional distinction between open-loop and closed-loop control systems, a classification is proposed for dosage optimisation techniques which distinguishes between tight-loop and loose-loop methods depending on whether physician's interaction is absent or included as part of the control step. Unlike engineering problems where the process can usually be controlled by fully automated devices, therapeutic situations often require that the physician be included in the decision-making process to determine the 'optimal' dosing strategy. Tight-loop and loose-loop methods can be further divided into adaptive and non-adaptive, depending on the presence of the adaptor. The main application areas of tight-loop feedback control methods are general anaesthesia, control of blood pressure, and insulin delivery devices. Loose-loop feedback methods have been used for oral anticoagulation and in therapeutic drug monitoring. The methodology, advantages and limitations of the different approaches are reviewed. A general feature common to all application areas could be observed: to perform well under routine clinical conditions, which are characterised by large interpatient variability and sometimes also intrapatient changes, control systems should be adaptive. Apart from application in routine drug treatment, feedback control methods represent an important research tool. They can be applied for the investigation of pathophysiological and pharmacodynamic processes. A most promising application is the evaluation of the relationship between an intermediate response (e.g. drug level), which is often used as feedback for dosage adjustment, and the final therapeutic goal.

Anesthetics↗
PubMed2005

Accelerometer feedback to promote physical activity in adults with type 2 diabetes: a pilot study.

This study examined whether giving activity feedback to obese, sedentary adults with Type 2 diabetes would improve their adherence to a home-based walking program. 49 subjects were recruited. Ten failed a treadmill cardiovascular test. Another 9 dropped out before the intervention, and 4 dropped out during the intervention. The remaining 26 adults (14 women, 12 men; age M = 48.1 yr., SD = 7.1) received behavioral counseling monthly for 3 mo. regarding exercise. All subjects wore a triaxial accelerometer during these 3 months. Randomly, half of the subjects were blind to the data from the accelerometers, i.e., no feedback, and had counseling based on their self-report diaries. The other half had access to the accelerometer data, got a computerized graph of their physical activity for the period between counseling sessions, and had counseling based on these objective data, i.e., feedback. The feedback group showed an increase in exercise over the 3 mo. The nonfeedback group showed an increase in activity at 1.5 mo. but reverted to their baseline exercise levels at 3 mo. However, analysis of variance showed there was at least an 8% probability that this effect was due to chance, so the hypothesis that feedback would improve exercise adherence could not be supported. Further studies with larger sample sizes and greater control of experimental conditions are needed to determine the utility of objective activity feedback.

Adult↗