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Mean Response Time (mean + response_time)
Selected AbstractsNitric oxide bioavailability modulates the dynamics of microvascular oxygen exchange during recovery from contractionsACTA PHYSIOLOGICA, Issue 2 2010D. M. Hirai Abstract Aim:, Lowered microvascular PO2 (PO2mv) during the exercise off-transient likely impairs muscle metabolic recovery and limits the capacity to perform repetitive tasks. The current investigation explored the impact of altered nitric oxide (NO) bioavailability on PO2mv during recovery from contractions in healthy skeletal muscle. We hypothesized that increased NO bioavailability (sodium nitroprusside: SNP) would enhance PO2mv and speed its recovery kinetics while decreased NO bioavailability (l -nitro arginine methyl ester: l -NAME) would reduce PO2mv and slow its recovery kinetics. Methods:,PO2mv was measured by phosphorescence quenching during transitions (rest,1 Hz twitch-contractions for 3 min,recovery) in the spinotrapezius muscle of Sprague,Dawley rats under SNP (300 ,m), Krebs-Henseleit (Control) and l -NAME (1.5 mm) superfusion conditions. Results:, Relative to recovery in Control, SNP resulted in greater overall microvascular oxygenation as assessed by the area under the PO2mv curve (PO2 AREA; Control: 3471 ± 292 mmHg s; SNP: 4307 ± 282 mmHg s; P < 0.05) and faster off-kinetics as evidenced by the mean response time (MRToff; Control: 60.2 ± 6.9 s; SNP: 34.8 ± 5.7 s; P < 0.05), whereas l -NAME produced lower PO2 AREA (2339 ± 444 mmHg s; P < 0.05) and slower MRToff (86.6 ± 14.5 s; P < 0.05). Conclusion:, NO bioavailability plays a key role in determining the matching of O2 delivery-to-O2 uptake and thus the upstream O2 pressure driving capillary-myocyte O2 flux (i.e. PO2mv) following cessation of contractions in healthy skeletal muscle. Additionally, these data support a mechanistic link between reduced NO bioavailability and prolonged muscle metabolic recovery commonly observed in ageing and diseased populations. [source] Randomized controlled trial comparing the effectiveness and safety of intranasal and intramuscular naloxone for the treatment of suspected heroin overdoseADDICTION, Issue 12 2009Debra Kerr ABSTRACT Aims Traditionally, the opiate antagonist naloxone has been administered parenterally; however, intranasal (i.n.) administration has the potential to reduce the risk of needlestick injury. This is important when working with populations known to have a high prevalence of blood-borne viruses. Preliminary research suggests that i.n. administration might be effective, but suboptimal naloxone solutions were used. This study compared the effectiveness of concentrated (2 mg/ml) i.n. naloxone to intramuscular (i.m.) naloxone for suspected opiate overdose. Methods This randomized controlled trial included patients treated for suspected opiate overdose in the pre-hospital setting. Patients received 2 mg of either i.n. or i.m. naloxone. The primary outcome was the proportion of patients who responded within 10 minutes of naloxone treatment. Secondary outcomes included time to adequate response and requirement for supplementary naloxone. Data were analysed using multivariate statistical techniques. Results A total of 172 patients were enrolled into the study. Median age was 29 years and 74% were male. Rates of response within 10 minutes were similar: i.n. naloxone (60/83, 72.3%) compared with i.m. naloxone (69/89, 77.5%) [difference: ,5.2%, 95% confidence interval (CI) ,18.2 to 7.7]. No difference was observed in mean response time (i.n.: 8.0, i.m.: 7.9 minutes; difference 0.1, 95% CI ,1.3 to 1.5). Supplementary naloxone was administered to fewer patients who received i.m. naloxone (i.n.: 18.1%; i.m.: 4.5%) (difference: 13.6%, 95% CI 4.2,22.9). Conclusions Concentrated intranasal naloxone reversed heroin overdose successfully in 82% of patients. Time to adequate response was the same for both routes, suggesting that the i.n. route of administration is of similar effectiveness to the i.m. route as a first-line treatment for heroin overdose. [source] Can First Responders Be Sent to Selected 9-1-1 Emergency Medical Services Calls without an Ambulance?ACADEMIC EMERGENCY MEDICINE, Issue 4 2003Craig B. Key MD Objectives: To evaluate the feasibility and safety of initially dispatching only first responders (FRs) to selected low-risk 9-1-1 requests for emergency medical services. First responders are rapidly-responding fire crews on apparatus without transport capabilities, with firefighters trained to at least a FR level and in most cases to the basic emergency medical technician (EMT) level. Low-risk 9-1-1 requests include automatic medical alerts (ALERTs), motor vehicle incidents (MVIs) for which the caller was unable to answer any medical dispatch questions designed to prioritize the call, and 9-1-1 call disconnects (D/Cs). Methods: A before-and-after study of patient dispositions was conducted using historical controls for comparison. During the historical control phase of six months, one year prior to the study phase, basic life support ambulances (staffed with two basic EMTs) were dispatched to selected low-risk 9-1-1 incidents. During the six-month study phase, a fire FR crew equipped with automated external defibrillators (AEDs) was sent initially without an ambulance to these incidents. Results: For ALERTs (n= 290 in historical group vs. 330 in study group), there was no statistical difference in the transport rate (7% vs 10%), but there was a statistically significant increase in the follow-up use of advanced life support (ALS) (1% vs 4%, p = 0.009). No patient in the ALERTs historical group required airway management, while one patient in the study group received endotracheal intubation. No patient required defibrillation in either group. Analysis of the MVIs showed a significant decrease (p < 0.0001) in the patient transport rate from 39% of controls to 33% of study patients, but no change in the follow-up use of ALS interventions (2% for each group). For both the ALERTs and MVIs, the FR's mean response time was faster than ambulances (p < 0.0001). Among the 9-1-1 D/Cs with FRs only (n= 1,028), 15% were transported and 43 (4%) received subsequent ALS care. Four of these patients (0.4%) received intubation and two (0.2%) required defibrillation. However, no patient was judged to have had adverse outcomes as a result of the dispatch protocol change. Conclusions: Fire apparatus crews trained in the use of AEDs can safely be used to initially respond alone (without ambulances) to selected, low-risk 9-1-1 calls. This tactic improves response intervals while reducing ambulance responses to these incidents. [source] Dynamics of skeletal muscle oxygenation during sequential bouts of moderate exerciseEXPERIMENTAL PHYSIOLOGY, Issue 3 2005Leonardo F. Ferreira In rat muscle, faster dynamics of microvascular PO2 (approximately blood flowto O2 uptakeratio) after prior contractions that did not alter blood [lactate] have been considered to be a consequence of fasterkinetics. However, in humans, prior exercise below the lactate threshold does not affect the pulmonarykinetics. To clarify this apparent discrepancy, we examined the effects of prior moderate exercise on the kinetics of muscle oxygenation (deoxyhaemoglobin, [HHb],) and pulmonaryin humans. Eight subjects performed two bouts (6 min each) of moderate-intensity cycling separated by 6 min of baseline pedalling. Muscle (vastus lateralis) oxygenation was evaluated by near-infrared spectroscopy andwas measured breath-by-breath. The time constant (,) of the primary component ofwas not significantly affected by prior exercise (21.5 ± 9.2 versus 25.6 ± 9.7 s; Bout 1 versus 2, P= 0.49). The time delay (TD) of [HHb] decreased (11.6 ± 2.6 versus 7.7 ± 1.5 s; Bout 1 versus 2, P < 0.05) and ,[HHb] increased (7.0 ± 3.5 versus 10.2 ± 4.6 s; Bout 1 versus 2, P < 0.05), while the mean response time (TD +,) did not change (18.6 ± 2.7 versus 17.9 ± 3.9 s) after prior moderate exercise. Thus, prior moderate exercise resulted in shorter onset and slower rate of increase in [HHb] during subsequent exercise. These data suggest that prior exercise altered the dynamic interaction betweenandfollowing the onset of exercise. [source] Class-based weighted fair queueing: validation and comparison by trace-driven simulationINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2005Rachid El Abdouni Khayari Abstract World-wide web as well as proxy servers rely for their scheduling on services provided by the underlying operating system. In practice, this means that some form of first-come-first-served (FCFS) scheduling is utilized. Although FCFS is a reasonable scheduling strategy for job sequences that do not show much variance, for the world-wide web it has been shown that the requested-object sizes do exhibit heavy tails. Under these circumstances, job scheduling on the basis of shortest-job first (SJF) or shortest remaining processing time (SRPT) has been shown to minimize the total average waiting time. However, these methods have the disadvantage of potential job starvation. In order to avoid the problems of both FCFS and SJF we present in this paper a new scheduling approach called class-based interleaving weighted fair queueing (CI-WFQ). This scheduling approach exploits the specific characteristics of the job stream being served, that is, the distribution of the sizes of the objects being requested, to set its parameters such that good mean response times are obtained and starvation does not occur. In that sense, the new scheduling strategy can be made adaptive to the characteristics of the job stream being served. In this paper we compare the new scheduling approach (using trace-driven simulations) to FCFS, SJF and the recently introduced ,-scheduling, and show that CI-WFQ combines very good performance (as far as mean and variance of response time and blocking probability are concerned) with a scheduling complexity almost as low as for FCFS (and hence, lower than for SJF and ,-scheduling). The use of trace-driven simulation is essential, since the special properties of the arrival process makes analytical solutions very difficult to achieve. Copyright © 2005 John Wiley & Sons, Ltd. [source] A simple two-stage model predicts response time distributionsTHE JOURNAL OF PHYSIOLOGY, Issue 16 2009R. H. S. Carpenter The neural mechanisms underlying reaction times have previously been modelled in two distinct ways. When stimuli are hard to detect, response time tends to follow a random-walk model that integrates noisy sensory signals. But studies investigating the influence of higher-level factors such as prior probability and response urgency typically use highly detectable targets, and response times then usually correspond to a linear rise-to-threshold mechanism. Here we show that a model incorporating both types of element in series , a detector integrating noisy afferent signals, followed by a linear rise-to-threshold performing decision , successfully predicts not only mean response times but, much more stringently, the observed distribution of these times and the rate of decision errors over a wide range of stimulus detectability. By reconciling what previously may have seemed to be conflicting theories, we are now closer to having a complete description of reaction time and the decision processes that underlie it. [source] | |||||||||||||