Changes In Physiological Variables Research Articles

Practice Variation in Spontaneous Breathing Trial Performance and Reporting.

Background. Spontaneous breathing trials (SBTs) are standard of care in assessing extubation readiness; however, there are no universally accepted guidelines regarding their precise performance and reporting. Objective. To investigate variability in SBT practice across centres. Methods. Data from 680 patients undergoing 931 SBTs from eight North American centres from the Weaning and Variability Evaluation (WAVE) observational study were examined. SBT performance was analyzed with respect to ventilatory support, oxygen requirements, and sedation level using the Richmond Agitation Scale Score (RASS). The incidence of use of clinical extubation criteria and changes in physiologic parameters during an SBT were assessed. Results. The majority (80% and 78%) of SBTs used 5 cmH2O of ventilator support, although there was variability. A significant range in oxygenation was observed. RASS scores were variable, with RASS 0 ranging from 29% to 86% and 22% of SBTs performed in sedated patients (RASS < −2). Clinical extubation criteria were heterogeneous among centres. On average, there was no change in physiological variables during SBTs. Conclusion. The present study highlights variation in SBT performance and documentation across and within sites. With their impact on the accuracy of outcome prediction, these results support efforts to further clarify and standardize optimal SBT technique.

Addition of magnesium sulphate to ropivacaine for spinal analgesia in dogs undergoing tibial plateau levelling osteotomy

The aim of this blinded, randomised, prospective clinical trial was to determine whether the addition of magnesium sulphate to spinally-administered ropivacaine would improve peri-operative analgesia without impairing motor function in dogs undergoing orthopaedic surgery. Twenty client-owned dogs undergoing tibial plateau levelling osteotomy were randomly assigned to one of two treatment groups: group C (control, receiving hyperbaric ropivacaine by the spinal route) or group M (magnesium, receiving a hyperbaric combination of magnesium sulphate and ropivacaine by the spinal route). During surgery, changes in physiological variables above baseline were used to evaluate nociception. Arterial blood was collected before and after spinal injection, at four time points, to monitor plasma magnesium concentrations. Post-operatively, pain was assessed with a modified Sammarco pain score, a Glasgow pain scale and a visual analogue scale, while motor function was evaluated with a modified Tarlov scale. Assessments were performed at recovery and 1, 2 and 3 h thereafter. Fentanyl and buprenorphine were administered as rescue analgesics in the intra- and post-operative periods, respectively.Plasma magnesium concentrations did not increase after spinal injection compared to baseline. Group M required less intra-operative fentanyl, had lower Glasgow pain scores and experienced analgesia of longer duration than group C (527.0 ± 341.0 min vs. 176.0 ± 109.0 min). However, in group M the motor block was significantly longer, which limits the usefulness of magnesium for spinal analgesia at the investigated dose. Further research is needed to determine a clinically effective dose with shorter duration of motor block for magnesium used as an additive to spinal analgesic agents.

Clinical and Physiological Events That Contribute to the Success Rate of Finding "Optimal" Cerebral Perfusion Pressure in Severe Brain Trauma Patients.

Recently, a concept of an individually targeted level of cerebral perfusion pressure that aims to restore impaired cerebral vasoreactivity has been advocated after traumatic brain injury. The relationship between cerebral perfusion pressure and pressure reactivity index normally is supposed to have a U-shape with its minimum interpreted as the value of "optimal" cerebral perfusion pressure. The aim of this study is to investigate the relation between the absence of the optimal cerebral perfusion pressure curve and physiological variables, clinical factors, and interventions. Retrospective analysis of prospectively collected data. Neurocritical care units in two university centers. Between May 2012 and December 2013, a total of 48 traumatic brain injury patients were studied with real-time annotation of predefined clinical events. None. All patients had continuous monitoring of arterial blood pressure, intracranial pressure, and cerebral perfusion pressure, with real-time calculations of pressure reactivity index and optimal cerebral perfusion pressure using ICM+ software (Cambridge Enterprise, University of Cambridge, Cambridge, UK). Selected clinical events were inserted on a daily basis, including changes in physiological variables, sedativeanalgesic drugs, vasoactive drugs, and medical/surgical therapies for intracranial hypertension. The collected data were divided into 4-hour periods, with the primary outcome being absence of the optimal cerebral perfusion pressure curve. For every period, mean values (± SDs) of arterial blood pressure, intracranial pressure, pressure reactivity index, and other physiological variables were calculated; clinical events were organized using predefined scales. In 28% of all 1,561 periods, an optimal cerebral perfusion pressure curve was absent. A generalized linear mixed model with binary logistic regression was fitted. Absence of slow arterial blood pressure waves (odds ratio, 2.7; p < 0.001), higher pressure reactivity index values (odds ratio, 2.9; p < 0.001), lower amount of sedative-analgesic drugs (odds ratio, 1.9; p = 0.03), higher vasoactive medication dose (odds ratio, 3.2; p = 0.02), no administration of maintenance neuromuscular blockers (odds ratio, 1.7; p < 0.01), and following decompressive craniectomy (odds ratio, 1.8; p < 0.01) were independently associated with optimal cerebral perfusion pressure curve absence. This study identified six factors that were independently associated with absence of optimal cerebral perfusion pressure curves.

Nerve stimulator-guided sciatic-femoral nerve block in raptors undergoing surgical treatment of pododermatitis

ObjectiveTo describe the nerve stimulator-guided sciatic-femoral nerve block in raptors undergoing surgical treatment of pododermatitis. Study designProspective clinical trial. AnimalsFive captive raptors (Falco peregrinus) aged 6.7 ± 1.3 years. MethodsAnaesthesia was induced and maintained with isoflurane in oxygen. The sciatic-femoral nerve block was performed with 2% lidocaine (0.05 mL kg−1 per nerve) as the sole intra-operative analgesic treatment. Intraoperative physiological variables were recorded every 10 minutes from endotracheal intubation until the end of anaesthesia. Assessment of intraoperative nociception was based on changes in physiological variables above baseline values, while evaluation of postoperative pain relied on species-specific behavioural indicators. ResultsThe sciatic-femoral nerve block was feasible in raptors and the motor responses following electrical stimulation of both nerves were consistent with those reported in mammalian species. During surgery no rescue analgesia was required. The anaesthesia plane was stable and cardiorespiratory variables did not increase significantly in response to surgical stimulation. Iatrogenic complications, namely nerve damage and local anaesthetic toxicity, did not occur. Recovery was smooth and uneventful. The duration (mean ± SD) of the analgesic effect provided by the nerve block was 130 ± 20 minutes. Conclusion and clinical relevanceThe sciatic-femoral nerve block as described in dogs and rabbits can be performed in raptors as well. Further clinical trials with a control groups are required to better investigate the analgesic efficacy and the safety of this technique in raptors.

The changes in running economy during puberty in overweight and normal weight boys

Summary Study aim: running economy (RE) is important indicator of endurance performance. During puberty dynamic changes in body composition and function are observed, as such RE is also expected to change. The aim of the study was to compare the running economy (RE) in overweight and normoweight boys during a running exercise performed with constant velocity, and the assessment of changes in RE during puberty. Material and methods: the RE of the subjects was evaluated twice: at the age of 11–12 and two years later. 18 overweight and 17 normal weight boys performed a graded test and a week later a submaximal run on a mechanical treadmill. During the exercise, physiological variables (oxygen uptake, heart rate, pulmonary ventilation, tidal volume and breathing frequency) were measured. Results: the intensity of work in both tests (%VO2max, %HRmax) was significantly higher in the overweight boys and decreased with age (non significantly) in both groups. The physiological response during the run in the overweight boys was significantly higher compared to normal weight. When the oxygen uptake was expressed as VO2.BM–0.75, the RE was similar in normal weight and overweight boys. During puberty, the inter-group differences in the metabolic cost of work stay at a relatively stable level. Conclusions: the lowered endurance performance in the overweight boys during puberty remains unchanged. The changes in physiological variables during puberty in both groups occurred in a similar way – the body composition did not influence the course of these changes in puberty.

Assessment of Acute Pain Using Physiologic Variables in Non-communicative Patients: Nurses' Perspectives (S748)

•Provide a synopsis of selected literature of physiologic variables (i.e., diaphoresis, blood pressure, heart rate, and respiratory rate) as they relate to the assessment of acute pain in adult patients who cannot self-report.•Discuss acute care nurses' use of specific physiologic variables (i.e., diaphoresis, blood pressure, heart rate, and respiratory rate) to assess pain in patients unable to self-report, including their perceptions of what constitutes significant changes indicative of acute pain. Physiologic variables (PV) believed to indicate acute pain include diaphoresis and changes in blood pressure (BP), heart rate (HR), and respirations. Nurses report using PV to help determine if patients who cannot self-report are experiencing pain, but literature is lacking. To explore how nurses use PV and PV changes to assess pain in patients unable to self-report. Two focus groups were conducted with 13 nurses at an academic medical center to elicit their experiences and opinions using PV and changes in PV to assess acute pain in patients who can't self-report. Open-ended questions and systematic probes were used until saturation was reached. Data were organized and synthesized using content analysis. When nurses noted PV changes, they said they explore and rule out other causes before attributing them to pain. They reported that changes in respiratory rate, pattern, and depth are the first and most easily observed pain-related PV. Changes in systolic BP were more relevant than changes in diastolic BP and HR changes may also be relevant. Diaphoresis was considered a late sign of uncontrolled pain. Behavioral indicators of acute pain in non-communicative patients were deemed more important than physiologic indicators. Nurses recommended using PV to help assess acute pain and pain relief. PV may add important information to the assessment of acute pain in non-communicative patients and may be useful for evaluating pain and pain relief. Although PV changes can be explained by other factors, their complimentary role to behavioral indicators needs systematic exploration.

Change in physiological variables in the last 2 weeks of life: An observational study of hospital in-patients with cancer

Background: Recognising dying remains a difficult clinical skill which has gained increasing importance in the United Kingdom since the Neuberger review. Clinical and research methods exist to aid recognition of dying but do not exhibit the level of accuracy required for such an important decision. Aim: To explore change in key clinical parameters as cancer patients near the end of life. Design: This is a retrospective cohort study of terminally ill patients. Data were collected from hospital case-notes. Case-note data were analysed using multilevel modelling to explore absolute values and rates of change of given variables. Setting/participants: Hospital in-patients who died from solid-tumour malignancies within a 3-month period in 2009 formed the cohort. The setting was an acute hospital trust in the North of England. Results: A total of 15,337 data points from the case-notes of 102 patients were analysed. There was a clinically and statistically significant deterioration in respiratory function and renal function over the last 2 weeks of life. Heart rate and serum sodium also changed but did not vary greatly from normal limits. White cell parameters, haemoglobin and albumin showed evidence for change over longer periods. Conclusion: Results demonstrate statistically and clinically significant change in routinely measured respiratory and renal function variables during the final 2 weeks of life in people dying with cancer. Although useful in acute early warning scores, in a terminally ill patient, relative haemodynamic stability should not be interpreted as reassuring. Further work is needed to understand how these findings apply to the individual or inform other prognostic work.

Mental fatigue does not affect maximal anaerobic exercise performance.

Mental fatigue can negatively impact on submaximal endurance exercise and has been attributed to changes in perceived exertion rather than changes in physiological variables. The impact of mental fatigue on maximal anaerobic performance is, however, unclear. Therefore, the aim of the present study was to induce a state of mental fatigue to examine the effects on performance, physiological and perceptual variables from subsequent tests of power, strength and anaerobic capacity. Twelve participants took part in the single-blind, randomised, crossover design study. Mental fatigue was induced by 90 min of the computer-based Continuous Performance Task AX version. Control treatment consisted of 90 min of watching emotionally neutral documentaries. Participants consequently completed countermovement jump, isometric leg extension and a 3-min all-out cycling tests. Results of repeated measures analysis of variance and paired t tests revealed no difference in any performance or physiological variable. Rating of perceived exertion tended to be greater when mentally fatigued (mental fatigue = 19 ± 1 vs control = 18 ± 1, p = 0.096, [Formula: see text] = .232) and intrinsic motivation reduced (mental fatigue = 11 ± 4 vs control = 13 ± 6, p = 0.063, d = 0.597) in the mental fatigue condition. Near identical responses in performance and physiological parameters between mental fatigue and control conditions suggest that peripheral mechanisms primarily regulate maximal anaerobic exercise. Whereas mental fatigue can negatively impact submaximal endurance exercise, it appears that explosive power, voluntary maximal strength and anaerobic work capacity are unaffected.

S8 Rituximab Therapy For Refractory Myositis Related Interstitial Lung Disease Unresponsive To Conventional Immunosuppression: The Bristol Interstitial Lung Disease Service Experience

Introduction Rituximab is a chimeric monoclonal antibody against CD20 that depletes B-lymphocytes. There is increasing evidence for its use in Scleroderma ILD. 1 Recently it has been reported as rescue therapy in patients with connective tissue disease related severe fibrotic lung disease who have failed conventional immunosuppression. 2 It remains unclear which patients are most likely to benefit from this potent immunosuppressive treatment. We review here the experience of the Bristol Interstitial Lung Disease service in use of Rituximab in a subset of patients with myositis (Anti-synthetase syndrome and Dermatomyositis). Methods We retrospectively reviewed the case notes of 10 patients with severe and progressive ILD despite immunosuppression with Cyclophosphamide and Mycophenolate Mofetil, who had received salvage treatment with Rituximab. Serial pulmonary function tests, 6 min walk distances and HRCT appearances (as assessed by a Thoracic radiologist) were compared in the year before and after Rixtuximab therapy. Changes in physiological variables compared to nadir at treatment were compared with paired-samples T-Test. Results The average age of the patients was 49.8 (range 26.9–72.99), with 7/10 female. 4 patients had dermatomyositis, while 6 had Anti-Synthetase Syndrome (2 Anti-Jo1, 2 Anti-PL12, 1 Anti-PL7, 1 Anti-PM-Scl). There were complete lung function data available for 9 patients and 6MWD data for 6 patients. CT appearances stabilised in all 9 patients with follow-up scans available, with significant improvement in 2 (1 after a second pulse of Rituximab). FVC improved after treatment by an average of 9.2% (p = 0.023, 95% CI 1.67–16.76), with TLCO improving by an average of 6.1% (NS). Figure shows% change in FVC and TLCO leading to and after therapy. 6MWD remained stable. There were no adverse events reported. Summary Our experience adds to the growing evidence to support the use of Rituximab in severe CTD-ILD, and suggests that a subset of patients with myositis may show good therapeutic response. References Daoussis et al . Rheumatology .2010;49;271–80 Keir et al . Respirology 2013;19;353–9

Influence of sex, reproductive status and foetal number on erythrocyte osmotic fragility, haematological and physiologic parameters in goats during the hot-dry season

The current study was aimed at evaluating the effect of heat stress (during the hot-dry period) on some physiological variables, haematology and erythrocyte osmotic fragility (EOF) in bucks, pregnant (single and twin) and lactating Red Sokoto (RS) goats. Forty apparently healthy adult goats were used for the study and were allotted to four groups [bucks (n = 10), pregnant (n = 10) dry (n = 10), and lactating (n = 10) does]. The pregnant goats were further re-grouped according to number of foetuses (single foetus, n = 5 and twins, n = 5). The temperature-humidity index and physiological variables measured were significantly higher in the afternoon compared to morning hours. Pregnant does had higher respiratory and pulse rates than the dry does, but no significant change (P &amp;gt; 0.05) in rectal temperature was observed between groups. On the basis of sex, bucks had lower (P &amp;lt; 0.05) mean corpuscular volume (MCV) than other groups, in addition to having higher (P &amp;lt; 0.01) mean corpuscular haemoglobin (MCH) and total leucocyte counts than dry does. Pregnant does exhibited significantly lower (P &amp;lt; 0.05) packed cell volume, but significantly higher (P &amp;lt; 0.05) MCH and mean corpuscular haemoglobin concentrations (MCHC) than lactating does. Does with a single foetus had significantly lower (P &amp;lt; 0.05) MCV, but higher MCHC than does with twin pregnancies. Using EOF as a biomarker of oxidative stress, erythrocytes of bucks were significantly more resistant to hypotonic haemolysis than those of dry, pregnant and lactating does, with no significant difference in EOF between does of different groups. The erythrocytes of single and twin pregnancies showed similar haemolysis pattern. In conclusion, sex, lactation, and the number of foetuses carried by pregnant does significantly influences physiological and haematological variables in RS goats during the hot-dry season. Also, during heat stress, the changes in physiological variables seem to enhance favourable adaptation by preventing an increase in rectal temperature even in twin pregnancies. &amp;nbsp;

Biodemographic Analyses of Longitudinal Data on Aging, Health, and Longevity: Recent Advances and Future Perspectives.

Biodemography became one of the most innovative and fastest growing areas in demography. This progress is fueled by the growing variability and amount of relevant data available for analyses as well as by methodological developments allowing for addressing new research questions using new approaches that can better utilize the potential of these data. In this review paper, we summarize recent methodological advances in biodemography and their diverse practical applications. Three major topics are covered: (1) computational approaches to reconstruction of age patterns of incidence of geriatric diseases and other characteristics such as recovery rates at the population level using Medicare claims data; (2) methodological advances in genetic and genomic biodemography and applications to research on genetic determinants of longevity and health; and (3) biodemographic models for joint analyses of time-to-event data and longitudinal measurements of biomarkers collected in longitudinal studies on aging. We discuss how such data and methodology can be used in a comprehensive prediction model for joint analyses of incomplete datasets that take into account the wide spectrum of factors affecting health and mortality transitions including genetic factors and hidden mechanisms of aging-related changes in physiological variables in their dynamic connection with health and survival.

The “second wind” in McArdle's disease patients during a second bout of constant work rate submaximal exercise

Patients with McArdle's disease (McA) typically show the "second-wind" phenomenon, a sudden decrease in heart rate (HR) and an improved exercise tolerance occurring after a few minutes of exercise. In the present study, we investigated whether in McA a first bout of exercise determines a second wind during a second bout, separated by the first by a few minutes of recovery. Eight McA (44 ± 4 yr) and a control group of six mitochondrial myopathy patients (51 ± 6 yr) performed two repetitions (CWR1 and CWR2) of 6-min constant work rate exercise (∼50% of peak work rate) separated by 6-min (SHORT) or 18-min (LONG) recovery. Pulmonary O2 uptake (Vo2), HR, cardiac output, rates of perceived exertion, vastus lateralis oxygenation {changes in deoxygenated Hb and myoglobin Mb concentrations, Δ[deoxy(Hb+Mb)], by near-infrared spectroscopy} were determined. In McA, Vo2 (0.86 ± 0.2 vs. 0.95 ± 0.1 l/min), HR (113 ± 10 vs. 150 ± 13 beats/min), cardiac output (11.6 ± 0.6 vs. 15.0 ± 0.8 l/min), and rates of perceived exertion (11 ± 2 vs. 14 ± 3) were lower, whereas Δ[deoxy(Hb+Mb)] was higher (14.7 ± 2.3 vs. -0.1 ± 4.6%) in CWR2-SHORT vs. CWR1; the "overshoot" of Δ[deoxy(Hb+Mb)] and the "slow component" of Vo2 kinetics disappeared in CWR2-SHORT. No differences (vs. CWR1) were observed in McA during CWR2-LONG, or in mitochondrial myopathy patients during both CWR2-SHORT and -LONG. A second-wind phenomenon was observed in McA during the second of two consecutive 6-min constant-work rate submaximal exercises. The second wind was associated with changes of physiological variables, suggesting an enhanced skeletal muscle oxidative metabolism. The second wind was not described after a longer (18-min) recovery period.

Effects of outdoor temperature on changes in physiological variables before and after lunch in healthy women

Previous studies of autonomic nervous system responses before and after eating when controlling patient conditions and room temperature have provided inconsistent results. We hypothesized that several physiological parameters reflecting autonomic activity are affected by outdoor temperature before and after a meal. We measured the following physiological variables before and after a fixed meal in 53 healthy Japanese women: skin temperature, systolic and diastolic blood pressure, salivary amylase, blood glucose, heart rate, and heart rate variability. We assessed satiety before and after lunch using a visual analog scale (100 mm). We recorded outdoor temperature, atmospheric pressure, and relative humidity. Skin temperature rose significantly 1 h after eating (greater in cold weather) (P = 0.008). Cold weather markedly influenced changes in diastolic blood pressure before (P = 0.017) and after lunch (P = 0.013). Fasting salivary amylase activity increased significantly in cold weather but fell significantly after lunch (significantly greater in cold weather) (P = 0.007). Salivary amylase was significantly associated with cold weather, low atmospheric pressure, and low relative humidity 30 min after lunch (P < 0.05). Cold weather significantly influenced heart rate variability (P = 0.001). The decreased low frequency (LF)/high frequency (HF) ratio, increased Δ LF/HF ratio, and increased Δ salivary amylase activity imply that cold outdoor temperature is associated with dominant parasympathetic activity after lunch. Our results clarify the relationship between environmental factors, food intake, and autonomic system and physiological variables, which helps our understanding of homeostasis and metabolism.Electronic supplementary materialThe online version of this article (doi:10.1007/s00484-014-0800-1) contains supplementary material, which is available to authorized users.

Time to Exhaustion at Continuous and Intermittent Maximal Lactate Steady State During Running Exercise

The purpose of this study was to determine and compare the time to exhaustion (TE) and the physiological responses at continuous and intermittent (ratio 5:1) maximal lactate steady state (MLSS) in well-trained runners. Ten athletes (32.7 ± 6.9 y, VO2max 61.7 ± 3.9 mL · kg-1 · min-1) performed an incremental treadmill test, three to five 30-min constant-speed tests to determine the MLSS continuous and intermittent (5 min of running, interspaced by 1 min of passive rest), and 2 randomized TE tests at such intensities. Two-way ANOVA with repeated measures was used to compare the changes in physiological variables during the TE tests and between continuous and intermittent exercise. The intermittent MLSS velocity (MLSSint = 15.26 ± 0.97 km/h) was higher than in the continuous model (MLSScon = 14.53 ± 0.93 km/h), while the TE at MLSScon was longer than MLSSint (68 ± 11 min and 58 ± 15 min, P < .05). Regarding the cardiorespiratory responses, VO2 and respiratory-exchange ratio remained stable during both TE tests while heart rate, ventilation, and rating of perceived exertion presented a significant increase in the last portion of the tests. The results showed a higher tolerance to exercising during MLSScon than during MLSSint in trained runners. Thus, the training volume of an extensive interval session (ratio 5:1) designed at MLSS intensity should take into consideration this higher speed at MLSS and also the lower TE than with continuous exercise.

Aplicación de la prueba de caminata de 6 minutos y escala de borg modificada en sujetos con diversos tipos de cáncer./Aplication of the 6 minute walk test and the modified borg scale in subjects with different types of cancer

Objetivo: Aplicar la PC6M y E.B.M en sujetos con diversos tipos de cáncer en pacientes de la Fundación de Alivio contra el cáncer AVAC, Bucaramanga – Colombia.Materiales y métodos: Se realizó un estudio de corte transversal descriptivo en el periodo de junio a diciembre de 2010Resultados: La muestra estuvo conformada por 40 sujetos la mayoría de sexo femenino 72,5 %, con predominio del cáncer de mama 32,5%, se encontraron cambios estadísticamente significativos en variables fisiológicas al inicio y al final de la prueba (p=0,000), el promedio de metros recorridos en la PC6M 307,7 ±93,9 metros.Conclusión: La diminución de los metros recorridos aporta informacion acerca de la disminucion de la capacidad fisica en los sujetos con cancer. Objective: Was to apply the 6MWT and the MBS on subjects with different types ofcancer in patients Relief Foundation QALY cancer, Bucaramanga - Colombia. Materialsand methods: A cross-sectional descriptive study was made within a period ofJune to December 2010. Results: The sample consisted of 40 subjects most 72.5%female, predominantly breast cancer 32.5%, were found statistically significant changesin physiological variables at the beginning and end of the trial (p = 0.000), theaverage distance walked in PC6M 307.7 ± 93.9 meters. Discussion: The decreaseof the distance walked provide information about the decline of physical capacity insubjects with cancer.

Continuous versus intermittent physiological monitoring for acute stroke

Explanations for the effectiveness of stroke units compared with general wards in reducing mortality, institutionalisation and dependence of people with stroke remain undetermined, and the discussion on the most effective stroke unit model is still up for debate. The intensity of non-invasive mechanical monitoring in many western countries is one of the main issues regarding the different models. This is because of its strong impact on the organisation of the stroke unit in terms of the number of personnel, their expertise, the infrastructure and costs. To assess whether continuous intensive monitoring compared with intermittent monitoring of physiological variables in people with acute stroke can change their prognosis in terms of mortality or disability. We searched the Cochrane Stroke Group Trials Register (November 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 8), MEDLINE (1966 to November 2012), EMBASE (1980 to November 2012), CINAHL (1982 to November 2012) and the British Nursing Index (1985 to November 2012). In an effort to identify further published, unpublished and ongoing trials we searched trials registers (November 2012) and reference lists, handsearched conference proceedings and contacted trial authors. We included all randomised, cluster randomised and quasi-randomised controlled trials comparing continuous monitoring with intermittent monitoring in people within three days of stroke onset. We excluded studies confounded by the delivery of care in different settings (that is studies in which the location of the intervention was not in the same ward in the two arms of the trial). Three review authors independently selected studies for inclusion, assessed methodological quality and extracted data. We sought original data from trialists in two trials and verified the inclusion criteria in another four trials (three presented at conferences and one was from the Chinese Clinical Trial Registry). Where possible, we extracted data on the threshold level of abnormality that triggered intervention for a given physiological variable, the specific intervention given to correct the abnormality and compliance with the allocated therapy. Three studies, involving a total of 354 participants, met our inclusion criteria for the primary outcome. Compared with intermittent monitoring, continuous monitoring significantly reduced death and disability at three months or discharge (odds ratio (OR) 0.27, 95% confidence interval (CI) 0.13 to 0.56) and was associated with a non-significant reduction in deaths from any cause at discharge (OR 0.72, 95% CI 0.28 to 1.85). These significant results depend on one study that has a high risk of bias.Continuous monitoring was associated with a non-significant reduction of dependency (OR 0.79, 95% CI 0.30 to 2.06), death from vascular causes (OR 0.48, 95% CI 0.10 to 2.39), neurological complications (OR 0.81, 95% CI 0.46 to 1.43), length of stay (mean difference (MD) -5.24, 95% CI -10.51 to 0.03) and institutionalisation (OR 0.83, 95% CI 0.04 to 15.72) (secondary outcomes). For the last two outcomes we detected consistent heterogeneity across trials.Cardiac complications (OR 8.65, 95% CI 2.52 to 29.66), fever (OR 2.17, 95% CI 1.22 to 3.84) and hypotension (OR 4.32, 95% CI 1.68 to 14.38) were detected significantly more often in participants who received continuous monitoring (surrogate outcomes).We detected no significant increase in adverse events due to immobility (pneumonia, other infections or deep vein thrombosis) in participants who were continuously monitored compared with those allocated to intermittent monitoring. Continuous monitoring of physiological variables for the first two to three days may improve outcomes and prevent complications. Attention to the changes in physiological variables is a key feature of a stroke unit, and can most likely be aided by continuous monitoring without complications related to immobility or to treatments triggered by the relief of abnormal physiological variables. Well-designed, high-quality studies are needed because many questions remain open and deserve further research. These include when to start continuous monitoring, when to interrupt it, which people should be given priority, and which treatments are most appropriate after the identification of abnormalities in physiological variables.

Computer analysis of non‐invasive measures of cardiovascular variability for deducing autonomic function and for risk stratification

Computer analysis of non‐invasive measures of cardiovascular variability for deducing autonomic function and for risk stratification

Effect of pain on autonomic nervous system indices derived from photoplethysmography in healthy volunteers

Photoplethysmographic pulse wave amplitude (PPGA) and heart rate (HR) can be used to measure cold, nociception-induced autonomic responses, or both. The aim of our study was to correlate the intensity of experimental pain to changes in physiological variables reflecting the autonomic nervous system response to pain. PPGA, HR, and subjective measurements of pain intensity were measured in 29 healthy male volunteers during two heat stimuli (43°C and 48°C) and the cold pressor test (CPT). Surgical pleth index (SPI), autonomic nervous system state (ANSS), and ANSS index (ANSSi) were calculated using PPGA and HR. Pain intensity scores increased on the average by 1.6, 3.5, and 8.1 for the 43°C, 48°C, and CPT stimuli, respectively. The pain intensity scores for all three stimuli groups were significantly different from each other (P<0.001). All three stimuli changed HR, PPGA, SPI, ANSS, and ANSSi values significantly from their respective baseline values (P<0.001 for all). Heat stimuli-induced pain intensity did not correlate with the magnitude of the respective changes in HR, PPGA, SPI, ANSS, and ANSSi. CPT-induced pain intensity correlated with the magnitude of the respective changes in HR, PPGA, SPI, ANSS, and ANSSi. PPGA, ANSSi, ANSS, and SPI differentiated between heat and cold stimuli-induced pain. All three thermal stimuli produced a significant change in photoplethysmograph-derived parameters. All photoplethysmograph-derived parameters appear to be suitable to study autonomic nervous system activation.

The Effect of a Graphical Interpretation of a Statistic Trend Indicator (Trigg's Tracking Variable) on the Detection of Simulated Changes

Anaesthesia involves processing large amounts of information over time. One task of the anaesthetist is to detect substantive changes in physiological variables promptly and reliably. It has been previously demonstrated that a graphical trend display of historical data leads to more rapid detection of such changes. We examined the effect of a graphical indication of the magnitude of Trigg's Tracking Variable, a simple statistically based trend detection algorithm, on the accuracy and latency of the detection of changes in a micro-simulation. Ten anaesthetists each viewed 20 simulations with four variables displayed as the current value with a simple graphical trend display. Values for these variables were generated by a computer model, and updated every second; after a period of stability a change occurred to a new random value at least 10 units from baseline. In 50% of the simulations an indication of the rate of change was given by a five level graphical representation of the value of Trigg's Tracking Variable. Participants were asked to indicate when they thought a change was occurring. Changes were detected 10.9% faster with the trend indicator present (mean 13.1 [SD 3.1] cycles vs 14.6 [SD 3.4] cycles, 95% confidence interval 0.4 to 2.5 cycles, P = 0.013. There was no difference in accuracy of detection (median with trend detection 97% [interquartile range 95 to 100%], without trend detection 100% [98 to 100%]), P = 0.8. We conclude that simple statistical trend detection may speed detection of changes during routine anaesthesia, even when a graphical trend display is present.

Physiological responses to simulated and on-road driving

Driving simulators have become an increasingly popular tool to study and assess drivers. Physiological measurements not only provide an important index of an individual's presence in the virtual environment, but they also permit us to compare simulated and on-road experiences. However, at this point, few studies examining the ecological validity of simulated driving have included physiological variables. In a first study, we embedded three surprising events into a typical simulated road circuit. The first event consisted of a car pulling out suddenly from the shoulder of the road, while the remaining two events consisted of a green traffic light changing to amber as the driver approached the intersection. We noted statistically significant elevations in the mean heart rate (MHR) response to virtual events of about 4 beats per minute (bpm) during the 15 s immediately following the events. In a second study, we directly compared heart rate, oxygen consumption (VO 2), and mean ventilation (MV E) responses to similar simulated and on-road drives. The change in physiological variables from baseline to driving was similar between simulated and on-road conditions, and a very strong correlation between simulated and on-road driving values for MV E (r = 0.90) was observed. MHR and maximum heart rate (HR max) were nonetheless significantly higher during on-road drives. These studies suggest that the level of immersion of a fixed base simulator is great enough to elicit presence, and achieve both relative and absolute validity for certain physiological parameters. Nonetheless, the absolute responses between virtual and real world experiences remain different. For both research and evaluation purposes, it is critical that we better understand the impact of the driver's perceived level of risk or difficulty during simulation on their driving behaviour and physiological responses.