Neural responses to a modified Stroop paradigm in patients with complex chronic musculoskeletal pain compared to matched controls: an experimental functional magnetic resonance imaging study.

BACKGROUND: Chronic musculoskeletal pain (CMSKP) is attentionally demanding, complex and multi-factorial; neuroimaging research in the population seen in pain clinics is sparse. A better understanding of the neural activity underlying attentional processes to pain related information compared to healthy controls may help inform diagnosis and management in the future. METHODS: Blood oxygenation level dependent functional magnetic resonance imaging (BOLD fMRI) compared brain responses in patients with CMSKP (n = 15) and healthy controls (n = 14) while completing a modified Stroop task using pain-related, positive-emotional, and neutral control words. RESULTS: Response times in the Stroop task were no different for CMSKP patients compared with controls, but patients were less accurate in their responses to all word types. BOLD fMRI responses during presentation of pain-related words suggested increases in neural activation in patients compared to controls in regions previously reported as being involved in pain perception and emotion: the anterior cingulate cortex, insula and primary and secondary somatosensory cortex. No fMRI differences were seen between groups in response to positive or control words. CONCLUSIONS: Using this modified Stroop tasks, specific differences were identified in brain activity between CMSKP patients and controls in response to pain-related information using fMRI. This provided evidence of differences in the way that pain-related information is processed in those with chronic complex musculoskeletal pain that were not detectable using the behavioural measures of speed and accuracy. The study may be helpful in gaining new insights into the impact of attention in those living with chronic pain.

Cardiff cardiac ablation patient-reported outcome measure (C-CAP): validation of a new questionnaire set for patients undergoing catheter ablation for cardiac arrhythmias in the UK.

PURPOSE: To formally test and validate a patient-reported outcome measure (PROM) for patients with cardiac arrhythmias undergoing catheter ablation procedures in the UK [Cardiff Cardiac Ablation PROM (C-CAP)]. METHODS: A multicentre, prospective, observational cohort study with consecutive patient enrolment from three UK sites was conducted. Patients were sent C-CAP questionnaires before and after an ablation procedure. Pre-ablation C-CAP1 (17 items) comprised four domains: patient expectations; condition and symptoms; restricted activity and healthcare visits; medication and general health. Post-ablation C-CAP2 (19 items) comprised five domains including change in symptoms and procedural complications. Both questionnaires also included the generic EQ-5D-5L tool (EuroQol). Reliability, validity, and responsiveness measures were calculated. RESULTS: A total of 517 valid pre-ablation and 434 post-ablation responses were received; questionnaires showed good feasibility and item acceptability. Internal consistency was good (Cronbach's alpha >0.7) and test-retest reliability was acceptable for all scales. C-CAP scales showed high responsiveness (effect size >0.8). Patients improved significantly (p < 0.001) following ablation across all disease-specific and global scales. Minimal clinically important difference was calculated. Improvement beyond the smallest detectable change of 9 points (symptom severity scale), 3 points (frequency and duration of symptoms scale), and 8 points (impact on life scale) indicates an important change. Amendments to the C-CAP questionnaires were identified through the validation process and made to produce the final tools. CONCLUSIONS: The final C-CAP questionnaires are valid, reliable, and responsive tools for measuring symptom change, impact, and expectations in patients undergoing ablation for cardiac arrhythmias. C-CAP questionnaires provide a tool with disease-specific and generic domains to explore how cardiac ablation procedures in the UK impact upon patients' lives.

A Functional Magnetic Resonance Imaging Study to Investigate the Utility of a Picture Imagination Task in Investigating Neural Responses in Patients with Chronic Musculoskeletal Pain to Daily Physical Activity Photographs.

Pain-related anxiety and fear are associated with increased difficulties in attention, increased awareness of pain, impaired disengagement from pain, and can moderate the effects of attentional coping attempts. Accurately assessing the direct impact of pain-related anxiety and fear on pain behavior has proved difficult. Studies have demonstrated no or limited influence of pain-related fear and anxiety on behavior but this may be due to inherent problems with the scales used. Neuroimaging has improved the understanding of neural processes underlying the factors that influence pain perception. This study aimed to establish if a Picture and Imagination Task (PIT), largely developed from the Photographs of Daily Activity (PHODA) assessment tool, could help explore how people living with chronic pain process information about daily activities. Blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI) was used to compare brain responses in patients with chronic musculoskeletal pain (CMSKP) (n = 15) and healthy controls (n = 15). Subjects were asked to imagine how they would feel mentally and physically if asked to perform daily activities illustrated in PIT. The results found that a number of regions involved in pain processing saw increased BOLD activation in patients compared with controls when undertaking the task and included the insula, anterior cingulate cortex, thalamus and inferior and superior parietal cortices. Similarly, increased BOLD responses in patients compared to controls in the frontal pole, paracingulate and the supplementary motor cortex may be suggestive of a memory component to the responses The amygdala, orbitofrontal cortex, substantia nigra/ventral tegmentum, putamen, thalamus, pallidum, inferior parietal (supramarginal and angular gyrus) and cingulate cortex were also seen to have greater differences in BOLD signal changes in patients compared with controls and many of these regions are also associated with general phobic responses. Therefore, we suggest that PIT is a useful task to explore pain- and movement-related anxiety and fear in fMRI studies. Regions in the Default Mode Network remained active or were less deactivated during the PIT task in patients with CMSKP compared to healthy controls supporting the contention that the DMN is abnormal in patients with CMSKP.

Volatile fluorinated nanoemulsions: a chemical route to controlled delivery of inhalation anesthesia.

Novel dispersions of the volatile inhalation anesthetic sevoflurane have been formulated that can provide controlled, sustainable release of anesthetic over clinically useful timescales. The emulsions can be simply formed with manual shaking, reproducibly yielding droplets of the order of 250 nm diameter, i.e. within the nanoemulsion range. Using a custom flow-rig, release of anesthetic gas from the emulsion has been evaluated, and clinically useful levels achieved through appropriate stirring of the formulation. Stirring can also be used to temporarily increase or decrease the amount of anesthetic released. Once consideration of the unusual nature of the fluorinated systems (phase separation by sedimentation rather than creaming), and the highly perturbed environment of their evaluation (under stirring and flow of gas), the observed behavior regarding sevoflurane evaporation can be reasonably well explained by existing theoretical models. Links between anesthetic release and emulsion structure have been defined, providing the basis for future development.

A survey of anaesthetic practice in predicting difficult intubation in UK and Europe.

CONTEXT: Unexpected difficulty in tracheal intubation is an intermittent and often terrifying problem for all practising anaesthetists. There are many preoperative assessment tests to predict a difficult laryngeal view or a difficult intubation, but we found no published evidence of how frequently these predictive tests are used or how useful they are perceived to be by anaesthetists. OBJECTIVE: We decided to ask UK and non-UK anaesthetists attending the Annual Scientific Meeting of the European Society of Anaesthesiology about their practice in predicting difficult intubation. DESIGN: The study was conceived as a survey. SETTING: The airway tests were compiled into a questionnaire, hand distributed among anaesthetists at Euroanaesthesia - the European group (after excluding UK attendees) - and posted to randomly selected anaesthetists in the UK - the UK group. PARTICIPANTS: Overall, 888 of 1230 (72%) questionnaires were completed. The response rate from the UK group of anaesthetists was 69% (481 of 700) and from the European group was 77% (407 of 530). RESULTS: On a scale 1 (never) to 5 (always), the mean score for frequency of use was similar for both groups of anaesthetists and ranged from about 4 for mouth opening to about 1 for Nodding Donkey. The mean score for usefulness (1 = useless, 5 = extremely useful) ranged from about 3.7 to 2 for the same two tests. The UK group found most tests slightly less useful than did the European group. With regard to the frequency of assessing the airway, 9% of the European group, but 16% of the UK group, failed always (score 5) or regularly (score 4) to assess the airway before general anaesthesia. Furthermore, 21 and 36% of the UK and European groups, respectively, failed to do so before regional anaesthesia. CONCLUSION: These results are a cause for concern with regard to both airway management training and patient safety.

Extubation after anaesthesia: a randomised comparison of three techniques.

The mode of ventilation used during awake extubation has not previously been studied. We conducted a randomised controlled trial comparing spontaneous respiration, intermittent positive pressure ventilation, and pressure support ventilation (each n = 13) for incidence and severity of peri-extubation complications following routine elective surgery. We found the severity of peri-extubation cough was significantly affected by mode of ventilation used at extubation (p = 0.049), with lowest severity grades for those in the pressure support ventilation group. The mean arterial pressure at extubation was lowest in the intermittent positive pressure ventilation group (p = 0.007). Other peri-extubation complications and time to extubation following cessation of anaesthesia were not significantly different across the three groups. We suggest that the use of pressure support ventilation for awake extubation may offer an advantage over spontaneous and intermittent positive pressure ventilation extubation strategies.

Infection prevention during anaesthesia ventilation by the use of breathing system filters (BSF): Joint recommendation by German Society of Hospital Hygiene (DGKH) and German Society for Anaesthesiology and Intensive Care (DGAI).

An interdisciplinary working group from the German Society of Hospital Hygiene (DGKH) and the German Society for Anaesthesiology and Intensive Care (DGAI) worked out the following recommendations for infection prevention during anaesthesia by using breathing system filters (BSF). The BSF shall be changed after each patient. The filter retention efficiency for airborne particles is recommended to be >99% (II). The retention performance of BSF for liquids is recommended to be at pressures of at least 60 hPa (=60 mbar) or 20 hPa above the selected maximum ventilation pressure in the anaesthetic system. The anaesthesia breathing system may be used for a period of up to 7 days provided that the functional requirements of the system remain unchanged and the manufacturer states this in the instructions for use.THE BREATHING SYSTEM AND THE MANUAL VENTILATION BAG ARE CHANGED IMMEDIATELY AFTER THE RESPECTIVE ANAESTHESIA IF THE FOLLOWING SITUATION HAS OCCURRED OR IT IS SUSPECTED TO HAVE OCCURRED: Notifiable infectious disease involving the risk of transmission via the breathing system and the manual bag, e.g. tuberculosis, acute viral hepatitis, measles, influenza virus, infection and/or colonisation with a multi-resistant pathogen or upper or lower respiratory tract infections. In case of visible contamination e.g. by blood or in case of defect, it is required that the BSF and also the anaesthesia breathing system is changed and the breathing gas conducting parts of the anaesthesia ventilator are hygienically reprocessed.Observing of the appropriate hand disinfection is very important. All surfaces of the anaesthesia equipment exposed to hand contact must be disinfected after each case.

Fluid flow through intravenous cannulae in a clinical model.

BACKGROUND: Predicting flow through an IV cannula is useful to clinicians if changes in flow are required and to guide selection of cannula. We sought the usefulness of manufacturers' quoted flows in predicting actual flow and to characterize that flow. METHODS: We built a vein model and inserted cannulae between 14 and 20-gauge. In the first experiment, we compared the manufacturer's quoted flows using deionized water, Hartmann's solution and Gelofusine. In the second experiment, we varied the pressure feeding the cannula and measured the resulting flow. RESULTS: Flow through a cannula is not a simple ratio of the manufacturers' quoted flow rate, even controlling for fluid type and feeding pressure. Flow is neither fully laminar, nor fully turbulent in the range of rates we have measured and in the International Organization for Standardization test. The Reynolds number is often below 2000. CONCLUSIONS: Flow through cannulae is not laminar at the upper range of clinically used flows, therefore Poiseuille's law is not useful in predicting flow and the effect of changing radius is less than commonly believed. The quoted maximum flows are also not useful. There are many conditions for laminar flow apart from Reynolds number. Further work would determine useful predictors of flow.

Preventing the transmission of pathogenic microbes during anesthesia.

During anesthesia, a breathing system may be used for more than one patient. Any microbes expelled by one patient, whether gasborne in the form of droplets or liquidborne in sputum, should be prevented from entering the breathing system. Breathing system filters are intended to reduce the risk of cross infection during anesthesia and intensive care from these routes. The Medicines and Healthcare products Regulatory Agency published a report in 2004 that included data on the gasborne filtration performance of 104 different filters available on the UK market. A wide range in filtration performance was found. Filters intended for use with pediatric patients do not appear to offer the same level of protection as those intended for use with adult patients, despite the lower flow used to challenge these filters. Recent government initiatives to reduce the prevalence of tuberculosis and hepatitis C in England have again focused interest on the ability of filters to reduce the risk of cross infection from these particular microbes arising from patients who may not be aware that they are harboring the disease. Currently, there are no requirements for the level of filtration that breathing system filters have to provide, either in standards or from professional bodies.

Assessing breathing-system filters.

An assessment of 104 different breathing-system filters has been published by the United Kingdom's Medicines and Healthcare Products Regulatory Agency. Filtration performance was measured by determining the penetration of sodium chloride particles. Wide variations in performance were found. This rapid, easy assessment technique could be used to test each filter during manufacture.