Association between hyperoxemia and mortality in patients treated by eCPR after out-of-hospital cardiac arrest.

OBJECTIVE: Assess whether elevated oxygen partial arterial pressure (PaO2) measured after the initiation of extra-corporeal cardiopulmonary resuscitation (eCPR), is associated with mortality in patients suffering from refractory out-of-hospital cardiac arrest (rOHCA). METHODS: Retrospective cohort study including rOHCA admitted to the ICU. Patients were divided into 3 groups, defined according to the PaO2 measured from arterial blood gas analysis 30 min after the initiation of eCPR. Hyperoxemia was defined as PaO2 ≥ 300 mmHg, hypoxemia as PaO2 ≤ 60 mmHg and normoxemia, as 60 < PaO2 < 300 mmHg. The main outcome was the mortality rate on day 28 after hospital admission. RESULTS: Sixty-six consecutive rOHCA, 77% male, with a mean age of 51 ±â€¯14 years, were admitted to the ICU. rOHCA were mainly due to acute coronary syndrome (67%), hypertrophic cardiomyopathy (8%) and cardiotoxic overdose (8%). Mortality at day 28 reached 61%. In the overall population, the mean PaO2 was 227 ±â€¯124 mmHg. An association between mortality and PaO2 was observed (OR = 1.01 [1.01-1.02]). The AUC for PaO2 after starting eCPR was 0.77 [0.65-0.89]. After adjustment for witnessed arrest, bystander's CPR, location, no-flow, low-flow, lactate and pH, age, and PaCO2, hyperoxemia had an ORa of 1.89 (CI95 [1.74-2.07]). CONCLUSION: We found an association between mortality and hyperoxemia in patients admitted to the ICU for rOHCA requiring eCPR. These data underline the potential toxicity of high dose of oxygen and suggest that controlled oxygen administration for these patients is crucial.

Using deterministic record linkage to link ambulance and emergency department data: is it possible without patient identifiers? A case study from the UK.

INTRODUCTION: Routine linkage of emergency ambulance records with those from the emergency department is uncommon in the UK. Our study, known as the Pre-Hospital Emergency Department Data Linking Project (PHED Data), aimed to link records of all patients conveyed by a single emergency ambulance service to thirteen emergency departments in the UK from 2012-2016. OBJECTIVES: We aimed to examine the feasibility and resource requirements of collecting de-identified emergency department patient record data and, using a deterministic matching algorithm, linking it to ambulance service data. METHODS: We used a learning log to record contacts and activities undertaken by the research team to achieve data linkage. We also conducted semi-structured interviews with information management/governance staff involved in the process. RESULTS: We found that five steps were required for successful data linkage for each hospital trust. The total time taken to achieve linkage was a mean of 65 weeks. A total of 958,057 emergency department records were obtained and, of these, 81% were linked to a corresponding ambulance record. The match rate varied between hospital trusts (50%-94%). Staff expressed strong enthusiasm for data linkage. Barriers to successful linkage were mainly due to inconsistencies between and within acute trusts in the recording of two ambulance event identifiers (CAD and call sign). Further data cleaning was required on emergency department fields before full analysis could be conducted. Ensuring the data was not re-identifiable limited validation of the matching method. CONCLUSION: We conclude that deterministic record linkage based on the combination of two event identifiers (CAD and call sign) is possible. There is an appetite for data linkage in healthcare organisations but it is a slow process. Developments in standardising the recording of emergency department data are likely to improve the quality of the resultant linked dataset. This would further increase its value for providing evidence to support improvements in health care delivery. HIGHLIGHTS: Ambulance records are rarely linked to other datasets; this study looks at the feasibility and resource requirement to use deterministic matching to link ambulance and emergency department data for patients conveyed by ambulance to the emergency department.It is possible to link these data, with an average match rate of 81% across 13 emergency departments and one large ambulance trust.All trusts approached provided match-able data and there was an appetite for data linkage; however, it was a long process taking an average of 65 weeks.We conclude that deterministic matching using no patient identifiers can be used in this setting.

Dimensional metrology of lab-on-a-chip internal structures: a comparison of optical coherence tomography with confocal fluorescence microscopy.

The characterization of internal structures in a polymeric microfluidic device, especially of a final product, will require a different set of optical metrology tools than those traditionally used for microelectronic devices. We demonstrate that optical coherence tomography (OCT) imaging is a promising technique to characterize the internal structures of poly(methyl methacrylate) devices where the subsurface structures often cannot be imaged by conventional wide field optical microscopy. The structural details of channels in the devices were imaged with OCT and analyzed with an in-house written ImageJ macro in an effort to identify the structural details of the channel. The dimensional values obtained with OCT were compared with laser-scanning confocal microscopy images of channels filled with a fluorophore solution. Attempts were also made using confocal reflectance and interferometry microscopy to measure the channel dimensions, but artefacts present in the images precluded quantitative analysis. OCT provided the most accurate estimates for the channel height based on an analysis of optical micrographs obtained after destructively slicing the channel with a microtome. OCT may be a promising technique for the future of three-dimensional metrology of critical internal structures in lab-on-a-chip devices because scans can be performed rapidly and noninvasively prior to their use.

Segmenting time-lapse phase contrast images of adjacent NIH 3T3 cells.

We present a new method for segmenting phase contrast images of NIH 3T3 fibroblast cells that is accurate even when cells are physically in contact with each other. The problem of segmentation, when cells are in contact, poses a challenge to the accurate automation of cell counting, tracking and lineage modelling in cell biology. The segmentation method presented in this paper consists of (1) background reconstruction to obtain noise-free foreground pixels and (2) incorporation of biological insight about dividing and nondividing cells into the segmentation process to achieve reliable separation of foreground pixels defined as pixels associated with individual cells. The segmentation results for a time-lapse image stack were compared against 238 manually segmented images (8219 cells) provided by experts, which we consider as reference data. We chose two metrics to measure the accuracy of segmentation: the 'Adjusted Rand Index' which compares similarities at a pixel level between masks resulting from manual and automated segmentation, and the 'Number of Cells per Field' (NCF) which compares the number of cells identified in the field by manual versus automated analysis. Our results show that the automated segmentation compared to manual segmentation has an average adjusted rand index of 0.96 (1 being a perfect match), with a standard deviation of 0.03, and an average difference of the two numbers of cells per field equal to 5.39% with a standard deviation of 4.6%.

Patients' experiences of care provided by emergency care practitioners and traditional ambulance practitioners: a survey from the London Ambulance Service.

Patients' experiences after receiving care from emergency care practitioners (ECPs) were compared with those after receiving care from traditional ambulance practitioners using a postal questionnaire distributed to 1658 patients in London; 888 responses were received. The responses of patients receiving care from both groups were similar and largely positive. But in two areas ("thoroughness of assessment" and "explaining what would happen next"), the care provided by ECPs was experienced as considerably better. These differences were partly explained by considerably fewer patients from ECPs being conveyed to the emergency department, suggesting that empowering ECPs to explore and explain alternatives to the emergency department improves patient satisfaction.

[Atypical erythema induratum Bazin with tuberculous osteomyelitis]. / Atypisches erythema induratum Bazin bei tuberkulöser osteomyelitis.

Diagnosis of all types of cutaneous tuberculosis is challenging because the clinical picture of these diseases is highly variable. We describe the case of a 79-year old woman with an atypical presentation of Erythema induratum Bazin (EIB) on the chest and left arm in association with a tuberculous osteomyelitis of the left olecranon. Surprisingly, M. tuberculosis grew also from biopsies of the EIB-lesions. This contradicts the conventional view that considers EIB (a tuberculid) to be caused by a hypersensitivity reaction to mycobacteria. The presented case supports the hypothesis that EIB may also be caused by hematogenous or lymphatic spread of viable M. tuberculosis.

Hearing half the message? A re-audit of the care of patients with acute asthma by emergency ambulance crews in London.

PROBLEM: An initial audit of the care provided to emergency asthma patients by the ambulance service was carried out in 1996. Some under-recognition and under-treatment of severe asthma was found as well as a lack of documentation of patient condition on scene. A re-audit was undertaken in 1999. DESIGN: A multidisciplinary advisory group was reconvened. The same method was adopted as for the first audit. Patients included were those administered nebulised salbutamol by crews in the catchment areas of four hospitals and those diagnosed with asthma at the Accident & Emergency (A&E) departments of those hospitals between January and March 1999. SETTING: London Ambulance Service. KEY MEASURES FOR IMPROVEMENT: (1) Accuracy of diagnosis and appropriateness of treatment, and (2) adherence to protocol. STRATEGIES FOR CHANGE: Following the first audit, treatment protocols were widened and brought into line with the British Thoracic Society guidelines for care of acute asthma patients. The results were widely disseminated within the service and training was initiated for all operational staff. EFFECTS OF CHANGE: The number of patients included in the re-audit more than doubled (audit 1: n = 252, audit 2: n = 532). The increase occurred exclusively in those administered nebulised salbutamol by ambulance crews but diagnosed with conditions other than asthma in A&E (audit 1: n = 15, audit 2: n = 161). The proportion of patients diagnosed with asthma in A&E who were administered nebulised salbutamol by their attending crew rose from 58% to 75%. However, 43 asthma patients were not treated; several of these were not recognised as suffering from asthma and others fell within the changed protocols for treatment. Adherence to protocol for administration of salbutamol remained high. Pre-hospital documentation of key observations did not improve. LESSONS LEARNT: Messages from the first audit seem to have been acted upon selectively. Implementing change is complex, and re-audit is necessary to understand the effects of the changes made.

Gaps between policy, protocols and practice: a qualitative study of the views and practice of emergency ambulance staff concerning the care of patients with non-urgent needs.

AIM: To describe emergency ambulance crews' views about (1) how they make decisions on whether to convey patients to hospital; (2) an intervention enabling them to triage patients to non-conveyance; and (3) their experience of using new protocols for undertaking such triage. METHODS: Two focus groups were held at the outset of an evaluation of Treat and Refer (T&R) protocols: one with staff based at an ambulance station who were to implement the new service (intervention station), and the other with staff from a neighbouring station who would be continuing their normal practice during the study (control station). A third session was held with staff from the intervention station following training and 3 months' experience of protocol usage. RESULTS: Before the introduction of the T&R protocols, crews reported experience, intuition, training, time of call during shift, patient preference, and home situation as influencing their decisions concerning conveyance. Crews were positive about changing practice but foresaw difficulties with advising patients who wanted to go to hospital, and with referral to other agencies. Following experience of T&R protocol use, crews felt they had needed more training than had been provided. Some felt their practice and job satisfaction had improved. Problems with referral and with persuading some patients that they did not need to go to hospital were discussed. There was consensus that the initiative should be introduced across the service. CONCLUSIONS: With crews generally positive about this intervention, an opportunity to tackle this difficult area of emergency care now exists. This study has, however, highlighted the complexity of the change in practice and service delivery, and professional and organisational constraints that need to be considered.

Towards primary care for non-serious 999 callers: results of a controlled study of "Treat and Refer" protocols for ambulance crews.

OBJECTIVE: To develop and evaluate "Treat and Refer" protocols for ambulance crews, allowing them to leave patients at the scene with onward referral or self-care advice as appropriate. METHODS: Crew members from one ambulance station were trained to use the treatment protocols. Processes and outcomes of care for patients attended by trained crews were compared with similar patients attended by crews from a neighbouring station. Pre-hospital records were collected for all patients. Records of any emergency department and primary care contacts during the 14 days following the call were collected for non-conveyed patients who were also followed up by postal questionnaire. RESULTS: Twenty three protocols were developed which were expected to cover over 75% of patients left at the scene by the attending crew. There were 251 patients in the intervention arm and 537 in the control arm. The two groups were similar in terms of age, sex and condition category but intervention cases were more likely to have been attended during daytime hours than at night. There was no difference in the proportion of patients left at the scene in the intervention and control arms; the median job cycle time was longer for intervention group patients. Protocols were reported as having been used in 101 patients (40.2%) in the intervention group; 17 of the protocols were recorded as having been used at least once during the study. Clinical documentation was generally higher in the intervention group, although a similar proportion of patients in both groups had no clinical assessments recorded. 288 patients were left at the scene (93 in the intervention group, 195 in the control group). After excluding those who refused to travel, there were three non-conveyed patients in each group who were admitted to hospital within 14 days of the call who were judged to have been left at home inappropriately. A higher proportion of patients in the intervention arm reported satisfaction with the service and advice provided. CONCLUSIONS: "Treat and Refer" protocols did not increase the number of patients left at home but were used by crews and were acceptable to patients. The protocols increased job cycle time and some safety issues were identified. Their introduction is complex, and the extent to which the content of the protocols, decision support and training can be refined needs further study.

On-scene alternatives for emergency ambulance crews attending patients who do not need to travel to the accident and emergency department: a review of the literature.

With rising demand and recognition of the variety of cases attended by emergency ambulance crews, services have been considering alternative ways of providing non-urgent care. This paper describes and appraises the research literature concerning on-scene alternatives to conveyance to an emergency department, focusing on the: (1) profile and outcomes of patients attended but not conveyed by emergency crews; (2) triage ability of crews; (3) effectiveness and safety of protocols that allow crews to convey patients to alternative receiving units or to self care. The literature search was conducted through standard medical databases, supplemented with manual searches. Very few "live" studies were identified, and fewer still that included a control group. Findings indicated a complex area, with the introduction of protocols allowing crews to leave patients at scene carrying clinical risk. Robust research evidence concerning alternatives to current emergency care models is needed urgently to inform service and practice development.

Appropriateness of intravenous cannulation by paramedics: a London study.

INTRODUCTION: The number of patients undergoing intravenous (IV) cannulation by paramedics has increased dramatically over recent years in the UK. Treatment protocols for cannulation in the field are loosely defined. Variation in practice may lead to patients' receiving differential treatment according to customary practice, rather than according to their clinical conditions. OBJECTIVES: To explore variations in practice and assess level of appropriatenesss of IV cannulation by London Ambulance Service (LAS) paramedics; to revise treatment protocols and work toward clinical guidelines, if indicated by study findings. METHODS: Skill usage data were analyzed for all LAS paramedics for 1995-96. All patients who were IV-cannulated and transported to three hospitals by LAS during March 1996 were identified. A panel of accident and emergency (A&E) and prehospital specialists judged each case for appropriateness. RESULTS: Variation during the year was wide, with a range of 1 to 221 (mean 47) patients cannulated per paramedic, although the majority showed some consistency in frequency of skill usage. A sample of 183 cases was reviewed. The majority judged 149 (81.4%) to be appropriate, although there was considerable disagreement between reviewers (kappa = 0.43, p < 0.001). Data suggested that those paramedics who cannulate more frequently cannulated less appropriately during the study period (lowest 30%: 73.9% appropriate; highest 30%: 45.8% appropriate, p = 0.05). CONCLUSION: Despite wide variation between paramedics, the panel judged overall appropriateness of cannulation to be high. The audit advisory group judged that new clinical guidelines might not achieve an improvement in practice and were not supported by study findings. It was recommended that variations be addressed through individual practice review.

Out-of-hospital intravenous cannulation: the perspective of patients treated by London Ambulance Service paramedics.

OBJECTIVES: Previous research has highlighted concern about infection rates in field-placed intravenous (IV) cannulae. In a study of IV placement by London Ambulance Service (LAS) paramedics, 17% of placements were judged to be inappropriate. Large variations in rates of IV placement between LAS paramedics were found. The authors' hypothesis was that placement of an IV carries disadvantages-pain, discomfort, distress, and infection-which may be unacceptable to patients. METHODS: This was a survey of all patients having an IV placed by LAS paramedics and transported to one of three London emergency departments (EDs) over a three-week period in December 1996. Patients were excluded if they had a self-inflicted injury/illness, were less than 14 years old, had no known address, or were visitors to the UK, or if their family doctor suggested it was not appropriate to contact the patient. Pain, discomfort, and distress; infection; satisfaction; understanding of the reason for cannulation; and out-of-hospital cannula use were all ascertained and analyzed with chi-square analysis. RESULTS: Thirty-nine percent of the respondents experienced some discomfort, 39% some pain, and 17% some distress. No patient reported an infection. Distress was more likely to be reported if there was no understanding of why the IV cannula was placed (chi2 [1] 6.1; p < 0.05). Further unstructured information revealed satisfaction with the IV cannulation and with general care. CONCLUSIONS: Despite the disadvantages of IV placement being reported by some respondents, overall levels of satisfaction were high, suggesting that these disadvantages were not unacceptable to patients. However, in the context of the 24,000 patients cannulated each year by LAS paramedics, "costs" to the patient are considerable.

Comparison of outer-membrane fractions of Serpulina (Treponema) hyodysenteriae.

Sarkosyl-insoluble fractions (outer-membrane proteins) and endoflagella (EF) fractions of Serpulina hyodysenteriae serotypes 1-7 were examined for protein differences using SDS-PAGE. Both the outer-membrane proteins (OMP) and endoflagella were also examined for antigenicity using porcine sera from acutely infected and convalescent swine. Seven major staining proteins were resolved in outer-membrane enriched fractions ranging in molecular weight between 42 and 32 kDa. A comparison of purified EF to OMP from serotype 1 and 2 isolates of Serpulina hyodysenteriae demonstrated that six of the seven OMP were actually EF. Sera from swine with acute swine dysentery identified only a portion of the proteins from both preparations. In contrast, immune sera from convalescent swine identified all the proteins in the OMP and EF preparations as well as an additional 16 kDa carbohydrate antigen.

Lipooligosaccharides from Treponema hyodysenteriae and Treponema innocens.

Lipooligosaccharides from Treponema hyodysenteriae serotypes 1 through 7, attenuated T. hyodysenteriae serotypes 1 and 2, and five strains of T. innocens were extracted with hot phenol water. The extracts were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis separation and analyzed by lipopolysaccharide selective silver staining and Western blot (immunoblot) immunodetection. Silver staining revealed the presence of two bands that ranged between 18,000 and 24,000 daltons and that were serotype specific for T. hyodysenteriae. Attenuation of pathogenic strains resulted in the loss of the higher-molecular-weight band. Four of five T. innocens strains also lacked this particular band. T. innocens 421 had six bands between 17,000 and 26,900 daltons. Western blots with hyperimmune rabbit sera and convalescent-phase swine sera revealed antigenic variation among serotypes of T. hyodysenteriae and attenuated serotypes of T. hyodysenteriae. Convalescent-phase swine sera failed to recognize lipopolysaccharides from T. innocens. Differences in results obtained by lipopolysaccharide selective silver staining versus immunoblotting of the lipopolysaccharide preparations probably indicate that these two methods identify separate characteristics of the same molecule.