Resuscitation feedback and targeted education improves quality of pre-hospital resuscitation in Scotland.

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality and serious neurological morbidity in Europe. Recent studies have demonstrated the adverse physiological consequences of poor resuscitation technique and have shown that quality of cardiopulmonary resuscitation (CPR) is a critical determinant of outcome from OHCA. Telemetry of the defibrillator transthoracic impedance (TTI) trace can objectively measure quality of pre-hospital resuscitation. This study aims to analyse the impact of targeted resuscitation feedback and training on quality of pre-hospital resuscitation. METHODS: Prospective, single centre, cohort study over 13 months (1st December 2009-31st December 2010). Baseline pre-hospital resuscitation data was gathered over a 3-month period. Modems (n=40) were fitted to defibrillators on ambulance vehicles. Following a resuscitation attempt, the event was sent via telemetry and the TTI trace analysed. Outcome measures were time spent performing chest compressions, compression rate, the interval required to deliver a defibrillator shock and use of automatic or manual cardiac rhythm analysis. Targeted resuscitation classes were introduced and all ambulance crews received feedback following a resuscitation attempt. Pre-hospital resuscitation quality pre and post intervention were compared. RESULTS: 111 resuscitation traces were analysed. Mean hands-on-chest time improved significantly following feedback and targeted resuscitation training (73.0% vs 79.3%, p=0.007). There was no significant change in compression rate during the study period. There was a significant reduction in median time-to-shock interval from 20.25s (IQR 15.50-25.50s) to 13.45 s (IQR 2.25-22.00 s) (p=0.006). Automatic rhythm recognition fell from 50% to 28.6% (p=0.03) following intervention. CONCLUSION: Telemetry and analysis of the TTI trace following OHCA allows objective evaluation of the quality of pre-hospital resuscitation. Targeted resuscitation training and ambulance feedback improves the quality of pre-hospital resuscitation. Further studies are required to establish possible survival benefit from this technique.

Resuscitation quality assurance for out-of-hospital cardiac arrest--setting-up an ambulance defibrillator telemetry network.

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) is a leading cause of pre-hospital mortality. Chest compressions performed during cardiopulmonary resuscitation aim to provide adequate perfusion to the vital organs during cardiac arrest. Poor resuscitation technique and the quality of pre-hospital CPR influences outcome from OHCA. Transthoracic impedance (TTI) measurement is a useful tool in the assessment of the quality of pre-hospital resuscitation by ambulance crews but TTI telemetry has not yet been performed in the United Kingdom. We describe a pilot study to implement a data network to collect defibrillator TTI data via telemetry from ambulances. METHODS: Prospective, observational pilot study over a 5-month period. Modems were fitted to 40 defibrillators on ambulances based in Edinburgh. TTI data was sent to a receiving computer after resuscitation attempts for OHCA. RESULTS: 58 TTI traces were transmitted during the pilot period. Compliance with the telemetry system was high. The mean ratio of chest compressions was 73% (95% CI 69-77%), the mean chest compression rate was 128 (95% CI 122-134). The mean time interval from chest compression interruption to shock delivery was 27 s (95% CI 22-32 s). CONCLUSION: Trans-thoracic impedance analysis is an effective means of recording important measures of resuscitation quality including the hands-on-the-chest time, compression rate and defibrillation interval time. TTI data transmission via telemetry is straightforward, efficient and allows resuscitation data to be captured and analysed from a large geographical area. Further research is warranted on the impact of post-resuscitation reporting on the quality of resuscitation delivered by ambulance crews.

Bystander CPR in south east Scotland increases over 16 years.

BACKGROUND: Out-of-hospital cardiac arrest (OHCA) remains a leading cause of mortality and serious neurological disability across Europe. Without immediate bystander cardiopulmonary resuscitation (CPR), chances of survival are minimal. Despite community initiatives to increase the number of trained CPR providers, the effectiveness of these measures remains unknown and the proportion of OHCA patients receiving bystander CPR in the United Kingdom yet to be established. We sought to identify the change in the rate of bystander CPR in south east Scotland over a 16-year period. METHODS: Retrospective cohort study of all adult non-traumatic OHCA in south east Scotland from 1 January 1992 to 31 December 2007 using the Heartstart Scotland database. RESULTS: 7928 OHCA were included. The proportion of patients receiving bystander CPR increased from 34% in 1992 to 52% in 2007 (p for trend <0.0001). The rate of CPR from bystanders, spouses and from relatives increased significantly over the study period. Patients arresting at home received significantly less bystander CPR than those arresting away from home (39% vs 52%, p<0.0001) regardless of age or sex. CONCLUSION: There has been a significant increase in bystander CPR in south east Scotland during the 16-year period. Bystander CPR is associated with an increased rate of survival and targeted CPR training for relatives of patients at risk of sudden cardiac death may be beneficial.

Therapeutic hypothermia in the emergency department following out-of-hospital cardiac arrest.

Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality and severe neurological disability. Recent literature suggests that mild therapeutic hypothermia (MTH) can improve survival and neurological outcome in some groups of comatose patients after cardiac arrest but uncertainty exists over the best way to implement this treatment. This review examines the evidence for the efficacy and mode of implementation of MTH after OHCA, particularly in the Emergency Department setting. A literature search was performed and all systematic reviews; human and animal randomised and non-randomised trials were screened for inclusion. Specific emphasis was placed on MTH being commenced in the prehospital and Emergency Department setting. Outcome measures were: time to reach target temperature, in-hospital mortality, neurological outcome at hospital discharge and complications of therapeutic hypothermia. Two systematic reviews found that MTH improved outcome after OHCA. Five human randomised controlled trials were identified. Two trials commenced cooling prehospital. One showed a favourable outcome but the other failed to show survival benefit. The other three trials only commenced cooling after the patient arrived in hospital and all showed improved survival for patients treated with MTH after OHCA. Evidence from animal and non-randomised studies suggests cooling should be commenced as early as possible after return of spontaneous circulation. Cold intravenous fluid was reported as a safe, effective means of cooling in the emergency setting. MTH improves patient outcome after OHCA. There is some evidence to suggest cooling should be commenced early. Cold intravenous crystalloid infusion may be the preferred cooling method in the Emergency Department.

Esophageal temperature after out-of-hospital cardiac arrest: an observational study.

INTRODUCTION: Out-of-hospital cardiac arrest (OHCA) is a significant cause of death and severe neurological disability. The only post-return of spontaneous circulation (ROSC) therapy shown to increase survival is mild therapeutic hypothermia (MTH). The relationship between esophageal temperature post OHCA and outcome is still poorly defined. METHODS: Prospective observational study of all OHCA patients admitted to a single centre for a 14-month period (1/08/2008 to 31/09/2009). Esophageal temperature was measured in the Emergency Department and Intensive Care Unit (ICU). Selected patients had pre-hospital temperature monitoring. Time taken to reach target temperature after ROSC was recorded, together with time to admission to the Emergency Department and ICU. RESULTS: 164 OHCA patients were included in the study. 105 (64.0%) were pronounced dead in the Emergency Department. 59 (36.0%) were admitted to ICU for cooling; 40 (24.4%) died in ICU and 19 (11.6%) survived to hospital discharge. Patients who achieved ROSC and had esophageal temperature measured pre-hospital (n=29) had a mean pre-hospital temperature of 33.9 degrees C (95% CI 33.2-34.5). All patients arriving in the ED post OHCA had a relatively low esophageal temperature (34.3 degrees C, 95% CI 34.1-34.6). Patients surviving to hospital discharge were warmer on admission to ICU than patients who died in hospital (35.7 degrees C vs 34.3 degrees C, p<0.05). Patients surviving to hospital discharge also took longer to reach T(targ) than non-survivors (2h 48min vs 1h 32min, p<0.05). CONCLUSIONS: Following OHCA all patients have esophageal temperatures below normal in the pre-hospital phase and on arrival in the Emergency Department. Patients who achieve ROSC following OHCA and survive to hospital discharge are warmer on arrival in ICU and take longer to reach target MTH temperatures compared to patients who die in hospital. The mechanisms of action underlying esophageal temperature and survival from OHCA remain unclear and further research is warranted to clarify this relationship.

Shock outcome prediction before and after CPR: a comparative study of manual and automated active compression-decompression CPR.

We report on a study designed to compare the relative efficacy of manual CPR (M-CPR) and automated mechanical CPR (ACD-CPR) provided by an active compression-decompression (ACD) device. The ECG signals of out-of-hospital cardiac arrest patients of cardiac aetiology were analysed just prior to, and immediately after, cardiopulmonary resuscitation (CPR) to assess the likelihood of successful defibrillation at these time points. The cardioversion outcome prediction (COP) measure previously developed by our group was used to quantify the probability of return of spontaneous circulation (ROSC) after counter-shock and was used as a measure of the efficacy of CPR. An initial validation study using COP to predict shock outcome from the patient data set resulted in a performance of 60% specificity achieved at 100% sensitivity on a blind test of the data. This is comparable with previous studies and provided confidence in the robustness of the technique across hardware platforms. Significantly, the COP marker also displayed an ability to stratify according to outcomes: asystole, ventricular fibrillation (VF), pulseless electrical activity (PEA), normal sinus rhythm (NSR). We then used the validated COP marker to analyse the ECG data record just prior to and immediately after the chest compression segments. This was initially performed for 87 CPR segments where VF was both the pre- and post-CPR waveform. An increase in the mean COP values was found for both CPR types. A signed rank sum test found the increase due to manual CPR not to be significant (p>0.05) whereas the automated CPR was found to be significant (p<0.05). This increase was larger for the automated CPR (1.26, p=0.024) than for the manual CPR (0.99, p=0.124). These results indicate that the application of CPR does indeed provide beneficial preparation of the heart prior to defibrillation therapy whether manual or automated CPR is applied. The COP marker shows promise as a definitive, quantitative determinant of the immediate positive effect of both types of CPR regardless of the details of use. In work of a more exploratory nature we then used the validated COP marker to analyse the ECG pre- and post-CPR for all rhythm types (212 traces). We show a significant increase in the COP measure (p<0.001 in both cases) as indicated by a shift in the median COP marker distribution values. This increase was more pronounced for automated ACD-CPR than for manual CPR. However, a detailed statistical analysis carried out between the groups adjusted for pre-CPR value showed no significant difference between the two methods of CPR (p=0.20). Similarly, adjusting for length of CPR showed no significant difference between the groups. Secondary, subgroup analysis of the ECG according to the length of time for which CPR was performed showed that both types of CPR led to an increase in the likelihood of successful defibrillation after increasing durations of CPR, however results were less reliable after longer periods of continuous CPR.

Practical issues in the evaluation of methods for the prediction of shock outcome success in out-of-hospital cardiac arrest patients.

There is a need for robust, effective predictors of the outcome from shock for out-of-hospital cardiac arrest patients. Such technology would enable the emergency responder to provide a therapy tailored to the patient's needs. Here we report our most recent findings while dwelling intentionally on the rationale behind the decisions taken during system development. Specifically, we illustrate the need for sensible data selection, fully cross-validated results and the care necessary when evaluating system performance. We analyze 878 pre-shock ECG traces, all of at least 10 s duration from 110 patients with cardiac arrest of cardiac aetiology. The continuous wavelet transform was applied to preshock segments of ECG trace. Time-frequency markers are extracted from the transform and a linear threshold derived from a training set to provide high sensitivity prediction of successful defibrillation. These systems are then evaluated on a withheld test set. All experiments are cross-validated. When compared to popular Fourier-based techniques our wavelet transform method, COP (Cardioversion Outcome Predictor), provides a 10-20% improvement in performance with values of 66 +/- 4 specificity at 95 +/- 4 sensitivity, 61 +/- 4 specificity at 97 +/- 2 sensitivity and 56 +/- 1 specificity at 98 +/- 2 sensitivity achieved for datasets limited to 3, 6, and 9 shocks per patient, respectively. Thus, the assessment of the wavelet marker was associated with a high specificity value at or above 95% sensitivity in comparison to previously reported methods. Therefore, COP could provide an optimal index for the identification of patients for whom shocking would be futile, and for whom an alternative therapy could be considered.

A randomised, controlled trial comparing a tissue adhesive (2-octylcyanoacrylate) with adhesive strips (Steristrips) for paediatric laceration repair.

OBJECTIVE: To compare the tissue adhesive 2-octylcyanoacrylate (Dermabond) with adhesive strips, Steristrips in paediatric laceration repair. METHOD: Children with suitable lacerations were randomly allocated for wound closure with either a tissue adhesive or adhesive strips. Thirty children were treated in each group. Linear Visual Analogue Scores were used to judge parents' and nurses' opinions of the application of each treatment. A similar scoring system was used to judge the cosmetic outcome as viewed by parents and a plastic surgeon. Complications and trial failures were noted. RESULTS: Complete data were available for 44 of the children. Parents viewed the treatments as equally acceptable. In contrast those performing the procedure judged the tissue adhesive more difficult to apply. Scores of cosmetic outcome by both parents and the plastic surgeon showed no significant difference in the treatment method used. There were four children in the tissue adhesive group and one from the adhesive strip group in whom the wounds were unable to be closed. CONCLUSION: Both tissue adhesives and adhesive strips are excellent "no needle" alternatives for the closure of suitable paediatric lacerations. This study suggests that the techniques are similar in efficacy, parental acceptability, and cosmetic outcome. The choice as to which is used may come down to economics and operator preference.

A new system for digital image acquisition, storage and presentation in an accident and emergency department.

OBJECTIVES: To develop a computer based storage system for clinical images-radiographs, photographs, ECGs, text-for use in teaching, training, reference and research within an accident and emergency (A&E) department. Exploration of methods to access and utilise the data stored in the archive. METHODS: Implementation of a digital image archive using flatbed scanner and digital camera as capture devices. A sophisticated coding system based on ICD 10. Storage via an "intelligent" custom interface. RESULTS: A practical solution to the problems of clinical image storage for teaching purposes. CONCLUSIONS: We have successfully developed a digital image capture and storage system, which provides an excellent teaching facility for a busy A&E department. We have revolutionised the practice of the "hand-over meeting".

A novel wavelet transform based analysis reveals hidden structure in ventricular fibrillation.

We report a new method of interrogating the surface ECG signal using techniques developed in the field of wavelet transform analysis. Previously unreported structure within the ECG during ventricular fibrillation (VF) is found using a high-resolution decomposition of the signal employing the continuous wavelet transform. We believe that wavelet transform methods could lead to the development of powerful tools for use in the resuscitation of patients with cardiac arrest.

Outcome from a rapid-assessment chest pain clinic.

Chest pain accounts for much of the rising numbers of emergency admissions, but in-patient assessment is not necessarily the best way of dealing with these patients. We ran a 'rapid-assessment chest pain clinic' to provide an alternative route of assessment, and audited its outcome. General practitioners referred patients with recent-onset chest pain, increasing chest pain, chest pain at rest, or other chest pain of concern, on the understanding that they would be seen within 24 h. During 8 1/2 months, 334 patients were referred and 317 patients were seen, most of whom had exercise electrocardiography. A median of 6 months later, 278 patients were personally contacted to determine outcome. Of these, 18% had been admitted immediately with acute coronary syndromes, and 49% had been diagnosed as non-coronary chest pain (none of whom subsequently infarcted or died). Continuing symptoms were infrequent, and satisfaction was high, although 13% of patients had been revascularized. A significant number of patients required immediate admission and/or ultimate revascularization, but many more did not. The majority of these patients had non-coronary chest pain, and this diagnosis was substantiated by their excellent outcome and (in some cases) by further investigation.

A comparison of alternative arrangements for an out-of-hours chemical pathology service.

Until 1979, the out-of-hours chemical pathology service was the conventional on-call service in which the medical laboratory scientific officers (MLSOs) carried out analyses at the direct request of clinical staff. In 1980, during an industrial dispute, junior ward doctors were trained to use three simple instruments which are maintained by the chemical pathology department. In January, 1981, when the dispute was settled, the doctors continued to use these instruments. Analyses they could not make were done by the MLSO on call, but only after the requests were monitored by a chemical pathologist or biochemist. The result was an 80% reduction in the number of calls. When the monitoring was withdrawn in 1983, there was some increase in the number of MLSO calls, but this was still 35% less than that with the conventional system despite a 4-fold increase in the total number of analyses done out of hours between 1979 and 1984. Surveys in 1984 and in early 1985 revealed that most doctors preferred using the instruments to asking an MLSO to make the analysis.

The heterogeneity of essential hypertension. Relation between lithium efflux and sodium content of erythrocytes and a family history of hypertension.

The lithium efflux and sodium content of erythrocytes were measured in 75 patients with untreated essential hypertension. The average values of both were higher than those of normotensive control subjects. Values above the range in the controls were found only in patients with a family history of hypertension, and in these the frequency of raised lithium efflux was 76% and of raised sodium content was 36%. Measurement of lithium efflux and sodium content, together with the family history, allows patients with essential hypertension to be categorised into four groups.

Helix packing and subunit conformation in horse spleen apoferritin.

An electron density map of horse spleen apoferritin at 0.28-nm (2.8 A) resolution and its preliminary interpretation have been described previously. Rigorous examination of this and newer maps at the same nominal resolution but calculated from more extensive data sets, including model building in a Richards' comparator, now allows us to report on structural features in more detail. We list inter-helical angles within and between neighbouring subunits, and describe a new short region of inter-subunit anti-parallel pleated sheet. A short section of electron density not properly accounted for in the first model has also been found. We also report on two alternative ways of connecting helical regions which account almost equally well for the observed electron density, and we assess these two alternative conformations and compare them with the conformations of other known proteins.