Amplitude spectral area of ventricular fibrillation can discriminate survival of patients with out-of-hospital cardiac arrest.

Background: Evidence of the association between AMplitude Spectral Area (AMSA) of ventricular fibrillation and outcome after out-of-hospital cardiac arrest (OHCA) is limited to short-term follow-up. In this study, we assess whether AMSA can stratify the risk of death or poor neurological outcome at 30 days and 1 year after OHCA in patients with an initial shockable rhythm or with an initial non-shockable rhythm converted to a shockable one. Methods: This is a multicentre retrospective study of prospectively collected data in two European Utstein-based OHCA registries. We included all cases of OHCAs with at least one manual defibrillation. AMSA values were calculated after data extraction from the monitors/defibrillators used in the field by using a 2-s pre-shock electrocardiogram interval. The first detected AMSA value, the maximum value, the average value, and the minimum value were computed, and their outcome prediction accuracy was compared. Multivariable Cox regression models were run for both 30-day and 1-year deaths or poor neurological outcomes. Neurological cerebral performance category 1-2 was considered a good neurological outcome. Results: Out of the 578 patients included, 494 (85%) died and 10 (2%) had a poor neurological outcome at 30 days. All the AMSA values considered (first value, maximum, average, and minimum) were significantly higher in survivors with good neurological outcome at 30 days. The average AMSA showed the highest area under the receiver operating characteristic curve (0.778, 95% CI: 0.7-0.8, p < 0.001). After correction for confounders, the highest tertiles of average AMSA (T3 and T2) were significantly associated with a lower risk of death or poor neurological outcome compared with T1 both at 30 days (T2: HR 0.6, 95% CI: 0.4-0.9, p = 0.01; T3: HR 0.6, 95% CI: 0.4-0.9, p = 0.02) and at 1 year (T2: HR 0.6, 95% CI: 0.4-0.9, p = 0.01; T3: HR 0.6, 95% CI: 0.4-0.9, p = 0.01). Among survivors at 30 days, a higher AMSA was associated with a lower risk of mortality or poor neurological outcome at 1 year (T3: HR 0.03, 95% CI: 0-0.3, p = 0.02). Discussion: Lower AMSA values were significantly and independently associated with the risk of death or poor neurological outcome at 30 days and at 1 year in OHCA patients with either an initial shockable rhythm or a conversion rhythm from non-shockable to shockable. The average AMSA value had the strongest association with prognosis.

Amplitude spectral area of ventricular fibrillation and defibrillation success at low energy in out-of-hospital cardiac arrest.

The optimal energy for defibrillation has not yet been identified and very often the maximum energy is delivered. We sought to assess whether amplitude spectral area (AMSA) of ventricular fibrillation (VF) could predict low energy level defibrillation success in out-of-hospital cardiac arrest (OHCA) patients. This is a multicentre international study based on retrospective analysis of prospectively collected data. We included all OHCAs with at least one manual defibrillation. AMSA values were calculated by analyzing the data collected by the monitors/defibrillators used in the field (Corpuls 3 and Lifepak 12/15) and using a 2-s-pre-shock electrocardiogram interval. We run two different analyses dividing the shocks into three tertiles (T1, T2, T3) based on AMSA values. 629 OHCAs were included and 2095 shocks delivered (energy ranging from 100 to 360 J; median 200 J). Both in the "extremes analysis" and in the "by site analysis", the AMSA values of the effective shocks at low energy were significantly higher than those at high energy (p = 0.01). The likelihood of shock success increased significantly from the lowest to the highest tertile. After correction for age, call to shock time, use of mechanical CPR, presence of bystander CPR, sex and energy level, high AMSA value was directly associated with the probability of shock success [T2 vs T1 OR 3.8 (95% CI 2.5-6) p < 0.001; T3 vs T1 OR 12.7 (95% CI 8.2-19.2), p < 0.001]. AMSA values are associated with the probability of low-energy shock success so that they could guide energy optimization in shockable cardiac arrest patients.

aMplitude spectral area of ventricular fibrillation and amiOdarone Study in patients with out-of-hospital cArdIaC arrest. The MOSAIC study.

Objective: Antiarrhythmic drugs are recommended for out of hospital cardiac arrest (OHCA) with shock-refractory ventricular fibrillation (VF). Amplitude Spectral Area (AMSA) of VF is a quantitative waveform measure that describes the amplitude-weighted mean frequency of VF, it correlates with intramyocardial adenosine triphosphate (ATP) concentration, it is a predictor of shock efficacy and an emerging indicator to guide defibrillation and resuscitation efforts. How AMSA might be influenced by amiodarone administration is unknown. Methods: In this international multicentre observational study, all OHCAs receiving at least one shock were included. AMSA values were calculated by retrospectively analysing the pre-shock ECG interval of 2 s. Multivariable models were run and a propensity score based on the probability of receiving amiodarone was created to compare two randomly matched samples. Results: 2,077 shocks were included: 1,407 in the amiodarone group and 670 in the non-amiodarone group. AMSA values were lower in the amiodarone group [8.8 (6-12.7) mV·Hz vs. 9.8 (6-14) mV·Hz, p = 0.035]. In two randomly matched propensity score-based groups of 261 shocks, AMSA was lower in the amiodarone group [8.2 (5.8-13.5) mV·Hz vs. 9.6 (5.6-11.6), p = 0.042]. AMSA was a predictor of shock success in both groups but the predictive power was lower in the amiodarone group [Area Under the Curve (AUC) non-amiodarone group 0.812, 95%CI: 0.78-0.841 vs. AUC amiodarone group 0.706, 95%CI: 0.68-0.73; p < 0.001]. Conclusions: Amiodarone administration was independently associated with the probability of recording lower values of AMSA. In patients who have received amiodarone during cardiac arrest the predictive value of AMSA for shock success is significantly lower, but still statistically significant.

Evaluating a training intervention for improving alignment between emergency medical telephone operators and callers: a pilot study of communication behaviours.

BACKGROUND: Calls to emergency medical lines are an essential component in the chain of survival. Operators make critical decisions based on information they elicit from callers. Although smooth cooperation is necessary, the field lacks evidence-based guidelines for how to achieve it while adhering to strict parameters of index-driven questioning. We aimed to evaluate the effect of a training intervention for emergency medical operators at a call centre in Tønsberg, Norway. The course was designed to enhance operators' communication skills for smoothing cooperation with callers. METHODS: Calls were analyzed using inductively developed coding based on the course rationale and content. To evaluate whether the course generated consolidated behavioral change in everyday practice, the independent analyst evaluated 32 calls, selected randomly from eight operators, two calls before and two after course completion. To measure whether skill attainment delayed decision making, we compared the time to the first decision logged by intervention operators to eight control operators. Analysis included 3034 calls: 1375 to intervention operators (T1 = 815; T2 = 560) and 1659 to control operators (T1 = 683; T2 = 976). RESULTS: Operators demonstrated improved behaviours on how they greeted the caller (p < .001), acknowledged the caller (p < .001), and displayed empathy (p = 0.015). No change was found in the use of open-ended questions and agreeing with the caller. Contrary to expectations, operators who took the course logged first decisions more quickly than the control group (p < .001). CONCLUSIONS: This pilot study demonstrated that the training intervention generated behavioural change in these operators, providing justification for scaling up the intervention.

Favourable outcome after 26 minutes of "Compression only" resuscitation: a case report.

CASE PRESENTATION: A 49 year old man had ventricular fibrillation in his home, at room temperature, due to an ST-elevation myocardial infarction. He received Cardiac compression only resuscitation (CC-only) for 26 minutes by his wife, followed by four minutes of standard CPR by other lay persons until EMS-arrival. Gasping and moaning were observed during most of the CC-only period. The ambulance arrived at 30 minutes. The first ECG showed a fine ventricular fibrillation. Restoration of spontaneous circulation (ROSC) was achieved at 49 minutes after a total of four defibrillatory shocks. The patient recovered without any cerebral damage, and was discharged to his home after eight days hospitalization. CONCLUSIONS: This case demonstrates that early and powerful cardiac compressions alone without rescue breaths may maintain sufficient circulation and gas exchange to prevent neurological damage for more than 25 minutes. This should be kept in mind for Emergency Medical Dispatch Centrals giving Pre-arrival instructions to bystanders.

Effect of implementing routine early invasive strategy on one-year mortality in patients with acute myocardial infarction.

The aim of the present study was to investigate whether the implementation of an early invasive strategy for unselected patients with acute myocardial infarction (AMI) would be associated with reduced long-term mortality compared to a conservative approach. In this prospective observational cohort study of consecutive patients admitted for AMI in 2003 (conservative cohort, n = 311) and 2006 (invasive cohort [IC], n = 307), an 11% absolute and 41% relative reduction in 1-year mortality was found for patients with AMI in the IC compared to the conservative cohort (p = 0.001). These findings were consistent after adjustment for age, gender, previous AMI, previous stroke, diabetes, smoking status, previous left ventricular systolic dysfunction, and serum creatinine at admission (hazard ratio 0.54, 95% confidence interval 0.38 to 0.78) and Global Registry of Acute Coronary Events risk score (hazard ratio 0.67, 95% confidence interval 0.46 to 0.97). More patients with ST-segment elevation myocardial infarction received primary percutaneous coronary intervention in the IC (57% vs 3%, p <0.001), and a sixfold (25% vs 4%, p <0.001) increase in early percutaneous coronary intervention (<72 hours) for patients with non-ST-segment elevation myocardial infarction was observed. A greater proportion of patients in the IC received clopidogrel, aspirin, and statins during follow-up; otherwise, the secondary prevention measures were similar in the 2 cohorts. In conclusion, the introduction of a strategy for routine transfer to a high-volume percutaneous coronary intervention center for early invasive therapy was accompanied by a substantial reduction in mortality among unselected patients with AMI. Differences in unmeasured confounders might have accounted for a part of the difference in outcome.

[Prehospital diagnosis and treatment of acute myocardial infarction in Vestfold]. / Prehospital diagnostikk og behandling av akutt hjerteinfarkt i Vestfold.

BACKGROUND: Pre-hospital thrombolysis is a relatively new treatment modality in Norway. The present study is a county-based evaluation of the first phase of this procedure after its introduction in 2002. MATERIALS AND METHODS: This is a retrospective cohort study of all patients who, over a nine-month period, had a pre-hospital ECG taken by paramedics and transmitted to the county's two coronary care units. The medical records of all patients who received pre-hospital thrombolysis were analysed and compared with those who received in-hospital thrombolysis over the same period. MATERIAL AND METHODS: A pre-hospital ECG was successfully taken and transmitted in 840 patients. Pre-hospital thrombolytic therapy was given to 45 (5.4%) patients, of whom 38 (84%) developed ST-elevation myocardial infarction (STEMI). Over the same period, 32 patients received in-hospital thrombolysis, of whom 28 (87%) developed STEMI. Among the 738 hospitalised patients who did not receive pre-hospital thrombolytic therapy, 218 (28%) had a diagnosis of acute coronary syndrome, 258 (35%) had established coronary heart disease but no evidence of coronary ischaemia, while 262 (36%) had no evidence of coronary heart disease at all. Median call-to-thrombolysis time was 42 minutes (range 21-75). INTERPRETATION: The findings indicate good paramedical pre-hospital routines with short call-to-thrombolysis-time, but the routines for pre-hospital ECG and thrombolytic therapy need reassessment.

[Urgent calls--prehospital response time in Vestfold and Troms in 2001]. / Når det haster--prehospitale responstider i Vestfold og Troms i 2001.

BACKGROUND: Targeted emergency medical responses with minimum time loss require a well organized emergency medical system (EMS). We studied time consumption from emergency call reception to the arrival of the ambulance unit in two dispatch centres serving two demographically different Norwegian regions. MATERIAL AND METHODS: We analysed 5004 emergency "code red" calls during 2001 processed by an EMS serving 367 000 inhabitants in 28 mixed urban/rural municipalities in Vestfold and Troms counties. Dispatch centre process time, ambulance (ground, air or boat) response time and total access times were measured. RESULTS: Total pre-hospital access time from call reception to arrival of ambulance to patient were considerably longer than the suggested national goals, which were only met in two rural areas out of the 28 municipalities studied. Median pre-hospital response time was 10 minutes in both regions. Within 12 minutes from the emergency call, 62.9% of the population in Vestfold and 59.8% in Troms were reached by ambulance. INTERPRETATION: National standards for pre-hospital response times in medical emergencies are neither met in densely populated cities, nor in less populated rural areas.