Early versus Later Rhythm Analysis in Patients with Out-of-Hospital Cardiac Arrest

Background In a departure from the previous strategy of immediate defibrillation, the 2005 resuscitation guidelines from the American Heart Association–International Liaison Committee on Resuscitation suggested that emergency medical service (EMS) personnel could provide 2 minutes of cardiopulmonary resuscitation (CPR) before the first analysis of cardiac rhythm. We compared the strategy of a brief period of CPR with early analysis of rhythm with the strategy of a longer period of CPR with delayed analysis of rhythm. Methods We conducted a cluster-randomized trial involving adults with out-of-hospital cardiac arrest at 10 Resuscitation Outcomes Consortium sites in the United States and Canada. Patients in the early-analysis group were assigned to receive 30 to 60 seconds of EMS-administered CPR and those in the later-analysis group were assigned to receive 180 seconds of CPR, before the initial electrocardiographic analysis. The primary outcome was survival to hospital discharge with satisfactory functional status (a modified Rankin scale score of ≤3, on a scale of 0 to 6, with higher scores indicating greater disability). Results We included 9933 patients, of whom 5290 were assigned to early analysis of cardiac rhythm and 4643 to later analysis. A total of 273 patients (5.9%) in the later-analysis group and 310 patients (5.9%) in the early-analysis group met the criteria for the primary outcome, with a cluster-adjusted difference of −0.2 percentage points (95% confidence interval, −1.1 to 0.7; P=0.59). Analyses of the data with adjustment for confounding factors, as well as subgroup analyses, also showed no survival benefit for either study group. Conclusions Among patients who had an out-of-hospital cardiac arrest, we found no difference in the outcomes with a brief period, as compared with a longer period, of EMS-administered CPR before the first analysis of cardiac rhythm. (Funded by the National Heart, Lung, and Blood Institute and others; ROC PRIMED ClinicalTrials.gov number, NCT00394706.

Surrogate markers of transport distance for out-of-hospital cardiac arrest patients

Background. Transport of out-of-hospital cardiac arrest (OHCA) patients expeditiously to appropriately equipped hospitals is of paramount importance. Objective. We sought to test the correlation of the centroids of geographic units with the actual transport distance for OHCA patients in order to determine the most appropriate surrogate marker of location for future planning, protocol development, and research projects. Methods. This was a prospective, observational analysis of OHCA events in Portland, Oregon. Using geographic information systems (GISs), the locations of OHCA events and receiving hospitals were identified and geocoded for visual inspection and analysis. Transport distance was calculated via network transport distance and Euclidean distance from multiple surrogate markers of location (centroids of ZIP code, census tract, census block group, and census block). Actual distance from the location of the event was then compared with these surrogate markers to determine the accuracy of alternative markers of OHCA location. Results. Two hundred seventy patients had location data recorded, 163 of whom were transported to a hospital for further care. The median transport distance was 5.17 miles. The transport distance of OHCA patients from the centroid of the census block had the best correlation (R2 = 0.99) with actual transport distance, whereas the use of the centroid of ZIP codes as a surrogate location had the lowest correlation (R2 = 0.21). Conclusions. The use of centroids of census blocks via network distance is a valid surrogate for actual location of an OHCA event when calculating transport distance

Injured Older Adults Transported by Emergency Medical Services: One Year Outcomes by POLST Status

Background: Advance care planning documents, including Physician Orders for Life-Sustaining Treatment (POLST), are intended to guide care near end of life, particularly in emergency situations. Yet, research on POLST during emergency care is sparse. Methods: A total of 7,055 injured patients age ≥ 65 years were transported by 8 emergency medical services (EMS) agencies to 23 hospitals in Oregon. We linked multiple data sources to EMS records, including: the Oregon POLST Registry, Medicare claims data, Oregon Trauma Registry, Oregon statewide inpatient data, and Oregon vital statistics records. We describe patient and event characteristics by POLST status at time of 9-1-1 contact, subsequent changes in POLST forms, and mortality to 12 months. Results: Of 7,055 injured older adults, 1,412 (20.0%) had a registered POLST form at the time of 911 contact. Among the 1,412 POLST forms, 390 (27.6%) specified full orders, 585 (41.4%) limited interventions, and 437 (30.9%) comfort measures only. By one year, 2,471 (35%) patients had completed POLST forms. Among the 4 groups (no POLST, POLST-full orders, POLST-limited intervention, POLST-comfort measures), Injury Severity Scores were similar. Mortality differences were present by 30 days (5.0%, 4.6%, 8.0%, and 13.3%, p \u3c 0.01) and were greater by one year (19.5%, 23.9%, 35.4%, and 46.2%, p \u3c 0.01). Conclusions: Among injured older adults transported by ambulance in Oregon, one in 5 had an active POLST form at the time of 9-1-1 contact, the prevalence of which increased over the following year. Mortality differences by POLST status were evident at 30 days and large by one year. This information could help emergency, trauma, surgical, inpatient, and outpatient clinicians understand how to guide patients through acute injury episodes of care and post-injury follow up

Enhancing ventilation detection during cardiopulmonary resuscitation by filtering chest compression artifact from the capnography waveform

<div><p>Background</p><p>During cardiopulmonary resuscitation (CPR), there is a high incidence of capnograms distorted by chest compression artifact. This phenomenon adversely affects the reliability of automated ventilation detection based on the analysis of the capnography waveform. This study explored the feasibility of several filtering techniques for suppressing the artifact to improve the accuracy of ventilation detection.</p><p>Materials and methods</p><p>We gathered a database of 232 out-of-hospital cardiac arrest defibrillator recordings containing concurrent capnograms, compression depth and transthoracic impedance signals. Capnograms were classified as non-distorted or distorted by chest compression artifact. All chest compression and ventilation instances were also annotated. Three filtering techniques were explored: a fixed-coefficient (FC) filter, an open-loop (OL) adaptive filter, and a closed-loop (CL) adaptive filter. The improvement in ventilation detection was assessed by comparing the performance of a capnogram-based ventilation detection algorithm with original and filtered capnograms.</p><p>Results</p><p>Sensitivity and positive predictive value of the ventilation algorithm improved from 91.9%/89.5% to 97.7%/96.5% (FC filter), 97.6%/96.7% (OL), and 97.0%/97.1% (CL) for the distorted capnograms (42% of the whole set). The highest improvement was obtained for the artifact named type III, for which performance improved from 77.8%/74.5% to values above 95.5%/94.5%. In addition, errors in the measurement of ventilation rate decreased and accuracy in the detection of over-ventilation increased with filtered capnograms.</p><p>Conclusions</p><p>Capnogram-based ventilation detection during CPR was enhanced after suppressing the artifact caused by chest compressions. All filtering approaches performed similarly, so the simplicity of fixed-coefficient filters would take advantage for a practical implementation.</p></div

Examples of filtering performance.

<p>Original capnogram with clean and distorted respiration cycles (top panel). Detected ventilations are depicted with vertical lines. Distorted ventilations could not be detected by the algorithm. Lower panels show the filtered capnogram (in blue) superimposed to the original capnogram (in gray), for the three filtering alternatives. Detected ventilations are depicted with vertical red dashed lines. In this example, all ventilations were correctly detected after filtering.</p