AMSA is highly associated with pre-hospital ROSC, survival to hospital admission, and hospital discharge in witnessed VF OHCA. Future studies are needed to determine whether AMSA computed during resuscitation can identify patients for whom continuing current resuscitation efforts would likely be futile.
Background:
Previous investigations in human out of hospital cardiac arrest (OHCA) due to ventricular fibrillation (VF) have shown that the frequency-based waveform characteristic, amplitude spectral area (AMSA) predicts defibrillation success and is associated with survival to hospital discharge. We evaluated the relative strength of factors associated with hospital discharge including witnessed/unwitnessed status, chest compression (CC) quality and AMSA. We then investigated if there is a threshold value for AMSA that can identify patients who are unlikely to survive.
Methods:
Adult OHCA patients (age ≥18), with initial rhythm of VF from an Utstein-Style database (collected from 2 EMS systems) were analyzed. AMSA was measured from the waveform immediately prior to each shock, and averaged for each individual subject (AMSA-ave). Univariate and stepwise multivariable logistic regression, and receiver-operator-characteristic (ROC) analyses were performed. Factors analyzed: age, sex, witnessed status, time from dispatch to monitor/defibrillator application, number of shocks, mean CC rate, depth, and release velocity (RV).
Results:
140 subjects were analyzed, [104 M (74%), age 62 ± 14 yrs, witnessed 65%]. Survival was 38% in witnessed and 16% in unwitnessed arrest. In univariate analyses, age (P=0.001), witnessed status (P=0.009), AMSA-ave (P<0.001), mean CC depth (P=0.025), and RV (P< 0.001) were associated with survival. Stepwise logistic regression identified AMSA-ave (P<0.001), RV (P=0.001) and age (P=0.018) as independently associated with survival. The area under the curve (ROC analysis) was 0.849. The probability of survival was < 5% in witnessed arrest for AMSA-ave < 5 mV-Hz, and in unwitnessed arrest for AMSA-ave < 15 mV-Hz.
Conclusion:
In OHCA with an initial rhythm of VF, AMSA-ave and CC RV are highly associated with survival. Further study is needed to evaluate whether AMSA-ave may be useful to identify patients highly unlikely to survive.
Purpose:
To evaluate the variations in dwell times and doses expected when using an episcleral brachytherapy device for treatment of neovascular agerelated macular degeneration (n‐AMD) based on accurate imaging modalities
Methods:
Data from 40 eyes from 40 subjects with known n‐ AMD acquired through the Distance of Choroid Study (DOCS) conducted at Moorfields Eye Hospital was used to determine the target depth; the distance from the outer scleral surface of the eye, through the choroid, to the apex of the choroidal neovascularization (CNV). Each subject underwent, in triplicate, enhanced‐depth Spectral Domain Optical Coherence Tomography (SD‐OCT), Swept Source Optical Coherence Tomography, (SS‐OCT) and Ocular Ultrasound (O‐US). These data are the most comprehensive and accurate measurements of the dimensions of the CNV and adjacent layers of the eye for this cohort of patients. During treatment of n‐AMD, patients receive a dose of 24Gy to the apex at the target depth. Using the percentage depth dose for a Sr‐90 episcleral brachytherapy device, dwell times and doses to the apex were computed to determine the expected variations.
Results:
The mean target depth and the 95% confidence interval (CI) determined by combining O‐US with SD‐OCT were 1326 (956,1696)µm and with SS‐OCT were 1332 (970,1693)µm. The calculated corresponding mean dwell times and 95% (CI) were 334 (223,445)s and 335 (226,445)s for SD‐OCT and SS‐OCT determined depths, respectively. The corresponding mean apex dose and 95% (CI) were 24 (35.9,18.0)Gy (SD‐OCT) and 24 (35.6,18.1)Gy (SS‐OCT).
Conclusion:
For episcleral brachytherapy treatment of n‐AMD, using a patient population average target depth for treatment planning is inadequate, resulting in dose variations of a factor of approximately two over the 95% CI and larger variations for a nontrivial segment of the population. Each patient should have individualized imaging studies to determine the target depth for use in the dwell time calculation.
Study was sponsored by Salutaris Medical Devices, Ltd., a subsidiary of Salutaris Medical Devices, Inc. Hamilton and Marsteller are founders of Salutaris Medical Devices, Inc. Drew, McGovern and Vitali are minor equity holders in Salutaris Medical Devices, Inc.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.