Bystander-initiated chest compression-only CPR is better than standard CPR in out-of-hospital cardiac arrest.

INTRODUCTION: Out-of-hospital cardiac arrest has a low survival rate to hospital discharge. Recent studies compared a simplified form of CPR, based on chest compression alone versus standard CPR including ventilation. We performed systematic review and meta-analysis of randomized controlled trials, focusing on survival at hospital discharge. METHODS: We extensively searched the published literature on out-of hospital CPR for non traumatic cardiac arrest in different databases. RESULTS: We identified only three randomized trials on this topic, including witnessed and not-witnessed cardiac arrests. When pooling them together with a meta-analytic approach, we found that there is already clinical and statistical evidence to support the superiority of the compression-only CPR in terms of survival at hospital discharge, as 211/1842 (11.5%) patients in the chest compression alone group versus 178/1895 (9.4%) in the standard CPR group were alive at hospital discharge: odds ratio from both Peto and DerSimonian-Laird methods =0.80 (95% confidence interval 0.65-0.99), p for effect =0.04, p for heterogeneity =0.69, inconsistency =0%). CONCLUSIONS: Available evidence strongly support the superiority of bystander compression-only CPR. Reasons for the best efficacy of chest compression-only CPR include a better willingness to start CPR by bystanders, the low quality of mouth-to-mouth ventilation and a detrimental effect of too long interruptions of chest compressions during ventilation. Based on our findings, compression-only CPR should be recommended as the preferred CPR technique performed by untrained bystander.

The use of a radiochromic detector for the determination of stereotactic radiosurgery dose characteristics.

The measurement of absorbed dose as well as dose distributions (profiles and isodose curves) for small radiation fields (as encountered in stereotactic surgery) has been difficult due to the usual large detector size or densitometer aperture (> 1 mm) relative to the radiation field (as small as 4 mm). The radiochromic direct-imaging film, when read with a scanning laser microdensitometer (laser beam diameter 0.1 mm), overcomes this difficulty and has advantages over conventional film in providing improved precision, better tissue equivalence, greater dynamic range, higher spatial resolution, and room light handling. As a demonstration of suitability, the calibrated radiochromic film has been used to measure the dose characteristics for the 18-, 14-, 8-, and 4-mm fields from the gamma-ray stereotactic surgery units at Mayo Clinic and the University of Pittsburgh. Intercomparisons of radiochromic film with conventional methods of dosimetry and vendor-supplied computational dose planning system values indicate agreement to within +/- 2%. The dose, dose profiles, and isodose curves obtained with radiochromic film can provide high-spatial-resolution information of value for acceptance testing and quality control of dose measurement and/or calculation.

Beam profile analysis using GafChromic films.

GafChromic film dosimetry techniques were used to evaluate the beam profiles for each collimator of the Leksell Gamma Knife at the University of Kentucky Medical Center. At the conclusion of acceptance testing, representatives from Leksell exposed conventional films for beam profile processing and analysis in Sweden. At the same time, an inhouse technique using GafChromic films was utilized in the analysis of the beam profiles. GafChromic films were irradiated to 100 Gray to provide data in each of the three planes for each collimator size. The films were analyzed using a scanning helium-neon laser densitometer with a small aperture of 5-10 microns. The digitized density profiles were curve-fitted using a PC plotting algorithm. The curve-fitted density profiles were converted to relative dose using a standard calibration curve determined with a conventional cobalt-60 teletherapy beam. The results are in excellent agreement with the conventional film analysis reported by Leksell. The GafChromic method has proven to be an accurate and rapid method of analysis and could be easily incorporated into a quality assurance program.

A new method for characterizing beta-ray ophthalmic applicator sources.

A technique is described which enables one to obtain detailed dose characteristics of 90Sr beta-ray ophthalmic applicators. A radiochromic radiation detector which is a solid-state solution of hexahydroxyethyl pararosaniline cyanide in a nylon polymer (i.e., thin foil), has been used to determine the surface dose rate and dose distribution of these sources. The detectors are rugged, easily handled, have an equivalent response (optical density per unit absorbed dose) to photons and electrons, and produce high-resolution images. They have been found useful for this application due to the high surface dose rates [0.10-1.0 Gy (H2O)/s] and their low sensitivity (approximately 10(4) Gy for an optical density of 1.0). The foils have been evaluated on a He-Ne scanning laser densitometer with a resolution of 0.3 mum. Comparison with NIST (formerly NBS) extrapolation ionization chamber measurements indicates surface dose-rate agreement within 6%. Spectral dosimetric characteristics are presented and discussed.