A survey of resuscitation training in Canadian undergraduate medical programs.
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Canada↗
Biomedical subjects
J M Christenson
Publications and source records attributed to J M Christenson.
A non-linear programming method for optimizing parallel-hole collimator design.
A new method for optimizing the design of multi-aperture parallel-hole collimators for the gamma scintillation camera is presented. The method takes into account the frequency spectrum of a plane source object distribution as well as the energy of the radiation. A frequency dependent statistical figure of merit is calculated and combined with a weighted object distribution frequency spectrum to obtain an objective function which, when maximized, yields the optimum collimator design according to the chosen criteria. The optimization is performed by means of a sequential pattern search technique. The results show a positive correlation between te objective function and an experimental performance index evaluated for existing collimators. The optimal designs obtained by maximizing the objective function, under the assumption of no scatter within the source, exhibit somewhat higher sensitivity and lower resolution than the commercial low energy collimators tested. It is concluded that much of the resolution capability of very high resolution collimators is unused because of the limitation imposed by the intrinsic resolution of the detector assembly.
Computers↗
Abdominal compressions during CPR: hemodynamic effects of altering timing and force.
To determine the optimal method of applying abdominal compressions during cardiopulmonary resuscitation (CPR), 3 levels of pressure (25, 50, and 100 torr) were applied to the abdomen a) continuously and b) as 500 msec pulses at 10 different phases during the CPR cycle in 8 anesthetized dogs. Thoracic aortic (Ao) and right atrial (RA) pressures were measured and PAo-PRA was calculated as the coronary perfusion gradient. A pneumatic piston device provided external chest compression (60/min, 120 lbs, for 50% of the cycle) and ventilation (80% O2, 12/min, at 20cm, H2O). Another identical device provided abdominal compression (AC) via an air-filled bladder. High-pressure (100 torr) AC applied for 500 msec commencing 200 msec prior to chest compression demonstrated the best overall profile, raising mean aortic pressure 26 torr (P less than 0.001) and peak coronary perfusion gradient pressure 17 torr (P less than 0.02) from control values during standard CPR of 58 and 41 torr, respectively. We conclude that applying high-pressure, 500-msec pulses of AC 200 msec before chest compressions significantly improves CPR hemodynamics.
Abdomen↗