Techniques for operative reduction of pubic symphysis disruptions.

Occasionally, a pelvic fracture is an exceedingly difficult injury to manage in the multiple trauma victim. Accompanying hemorrhage can not only be life-threatening but often confuses the evaluation as to sources of blood loss. Reduction of a Malgaigne's or open book pelvic fracture aids significantly in stemming this extraperitoneal venous bleeding. If operative intervention for associated injuries is required, reapproximation of any pubic disruption should be performed concomitantly. Use of the rib approximator for this reduction saves considerable time and can be accomplished with relatively little effort.

Aspergillus infection of the burn wound.

During a 15-year period, 18 patients with major burns developed a wound infection due to Aspergillus. Ages averaged 28 years, extents of burn were 54% (14-97%) BSA for total surface involvement and 42% (14-85%) BSA for full-thickness injury. Pseudomonas sepsis preceded Aspergillus infection in 16 cases. Thirteen of the episodes occurred in three epidemics, each apparently related to contaminated air-conditioner ducts and filters. Treatment was based upon wound excision in all 18 patients, with recurrence initially in each. Topical and parenteral antifungal agents were never individually successful in controlling the infection. Whenever fungal sepsis involved an extremity alone and thus amputation could rid the body of the entire infected site, survival could then be achieved. The overall mortality rate was 78%. Protection of the wound from Aspergillus colonization appeared to be the only reliable method of preventing this often lethal fungus infection.

Noninvasive external recording of cardiac conduction system (His bundle) activity.

Successful and adequate external recording of the cardiac conduction system from the body's surface can be accomplished in 80 to 90 percent of subjects studied. High-gain amplification, signal averaging, and triggering with a conditioned QRS signal results in good recording reproducibility. Averaging of 128 consecutive cycles is adequate, but on occasion averaging of 256 cycles may yield better results. The patients's QRS signal triggers the transfer of signals, which are digitized and stored during the preceding P-R interval. Comparison of external recordings with direct invasive recordings in animals and patients shows good correlation between the major His bundle deflections. The advantages of the system developed include its mobility, triggering the QRS with pretrigger data processing, and instantaneous display on Polaroid photograph. Future research should concentrate on further miniaturization and simplification of the instrumentation, detailed experimental comparison between direct and external recordings for identification of deflections and their origin, further study of the recording lead system, and the most appropriate method of information display.

Noninvasive recording of His-Purkinje activity in man by ORS-triggered signal averaging.

Mobile instrumentation and a clinically applicable method have been developed for external His bundle recording. High gain signal amplification (10)(5) filtering (30--300 HZ) and averaging (128 or 256 consecutive cycles) are used. Acquisition of signals arising in the P-R interval is triggered by the patient's QRS signal at the end of that interval. The precordial bipolar electrodiogram is digitized at 5k HZ with 8 bit resolution and transferred to a 1,024 word, 18 bit signal averager. The averaged signal is then displayed on an oscilloscope and photographed. Good correlations were obtained between direct intracardiac and precordial recordings in experimental animals and in humans. Noise level after averaging was below 0.3 microV, and there was good elimination of asynchronous atrial and ectopic ventricular activity. With averaging of 128 or 256 consecutive cycles, the signal attenuation after propagation to the chest wall was in the range 1:2000 to 1:4000 in comparison with the directly recorded His bundle activity deflections. The noninvasive method may be of value in follow-up of acute and chronic disturbances of atrioventricular conduction, as well as in studies of effects of pharmacologic interventions.

A tool and an instrument modification to facilitate aortic flow probe placement.

A tool was designed and fabricated to simplify the procedure of placing a flow probe around the aortic root in acute animal experiments. The tool was made from a section of silicone rubber tubing which was flattened and tapered at one end. The flow probe was inserted into the open end of the tool, and the tapered end was drawn under the aorta, thus pulling the probe into position. Grooves were also ground into the probe body to ease the installation of the slot cover. During the 2 years that the tool and modified probes were used, they saved time and eliminated rupture of vessels as complications of aortic root flow probe placement.

Hemodynamic effects of venous valves in aorto-coronary bypass grafts.

Use of the saphenous vein in aorto-coronary bypass surgery for treatment of occlusive coronary artery disease is a well-established technique. Use of the mammary artery for the same purpose has also been favorably reported. This study was undertaken to determine whether a vein graft containing a valve would have an added advantage. A comparison of the effect of competent and incompetent valves in vein grafts on the hemodynamics of coronary circulation was made. In a group of 18 dogs, a 5 cm. portion of each dog's cephalic vein containing a valve was used in a single aorto-coronary bypass graft. Flow measurements were made between the valve and the anastomosis of the graft to the left anterior descending coronary artery (LAD). The valve was made temporarily incompetent by the insertion of a spring wire basket, 3.5 mm. in diameter, through the valve via a side branch. The flow of blood through the venous graft with the competent valve was 11.0 +/- 2.6 per cent higher than with the incompetent valve. An analysis of flow patterns showed that this increased flow could be attributed to a reduction of backflow during systole and an increase in forward diastolic flow. Results suggest that postoperative myocardial perfusion is enhanced by the presence of valves in aorto-coronary bypass vein grafts.

Demonstration of lack of persistence of effectiveness of intra-aortic balloon pumping of short duration in acute myocardial ischemia.

Experimental studies were carried out to quantitate the effectiveness of intra-aortic balloon pumping (ABP) in reducing severity and extent of myocardial ischemia and the persistence of induced changes after cessation of pumping. Ligation of the anterior descending coronary artery was followed by one hr of observation, IABP for one hr (12 dogs) or 3 hrs (12 dogs) and an additional one hr of observation. Epicardial mapping utilizing 20 electrodes was used to obtain the ST segment elevations (Sigma ST) and numbers of electrodes showing ischemic ST CHANGES (NST) in each group. Reductions of SigmaST of approximately 15% and 33% and reduction of NST of 15% and 20% was observed in the one and 3 hr groups respectively, and persisted throughout the period of pumping. Both parameters were noted to increase within 5 mins after cessation of IABP in both groups. SigmaST frequently rose to almost pre-IABP values in the group pumped for one hr. The group pumped for 3 hrs showed SigmaST increase of approximately 15% and NST increase of approximately 16%. Hemodynamic measurements showed in both groups a mean systolic unloading of approximately 10% and 10-20% mean diastolic augmentation. In conclusion, IABP of short duration (1-3 hrs) early after the onset of acute ischemis (one hr) induces a significant but transient decrease in SigmaST and NST, which reflects a reduction in myocardial ischemia. Further study is required to evaluate the effectiveness of intra-aortic balloon pumping, if intitated several hours after the onset of ischemia, to reproduce the clinical reality of a patient with an acute myocardial infarction.