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To determine the site of persistent electrical activity during cardioplegic arrest, microelectrodes that were also capable of recording temperature were placed along the conducting system in dogs undergoing one hour of cardioplegic arrest. Electrical activity was highest in the atrioventricular (AV) junction area (AV node and proximal bundle of His), and the temperature in this area could not be lowered to the level of the temperature in the left ventricular apex by routine cardioplegic technique. Neither changing K+ concentration (16 to 20 mEq/L) nor adding procaine hydrochloride abolished the activity of the conducting system during cardioplegia, and only 2 of 15 dogs were in sinus rhythm 30 minutes after reperfusion. When the conducting system temperatures were lowered to less than 15 degrees C by right AV lavage with iced saline solution, electrical activity was abolished during arrest and all 4 of 4 animals were in sinus rhythm 30 minutes after reperfusion. This study localizes the site of persistent conducting system activity during cardioplegic arrest, confirms it can be abolished with local cooling, and establishes the relationship between conducting system activity during cardioplegia and the incidence of conduction block and junctional rhythm following reperfusion.

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Pulmonary arterial catheters have been widely accepted as useful for monitoring the critically ill patient. New modifications allowing transvenous cardiac pacing, Hiss bundle electrocardiography and continuous monitoring of mixed venous saturation promise to increase the acceptance and use of these catheters. The 52 per cent combined major and minor complication rate documented in this study suggest that enthusiasm for pulmonary arterial catheterization should be tempered with caution. Serious complications and death do occur with these devices and may be more frequent than previously recognized. Use of a pulmonary arterial catheter should be undertaken for defined indications, with a reasonable expectation of benefit from the data obtained and with a clear understanding of the risks involved.

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As part of an ongoing study of the operative treatment of colon injuries, 33 patients proved to have colon injury at operation had diagnostic peritoneal lavage as part of their preoperative examination. Gunshot wounds were the cause of injury in 22 (67%) of these patients and stab wounds in 11 patients (33%). The lavage was positive in only 23 (70%) of the 33 patients with operatively proved penetrating injuries of the colon. Lavage was accurate in 16 (73%) of 22 patients with gunshot wounds of the colon and seven (64%) of 11 patients with stab wounds. The overall false-negative rate for this series of patients was 30%. This study indicates that diagnostic peritoneal lavage is relatively inaccurate in the evaluation of colonic injury secondary to penetrating abdominal trauma.

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The clinical course and final outcome were determined for 63 trauma victims who underwent resuscitative thoracotomy (RT) for hypovolemic cardiac arrest in the Department of Emergency Medicine during a 24-month period. The objectives of the study were to determine the efficacy of and indications for RT and to define the prognostic signs for survival. Of 63 patients, six were successfully resuscitated (9.5%), and five of these were discharged from the hospital (7.9%). The presence of pupillary reactions was an extremely reliable indicator of successful outcome (P = 0.0009), as was the presence of some respiratory effort (P = 0.025). None of the victims of blunt trauma (n = 6) or severe head injury (n = 13) survived. Three of 17 patients (17.6%) with stab wounds and two of 36 (5.6%) with gunshot wounds survived the procedure. RT was beneficial in 13.6% of patients who had isolated organ system injuries, but no patient with injuries to more than two organ systems survived. Victims of isolated penetrating thoracic trauma had an 11.8% survival rate, as opposed to a 0% survival rate for those with abdominal trauma. The best prognosis was in victims with penetrating cardiac injuries, who had a 22.7% survival rate. The cost of RT averaged $1660 per patient, exclusive of physician charges. In our experience, RT is most beneficial for victims of penetrating thoracic trauma, especially those with cardiac injuries. However, routine use of this high cost/low benefit procedure cannot be recommended for patients who have cardiac arrest secondary to blunt trauma or severe head injuries. Also, it is not recommended for patients whose pupillary reflexes and respiratory movements are absent.

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A subset of ten consecutive patients who had sustained penetrating and blunt abdominal trauma came to the hospital with stable vital signs. None had any clinical evidence of intraperitoneal injury. All patients underwent peritoneal lavage, and surgical exploration was performed on the basis of a 100,000/cu mm in the effluent. Substantial intraperitoneal injury was found in nine of ten patients. We suggest that as a further refinement of peritoneal lavage, in addition to RBC count, the WBC count be measured in the effluent fluid and if it is found to be greater than 500/cu mm, surgical exploration be carried out.

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To achieve synchronized differential pulmonary ventilation, an Ohio 560 ventilator was modified through separation of the outputs of the deep breath bellows and the tidal volume bellows and providing independent volume, flow rate, PEEP, oxygen-humidification, and alarm systems. The described ventilator modification is simple, inexpensive, and does not alter the performance characteristics of the original unmodified ventilator. Differential lung ventilation may be more easily achieved with this modified ventilator than with the simultaneous use of two ventilators or external electronic synchronizers.

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This work studies the effect of hyaluronidase on myocardium subjected to long-term aortic cross-clamping (three hours) and moderate hypothermia (28 degrees C). Animals receiving hyaluronidase (1,00o U per liter) through the root of the aorta with a procaine-potassium chloride-lasmalyte cardioplegic solution showed better functional, electrical, and morphological response than the untreated animals. These findings, although preliminary, appear to be promising for potential clinical application.

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