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Biomedical subjects

C Mavroudis

Publications and source records attributed to C Mavroudis.

At least 127 records · Page 7Linked to original sources
PubMed1987

Experimental aerobic-anaerobic thoracic empyema in the guinea pig.

The clinical and pathological features of experimental aerobic-anaerobic thoracic empyema in the Duncan-Harley guinea pig are described. Thoracic empyema development and early death (less than 14 days after bacterial inoculation) were noted after various concentrations and species were inoculated into the pleural space with a piece of umbilical tape, which was used as a cofactor. The effect of concomitant hemothorax was also tested. Gram-negative infection was found to have a more virulent course than Gram-positive infection in the thoracic cavity. Moreover, these findings support the thesis that intrathoracic inoculation of anaerobic bacteria, even in combination with other anaerobic species, fails to produce clinical empyemas. However, anaerobic bacteria appear to enhance synergistically the virulence of sublethal and subempyema-forming concentrations of aerobic bacteria such as Staphylococcus aureus and Escherichia coli.

Animals↗
PubMed1987

Nitroprusside abolishes the deleterious effects of surface cooling-induced hypothermia on immature pigs with ventricular septal defects.

The efficacy of systemic hypothermia in combination with cardiopulmonary bypass for the repair of congenital cardiac malformations is established. Surface cooling in infants with ventricular septal defects as a prebypass adjunct has been associated with visceral ischemic complications. Surface cooling in infant pigs with ventricular septal defects results in increased systemic vascular resistance and unchanged pulmonary vascular resistance with increased left-to-right shunting and a maldistribution of blood flow away from the viscera and kidneys. This study was to determine whether nitroprusside ameliorates the deleterious effects of increased systemic vascular resistance during hypothermia in infant pigs with ventricular septal defects. Nine neonatal pigs (4 weeks, 4 kg) had experimental ventricular septal defects resulting in a 2.3 +/- 0.3: 1 shunt. Systemic and pulmonary vascular resistances were determined by the flow probe and microsphere techniques. Systemic and pulmonary blood flow distributions were measured by the microsphere technique. Left-to-right shunt ratios were determined by oximetry, flow probe, and microsphere. The pigs were cooled to 28 degrees C and measurements were made at 37 degrees, 32 degrees, and 28 degrees C. We found that nitroprusside abolishes the deleterious effects of surface cooling by blocking the rise of systemic vascular resistance without significant changes in aortic pressure. As a result, the animals maintained control pulmonary-to-systemic flow levels and maintained control levels of oxygen delivery while showing a decline in oxygen consumption. Additionally, the vasodilatory effect allowed the animals to cool twice as fast as animals without nitroprusside. Regional blood flow distribution as percent cardiac output and absolute tissue flow were protected during surface cooling. This technique may have a role in cardiac operations on infants with left-to-right shunts.

Animals↗
PubMed1986

The first 70 years experience managing cardiac disruption due to penetrating and blunt injuries at the University of Louisville.

Survival of patients with cardiac injuries requires prompt intervention and cardiography. Approximately 50 years ago, Dr. R. Arnold Griswold instituted a treatment plan for the management of cardiac injuries. Many of the tenets he espoused are still in use today. We have been able to collect data on 266 patients with heart wounds from 1913 to 1982 at Louisville General Hospital. Trends in the evolution of injury patterns and their treatment will be discussed.

Cardiac Surgical Procedures↗
PubMed1985

The effect of surface cooling on blood flow distribution in infant pigs with mature left to right shunts.

Surface cooling as an adjunct to cardiopulmonary bypass, core cooling, and circulatory arrest has been effectively used to produce more homogeneous cooling and better tissue preservation. A previous study, using pigs with newly created aortopulmonary shunts, revealed a redistribution of blood flow away from the kidneys and viscera during surface cooling that did not occur in normal pigs. The present study tests the hypothesis that pigs with mature aortopulmonary shunts behave in a similar manner. Group I (N = 7, unshunted pigs) and Group II (N = 7, shunted pigs) underwent surface cooling and blood flow distribution measurements by microspheres at 37, 32, 28, and 25 degrees C. Both Groups I and II experienced a decrease in cardiac output with hypothermia. Group II had decreased absolute tissue flow to the viscera, kidneys, muscle, and skin at 37 degrees C compared with Group I, even before the onset of hypothermia. During hypothermia, Group I experienced a decrease in all tissue flows, but Group II had a decrease only in visceral and renal flows at 25 degrees C. Blood flow distribution, as a percentage of cardiac output, showed little change (decrease only in skin) in Group I with hypothermia. In Group II, however, a maldistribution of cardiac output developed resulting in decreased percentage of cardiac output to the kidneys and viscera and an increased percentage of cardiac output to the lungs that was confirmed by an increase in the Qp/Qs ratio.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Developmental sequelae in premature infants undergoing ligation of patent ductus arteriosus.

One hundred sixteen infants who underwent on-unit ligation of patent ductus arteriosus (PDA) were examined for developmental sequelae. Mean gestational age of the study group was 29.1 weeks; mean birth weight, 1,232 gm; and mean duration of follow-up, 20.7 months (chronological age). Seven infants died of severe bronchopulmonary dysplasia (4) and severe central nervous system dysfunction (3) before they were 3 years old. Sixty-five percent of the remaining infants exhibited normal motor and mental development, although 58% showed some degree of postnatal growth retardation. There was no evidence of left arm dysfunction caused by the thoracic incision; 3 infants had minor problems with nonabsorbed sutures at 3 to 6 months of age. No infant demonstrated recurrence of ductal patency. Mild sensorineural handicaps not expected to be of long-term importance were noted in 20 infants. Eighteen other infants (15.5%) were classified as having moderate to severe impairments, which may have substantial impact on development and ability to function. Surgical ligation of PDA in premature infants has been shown to be safe and effective in the short run. Long-term follow-up suggests that infants who undergo PDA ligation do not appear to be at increased risk for sensorineural handicaps.

Birth Weight↗
PubMed1985

Effect of hemothorax on experimental empyema thoracis in the guinea pig.

An experimental model for empyema thoracis in the Duncan-Harley guinea pig is introduced. Empyema thoracis development and early death (less than 14 days after bacterial inoculation) were noted after various concentrations and species were inoculated into the pleural space with a piece of umbilical tape, which was used as a cofactor. The effect of concomitant hemothorax was also tested. Group I (N = 90) had intrapleural inoculation of umbilical tape and various concentrations (10(4), 10(6), 10(8) organisms/ml) of various bacterial species, which included Staphylococcus aureus (N = 30), Escherichia coli (N = 30), and Bacteroides fragilis (N = 30). Group II (N = 90) had intrapleural inoculation of umbilical tape, 1 ml of autologous blood, and the same varying concentrations and species of bacteria as Group I. The observation period was 14 days, during which time early deaths were noted. Fifty-eight percent of the staphylococcal group of animals, 37% of the E. coli group of animals, and none of the B. fragilis group of animals developed empyema. Animals with empyema developed significant weight loss (p less than 0.05) and roentgenographic evidence of empyema, which was supported by postmortem pleural reaction and pneumonia scores (p less than 0.05). Higher concentrations of inoculated bacteria produced a higher incidence of empyema in the S. aureus and E. coli groups (p less than 0.05), but concomitant hemothorax did not increase the already high incidence of empyema and early death in the E. coli group. Empyema caused by B. fragilis did not develop, even with cofactors of umbilical tape and blood. Anaerobic infections in this model may require the presence of other aerobic or facultative organisms, the presence of necrotic lung, prior malnutrition, or a combination thereof.

Animals↗
PubMed1985

Emergency pneumonectomy for penetrating and blunt trauma.

Emergency pneumonectomy for penetrating and blunt trauma has an attendant high mortality. Patients with major lung injuries presenting with prolonged shock followed by control of bleeding, resuscitation with or without aortic cross-clamping and pneumonectomy have had uniformly unsatisfactory results. From 1972 to 1982, eight patients at the University of Louisville Hospital underwent emergency pneumonectomy. All patients underwent expeditious evaluation, resuscitation, and thoracotomy with pneumonectomy. Three patients died of exsanguination (2 patients had major associated intra-abdominal injuries). Three other patients died due to pulmonary edema and right ventricular failure 2 to 3 hours after hemorrhage had been controlled and intravascular volume restored. Aortic cross-clamping was employed in four patients due to persistent hypovolemia with 100 per cent mortality. Of the two surviving patients, one presented with stable blood pressure and had pneumonectomy for tracheobronchial disruption, while the other had pneumonectomy for tangential laceration of the lung at the hilum. Pulmonary edema and right ventricular failure were responsible for mortality following emergency pneumonectomy and control of hemorrhage and restoration of blood volume. The addition of aortic cross-clamping did not seem to alter survival and may, indeed, hinder therapy due to increased vascular afterload and increased heart failure and pulmonary edema.

Adult↗
PubMed1985

Hemodynamic effects of surface cooling-induced hypothermia on immature pigs with ventricular septal defects.

Clinical interventions for repair of congenital heart defects, such as hypothermia and cardiopulmonary bypass, may cause changes in pulmonary vascular resistance (PVR) and systemic vascular resistance (SVR) leading to deleterious alterations in blood flow. Since the relationship between the pulmonary and systemic circulations in patients with ventricular septal defects (VSDs) is dynamic and susceptible to stimuli, we directly measured hemodynamic variables and blood flow distribution in infant pigs with VSDs during surface cooling. In 12 piglets (aged 4 weeks and weighing 4 kg), VSDs were created by caval occlusion, right ventriculotomy, and septal perforation, resulting in a 2.2 +/- 0.4:1 shunt. SVR and PVR were derived by both the flow probe (FP) and microsphere (microseconds) techniques. Systemic and pulmonary blood flow distribution were measured (microseconds). Qp/Qs ratios were derived by oximetry, FP, and microseconds techniques. Pigs were surface cooled in 28 degrees C while measurements were made at 37 degrees, 32 degrees, and 28 degrees C. SVR increased by FP (4034 +/- 55.4 to 10450 +/- 2132 dynes-sec/cm5 [p less than 0.05]) and by microseconds (3097 +/- 497 to 1022 +/- 2583 dynes-sec/cm5 [p less than 0.05]), while PVR remained unchanged. Qp/Qs ratios increased during hypothermia by FP (2.4 +/- 0.4:1 to 6.3 +/- 1.4:1 [p less than 0.05]), by microseconds (2.2 +/- 0.4:1 to 3.5 +/- 0.8:1 [p less than 0.05]), and by oximetry (1.4 +/- 0.1:1 to 2.6 +/- 0.3:1 [p less than 0.05]). Visceral flow (34.8 +/- 5 to 17.5 +/- 4 ml/100 gm/min [p less than 0.05]) and renal flow (127 +/- 21 to 53 +/- 11 ml/100 gm/min) [p less than 0.05]) both decreased during hypothermia. Systemic surface cooling-induced hypothermia in pigs with VSD causes an increase in SVR but no change in PVR resulting in an increased left to right intracardiac shunt confirmed by three measurement techniques. Redistribution of blood flow favors the lungs while lowering renal and visceral flow. Surface cooling-induced hypothermia and circulatory arrest in infants with VSDs may cause circulatory alterations leading to increased left to right shunt and decreased renal and visceral flow even before cardiopulmonary bypass and intracardiac repair.

Age Factors↗
PubMed1984

Creation of left-to-right shunts in the newborn pig: a new model.

The closer to birth that congenital heart defects are simulated, the more valid the model. Unlike obstructive lesions such as pulmonic and aortic stenosis, which can be constructed in utero or in infancy, left-to-right shunts are more difficult to create due to the extreme friability of fetal and neonatal tissue. A method for creating left-to-right shunts in infant pigs using a pleural-sparing transverse sternotomy and direct side-to-side anastomosis between the redundant pulmonary artery and the ascending aorta has been introduced. The pigs developed palpable thrills, systolic and diastolic flow murmurs, and congestive heart failure. The average pulmonary-to-systemic flow ratio by the microsphere technique was 2.1:1 compared to 2.1:1 by oximetry. Left-to-right shunts can be constructed in infant pigs to simulate congenital heart defects.

Animals↗
PubMed1984

The prognostic value of intraoperative pressure gradients with congenital aortic stenosis.

Patients with congenital aortic stenosis are subject to sudden death without prior symptoms. Indications for operation are based on pressure gradients, but intraoperative evaluation of results after relief of obstruction can be subjective and arbitrary. Between September, 1981, and October, 1983, 21 patients underwent operation for relief of congenital aortic stenosis. Fifteen had valvular, 4 had supravalvular, and 2 had subvalvular stenosis. Seven patients were 1 year of age or younger, 2 being 3 days old. Preoperative inotropic support and emergency operation were necessary in 2 patients. Intraoperative pressure gradients were measured in all but the 2 patients who were 3 days old. All patients survived without complications. Intraoperative and postoperative pressure gradients were available in 16 patients. The average preoperative pressure gradient was 76 mm Hg. It was significantly lowered to 20 mm Hg (p less than 0.001) intraoperatively, which compared with 15 mm Hg postoperatively. Three patients had an unsatisfactorily high intraoperative pressure gradient after initial intervention. Immediate reexploration and incision of the rudimentary commissure in 2 and excision of redundant valvular tissue in the other resulted in a more satisfactory pressure gradient without substantial aortic insufficiency. We suggest that measurement of intraoperative pressure gradients can accurately assess the results of therapy and allow the surgeon the option of reexploration for further intervention. Moreover, the high correlation between intraoperative and postoperative pressure gradients can help in planning postoperative management and future cardiac catheterizations.

Adolescent↗
PubMed1984

Blood flow distribution in infant pigs subjected to surface cooling, deep hypothermia, and circulatory arrest. Deleterious effects in pigs with left-to-right shunts.

Surface cooling, deep hypothermia and circulatory arrest have been used effectively for correction of congenital heart defects in infancy. Which patients are best suited for this technique has not been addressed. The addition of surface cooling to deep hypothermia and circulatory arrest provides homogeneous cooling and avoids swelling due to reperfusion injury after circulatory arrest. However, surface cooling in patients with large left-to-right shunts causes increased peripheral resistance and increased shunting which can result in decreased perfusion of vital organs. The purpose of this study is to measure the effect of a large left-to-right shunt on total organ blood flow distribution in infant piglets during surface cooling, deep hypothermia, and circulatory arrest. Eleven 2-week-old piglets had surface cooling, deep hypothermia, and circulatory arrest for 45 minutes, followed by rewarming and weaning from cardiopulmonary bypass. Microspheres (15 mu) were injected before surface cooling, at 28 degrees C, at 15 degrees C, and after weaning from cardiopulmonary bypass. Group I (five piglets) was the control. Group II (six piglets) had a large (6 mm) left-to-right aortopulmonary shunt established before microsphere injection. Cardiac outputs in both Groups I and II decreased with surface cooling. The distribution of cardiac output in Group I did not change with surface cooling; however, Group II pigs showed marked change in distribution of cardiac output, resulting in decreased renal, visceral, and pulmonary flow (p less than 0.05). Amylase determinations before and after surface cooling, deep hypothermia, and circulatory arrest were unchanged in Group I but elevated in Group II (p less than 0.05). These observations suggest altered cellular metabolism in visceral organs during the period of surface cooling which may be compounded by circulatory arrest and rewarming.

Amylases↗
PubMed1984

Management of tracheobronchial disruption resulting from blunt trauma.

Delayed diagnosis of tracheobronchial disruption resulting from blunt trauma continues to cause major morbidity and death. At the University of Louisville from 1968 to 1982, 13 patients had tracheobronchial disruption resulting from blunt trauma. All injuries were caused by motor vehicle accidents. Disruptions were located in the trachea in six patients and in the right bronchus in seven patients. Physical findings included: subcutaneous emphysema (11 patients), respiratory distress (10 patients), hemoptysis (six patients), and flail chest (four patients). Four patients (30%) died, three from multiple major associated injuries and the other before therapy could be instituted. Among the nine survivors, six had immediate diagnosis and prompt surgical treatment, which consisted of suture repair in five and pneumonectomy in the other patient. Two patients had delay in diagnosis, and repair was attempted at 4 and 30 days, respectively; bronchial stricture resulted in one and pneumonectomy, empyema, and bronchopleural fistula in the other. Another patient with a bronchial mucosal tear was treated nonoperatively without complication. Tracheobronchial disruption should always be considered with massive blunt chest trauma. Repeated bronchoscopy is indicated for unexplained pleural air leaks, lobar atelectasis, or persistent pneumothorax. Prompt diagnosis and expeditious surgical therapy result in fewer complications and increased survival.

Accidents, Traffic↗
PubMed1983

Management of patent ductus arteriosus in the premature infant: indomethacin versus ligation.

A previous report from our institution analyzed the results of pharmacological (indomethacin) closure of patent ductus arteriosus (PDA) in 82 neonates. Closure was achieved in 54 patients. However, gastrointestinal complications occurred in 21, necrotizing enterocolitis in 13, and focal perforation in 8. Overall mortality in the indomethacin group was 40%. This paper compares the results of that pharmacological experience with our subsequent surgical experience with 86 low-birth-weight neonates for whom gestational age, size, illness, and mode of diagnosis were comparable. Mean weight at operation for this study was 1.1 kg; mean gestational age was 29.1 weeks. All infants required endotracheal-assisted ventilation for severe radiographic and clinical hyaline membrane disease. Range-gated Doppler study, retrograde flush aortography, and echocardiographic measurement of the ratio between the left atrium and the aortic root were used to confirm the diagnosis of PDA. Ligation was done in the neonatal intensive care unit using local anesthesia supplemented with morphine. Ventilation was controlled by an inhalation therapist; drug and blood administration were controlled by the infant's nurse. Surgical ligation was employed in all infants except for 7 in whom hemoclip ductal closure was chosen because of extreme instability, coagulopathy, or ductal perforation. There were no operative deaths. Surgical morbidity included ductal perforation (2 patients), wound infection (1), and phrenic nerve injury (1). Necrotizing enterocolitis occurred in 9 patients. The overall mortality was 17%. Patients with preoperative pneumo-thorax had a 32% overall mortality.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Local↗