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Biomedical subjects

E P Todd

Publications and source records attributed to E P Todd.

At least 19 recordsLinked to original sources

Eighteen to 37 hours' preservation of major organs using a new autoperfusion multiorgan preparation.

A new autoperfusion preparation was used to preserve six major organs simultaneously. In 7 Yorkshire white swine, the heart and lungs were separated and removed with the liver, pancreas, duodenum, and both kidneys en bloc while they were self-perfused. Fresh blood, glucose, electrolytes, heparin sodium, methylprednisolone, and a fat emulsion (Soyacal) were infused through the portal vein. No inotropic drugs were necessary. The organs survived for 18 to 37 hours (average survival, 24.6 +/- 2.7 hours [+/- standard error of the mean]). Aortic systolic pressure ranged from 78.5 +/- 5.5 to 98.7 +/- 11.8 mm Hg. Arterial oxygen tension ranged from 206 +/- 23 to 266 +/- 15 mm Hg and arterial carbon dioxide tension, from 20.1 +/- 2.7 to 32.1 +/- 4.9 mm Hg. Blood lactic acid levels decreased from 8.75 +/- 2.06 to 5.50 +/- 2.45 mmol/L at 24 hours. Urine output ranged from 25 to 82 mL/h. Blood urea nitrogen levels decreased from 9.17 +/- 0.59 to 4.67 +/- 1.08 mg/dL. Blood creatinine levels decreased from 1.34 +/- 0.10 to 0.57 +/- 0.22 mg/dL. Serum glutamicoxaloacetic transaminase levels increased from 73.4 +/- 26.3 to 194 +/- 179.5 U/L and serum glutamic-pyruvic transaminase levels, from 44.8 +/- 5.7 to 91 +/- 66.4 U/L. Red blood cell count ranged from 6.94 +/- 0.58 to 13.23 +/- 2.30 x 10(6)/microliters. Lung wet/dry weight ratios changed from 5.79 +/- 0.17 at the beginning to 6.25 +/- 0.16 at 24 hours. The technique for simultaneous multiorgan preservation presented here is simple, effective, and highly reproducible. This study appears to have produced one of the longest average survival times for autoperfusion.

Animals

Ventriculocoronary connections in hypoplastic right heart syndrome: autopsy serial section study of six cases.

Myocardial sinusoids communicating with the coronary systems occur in pulmonary atresia with intact ventricular septum. To test the hypothesis that the extent of ventriculocoronary connections correlates with the degree of right ventricular outflow obstruction as evidenced by clinical, angiographic and gross anatomic findings, a serial section study of six human autopsy hearts representing a spectrum of hypoplastic right heart was undertaken. Slides were evaluated for the presence and extent of ventriculocoronary connections, associated developmental abnormalities and secondary changes in the ventricular walls. Whereas extensive blind-ended deep sinusoids were a feature of all five cases with unrelieved obstruction, ventriculocoronary connections were identified in three. Changes that suggested ongoing remodeling provide new evidence for the postnatal temporal evolution of these anomalous communications. The regional distribution of myofiber disarray in hypoplastic right heart supports the concept that vascularization parallels myocardial organization in the developing human heart.

Coronary Vessels

New autoperfusion preparation for long-term organ preservation.

The problems in long-term organ preservation are ischemia and toxicity from metabolic waste. A simple self-perfusing self-cleaning system has been developed that kept the heart, lungs, and kidney functioning for a mean time of 24 hours. Nine adult dogs were anesthetized and artifically ventilated. The heart and lungs were removed en bloc while being perfused by the heart. One kidney was connected to the descending aorta and inferior vena cava. No anticoagulant was used. Another group of six dogs without functioning kidneys was used as the control group. In the experimental group, urine output ranged from 26 to 48 ml/hr, aortic systolic pressures were 80-107 mm Hg, heart rate was 85-100 beats/min, serum potassium content was 3.25-4.40 mmol/l, and serum sodium content was 155-163 mmol/l. In the experimental group, blood creatinine levels decreased from 0.95 to 0.47 mg/dl during preservation; in the control group, blood creatinine levels decreased from 0.96 to 0.79 mg/dl. Lung biopsies in the preparation with the longest survival showed good preservation for as long as 24 hours, and no thrombi were present. This preparation has the advantage of no ischemic time, no foreign material in the circulation, and the ability to automatically maintain acid-base balance and blood electrolytes. The simplicity of this autoperfusion preparation may allow greater transport distance in organ procurement for subsequent transplantation.

Animals

A simple technique for multiorgan preservation.

A simple technique for multiorgan preservation with no ischemic time was developed. In five mongrel dogs, the heart and lungs were separated and removed with the liver, pancreas, kidneys, and a small portion of intestine en bloc while they were being self-perfused. A respirator was used for oxygenation. Arterial and venous blood pressures were measured by indwelling catheters. Fresh blood, glucose, electrolytes, mannitol, prednisolone, and a fat emulsion (Soyacal) were infused through the portal vein. The organs were experimentally perfused for 12 hours. Aortic systolic pressure ranged from 75 to 125 mm Hg, central venous pressure from 0 to 5 mm Hg, portal venous pressure from 0 to 3 mm Hg, bile output from 5 to 20 ml/hr, urine output from 10 to 70 ml/hr, and hematocrit value from 35% to 55%. The heart and lungs were normal and physiologically functional during the preservation time. The pancreas and small intestine appeared normal. Three of the livers showed some congestion. The kidney in one organ block appeared to have some edematous swelling after 16 hours. The technique for multiorgan preservation presented here is simple and effective. The preliminary data are encouraging and suggest further evaluation.

Animals

Down's syndrome.

We discuss the ethical, psychosocial, economic, and medical dimensions of the treatment and management of a child with Down's syndrome and a congenital heart defect.

Down Syndrome

The effect of supine rotation on left ventricular dimensions in man: a study using radio-opaque epicardial markers.

It has been reported that patient rotation into the left lateral decubitus position (30 degrees rao) produces significant changes in the regression equations used for left ventricular volume determination and that normal values for echocardiographic left ventricular dimensions obtained from supine patients differ from those obtained after rotation. The purpose of this study was to establish whether patient rotation is associated with changes in left ventricular size and systolic function. The distances between left ventricular epicardial markers attached at the time of cardiac surgery were measured using biplane cineradiography in 14 patients in order to determine left ventricular dimensions before and after rotation. Supine epicardial left ventricular dimensions were not significantly different from those obtained with the patient rotated 30 degrees rao. These results suggest that reported changes in invasive and noninvasive measurements of left ventricular function associated with patient rotation are not primarily due to changes in left ventricular size.

Adult

Effects of hypothermia on propranolol kinetics.

Propranolol may be uniquely useful in cardiac surgical procedures, since beta adrenergic blockade can prevent the hypokalemia and associated arrhythmias which result from systemic hypothermia. To determine the effects of hypothermic cardiopulmonary bypass (HCPB) on the in vivo handling of propranolol, serial drug plasma concentrations (Cp) were measured during HCPB in 12 patients who had been treated chronically with propranolol prior to surgery. Although no further propranolol was given during the procedure, Cp values (corrected for plasma volume dilution) were higher during hypothermia than in the preoperative period, falling to or below control levels after rewarming. Due to the variables inherent in patient surgery, meaningful kinetic analysis could not be carried out. Therefore, intravenous propranolol (1 mg/kg) was given twice to each of 5 dogs, first after anesthesia only, then after anesthesia and systemic cooling to 26 degrees in a water bath Cp values measured serially over 2 hr after drug administration were consistently higher during hypothermia. Compared with the paired normothermic control studies, hypothermia markedly reduced the apparent volume of distribution (6.78 +/- 1.65 vs 2.08 +/- 0.58 L/kg; p less than 0.001) and the total body clearance of propranolol (64.4 +/- 11.0 vs 32.3 +/- 7.2 ml/kg/min; p less than 0.005). These data show that hypothermia substantially alters the pharmacokinetics of propranolol, resulting in plasma drug levels higher than those predicted from kinetic patterns derived under normothermic conditions.

Adult

The role of thymectomy in red cell aplasia.

Red cell aplasia is an unusual cause of anemia. Fifty percent of all patients with red cell aplasia will have a thymoma. Twenty-five to 30% of those who undergo thymectomy will be cured. Data are presented that suggest that any patient with red cell aplasia should have thymectomy through a median sternotomy. One of 3 such patients who underwent the operation has had complete remission for two years.

Aged

Structure-related thrombosis involving a porcine xenograft valve.

A patient developed acute congestive heart failure following chordal rupture and underwent mitral valve replacement with a porcine xenograft. He recovered adequate hemodynamic function but died one month later with widespread bronchopneumonia. Postmortem examination revealed a prominent muscular shelf in the right coronary leaflet of the xenograft, and focal thrombosis involving the adjacent sewing ring and left atrial wall. The location of the thrombus suggests that it formed as a result of local stasis behind the large muscular shelf. Limiting the size of this muscular shelf by valve selection and construction may reduce the thrombogenicity of this prosthesis.

Bioprosthesis

Repair of chest wall defects with prosthetic material.

This report summarizes our experience during a four-year period with the repair of 8 thoracic cage and 3 diaphragmatic defects requiring reinforcement with prosthetic material. Defects as large as the entire left hemidiaphragm or the right anterior chest wall including ribs two through six from the midsternum to the midaxillary line were adequately repaired. The technical approach utilized to obtain a secure, nonmobile thoracic cage involved the placement of sutures through drill holes or around ribs, rather than through the periosteum or pericostal soft tissues. Successful diaphragmatic repair was dependent on proper anchoring of the medial border of the prosthesis, placing sutures in the pericardium as necessary. Skin coverage for thoracic cage defects was achieved with widely undermined and advanced local tissue or previously delayed pedicle flaps. All patients had good evidence of chest wall stabilization after operation, and all were removed from mechanical ventilation within three days. One patient died of myocardial infarction twenty days after operation, and a second patient died later of metastatic disease. On the basis of our experience, we conclude that the range of chest wall lesions that can be surgically corrected or palliated is increased by the use of prosthetics implanted with techniques described here.

Adult

Studies of experimental cervical spinal cord transection. Part III: Effects of acute cervical spinal cord transection on cerebral blood flow.

Regional cerebral blood flow (CBF) was measured by the microsphere technique in anesthetized, mechanically ventilated dogs before and after cervical laminectomy in four (control group), or cervical laminectomy followed by cervical cord transection (CCT) at the C-6 level in six (experimental group). No significant differences in arterial pH, pO2 or pCO2 were observed between control and experimental dogs. Baseline values for mean arterial pressure (MAP) were also similar in the two groups, but MAP fell in all experimental dogs after CCT (p less than 0.025). At 120 minutes after CCT, three of the six dogs had an MAP greater than 60 torr (66 +/- 4 torr), and in three the MAP was greater than 50 torr (45 +/- 3 torr). Regional CBF in cortical gray matter, white matter, and medulla did not change significantly after CCT in dogs with MAP greater than 60 torr. The CBF fell significantly at 120 minutes after CCT in all regions sampled in the dogs with MAP less than 50 torr (p less than 0.025). At 30 and 120 minutes after CCT, cerebellar blood flow fell significantly in all experimental animals (p less than 0.05). These findings indicate that, despite hypotension and sympathetic denervation of cerebral vessels, CBF in cortical gray matter, white matter, and medulla is maintained at normal levels after CCT by autoregulation as long as MAP exceeds 60 torr. Decreased cerebellar blood flow in the experimental group suggests redistribution of CBF after CCT with relative preservation of flow to gray matter, white matter, and medulla. Reduced CBF in the acutely cord-injured patient with significant hypotension (MAP less than 60 torr) may stimulate or complicate coexistent head injury.

Animals

Late isolated left ventricular tamponade. Clinical, hemodynamic, and echocardiographic manifestations of a previously unreported postoperative complication.

A unique case of late postoperative left ventricular tamponade, hemodynamically indistinguishable from severe left ventricular failure, is reported in a patient 1 month after an apparently uncomplicated aortic valve replacement. An echo-free space behind the left ventricle led to surgical exploration and successful resolution of the disease process. To our knowledge, this is the first documented case of isolated left ventricular tamponade in the literature. The findings highlight the importance of postoperative echocardiography in the evaluation of the patient having cardiac surgery.

Aneurysm, Infected

Acute traumatic hemothorax.

Over the past 5 years, 107 patients have been evaluated for acute traumatic hemothorax at the University of Kentucky Medical Center. Immediate tube thoracostomy was performed on 90 patients for evacuation of blood and air. Only 2 patients died. Thoracotomy was performed as part of the initial therapy in 9 patients. Thoracotomy for continued hemorrhage from a pulmonary parenchymal injury was required in 3 patients from the entire group. Thoracentesis or observation was the initial therapy for limited hemothorax in 8 stable patients. Three of these patients subsequently required tube thoracostomy 2 to 23 days following injury due to expanding effusions, and 1 patient required multiple thoracotomies for sepsis, fibrothorax, and empyema. These observations indicate that early evacuation of blood by means of a tube thoracostomy is essential to minimize morbidity in acute traumatic hemothorax. If continuing hemorrhage after tube thoracostomy occurs, there is a higher association of injury to additional vital structures.

Abdominal Injuries

Results and patterns of perioperative myocardial infarction.

Myocardial injury during a variety of cardiac surgical operations was determined in 57 patients by serial electrocardiograms (ECG's), serial determinations of serum creatine phosphokinase (CPK), and perioperative and postoperative technetium-99m stannous pyrophosphate (PYP) scans. ECG evidence of injury developed in four patients, whereas positive localized injury by PYP scan developed in ten. Twenty-one patients had elevated CPK enzymes postoperatively. The localization of injury by PYP scan correlated with ECG evidence of infarction in only one of four patients. Localized left ventricular injury by PYP scan without new Q waves on the ECG was common (5/12) in patients undergoing aortic valve replacement with perfusion of the coronary arteries. The injury in patients with congenital heart disease occurred at sites of ventricular incision or suggested possible air embolization of the coronary arteries. Perioperative infarction is frequently segmental and nontransmural and occurs in patients with coronary, valvular, and congenital heart disease.

Adult

Giant tracheoesophageal fistula: management by esophageal diversion.

Giant tracheoesophageal fistulas complicating the management of respiratory insufficiency are often difficult to close successfully because of suture line tension and narrowing of the trachea or esophagus or both. Recovery of lung function often depends on successful diversion of gastrointestinal contents from the tracheobrachial tree. We have managed six patients with giant tracheoesophageal fistula. In three cases the lesions were related to overinflation of low-pressure balloon cuffs. The only survivors were two of three patients managed by esophageal diversion and reconstruction through extrathoracic incisions. The techniques, advantages, and disadvantages of esophageal diversion for giant tracheoesophageal fistula are presented.

Esophagus