8:30 A.M. Scientific Session

Ballroom

29. Mediastinal Masses in Infants and Children

WILLIAM J. POKORNY,* and JOSEPH O. SHERMAN,*

Chicago, Illinois

Sponsored by F. S. Idriss, Chicago, Illinois

During the last 18 years, 111 infants and children under 16 years of age were admitted to the Children’s Memorial Hospital with a mediastinal mass. There were 36 neurogenic tumors, 3 enteric duplications, 11 bronchogenic cysts, 9 primary mediastinal Hodgkin’s Disease, 15 lymphosarcomas, 6 undifferentiated sarcomas, 7 lymphangiomatous malformations, 4 teratomas, 3 thymic tumors, 3 thymic cysts, 7 thymic hyperplasias, 4 inflammatory masses and 3 miscellaneous tumors. 54% were malignant.

This retrospective study reviews the presenting signs and symptoms as well as laboratory and radiographic findings in an effort to outline useful points in the differential diagnosis. Treatment and follow-up are presented with particular emphasis on the 27 malignant neurogenic tumors and the 34 sarcomas and lymphomas presenting primarily as mediastinal masses.

Fifty of the 51 children with benign tumors were alive and well at the last follow-up. Thirty of the 61 children with malignant tumors died, including the 15 children with lymphosarcomas and the 5 children over 2 ½ years of age with neuroblastoma. There was only one death in the group of 13 children under 13 months of age with neuroblastoma. All 9 children with ganglioneuroblastoma, regardless of age, were living and well at the last follow-up.

30. Surgical Treatment in Myasthenia Gravis: A 27 Year Experience

HERBERT E. COHN,* ROBERT W. SOLIT,* NATHAN

SCHLEZINGER,* and NORMAN J. SCHATZ,*

Philadelphia, Pa.

Sponsored by Charles Fineberg, Philadelphia, Pa.

Surgical removal of the thymus gland now assumes an important role in the treatment of myasthenia gravis at our institution. Although the disease is characterized by spontaneous remissions and exacerbations, and symptoms may be controlled with anticholinesterase drugs, medical therapy generally does not effect a cure. Thymectomy can result in complete and permanent remission in properly selected cases. Increasing experience has been gained in the surgical approach to this disease, results have become more predictable, and postoperative morbidity and mortality has been significantly reduced.

Since 1946, 56 patients have undergone thymectomy for myasthenia gravis at the Thomas Jefferson University Hospital. Sixteen patients had thymomas. The patients have ranged in age from three years to 70 years, with the average age in the thymoma group being 50 years, and that in the non-thymoma group being 28 years.

Prior to 1962, there were five postoperative deaths in 18 patients. All of these deaths were related to ventilatory complications. Since 1962 there have been two postoperative deaths in 37 patients, both in patients with malignant thymomas and unrelated to ventilatory complications. There have been no deaths in the non-thymoma group. Of the 49 patients surviving operation, 43 have shown definite improvement with 18 showing complete remission to this time, anywhere from two to 11 years.

Although the etiology of the disease remains obscure, refinements in case selection and interoperative and postoperative management has led to a satisfactory outcome in the greater majority of these patients. Our experience compares favorably with that of other institutions caring for patients with similar problems. Indications for operation and pre- and postoperative management are reviewed. Correlation of clinical results with pathologic findings is presented, and the pertinent literature is reviewed. Our experience suggests that thymectomy is the preferred method of treatment in those cases of myasthenia gravis that do not show a favorable response to medical therapy.

31. Cardiorrhaphy in the Emergency Center

KENNETH L. MATTOX,* ARTHUR C. BEALL, JR.,

GEORGE L. JORDAN, JR.,* and MICHAEL E. DeBAKEY, Houston, Texas

The acutely injured patient may require emergency thoracotomy as an integral part of his resuscitation. In critical circumstances thoracotomy in the emergency center for control of hemorrhage, cardiac massage, and direct repair of crucial injuries can be lifesaving. Such an approach may be required for urgent repair of cardiac injuries.

Between January of 1970 and December of 1972, over 5000 emergency operations were performed for blunt and penetrating trauma at Ben Taub General Hospital. Emergency thoracotomy was required in more than 300 cases. Of these, 106 patients required thoracotomy in the emergency center due to rapid deterioration in their clinical condition. Twenty-nine of these patients who required such a maneuver had injury to the heart.

This aggressive approach allowed salvage of 69 per cent of these critical patients with cardiac injuries. Autotransfusion, emergency cardiopulmonary bypass and fine screen filtration of transfused blood have been valuable adjuncts to this lifesaving measure. Thoracotomy in the emergency center should be considered as a primary modality in the management of moribund patients with penetrating wounds of the chest.

32. Effect of Neural and Humoral Factors on Pulmonary Hemodynamics and Microcirculation in Pulmonary Embolism

I. AYHAN OZDEMIR,* WATTS R. WEBB, and STENNIS D. WAX,*

Syracuse, N.Y.

Clotted blood releases humoral substances including serotonin which deleteriously alter cardiopulmonary hemodynamics much as occurs in pulmonary embolism. The etiology and role of the neural or humoral factors have not been established.

Thirty-one anesthetized dogs were divided into five groups. Effects of autologous clot 2 ml/kg, serotonin 75 micrograms/kg/min, heparin 10 mg/kg and reserpine 0.2 mg/kg x 3, on intact and denervated (reimplanted) left lungs were studied by measuring cardiac output (CO), right a trial (RA), pulmonary artery (PA), pulmonary artery wedge (PAW), pulmonary venous wedge (PVW), small pulmonary vein (SPV), left atrial (LA) and systemic pressures. Pulmonary and systemic vascular resistances were calculated. Pulmonary microcirculation was studied with cinemicroscopy up to 450 magnification.

In intact lung with serotonin infusion or autologous clot injection PA and PVW pressures increased 120% (p <0.02). PAW and SPV pressures rose minimally as LA pressure fell. Thus pulmonary vascular resistance increased primarily in the arterioles. Cardiac output decreased 25-35%, systemic pressure fell and systemic vascular resistance decreased 26% (P <0.05). Pulmonary microcirculation was severely decreased and showed extensive red cell aggregation.

Lung denervation did not prevent serotonin or autologous clot induced pulmonary vascular hypertension and microcirculatory changes. Heparinized dogs tolerated 150% more clot than controls, pulmonary vascular hypertension was significantly less and cell aggregation did not occur in the microcirculation. In dogs pretreated with reserpine, autologous clot or serotonin induced pulmonary vascular changes were prevented and capillary microcirculation remained essentially normal.

These studies suggest that serotonin from autologous clot causes further cell aggregation and microemboli in the pulmonary bed which can be protected by heparin and by reserpine which depletes the blood serotonin level. Humoral factors play a more significant role than neural factors in the progressive patho-physiology of pulmonary embolism (increased pulmonary vascular resistance, interstitial and intra-alveolar edema, atelectasis). Motion pictures of the micro-circulation will be shown.

33. Prognostic Factors in the Treatment of Acute Respiratory Insufficiency with Long-Term Extracorporeal Circulation

J. DONALD HILL,* JACK RATLIFF,* ROBERT FALLAT,*

HARVEY TUCKER,* MAURICE LAMY,* HARM DIETRICH,*

and FRANK GERBODE, San Francisco, Calif.

The lungs, inflicted with acute pathological changes producing severe hypoxemia, can recover if given time. Based on this premise, 21 patients were treated with prolonged extracorporeal oxygenation to provide the lungs time to heal. Eleven of the 21 patients were successfully taken off perfusion. Four were ultimate survivors. All pathological forms of acute respiratory insufficiency therefore are not reversible. The identification of various prognostic factors are important if this new therapy is going to be properly applied. To expand this identification process we performed open lung biopsies for pathological classification and graphed daily measurements of Pa02, compliance, PVR, cardiac output, Qs/Qt and VD/VT at variable FI02 and PEEP enabling us to develop pulmonary function profiles.

The following factors seem to be important in determining the reversibility of the pulmonary lesion:

1. The shorter the time lapse from onset of disease to initiation of perfusion, the more likely the lungs will improve during perfusion.

2. The presence of exudate and inflammatory cells in the pre-perfusion lung biopsy are more favorable for reversibility than fibroblastic infiltration.

3. Pulmonary insufficiency resulting from trauma is a favorable etiology.

4. Hypoxia related to severe ventilation-perfusion inequality (V/Q) is a favorable form of reversible pulmonary pathology.

5. Hypoxemia related to Qs/Qt (fixed shunt or severe diffusion abnormality) is an unfavorable form of pulmonary damage.

6.        Maintaining high pulmonary artery blood saturation and adequate flow was associated with unusual improvements in pulmonary recovery.

34. Prolonged Extracorporeal Cardiopulmonary Support in Man

ROBERT H. BARTLETT,* ALAN B. GAZZANIGA,* SUSIE W. FONG,*

NORA E. BURNS,* TAMAR GERAGHTY,* NANCY WETMORE,*

DOUG WILL,* GILLIAN WILLIAMS,* and

CHRISTINE WOLDANSKY,* Irvine, Calif.

Sponsored by John E. Connolly, Irvine, Calif.

Techniques for management of prolonged extracorporeal circulation (ECC), and characterization of the normal response to that procedure, have been studied in sheep in our laboratory for 4 years. Based on this experience, prolonged ECC (>24 hours) has been carried out in 4 patients for periods of 2, 3, 3, and 16 days. Venoarterial bypass (60-90% of cardiac output) was used with: a membrane oxygenator circuit with no reservoirs, low dose heparin continuously titrated against clotting time, and servo-regulated bypass flow based on arterial and pulmonary arterial pulse contour. Hemodynamics, oxygen delivery and consumption, blood damage, organ function and damage, oxygenator function, and detailed studies of coagulation and platelet function were measured at regular intervals. One 2 year old boy was supported for 2 days for cardiac insufficiency; he survived without difficulty. Three young adults were supported for severe pulmonary insufficiency; all died with irreversible lung damage. ECC proceeded without incident in all patients. Coagulation factors remained normal while platelet function and concentration decreased slowly during bypass. Kidney, brain, liver and heart function remained normal up to 16 days. Mean pulmonary artery pressure could be maintained below 10mm Hg resulting in the resolution of interstitial infiltrates of adult respiratory insufficiency. Irreversible lung damage was manifested by very high pulmonary vascular resistance and very little gas exchange. Prolonged ECC can be carried out without complications for more than 2 weeks. Further clinical experience is needed to improve criteria for patient selection and timing of this procedure.

35. Impaired Oxygenation at Clinical Levels of Humidity: A Laboratory Study

NATHANIEL P. H. CHING,* JOSEPH M. KAZIGO,*

HAROLD Z. SCHEINMAN,* ROBERT G. HICKS,* and

THOMAS F. NEALON, JR., New York, N.Y.

In a laboratory study of oxygen toxicity, humidity levels used in current clinical practice proved undesirable based on lower blood oxygen determinations. The effect of different levels of oxygen on individual lungs as measured by blood PO₂ levels was studied in dogs ventilated with a trachea! divider. One lung was ventilated with room air while the other was ventilated with 100% oxygen. Humidity of the gases ranged from dry to 50 mg/L of water. Humidity was supplied by an Engstrom ultrasonic nebulizer (17-50 mg/L) or by heating Bennet humidifiers to 24°C (11-15 mg/L) or 40°C (20-41 mg/L). Blood was sampled from the pulmonary veins after 30 minutes, 5 and 7 hours and hourly from the femoral artery for analysis of pH, PCO₂ and PO₂. After 7 hours the ventilating mixtures were reversed and pulmonary vein blood was again sampled for analysis of pH, PCO₂andPO₂.

After prolonged ventilation the lungs ventilated by the high oxygen mixtures produced gradually decreasing PO₂’s. When the mixtures between the two lungs were reversed the high oxygen mixture again produced high PO₂’s when introduced into the contralateral lung for the first time. The diminution in oxygenation which was measured after prolonged ventilation with high concentrations of oxygen was most severe for water contents of 28-50 mg/L. This water content is the same as that produced by the most commonly used clinical apparatus. Additional studies aimed at delineating this mechanism will be presented.

36. Positive-Pressure Breathing Treatments in Postoperative Respiratory Therapy: Myth vs. Fact

DOUGLAS H. McCONNELL,* GERALD D. BUCKBERG,*

and JAMES V. MALONEY, JR., Los Angeles, Calif.

Intermittent positive pressure breathing treatments (IPPB) are an accepted adjunct for pulmonary toilet in the postoperative thoracic surgical patient. The rationale for IPPB is that it (1) expands unventilated alveoli, (2) dilates collapsed bronchi, (3) increases tidal volume, and (4) aids the elimination of secretions. It is fundamental to this rationale that pulmonary expansion by positive pressure applied to the upper airway is different and superior in physiologic effect to pulmonary expansion created by the negative pleural pressure of normal inspiratory effort. It is the purpose of this study to present data which proves false this widely accepted premise. Objective evidence demonstrates: 1) the physical force expanding the lung in normal respiration is atmospheric pressure (not negative pleural pressure) and is identical to the physical effects of IPPB, 2) bronchial dilation achieved with IPPB is the same as with normal inspiration (Otis-Proctor method), 3) significantly increased alveolar expansion can be achieved with continuous positive pressure breathing (CPPB or PEEP), by voluntary effort, or by breathing through a restricted orifice without positive pressure, but is not achieved by conventional IPPB treatments, 4) the direct pulmonary effects of a normal inspiration and positive pressure inspiration of the same depth and at the same thoracic volume are identical, 5) that the only physiologic difference between a normal and positive pressure inspiration of the same depth and at the same thoracic volume is related to the circulation. An appropriate understanding of the physiology of respiratory mechanics enables one to achieve the benefits that are erroneously attributed to IPPB without the cost and inconvenience associated with it.

* By Invitation