Starling resistor vs. distensible vessel models for embolic pulmonary hypertension.

We investigated whether the Starling resistor model (Mitzner et al. J. Appl. Physiol. 51: 1065-1071, 1981) or a distensible vessel model (Haworth et al. J. Appl. Physiol. 70: 15-26, 1991) best describes pulmonary vascular pressure-flow (Q) relationships in embolic pulmonary hypertension. Mean pulmonary arterial pressure (Ppa)-Q plots at constant left atrial pressure (Pla) and Ppa-Pla plots at constant Q were investigated in seven dogs before and after 500-micron glass bead pulmonary embolism. Embolization to a mean angiographic obstruction of 78% increased the slope and extrapolated pressure intercept (P(i)) of Ppa-Q plots and increased the inflection point of Ppa-Pla plots, above which an increase in Pla is transmitted to Ppa in a ratio of approximately 1:1. The Starling resistor and the distensible vessel model provided a reasonably good fit to the Ppa-Q and Ppa-Pla coordinates before and after embolism. However, contrary to the prediction of the Starling resistor model, no correlation was found between the inflection point of Ppa-Pla plots and P(i). We therefore conclude that an increased closing pressure is unlikely to contribute to embolic pulmonary hypertension.

[Aspects of pathological physiology of the dog in extracorporeal circulation]. / Aspects de la physiologie pathologique du chien en circulation extra-corporelle.

During ECC, dogs ventilate spontaneously according to classical physiology. Further, given the CO2 clearance insured by the ECC oxygenator, many hours of reversible apnea are tolerated without sequellae. Surgical removal of the lungs shows that an emptied chest still responds to chemical drives, but the absent lung-recoil causes hyperinflation with lethal failure. Finally, liquid ventilation induces metabolic acidemia through phasic gut ischemia and respiratory muscle strain that destroys the delicate lung structure.

Postoperative radiotherapy after pneumonectomy: impact of modern treatment facilities.

PURPOSE: The present study was undertaken to see how modern treatment facilities, computed tomography (CT)-based treatment planning and linear accelerator, have modified the results of postoperative irradiation after a pneumonectomy for lung cancer. METHODS AND MATERIALS: Between 1970-1985, 103 patients were treated in our department after a pneumonectomy: 50 patients with a T1T2N0 tumor and 53 patients with a T3, N1 or N2 tumor. Three groups were considered: 27 patients had only surgical resection, 51 patients were irradiated postoperatively with a Co60 source, and 25 patients were treated using those modern facilities. RESULTS: The 5-year survival varies from 4% to 31% according to the tumor extent but also to the radiation technique. Patients treated with a Co60 source had a dismal 5-year survival rate (8%) whereas patients treated with the modern facilities had a 5-year survival rate of 30% similar to the 31% of the control surgical group including less advanced tumors. CONCLUSION: Linear accelerator and computed tomography-based treatment planning improved the accuracy of postoperative thoracic irradiation and allow to deliver high doses to the mediastinum even after a pneumonectomy.

Embolus size affects gas exchange in canine autologous blood clot pulmonary embolism.

Embolic pulmonary hypertension is associated with alterations in gas exchange of variable severity, which we hypothesized to be related to embolus size. We therefore examined the effects of different-size autologous blood clot embolization on pulmonary arterial pressure-cardiac output relationships (Ppa/Q) and on the distribution of ventilation-perfusion ratios (VA/Q) in 18 intact anesthetized and ventilated (inspired fraction of O2 0.4) dogs. Multipoint Ppa/Q plots were generated by a manipulation of venous return before and 60 min after sufficient amounts of small (1 mm, n = 6 dogs), medium (5 mm, n = 6 dogs), or large (10 mm, n = 6 dogs) clots to increase Ppa to 50 mmHg. The distribution of VA/Q was determined by the multiple inert gas elimination technique at the same intermediate Q in each of these experimental conditions. All three sizes of emboli resulted in an 82-92% mean angiographic pulmonary vascular obstruction and increased both the extrapolated pressure intercepts and the slopes of the linear Ppa/Q plots. Gas exchange was altered the most after large clots, which were associated with lower arterial pH, higher physiological and inert gas dead spaces, higher dispersion of ventilation, and also lower mean VA/Q of perfusion distributions. In contrast, inert gas dead space was decreased after small clots. We conclude that, in autologous blood clot embolic pulmonary hypertension, Ppa/Q characteristics are unaffected by embolus size but that gas exchange is affected differently, mainly in high-VA/Q regions and most often after the largest clots.

[Treatment of breastplate deformities: assessment using CT scanning and functional tests]. / Cures des malformations du plastron sternal: évaluations par CT-scan et épreuves fonctionnelles.

A study to evaluate both the pre- en postoperative functional and morphologic status of major anterior chest wall deformities. Four of the eight patients suffered from a progressive reduction in physical capabilities. Preoperative pulmonary function tests demonstrated restriction in pulmonary function. In the postoperative period there was progressive return to normal physical strength without objective improvement in pulmonary function. Pre- and postoperative thoracometric study by CT scan allowed us to evaluate the morphologic changes. Two patients with pectus excavatum (funnel chest) demonstrated not only a right-left asymmetry but also A-P compression of the heart without displacement to the left. We consider this to be one of the causes of functional impairment and an absolute indication for corrective surgery.

Effects of embolus size on hemodynamics and gas exchange in canine embolic pulmonary hypertension.

We examined the effects of different-sized glass-bead embolization on pulmonary hemodynamics and gas exchange in 12 intact anesthetized dogs. Pulmonary hemodynamics were evaluated by multipoint pulmonary arterial pressure (Ppa)/cardiac output (Q) plots before and 60 min after sufficient amounts of 100-microns (n = 6 dogs) or 1,000-microns (n = 6 dogs) glass beads to triple baseline Ppa were given and again 20 min after 5 mg/kg hydralazine in all the animals. Gas exchange was assessed using the multiple inert gas elimination technique in each of these experimental conditions. Embolization increased both the extrapolated pressure intercepts (by 6 mmHg) and the slopes (by 5 mmHg.l-1.min.m2) of the linear Ppa/Q plots, together with an 80% angiographic pulmonary vascular obstruction. These changes were not significantly different in the two subgroups of dogs. However, arterial PO2 was most decreased after the 100-microns beads, and arterial PCO2 was most increased after the 1,000-microns beads. Both bead sizes deteriorated the distribution of ventilation (VA)/perfusion (Q) ratios, with development of lung units with higher as well as with lower than normal VA/Q. Only 100-microns beads generated a shunt. Only 1,000-microns beads generated a high VA/Q mode and increased inert gas dead space. Hydralazine increased the shunt and decreased the slope of the Ppa/Q plots after 100-microns beads and had no effect after 1,000-microns beads. We conclude that in embolic pulmonary hypertension, Ppa/Q characteristics are unaffected by embolus size up to 1,000 microns.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchiolar morphology after systemic arterial interruption.

To assess ischemic lesions as a factor in obliterative bronchiolitis after lung transplantation, the authors severed the left bronchial arteries of 15 dogs, together with the left stem bronchus, the latter being immediately reanostomosed. They examined the bronchioles at weekly interfals up to three and a half months. On the week chosen each dog was anesthetized, totally heparinized, and exsanguino-perfused with saline. Just after heart arrest, the thoracic aorta was injected with a barium solution until this white medium appeared in the bronchial arteries. The heart-lung blocs were excised en bloc, submitted to soft-tissue x ray, fixed, and then sliced to 1 cm. Corresponding right and left 5-mm-thick samples of these slices were prepared for contact microradiography followed by histologic 5-to-20-micron-thick, stained, correlated specimens. For two weeks the left bronchial arteries remained empty, but there was no necrosis or edema. Between two and four weeks barium solution appeared in the bronchial arteries, and the bronchiolar epithelium had become multistratified. Later the left bronchiangiogram became similar to the right, but there were more folds of the mucosa and a little submucosal fibrosis. These studies provide proof that no significant ischemic lesions occurred during repermeation of the bronchiolar vascular bed. Ischemia, if existent, is not a significant factor in obliterative bronchiolitis.

Effort rupture of the diaphragm.

Effort rupture of the diaphragm is rare and accounts for only 1% of all diaphragmatic injuries. A 23 year old patient with bilateral rupture that followed sudden movement is described.

Penetration of aminoglycosides in uninfected pleural exudates and in pleural empyemas.

The concentrations of gentamicin, netilmicin, and amikacin were determined after one single intravenous injection in uninfected pleural fluid after thoracotomy and in purulent pleural empyemas. The mean peak concentrations in the pleural fluid after the injection of gentamicin (1.5 mg/kg), netilmicin (2.0 mg/kg), and amikacin (7.5 mg/kg) were 2.9 +/- 0.3 mg/L, 3.7 +/- 0.8 mg/L, and 11.0 +/- 3.1 mg/L, respectively. The pleural penetration of the drugs was very high (from 80.0 to 99.1 percent). By contrast, gentamicin and netilmicin were not detectable in empyema pus; in this exudate the mean peak level of amikacin was 5.7 +/- 2.2 mg/L, with the penetration of this drug being 31.0 percent. The concentrations of parenterally administered aminoglycosides are substantially lower in empyema pus than in sterile pleural fluid. The possibility of poor pleural penetration of some aminoglycosides, as well as the presence of local conditions in pleural empyema unfavorable to the bioactivity of these drugs, must be kept in mind when treating pleural infections.

Cardiac tamponade following penetrating thoracic trauma: unusual evolution.

We report a case of cardiac tamponade following a penetrating wound of the heart treated surgically. The patient developed later on a pericarditis of the immunologic type complicated by new tamponade. The clinical situation was only relieved by corticotherapy.

Hypophosphatemia after cardiothoracic surgery.

The incidence of hypophosphatemia during the first 48 h following cardiothoracic surgery was prospectively studied in 74 patients. Hypophosphatemia, defined by a serum phosphate below 2.50 mg/dl, was observed in 19 of 34 (56%) patients after thoracic surgery and in 20 of 40 (50%) patients after cardiac surgery. As a whole, hypophosphatemia occurred earlier after thoracic than after cardiac surgery. After thoracic surgery, hypophosphatemia was milder for patients in whom bleeding was more severe. The anticoagulant solution CPD used in stored blood was identified as an important source of phosphate. These results indicate hypophosphatemia is a common finding after cardiothoracic surgery. Since severe hypophosphatemia can be related to phosphate depletion, phosphate supplements could be warranted especially during thoracic surgery when blood transfusions are less than 1000 ml.

[Significance of cardiopulmonary resuscitation in thoracic surgery]. / Intérêt de la ressuscitation cardiopulmonaire en chirurgie thoracique.

45 patients admitted in the thoracic non-cardiac surgery service of the U.L.B. between 1966 and 1983 (17 yrs) were short- or longterm survivors of cardiopulmonary resuscitation. In november 1979 the traditional system was supplanted by a mobile unit with reduction of the interval between cardiopulmonary arrest and resuscitation to 1 minute. The obtained results are as follows: A mobile thoracic wall or intra-thoracic visceral lesions or displacement of thoracic content secondary to a recent thoracic intervention or serious injury do not constitute a contra-indication. Closed chest massage was mainly applied. Displacement of the heart secondary to chronic tuberculosis or pneumonectomy or serious thoracic injury are not formal contra-indications. Open cardiac massage was applied during surgical interventions or with hypovolemic shock secondary to massive intra-thoracic hemorrhage or cardiac tamponade. Pulmonary resuscitation with extra-corporeal circulation was only applied when mechanical ventilation did not suffice. All patients succumbed due to an associated lung involvement with destruction of the pulmonary parenchyma. The use of a mobile unit increased the number of successful resuscitations but did not change at all the duration of survival of the patients nor the number of neurological deficits. The survival time was only affected by 2 factors; the primary disease for which the patient was hospitalized and the presumed cause of arrest. All the other factors had no influence on the duration of survival; a. type of intervention; b. place of C.P. arrest and c. method of resuscitation.