Open lung biopsy in patients with diffuse pulmonary infiltrates and acute respiratory failure.

Patients with diffuse pulmonary infiltrates and acute respiratory failure (ARF) potentially can benefit from diagnostic information provided by open lung biopsy (OLB). To better quantify possible benefits and risks, we reviewed an 11-yr experience with 80 such patients. Although OLB did provide a specific etiologic diagnosis in 53 patients (66%) and did influence therapy in 56 patients (70%), only 24 patients (30%) survived to hospital discharge, and 9 patients (11%) survived for 1 yr or more. Survival rates did not depend on the availability of a specific diagnosis, changes in diagnosis, or changes in therapy. Survival was improved in younger patients and patients not requiring preoperative mechanical ventilation. Fifteen patients (19%) suffered complications possibly related to OLB; the survival rate to discharge was decreased in these patients, although not significantly. We conclude that OLB provides a specific etiologic diagnosis in many patients with diffuse pulmonary infiltrates and ARF, but that its utility in these patients is limited by current shortcomings of therapy.

Intrathoracic lymphangioma.

Of 14 cases of intrathoracic lymphangioma, 4 occurred in the anterior, 5 in the superior, and 4 in the posterior mediastinum. One lesion was diffuse and associated with disappearing bone disease (Gorham's disease). The anterior mediastinal lymphangiomas occurred in adults and seemed to arise from the mediastinum. They could not be distinguished from other anterior mediastinal lesions on plain film roentgenograms. The lesions of the superior mediastinum were extensions from cystic hygromas of the neck and occurred primarily in children. Recurrence was common because complete resection was not possible. Computed tomography was helpful in detecting the cervical extension and cystic nature of these lesions. Although two of the four posterior compartment lesions were isolated lymphangiomas, the other two were part of a much more extensive and generalized lymphangiomatosis that included bone lesions and subdiaphragmatic extension. Both of these latter cases were complicated by chylothorax after attempted removal of the mediastinal lymphangioma. Computed tomography and lymphangiography were helpful in determining the extent of the disease and the cystic and lymphatic nature of the mass. The patient with Gorham's disease had extensive lymphangiomatosis of the thorax and recurrent chylothorax; surgical treatment was unsuccessful. Although lymphangioma is a benign tumor, its infiltrative tendency complicates its removal and contributes to its postoperative recurrence.

Clinical outcome of respiratory failure in patients requiring prolonged (greater than 24 hours) mechanical ventilation.

Patients requiring prolonged (greater than 24 hours) mechanical ventilation have various conditions that result in respiratory failure. All patients requiring prolonged mechanical ventilation were subdivided into the following six groups: uncomplicated acute lung injury; respiratory failure complicated by multisystem failure; previous lung disease; trauma; other medical causes; and routine postoperative ventilation. During a one-year period, 327 patients required prolonged mechanical ventilation; acute lung injury and chronic obstructive pulmonary disease were the predominant conditions. Sepsis was both the major predisposing factor for and complication of acute lung injury. Mortality for patients with acute lung injury was 40 percent in the uncomplicated group and 81 percent in patients with acute lung injury complicated by multisystem failure. Acute respiratory failure in association with acute renal failure had a mortality of 89 percent. Number of organ systems involved also correlated with mortality. In patients with chronic obstructive pulmonary disease and pneumonitis or retained secretions, mortality was lower (30 percent), but a significant percentage of these patients (43 percent) became ventilator-dependent. Ventilator dependence did not significantly increase mortality during the course of respiratory failure.

Usual interstitial pneumonitis is a T-cell alveolitis.

Usual interstitial pneumonitis (UIP) is an idiopathic inflammatory disorder that produces scarring of the lung parenchyma. We studied open-lung biopsies of 13 patients with UIP using immunohistological staining and monoclonal antibodies. T lymphocytes (Leu 4+) accounted for 59% of cells in the alveolar septal infiltrates in UIP and OKT8+ cells accounted for the majority of T lymphocytes in most cases. OKM1+ granulocytes comprised a smaller percentage (14%) of the alveolar infiltrates. Granulocytes were most frequent within cystic airspaces and inflamed small airways. Class II HLA (Ia) antigens were expressed on lymphocytes, macrophages, endothelial cells, and alveolar type II cells in lungs with UIP. This study demonstrates that altered immunoregulatory subsets are present in the lungs of patients with UIP and suggests the possibility that activated T cells may play a role in the pathogenesis of this disorder.

Intrathoracic manifestations in mixed connective tissue disease.

A high frequency of occurrence of pleuropulmonary manifestations in mixed connective tissue disease (MCTD) has been reported in the literature. A retrospective analysis of 81 adult patients with the diagnosis of MCTD who were examined at our medical center from 1973 through 1977 revealed that pleuropulmonary involvement occurred in 20 (25%). Thirteen patients (16%) had dyspnea, six (7%) had chest pain, and four (5%) had cough. Chest roentgenograms disclosed basal interstitial processes in 15 patients (19%), pleural effusion in 5 (6%), pneumonic infiltrates in 3 (4%), and pleural thickening in 2 (2%). Abnormalities of pulmonary function were noted in 9 (69%) of 13 patients tested, and esophagographic abnormalities were present in 19 (53%) of 36 patients tested. Systemic corticosteroid therapy was beneficial in two of the eight patients so treated, and nonsteroidal anti-inflammatory drugs resolved most of the clinical features in four of the seven patients so treated. Six patients died during a 5-year follow-up period.

Postoperative respiratory care after transsternal thymectomy in myasthenia gravis. A 3-year experience in 53 patients.

During a three-year period, 53 patients with myasthenia gravis underwent transsternal thymectomy by a partial sternum-splitting technique at our institution. This procedure was carried out (1) because an x-ray film or a computed tomography scan had suggested the presence of a thymoma or (2) to manage symptoms of myasthenia gravis. In 41 patients the endotracheal tube was removed in the post-anesthesia recovery room. The remaining 12 patients were extubated in the Respiratory Care Unit--in five, after prolonged mechanical ventilation. From our experience, the only factor useful for predicting the probable need for prolonged postoperative mechanical ventilation is the degree of bulbar involvement. Patients in Osserman classification groups 3 and 4 have an extremely high incidence of postoperative respiratory failure. Consideration should be given to the use of preoperative plasmapheresis in myasthenia gravis patients who have significant bulbar symptoms.

Plasmapheresis in the treatment of ventilator-dependent myasthenia gravis patients. Report of four cases.

During a 42-month period, we used plasmapheresis to treat four cases of myasthenia gravis with refractory respiratory failure. All four patients were ventilator dependent for prolonged periods and were not responding to management with cholinesterase inhibitors and corticosteroids. All four patients rapidly responded to the plasmapheresis; respiratory muscle strength returned sufficiently to allow discontinuation of assisted mechanical ventilation and removal of the artificial airway. In our experience, plasmapheresis is indicated in the treatment of the myasthenia gravis patient with respiratory failure which is refractory to conventional drug therapy.

Continuous monitoring of mixed venous oxygen saturation.

Continuous monitoring of arterial oxygen tension is not sufficiently accurate for practical use in adults. Because of the shape of the hemoglobin dissociation curve, fluctuations at higher levels of oxygen tension are not reflected by corresponding changes in saturation; consequently, measurement of saturation at these levels also lacks sensitivity in detecting physiologic instability. However, at the lower levels of oxygen present in venous blood, a linear relationship exists between saturation and tension. The use of improved fiberoptic oximetry systems in conventional pulmonary artery flotation catheters has made the bedside application of this relationship of practical value in the continuous assessment of mixed venous oxygen saturation. Our own experience with it extends to more than 630 patients. Changes predictive of cardiorespiratory instability and instantaneous response to nursing or therapeutic maneuvers make this technique highly effective in the care of the critically ill.

Clinical implications of variation in total venoarterial shunt fraction calculated by different methods during severe acute respiratory failure.

Ventilation-perfusion imbalance is the major physiologic disturbance that produces hypoxemia in acute respiratory failure, and total venoarterial shunt fraction is frequently used as a measure of its severity. Ninety-one total venoarterial shunt fractions were calculated from 29 patients with severe acute respiratory failure. Four different methods were used for each estimation, only two of which considered the influence of cardiac output and tissue oxygen uptake. The differences among the results were statistically significant and rendered invalid those that were calculated independently of mixed venous oxygen values. Lack of uniformity of the methods that have been used for calculating shunts in respiratory failure makes it difficult to compare individual patients or groups of them from previous reports. Use of a standard method is desirable so that statistical evaluation of severity and response to treatment can be undertaken. Older data on which therapeutic decisions may be based can have misleading variability from those derived from currently accepted techniques and could appreciably influence patient care.

Mechanical ventilation for respiratory failure in myasthenia gravis. Two-year experience with 22 patients.

We evaluated a 2-year experience involving 22 patients who required prolonged mechanical ventilation for respiratory failure associated with myasthenia gravis. The most frequent cause of respiratory failure was operation, and the most common type of procedure was thymectomy. Next in frequency as exacerbating factors were myasthenic crisis and cholinergic crisis. Of the 22 patients, 21 survived and were weaned from the ventilator after 1 to 32 days of respiratory support.

Avoidance of aggravated hypoxemia during measurement of mean pulmonary artery wedge pressure in ARDS.

A marked drop occurs in mixed venous oxygen saturation during temporary interruption of mechanical ventilation. To avoid this potentially dangerous problem and eliminate possible errors induced by associated hemodynamic changes, a simple electronic circuit was constructed for measurement of mean pulmonary artery wedge pressure without separation of the patient from the ventilator. Its 12-second time constant was sufficient to cover two to four respiratory cycles. In 50 ventilator-supported patients with the adult respiratory distress syndrome, it was shown that the value obtained from the circuit was not different from the instantaneous value obtained at the end of expiration during temporary cessation of mechanical ventilation, but was different from the pulmonary artery diastolic pressure. The circuit value was not affected by positive end-expiratory pressures up to 10 cm H2O. The method is sufficiently accurate for its intended purpose, improves the care of these severely-ill patients, and can be safely used without a physician being present.

Respiratory failure in Guillain-Barré syndrome: a 6-year experience.

Seventy-nine patients with acute Guillain-Barré syndrome were seen during a 6-year period. Twenty-one were admitted to a respiratory intensive care unit, where they remained for 58 +/- 26 days (range 14 to 105 days). Thirteen patients required nasotracheal intubation followed by tracheostomy and mechanical ventilation. The tracheostomy tube was in place for an average of 50 +/- 27 days (range 10 to 104 days). Four patients had complications of tracheostomy; two of these were significant, and one of them led directly to the patient's death. There were no complications due to mechanical ventilation, from which 11 patients were successfully weaned after a mean period of 37 +/- 29 days (range 7 to 93 days). Three of the 79 patients (3.8%) died of complications of their disease or its treatment. Respiratory failure in this condition is protracted and its complications are mainly those of prolonged endotracheal intubation with a tracheostomy tube.

The adult respiratory distress syndrome.

Acute lung injury from a variety of causes may result in capillary leakage and the nonhydrostatic edema of the adult respiratory distress syndrome. The mechanism of development of this syndrome is not yet fully understood. There is increasing hypoxemia from disturbance of normal ventilation-perfusion relationships in the lung and progressive loss of compliance. Treatment is empiric and requires the supportive use of mechanical ventilation and high inspired oxygen fractions, usually with the addition of positive end-expiratory pressure in the breathing circuit. Careful monitoring of respiratory and hemodynamic variables is essential in patient care. In spite of considerable experience, the mortality rate remains high.

Accumulation of radionuclide-labeled platelets and fibrinogen in paraquat-damaged rat lungs.

After intraperitoneal injection of paraquat, rats showed evidence of neurologic and respiratory damage and had a mortality rate of 41% in 3 days. The lungs quadrupled in weight between the third and the fifth day. Pulmonary edema and extravascular fibrin and platelets were identified by light and transmission electron microscopy. As early as 4 h after injection of the paraquat, 51Cr from labeled platelets began accumulating in the lungs. The peak was reached by 48 h; 125I from labeled fibrinogen also concentrated in the lungs of treated rats. Total complement was unchanged. The paraquat-treated rat is a suitable model for study of the behavior of fibrin and platelets in permeability pulmonary edema. Disturbances of copper metabolism deserve further investigation.