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Biomedical subjects

K M Moser

Publications and source records attributed to K M Moser.

At least 109 records · Page 6Linked to original sources
PubMed1987

Modifications of techniques and early results of pulmonary thromboendarterectomy for chronic pulmonary embolism.

In 1980 we described bilateral pulmonary thromboendarterectomy with median sternotomy, cardiopulmonary bypass, deep hypothermia, and circulatory arrest for the relief of pulmonary hypertension caused by chronic pulmonary embolism. In our subsequent experience, which totals 41 patients, we have identified three groups of patients characterized by differences of intraoperative management. In Group A (N = 16) myocardial protection consisted of single-dose crystalloid cardioplegia followed by pericardial irrigation with cold saline. Extrapericardial dissection of the pulmonary arteries was performed. Group B (N = 7) was treated the same as Group A except for the substitution of saline slush contained in a laparotomy pad for iced saline. In Group C (N = 18) myocardial protection was single-dose blood cardioplegia followed by the application of a specially designed cooling jacket to the right and left ventricles. Another modification was that of intrapericardial dissection of the pulmonary arteries with extension of the dissection into the hilar tissues without entrance into the pleural spaces. The hospital mortalities of Groups A, B, and C were 18.7%, 14.3%, and 5.5%, respectively (not statistically significant differences). However, other statistically significant differences (p less than 0.05) among the groups were observed: Phrenic nerve paresis occurred in five of seven (71%) Group B patients but in no Group A or C patients; Group B patients required ventilatory support for 32.2 days compared with 8.4 days for Group A and 6.2 days for Group C; time in the intensive care unit was 36 days for Group B patients versus 13 for Group A and 10.3 for Group C; pulmonary vascular resistance decreased 59% (649 versus 259) intraoperatively in 13 patients in Group C. We believe simultaneous bilateral pulmonary thromboendarterectomy with median sternotomy, cardiopulmonary bypass, deep hypothermia with circulatory arrest, and the modified methods of myocardial preservation and dissection represent current optimal surgical management of this problem.

Adult↗
PubMed1986

Low-dose PGI2 prevents monocrotaline-induced thromboxane production and lung injury.

In animals, monocrotaline induces an acute lung injury secondary to capillary endothelial damage. To date, no reports have appeared dealing with the role of prostaglandins in monocrotaline-induced injury. Our studies, in dogs, revealed that monocrotaline (30 mg/kg iv) caused an acute and persistent thrombocytopenia, lung platelet deposition, pulmonary hypertension, and increased extravascular lung water (EVLW). The pulmonary hypertensive response was biphasic. Thromboxane B2 levels were similarly biphasic, peaking at 5 min and 2 h. The levels of 6-keto-PGF1 alpha peaked at 30 min and returned to base line at 3 h. Pulmonary vascular resistance paralleled thromboxane levels. Infusion of prostacyclin (PGI2) at 50 ng X kg-1 X min-1 effectively prevented the thrombocytopenia, lung platelet deposition, pulmonary hypertension, and increased EVLW; and it decreased excess thromboxane production by 79%. These results suggest that platelet activation and lung sequestration play a role in acute lung injury due to monocrotaline, and that the resultant thromboxane production may contribute to the pulmonary hypertension. PGI2 ameliorates monocrotaline-induced injury, perhaps by preventing platelet activation.

6-Ketoprostaglandin F1 alpha↗
PubMed1986

Reperfusion pulmonary edema after pulmonary artery thromboendarterectomy.

Pulmonary artery thromboendarterectomy (PAT) is a potentially curative procedure in chronic, major vessel thromboembolic pulmonary hypertension. However, postoperative reperfusion pulmonary edema (RPE) has been a serious complication, often requiring prolonged mechanical ventilation. This entity has been described only anecdotally in the past. To characterize it more fully, we retrospectively analyzed the course and potential determinants of RPE after thromboendarterectomy in 22 patients who had PAT at our institution from 1969 through 1984. Particular attention was directed to clinical data, thrombus location, areas operated, postoperative roentgenograms, and preoperative and postoperative hemodynamic data. In all patients but 1, RPE developed within 72 h after surgery, corresponding to anatomic locations distal to vessels subjected to PAT. Regions of lung not reperfused at surgery were uniformly spared. Pulmonary capillary wedge and/or left atrial pressures preoperatively and postoperatively were not elevated. None of the preoperative data predicted which patients would develop more persistent RPE. These observations suggest that the phenomenon of RPE is a peculiar, focal form of pulmonary edema, the basis for which remains to be defined.

Adult↗
PubMed1986

Pulmonary vascular occlusion and fibrosing mediastinitis.

Patients with fibrosing mediastinitis causing obstruction of pulmonary veins and arteries may present with many of the historic, physical, and laboratory findings of patients with pulmonary hypertension due to chronic thrombotic obstruction of major pulmonary arteries. Because the latter is subject to surgical correction, and the former is not, it is important to differentiate between the two and to be aware of the similarities in presentation. Three patients with pulmonary hypertension due to compression of pulmonary veins and the right pulmonary artery by fibrosing mediastinitis are presented who illustrate these points. A review of the literature documents other instances in which vascular involvement due to fibrosing mediastinitis has mimicked other types of pulmonary hypertension.

Adult↗
PubMed1986

Comparison of isocapnic hyperventilation and walking exercise training at home in pulmonary rehabilitation.

Eighteen COPD patients enrolled in a comprehensive, multidisciplinary pulmonary rehabilitation program were randomly assigned to perform either: 1) walking, or 2) ventilatory muscle exercise training (VMT) using a prototype, portable device for isocapnic hyperventilation training. Both groups performed exercise training at home. Twelve patients completed the study and follow-up evaluation (five VMT, seven walkers). Pulmonary function did not change in either group. For the VMT patients, there were modest increases in ventilatory muscle endurance and exercise performance. VO2max and VEmax increased significantly. For the walkers, only walking endurance time increased significantly. These results indicate that isocapnic hyperventilation exercise training can be performed successfully by COPD patients in an unsupervised home setting and can lead to improvement in both ventilatory muscle endurance and exercise performance. Walking exercise training did not improve ventilatory muscle endurance.

Aged↗
PubMed1986

Pneumococcal vaccine and patients with chronic lung disease.

We reviewed data that evaluated both the risk for pneumococcal pneumonia in patients with chronic lung disease and the protection afforded these patients by current pneumococcal vaccines. No conclusive documentation of increased risk for pneumococcal pneumonia in this population exists, and data suggest that the protection provided by the vaccine in healthy persons may be reduced in patients with chronic lung disease. We conclude, on the basis of available data, that routine vaccination of all patients with chronic lung disease is not warranted.

Antibodies, Bacterial↗
PubMed1985

Cheyne-Stokes breathing during sleep in patients with left ventricular heart failure.

Fifteen patients with left ventricular heart failure (LVF) without known breathing disorders during sleep had full-night recordings of sleep and breathing to study the incidence and impact of the apnea of Cheyne-Stokes breathing. This group showed a marked degree of sleep-related breathing abnormalities, 40% demonstrating Cheyne-Stokes breathing with five or more central apneas per hour of sleep. Cheyne-Stokes breathing during sleep in patients with LVF predicted an increased short-term mortality rate. All six patients with LVF and Cheyne-Stokes breathing with more than five apneas per hour of sleep were dead within six months, while only three of nine patients without recurrent apnea died within six months, a significant difference (P less than .05) even in this small group. Among seven patients with LVF studied with the polysomnogram, there were statistically significant differences between the Cheyne-Stokes and non-apnea groups in total sleep time, awakening per hour, and the number of arterial desaturations. Although sleep disturbances have been anecdotally described in patients with LVF, no previous investigation has determined the incidence and impact of Cheyne-Stokes breathing during sleep in LVF. Our findings that Cheyne-Stokes breathing predicts an adverse short-term mortality rate confirm the clinical impression that Cheyne-Stokes breathing is a poor prognostic sign in LVF.

Adult↗
PubMed1985

Wedge and subselective pulmonary angiography in pulmonary hypertension secondary to venous obstruction.

Pulmonary wedge or subselective angiography provided key diagnostic information in two cases of pulmonary hypertension secondary to pulmonary venous obstruction. Whereas conventional pulmonary angiograms and ventilation-perfusion lung scans were interpreted as showing embolism, plain radiographs demonstrated Kerley B lines, suggesting venous obstruction. Subselective or wedge angiography of nonopacified arteries verified their anatomical patency and also revealed venous stenoses, collaterals, and atrophy indicative of obstruction.

Adult↗
PubMed1985

Transbronchial needle aspiration in the diagnosis of pneumonia in a canine model.

We evaluated the risk, sensitivity, and specificity of transbronchial needle aspiration (TBNA) in a canine model of unilateral Streptococcus pneumoniae pneumonia and compared the results with our previous studies of these parameters in transthoracic needle aspiration (TTN), a catheter-brush (CB), and transbronchial biopsy (TBB) in the same model. The TBNA was performed in 10 dogs with right lower lobe S. pneumoniae pneumonia. The procedure was uncomplicated, but both the sensitivity and specificity were low (3 of 10 cultures yielded S. pneumoniae; only 1 of the 3 was a pure culture). This compares unfavorably with our experience with the other procedures: 9 of 10 cultures were pure with TBB and CB, and the remaining culture was sterile; 10 of 10 were pure with TTN. Given the present unprotected form of the bronchoscopic aspirating needle, TBNA does not appear to be useful in the diagnosis of bacterial pneumonia despite its usefulness in the diagnosis of intrathoracic malignancy.

Animals↗
PubMed1985

Fiberoptic angioscopy: role in the diagnosis of chronic pulmonary arterial obstruction.

We evaluated the role of fiberoptic angioscopy in eight patients with suspected chronic pulmonary embolic obstruction of the pulmonary arteries. Angioscopy, preceded by ventilation-perfusion lung scans, right-heart catheterization, and pulmonary angiography, resulted in diagnostic changes in four patients: from pulmonary artery agenesis to chronic emboli; from chronic emboli to normal pulmonary arterial intima (primary pulmonary hypertension); from chronic pulmonary emboli to extrinsic compression of a major pulmonary artery (fibrosing mediastinitis); and from suspected agenesis or chronic emboli to a tumor (fibrosarcoma) of the pulmonary artery. Angioscopy also more accurately determined the extent and surgical accessibility of chronic embolic obstruction in the five patients with that disorder; as a result, we decided that the obstruction in one patient was inoperable. No significant complications occurred with angioscopy and we conclude that its direct visualization capability can contribute significantly to the diagnostic evaluation of suspected chronic pulmonary arterial obstruction.

Adult↗
PubMed1985

Influence of perfusion and ventilation scans on therapeutic decision making and outcome in cases of possible embolism.

We examined the influence of perfusion (Q) and ventilation (V) scans on therapeutic decision making and outcome among 229 patients referred for lung scans because embolism was suggested and found that specific V/Q scan patterns strongly influenced postscan decisions regarding initiation, maintenance or cessation of heparin therapy. These therapeutic decisions bore a relationship to outcome (recurrences and death) and disclosed decision-making deficits that need remedy by future investigational and educational efforts.

Decision Making↗
PubMed1984

Diagnosis of acute, diffuse pulmonary infiltrates.

Patients with acute, diffuse pulmonary infiltration that may be infectious or noninfectious present a major diagnostic-treatment challenge. Many options are available during the sequence of diagnosis and treatment. Our bias is to proceed rapidly to the more specific and sensitive invasive diagnostic procedures if clinical and laboratory data are indicative of diffuse involvement or immunosuppression, because a positive outcome appears to be affected by early intervention with appropriate antimicrobial drugs. Such an approach also avoids administration of a potentially toxic and unnecessary antimicrobial "shotgun." Each physician must consider the local expertise and resources available; in our view, however, the patient is best served by, "erring" on the side of early use of invasive procedures.

Acute Disease↗
PubMed1984

Imaging of venous thromboemboli with labeled platelets.

Prevention and optimal treatment of venous thromboembolism requires techniques that can: (1) monitor patients at high risk; (2) promptly detect thromboemboli; (3) follow the course of patients during treatment. Multiple techniques have been introduced to assist in these tasks. Some have not been well validated. Others, while established as of substantial value, have limitations with respect to specificity, sensitivity, patient access, patient acceptability, or risk. The dynamic nature of venous thromboembolism makes it unlikely that any one procedure will satisfy all diagnostic needs. Platelets labeled with 111In (111In-P) have promise as a useful addition to the existing diagnostic armamentarium. Because 111In-P are incorporated into forming and growing thromboemboli, and can provide a gamma camera image, they offer certain potential advantages versus other techniques. However, to establish the clinical value and proper use of the 111In-P technique, additional investigations are needed to determine the impact of thrombus location, age, anticoagulant therapy, and imaging technique and timing upon in vivo visualization of thromboemboli.

Animals↗
PubMed1984

Hemodynamics and gas exchange during angioscopy in the dog.

We have previously developed a technique for the in vivo visualization of the pulmonary arteries in the experimental animal with a fiberoptic instrument (angioscope). To assess the potential hemodynamic and gas exchange effects of angioscopy, we studied five dogs before and after pulmonary embolization. Sequential observations were made of arterial blood gases, mean arterial pressure, pulmonary artery pressure, heart rate, cardiac output, and the electrocardiogram. The most common arrhythmias were ventricular premature contractions which were comparable to those seen with right heart catheterization. Statistically significant, but clinically minor, effects were found on cardiac output, mean arterial pressure, and heart rate in dogs when angioscopy was performed after pulmonary embolization. We conclude that fiberoptic angioscopy does not induce deleterious effects on hemodynamics or gas exchange in the experimental animal, prior to or after embolization.

Animals↗
PubMed1984

Air travel hypoxemia with chronic obstructive pulmonary disease.

Because persons with chronic obstructive pulmonary disease and mild hypoxemia may develop severe hypoxemia during commercial airline flights, we measured arterial blood gas pressures in 13 such patients during a flight in an unpressurized airplane (cabin pressures typical of commercial air travel). At 1650 m, mean arterial Po2 decreased from 68.2 +/- 8.5 (SD) mm Hg to 51 +/- 9.1 mm Hg, and mean arterial Pco2, from 40.9 +/- 0.9 to 37.1 +/- 6.4 mm Hg. At 2250 m, mean arterial Po2 and Pco2 were 44.7 +/- 8.7 and 36.5 +/- 5.8 mm Hg, respectively. No symptoms attributable to hypoxemia occurred. Arterial Po2 measured in patients while breathing room air several weeks before the flight did not correlate with that measured at 1650 m, but arterial Po2 measured less than 2 hours before the flight in room air or a 17.2% oxygen mixture did. Whether a patient will need supplemental oxygen to maintain arterial Po2 above a given value can be predicted from arterial blood samples taken while the patient is breathing a hypoxic gas mixture or room air within 2 hours of the flight.

Aerospace Medicine↗
PubMed1984

The in vivo behavior of granulocytes labeled with indium-111 in a canine model of pneumococcal pneumonia.

Use of [111In]granulocytes in the study of pulmonary inflammation requires study of their in vivo behavior. To study the pulmonary deposition of these cells and their ability to migrate from the capillary to the alveolus, we injected [111In]granulocytes into dogs 24 h after the induction of a right lower lobe pneumococcal pneumonia. Using external imaging, we found rapid clearance of [111In]granulocytes from the uninvolved lung (with a residual radioactivity of 24.5 +/- 4.2% at 4 h). In contrast, 83 +/- 12.4% of the initial radioactivity was present in inflamed lung at 4 h. Bronchoalveolar lavage fluid from the inflamed lung was more cellular than that from control lung, contained a greater fraction of polymorphonuclear leukocytes (82 +/- 4.1% versus 20 +/- 6.2%), and much greater cell-associated radioactivity (ratio of 423:1, inflamed to control). Autoradiography disclosed that this radioactivity was localized to consolidated alveoli and was not prominently distributed in arterioles or venules or in airways larger than 0.6 mm. We conclude that [111In]granulocytes are biologically active in the setting of acute lung inflammation.

Animals↗
PubMed1983

Inhibition of indium-111 platelet accretion onto venous thrombi in dogs by prostacyclin.

The known platelet anti-aggregant effects of prostacyclin (epoprostenol) suggest that it may have therapeutic potential in conditions in which the platelet plays a pathophysiological role. The growth of venous thrombi is one such condition. We have attempted to determine, in a canine model of fresh venous thrombosis, whether prostacyclin infusion inhibits platelet accretion in vivo and how this in vivo event related to hemodynamic and in vitro platelet anti-aggregant effects. Gamma camera imaging over thrombi for accretion of indium-111-labeled platelets disclosed that prostacyclin, at an infusion rate of 50 ng/kg per min, inhibited platelet accretion in vivo and resulted in a 95 +/- 4% decrease in in vitro adenosine diphosphate-induced platelet aggregation, and a decrease in mean arterial pressure to 86 +/- 4% of pre-infusion values. Step-wise decrements of prostacyclin infusion demonstrated that platelet accretion occurred in vivo at infusion rates of approximately 10-20 ng/kg per min and correlated with an in vitro adenosine diphosphate-induced aggregation of 54 +/- 13% of control values. Thus, prostacyclin, in a dose that causes only a mild decrease in systemic pressure, can completely inhibit platelet uptake onto fresh venous thrombi in the dog, and this inhibition correlates closely with in vitro adenosine diphosphate-induced platelet aggregation. The potential therapeutic implications of these findings are discussed.

Animals↗