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Biomedical subjects

J G Weg

Publications and source records attributed to J G Weg.

At least 37 records · Page 2Linked to original sources
PubMed1994

Safety and potential efficacy of an aerosolized surfactant in human sepsis-induced adult respiratory distress syndrome.

OBJECTIVE: To evaluate the safety and potential efficacy of aerosolized surfactant in intubated patients with adult respiratory distress syndrome (ARDS). DESIGN: A prospective, double-blind, placebo-controlled, randomized, parallel, multicenter pilot clinical trial. PATIENTS: A total of 51 patients with sepsis-induced ARDS were entered into the study within 18 hours of developing sepsis or sepsis syndrome. INTERVENTION: Patients were randomized into four treatment groups in a 2:1:2:1 ratio, as follows: 12 hours of surfactant per day, 12 hours of 0.6% saline per day, 24 hours of surfactant per day, and 24 hours of 0.6% saline per day. Surfactant or saline was aerosolized continuously for up to 5 days using an in-line nebulizer that aerosolized only during inspiration. MAIN OUTCOME MEASURES: Ventilatory data, arterial blood gases, and hemodynamic parameters were measured at baseline, every 4 or 8 hours during the 5 days of treatment, 24 hours after treatment, and 30 days after treatment, at which time mortality was also assessed. Safety was evaluated throughout the 30 days of the study. RESULTS: Surfactant was administered safely in ventilated patients when given continuously throughout the 5 days using the nebulizer system. Although there were no differences in any physiological parameters between the treatment groups, there was a dose-dependent trend in reduction of mortality from 47% in the combined placebo group to 41% and 35% in the groups treated with 12 hours and 24 hours of surfactant per day, respectively. CONCLUSIONS: Aerosolized surfactant was well tolerated when administered on a continuous basis for up to 5 days; however, at the doses given, it did not result in significant improvements in patients with sepsis-induced ARDS.

APACHE↗
PubMed1994

Aortobronchial fistula 13 years following repair of aortic transection.

We describe a 56-year-old man with the new onset of hemoptysis, increasing in frequency and magnitude, initially diagnosed and treated as pulmonary embolism. Bronchoscopy, computed tomography, and thoracic aortography were performed twice before the diagnosis was made. Thirteen years previously, the patient underwent thoracic aortic interposition graft placement for aortic laceration as a result of a motor vehicle accident. The second aortogram demonstrated a small pseudoaneurysm at the expected proximal graft suture line. Aortobronchial fistula, a rare cause of hemoptysis, was diagnosed. The patient underwent successful resection of the graft and placement of a new dacron interposition graft. All cultures, including blood, sputum, and operative specimen cultures, were negative. The patient is alive and well 1 year following surgery.

Aneurysm, False↗
PubMed1993

Effects of dense, high-volume, artificial surfactant aerosol on a heated exhalation filter system.

OBJECTIVE: To evaluate a supplemental heated filter system during mechanical ventilation with continuous nebulization of an artificial surfactant by a new, high-volume nebulizer. DESIGN AND METHODS: A new nebulizer system, containing artificial surfactant, provided half of a 20-L minute ventilation and the remainder of this minute ventilation was provided by a commonly used mechanical ventilator. Ventilation sources were joined in the inspiratory limb of the breathing circuit, which was connected to a test lung system. A supplemental filter system was placed upstream of the ventilator's heated filter in the expiratory limb of the circuit. Circuit pressures at the inlet of the supplemental filter (P1), between the filters (P2), and after the ventilator expiratory filter (P3) were monitored and recorded. Nebulizer canisters containing artificial surfactant were replaced every 4 hrs. The performance of four supplemental filters in continuous use was examined. Another four filters were each used over 4 hrs, steam autoclaved, and reused. SETTINGS: The ventilator was set at a rate of 20 breaths/min, with a tidal volume of 0.5 L, a flow rate of 40 L/min, and positive end-expiratory pressure of 10 cm H2O. The nebulizer provided an equal volume and flow rate so that the delivered tidal volume was 1.0 L with a flow rate of 80 L/min. RESULTS: Ventilator failure and/or excessive airway pressure caused by increased filter resistance occurred at a mean of 7.3 +/- 1.3 (SD) hrs of continuous ventilation. Mean P1-peak increased from 67.5 +/- 8.2 to 94.0 +/- 10.7 cm H2O (p < .001) and P1-baseline increased from 9.3 +/- 1.0 to 53.5 +/- 17.1 cm H2O (p = .014). Filters that were autoclaved after 4 hrs of ventilation and reused lasted a total of 7.0 +/- 1.3 hrs. Mean P1-peak increased from 68.9 +/- 4.9 to 84.8 +/- 19.1 cm H2O and P1-baseline increased from 9.5 +/- 1.7 to 30.8 +/- 14.2 cm H2O (p < .05). CONCLUSIONS: The supplemental filter system was able to protect the ventilatory exhalation sensors for approximately 7 hrs at a minute ventilation of 20 L/min. Steam sterilization did not extend the supplemental filter life.

Aerosols↗
PubMed1992

The clinical course of pulmonary embolism.

BACKGROUND: Pulmonary embolism is a potentially fatal disorder. Information about the outcome of clinically recognized pulmonary embolism is sparse, particularly given that new treatments for more seriously ill patients are now available. METHODS: We prospectively followed 399 patients with pulmonary embolism diagnosed by lung scanning and pulmonary angiography, who were enrolled in a multicenter diagnostic trial. We reviewed all hospitalizations, all new investigations of pulmonary embolism, and all deaths among the patients within one year of diagnosis. RESULTS: Of the 399 patients, 375 (94 percent) received treatment for pulmonary embolism, usually conventional anticoagulation. Only 10 patients (2.5 percent) died of pulmonary embolism; 9 of them had clinically suspected recurrent pulmonary embolism. Clinically apparent pulmonary embolism recurred in 33 patients (8.3 percent), of whom 45 percent died during follow-up. Ninety-five patients with pulmonary embolism (23.8 percent) died within one year. The conditions associated with these deaths were cancer (relative risk, 3.8; 95 percent confidence interval, 2.3 to 6.4), left-sided congestive heart failure (relative risk, 2.7; 95 percent confidence interval, 1.5 to 4.6), and chronic lung disease (relative risk, 2.2; 95 percent confidence interval, 1.2 to 4.0). The most frequent causes of death in patients with pulmonary embolism were cancer (in 34.7 percent), infection (22.1 percent), and cardiac disease (16.8 percent). CONCLUSIONS: When properly diagnosed and treated, clinically apparent pulmonary embolism was an uncommon cause of death, and it recurred in only a small minority of patients. Most deaths were due to underlying diseases. Patients with pulmonary embolism who had cancer, congestive heart failure, or chronic lung disease had a higher risk of dying within one year than did other patients with pulmonary embolism.

Adult↗
PubMed1992

Pulmonary responses of asthmatic and normal subjects to different temperature and humidity conditions in an environmental chamber.

Determining the possible adverse health effects of air pollutants can be complicated by differences in the environmental conditions of temperature and humidity. To evaluate the potentially confounding effects of differences in temperature and humidity, we exposed 8 normal male subjects and 8 male subjects with asthma to the extremes in temperature and humidity that could be maintained in an environmental chamber. We performed serial pulmonary function tests for these subjects before and during 6 hr exposure periods on 5 separate occasions: cold, dry (10 degrees C, 10% relative humidity); cold, humid (10 degrees C, 50% relative humidity); normal ambient (22 degrees C, 40% relative humidity); hot, dry (37 degrees C, 15% relative humidity); and hot, humid (37 degrees C, 60% relative humidity). The exposure period included a 12 min exercise on a cycle ergometer. We found no significant change in spirometry, airways resistance, or diffusing capacity for either group of subjects at rest alone over the 6 hr period of exposure for any exposure condition. However, there were changes in spirometry and airways resistance as a result of the 12 min period of exercise. The subjects with asthma had significant decreases in forced expiratory volume in 1 sec (FEV1) (20-21%) and increases in specific airways resistance when exercising in conditions of cold and dry, cold and humid, and hot and dry. The normal subjects had an average increase in FEV1 of approximately 6% when exercising in the hot and humid conditions. We found significant correlations for the changes in FEV1 with the water content of the exposure conditions for both groups of subjects. We also found that the work performance (expressed as the external work performed divided by the oxygen consumed) was decreased for the subjects in both groups at the conditions of the higher temperature (37 degrees C) compared with the lower temperature (10 degrees C). These results confirm that controlling for the conditions of temperature and humidity is essential in chamber studies, field studies, or epidemiologic evaluations determining the adverse effect of an air pollutant.

Adult↗
PubMed1992

Complications and validity of pulmonary angiography in acute pulmonary embolism.

BACKGROUND: The Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) addressed the value of ventilation/perfusion scans in acute pulmonary embolism (PE). The present study evaluates the risks and diagnostic validity of pulmonary angiography in 1,111 patients who underwent angiography in PIOPED: METHODS AND RESULTS: Complications were death in five (0.5%), major nonfatal complications in nine (1%), and less significant or minor in 60 (5%). More fatal or major nonfatal complications occurred in patients from the medical intensive care unit than elsewhere: five of 122 (4%) versus nine of 989 (1%) (p less than 0.02). Pulmonary artery pressure, volume of contrast material, and presence of PE did not significantly affect the frequency of complications. Renal dysfunction, either major (requiring dialysis) or less severe, occurred in 13 of 1,111 (1%). Patients who developed renal dysfunction after angiography were older than those who did not have renal dysfunction: 74 +/- 13 years versus 57 +/- 17 years (p less than 0.001). Angiograms were nondiagnostic in 35 of 1,111 (3%), and studies were incomplete in 12 of 1,111 (1%), usually because of a complication. Surveillance after negative angiograms showed PE in four of 675 (0.6%). Angiograms, interpreted on the basis of consensus readings, resulted in an unchallenged diagnosis in 96%. CONCLUSIONS: The risks of pulmonary angiography were sufficiently low to justify it as a diagnostic tool in the appropriate clinical setting. Clinical judgment is probably the most important consideration in the assessment of risk.

Acute Disease↗
PubMed1992

The diagnosis of acute pulmonary embolism in patients with chronic obstructive pulmonary disease.

The clinical features and noninvasive tests, including ventilation perfusion (V/Q) lung scans, were assessed in 108 patients with chronic obstructive pulmonary disease (COPD) suspected of having pulmonary embolism (PE). Twenty-one (19 percent) of 108 patients had PE. In the majority of patients, it was impossible to distinguish between patients with and without PE by clinical assessment alone. However, when a high clinical index of suspicion was present, PE was confirmed by angiography in three of three patients, but the V/Q scan was of intermediate probability. No roentgenographic abnormalities distinguished between PE and no PE. There was no difference between the alveolar-arterial oxygen gradients in either group, nor was there evidence of a reduction in the PaCO2 in patients with PE who had prior hypercapnia. Among the 108 patients with COPD, high, intermediate, low, and normal/near normal probability scans were present in 5 percent, 60 percent, 30 percent, and 5 percent, respectively. The frequency of PE in these V/Q scan categories was five (100 percent) of five, 14 (22 percent) of 65, two (6 percent) of 33, and zero (0 percent) of five, respectively. In conclusion, in the majority of patients, the V/Q scan diagnosis is usually intermediate and such patients require further investigational studies, including angiography. However, among the few patients who demonstrated a high probability lung scan, there was a high positive predictive value for PE effectively avoiding the need for further studies. In those patients with low probability or near normal/normal V/Q scans, the negative predictive value was not lower than the general hospital population.

Acute Disease↗
PubMed1991

Usefulness of noninvasive diagnostic tools for diagnosis of acute pulmonary embolism in patients with a normal chest radiograph.

The value of bedside examination and noninvasive tests in the diagnosis of acute pulmonary embolism (PE) among patients with a normal chest radiograph was investigated. Normal chest radiographs were present in 20 of 260 patients (8%) with acute PE and in 113 of 642 (18%) with suspected acute PE, in whom the diagnosis was excluded. A partial pressure of oxygen in arterial blood less than or equal to 70 mm Hg in a dyspneic patient with a normal chest radiograph was more often seen among patients with PE (9 of 17, 53%) than among patients in whom PE was excluded (18 of 93, 19%; p less than 0.01). However, no combinations of blood gases, signs and symptoms were strictly diagnostic. High probability ventilation/perfusion scans among patients with a normal chest radiograph were indicative of PE in only 6 of 9 patients (67%). Among patients with low-probability ventilation/perfusion scans, 8 of 47 (17%) had PE. This study showed that the combination of dyspnea and hypoxia in a patient with a normal chest radiograph is a useful clue to the diagnosis of PE. Although intuition suggested that ventilation/perfusion scans would yield better results in patients with a normal chest radiograph, the ability to diagnose PE by ventilation/perfusion scans in this subset of patients was not enhanced, except by a reduction of the percentage of patients with intermediate probability scans.

Acute Disease↗
PubMed1991

Oxygen transport in adult respiratory distress syndrome and other acute circulatory problems: relationship of oxygen delivery and oxygen consumption.

OBJECTIVE: To evaluate the evidence that oxygen consumption (VO2) is pathologically dependent on oxygen delivery (DO2). DATA SOURCES: Studies published since 1972 with their relevant bibliographies and computerized search of MEDLINE. STUDY SELECTION: All clinical papers reporting the relationship of: VO2 to DO2 in the adult respiratory distress syndrome (ARDS), sepsis, other critically ill patients, and normal individuals; cardiac output determined by measured VO2 to calculated VO2 from the arterial-mixed venous oxygen difference; blood lactate to DO2; and selected basic science studies. DATA EXTRACTION: Study quality was assessed and all pertinent data were summarized. RESULTS OF DATA EXTRACTION: Normal individuals display physiologic dependence of VO2 at very low levels of DO2 (330 mL/min.m2). Pathologic dependence of VO2 on DO2 entails two concepts: a) VO2 varies directly with DO2 over a wide range of DO2 and b) of particular import, tissue oxygen extraction is compromised. This pathologic supply dependence was initially identified in patients with ARDS; subsequently, it has been demonstrated in patients with sepsis and in a variety of other critically ill individuals. There are substantial, but not uniform, data documenting this dependence of VO2 on DO2 in ARDS. In some studies, this relationship correlates best with increased lactate concentrations. However, increased blood lactate concentrations do not accurately track other evidence of tissue hypoxia. Some researchers have attributed the finding of this supply dependency to artifact, when VO2 is determined by the arterial-mixed venous oxygen difference. However, when these methods are compared, the correlation is excellent. Others have raised the concern that appreciable changes in VO2, even over short periods of time, may result in physiologic increases in DO2. However, when "control" groups have been contemporaneously compared with patients with ARDS using the same methodology, they have not shown supply dependency. Interwoven throughout the studies reviewed is overwhelming and uniform evidence that both mixed venous oxygen tension (PVO2) and mixed venous oxygen content (CVO2) correlate poorly with cardiac output, DO2, or VO2. The inconsistencies in identifying pathologic DO2 dependency may well reflect the unknown variables that exist in patients with ARDS, perhaps better labeled, multiple organ system failure. CONCLUSIONS: Pathologic dependence of VO2 on DO2, especially the inability to increase tissue oxygen extraction, is present in most patients with ARDS and many other critically ill individuals. PVO2 and CVO2 are both unreliable indicators of cardiac output, DO2, or VO2.

Biological Transport↗
PubMed1991

Clinical, laboratory, roentgenographic, and electrocardiographic findings in patients with acute pulmonary embolism and no pre-existing cardiac or pulmonary disease.

The history, physical examination, chest radiograph, electrocardiogram and blood gases were evaluated in patients with suspected acute pulmonary embolism (PE) and no history or evidence of pre-existing cardiac or pulmonary disease. The investigation focused upon patients with no previous cardiac or pulmonary disease in order to evaluate the clinical characteristics that were due only to PE. Acute PE was present in 117 patients and PE was excluded in 248 patients. Among the patients with PE, dyspnea or tachypnea (greater than or equal to 20/min) was present in 105 of 117 (90 percent). Dyspnea, hemoptysis, or pleuritic pain was present in 107 of 117 (91 percent). The partial pressure of oxygen in arterial blood on room air was less than 80 mm Hg in 65 of 88 (74 percent). The alveolar-arterial oxygen gradient was greater than 20 mm Hg in 76 of 88 (86 percent). The chest radiograph was abnormal in 98 of 117 (84 percent). Atelectasis and/or pulmonary parenchymal abnormalities were most common, 79 of 117 (68 percent). Nonspecific ST segment or T wave change was the most common electrocardiographic abnormality, in 44 of 89 (49 percent). Dyspnea, tachypnea, or signs of deep venous thrombosis was present in 107 of 117 (91 percent). Dyspnea or tachypnea or pleuritic pain was present in 113 of 117 (97 percent). Dyspnea or tachypnea or pleuritic pain was present in 113 of 117 (97 percent). Dyspnea or tachypnea or pleuritic pain or atelectasis or a parenchymal abnormality on the chest radiograph was present in 115 of 117 (98 percent). In conclusion, among the patients with pulmonary embolism that were identified, only a small percentage did not have these important manifestations or combinations of manifestations. Clinical evaluation, though nonspecific, is of considerable value in the selection of patients in whom there is a need for further diagnostic studies.

Acute Disease↗
PubMed1991

Diagnostic utility of ventilation/perfusion lung scans in acute pulmonary embolism is not diminished by pre-existing cardiac or pulmonary disease.

The purpose of this study was to assess the impact of prior cardiac or pulmonary disease upon the utility of ventilation/perfusion (V/Q) scans in the diagnosis of acute pulmonary embolism (PE). Ventilation/perfusion scans were evaluated among 365 patients with no prior cardiac or pulmonary disease and compared to V/Q scans in 526 patients with prior cardiac or pulmonary disease. Among patients with no prior cardiac or pulmonary disease, PE was present in 117 and PE was excluded in 248. Among patients with prior cardiac or pulmonary disease, PE was present in 140 and excluded in 386. The positive predictive value for PE of high probability V/Q scans among patients with prior cardiac or pulmonary disease, 55 of 66 (83 percent), was not significantly lower than among patients without prior cardiac or pulmonary disease, 50 of 54 (93 percent) (NS). The positive predictive value of low probability V/Q scans was similar with prior cardiac or pulmonary disease, 25 of 182 (14 percent), and without prior cardiac or pulmonary disease, 17 of 113 (15 percent) (NS), as was the predictive value of near normal/normal V/Q scans, 2 of 51 (4 percent), vs 3 of 79 (4 percent) (NS). The sensitivity of high probability V/Q scans, with pre-existing cardiac or pulmonary disease and without, 55 of 140 (39 percent) vs 50 of 117 (43 percent), did not differ significantly. The specificity of high probability V/Q scans with prior cardiac or pulmonary disease and without, 375 of 386 (97 percent) vs 244 of 248 (98 percent) was also similar (NS). In conclusion, the diagnostic utility of V/Q scans for acute PE was not impaired by the presence of pre-existing cardiac or pulmonary disease. Fewer patients, however, with no prior cardiac or pulmonary disease, had intermediate (indeterminate) V/Q scans.

Acute Disease↗
PubMed1989

Safe intrahospital transport of critically ill ventilator-dependent patients.

STUDY OBJECTIVE: To determine whether manual ventilation during intrahospital transport of mechanically ventilated critically ill patients results in blood gas and/or hemodynamic abnormalities. DESIGN: A single-blind prospective study evaluated arterial blood gas, blood pressure, heart rate, and arrhythmia changes during mechanical ventilation and manual transport ventilation. SETTING: University hospital ICUs and various diagnostic or treatment areas. PATIENTS: Twenty mechanically ventilated critically ill patients during intrahospital transport. INTERVENTION: Each patient received mechanical ventilation (MECH) with a volume ventilator while in the ICU and at the study/treatment area. They were manually ventilated (MAN) by a respiratory therapist during transport between areas. MEASUREMENTS AND MAIN RESULTS: The MECH settings were: VT = 0.75 +/- 0.17 L; f = 16 +/- 4; VE = 12.6 +/- 4.3 L/min; FIO2 = 0.46 +/- 0.2. Mean peak Paw = 31 +/- 12 cm H2O and mean effective Cst = 44 +/- 15 ml/cm H2O. No hemodynamic abnormalities were observed. Arterial blood gas values did not vary to any clinically significant degree, except in two patients: one patient had a reduced PaO2 and increased PaCO2 associated with an accidental O2 disconnection and clamped chest tube; another patient had an increased pH by 0.13 units with only a 9 mm Hg fall in PaCO2. CONCLUSIONS: Manual ventilation during intrahospital transport of critically ill mechanically ventilated patients is safe provided the person performing manual ventilation knows the inspired oxygen fraction and minute ventilation required before transport and is trained to approximate them during transport.

Critical Care↗