Prior Cardiopulmonary Disease Research Articles

Point of Care Cardiopulmonary Ultrasound Assessment for Acute Lung Injury Patients after Blood Transfusion

Point of care ultrasound has a very good application prospect in perioperative period because of its dynamic, real-time and repeatable advantages. At the same time, it has high accuracy and can quickly find the common causes of hypoxemia, such as pulmonary edema, atelectasis and pleural effusion. It is a good visualization tool. Perioperative combined use of cardiopulmonary ultrasound, on the basis of excluding cardiac dysfunction, rapid diagnosis of pulmonary edema. The author conducted a study on two cases of acute lung injury induced by a relatively large amount of blood transfusion. The patients had no prior cardiopulmonary disease, no abnormal findings were found on cardiac ultrasound, hypoxemia, and signs of lung injury were found on bedside pulmonary ultrasound.

Propofol infusion syndrome in patients with refractory status epilepticus: An 11-year clinical experience*

Propofol is a sedative, anesthetic, and antiepileptic agent that is frequently used in patients with refractory status epilepticus. Propofol infusion syndrome is a feared complication of propofol use, especially at high infusion rates for prolonged periods. The present study describes the use of propofol and its associated complications in patients with refractory status epilepticus. : Retrospective study with outcome assessment. Intensive care units at Mayo Clinic. Intensive care unit admissions with refractory status epilepticus. None. A computer-assisted search identified 41 consecutive patients from January 1997 to September 2008 admitted to our intensive care unit with refractory status epilepticus, defined by the need for continuous intravenous infusion of anesthetic agents to control seizures. Propofol infusion syndrome was defined per previously published criteria. The study population consisted of 24 males and 17 females with a median age of 51 yrs (range, 0.25- 80). Propofol was used in 31 (76%) of these patients (propofol group), and other agents like midazolam, lorazepam, and pentobarbital were used in the other ten (24%) patients (nonpropofol group). Median hospital (12 days; range, 2-112) and intensive care unit length of stay (9 days; range, 2-95) did not differ among the two groups. Propofol was used for a median of 63 hrs (range, 2-391) with a median cumulative dosage of 12,750 mg (range, 336-57,545). The median peak infusion rate was 67 microg/kg/min (range, 19-200). There were three sudden unexplained cardiorespiratory arrests in the propofol group (3 of 31, 10%), of which two were fatal. These three patients were aged 37, 46, and 55 yrs and had no prior cardiopulmonary disease. Eleven additional patients (11 of 31, 35%) had non-life-threatening features of propofol infusion syndrome. There were no such events noted in the nonpropofol group. The prolonged use of large doses of propofol to treat refractory status epilepticus was associated with significant mortality and morbidity.

How to Use an Article About a Diagnostic Test

Urologists frequently confront diagnostic dilemmas, prompting them to select, perform and interpret additional diagnostic tests. Before applying a given diagnostic test the user should ascertain that the chosen test would indeed help decide whether the patient has a particular target condition. In this article in the Users' Guide to the Urological Literature series we illustrate the guiding principles of how to critically appraise a diagnostic test, interpret its results and apply its findings to the care of an individual patient. The guiding principles of how to evaluate a diagnostic test are introduced in the setting of a clinical scenario. We propose a stepwise approach that addresses the question of whether the study results are likely to be valid, what the results are and whether these results would help urologists with the treatment of their individual patients. Some of the issues urologists should consider when assessing the validity of a diagnostic test study are how the authors assembled the study population, whether they used blinding to minimize bias and whether they used an appropriate reference standard in all patients to determine the presence or absence of the target disorder. Urologists should next evaluate the properties of the diagnostic test that indicate the direction and magnitude of change in the probability of disease for a particular test result. Finally, urologists should ask a series of questions to understand how the diagnostic test may impact the care of their patients. Application of the guides presented in this article will allow urologists to critically appraise studies of diagnostic tests. Determining the study validity, understanding the study results and assessing the applicability to patient care are 3 fundamental steps toward an evidence-based approach to choosing and interpreting diagnostic tests.

Clinical Characteristics of Patients with Acute Pulmonary Embolism: Data from PIOPED II: Stein PD, Beemath A, Matta F, et al. Am J Med 2007;120:871–9

This study from the United States identified the clinical characteristics present in the 192 patients aged 18 years and older diagnosed with pulmonary embolism (PE) in the PIOPED II trial. Chi-squared analysis was used to compare the prevalence of clinical signs and symptoms in patients with and without PE. Additionally, comparisons of continuous variable means were made with the two-tailed Student's unpaired t-test. Of the 192 patients with PE, 133 had no prior cardiopulmonary disease. New dyspnea with exertion or at rest was the most frequent symptom in patients with PE (79%).

Prospective Study of the Clinical Features and Outcomes of Emergency Department Patients with Delayed Diagnosis of Pulmonary Embolism

The authors hypothesized that emergency department (ED) patients with a delayed diagnosis of pulmonary embolism (PE) will have a higher frequency of altered mental status, older age, comorbidity, and worsened outcomes compared with patients who have PE diagnosed by tests ordered in the ED. For 144 weeks, all patients with PE diagnosed by computed tomographic angiography were prospectively screened to identify ED diagnosis (testing ordered from the ED) versus delayed diagnosis (less than 48 hours postadmission). Serum troponin I level, right ventricular hypokinesis on echocardiography, and percentage pulmonary vascular occlusion were measured at diagnosis; patients were prospectively followed up for adverse events (death, intubation, or circulatory shock). Among 161 patients with PE, 141 (88%) were ED diagnosed and 20 (12%) had a delayed diagnosis. Patients with a delayed diagnosis were older than ED-diagnosed patients (61 [+/-15] vs. 51 [+/-17] years; p < 0.001), had a longer median time to heparin administration (33 vs. 8 hours; p < 0.001), and had a higher frequency of altered mental status (30% vs. 8%; p = 0.01) but did not have a higher frequency of prior cardiopulmonary disease (25% vs. 23%). Patients with a delayed diagnosis had equal or worse measures of PE severity (right ventricular hypokinesis on echocardiography, 60% vs. 58%; abnormal troponin I level, 55% vs. 24%); on computed tomographic angiography, ten of 20 patients with a delayed diagnosis had PE in lobar or larger arteries and >50% vascular obstruction. Patients with a delayed diagnosis had a higher rate of in-hospital adverse events (9% vs. 30%; p = 0.01). In this single-center study, the diagnosis of PE was frequently delayed and outcomes of patients with delayed diagnosis were worse than those of patients with PE diagnosed in the ED.

Tromboembolismo pulmonar en el anciano

To describe the characteristics of pulmonary thromboembolism (PTE) in the elderly and to identify potential differences between elderly and non-elderly patients. Retrospective review of 154 consecutive patients diagnosed of PTE in an Internal Medicine service between January 1993 and December 2001. Ninety patients (58.4%) were older than 70 years. Prior cardiopulmonary disease was significantly more frequent in patients older than 70 years (41.1% vs 23.4%, p = 0.03). Deep venous thrombosis (DVT) clinic was significantly less frequent in older than 70 years (36.7% vs 53.1%, p = 0.04). The rest of studied characteristics was similar in both groups. Four patients older than 70 years (4.4%) did not have "classical" symptoms of PTE (dyspnea, centrothoracic pain, pleuritic pain and/or hemoptysis). Three patients older than 70 years (3.3%) did not have "classical" signs of PTE (tachypnea, tachycardia and/or crackles) nor DVT clinic. Three patients older than 70 years (3.3%) had a normal alveolar-arterial oxygen gradient. Hospital death was more frequent in older than 70 years, but without reaching statistical significance (8.9% vs 3.1%, p > 0.05). PTE characteristics are similar in elderly and in non-elderly patients, although DVT clinic is less frequent in elderly. The absence of "classical" symptoms of PTE, the absence of "classical" signs of PTE and DVT clinic, and a normal alveolar-arterial oxygen gradient are very infrequent in elderly with PTE. Hospital mortality in PTE may be higher in patients older than 70 years.

82-Year-Old Man With Recurrent Syncope

82-Year-Old Man With Recurrent Syncope

Diagnostic value of gas exchange tests in patients with clinical suspicion of pulmonary embolism.

OBJECTIVE: To assess the value of parameters derived from arterial blood gas tests in the diagnosis of pulmonary embolism. METHOD: We measured alveolar-arterial partial pressure of oxygen [P(A-a)O2] gradient, PaO2 and arterial partial pressure of carbon diaxide (PaCO2) in 773 consecutive patients with suspected pulmonary embolism who were enrolled in the Prospective Investigative Study of Acute Pulmonary Embolism. DIAGNOSIS: The study design required pulmonary angiography in all patients with abnormal perfusion scans. RESULTS: Of 773 scans, 270 were classified as normal/near-normal and 503 as abnormal. Pulmonary embolism was diagnosed by pulmonary angiography in 312 of 503 patients with abnormal scans. Of 312 patients with pulmonary embolism, 12, 14 and 35% had normal P(A-a)O2, PaO2 and PaCO2, respectively. Of 191 patients with abnormal scans and negative angiograms, 11, 13 and 55% had normal P(A-a)O2, PaO2 and PaCO2, respectively. The proportions of patients with normal/near-normal scans who had normal P(A-a)O2, PaO2 and PaCO2 were 20, 25 and 37%, respectively. No differences were observed in the mean values of arterial blood gas data between patients with pulmonary embolism and those who had abnormal scans and negative angiograms. Among the 773 patients with suspected pulmonary embolism, 364 (47%) had prior cardiopulmonary disease. Pulmonary embolism was diagnosed in 151 (41%) of 364 patients with prior cardiopulmonary disease, and in 161 (39%) of 409 patients without prior cardiopulmonary disease. Among patients with pulmonary embolism, there was no difference in arterial blood gas data between patients with and those without prior CPD. CONCLUSION: These data indicate that arterial blood gas tests are of limited value in the diagnostic work-up of pulmonary embolism if they are not interpreted in conjunction with clinical and other laboratory tests.

Use of the alveolar-arterial oxygen gradient in the assessment of acute pulmonary embolism

To evaluate the utility of the alveolar-arterial ( a-a) oxygen gradient in the diagnosis of acute pulmonary embolism (PE), a retrospective analysis was done of consecutive emergency department patients who underwent pulmonary angiography for the presumed diagnosis of acute PE. Patients were categorized into two groups depending on the presence or absence of prior cardiopulmonary disease. Arterial blood gas samples were chosen for analysis only if obtained when the PE first was suspected clinically (before lung scans or angiograms) and the patient was breathing room air. A total of 152 patients met all study criteria; 59 patients (39%) had angiographically documented emboli. In comparison with the study patients in whom PE was excluded, there was no significant difference in mean Pao 2 (64 v 67 mm Hg) or a-a gradient (39 v 36 mm Hg). Various combinations of the a-a gradient and blood gas levels failed to exclude PE in more than 35% of patients with no prior cardiovascular disease and in 25% of patients with prior cardiovascular disease. The a-a gradient did show a linear correlation with the severity of the PE, as assessed by the Pao 2 ( r = −0.87) and pulmonary artery mean pressure ( r = 0.63). These results indicate that the a-a oxygen gradient, in combination with blood gas levels, may contribute to the formulation of a clinical assessment. However, these laboratory parameters are of insufficient discriminant value to permit exclusion of the diagnosis of PE.

A case of extensive pulmonary embolism presenting as an acute myocardial infarction???notes on its possible pathophysiology

Pulmonary embolism is frequently overlooked but may be fatal. Hence, appropriate diagnosis heavily relies on clinical suspicion. Although most ECG features of pulmonary embolism lack specificity and sensitivity, especially when prior cardiopulmonary disease is present, certain ECG findings may heighten the initial clinical suspicion. This is illustrated in the following report on a case of proven pulmonary embolism complicated with cardiac arrest and prolonged shock. The electrocardiographic presentation was suggestive of an extensive acute myocardial infarction, a pattern which to our knowledge never has been reported on. However, many elements of it pointed to the diagnosis of pulmonary embolism. The multifactorial origin of the ECG findings is discussed.

Prognostic factors in restoration of pulmonary flow after submassive pulmonary embolism: a multiple regression analysis

Defects as evaluated by lung perfusion scans may persist even 6 months after pulmonary embolism (PE), when treatment is withdrawn. The aim of this study was to evaluate the effect of several potential factors on the resolution of lung perfusion defects, both during the first days and at 6 months, when patients were discharged. In a retrospective follow-up cohort study we included 102 patients with PE, diagnosed lung from a ventilation/perfusion (V'/Q') scan, following Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) criteria, together with a phlebographic study of lower extremities or angiography. Lung perfusion scan was performed at diagnosis, and in two follow-up evaluations, at 7-10 days and at 6 months. Potential factors studied were: age; sex; presence of underlying cardiac or pulmonary disease; venous insufficiency; alveolar-arterial pressure difference for oxygen; delay in diagnosis; abnormalities in electrocardiogram or chest radiograph; and the size of defects as shown in lung perfusion scans. All factors were studied with regards to the size of the defects at the two follow-up evaluations, through a univariate statistical analysis and two multiple stepwise regression analysis. Multivariate statistical analysis selected four factors: size of defects at diagnosis; prior cardiopulmonary disease; delay in diagnosis; and sex, as synergistic variables to predict defect size at 7-10 days. On the other hand, the defect size at 7-10 days was the only variable selected as a predictor of the size of defects at 6 months. Resolution of pulmonary defects during the first days after diagnosis of pulmonary embolism is influenced by the initial defect size, prior cardiopulmonary diseases and sex. The size of residual defects at 6 months depends mainly on the size of defects at 7-10 days.

Clinical Characteristics of Patients With Acute Pulmonary Embolism Stratified According to Their Presenting Syndromes

The purpose of this investigation is to determine the characteristics of the history, physical examination, chest radiograph, and ECG, and the ventilation/perfusion (V/Q) lung scan probability in patients with pulmonary embolism (PE) stratified according to their presenting syndrome. In considering a possible diagnosis of acute PE, it is helpful to consider the patient in terms of the presenting syndrome (pulmonary infarction, isolated dyspnea, or circulatory collapse). In assessing the possibility of acute PE, it would be more useful to know the detailed characteristics of the particular syndrome rather than the clinical characteristics of all patients with PE. Patients described in this investigation participated in the national collaborative trial of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). All had PE diagnosed by pulmonary angiography. None had prior cardiopulmonary disease. All examinations and laboratory tests were obtained within 24 h of the pulmonary angiogram and most were within 12 h of the pulmonary angiogram. Among patients with the pulmonary infarction syndrome, 14 of 119 (12%) had neither dyspnea nor tachypnea. Some patients with circulatory collapse did not have dyspnea, tachypnea, or pleuritic pain. A normal ECG was more prevalent among patients with pulmonary infarction syndrome, 45 of 97 (46%), than among patients with isolated dyspnea syndrome, 2 of 21 (10%) (p<0.01). A PaO2 >80 mm Hg was also more prevalent in patients with the pulmonary infarction syndrome, 27 of 99 (27%), than in patients with the isolated dyspnea syndrome, 2 of 19 (11%). A high-probability V/Q lung scan was less prevalent among the pulmonary infarction group, 38 of 119 (32%), than the isolated dyspnea group, 20 of 31 (65%) (p<0.001). Many of the findings in the various syndromes of PE can be understood in terms of the severity of PE as it increases from mild with the pulmonary infarction syndrome to moderate with the isolated dyspnea syndrome to severe with circulatory collapse. The prevalence of various clinical and laboratory characteristics of patients with the syndrome of pulmonary infarction, isolated dyspnea, or circulatory collapse may give clues to the diagnosis or suggest characteristics that may reduce the likelihood of inadvertently discarding the diagnosis of PE.

Prevalence of Acute Pulmonary Embolism in Central and Subsegmental Pulmonary Arteries and Relation to Probability Interpretation of Ventilation/Perfusion Lung Scans

The purpose of this investigation is to determine the prevalence of acute pulmonary embolism (PE) limited to subsegmental pulmonary arteries. Contrast-enhanced helical (spiral) and electron-beam CT, in the hands of experienced radiologists who are skillful with this modality, are sensitive for the detection of acute PE in central pulmonary arteries, but have a low sensitivity for the detection of PE limited to subsegmental pulmonary arteries. The potential for CT to diagnose PE, therefore, is partially dependent on the prevalence of PE limited to subsegmental pulmonary arteries. Data are from the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). The largest pulmonary arteries that showed PE, as interpreted by the PIOPED angiographic readers, were identified in 375 patients in PIOPED with angiographically diagnosed PE. Among all patients with PE, 6% (95% confidence interval [CI], 4 to 9%) had PE limited to subsegmental branches of the pulmonary artery. Patients with high-probability ventilation/ perfusion (V/Q) scans had PE limited to subsegmental branches in only 1% (95% CI, 0 to 4%). Among patients with low-probability V/Q lung scans, 17% (95% CI, 8 to 29%) had PE limited to the subsegmental branches. Patients with low-probability V/Q scans and no prior cardiopulmonary disease had PE limited to the subsegmental pulmonary arteries in 30% (95% CI, 13 to 53%), whereas patients with low-probability V/Q scans who had prior cardiopulmonary disease had PE limited to subsegmental pulmonary arteries in 8% (95% CI, 2 to 22%) (p < 0.05). Based on data from all patients with PE in PIOPED, the prevalence of PE limited to subsegmental pulmonary arteries is low, 6%. PE limited to subsegmental pulmonary arteries was most prevalent among patients with low-probability V/Q scans, particularly if they had no prior cardiopulmonary disease.

Arterial Blood Gas Analysis in the Assessment of Suspected Acute Pulmonary Embolism

The utility of arterial blood gas levels in excluding the diagnosis of acute pulmonary embolism (PE) was evaluated. Data are from the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). PE was diagnosed or excluded by pulmonary angiography. Among 330 patients with no prior cardiopulmonary disease, 130 patients had PE and 200 did not. Among 438 patients with prior cardiopulmonary disease, 147 had PE and 291 did not. Definitions were low PaO2 (< 80 mm Hg), low PaCO2 (< 35 mm Hg), and high alveolar-arterial oxygen gradient (P(A-a)O2 [> 20 mm Hg]). Among patients with no prior cardiopulmonary disease who had values of the PaO2 and PaCO2 that were not low and a P(A-a)O2 that was normal, 16 of 42 or 38% (95% confidence interval [CI] = 24 to 54%) had PE. Among patients with prior cardiopulmonary disease who had PaO2 and PaCO2 values that were not low and a P(A-a)O2 that was normal, 4 of 28 or 14% (95% CI = 4 to 33%) had PE. Other combinations of blood gas levels and the P(A-a)O2 gradient, failed to exclude PE in larger percentages of patients. With various combinations of the PaO2 of 80 mm Hg or more, the PaCO2 of 35 mm Hg or higher, and the P(A-a)O2 gradient of 20 mm Hg or less, PE could not be excluded in more than 30% of patients with no prior cardiopulmonary disease and PE could not be excluded in more than 14% of patients with prior cardiopulmonary disease. Blood gas levels, therefore, are of insufficient discriminant value to permit exclusion of the diagnosis of PE.

Alveolar-Arterial Oxygen Gradient in the Assessment of Acute Pulmonary Embolism

The purpose of this investigation is to evaluate the utility of the alveolar-arterial (A-a) oxygen gradient in the diagnosis of acute pulmonary embolism (PE) among patients who participated in the Prospective Investigation of Pulmonary Embolism Diagnosis (PIO-PED). Pulmonary embolism was diagnosed (n = 280) or excluded (n = 499) by angiography in all patients. Patients were then categorized as (1) the entire cohort, (2) no prior cardiopulmonary disease and no prior PE, and (3) no prior PE or deep venous thrombosis. Normal values of the A-a gradient were defined in three ways: (1) values < or = 20 mm Hg; (2) values < or = age/4 + 4; and (3) values based on age from the literature. When a normal A-a gradient was defined as < or = 20 mmHg, 11 to 14% of patients with PE in the three categories of patients had a normal A-a gradient. When the equation age/4 + 4 was used, 8% to 10% of patients with PE in the three categories of patients had a normal A-a gradient. With age-related values from the literature, 20 to 23% of patients with PE in the three categories of patients had a normal A-a gradient. The A-a gradient was normal in comparable percentages of patients who did not have PE. Normal values of the A-a gradient did not exclude the diagnosis of acute PE.

Acute pulmonary embolism

Acute pulmonary embolism

Stratification of Patients According to Prior Cardiopulmonary Disease and Probability Assessment Based on the Number of Mismatched Segmental Equivalent Perfusion Defects: Approaches to Strengthen the Diagnostic Value off Ventilation/Perfusion Lung Scans in Acute Pulmonary Embolism

A categorical diagnosis of "high probability" or "intermediate probability" encompasses a spectrum of diagnostic probabilities of pulmonary embolism (PE) that is not communicated to the referring physician. The diagnostic value of ventilation/perfusion lung scans, in the present investigation, was strengthened by use of a table to determine the likelihood of PE in individual patients on the basis of the observed number of mismatched segmental equivalent perfusion defects. In addition, we tested the hypothesis that stratification of patients according to the presence or absence of prior cardiopulmonary disease may enhance the ventilation/perfusion scan assessment of the probability of PE among both of these clinical categories of patients. Data were derived from the collaborative study of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED). Ventilation/perfusion lung scans were evaluated in 378 patients with acute PE and 672 patients in whom suspected PE was excluded. Among patients with no prior cardiopulmonary disease, > or = 1.0 mismatched segmental equivalents was indicative of PE in 102 of 118 (86 percent) vs 113 of 155 (73 percent) among patients with prior cardiopulmonary disease (p < 0.02). Among patients with prior cardiopulmonary disease, > or = 2 mismatched segmental equivalents were required to indicate > or = 80 percent probability of PE. Stratification on the basis of the presence or absence of prior cardiopulmonary disease, therefore, enhanced the ability of ventilation/perfusion scan readers to assign an accurate positive predictive value and specificity to individual patients based on the observed number of mismatched segmental equivalent defects. Among patients with no prior cardiopulmonary disease, fewer mismatched segmental equivalent defects were required to indicate a high probability of PE than were required by PIOPED criteria. The findings from some of these patients, by PIOPED criteria, would have indicated intermediate probability. Some indeterminate probability readings, therefore, will be eliminated among patients stratified with no prior cardiopulmonary disease.

The Addition of Clinical Assessment to Stratification According to Prior Cardiopulmonary Disease Further Optimizes the Interpretation of Ventilation/Perfusion Lung Scans in Pulmonary Embolism

The purpose of this investigation was to test the hypothesis that prior clinical assessment among patients stratified according to the presence or absence of prior cardiopulmonary disease enhances the accuracy of the predictive value of pulmonary embolism (PE) in the various categories. Diagnostic evaluation was made on the cumulative spectrum of mismatched defects, rather than a probability based on a preassigned number of mismatched segmental equivalent defects or mismatched vascular defects. Families of curves were derived that allowed an accurate assessment of the predictive value for each category of patients. The families of curves were comparable, irrespective of whether ventilation/perfusion scans were assessed on the basis of mismatched segmental equivalent defects or mismatched vascular defects, although the latter eliminated the necessity of estimating whether segmental defects were large or moderate in size. Clinical assessment was shown to prominently affect the predictive value of PE. Prior clinical assessment among patients stratified according to prior cardiopulmonary disease enhanced the accuracy of the predictive value of PE in the various groups of patients.

Mismatched Vascular Defects: An Easy Alternative to Mismatched Segmental Equivalent Defects for the Interpretation of Ventilation/Perfusion Lung Scans in Pulmonary Embolism

The purpose of this investigation was to test the hypothesis that ventilation/perfusion (V/Q) lung scans in patients with suspected acute pulmonary embolism (PE) can be evaluated on the basis of the total number of mismatched vascular defects, irrespective of whether such defects are moderate or large size segmental defects. Lung scan data from the national collaborative study of the Prospective Investigation of Pulmonary Embolism Diagnosis (PIOPED) were assessed in 383 patients with acute PE and 681 patients in whom suspected PE was excluded. The predictive value of the cumulative number of mismatched moderate size segmental defects (irrespective of the number of mismatched large segmental defects) was nearly the same as that of mismatched large segmental defects (irrespective of the number of mismatched moderate size segmental defects). This suggests that the diagnostic value of mismatched moderate size segmental defects is the same as mismatched large segmental defects. Lung scans evaluated on the basis of the number of mismatched vascular defects (moderate and/or large segmental defects) were compared with V/Q scans evaluated on the basis of the number of mismatched segmental equivalents. The maximum likelihood estimates of the areas under the receiver operating characteristic (ROC) curves for the number of mismatched vascular defects and for mismatched segmental equivalents were similar (0.8512 vs 0.8530) (NS). Stratification according to the presence or absence of prior cardiopulmonary disease permitted a more accurate assessment of both clinical groups. Evaluation of V/Q scans by vascular defects and by segmental equivalents showed similar areas under the ROC curves. In conclusion, the number of mismatched vascular defects is as powerful for the assessment of V/Q scans as the number of mismatched segmental equivalents. The number of mismatched vascular defects, however, is easier to interpret, and permits a more objective evaluation.

Preexisting Cardiopulmonary Disease Attenuating the Atrial Natriuretic Peptide Response: Results in Patients with Acute Respiratory Failure

The purpose of this study was to evaluate the pathophysiologic role of atrial natriuretic peptide (ANP) as a pulmonary artery vasodilator in patients with acute respiratory failure receiving artificial ventilation. Twenty-one consecutive patients were studied, 12 without and 9 with preexisting cardiopulmonary disease. Pulmonary artery plasma ANP levels were significantly higher than the levels obtained in the superior vena cava and radial artery. Plasma ANP levels correlated significantly with the plasma levels of its second messenger, guanosine 3',5'-cyclic monophosphate (cGMP). In the 12 patients without prior cardiopulmonary disease, plasma ANP levels correlated significantly with mean pulmonary arterial pressure (MPAP). This correlation was not found in the nine patients with preexisting cardiopulmonary disease. The cGMP/ANP ratio, indicating the biologic effect of ANP, was also higher in the patients without preexisting cardiopulmonary disease. These results are compatible with clearance and vasodilator activity of ANP in the pulmonary vascular bed, but only in patients without preexisting cardiopulmonary disease.