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Biomedical subjects

J F Lewis

Publications and source records attributed to J F Lewis.

At least 91 records · Page 5Linked to original sources

Hypophosphatemia and respiratory failure: prolonged abnormal energy metabolism demonstrated by nuclear magnetic resonance spectroscopy.

Hypophosphatemia has been shown to cause acute respiratory failure. The mechanism is believed to be due to decreased high-energy substrate availability at the cellular level leading to respiratory muscle dysfunction. However, direct measurement of these substrates has not been previously studied. A patient with hypophosphatemic respiratory failure is described in whom phosphocreatine and pH were continuously monitored using nuclear magnetic resonance spectroscopy. This revealed a defect in muscle metabolism that required several weeks to recover despite prompt correction of the serum phosphate level.

Acute Disease↗

Tricuspid stenosis in prosthetic valve endocarditis. Diagnosis by Doppler echocardiography.

Valvular stenosis is an uncommon finding in bacterial endocarditis involving native cardiac valves. Prosthetic valve endocarditis, however, is more commonly associated with obstruction. Bioprosthetic cardiac valves may be particularly prone to this complication. A case of bioprosthetic tricuspid valve endocarditis with stenosis diagnosed by Doppler echocardiography and confirmed by operative findings is presented.

Adult↗

Effects of transluminal coronary angioplasty on left ventricular systolic and diastolic function at rest and during exercise.

The left ventricular global and regional systolic function, ventricular volumes, and peak diastolic filling rate (PDFR) were studied in 30 patients with coronary artery disease, before and 2 to 5 days after transluminal coronary angioplasty (PTCA), utilizing equilibrium radionuclide angiography at rest and during exercise. At rest, the global ejection fraction (EF) was unchanged before (60 +/- 9%) and after PTCA (62 +/- 10%). During exercise, global EF increased from 59 +/- 11% pre PTCA to 67 +/- 10 post PTCA (p less than 0.001). Twenty-two patients had abnormal EF response to exercise pre PTCA, versus seven post PTCA (p less than 0.001). Improvements in exercise regional EF paralleled the changes in global EF. End-systolic volume was unchanged at rest but decreased significantly with exercise post PTCA (60 +/- 36 ml pre vs 49 +/- 32 ml post PTCA, p less than 0.01). At rest, the PDFR was unchanged post PTCA (2.4 +/- 0.9 end-diastolic volume (EDV)/sec pre vs 2.5 +/- 0.8 EDV/sec post). During exercise, PDFR increased from 2.1 +/- 0.7 EDV/sec pre PTCA to 2.5 +/- 0.7 EDV/sec post PTCA (p less than 0.02). In conclusion, in patients with coronary artery disease, successful PTCA improves global and regional systolic function during exercise. Diastolic function is improved during exercise, a fact not previously demonstrated.

Adult↗

Pulsed Doppler echocardiographic determination of stroke volume and cardiac output: clinical validation of two new methods using the apical window.

Two methods of measuring stroke volume and cardiac output with pulsed Doppler two-dimensional echocardiography were developed and validated against the thermodilution technique in 39 patients, 33 of which were in an intensive care unit. With the use of the apical four-chamber view, a mitral inflow method combined the velocity of left ventricular inflow at the mitral anulus with the cross-sectional area of the anulus calculated from its diameter at middiastole (area = pi r2). From the apical five-chamber view a left ventricular outflow method combined the velocity of left ventricular outflow with the cross-sectional area of the aortic anulus calculated from its diameter during early systole (parasternal long-axis view). Measurements with the mitral inflow and left ventricular outflow methods were obtained in 35 of 39 (90%) and 39 of 39 (100%) patients, respectively. Validation of the mitral method excluded patients with mitral regurgitation (n = 11) and validation of the left ventricular outflow method excluded those with aortic regurgitation (n = 4). Good correlations were observed between thermodilution and Doppler measurements of stroke volume and cardiac output for both the mitral anulus method (R = .96 and .87, respectively) and the left ventricular outflow method (R = .95 and .91, respectively). The results of the two methods correlated well with each other in patients without regurgitant valve lesions. A greater interobserver variability was observed with the mitral anulus method, which was related solely to greater variability in measuring the annular diameter.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

Evaluation of API 20E strips for identification of coagulase-negative staphylococci from the urinary tract.

A previous study indicated that the API 230E system can identify coagulase-negative Staphylococcus species. A study was devised to evaluate the use of the API 20E system for this purpose. Because of the current interest in Staphylococcus saprophyticus the relationship of the API 20E results to novobiocin susceptibility was also examined. One hundred forty-nine isolates of coagulase-negative staphylococci from urine cultures were tested with the API 20E system. The identification of 49 isolates was confirmed by Kloos and Schleifer method. We found that the routine API 20E system did not provide more information than novobiocin susceptibility studies alone, and that there was good but not absolute correlation between novobiocin resistance and identification of S. saprophyticus.

Bacteriological Techniques↗

Urinary tract infection due to coagulase-negative staphylococcus.

One hundred and fifty-six urine specimens with a pure culture of coagulase-negative Staphylococcus were studied. One hundred and eighteen charts were reviewed for clinical evidence of urinary tract infections. Twenty-four cases of urinary tract infection were found. The younger females in the study tended to have infection due to novobiocin resistant Staphylococcus in contrast to males and older females.

Adolescent↗

Blood cultures in bacteremia.

Blood cultures in a 700-bed hospital were examined for clinical relevance. During a six-month period 5,154 blood samples were drawn from 1,091 patients. Of the 124 patients with positive blood cultures, 7% had polymicrobic isolates. A review of hospital records for a three-year period revealed 162 charts with adequate documentation for evaluation of bacteremia. An additional 11 charts were found with inappropriately negative blood cultures. Fifteen percent of these patients were found to have polymicrobic isolates. The importance of establishing guidelines and criteria concerning acceptable blood culture practices is detailed.

Bacteria↗

Overnight refrigeration of urine specimens for culture.

Some authorities state that urine may be refrigerated overnight and still be satisfactory for quantitative bacteriologic evaluation. The papers cited appear to us to be inadequate. Four hundred and fourteen urine cultures were evaluated comparing colony count before and after overnight refrigeration. Overnight refrigeration appears to be a satisfactory means of urine preservation for culture.

Humans↗

Isolation and evaluation of clostridia from clinical sources.

During a two-year period, 133 isolates of clostridia from clinical courses were obtained. These isolates are reviewed as to clinical significance and antimicrobial susceptibility. Adequate charts were available on 63 patients, nine (14%) of whom had their clinical source significantly altered by the presence of clostridia. Clostridia of little or no clinical significance were isolated from blood cultures from six patients. The occurrence of clostridial infections is unpredictable, and adequate clinical information is necessary to determine the need for identification of clostridial isolates.

Clostridium↗

Operative experience with infective endocarditis and intracerebral mycotic aneurysm.

The surgical management of eight patients with infective endocarditis and intracerebral mycotic aneurysm is presented. Three patients had craniotomy before valve replacement and four patients had valve replacement before craniotomy. There were no deaths related to the valve replacement or craniotomy. Two of the eight patients died in the hospital of continuing sepsis resulting from undrained foci of infection. It is concluded that the drug-addicted patient with a mycotic aneurysm and hemodynamic decompensation from endocarditis can be successfully treated by staging the operations according to the more severe problem.

Adult↗

Evaluation of amniotic fluid for aerobic and anaerobic bacteria.

Studies of 117 pregnant women, 83 at term, were instituted to determine the bacteriologic state of amniotic fluid, utilizing both standard aerobic and anaerobic technics. A high association of postpartum infection was found in women who had long periods of premature reptured membranes and many vaginal examinations. Significant organisms including anaerobes, were isolated in many of these instances. Based on the findings of these studies, it is recommended that amniocentesis for aerobic and anaerobic cultures be done when membranes have been ruptured for 8 hours or more, and when the patient has had seven or more vaginal examinations during the course of labor.

Adolescent↗