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Biomedical subjects

R D Levy

Publications and source records attributed to R D Levy.

At least 73 records · Page 4Linked to original sources
PubMed1994

Wegener's granulomatosis and the heart.

Three cases of Wegener's granulomatosis with cardiac complications are described and the relevant published reports are reviewed. The first case of Wegener's granulomatosis was associated with aortic regurgitation and required aortic valve replacement. The second and third cases were associated with pericardial disease requiring pericardiectomy for constructive pericarditis in one case, and haemorrhagic pericarditis with pericardial effusion in the other. Aortic valve involvement in Wegener's granulomatosis is uncommon and valve replacement has been described on only one previous occasion. Pericardial involvement is relatively common pathologically, but pericardial surgery has been described in this condition only twice, once for tamponade and once for constrictive pericarditis after pericardiocentesis. Cardiac involvement is not uncommon in patients with Wegner's granulomatosis and may be clinically important. Diagnosis is aided by estimation of the anti-neutophil cytoplasmic antibody titre.

Adult↗
PubMed1994

Mechanisms of apnea termination in obstructive sleep apnea. Role of chemoreceptor and mechanoreceptor stimuli.

Previous work from our laboratory has indicated that mechanoreceptor feedback from the respiratory muscles may play an important role in arousal and apnea termination in obstructive sleep apnea (OSA). Other studies have pointed to a prominent role for chemoreceptor stimuli. We postulated that mechanoreceptor stimuli from the respiratory system are the primary determinant of apnea termination, and that chemoreceptor stimuli exert their effect indirectly through stimulation of ventilation and thus proprioceptive feedback. To test this, we measured the diaphragmatic tension-time index (TTdi) during obstructive sleep apneas in seven male subjects with severe untreated OSA. We compared the maximal TTdi values at end-apnea during administration of air, O2, and CO2. We reasoned that if mechanoreceptor stimuli mediate apnea termination, changing the degree of chemoreceptor stimulation during apneas should not alter the level of respiratory effort at end-apnea. O2 administration produced a significant increase in end-apneic arterial oxygen saturation (SaO2) and increased apnea duration. CO2 administration led to an increase in pre- and postapneic end-tidal carbon dioxide pressure (PETCO2), and tended to shorten apneas. However, the mean value for maximal end-apneic TTdi was 0.12 +/- 0.01 (SEM) during room air breathing and was unaltered by O2 (0.12 +/- 0.01) or CO2 (0.11 +/- 0.01) administration. The consistency of end-apneic TTdi values despite the varying chemical drive supports the hypothesis that apnea termination in OSA is mediated by mechanoreceptor feedback from the respiratory system, most likely from the respiratory muscles. The influence of chemoreceptor information may be mediated indirectly through an effect on ventilatory effort.

Adult↗
PubMed1994

Changes in obstructive sleep apnea characteristics through the night.

It was our impression that the respiratory parameters in obstructive sleep apnea (OSA) worsened as the night progressed. To confirm this, we review polysomnographic studies from 66 patients with apnea-hypopnea indices (AHI) of 40 to 125 events per hour, dividing bed time into equal quartiles. As the night progressed, the mean apnea duration (MAD) increased from 27.2 s to 34.6 s (p < 0.0001), mainly from increases during NREM sleep. The proportion of time spent in apnea increased from 54 to 71% (p < 0.0001) due to increases in both MAD and the proportion of REM sleep (from 2.8 to 14.7% of the total sleep time). The AHI did not change significantly between quartiles. Even though preapneic oxygen saturation did not change and apnea duration increased as the night progressed, the end-apneic saturation did not decrease, hence the rate of oxygen desaturation decreased. Also, it was found that patients with an AHI greater than 65 events per hour increased their proportion of time spent in apnea significantly more than those with an AHI smaller than 65, as the night progressed. In the patients with an AHI greater than 85, this was due to both an increase in MAD and AHI. In conclusion, in patients with an AHI greater than 40 events per hour, the severity of apnea increased as the night progressed due to lengthening of MAD, increased proportion of REM sleep, and in the most severe patients, also an increase in AHI. Even though the exact pathophysiologic mechanisms for the observed changes are unknown, a decrease in respiratory muscle effort with consequent decrease in oxygen consumption may explain both the lengthening of the apneas and the decrease in the rate of oxygen desaturation.

Apnea↗
PubMed1994

Stool weight and faecal pH in two South African populations with a dissimilar colon cancer risk.

Bowel diseases (appendicitis, diverticulitis and colon cancer) in South African whites and populations of prosperous Western countries are similar. Among rural South African blacks with a traditional lifestyle these diseases are very uncommon or almost unknown. A study was undertaken to measure stool weight and faecal pH in South African urban blacks and whites. There was no difference in stool weight, but the faecal pH was significantly higher in whites (P = 0.002).

Adult↗
PubMed1994

Penetrating injuries of the popliteal artery: the Baragwanath experience.

This study describes the management of 43 patients with penetrating injury of the popliteal artery. Of these patients, 33 (76.5%) had bullet wounds, four patients (9.5%) pellet wounds and 6 (14%) knife wounds. Patients with 'hard' signs of arterial injury underwent exploration without preoperative angiograms. There were no negative explorations. Patients with only 'soft' signs of arterial injury underwent preoperative angiograms. Of this group, 75% had positive angiograms and underwent exploration. There were no false-positive or false-negative preoperative angiograms in the group of patients with 'soft' signs in this study. Definitive orthopaedic management of associated fractures followed vascular reconstruction. There was no difference in the short-term patency of autologous saphenous vein graft as against PTFE grafts. Fasciotomy was performed on patients who had arterial and venous injury or presented late. Overall amputation rate was 14% and for bullet injuries 18%.

Adolescent↗
PubMed1994

Quality adjusted life years added by treatment of obstructive sleep apnea.

We assessed the impact of treatment with nasal continuous positive airway pressure (nCPAP) on the quality of life of 19 patients with obstructive sleep apnea (OSA). We measured the utility for the patients' health states before and with treatment using the standard gamble approach. The study group had an average age of 57 years and had been on treatment for a mean of 9.5 months. For all the patients, the polysomnographic indicators of OSA disease severity improved markedly with treatment. For nine of the 12 symptoms most commonly associated with OSA, the patients reported improvement during treatment. The mean utility and the standard deviation obtained with the standard gamble method were 0.87 +/- 0.17 on treatment and 0.63 +/- 0.29 pretreatment. The difference in utility between treatment and pretreatment health states was combined with the life expectancy of each patient to generate the number of quality adjusted life years (QALYs) considered equivalent to the impact of treatment. This resulted in an average gain of 5.4 QALYs. When we related this impact to the cost of treatment, we obtained a cost-utility ratio between Can $3,397 and Can $9,792 per QALY added. These costs are relatively small when compared to the cost per QALY for many other clinical interventions. Hence, nCPAP clearly offers the prospect for a well-tolerated therapy with a very favorable cost-utility ratio.

Adult↗
PubMed1993

Catheter ablation of the atrioventricular junction by radiofrequency energy delivered across the interventricular septum using a left sided approach.

We describe seven successful cases of ablation of the atrioventricular (AV) junction by passing radiofrequency (RF) energy between the tip of an electrode on the left ventricular aspect of the interventricular septum and a further electrode on the right side of the His bundle. All had undergone unsuccessful attempts at conventional unipolar RF ablation from the right and left side of the heart.

Aged↗
PubMed1993

Disseminated infection after intravesical BCG immunotherapy. Detection of organisms in pulmonary tissue.

A 57-year-old man undergoing intravesical immunotherapy with BCG for transitional cell bladder carcinoma presented with dyspnea, fever, hypoxemia, and a diffuse micronodular pattern on chest radiograph. Transbronchial biopsy specimen revealed widespread noncaseating granulomas, and acid-fast bacilli were identified in sputum as well as in the biopsy tissue. The patient's condition responded promptly to antituberculous antibiotics given in conjunction with corticosteroids. Although no growth was evident on TB culture of the specimens, the presence of organisms indicates a probable infectious cause of the pulmonary disease process.

Administration, Intravesical↗
PubMed1993

Relationship of resting lung mechanics and exercise pattern of breathing in patients with chronic obstructive lung disease.

To investigate the influence of resting pulmonary mechanics on the pattern of breathing during exercise in chronic obstructive pulmonary disease (COPD), we studied 29 patients with moderate to severe COPD (FEV1 50 +/- 20 percent predicted), and 10 normal subjects. Lung mechanics were studied using esophageal balloon technique and body-box. Incremental exercise testing was performed to exhaustion. As minute ventilation (VE) increases, COPD patients with the highest pulmonary resistance (RI) or lowest elastic recoil pressure (PL), used a greater tidal volume/vital capacity ratio (VT/VC) than the COPD patients with more normal RL or lowest PL. To describe the breathing pattern during exercise, an exponential constant (K) describes the rates of increase in VT/VC ratio with increasing VE, calculated according to the equation VT = VC(1-e-KVE). The K values achieved by COPD patients were higher than in normal subjects. In addition, K value correlated negatively with the resting FEV1 and FVC of COPD patients. When COPD patients were grouped according to their K values, it was revealed that patients with high K values generated greater VT/VC ratio and also have the most abnormal resting lung mechanics. These results suggest that the exercise breathing pattern in COPD patients is significantly influenced by the degree of impairment of resting lung mechanics.

Adult↗
PubMed1993

Prolonged survival after heart-lung transplantation in systemic lupus erythematosus.

Patients with multisystem involvement of connective tissue disorders are generally excluded from consideration for heart-lung and lung transplantation because of profound donor organ shortages. A 23-year-old woman with systemic lupus erythematosus (SLE) was referred for evaluation of severe, progressive pulmonary hypertension. She underwent an uneventful heart-lung transplant and received cyclosporine A, azathioprine, and prednisone on a long-term basis. Bronchiolitis obliterans resulted in the development of moderate airflow obstruction 18 months after transplantation, but the process was stabilized with augmented immunosuppression consisting of high-dose parenterally administered corticosteroids, and subsequently a course of antithymocyte globulin. Four years after transplant, despite the persistence of reduced complement levels, the patient remains functionally well without clinical manifestations of SLE. This patient's long-term successful outcome indicates that connective tissue disorders such as SLE do not necessarily represent absolute contraindications to heart-lung and lung transplantation.

Adult↗
PubMed1993

Intussusception of appendix with carcinoid tumour. A case report.

During an operation for suspected appendicitis, no appendix was found at the confluence of the caecal taeniae. A mobile mass in the caecum was explored and intussusception of the appendix was identified. Histological examination of the specimen revealed carcinoid of the appendix. The diagnosis and management of intussusception of the appendix are discussed.

Adult↗
PubMed1992

An audit of drug usage for in-hospital cardiopulmonary resuscitation.

The objective of this study was to assess the changes in outcome of cardiac arrest due to ventricular fibrillation, asystole and electromechanical dissociation in relation to the changing guidelines for drug therapy set by the U.K. Resuscitation Council. It was a retrospective study of 667 resuscitation records for the years 1982, 1986, 1988, 1989, 1990 and 1991. It took place in a large district general hospital with a regional cardio-thoracic centre. We have audited the asystolic cardiac arrests (N = 271) which occurred outside the cardiac care unit (CCU). Adrenaline (intravenous 1 mg) is now the first line drug followed by atropine at an increased dose (2 mg intravenously); calcium is no longer recommended and sodium bicarbonate should be reserved for cases in which an acidosis has been documented. Atropine use has increased over the 9-year period. Bicarbonate use did not change from 1982 to 1986 but fell progressively to no use at all in 1991. Calcium use has declined since 1982. Adrenaline use has remained unchanged. Survival from asystolic arrests (hospital discharge) has remained unchanged at 0-5.5%. Asystole as a primary event in the CCU was uncommon (N = 17) and no patient was discharged. Over the same period, 60% of patients (N = 92) with a cardiac arrest on CCU due to ventricular fibrillation (VF) were discharged and 55% were alive after 6 months. For VF on the wards (N = 192), only 20% of patients were discharged from hospital. A similar proportion was successful for each year.(ABSTRACT TRUNCATED AT 250 WORDS)

Atropine↗
PubMed1992

Failure of balloon dilatation of the pulmonary valve in carcinoid pulmonary stenosis.

BACKGROUND: Carcinoid heart disease typically results in pulmonary stenosis and tricuspid incompetence. Percutaneous balloon dilatation is an effective treatment for congenital pulmonary stenosis and has been applied successfully to tricuspid stenosis caused by carcinoid heart disease. The value of balloon dilatation of the pulmonary valve in carcinoid pulmonary stenosis was assessed. METHODS: Two patients with severe congestive heart failure secondary to carcinoid heart disease and with documented pulmonary stenosis had balloon dilatation of the pulmonary valve. In both cases tricuspid regurgitation was also present together with reduced cardiac output. RESULTS: The procedure was technically successful in both patients. One patient experienced symptomatic benefit for two months and the other experienced no improvement. Both patients subsequently required combined tricuspid and pulmonary valve replacement from which good results and symptomatic improvement were obtained. CONCLUSION: Though balloon dilatation of the pulmonary valve is technically feasible it is unlikely to provide useful palliation in carcinoid heart disease. Valve surgery should be considered in patients in whom the malignancy is controlled but carcinoid heart disease is producing drug resistant congestive heart failure.

Carcinoid Heart Disease↗