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Biomedical subjects

P Leger

Publications and source records attributed to P Leger.

At least 91 records · Page 5Linked to original sources

Home positive pressure ventilation via nasal mask for patients with neuromusculoskeletal disorders.

29 patients with chronic respiratory failure due to neuromuscular deficits and restrictive chest wall disorders were treated with nocturnal ventilation via nasal mask at home for at least one year. Home ventilation was provided by a volume cycled positive pressure ventilator attached to a nasal mask which was made to measure by modelling silicon paste onto the patient's face. This method was well tolerated. The majority of the symptoms of hypoventilation rapidly disappeared with nocturnal ventilation and the daytime PaO2 and PaCO2 improved significantly allowing the patients to perform more daily activities. Nocturnal nasal ventilation is efficient but needs strict supervision. The nasal mask can replace or postpone tracheostomy which, if needed, remains a possible and efficient method.

Blood Gas Analysis↗

Hemodynamic characteristics of the Jarvik-7 total artificial heart.

To identify the optimal means of artificial circulation, driving controls and resultant hemodynamics were correlated with clinical outcomes in 37 Jarvik-7 recipients up to 72 hours after implantation. When patients with subsequent transplantation (n = 16) were compared with those who died on the Jarvik-7 heart (n = 21), there were no significant differences in total artificial heart driving mode such as frequency, ventricular driving pressures, systolic-diastolic ratio, or vacuum use, nor were there any differences in the hemodynamics achieved, such as device output (cardiac output) or atrial filling pressures, throughout the observation. However, improvements of other organ functions, especially kidney and liver, were remarkable in that transplant patients immediately experienced increased urine output and reversal of secondary organ dysfunction. The nontransplant group failed to diurese and continued to deteriorate despite similar hemodynamics. When a smaller model of the Jarvik-7 (volume of 70 ml, n = 18) was compared with the standard model (volume of 100 ml, n = 19), again there were no significant differences except that ventricular stroke volume was consistently less for the 70-ml model. Because of a slightly higher heart rate in the smaller model, device output did not differ between recipients of the two types. The results suggest that once successfully implanted, the Jarvik-7 provides adequate perfusion without associated mortality from circulatory failure, regardless of the size of the ventricle. Recovery from other organ failure appears to be independent of postimplant hemodynamics, a phenomenon that suggests the importance of preimplant status and patient selection.

Adult↗

Cardiac transplant recipients with preoperative pulmonary hypertension. Evolution of pulmonary hemodynamics and surgical options.

Among 48 consecutive patients with pretransplant pulmonary vascular resistance (PVR) greater than 4 Wood units, 38 patients underwent orthotopic heart replacement (OHT), and the remaining 10 received a graft in a heterotopic position (HHT). The OHT recipients were smaller (63 vs. 73 kg, p less than 0.05) and received a larger donor heart (donor-recipient, 109% vs. 79%, p less than 0.001) with a shorter graft ischemic time (108 vs. 139 minutes, p less than 0.05) than HHT recipients, reflecting patient selection and surgical complexity. Comparison between the hospital survivors and nonsurvivors identified the selection of HHT and graft ischemic time in excess of 150 minutes as potent risk factors. Immediately after transplantation, pulmonary artery (PA) pressures dropped to almost one half of preoperative values regardless of the mode of transplantation. Within the next 24 hours, however, the OHT group required lower doses of inotropes, had lower left atrial pressure (12 vs. 16 mm Hg, p less than 0.05), and were more frequently extubated (58% vs. 10%, p less than 0.01). Catheterization at 10 days revealed a doubled cardiac index and a dramatic reduction in PVR for both groups. The higher the preoperative PVR value, the more substantial the reduction observed, resulting in normalization of PVR for all survivors. The incidence of early graft failure was similar between the groups, but HHT recipients frequently developed pulmonary complications and infection, resulting in a 30% hospital survival in contrast to 71% in OHT recipients (p less than 0.05). The results suggest that transplant candidates with pulmonary hypertension might better be treated by OHT with an oversized, on-site, viable donor heart than by HHT.

Adult↗

Factors affecting survival after heterotopic heart transplantation.

In an attempt to identify the factors that influence survival after heterotopic heart transplantation, 42 consecutive recipients of heterotopic heart transplant were reviewed. Preoperative pulmonary artery pressures, pulmonary vascular resistance, and donor age significantly differed between hospital survivors and nonsurvivors. Postoperative survival analysis between pairs of groups of patients divided by each of these variables disclosed a significant difference, which confirmed the effects of these variables on survival. Evolution of pulmonary hemodynamics was compared between patients with preoperative pulmonary artery diastolic pressure greater than 25 mm Hg (pulmonary hypertension; n = 22) or less than 25 mm Hg (nonpulmonary hypertension; n = 20). Despite marked differences in preoperative pulmonary hemodynamics, pulmonary artery pressures were dramatically reduced immediately after transplantation, and pulmonary vascular resistance diminished to upper normal limits at 10 days when there were no longer differences in pulmonary vascular resistance between the two groups. Immediate deaths were related to left ventricular failure, and the incidence was similar between the groups. Despite such normalization of pulmonary hemodynamics, patients with preoperative pulmonary hypertension experienced more frequent ventricular fibrillation, required longer respiratory support, and developed lethal pulmonary or systemic infection, which resulted in a 32% (7/22) hospital survival rate compared with 90% (18/20) in patients without pulmonary hypertension. Despite the dramatic improvement in pulmonary hemodynamics, heterotopic heart failed to demonstrate the expected advantages because of frequent pulmonary complications and infection, which resulted in failure to improve the prognosis of patients with preoperative pulmonary hypertension.

Actuarial Analysis↗

Plasma concentrations of atrial natriuretic peptide in patients with artificial and transplanted hearts.

Plasma atrial natriuretic peptide (ANP) concentrations were measured by radioimmunoassay 1 to 12 days after operation in six patients with artificial hearts. The mean levels were significantly higher in artificial heart recipients (58.2 pg.ml-1) than in controls (12.6 pg.ml-1). The mechanism underlying the raised values is not clear, although it is suggested that elevated atrial pressure may have been the stimulus for higher ANP release. In 3 patients plasma ANP concentrations were also measured 1 to 5 days after orthotopic transplantation. In all of them ANP concentrations had increased by 20 to 74% despite lower right atrial pressure. An increase in atrial tissue mass may have contributed to the raised plasma ANP after orthotopic transplantation. It also suggests that the functioning sympathetic nervous system is not a necessary condition for ANP release.

Adult↗

Clinical application and patient selection in the use of a total artificial heart as a bridge for transplantation.

Between April 1986 and July 1987, 21 patients underwent orthotopic implantation of a total artificial heart (Jarvik 7) at La Pitié Hospital. There were 18 men and 3 women with a mean age of 37.3 +/- 11.4 years. The device implanted was the 70 ml version in 10 patients and the 100 ml version in 11 patients. In the results, three variables were analysed: age, acute myocardial decompensation or chronic myocardial failure, and aetiology of the 21 patients treated. 10 (47.6%) had adequate support and were successfully transplanted. Eleven patients (52.4%) died during circulatory support. The main causes of death were sepsis and multiple organ failure. In only one patient was a mismatch between the heart and chest cavity present. There was no clinical evidence of thromboembolic complications. Patients of 40 years of age and less have an 80% chance of being successfully transplanted in comparison with a 25% success rate in older patients. Patients that developed sudden cardiac decompensation have a 75% success rate for transplantation in comparison with 44.4% success rate in patients with a chronic illness. Early implantation of the device, before the development of irreversible damage in other organs, is recommended in younger patients with acute or chronic disease and in older patients with acute myocardial failure. The use of this device is contraindicated in immunosuppressed patients due to the high risk of infection.

Adult↗

[Heart-lung transplantation].

In this study the transplantation group of La Pitié Hospital, Paris, review heart-lung transplantation on the basis of data from the literature and of their own experience. Successively, the history, indications, pre-operative evaluation, donor selection, operative procedure with its immediate, mid-term and late complications, as well as treatment and post-operative follow-up are described.

Heart Transplantation↗

[An abdominal approach above the liver to the inferior vena cava].

The inferior vena cava (IVC) can be approached abdominally above the liver, either below the diaphragm, or in the fibrous pericardium, or in the serous pericardium. These techniques are described and discussed, as is the venous clamping upstream, always essential. Although rarely used, these procedures should be known by all surgeons.

Constriction↗