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Biomedical subjects

N J Sears

Publications and source records attributed to N J Sears.

7 recordsLinked to original sources
PubMed1995

Effect of prior sternotomy on mortality and morbidity after heart transplantation. Cardiac Transplant Team.

A retrospective analysis to evaluate the impact of prior sternotomy on the outcome of cardiac transplantation was undertaken. Some 165 patients who received primary heart transplantation were classified into three groups. There were 102 patients in group 1 (no prior sternotomy), 47 in group 2 (one prior sternotomy), and 16 in group 3 (more than one prior sternotomy). The three groups were demographically similar. Coronary artery bypass was the indication for prior sternotomy in 77% of patients in group 2 and in 94% in group 3. Mortality within 30 days post-transplant was significantly different among the three groups (group 1, 7.8%; group 2, 8.5%; group 3, 31%; P = 0.0148). The 1-year actuarial survival was also significantly lower in group 3 (52%) compared with groups 1 (83%) and 2 (81%) (P = 0.0311). Multivariate analysis identified more than one prior sternotomy and pulmonary hypertension as risk factors for death within 30 days post-transplant. Patients who had prior sternotomy also had a higher incidence of coagulopathy (group 1, 17%; group 2, 49%; group 3, 38%; P = 0.0002), and re-exploration due to excessive bleeding (group 1, 5%; group 2, 11%; group 3, 25%; P = 0.0225). Requirement for blood products for transfusion was also higher in groups 2 and 3. There was no significant difference among the three groups in the incidence of early infections (50% versus 53% versus 44%), renal failure (6% versus 11% versus 19%), or allograft rejection in patients who survived the first 30 days (95% versus 86% versus 82%).(ABSTRACT TRUNCATED AT 250 WORDS)

Cause of Death↗
PubMed1991

Distribution of ventilation and perfusion with different modes of mechanical ventilation.

We compared pulmonary gas exchange during synchronized intermittent mandatory ventilation (SIMV), pressure support ventilation (PSV), and airway pressure release ventilation (APRV). Nine subjects aged 56 to 75 yr were studied from 4 to 19 h after cardiac operations. When subjects were ready to be weaned from mechanical ventilation their ventilation-perfusion distribution was estimated using the multiple inert gas elimination technique during SIMV. The subjects then received PSV and APRV during alternating periods on a randomized basis, and the gas-exchange measurements were repeated. Vasoactive infusions and inspired oxygen fraction were held constant throughout the investigation. The results indicated that the major characteristics of the main mode of the VA/Q distributions (mean, standard deviation, and skew) were similar during all three modes. Dead space was lower during APRV (30.1 +/- 1.7% [SEM]) than during SIMV (36.2 +/- 1.5%) and PSV (37.1 +/- 2.7%) (p less than 0.05). Right-to-left shunt was significantly greater during APRV (19.9 +/- 2.3%) than during SIMV (15.4 +/- 1.7%) (p less than 0.05). Peak airway pressure (Paw) was higher during SIMV (32.8 +/- 1.3 cm H2O) than both PSV (19.4 +/- 2.1 cm H2O) and APRV (14.3 +/- 1.0 cm H2O) (p less than 0.05). Minute ventilation was lower during APRV (7.5 +/- 0.07 L/min) than during SIMV (9.4 +/- 0.6 L/min) and PSV (9.0 +/- 0.5 L/min) (p less than 0.05). Hemodynamic variables were similar during all three modes. We conclude that all three modes provide acceptable oxygenation and ventilatory support.

Aged↗
PubMed1985

Metastatic mediastinal neoplasm masquerading as aortic dissection: a skip sign on computed tomography for their distinction.

Four years after undergoing a left lower lobe lobectomy for squamous cell carcinoma, a 77-year-old man presented with a mass lesion in the left upper mediastinum associated with chest pain. Computed tomography revealed a homogeneous density immediately adjacent to the aortic arch and thoracic aorta consistent with aortic dissection. Upon thoracotomy, however, the lesion was found to be an oat cell carcinoma. Retrospective review of the computed tomography scans detected a normal segment of descending aorta, indicating the interruption of the paraaortic lesion. Such a skip sign can be used to rule out aortic dissection.

Aged↗
PubMed1984

Venous prostheses: improved patency with external stents.

A uniformly successful prosthesis for replacement in the venous system has not been developed. This study assesses the effect of external stents on the patency of polytetrafluoroethylene (PTFE) grafts in the infrarenal vena cava. Under general anesthesia, 21 mongrel dogs underwent midline laparotomy. The infrarenal vena cava was resected and replaced by a standard segment (8 cm X 10 mm) of stented PTFE (12 dogs) and nonstented PTFE (9 dogs). Patency was assessed by contrast venography and the results compared between the two groups. The 7-, 30-, and 90-day patency was 12/12, 10/12, and 9/12, respectively, for stented PTFE and 6/9, 2/9, and 2/9, respectively, for nonstented PTFE. The patency of externally stented PTFE at 30 and 90 days was significantly better than grafts fashioned from PTFE alone (P less than 0.05 by chi-square analysis). These data demonstrate that external stenting improves the early patency of PTFE prostheses in the infrarenal vena cava. Consideration should be given to the clinical use of externally stented PTFE when prosthetic replacement in the venous system is required.

Animals↗
PubMed1983

The prevention of extra cardiac conduit obstruction: an experimental study.

Acquired right ventricular (RV) extracardiac conduit (ECC) obstruction was studied in an animal model. A 16 mm woven Dacron tube graft was inserted between the right ventricle (RV) and main pulmonary artery (PA) in 18 adult mongrel dogs followed by pulmonary artery occlusion with a Dacron tape. In 9 dogs, the RV anastomosis was maintained with a 16 mm Dacron covered polypropylene stent. The remaining 9 animals with direct suture attachment of the graft to the myocardium served as controls. Cardiac output and transconduit resistance were measured at operation, 6 months, and 1 year. The cardiac output remained the same in both groups. Animals with stented ECC showed little change in transconduit resistance and had a widely patent RV anastomosis at 1 year. Unstented conduits had increased transconduit resistance at 6 months and 1 year (P less than 0.002). Postmortem examination showed fibromuscular ingrowth of the ventricular anastomosis to be the site of the acquired obstruction in unstented extracardiac conduits. The inclusion of a rigid stent in RV-ECC may warrant clinical application to prevent fibromuscular ingrowth and late RV anastomotic obstruction.

Animals↗