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Biomedical subjects

R C Daly

Publications and source records attributed to R C Daly.

At least 55 records · Page 3Linked to original sources
PubMed1997

Effect of pump flow rate on cerebral blood flow during hypothermic cardiopulmonary bypass in adults.

OBJECTIVE: The purpose of this study was to examine the effect of cardiopulmonary bypass flow rate on cerebral blood flow and cerebral metabolic rate for oxygen during hypothermic (27 degrees C) cardiopulmonary bypass. DESIGN, SETTING, AND PARTICIPANTS: The investigation was a prospective, randomized study in a tertiary care hospital setting. The 30 participants were volunteer adult cardiac surgical patients at a single institution. INTERVENTIONS: The N2O saturation method of Kety and Schmidt was used to determine global cerebral blood flow and metabolic rate during four periods: prebypass, cardiopulmonary bypass (CPB) (27 degrees C) flow rates of 2.3 and 1.2 L/min/m2, and 30 minutes post-CPB. Anesthesia consisted of fentanyl and midazolam; pH management was alpha-stat, and mean arterial pressure was maintained at 50 to 70 mmHg throughout CPB. MEASUREMENTS AND MAIN RESULTS: In the context of an unchanged mean arterial pressure, the pump flow did not affect cerebral blood flow or metabolic rate during hypothermic CPB. Systemic venous oxygen saturation was also maintained during reduced flow at 27 degrees C. Hemodilution during hypothermic CPB maintained cerebral blood flow at prebypass levels. In the postbypass period, persistent hemodilution resulted in an elevated cerebral blood flow. CONCLUSIONS: Brain oxygenation is well maintained at lower than conventional pump flow levels during CPB. There may be practical advantages to reduced flows during hypothermia, and flow reductions do not appear to adversely affect cerebral blood flow or metabolism.

Adult↗
PubMed1997

The effects of pulsatile cardiopulmonary bypass on cerebral and renal blood flow in dogs.

OBJECTIVE: The purpose of this study was to determine the effects of pulsatility on cerebral blood flow, cerebral metabolism, and renal blood flow over a range of cardiopulmonary bypass temperature and flow conditions. DESIGN/SETTING: The investigation was prospective, randomized, and performed in a canine physiology laboratory at the Mayo Foundation. PARTICIPANTS AND INTERVENTIONS: Anesthetized dogs were studied during pulsatile (n = 9) or nonpulsatile (n = 10) cardiopulmonary bypass at two flow rates (2.4 and 1.2 L/min/m2) at each of three temperatures (37 degrees, 32 degrees, and 27 degrees C). Pulsatility was achieved by use of a pediatric intraaortic balloon pump. Cerebral blood flow and metabolic rate were determined using the sagittal sinus outflow method. Renal blood flow was determined by a periarterial ultrasonic flow probe. MEASUREMENTS AND MAIN RESULTS: In the pulsatile group, a pulse pressure of 29 mmHg had no effect on cerebral blood flow or metabolism at any temperature under either flow condition. Renal blood flow was also unaffected by pulsatility, but decreased with hypothermia and reduced pump flow. Pulsatility also did not attenuate the systemic effects of normothermic hypoperfusion. CONCLUSIONS: Pulsatility has no significant effect on cerebral or renal perfusion over a broad range of cardiopulmonary bypass temperature and flow conditions. Cerebral blood flow and metabolism were functions of temperature but not pulsatility or flow rate. Renal blood flow was affected by both temperature and cardiopulmonary bypass flow rate but not by pulsatility. Finally, central nervous system perfusion may be preserved under low-flow cardiopulmonary bypass conditions by shunting of perfusion from splanchnic vascular beds.

Animals↗
PubMed1997

Surgical issues in lung transplantation: options, donor selection, graft preservation, and airway healing.

To present an overview of the surgical issues in lung transplantation, including the historical context and the rationale for choosing a particular procedure for a specific patient, we reviewed and summarized the current medical literature and our personal experience. Several surgical options are available, including single lung transplantation; double lung transplantation; heart-lung transplantation; bilateral, sequential single lung transplantation; and (recently) single lobe transplantation. Although single lung transplantation is preferred for maximal use of the available organs, bilateral lung transplantation is necessary for septic lung diseases and may be appropriate for pulmonary hypertension and bullous emphysema. Heart-lung transplantation is performed for Eisenmenger's syndrome and for primary pulmonary hypertension with severe right ventricular failure. General factors for consideration in assessment of compatibility of the donor and potential recipient include ABO blood group, height (the donor should be within +/- 20% of the recipient's height), and length of the lungs (determined on an anteroposterior chest roentgenogram). Graft preservation and minimal duration of ischemia are important. Complications associated with airway healing are related to ischemia of the donor bronchus. We have addressed the issue of donor bronchial ischemia by direct revascularization of the donor bronchial arteries with use of the recipient's internal thoracic artery. Currently, lung transplantation offers a realistic therapeutic option to patients with end-stage pulmonary parenchymal or vascular disease.

Graft Rejection↗
PubMed1997

Combined orthotopic heart and liver transplantation for genetic hemochromatosis.

A 47-year-old man with cirrhotic liver disease complicated by encephalopathy and class IV congestive heart failure caused by genetic hemochromatosis underwent combined orthotopic heart and liver transplantation. The patient remains well, working full time, 4 years after operation. Combined heart and liver transplantation is an effective therapy for selected patients with concurrent heart and liver failure caused by systemic iron overload.

Heart Failure↗
PubMed1996

DNA ploidy and protein content in bronchioloalveolar carcinoma multi-variable flow cytometry.

Multi-variable flow cytometry studies were done on paraffin-embedded surgical specimens from 97 patients with bronchiolalveolar carcinoma (BAC) and on 10 normal lung tissue specimens to assess the value of nuclear protein content besides DNA ploidy. Tumor tissues were stained for DNA content with propidium iodide and for protein content with fluorescein isothiocyanate. DNA ploidy measurements were successful in 87 of the 97 specimens. Twenty-four (28%) specimens were DNA diploid, and 63 (72%) were DNA nondiploid (DNA tetraploid or DNA aneuploid). There was no significant difference in survival between patients with DNA diploid and with DNA nondiploid tumors (P = 0.69). The protein histogram pattern was bimodal in 26/87 (30%) of patients; these had significantly shorter survival than patients with either normal or right-shift protein histogram patterns (61/87) (P = 0.0033). The nuclear protein measurement was an independent prognostic indicator when corrected for tumor grade and tumor size in a Cox model analysis (P = 0.04). The nuclear protein measurement correlated with nuclear size as determined by nuclear volume measurements. The combination of DNA ploidy, protein, and cell size measurements by flow cytometry provide a useful biologic basis for the variable prognosis seen with BAC tumors.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1996

Predictors of reversibility of pulmonary hypertension in cardiac transplant recipients in the first postoperative year.

BACKGROUND: Pulmonary hypertension remains a risk factor for early postoperative mortality in heart transplantation and may reduce the long-term benefits of the procedure. This study was undertaken to assess the value of baseline hemodynamic studies with nitroprusside used to predict the degree of postoperative reversibility of pulmonary hypertension in cardiac transplant recipients and to identify clinical risk factors for fixed pulmonary hypertension. METHODS AND RESULTS: Hemodynamic data from 55 consecutive patients who underwent orthotopic cardiac transplantation from June 1988 through September 1993 were analyzed. The effects of nitroprusside and transplantation on pulmonary artery pressure, cardiac output, and pulmonary vascular resistance were compared. Multiple regression analysis was used to identify the predictors of reversibility of pulmonary hypertension. Nitroprusside reduced pulmonary vascular resistance by increasing cardiac output and, to a lesser extent, by reducing the transpulmonary gradient. Pulmonary hypertension was less reversible in patients with ischemic heart disease (versus dilated cardiomyopathy) and in former smokers (versus nonsmokers). Patients with nonischemic heart failure and no smoking history had significantly lower posttransplant pulmonary vascular resistance (1.24 +/- 0.45 Wood units) than ischemic patients (who were all former smokers; 2.20 +/- 1.01 wood units) or nonischemic former smokers (1.72 +/- 0.70 Wood units). The correlation of pulmonary vascular resistance during nitroprusside challenge with posttransplant pulmonary vascular resistance was better than that of baseline pulmonary vascular resistance with posttransplant pulmonary vascular resistance. CONCLUSIONS: Nitroprusside testing improves the prediction of late posttransplant pulmonary vascular resistance; hence, it provides data that may be relevant to both early operative risk and later long-term effectiveness of cardiac transplantation. The finding of increased risk of fixed pulmonary hypertension associated with ischemic heart disease and smoking suggests that underlying atherosclerotic vascular disease may contribute to the irreversibility of pulmonary vascular resistance.

Adult↗
PubMed1996

Comparison of techniques for implantation of aortic valve allografts.

BACKGROUND: Various implantation techniques for allograft aortic valve replacement have evolved over the years. Our objective was to examine the effects of different implantation methods on subsequent valve performance and durability. METHODS: Between May 1985 and January 1994, 137 patients underwent allograft aortic valve replacement. The first 59 aortic valve allografts were inserted by the freehand scalloped technique with removal of the aortic sinuses, and the last 78 valves were inserted by the cylinder technique, in which the aortic sinuses and sinotubular junction were retained. The mean age of the 91 men and 46 women was 53.7 years (range, 18 to 83 years). Preoperative diagnoses were aortic stenosis (n = 57), aortic regurgitation (AR, n = 40) and aortic stenosis/AR (n = 40); 27 patients had prior aortic valve operations and 1 patient had a previous heart transplantation. Active endocarditis was present in 29 patients. Associated procedures included coronary artery bypass (n = 33), ascending aneurysm repair (n = 4), left ventricular aneurysmectomy (n = 3), repair of atrial septal defect (n = 2), mitral valve repair or replacement (n = 6), and aortic root enlargement (n = 24). Follow-up was complete in 133 patients (97%) a mean of 4.9 years (range, 1 day to 9.8 years) after allograft aortic valve replacement. RESULTS: Operative mortality was 6.5% for all patients but only 1.9% for patients without infection having isolated aortic valve replacement. Early echocardiography (mean of 8.4 days postoperatively) demonstrated no AR or mild AR and a mean gradient of 10.6 +/- 6.2 mm Hg in all patients. The cumulative risk of development of grade III or IV AR at 7 years postoperatively was 26.2% +/- 6.3% in the scallop group and 12.4% +/- 5.6% in the cylinder group (p = 0.4). Late postoperatively, transvalvular gradient by echocardiography was 13.1 +/- 9.4 mm Hg, and was similar in the two study groups. Late AR led to reoperation in 13 patients (22%) who had initial implantation with the scallop method and only 4 patients (5.4%) who had the valve inserted with the cylinder method. However, because duration of follow-up was longer for patients in the scallop group, cumulative risk of reoperation was similar at 5 years postoperatively (scallop, 13.7% [95% confidence interval, 76.7% to 95.8%]; cylinder, 11.5% [95% confidence interval, 75.5% to 99.1%]). CONCLUSIONS: The insertion of an aortic valve allograft as a cylinder, retaining the sinotubular junction, appears to result in less aortic regurgitation at 7 years postoperatively, and with additional follow-up may result in less reoperation for AR.

Adolescent↗
PubMed1996

Aortic valve replacement after previous coronary artery bypass grafting.

BACKGROUND: As the population ages, an increasing number of patients with previous coronary artery bypass grafting (CABG) will require subsequent aortic valve replacement (AVR). This study examined outcome of AVR after previous CABG and reviewed possible indications for valve replacement at the time of initial myocardial revascularization. METHODS: Between March 1975 and December 1994, 145 patients had AVR after previous CABG. Sixty-three patients (43%) had their initial CABG elsewhere. Reoperation for AVR was the second cardiac procedure in 137 patients and the third in 8. Redo CABG with AVR was done in 66 (46%). There were 118 men and 27 women. The mean age at CABG was 64 +/- 7.9 years; for AVR this was 71 +/- 7.6 years. RESULTS: In 2 young patients accelerated calcific aortic stenosis occurred in the setting of renal failure. Significant aortic stenosis did not appear to be addressed at initial CABG in 3 patients. Transaortic valvular gradient, as measured by cardiac catheterization, increased by 10.4 +/- 7.0 mm Hg/y. Twenty-four patients (16.6%) died. The mortality for AVR alone or for AVR + redo-CABG was 15 of 125 patients (12%). For patients having more complicated procedures, the mortality was 9 of 20 (45%). Nine patients (6.2%) suffered a postoperative cerebrovascular accident. Low preoperative ejection fraction measured by echocardiography, sternal reentry problems, complexity of operation, and prolonged cross-clamp and bypass times were significant factors associated with mortality. Age at AVR, interval between operations, the extent of underlying native coronary artery disease, the state of the previously placed bypass conduits, and methods of myocardial preservation were not significant predictors of operative mortality. On multivariate analysis there was only one significant value: prolonged cross-clamp time. CONCLUSIONS: Aortic valve replacement after previous CABG is associated with a mortality that is higher than that seen after repeat CABG or repeat AVR. It seems prudent, therefore, to use liberal criteria for AVR in those patients who require coronary revascularization and who, at the same time, have mild or moderate aortic valve disease.

Adult↗
PubMed1996

Aortic valve replacement in patients aged eighty years and older: early and long-term results.

UNLABELLED: We have studied 322 patients, 80 years of age or older, who underwent aortic valve replacement between June 1971 and December 1992. Two hundred six patients (64%) have had surgery since the end of 1985. Their mean age was 82.7 years (range 80 to 92 years). One hundred seventy-one (53%) were male and most (86%) were in New York Heart Association class III-IV. Fifty-seven patients (18%) required admission to the coronary care unit before the operation. One hundred seventy-nine patients (56%) underwent an urgent or emergency operation. Known cerebrovascular disease was present in 77 (24% of patients), aortic stenosis in 79%, aortic incompetence in 9%, and combined stenosis and incompetence in 12%. Associated procedures included bypass grafting in 139 (43%), mitral valve replacement/repair in 20 (6%), tricuspid valve repair in 6 (2%), and aortic annular enlargement in 38 (12%). Thirty patients (9.3%) were undergoing reoperation. Hospital mortality was 44 of 322 (13.7%). The median hospital stay was 11 days. On univariate analysis, significant predictors of hospital mortality were female sex, preoperative rest pain, New York Heart Association class III-IV, admission to the coronary care unit, heart failure, mitral valve disease, emergency/urgent operation, chronic obstructive pulmonary disease, bypass grafting, valve size, peripheral vascular disease, and ejection fraction less than 0.35. On multivariate analysis the most important independent predictors of operative mortality were female gender (p = 0.0001), renal impairment (p = 0.001), bypass grafting (p = 0.005), ejection fraction less than 0.35 (p = 0.01), and chronic obstructive pulmonary disease (p = 0.028). Age and year of operation did not influence mortality. Five-year survivals for all patients and for operative survivors were 60.2% +/- 3.2% and 70.3% +/- 3.4%, respectively. On univariate analysis, factors that adversely affected long-term survival were coronary bypass grafting (p = 0.007), more than two comorbidities (p = 0.02), male gender (p = 0.04), and ejection fraction less than 0.35 (p = 0.04). On multivariate analysis, no factor was consistently significant for long-term survival. At most recent clinical follow-up 85% were angina free and 82% were in class I-II. At least 92% of patients, both at 1 year and at most recent clinical follow-up, believed they had significantly benefited from the operation: CONCLUSION: Risk factors for aortic valve replacement in octogenarians include female gender, unstable symptoms, poor ejection fraction, renal impairment, and bypass grafting. However, despite a hospital mortality higher than that reported for younger patients, the outlook for operative survivors is excellent, with good relief of symptoms and an expected survival normal for this particular age group. If possible, aortic valve replacement should be done before development of unstable symptoms.

Age Factors↗
PubMed1996

Transmission of invasive aspergillosis from a subclinically infected donor to three different organ transplant recipients.

OBJECTIVE: To describe a cluster of donor-transmitted cases of invasive aspergillosis. DESIGN: Case series of epidemiologically linked cases of invasive aspergillosis. SETTING: Two tertiary care centers with solid-organ transplant programs. PATIENTS: Two kidney recipients, one heart recipient, and the single donor. MEASUREMENTS: Routine clinical, microbiological, and pathologic investigation as dictated for patient care. Epidemiologic analysis to establish linkage among cases. RESULTS: Three allografts (two kidneys and a heart) from a single donor transmitted invasive aspergillosis to the recipients. Three weeks after transplantation, the two kidney recipients had fever and urine cultures positive for Aspergillus fumigatus. The infected kidneys had multiple Aspergillus abscesses and had to be removed to cure the patients. The heart recipient had a negative workup when a diagnosis of aspergillosis was made for the kidney recipients but presented three months later with aspergillus endocarditis with hematogenous spread to the eyes and to the skin. Treatment included eye surgery, aortic valve replacement, and antifungal therapy; control of infection ensued. The donor was intensely immunosuppressed (17 days post-liver transplantation with death from intracerebral bleeding) but had no clinical or autopsy evidence of aspergillosis. Donor tracheal secretions obtained at the time of organ harvest later grew A fumigatus. CONCLUSION: Expanded criteria for organ donation have to be balanced against infectious risk to organ recipients. A fumigatus can be transmitted from a subclinically infected donor to solid-organ transplant recipients.

Abscess↗
PubMed1996

Genetic expression of endothelial nitric oxide synthase in human atrial myocardium.

OBJECTIVE: To investigate the expression of endothelial nitric oxide synthase (eNOS) in human cardiac tissues. DESIGN: We attempted to determine the genetic expression and localization of eNOS in normal human atrial tissue. MATERIAL AND METHODS: In normal human right atrial tissues from five donors during cardiac transplantation, eNOS expression and localization were assessed by using Northern blot analysis, in situ hybridization, and immunohistochemical staining. RESULTS: Northern blot analysis and in situ hybridization demonstrated that eNOS messenger RNA is present in cardiomyocytes. Positive immunohistochemical staining was observed in the cytoplasm of cardiomyocytes. CONCLUSION: These studies show for the first time the genetic expression and distribution of eNOS in human atrial myocardium and suggest that the eNOS mediated paracrine and autocrine pathway may participate in the control of myocardial function in humans.

Base Sequence↗
PubMed1996

Nurse manager learning styles in a learning environment.

This study focused on the development of guidelines for a training program for nurse managers in a newly formed integrated delivery system. Subjects' learning styles as defined in Kolb's Experimental Learning Theory were identified and graphically plotted in the appropriate learning environment or domain. Necessary training methods derived from Fry's Learning Environment table were applied to scores. A logical method is presented linking previous nursing student learning style studies with a cognitive schema experiment conducted with nursing novices and experts. The hypothesis that a subtle transition of learning style does occur from the concrete-divergent to the abstract-convergent as the nurse manager gains in education and moves through the management experience was supported.

Education, Nursing, Continuing↗
PubMed1995

Time to reperfusion and other procedural characteristics of emergency coronary artery bypass surgery after unsuccessful coronary angioplasty.

A databank search was performed and 148 consecutive patients (mean age 59.5 +/- 10.4 years) were identified who underwent emergency coronary artery bypass surgery at the Mayo Clinic between November 20, 1979, and February 12, 1992, immediately after unsuccessful coronary angioplasty. At the end of the angioplasty procedure, there was no anterograde coronary blood flow in the treated artery in 54%, ongoing chest pain in 78%, and hemodynamic compromise requiring intravenous vasopressor therapy in 25% of patients; 127 patients (86%) had at least 1 of these adverse characteristics. After leaving the catheterization laboratory, the median time to arrival in the operating room was 12 minutes. Median time from arrival in the operating room to initiation of cardiopulmonary bypass was 86 minutes, to administration of cardioplegia was 98 minutes, and to removal of the aortic cross-clamp was 135 minutes. In-hospital mortality was 11%, and 18% developed nonfatal Q-wave myocardial infarction. Thus, significant time is required to achieve surgical reperfusion after unsuccessful coronary angioplasty.

Aged↗
PubMed1995

Cerebral blood flow during cardiac operations: comparison of Kety-Schmidt and xenon-133 clearance methods.

This study simultaneously compared the standard Kety-Schmidt and the modified xenon-133 (133Xe) clearance techniques for measuring cerebral blood flow (CBF) and cerebral metabolic rate for oxygen (CMRO2) during cardiac operations. The validity of the CBF method is important because our management of the patient during cardiopulmonary bypass (CPB) is based, in part, on our understanding of the cerebral hemodynamics during CPB. In 20 patients undergoing coronary artery bypass grafting, CBF and CMRO2 were determined by both methods. Measurements were made before onset of CPB and once during CPB. Ten patients underwent CPB with systemic normothermia (37 degrees C) and 10 with systemic hypothermia (27 degrees C). Anesthesia consisted of fentanyl and midazolam. CPB pump flows were kept at 2.2 to 2.4 L.min-1.m-2 and alpha-stat pH management was used. Xenon-133 clearance significantly underestimated CBF and CMRO2 relative to the Kety-Schmidt technique before CPB and at both bypass temperatures. Values obtained by 133Xe clearance were approximately 50% of that measured by the Kety-Schmidt method. The modified 133Xe technique as typically used during cardiac operations does not appear to measure CBF accurately; this leads to corresponding errors in CMRO2 calculations. Determination of CMRO2 and cerebral autoregulatory function during cardiac operations appears to be more appropriate if based on the more direct Kety-Schmidt technique. Accordingly, our management of CPB with respect to cerebral perfusion as it has been determined by the modified 133Xe clearance method may require reassessment.

Blood Gas Analysis↗