Biomedical subjects

C Marcucci

Publications and source records attributed to C Marcucci.

7 recordsLinked to original sources

PubMed2005

[Perioperative blood transfusions. Value, risks, and guidelines].

Surgical blood loss and trauma are the major causes of allogeneic blood transfusions, which still bear considerable risks. After the correction of hypovolemia, the anesthesiologist often has to deal with normovolemic anemia. The clinical relevance of this isolated decrease in hemoglobin concentration consists in an eventually compromised global or regional oxygen supply with the development of tissue hypoxia below a critical threshold. This is an individual threshold for each patient and depends on his or her capacity to compensate the decrease in blood oxygen content. Therefore, physiologic transfusion triggers should primarily be applied and not rigid numeric transfusion triggers, such as hemoglobin concentration, which do not take into account each patient's individual reserve.

Adult↗

PubMed2004

Fatal myocardial infarction after lung resection in a patient with prophylactic preoperative coronary stenting.

In this report we present the case of a 77-yr-old man who underwent resection of the upper lobe of the left lung for a carcinoma, six weeks after percutaneous transluminal coronary angioplasty (PTCA) with stenting of the left anterior descending (LAD) and circumflex coronary arteries. Antiplatelet therapy with clopidogrel was interrupted two weeks before surgery to allow for epidural catheter placement and to minimize haemorrhage. The surgical procedure was uneventful. In the immediate postoperative period, however, the patient suffered severe myocardial ischaemia. Emergency coronary angiography showed complete thrombotic occlusion of the LAD stent. In spite of successful recanalization, reinfarction occurred and the patient died in cardiogenic shock. Prophylactic preoperative coronary stenting may put the patient at risk of stent thrombosis if surgery cannot be postponed for three months. In such cases, other strategies such as perioperative beta-blockade for preoperative cardiac management should be considered.

Aged↗

PubMed2001

Distribution of pulmonary ventilation using Xe-enhanced computed tomography in prone and supine dogs.

Xe-enhanced computed tomography (CT; Xe-CT) is a method for the noninvasive measurement of regional pulmonary ventilation in intact subjects, determined from the washin and washout rates of the radiodense, nonradioactive gas Xe, as measured in serial CT scans. We used the Xe-CT ventilation method, along with other quantitative CT measurements, to investigate the distribution of regional lung ventilation and air content in healthy, anesthetized, mechanically ventilated dogs in the prone and supine postures. Vertical gradients in regional ventilation and air content were measured in five mongrel dogs in both prone and supine postures at four axial lung locations. In the supine position, ventilation increased with dependent location, with a mean slope of 7.3%/cm lung height, whereas no ventilation gradients were found at any location in the prone position. These results agree quantitatively with other published studies. In addition, six different animals were studied (3 supine, 3 prone) to examine the longitudinal distribution of ventilation and air content. The prone lungs were more uniformly inflated compared with the supine, which were less well expanded at the base than apex. Ventilation index, a measure of regional ventilation relative to whole lung ventilation, increased steeply from apex to base in the supine animals, whereas it was again more uniform in the prone condition. We conclude that the Xe-CT method provides a reasonable, quantitative measurement of regional ventilation and promises to be a valuable tool for the noninvasive determination of regional lung function.

Animals↗

PubMed2001

Dynamic assessment of paranasal sinus ventilation using xenon-enhanced computed tomography.

Disease of the paranasal sinuses is a common and costly condition. Evaluation of the efficacy of either medical or surgical methods of treatment is limited by the lack of quantitative methods to characterize sinus ventilation, which may be an important determinant of the baseline physiological state of the sinuses. Xenon-enhanced computed tomography (Xe-CT) measurement of sinus ventilation provides a noninvasive method of quantifying maxillary sinus ventilation using the nonradioactive, radiodense gas Xe as a tracer. Study subjects breathed a mixture of Xe gas and oxygen through a close-fitting nasal mask during serial CT imaging of a single radiographic plane through the maxillary sinuses--a generally well-tolerated protocol. Analysis of the sinus density-time curves allowed calculation of first-order exponential time constants from which specific ventilation rates could be determined for individual sinuses. Previously developed data analysis techniques were used to assess the statistical significance of the data and determine confidence intervals, allowing examination of the effects of noise in the data, and to demonstrate areas for further study protocol refinement. We conclude that Xe-CT measurement of sinus ventilation is a potentially valuable noninvasive technique for the diagnostic imaging of the human maxillary sinus.

Humans↗

PubMed2000

Xenon-enhanced computed tomography quantifies normal maxillary sinus ventilation.

OBJECTIVE: The purpose of this study was to determine the applicability, safety, and normal parameters of a xenon-enhanced CT technique to quantify maxillary sinus ventilation. PATIENTS AND METHODS: Nine healthy subjects inhaled a xenon-oxygen-air mixture through their noses while repeated CT scans were performed through the same section of their sinuses. Images were obtained every 1 to 3 minutes and analyzed to measure the density of the gas in the maxillary sinus as a function of time. RESULTS: Individual nasal cavity time constants ranged from 0.5 to 18 minutes. Studies performed after decongestion showed poorer sinus ventilation. CONCLUSIONS: The xenon-CT washin/washout technique is safe, effective, and gives representative data.

Adult↗

PubMed1998

Parameter estimation and confidence intervals for Xe-CT ventilation studies: a Monte Carlo approach.

Xenon-enhanced computed tomography (Xe-CT) is a technique for the noninvasive measurement of regional pulmonary ventilation from the washin and/or washout time constants of radiodense stable xenon gas, determined from serial computed tomography scans. Although the measurement itself is straightforward, there is a need for methods for the estimation of variability and confidence intervals so that the statistical significance of the information obtained may be evaluated, particularly since obtaining repeated measurements is often not practical. We present a Monte Carlo (MC) approach to determine the 95% confidence interval (CI) for any given measurement. This MC method was characterized in terms of its unbiasedness and coverage of the CI. In addition, 10 identical Xe-CT ventilation runs were performed in an anesthetized dog, and the time constant was determined for several regions of varying size in each run. The 95% CI, estimated from these repeated measurements as the mean +/- 2 x SE, compared favorably with the CI obtained by the MC approach. Finally, a simulation was performed to compare the performance of three imaging protocols in estimating model parameters.

Animals↗

PubMedDate not supplied

Acute isovolemic hemodilution during major hepatic resection--an initial report: does it safely reduce the blood transfusion requirement?

Surgical resection remains the mainstay of treatment for patients with hepatic tumors, despite the associated morbidity including the need for blood transfusion. Acute isovolemic hemodilution (AIH) has been shown to decrease the transfusion requirement for cardiac, urologic, and orthopedic procedures. However, the reported experience with AIH during hepatic resections is limited. Seven patients underwent major hepatic resection from July 1992 to June 1994 with standard AIH. Their clinical parameters were compared with those of nine matched control patients during the same time period. AIH and control patients had similar preoperative laboratory values (hematocrit, bilirubin, and coagulation studies), extent of liver resection, and pathologic diagnoses. Mean tumor diameters were larger in the AIH group (9.3 cm vs. 5.8 cm). Most important, patients managed with AIH required homologous blood transfusions significantly less often than the control group (14% vs. 67%; P=0.05). Furthermore, if they did receive transfusions, AIH patients needed fewer units of red cells (0.1+/-0.1 units vs. 1.7+/-0.6 units). There was no morbidity associated with AIH. AIH can be safely performed in patients undergoing major hepatic resection for malignancy. AIH appears to reduce the number of patients requiring homologous blood transfusion as well as the number of units transfused per patient. This technique warrants further study in a larger prospective, randomized trial.

Blood Loss, Surgical↗