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Biomedical subjects

N Passuti

Publications and source records attributed to N Passuti.

At least 73 records · Page 4Linked to original sources
PubMed1991

Postoperative analgesia by intravenous clonidine.

Clonidine, an alpha 2 adrenoreceptor agonist, has nonopiate antinociceptive properties, which might be an alternative for postoperative analgesia free of opioid-induced side effects. To document the analgesic properties of intravenous clonidine during the postoperative period, 50 ASA physical status 1 patients, immediately after spinal fusion, were randomly assigned to two groups, blindly administered either clonidine (5 micrograms/kg infused the 1st h and then 0.3 microgram-1.kg-1.h-1 during 11 h) or a placebo. A visual analog scale graded from 0 (no pain) to 100 mm was used to assess pain before clonidine or placebo administration (T0), at the end of the loading dose (T1) and then every 2 h (T3, T5, T7, T9, and T11). Morphine (0.1 mg/kg) was administered intramuscularly after each pain measurement if the score was greater than 50 mm. No morphine was given at T0. Hemodynamics, blood gases and plasma clonidine concentrations were measured each time the pain score was measured. The pain score decreased from 42 +/- 5 to 26 +/- 3 mm (mean +/- standard error) in the clonidine group whereas it was unchanged in the placebo group despite a greater morphine requirement (dose for each patient: 3.8 +/- 1 vs. 10.8 +/- 1.2 mg). Clonidine delayed the onset of pain and the first request for morphine injection. Mean arterial pressure decreased to 74 +/- 2 mmHg in the clonidine group (-26 +/- 2 vs. -15 +/- 2% in the placebo group at T11) despite a significant increase in the cumulative fluid volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Clonidine↗
PubMed1991

[Vertebral involvement and fetal alcohol syndrome].

Vertebral abnormalities observed in 8 children with fetal alcohol syndrome are described and discussed. They include scoliosis (4 cases), neural tube defects (4 cases) and complex malformations of the cervical spine (2 cases). The latter probably constitute a different entity from that of the Klippel-Feil syndrome. It is probable that alcohol plays a direct role in the genesis of these abnormalities.

Female↗
PubMed1990

Macroporous calcium phosphate ceramic for long bone surgery in humans and dogs. Clinical and histological study.

Our previous studies reported the performance of Macroporous Biphasic Calcium Phosphate (MBCP) in spine fusion. In the present study, this material was used in block forms in selected patients with tumoral resection in long bone. Two cases were chosen with large benign bone tumors. Clinical and radiographic assessments, CT scans, and NMR were performed after 16 months, and in one case control biopsies were taken. In order to understand the kinetic process of biodegradation of the MBCP blocks and bone formation at the expense of the ceramics, an experimental study in surgically created bond defects in canine femoral cortices was made. The MBCP blocks recovered after implantation period from 2 to 18 weeks were analyzed using histological, stereological, ultrastructural, electron microprobe, and IR spectroscopy analyses. This study demonstrated the efficiency of MBCP blocks for filling pathological defects in human long bone. The biointegration process of the MBCP blocks was due to a partial dissolution of the ceramics crystals (b-TCP content) by multinucleated cells. Simultaneously, bone ingrowth at the expense of the ceramic is observed. The new bone formation inside the MBCP macropores and in the spaces between the blocks, involved the formation of a new cortical bone on the outer part, and a trabecularlike bone with bone marrow in the inner part of the implant. The biological resorption of the MBCP ceramic decreased after 1 month implantation in dog, due to the protective role of the newly formed lamellar bone on the surface and in the core of the ceramics.

Animals↗
PubMed1990

[Degenerative lumbar stenoses: value of the Cotrel-Dubousset instrumentation combined with lamino-arthrectomy. Apropos of 16 cases].

Sixteen patients suffering from degenerative lumbar stenosis with or without spondylolisthesis underwent surgery following medical treatment failure; symptoms consisted of intermittent claudication, radiculalgia, and lumbago. In all cases, treatment involved dural and nerve root release with extensive lamino-arthrectomy, followed by arthrodesis using the Cotrel and Dubousset Instrumentation with posterolateral arthrodesis in order to avoid postoperative spinal instability. One case met with failure, owing to peridural fibrosis caused by a previous operation, while fifteen good to excellent results were obtained as evaluated according to Stauffer and Coventry criteria.

Adult↗
PubMed1990

Effect of the macroporosity for osseous substitution of calcium phosphate ceramics.

The main property of calcium phosphate ceramics (CaP ceramics) is to be gradually substituted by newly formed bone or at least to be coalescent with the host bone. In cortical bone in dogs three kinds of porosity were tested (from 100 to 600 microns). The results demonstrate that the macropores up to 100 microns are efficient for the bone ingrowth, however during the first months of implantation larger macropore sizes are more suitable for bone ingrowth.

Animals↗
PubMed1989

[Plastic surgery of the anterior cruciate ligament: experimental study of intra-articular aramid fibers in dogs].

The authors explored the possibility of replacing an anterior cruciate ligament with an aramid fiber (Kevlar) implant. This study was performed in intra-articular site in 9 dogs and the average implantation period was 5 months. Studies were carried out by macroscopic, photon microscopy, and electron microscopy examination of the samples obtained at the time the animals were sacrificed. Clinical and radiographic studies of the knees were performed in order to assess functional consequences. Overall, the results showed a partial or complete rupture of 10 neoligaments out of the 17 studied ligaments; on the other hand, osseous anchorage and reintegration in the intra-articular zone appeared satisfactory. Kevlar fiber only partially meets the performance specifications for an artificial ligament intended to serve as an anterior cruciate ligament substitute. Some positive results have encouraged the authors to carry on further this experimental study.

Animals↗
PubMed1989

[Bone integration within calcium phosphate ceramic by creation of posterior inter-articular lumbar spine fusions in dogs].

Following earlier experiments in which several calcium phosphate ceramics were tested, the aim of this study was to evaluate bone integration within a macroporous biphasic calcium ceramic (M.B.C.P.) in comparison to autologous bone grafts, by producing posterior lumbar spine fusions in dogs. Five dogs were used. 40 posterior lumbar joints were exposed; 38 articular surfaces were removed, 27 M.B.C.P. and 5 autologous bone grafts were implanted; 6 joints were kept free of implant for control purposes. Fixation with a metal rod was performed using Luque's method. Tetracycline was used for a double marking of bone growth. Joints were removed at 4 weeks in 1 dog, 8 weeks in two and 13 weeks in the remaining 2 dogs. Demineralized and non demineralized sections were examined. After 1 month, sections with M.B.C.P. showed early signs of mineralization of the scar tissue between the biomaterial and one of the facets of the joint. Fluoroscopy revealed an absence of bone growth in the pores at the center of the ceramic implant. After 3 months, a number of M.B.C.P. blocks had become integrated into both sides of the joint; however some microfractures in the biomaterial with discontinuity between the mineralized areas was seen. Macroporous calcium phosphate ceramic leads to revascularization allowing bone reconstruction. Similarities in the kinetics and mechanisms of bone integration between the ceramic and autologous bone grafts are demonstrated.

Animals↗
PubMed1989

[Comparative study of bioactive calcium phosphate ceramics after implantation in spongy bone in dogs. Histologic, ultrastructural and electron probe microanalysis].

An experimental model of posterior spine arthrodesis in dogs was created using 3 types of calcium phosphate biomaterials already known for their applications as bone substitutes, namely: hydroxyapatite (HA), which is not readily resorbable; highly resorbable tricalcium phosphate (TCP); and a mixture of HA and TCP (BCP), the resorbability of which depends on the proportion of HA and TCP. The BCP implants had a macroporous structure, whilst the HA and TCP implants were used in dense form. The creation of macropores increases the surface exchange area, thus enabling the osseous colonization processes. By carefully removing the posterior articular facets it was possible to remove the articular surfaces and to fit into each appropriate location a block a few millimeters in diameter. The anatomopathological assessment was performed using histological methods, transmission electron microscopy, and energy dispersion microprobe analysis. Our results indicate that calcium phosphate ceramics may be used as bone substitutes for carrying out arthrodeses, provided (1) immediate immobilization using a spine containment technique is effected; (2) their chemical composition is sufficiently stable over time; (3) they are sufficiently bioactive so as to allow their colonization and replacement by bone.

Animals↗
PubMed1989

Hypotensive anesthesia with isoflurane and enflurane during total hip replacement: a comparative study of catecholamine and renin angiotensin responses.

Catecholamine and renin-angiotensin responses to enflurane- or isoflurane-hypotensive anesthesia were compared in a randomized study. Two groups of 10 patients undergoing total hip arthroplasty were premedicated with morphine hydrochloride (0.1 mg/kg). Anesthesia was induced with thiopental and the trachea intubated after pancuronium. Equal concentrations of each volatile agent (1.3 MAC) were administered until mean arterial blood pressure decreased to 50-60 mm Hg. Hemodynamic data and blood samples for measurements of plasma renin activity (PRA) and plasma epinephrine (E) and norepinephrine (NE) concentrations were collected 1) after induction and intubation but before the start of isoflurane or enflurane; 2) 15 min (T15) after the start of isoflurane or enflurane administration; and 3) 45 min (T45) after the start of isoflurane or enflurane administration. The desired level of hypotension was achieved at T15 with isoflurane and at T45 with both anesthetics. When hypotension was achieved, cardiac index and stroke index were significantly lower in the enflurane group while systemic vascular resistance index was lower in the isoflurane group. Increases in E and NE levels above baseline levels were significantly greater in the isoflurane group than in the enflurane group. Use of isoflurane to induce hypotension is associated with more rapid induction of hypotension, less depression of cardiac output, and better preservation of homeostatic responses than is use of enflurane.

Enflurane↗
PubMed1989

[Extensometry and primary anchorage of femur implants. Study of the upper metaphyseal intracortical support of the B.P.R cement-less implant].

This study uses extensometry to compare the distribution of strain on a fresh femur before and after implantation of various titanium prostheses: one is a cementless implant with metaphyseal endosteal support; the second is a cemented prosthesis with and without calcar collar contact; the last is a titanium implant with fixation by screens. The precision of the measurements have been improved particularly in the proximal metaphyseal area using bidirectional gauges. The system of loading permits comparison of the different implants and the results obtained with the B.P.R. prosthesis compared with the cemented implant without calcar contact are very close. The effect of the collar appears very limited despite the optimal conditions of the in vivo implantation that improve the calcar-collar contact. The screw implant increases the stress shielding of the proximal area of the femur. The different steps of the experiment illustrate the strain distribution in relation to the implantation of the devices and the contact bone prosthesis. The significant endosteal fixation of the B.P.R. prosthesis in the proximal metaphyseal area allows a better primary anchorage which increases distribution of the stress and therefore results in better secondary fixation by bony ingrowth.

Biomechanical Phenomena↗
PubMed1989

Macroporous calcium phosphate ceramic performance in human spine fusion.

With a background of experimental studies on macroporous biphasic calcium phosphate (MBCP) in canine spine fusion, MBCP was investigated in 11- to 18-year-old patients with scoliosis treated by spinal fusion. Twelve cases were chosen for whom enough bone graft was difficult to obtain (severe neurologic scoliosis and osteogenesis imperfecta). MBCP blocks were used in combination with a specific strong fixation (Cotrel-Dubousset instrumentation). Clinical and roentgenogram assessments were performed up to 24 months. In two cases, biopsies were obtained. Histologic, ultrastructural, and microanalysis studies demonstrated the effectiveness of MBCP implants combined with a strong stabilization as bone graft substitutes for spine fusion. Clinical and biologic assessments were normal, and the histologic and ultrastructural evaluation demonstrated the bioactivity and the osteoconduction of this material. Partial resorbability of the MBCP blocks involved lamellar bone formation at the expense of the ceramic.

Adolescent↗
PubMed1988

Additive effects of dihydralazine during enflurane or isoflurane hypotensive anaesthesia for spinal fusion.

Sixteen patients (13-38 yr) undergoing spinal fusion for scoliosis under controlled hypotension were studied to determine the haemodynamic and neuroendocrine responses to IV dihydralazine (1.0 mg.kg-1) followed by 0.5 and 1 MAC of enflurane or isoflurane. Twenty minutes after dihydralazine administration mean arterial pressure (-20 per cent) and systemic vascular resistance (-50 per cent) decreased, and cardiac index (+57 per cent), heart rate (+37 per cent) and intrapulmonary shunt increased. Plasma renin activity and aldosterone and norepinephrine levels increased. Further decreases in mean arterial pressure and in systemic vascular resistance were observed when 0.5 MAC enflurane or isoflurane were added. With 1 MAC anaesthetic levels a further decrease in mean arterial pressure was observed in both groups, but pressure fell to a lower level with isoflurane than with enflurane (p less than 0.01). The reduction of arterial blood pressure to a level of 50-60 mmHg for three to four hours was easy to control and was free of complications. The preliminary IV administration of dihydralazine allowed a reduced volatile agent concentration which attenuated undesirable haemodynamic effects, in spite of renin and norepinephrine release, and permitted a rapid intraoperative awakening.

Adolescent↗
PubMed1988

[Fatal cardiac complications in a child operated on for severe scoliosis with a Coffin-Lowry syndrome. Apropos of a case].

The Coffin-Lowry is characterized by mental retardation, characteristic facies and hands, and skeletal changes. Discovery of two others brothers presenting vertebral curvature and suffering from the same syndrome led to a familial investigation which allowed the making of an inventory of six members affected in this family. Only subjects with characteristic fingers were included because according to Lowry this anomaly is necessary to assert the Coffin-Lowry syndrome. The series is quite interesting because this is the greatest of Lowry with five cases. The authors emphasize the importance of a detailed preoperative cardiac exploration to search for cardiomyopathy the existence of which in Coffin-Lowry syndrome was never noted before.

Abnormalities, Multiple↗