RESUMEN
In six pigs with prefabricated transposition flaps and six pigs with prefabricated advancement flaps, both flap types (lined with an expander capsule) were used to reconstruct wedge excisions of the lower eyelid or defects in the cheek/oral mucosa. The capsules replaced the conjunctiva in eyelid defects and the oral mucosa in cheek defects. Histopathologic studies were performed at 5 to 7 days, 9 to 10 days, 2 weeks, 3 to 4 weeks, and 2 and 3 months after flap reconstructions. Healing was rapid and uneventful, leading to restoration of the conjunctiva/eyelid and oral mucosa between 9 days and 2 weeks. The healing of the eyelid conjunctiva was somewhat faster than of the oral mucosa. The expander capsule acted as a conjunctival/ mucosal substitute, providing a temporary physical shield, an infectious barrier, and a matrix for epithelial regeneration. All reconstructions were successful except one oral reconstruction with early flap necrosis. Flaps lined with an expander capsule could improve and facilitate clinical reconstructions in the eyelid and oral cavity.
Asunto(s)
Párpados/cirugía , Mucosa Bucal/cirugía , Colgajos Quirúrgicos/patología , Dispositivos de Expansión Tisular , Animales , Conjuntiva/patología , Párpados/patología , Mucosa Bucal/patología , Porcinos , Cicatrización de Heridas/fisiologíaRESUMEN
Severe developmental breast deformities cause deep psychological problems in young women and disturb their social relations. New techniques and traditional breast implants, or the combined expander implants permitting gradual augmentation of a small breast, yield results which afford such young women an opportunity of living normal lives. Of 326 applicants for corrective breast surgery, 26 were found to have developmental breast deformities: thoracic deformity (n = 4), scoliosis (n = 1), Amazon syndrome (unilateral amastia or hypoplasia; n = 5), other breast asymmetries (n = 5), or tubular/tuberous deformity, unilaterally (n = 5) or bilaterally (n = 7) (one patient had both tubular deformity and Amazon syndrome). In the 14-20-year-old age group (n = 11), breast correction took the form of conventional implants in two cases, and combined expander implants in six cases, the corresponding figures in the 21-62-year-old age group (n = 15) being eight and five cases, respectively. Only implants were used in 10 cases, and different combinations of nipple/areolar mammoplasty, mastopexy and reduction in 16 cases. Volume symmetry was good in 24 cases and acceptable in two, and breast shape good in 19 cases, acceptable in five cases, but still asymmetrical in the remaining two cases as the patients declined contralateral ptotic breast correction. Nipple/areolar sensitivity was normal and scars good or acceptable in all cases. One patient developed capsular contraction, and another a mild form of striae. Duration of follow-up is over two years in 22 cases.
Asunto(s)
Implantación de Mama/métodos , Implantes de Mama , Mama/anomalías , Mamoplastia/métodos , Elastómeros de Silicona , Geles de Silicona , Adolescente , Adulto , Mama/cirugía , Implantación de Mama/efectos adversos , Implantes de Mama/efectos adversos , Femenino , Estudios de Seguimiento , Humanos , Mamoplastia/efectos adversos , Pezones/anomalías , Pezones/cirugía , Elastómeros de Silicona/efectos adversos , Geles de Silicona/efectos adversos , Técnicas de SuturaRESUMEN
Tissue expansion of adjacent intact skin and subcutaneous tissue has in five legs provided high-quality soft-tissue coverage of the distal end in legs amputated at different levels without further shortening of the bone. The sensitivity of slowly expanded flaps is temporarily affected but eventually seems to return to normal. Expanded flaps have endured both sitting and the use of prostheses for 4 to 5 years. In one case the technique made it possible to save the knee joint. Besides being a functional reconstruction, the appearance of the reconstructed parts much improved. A technique of overexpansion and double flap coverage of the bone utilizing deepithelialization is described.
Asunto(s)
Muñones de Amputación/cirugía , Amputación Traumática/cirugía , Traumatismos de la Pierna/cirugía , Expansión de Tejido , Adolescente , Adulto , Estudios de Seguimiento , Humanos , Masculino , Sensación , Colgajos Quirúrgicos , Factores de Tiempo , Dispositivos de Expansión TisularRESUMEN
The effect of the fibrinolysis inhibitor tranexamic acid on early thrombus formation following microvascular trauma was investigated in the central arteries of ears in 86 rabbits (in all 172 vessels), divided into four separate blind randomised studies. In the first part a common end-to-end anastomosis was done and in the last three studies a severe trauma-arteriotomy/intimectomy was performed. Parameters studied were vessel bleeding times, patency rates, weights of intraluminal thrombotic material, haematocrit and plasma fibrinolytic activity. In the first study consisting of 14 control animals and 18 animals treated with 14 mg/kg bw of tranexamic acid, end-to-end anastomosis was performed on the central artery of one ear and on the central vein of the other ear. In the second, third, and fourth studies consisting of 18, 20, and 16 control vessels and the same number of corresponding vessels in treated animals a 7-mm longitudinal arteriotomy followed by a deep 5-mm-long intimectomy was performed. The second and third treated groups were given 14 mg/kg bw of tranexamic acid 5 min and 1 h, respectively, before reflow and the fourth group 28 mg/kg bw 5 min before reflow. The difference between the second and third studies was the addition, to mimic clinical situations, of 8.5 ml saline/kg bw 2 h before reflow in the third study. In conclusion, treatment with a single clinical dose, 14 mg/kg of tranexamic acid, did not influence vessel bleeding times or thrombus formation in the anastomotic or severe trauma models and seems safe to use. Not even a double clinical dose, 28 mg/kg, influenced thrombus formation in a statistically significant way.
Asunto(s)
Antifibrinolíticos/uso terapéutico , Arterias/lesiones , Terapia Trombolítica , Ácido Tranexámico/uso terapéutico , Anastomosis Quirúrgica , Animales , Oído/irrigación sanguínea , Masculino , Conejos , Trombosis/etiología , Trombosis/prevención & control , Factores de TiempoRESUMEN
Cardiotoxicity is an unexplained toxic manifestation of 5-fluorouracil (5-FU). Its possible mechanism could be a direct cytotoxic effect on the vascular endothelium. We have tested this hypothesis in an experimental study in rabbits, using scanning and transmission electron microscopic evaluation of endothelium in small arteries (the central artery of the ear). The perfusion fixation method at physiological pressure and temperature was used. Both local and systemic effects of 5-FU on endothelium were studied 1, 3, 7, 14 and 30 days after in vivo treatment with 5-FU. Fifteen rabbits were used and five additional animals served as controls. The following parameters were evaluated: vessel wall and endothelial cell contraction, cell oedema, cytolysis, occurrence of denuded areas, platelet adhesion/aggregation and fibrin formation. For the description of each parameter, a scale of negative points (0.0-3.0) was used. We found severe cell damage with accompanying thrombus formation. The findings support the hypothesis that the thrombogenic effect of 5-FU, secondary to its direct cytotoxic effect on endothelium, is the pathophysiological mechanism behind 5-FU cardiotoxicity.
Asunto(s)
Antimetabolitos Antineoplásicos/toxicidad , Arterias/efectos de los fármacos , Endotelio Vascular/efectos de los fármacos , Fluorouracilo/toxicidad , Animales , Arterias/ultraestructura , Endotelio Vascular/ultraestructura , Masculino , Microscopía Electrónica de Rastreo , ConejosRESUMEN
The study was composed of two parts, arterial and venous; the 24 rabbits in each arm were divided into three equal groups and treated with either saline (control) or 1 mg/kg body weight (bw) of a new recombinant hirudin HBW 023 given as a single dose or standard heparin 1 mg/kg bw followed by quarter doses of heparin every half hour. Both arms included a control group given equal volumes of saline. The study continued for 2 hours. The following parameters were evaluated: bleeding times from arteriotomy/venotomy, patency rates, and the weights of thrombotic materials. Plasma samples were taken for evaluation of anti-factor lla (anti-Flla), anti-factor Xa (anti-Fxa), and activated partial thromboplastin time (APTT). The bleeding times were significantly prolonged but were still within clinically acceptable levels, following both HBW 023 and heparin treatment. Patency rates were significantly improved in both the arterial and venous arms following HBW 023 and heparin treatment. A corresponding reduction in thrombotic materials was simultaneously registered in the arterial and venous arms following HBW 023 and heparin treatment. Hirudin (HBW 023) significantly improved the reduction compared with the heparin group in the venous study. Heparin treatment caused expected high levels of anti-FXa and prolonged APTT, but hirudin, being at least as effective in antithrombotic potency, changed the pre-treatment levels only slightly. Anti-Flla levels were immediately increased by both heparin and hirudin (the highest levels) but reached low levels after 2 hours of single-dose hirudin treatment, despite a simultaneously excellent antithrombotic effect. We conclude that the new recombinant hirudin HBW 023, like standard heparin, is a highly efficient antithrombotic agent in both small arteries and veins following severe vessel wall trauma. The bleeding times were simultaneously prolonged significantly (still within acceptable limits) following both heparin and HBW 023 treatment in the arterial arm but were only prolonged following heparin treatment in the venous arm. The advantage of r-hirudin HBW 023 was furthermore the single dose administration.
Asunto(s)
Anticoagulantes/uso terapéutico , Antitrombinas/uso terapéutico , Heparina/uso terapéutico , Terapia con Hirudina , Animales , Anticoagulantes/administración & dosificación , Antitrombinas/administración & dosificación , Arterias/efectos de los fármacos , Arterias/lesiones , Arterias/ultraestructura , Pruebas de Coagulación Sanguínea , Esquema de Medicación , Factor Xa/análisis , Heparina/administración & dosificación , Hirudinas/administración & dosificación , Masculino , Tiempo de Tromboplastina Parcial , Protrombina/análisis , Conejos , Distribución Aleatoria , Proteínas Recombinantes/administración & dosificación , Proteínas Recombinantes/uso terapéutico , Método Simple Ciego , Cloruro de Sodio , Trombosis/prevención & control , Grado de Desobstrucción Vascular , Venas/efectos de los fármacos , Venas/lesiones , Venas/ultraestructuraRESUMEN
5-Fluorouracil (5-FU) is a widely used antineoplastic agent. 5-FU induced cardiotoxicity is a still relatively unknown side-effect of this drug. This phenomenon could be due to a direct cytotoxic effect on the endothelial cells. We tested this hypothesis in an experimental study in rabbits, by scanning or transmission electron microscopic evaluation of endothelium in small arteries (the central artery of the ear) after in vivo treatment with 5-FU. Both local and systemic effects of 5-FU on endothelium were studied 15, 30, 60 and 120 minutes after intra-arterial or intraperitoneal treatment. Perfusion fixation at physiological pressure and temperature was used in order to minimize damage to the endothelium during the preparation procedure. Eighteen rabbits weighing 2.5-3.0 kg were used, and 6 animals served as controls. The following parameters were evaluated: vessel wall and endothelial cell contraction, cell edema, cytolysis, occurrence of denuded areas, platelet adhesion/aggregation and fibrin formation. For the description of each parameter a scale of negative points was used. Irreversible cell damage was observed in 5-FU treated animals: disruption of the endothelial sheet and patchy exposure of the subendothelium, sometimes as a focus for thrombus formation. Our findings support the hypothesis that the thrombogenic effect of 5-FU secondary to its direct cytotoxic effect on endothelium might be one of the pathophysiological mechanisms behind 5-FU induced cardiotoxicity.
Asunto(s)
Antimetabolitos Antineoplásicos/toxicidad , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/ultraestructura , Fluorouracilo/toxicidad , Microscopía Electrónica de Rastreo , Microscopía Electrónica , Animales , Arterias/efectos de los fármacos , Arterias/lesiones , Arterias/ultraestructura , Endotelio Vascular/lesiones , Corazón/efectos de los fármacos , Masculino , Conejos , Factores de TiempoAsunto(s)
Amputación Quirúrgica/métodos , Amputación Traumática/cirugía , Diferencia de Longitud de las Piernas/prevención & control , Pierna/cirugía , Dispositivos de Expansión Tisular , Adolescente , Adulto , Estudios de Seguimiento , Humanos , Masculino , Ajuste de Prótesis , Reoperación , Cicatrización de HeridasRESUMEN
Patency rats and accumulation of 32P-labelled platelets were studied in the central ear arteries of rabbits (which were not treated with antithrombotic agents) after three types of vascular injury: End to end anastomosis, arteriotomy and superficial injury to the vessel wall to expose the lamina elastica interna/juxtaluminal parts of the tunica media, arteriotomy and deep injury to the vessel wall to expose the deeper layers of the tunica media. The superficial and deep vessel injuries were 5 mm long. Patency rates were 100% after end to end anastomosis and superficial injury, and 48% after deep injury. In a separate group of vessels with deep injuries the time course of formation of occlusive thrombi was investigated: occlusion was already present 15 minutes after reperfusion in all but one of seven occluded vessels. Platelet accumulation ratios were significantly higher after deep injury than after end to end anastomosis or superficial injury. In deeply injured patent vessels, platelet accumulation reached a maximum after about 30 minutes, which was later followed by a gradual decrease. Platelet accumulation patterns indicating sustained thrombogenicity throughout the measurement interval (embolization/reaccumulation patterns or late increases in accumulation) were encountered in only three of 22 deeply injured vessels. We conclude that: to cause formation of occlusive thrombus in otherwise healthy arteries and animals, a deep injury to the tunica media is necessary, and following reperfusion after repair of damaged vessels the time course of the thrombotic challenge is short.
Asunto(s)
Arterias/patología , Microcirugia , Agregación Plaquetaria , Trombosis/fisiopatología , Procedimientos Quirúrgicos Vasculares , Anastomosis Quirúrgica , Animales , Femenino , Masculino , Conejos , Grado de Desobstrucción VascularRESUMEN
A clinical dose of dextran 70 had significant antithrombotic effects in small, severely traumatized veins, and the effect was enhanced by the addition of low-molecular-weight heparin. These effects were achieved without bleeding problems in this model.
Asunto(s)
Dextranos/uso terapéutico , Heparina de Bajo-Peso-Molecular/uso terapéutico , Trombosis/tratamiento farmacológico , Grado de Desobstrucción Vascular/efectos de los fármacos , Animales , Quimioterapia Combinada , Factor Xa/metabolismo , Hematócrito , Masculino , Tiempo de Tromboplastina Parcial , Conejos , Terapia Trombolítica , Trombosis/sangre , Venas/efectos de los fármacos , Venas/fisiopatologíaRESUMEN
A severe microarterial trauma (arteriotomy/intimectomy) was introduced to the central arteries of rabbit ears. Twenty-one patent vessels, 3 at each interval of 2 hours, 1, 3, 7, 14, 30, and 90 days after reperfusion were taken for light and scanning electron microscopy studies. These vessels remained patent at all time intervals. A physiological "in vivo" perfusion technique with fixation fluid of normal temperature (37 degrees C), pressure (120 mm Hg) and osmolarity (300 mOsm) was used to ensure fixed relaxed vessels. The endothelial, internal elastic, and part of the medial layers of vessel walls were removed following intimectomy. The inner surface of the intimectomy region was irregular and partly covered with thrombotic materials between 2 hours and 3 days postreperfusion. Endothelialization of the traumatized region was first observed at 3 days and was completed between 7 and 14 days. Intimal hyperplasia developed during this period and had not diminished in thickness by 30 or 90 days. The trauma and healing process of the arteriotomy/intimectomy are similar to the healing of vascular anastomoses and virtually identical to the clinical trauma of vessel avulsion, but neointima formation is more pronounced and engages vessel walls far outside the intimectomy site.
Asunto(s)
Oído Externo/irrigación sanguínea , Animales , Arterias/lesiones , Arterias/patología , Tejido Elástico/lesiones , Tejido Elástico/patología , Endotelio Vascular/lesiones , Endotelio Vascular/patología , Hiperplasia , Masculino , Microcirculación , Microscopía Electrónica de Rastreo , Músculo Liso Vascular/lesiones , Músculo Liso Vascular/patología , Conejos , Trombosis/patología , Factores de Tiempo , Túnica Íntima/lesiones , Túnica Íntima/patología , Túnica Media/lesiones , Túnica Media/patología , Grado de Desobstrucción Vascular , Cicatrización de HeridasRESUMEN
Twenty-seven rabbits divided into 4 groups (2 control groups) received saline, standard heparin (400 IU both as anti-F Xa and activated partial thromboplastin time per kg of body weight), or low molecular weight heparin (lmwh) (Fragmin 560 IU as anti-F Xa and 140 IU as APTT units per kg of body weight). The figures represent the total dose given over 3 hours. The central arteries of the rabbits' ears were prepared and positioned in clamps. Platelets labeled with 32P were injected. Arteriotomy/intimectomy was performed. After reestablishment of blood flow, arteriotomy bleeding times, platelet accumulation, patency, and weight of thrombotic materials were measured. The bleeding time in the Heparin Group was significantly prolonged compared with its control group. But the bleeding times between the LMWH Group and the control group were not significantly different. The patency rates were increased in both the Heparin Group (100%, p < 0.01) and the LMWH Group (73%, p = 0.078) compared with respective control groups (43-50%). The mean weights of thrombotic material in each artery were significantly lower in the Heparin Group and in the LMWH Group than in their control groups. The mean values of radioactivity in all groups increased up to 15 minutes after the vessels were reperfused. There were no statistical differences between the treated groups and control groups. It was concluded that standard heparin is a very powerful inhibitor of thrombosis during the most crucial hours after reperfusion of severely traumatized small arteries, without significant effects on primary platelet adhesion/aggregation.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Plaquetas/efectos de los fármacos , Heparina de Bajo-Peso-Molecular/farmacología , Heparina/farmacología , Trombosis/prevención & control , Animales , Arterias/efectos de los fármacos , Arterias/lesiones , Masculino , Conejos , Distribución Aleatoria , Grado de Desobstrucción Vascular/efectos de los fármacosRESUMEN
In two separate blind, randomized studies, 48 rabbits were divided into five groups. Three treated groups received dextran 70 (0.51 g/kg) as a single injection, dextran 70 combined with low molecular-weight heparin (LMWH) (560 IU/kg as anti-FXa and 140 IU/kg as APTT in 3 hr), and dextran 70 plus tranexamic acid (14 mg/kg) following severe arterial trauma (arteriotomy/intimectomy). Two control groups received the same amount of saline. The bleeding times from the arteriotomy were recorded, and patency rates and the weight of thrombotic materials were registered 2 hr after reperfusion of the trauma region. The bleeding times in three treated groups, all including dextran, were significantly prolonged compared to the control groups (P < 0.05 or 0.01). The patency rates of treated groups, which were 100% (18/18 vessels patent) in the dextran-treated group, 90% (18/20 vessels patent) in the dextran+LMWH group and 95% 19/20 vessels patent) in dextran+tranexamic acid group, were significantly higher than those of their control groups (55-67% patent vessels) (p < 0.05 or 0.01). The mean weights of thrombotic materials were significantly reduced in the treated groups compared to the corresponding control groups (p < 0.01). In conclusion, dextran 70 in an ordinary dose exerted such a profound antithrombotic effect (100% patency) in small traumatized arteries that the addition of a high dose of LMWH could not further improve patency rates or decrease thrombotic materials but did not prolong vessel bleeding times compared to the single dextran treatment.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Dextranos/farmacología , Fibrinólisis/efectos de los fármacos , Heparina de Bajo-Peso-Molecular/farmacología , Trombosis/sangre , Ácido Tranexámico/farmacología , Animales , Arterias/cirugía , Tiempo de Sangría , Relación Dosis-Respuesta a Droga , Oído Externo/irrigación sanguínea , Fibrinólisis/fisiología , Masculino , Conejos , Grado de Desobstrucción Vascular/efectos de los fármacosRESUMEN
In a blind, randomized study, two groups, each of seven rabbits, were treated with either a very low dose of human melanoma cell line-derived tissue-type plasminogen activator (t-PA) or isotonic saline. t-PA (0.067 mg/kg of body weight) was administered intraaortically, 20 percent being given as a 30-second "bolus" infusion just prior to the reperfusion of intimectomized central ear arteries and the rest as a continuous infusion during the next 2 hours. Arteriotomic bleeding times, accumulations of 32P-labeled platelets, patency, and sizes of thrombus deposits 2 hours after reperfusion were recorded. To confirm the presence of tissue plasminogen activator in plasma, fibrin-plate lysis assays of arterial plasma were performed immediately before and 1/2 hour and 2 hours after starting drug infusion. Arteriotomic bleeding times were similar in both groups. Transient "oozing" from wound edges occurred in 40 percent of rabbits treated with tissue plasminogen activator. Patency was significantly increased and thrombus deposits were smaller in the tissue plasminogen activator group. Plasma from animals treated with tissue plasminogen activator caused massive lysis of fibrin plates, whereas plasma from control animals caused little or no lysis. Platelet accumulations were very similar in both groups, indicating that occlusive thrombi mainly consisted of other elements than platelets (e.g., fibrin and red cells). Scanning electron microscopy showed normally adhering and aggregating platelets in both groups. This study shows that mild fibrinolytic stimulation with tissue plasminogen activator significantly improves patency in severely traumatized small-caliber arteries and indicates that such treatment may be one approach to prevent thrombosis at microvascular anastomotic sites.
Asunto(s)
Trombosis/prevención & control , Activador de Tejido Plasminógeno/administración & dosificación , Animales , Tiempo de Sangría , Plaquetas/efectos de los fármacos , Plaquetas/fisiología , Oído Externo/irrigación sanguínea , Fibrinólisis/efectos de los fármacos , Microcirculación/cirugía , Microcirculación/ultraestructura , Microcirugia , Conejos , Grado de Desobstrucción Vascular/efectos de los fármacosRESUMEN
Administration of low-molecular-weight heparin (LMWH) and standard heparin was studied by evaluating vessel bleeding, patency, and thrombotic material following severe vascular trauma. Arteriotomy and intimectomy or venotomy and intimectomy were performed on small rabbit arteries or veins in two separate blinded studies. All vessels were closed using a continuous microvascular suture. Patency and weight of thrombotic materials were evaluated 2 hr after reperfusion. In the arterial study, two groups of 23-24 arteries were treated with saline or LMWH systemically. Bleeding times were 89 +/- 15 sec in the control group and 103 +/- 27 sec in the LMWH group; there was no significant difference between the groups. Patency was significantly increased in the LMWH group (79%) compared to the control group (52%). The weight of thrombotic material in the LMWH group (1.39 +/- 0.20 mg per artery) was significantly different compared to the control group (2.19 +/- 0.22 mg per artery). In the venous study, 65 veins were divided into three groups (21-23 vessels/group) and treated with systemic saline, heparin, or LMWH. Bleeding times in the conventional heparin group (37 +/- 7 sec), the control group (23 +/- 3 sec), and LMWH group (22 +/- 4 sec) were not significantly different. The patency rates were significantly increased in the heparin (42%) and LMWH (39%) groups compared to the control group (0%). The weight of thrombotic material in each vein was significantly less in the LMWH (1.07 +/- 0.24 mg) and heparin (1.78 +/- 0.52 mg) groups than in the control group (3.78 +/- 0.29 mg).(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Oído Externo/irrigación sanguínea , Fibrinolíticos/uso terapéutico , Heparina de Bajo-Peso-Molecular/uso terapéutico , Animales , Arterias/patología , Arterias/cirugía , Coagulación Sanguínea/efectos de los fármacos , Arteria Femoral/patología , Arteria Femoral/cirugía , Vena Femoral/patología , Vena Femoral/cirugía , Masculino , Microcirugia , Conejos , Flujo Sanguíneo Regional , Trombosis/patología , Factores de Tiempo , Grado de Desobstrucción Vascular/efectos de los fármacos , Venas/patología , Venas/cirugíaAsunto(s)
Cirugía Plástica/métodos , Expansión de Tejido/métodos , Adolescente , Adulto , Brazo/cirugía , Mama/cirugía , Niño , Preescolar , Procedimientos Quirúrgicos Dermatologicos , Femenino , Humanos , Masculino , Nevo/cirugía , Cuero Cabelludo/cirugía , Dispositivos de Expansión Tisular , Heridas y Lesiones/cirugíaRESUMEN
About 10 h after administering acetylsalicylic acid (ASA) orally in doses of 4 mg and 20 micrograms/kg b.w., the central arteries of rabbit ears were subjected to severe vascular trauma (arteriotomy/intimectomy). Bleeding times from the trauma regions at reperfusion were measured and the activities from accumulating 32P-labelled homologous platelets recorded until 2 h after reperfusion when patencies were determined. In other studies, the effects of ASA on ex vivo platelet aggregation (aggregometry), thromboxane production, euglobulin clot lysis time and bleeding time following arterial puncture were investigated. Relative to controls, the following parameters were changed: patency was increased, as were the bleeding times following arterial puncture and thromboxane production was reduced. The median values of platelet accumulation were lower, but the changes were not statistically significant. Aggregometry showed decreased rates of platelet aggregability following treatment with ASA 4 mg/kg.