A rigid barrier between the heart and sternum protects the heart and lungs against rupture during negative pressure wound therapy

<p>Abstract</p> <p>Objectives</p> <p>Right ventricular heart rupture is a devastating complication associated with negative pressure wound therapy (NPWT) in cardiac surgery. The use of a rigid barrier has been suggested to offer protection against this lethal complication, by preventing the heart from being drawn up and damaged by the sharp edges of the sternum. The aim of the present study was to investigate whether a rigid barrier protects the heart and lungs against injury during NPWT.</p> <p>Methods</p> <p>Sixteen pigs underwent median sternotomy followed by NPWT at -120 mmHg for 24 hours, in the absence (eight pigs) or presence (eight pigs) of a rigid plastic disc between the heart and the sternal edges. The macroscopic appearance of the heart and lungs was inspected after 12 and 24 hours of NPWT.</p> <p>Results</p> <p>After 24 hours of NPWT at -120 mmHg the area of epicardial petechial bleeding was 11.90 ± 1.10 cm²when no protective disc was used, and 1.15 ± 0.19 cm²when using the disc (p < 0.001). Heart rupture was observed in three of the eight animals treated with NPWT without the disc. Lung rupture was observed in two of the animals, and lung contusion and emphysema were seen in all animals treated with NPWT without the rigid disc. No injury to the heart or lungs was observed in the group of animals treated with NPWT using the rigid disc.</p> <p>Conclusion</p> <p>Inserting a rigid barrier between the heart and the sternum edges offers protection against heart rupture and lung injury during NPWT.</p

Effects on heart pumping function when using foam and gauze for negative pressure wound therapy of sternotomy wounds

<p>Abstract</p> <p>Background</p> <p>Negative pressure wound therapy (NPWT) has remarkable effects on the healing of poststernotomy mediastinitis. Foam is presently the material of choice for NPWT in this indication. There is now increasing interest in using gauze, as this has proven successful in the treatment of peripheral wounds. It is important to determine the effects of NPWT using gauze on heart pumping function before it can be used for deep sternotomy wounds. The aim was to examine the effects of NPWT when using gauze and foam on the heart pumping function during the treatment of a sternotomy wound.</p> <p>Methods</p> <p>Eight pigs underwent median sternotomy followed by NPWT at -40, -70, -120 and -160 mmHg, using foam or gauze. The heart frequency, cardiac output, mean systemic arterial pressure, mean pulmonary artery pressure, central venous pressure and left atrial pressure were recorded.</p> <p>Results</p> <p>Cardiac output was not affected by NPWT using gauze or foam. Heart frequency decreased during NPWT when using foam, but not gauze. Treatment with foam also lowered the central venous pressure and the left atrial pressure, while gauze had no such effects. Mean systemic arterial pressure, mean pulmonary artery pressure and systemic vascular resistance were not affected by NPWT. Similar haemodynamic effects were observed at all levels of negative pressure studied.</p> <p>Conclusions</p> <p>NPWT using foam results in decreased heart frequency and lower right and left atrial filling pressures. The use of gauze in NPWT did not affect the haemodynamic parameters studied. Gauze may thus provide an alternative to foam for NPWT of sternotomy wounds.</p

Addition of vardenafil into storage solution protects the endothelium in a hypoxia-reoxygenation model

OBJECTIVE: Based upon the well known protective effect of intracellular cyclic guanosine monophosphate (cGMP) accumulation, we tested the hypothesis that storage solution enriched with optimal concentration of the phosphodiestherase-5 inhibitor vardenafil could provide better protection of vascular grafts against reperfusion injury after long-term cold ischaemic storage. METHODS: Isolated thoracic aorta obtained from rats underwent 24-h cold ischaemic preservation in physiological saline or vardenafil (10(-11) M)-supplemented saline solution. Reperfusion injury was simulated by hypochlorite (200 muM) exposure for 30 minutes. Endothelium-dependent vasorelaxation was assessed, and histopathological and molecular-biological examination of the aortic tissue were performed. RESULTS: Compared with the control group, the saline group showed significantly attenuated endothelium-dependent maximal relaxation (Rmax) to acetylcholine after hypoxia-reoxygenation, which was significantly improved by vardenafil supplementation (Rmax control: 98 +/- 1%; saline: 48 +/- 6%; vardenafil: 75 +/- 4%; p < .05). Vardenafil treatment significantly reduced DNA strand breaks (control: 10.6 +/- 6.2%; saline: 72.5 +/- 4.0%; vardenafil: 14.2 +/- 5.2%; p < .05) and increased cGMP score in the aortic wall (control: 8.2 +/- 0.6; saline: 4.5 +/- 0.3; vardenafil: 6.7 +/- 0.6; p < .05). CONCLUSIONS: Our results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction induced by cold storage warm reperfusion, which can be effectively reversed by pharmacological phosphodiesterase-5 inhibition

Wound contraction and macro-deformation during negative pressure therapy of sternotomy wounds

<p>Abstract</p> <p>Background</p> <p>Negative pressure wound therapy (NPWT) is believed to initiate granulation tissue formation via macro-deformation of the wound edge. However, only few studies have been performed to evaluate this hypothesis. The present study was performed to investigate the effects of NPWT on wound contraction and wound edge tissue deformation.</p> <p>Methods</p> <p>Six pigs underwent median sternotomy followed by magnetic resonance imaging in the transverse plane through the thorax and sternotomy wound during NPWT at 0, -75, -125 and -175 mmHg. The lateral width of the wound and anterior-posterior thickness of the wound edge was measured in the images.</p> <p>Results</p> <p>The sternotomy wound decreased in size following NPWT. The lateral width of the wound, at the level of the sternum bone, decreased from 39 ± 7 mm to 30 ± 6 mm at -125 mmHg (p = 0.0027). The greatest decrease in wound width occurred when switching from 0 to -75 mmHg. The level of negative pressure did not affect wound contraction (sternum bone: 32 ± 6 mm at -75 mmHg and 29 ± 6 mm at -175 mmHg, p = 0.0897). The decrease in lateral wound width during NPWT was greater in subcutaneous tissue (14 ± 2 mm) than in sternum bone (9 ± 2 mm), resulting in a ratio of 1.7 ± 0.3 (p = 0.0423), suggesting macro-deformation of the tissue. The anterior-posterior thicknesses of the soft tissue, at 0.5 and 2.5 cm laterally from the wound edge, were not affected by negative pressure.</p> <p>Conclusions</p> <p>NPWT contracts the wound and causes macro-deformation of the wound edge tissue. This shearing force in the tissue and at the wound-foam interface may be one of the mechanisms by which negative pressure delivery promotes granulation tissue formation and wound healing.</p

Prevalence of diffuse pancreatic beta islet cell disease with hyperinsulinism: Problems in recognition and management

Among 77 patients with endogenous hyperinsulinism seen in 2 medical centers, diffuse islet cell disease accounted for 17 (22%) patients. Since diffuse islet cell disease poses special problems in management, its prevalence is emphasized in this report. Among these patients with diffuse islet cell disease, there were 11 patients with adenomatosis, 4 with nesidioblastosis, and 2 with islet cell hyperplasia. Six of the 77 patients were found in multiple endocrine neoplasia, type I kindreds; diffuse islet cell disease was documented in 4 of these patients. We outline principles of management in patients with diffuse islet cell disease. Frozen section microscopy failed to identify nesidioblastosis or islet cell hyperplasia. Chez 77 malades, provenant de 2 centres médicaux, qui présentaient un hyperinsulinisme endogène, 17 cas de lésions diffuses des îlots de Langerhans ont été dénombrés. Ce fait est donc loin d'être exceptionnel et cette étude a pour but de le souligner. Parmi ces 17 malades, 11 présentaient des adénomes multiples (adénomatoses), 4 des nésidoblastomes (anomalies tissulaires multifocales), 2 des hyperplasies cellulaires insulaires. Chez ces 77 malades, 6 cas de MEN type I furent individualisés, 4 d'entre eux présentaient une maladie insulaire diffuse. Les auteurs, forts de cette expériences insistent sur les principes du traitement de ce type d'affection. Ils insistent sur le fait que l'étude histologique extemporanée ne permet pas d'identifier les nésidoblastomes et les hyperplasies cellulaires insulaires et que dans 70%–80% des cas les résections pancréatiques ne permettent pas d'obtenir la guérison. Un problema constante para el cirujano que opera pacientes con hiperinsulinismo endógeno es el de qué hacer cuando no se encuentre patología en el curso de la operación una vez realizada la exploración preliminar del páncreas. Los adenomas solitarios de células beta pueden pasar desapercibidos cuando no son palpables; la identificación de la enfermedad difusa de las células insulares plantea muchos problemas. Reconocemos tres alteraciones principales de tipo difuso: adenomatosis de células beta, nesidioblastosis e hiperplasia pancreática de células beta. Además, múltiples macroadenomas pueden coexistir o no con microadenomatosis o con hiperplasia en ciertos pacientes con hiperinsulinismo. Los desórdenes de células insulares de tipo multifocal son particularmente frecuentes en pacientes con Neoplasia Endocrina Multiple Tipo I.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41314/1/268_2005_Article_BF01654942.pd

Methodology of calculation of construction and hydrodynamic parameters of a foam layer apparatus for mass-transfer processes

Промислова реалізація методу стабілізації газорідинного шару дозволяє значно розширити галузь застосування пінних апаратів і відкриває нові можливості інтенсифікації технологічних процесів з одночасним створенням маловідходних технологій. У статті встановлені основні параметри, що впливають на гідродинаміку пінних апаратів, розглянуті основні конструкції та режими роботи пінних апаратів. Виявлено зв'язок гідродинамічних параметрів. Розглянуто гідродинамічні закономірності пінного шару. Вказані фактори, що впливають на процес масообміну, як в газовій, так і в рідкій фазах. Проведений аналіз ряду досліджень показав, що перспективним напрямком інтенсифікації процесу масообміну є розробка апаратів з трифазним псевдозрідженим шаром зрошуваної насадки складних форм із сітчастих матеріалів. Отже, необхідне проведення спеціальних досліджень гідродинамічних режимів роботи апарату з сітчастою насадкою і визначенням параметрів, що впливають на швидкість переходу насадки з одного режиму в інший.Industrial implementation of the stabilization method of the gas-liquid layer can significantly expand the field of use of foaming apparatus and opens up new opportunities for intensifying technological processes with the simultaneous creation of low-waste technologies. The article establishes the basic parameters influencing the hydrodynamics of foam apparatus, considers the basic constructions and operating modes of foam apparatus. The connection of hydrodynamic parameters is revealed. The hydrodynamic laws of the foam layer are considered. The indicated factors affecting the process of mass transfer, both in the gas and in the liquid phases. The conducted analysis of a number of studies showed that the perspective direction of intensification of the mass transfer process is the development of apparatuses with a three-phase fluidized bed of an irrigated nozzle of complex forms with mesh materials

Function of adult pig hearts after 2 and 12 hours of cold cardioplegic preservation

BACKGROUND: Most cardioplegic solutions have been developed using the classic Langendorf heart perfusion model, which only allows a short experimental follow-up. Our aim was to investigate hearts after prolonged storage by using a physiologic model including prolonged perfusion with normal, fresh blood. METHODS: Sixteen hearts from 60-kg pigs were preserved with dextran-enriched (dextran-40, 35 g/L) St. Thomas' solution for 2 or 12 hours after which they were continuously reperfused for 12 hours with normal blood, supplied by a support pig. A flexible balloon, fixed to an artificial valve apparatus connected to a circuit system, was inserted in the left ventricle for obtaining measurements of hemodynamic performance. RESULTS: During the first 3 to 4 hours of reperfusion there was no significant difference in left ventricular developed pressure, cardiac output, minute work output, or oxygen consumption between the two groups. After this time left ventricular developed pressure (p < 0.001), cardiac output (p < 0.01), minute work output (p < 0.01), and oxygen consumption were significantly lower in the 12-hour group. Coronary flow was higher (p < 0.01) and coronary vascular resistance lower (p < 0.01) during the first 5 to 6 hours of reperfusion in the 12-hour group. After 12 hours of reperfusion coronary vascular resistance was significantly higher (p < 0.01) in the 12-hour group. CONCLUSIONS: High-degree and long-lasting coronary hyperemia at the beginning of reperfusion can be a sign of unsatisfactory preservation of the heart. This investigation shows the importance of reperfusion with normal blood and a long follow-up period after postischemic reperfusion when studying the effect of cardioplegic solutions