A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Bedside ultrasound of the inferior vena cava (IVC) has grown to be an important tool in the assessment and management of critically ill patients. This study endeavors to examine which location along the IVC is most highly correlated with changes in intravascular volume status: (1) the diaphragmatic juncture (DJ) (2) two centimeters caudal to the hepatic vein juncture (2HVJ) or (3) left renal vein juncture (LRVJ). Data was collected in this prospective observational study on patients in the emergency department who were at least 16 years of age, being treated with intravenous fluids (IVF). Measurements of the IVC were recorded at each site during standard inspiratory and expiratory cycles, and again with the patient actively sniffing to decrease intrapleural pressures. IVF was then administered per the patient’s predetermined treatment, and the same six measurements were repeated after completion of fluid bolus. The difference in caval index (dCI) was calculated for all six data sets and correlated with the mL/kg of IVF administered. There was a statistically significant correlation between mL/kg of IVFs administered and dCI at all three sites (DJ: r = 0.354, p value = 0.0002; 2HVJ: r = 0.334, p value = 0.0003; LRVJ: r = 0.192, p value = 0.03). The greatest correlation between amount of fluids administered and dCI was observed along the IVC at the site 2 cm caudal to the juncture of the hepatic veins (2HVJ). This site is also where the largest change in diameter can be appreciated on ultrasound during intravascular volume resuscitation. Our data also suggests that every mL/kg of IVFs administered should change the dCI by 0.86-1.00%. This anticipated change in IVC diameter can be used to gauge a patient’s response to intravascular volume repletion.

The purpose of this thesis was to investigate the role of lactate in the regulatory volume response of mammalian skeletal muscle to hypertonic challenge-induced cell shrinkage. It was demonstrated that adult mice skeletal muscle single fibres responded to increased extracellular osmolarity in a dose-dependent manner when exposed to NaCl or sucrose challenge. This regulatory response to sucrose and NaCl however was abolished when cells were pre-treated with bumetanide, a specific sodium-potassium-chloride cotransport (NKCC) inhibitor, demonstrating that the NKCC is primarily responsible for eliciting a regulatory volume increase (RVI). When cells were exposed to NaLac treatment, bumetanide incubation did not significantly diminish the ability of the cells to recover volume. Furthermore, these cells lost less volume compared to NaCl or sucrose control. Inhibiting the single muscle fibres with either monocarboxylate transport (MCT) inhibitor phloretin or pCMBS resulted in significantly greater volume loss and impaired volume recovery. Combined MCT inhibition of phloretin or pCMBS with NKCC inhibition (bumetanide) led to unexpected findings, whereby the cells lost very little volume. These data suggest that while skeletal muscle fibres may utilize the NKCC to regulate volume, the ability for these cells to employ the most efficient means of volume regulation involves the inclusion of lactate as well via MCT uptake. / NSERC

No description available.

The study was conducted to determine if learnings of spatial perception can be increased by the utilization of motion information experiences as measured by perceptual tests of voluminality and visualization. Perceptual change was specifically examined regarding the use of depth in paper sculpture production and the use of spatial relations in figure-completion tasks.The study's research design consisted of 77 white, lower-middle-class, fourth-grade subjects used as intact classroom groups of two pretest-posttest treatment groups, one pretest-posttest control group and one posttest-only control group.Two experimental treatments incorporating different instructional methods were implemented to promote perceptual change in subjects. One treatment provided for motion information experiences by depicting continuously changing views of several sculptures in a motion picture film. The motion information treatment also contained a monocular depth cue explanation which was applied to the film and assisted by manipulating the film projector's action. The treatment was contrasted with another which utilized stationary information presented in photographicslides indicating three views of each filmed sculpture. Since this stationary information treatment used the same procedures regarding depth cue instruction and discussion, it served to isolate the motion variable found in the other treatment. The pretest-posttest control group received no treatment but the posttest-only control group experienced the same visual and verbal communication contained in the motion information treatment.The instruments that measured pretest and posttest achievement were a Voluminal Form Test (VFT) devised by the investigator and the Spatial Relations Test (SRT) from the Primary Mental Abilities series. The former test was used by trained judges to determine the degree of voluminality displayed in sculptures produced by the research subjects. Subject's visualization ability was measured by the standardized SRT.The nonrandomized subject's scores were processed by an analysis of covariance procedure that adjusted the respective posttest group means of the pretested groups. The adjusted means were then utilized in t tests. An analysis of variance procedure was also conducted between the unadjusted posttest means of the motion information treatment group and the posttest-only control group.Results of the t tests that used VFT and SRT scores indicated nonsignificant differences existed between the three pretested groups. The differences between the motion information treatment and the unpretested control groups were also not significant, judging by ANOVA's results. These results were found regarding both voluminality and visualization data.Based on the conditions, methods and findings in the study, four conclusions were inferred concerning hypothesized change in subject's spatial perception as demonstrated in either sculpture production or visualization test performance.1. Visual motion information experiences analyzed through monocular depth cue utilization training did not affect greater spatial perception than did identical training using stationary information experiences.2. Improved spatial perception was not more affected by visual motion information experiences analyzed through monocular depth cue utilization training than by a nonvisual information-and-training experience.3. Training consisting of visually stationary information experiences analyzed through monocular depth cue utilization did not affect increased spatial perception as compared to such effects associated with a nonvisual information-and-training experience.4. When analyzed through monocular depth cue utilization training, pretested visual motion information experiences did not affect greater spatial perception than did nonpretested, but otherwise identical, motion information experiences.Due to possible validity threats from an irregularity in the procedures and the use of nonrandomized subjects, the last conclusion regarding pretest sensitization was most cautiously offered.

Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 125-127).

Submitted by Reginaldo Soares de Freitas (reginaldo.freitas@ufv.br) on 2016-10-27T16:54:14Z No. of bitstreams: 1 texto completo.pdf: 1922256 bytes, checksum: fbc0e5d6abb2de493797e4cbb525d8e9 (MD5) / Made available in DSpace on 2016-10-27T16:54:14Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1922256 bytes, checksum: fbc0e5d6abb2de493797e4cbb525d8e9 (MD5) Previous issue date: 2002-03-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A obesidade é uma patologia multicausal, considerada, atualmente, como um dos principais problemas de saúde pública. Sua prevalência vem crescendo muito nas últimas décadas alcançando índices alarmantes no Brasil e no mundo. Independente de fatores associados com predisposição genética, essa patologia está sempre acompanhada de distúrbios na ingestão alimentar e de alto consumo de refeições com alta densidade energética e com o sedentarismo. Deste modo, a obesidade ocorre quando se tem uma perda de equilíbrio entre a ingestão alimentar e o gasto energético. Tendo em vista esses aspectos este trabalho avaliou o efeito do volume de iogurte convencional e light e convencional, independente de outras variáveis, sobre os parâmetros de ingestão alimentar usando incorporação de ar em iogurte convencional e light por adição de um produto comercialmente disponível – Emustab – (6g/300mL) com posterior homogeneização em liqüidificador semi-industrial. Utilizaram-se três volumes de ambos iogurtes 300, 450 e 600 mL. Trabalhou-se com 40 participantes saudáveis, sendo 20 eutróficos, Índice de Massa Corporal (IMC) entre 19 e 24.9 Kg/m2, e 20 com excesso de peso (IMC ≥ 25 Kg/m2). Os participantes receberam cada volume de iogurte em três diferentes dias pela manhã em jejum de 12 horas. A escala de analogia visual (VAS) foi utilizada para avaliar sensações subjetivas de fome e desejo por alimentos específicos. Os volumes dos iogurtes convencional e light afetaram a saciedade dos dois grupos estudados, sendo que o maior volume exerceu melhor essa ação (p < 0,01). O maior escore para fome foi detectado após ingestão do volume de 300 mL seguido de 450 e 600 mL (p < 0,01). O desejo por alimentos doces, salgados, gordurosos e tira-gosto foi influenciado pelo tempo e volume dos iogurtes para ambos os grupos (p < 0,01). A ingestão energética subsequente ao experimento não diferiu estatisticamente entre os dias do estudo e o dia sem iogurte (p < 0,05). O resultado desse estudo sugere que o volume de iogurte light e convencional, independente de outras variáveis, pode afetar fome e saciedade. / Obesity is a multi-causal pathology currently considered one of the main problems in public health. It has become increasingly prevalent in the last decades, reaching alarming indexes in Brazil and worldwide.Regardless of the factors associated with genetic predisposition, this pathology is consistently associated with abnormal food intake, combined with high consumption of highly energetic food and sedentary habits. Thus, obesity is the result of an imbalance between food intake and energy spenditure. Based on these aspects, this work evaluated the effect of volume on food intake independent of other variables, using incorporated air in light and traditional yogurt. Three volumes of yogurt were used: 300, 450 and 600 mL. Forty healthy subjects participated of this study, divided in 2 groups, 20 overweight (BMI ≥ 25 kg/m2) and 20 normal weight (BMI 19 a 24.9 kg/m2). The subjects received each volume of the yogurt in three different days in the morning after 12 hours fasting. The Visual Analogy Scale (VAS) was used to assess appetite sensations. The highest score for hunger was detect after 300 mL followed 450 and 600 mL, respectively (p < 0.01). The volume of light and traditional yogurt affected the satiety in both groups, and the largest volume had a great effect (p < 0.01). The time and volume of the yogurts, in both groups, affected the appetite for sweet, salty, savoury and fatty foods (p < 0,01). The volume did not show a significant effect in the sensorial attributes of the yogurt. The results from this study suggest that the volume of the light and traditional yogurt, independent of other factors, may influence the appetite and satiety.

FREIRE, Caio César Furtado. Efeitos da hipovolemia aguda leve no esvaziamento gástrico e na distribuição intra-gástrica de líquidos em humanos sadios. 2008. 119 f. Dissertação (Mestrado em Farmacologia) - Universidade Federal do Ceará. Faculdade de Medicina, Fortaleza, 2008. / Submitted by denise santos (denise.santos@ufc.br) on 2012-03-07T13:53:53Z No. of bitstreams: 1 2008_dis_ccffreire.pdf: 517149 bytes, checksum: f64a203e901d10c4b114e3fb78e3dc37 (MD5) / Approved for entry into archive by Eliene Nascimento(elienegvn@hotmail.com) on 2012-03-08T11:26:23Z (GMT) No. of bitstreams: 1 2008_dis_ccffreire.pdf: 517149 bytes, checksum: f64a203e901d10c4b114e3fb78e3dc37 (MD5) / Made available in DSpace on 2012-03-08T11:26:23Z (GMT). No. of bitstreams: 1 2008_dis_ccffreire.pdf: 517149 bytes, checksum: f64a203e901d10c4b114e3fb78e3dc37 (MD5) Previous issue date: 2008 / Preliminary researches have shown that acute mild hypovolemia reduces tonus and increases gastric compliance in healthy humans. (Macedo et. al, Neurogastroenterol Mot, 2005). Aims: Then we purposed to investigate if, despite a mild hypovolemia, blood donation was able to delay gastric emptying and modify intragastric distribution of a liquid test meal in healthy volunteers. Methods: We studied 14 healthy men volunteers (median age 23 years and body mass index 24.1 kg/m2). After an overnight fast (8-10h), volunteers underwent randomized and paired studies on separate moments (7 to 21 days). After beginning of mean blood pressure and heart rate monitoration, they were submitted to venous punction followed (experimental condition) to a standard blood letting (up to 450-mL) or not (control condition). Next, they ingested 500-mL of the test meal (5% glucose solution labelled with 37MBq of Tecnecium - 99mTc). Serial images of the gastric area in anterior and posterior projections were taken by a gamma camera throughout 60 minutes. After definition of regions of interest for proximal, distal, and total stomach, the activity time curves were derived from geometric means of anterior and posterior counts. Statistical analysis was performed by paired “t” test. Results: There is no significant difference of hemodynamic parameters between experimental and control conditions. In comparison with the respective control values, hypovolemia increased significantly the total stomach retention since 20 min (69.8 ± 2.9 vs 62.3 ± 2.3%) until 60 min (35.1 ± 2.1% vs 28.2 ± 2.9%) after intake meal (P<0,05). The t1/2 values obtained after bleeding (39.1±3.5min) were greater than those in control (30.8±2.6min) (P<0,05). In comparison with the respective control values, hypovolemia increased significantly the proximal stomach retention since 25 min (38.6±2.4 vs 31.2±2.2 %), until 60 min (18.6±1.2 vs 12.3±1.9%) after intake meal (P<0.05). There is no significant difference in distal stomach retention between both conditions. Conclusions: Besides mild hypovolemia, blood donation delays total gastric emptying and increases proximal gastric retention of a liquid meal in healthy volunteers. / Estudos preliminares mostraram que a hipovolemia aguda leve reduz o tônus e aumenta a complacência gástrica em humanos sadios. (Macedo et. al, Neurogastroenterol Mot, 2005). Objetivos: Assim, propomos investigar se, apesar de causar uma hipovolemia leve, a doação sanguínea seria capaz de retardar o EG e modificar a distribuição intra-gástrica de uma refeição teste líquida em voluntários sadios. Métodos: Estudamos 14 voluntários homens sadios (medianas de idade = 23 anos e de índice massa corporal = 24,1 kg/m2). Após 8 a 10 horas de jejum, mediante sorteio os indivíduos foram submetidos a estudos pareados em diferentes momentos (intervalo de 7 a 21 dias). Após inicio da aferição da pressão arterial e freqüência cardíaca, os indivíduos foram submetidos à punção venosa, seguida (condição experimental) de sangria padrão (aproximadamente 450-ml de sangue) ou não (condição controle). A seguir, houve a ingestão da refeição teste (500-ml de solução de glicose a 5% marcado com 37MBq de Tecnécio-fitato - 99mTc). Imagens seriadas da área gástrica em projeções anterior e posterior foram obtidas por uma gama-câmara durante 60 minutos. Após a definição das regiões de interesse do estômago proximal, distal e total, as curvas de atividade por tempo foram derivadas de médias geométricas de contagens das regiões anteriores e posteriores. A análise estatística foi realizada pelo teste “t” pareado Resultados: Os resultados de parâmetros hemodinâmicos não mostraram diferença estatística entre a condição controle e sangrado. Em comparação com os respectivos valores de controle, a hipovolemia aumentou significativamente a retenção refeição teste no estômago desde 20 minutos (69.8 ± 2.9 vs 62.3 ± 2.3%) até 60 minutos (35.1 ± 2.1% vs 28.2 ± 2.9%) depois da refeição (P<0,05). Na condição sangrado, o valor de t1/2 (39,1 ± 3,5 minutos) foi significativamente maior (P < 0,05) em relação à condição controle (30,8 ± 2,6 minutos) (P<0,05). Em comparação com os respectivos valores de controle, a hipovolemia aumentou a retenção da refeição teste no estômago proximal desde 25 minutos (38,6 ± 2,4% vs 31,2 ± 2,2%; P<0,05) até 60 minutos (18,6 ± 1,2% vs 12,3 ± 1,9%); após a ingestão da refeição (P<0,05). Não houve diferença significativa de contagem no segmento distal entre as condições. Conclusão: Apesar de hipovolemia leve, doação de sangue retarda o esvaziamento gástrico total e aumenta retenção gástrica proximal de refeição líquida em voluntários saudáveis.

PALHETA JÚNIOR, Raimundo Campos. A distensão mecânica atrial direita diminui a complacência gástrica em ratos normovolêmicos anestesiados. 2006. 91 f. Dissertação (Mestrado em Farmacologia) - Universidade Federal do Ceará. Faculdade de Medicina, Fortaleza, 2006. / Submitted by denise santos (denise.santos@ufc.br) on 2012-05-09T16:01:43Z No. of bitstreams: 1 2006_dis_rcpjunior.pdf: 506057 bytes, checksum: ce2d477c8dac2509783864b5c0c7f538 (MD5) / Approved for entry into archive by Eliene Nascimento(elienegvn@hotmail.com) on 2012-05-14T16:02:01Z (GMT) No. of bitstreams: 1 2006_dis_rcpjunior.pdf: 506057 bytes, checksum: ce2d477c8dac2509783864b5c0c7f538 (MD5) / Made available in DSpace on 2012-05-14T16:02:01Z (GMT). No. of bitstreams: 1 2006_dis_rcpjunior.pdf: 506057 bytes, checksum: ce2d477c8dac2509783864b5c0c7f538 (MD5) Previous issue date: 2006 / Graça et al. (2002) observou em ratos que a hipervolemia aumenta o tônus gástrico, enquanto a hipovolemia o diminuía. Resolvemos estudar o efeito do estiramento cardíaco sobre o tônus gástrico e os mecanismos neurais envolvidos. Metodologia: Ratos albinos machos (n=82, ~320g), anestesiados, com vasos cervicais canulados para registros hemodinâmicos e distensão do átrio (DA). Um grupo separado de animais foi submetido à vagotomia subdiafragmática (DAIV) ou esplancnotomia (DAV). Para registro do volume gástrico (VG), foi introduzido per os um cateter com um balão de látex posicionado no estômago proximal e acoplado a um pletismômetro. Após período basal (15min), os ratos foram submetidos aos protocolos: falso distendido (FDA) ou animais submetidos durante 5 min à DA com 30, 50 ou 70µL, respectivamente (DAI), (DAII) e (DAIII), ou (DAIV) e (DAV) submetidos a DA com 50µL. Em seguida, houve monitoração nos 30min seguintes, divididos em intervalos de 10 min, designados de D10, D20 e D30. Os dados relativos ao VG estão representados em percentagem de seus respectivos valores basais. Sendo analisados por ANOVA seguida do teste de Bonferroni. Resultados: Não houve variações do VG e PVC no grupo FDA, porém no grupo DAI houve uma diminuição significativa do VG em D20 e D30 (9.9% e 14%, respectivamente), não houve aumento da PVC durante a DA. Nos grupos DAII e DAIII o VG diminuiu a partir de D10 (5% e 5.8%, respectivamente, p<0,05) com persistência em D20 (8,5 e 13%,respectivamente) e D30 (11,5 e 16,5%, respectivamente). Além disso, a PVC aumentou em ambos os grupos durante a DA (p< 0,05). No grupo IV, a vagotomia preveniu a diminuição do GV, permanecendo inalterado o VG durante o período experimental. No grupo V, a esplancnotomia aumentou tal efeito, o VG diminuiu a partir de D10 (10,5%, p<0,05) se intensificando em D20 e D30 (16 % e 23,4%, respectivamente). Conclusão: A distensão do balão atrial além de desencadear ajuste hemodinâmicos diminui o VG em ratos anestesiados, efeito abolido após vagotomia subdiafragmática, e permanecendo acentuado nos animais esplancnotomizados

FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Este trabalho tem como principal objetivo estudar as mÃtricas do funcional volume, volume mÃnimo e curvatura mÃnima em variedades compactas de dimensÃo quatro. Na primeira parte o objetivo à investigar as mÃtricas crÃticas do funcional volume sob a condiÃÃo de tais mÃtricas serem Bach-flats em uma variedade compacta com bordo &#8706;M. Provamos que uma mÃtrica crÃtica do funcional volume Bach-flat em uma variedade simplesmente conexa de dimensÃo quatro com bordo isomÃtrico a uma esfera padrÃo à necessariamente isomÃtrico a uma bola geodÃsica em um espaÃo forma simplesmente conexo R4, H4 ou S4. AlÃm disso, mostramos que em dimensÃo trÃs o resultado continua valido substituindo a condiÃÃo Bach-flat pela condiÃÃo mais fraca de M ter o tensor de Bach harmÃnico. Na segunda parte estudamos os invariantes geomÃtricos: volume mÃnimo e curvatura mÃnima. Em 1982, Gromov introduziu o conceito de volume mÃnimo para uma variedade suave como sendo o Ãnfimo de todos os volumes sob as mÃtricas de curvatura seccional limitada, em valor absoluto, por 1. Enquanto a curvatura mÃnima, que foi introduzido por Yun, à o menor pinching da curvatura seccional dentre as mÃtricas de volume 1. Em ambos os casos damos estimativas inferiores envolvendo alguns invariantes diferenciÃveis e topolÃgicos. Dentre elas mostraremos exemplos em que as estimativas sÃo Ãtimas. AlÃm disso, obtemos uma caracterizaÃÃo para o caso da igualdade em algumas estimativas. / This aim of this is to study the critical metrics of the volume functional, minimal volume and minimal curvature on four-dimensional compact manifolds. In the first part, we investigate Bach-flat critical metrics of the volume functional on a compact manifold M with boundary &#8706;M. Here, we prove that a Bach-flat critical metric of the volume functional on a simply connected 4-dimensional manifold with boundary isometric to a standard sphere must be isometric to a geodesic ball in a simply connected space form R4, H4 or S4. Moreover, we show that in dimension three the result even is true replacing the Bach-flat condition by the weaker assumption that M has divergence-free Bach tensor. In the second part we investigate the geometric invariants: minimal volume and minimal curvature. In 1982, Gromov introduced the concept of minimal volume for a smooth manifold as the greatest lower bound of the total volumes of Mn with respect to complete Riemannian metrics whose sectional curvature is bounded above in absolute value by 1. While the minimal curvature, introduced by G. Yun in 1966, is the smallest pinching of the sectional curvature among metrics of volume 1. In both cases we give below estimates to minimal volume and minimal curvature on 4-dimensional compact manifolds involving some differential and topological invariants. Among these ones, we get some sharp estimates. Moreover, we deduce characterizations for the equality case in some estimates.

A colheita mecanizada florestal é uma atividade custosa com diversos fatores a serem gerenciados e controlados para que se torne uma atividade viável e competitiva. Para a aplicação em povoamentos florestais de baixo volume por hectare, a escolha do sistema de colheita ideal é fator determinante para o sucesso operacional e financeiro do processo. O presente estudo avaliou dois sistemas de colheita: um convencional - composto por: \"Harvester\" e \"Forwarder\" - e outro alternativo - composto por: \"Feller-buncher\", \"Skidder\", \"Flail\", \"Power-Clamp\" e \"Garra-Traçadora\". Os sistemas de colheita foram aplicados em florestas de baixo volume unitário, sendo a UP-A com 0,14 m³.árv.-1 com 48,07 hectares e a UP-B com 0,11 m³.árv.-1 com 80,88ha. Foi realizado estudo de tempo contínuo para o apontamento dos indicadores de desempenho de disponibilidade mecânica, eficiência operacional e índice de utilização, bem como coleta do número de árvores produzidas por cada máquina de cada um dos sistemas em ciclos de 30min. de forma aleatória. Os custos horários foram divididos em: custos fixos - compostos por: custo de depreciação, juros, seguros e estrutura - e custos variáveis - representados pelos valores correspondentes a: combustível, lubrificantes, mão de obra e manutenção. O custo de produção (R$.m-3 de cada máquina e somatório de cada sistema) foi obtido por meio da soma dos custos fixos e variáveis de cada máquina e divisão entre sua produção horária apontada pelos técnicos florestais ao longo do estudo. Na análise estatística, aplicou-se o teste de BOX-COX para avaliar a homogeneidade da variância da produção horária (m³.h-1) com a variância homogeneizada pela transformação logarítmica, fez-se a análise de variância (ANOVA) da variável m³.h-1 de cada um dos sistemas para cada uma das unidades de produção e, sequencialmente, realizou-se o teste de comparação de médias dos sistemas de colheita e unidades de produção, comparados pelo teste de Tukey a 5%. Os custos fixos do sistema convencional totalizaram 221,59 R$.h-1, sendo estes 52,77% dos custos totais deste sistema, já o sistema alternativo apresentou um custo total fixo de 668,55 R$.h-1, representando 45,75% dos custos totais horários. Os custos variáveis do sistema convencional totalizaram 198,29 R$.h-1, compondo 47,23% dos custos totais, e para o sistema alternativo, os custos variáveis totalizaram 792,68 R$.h-1, representando 54,25% dos custos totais. O custo de produção do sistema convencional na UP-A foi de 19,38 R$.m-³ e na UP-B foi de 23,85 R$.m-³. Já para o sistema alternativo, obteve-se na UP-A um custo de 14,62 R$.m-³ e para UP-B um valor de 19,99 R$.m-³. Em conclusão, verificou-se que, para ambas as situações de floresta estudadas, o sistema alternativo de colheita foi mais competitivo em relação ao sistema convencional. / The forest mechanized harvesting operation is a costly activity with many factors to be managed and controlled in order to become a viable and competitive activity. Thus when applied to forest stands with low volume per hectare, choosing the ideal harvesting system is a determining factor for the operational and financial success. The present study analyzed two harvesting systems, one named traditional, which is composed of \"Harvester\" and \"Forwarder\" and a second named alternate consisting of \"Feller-buncher\", \"Skidder\", \"Flail\", \"Power-Clamp\" and \"Grapple-Saw\". Both systems were applied to harvest forests of low unit volume, and the UP-A with 0.14 m³.tree-1 with 48.07 hectares and UP-B with 0.11 m³.tree-1 with 80.88 hectares. The study was conducted with continuous time for the appointment of the performance indicators of mechanical availability, operational efficiency and utilization rates, also was collected the number of trees produced by each machine in each system in cycles of 30 minutes at random. Hourly costs were divided into fixed costs, consisting of depreciation cost, interest, insurance and variable cost structure was represented by the cost of fuel, lubricants, labor and maintenance. The production cost of R$.m-3 of each machine and the sum of each system was obtained by the sum of the fixed and variable costs of each machine and divided by their hourly production indicated by forest technicians throughout the study. Statistical analysis was applied to the BOX-COX test to evaluate the homogeneity of the variance of output per hour (m³.hour-1), with the variance homogenized by logarithmic transformation was made the variance analysis (ANOVA) of the variable m³.hour-1 of each harvest system for each forest production units and sequentially held the mean test comparison of harvest systems and forest production units, compared by Tukey test at 5%. The fixed costs of the traditional system totaled R$ 221.59 per hour effective worked these being 52.77% of the total costs of the system, since the alternative system presented a total fixed cost of R$ 668.55 per effective worked hour, representing 45.75% of the total costs. The variable costs of the traditional system totaled R$ 198.29 per effective worked hour, composing 47.23% of total costs, and for the alternative system, variable costs totaled R$ 792.68 per worked hour effectively representing 54.25% of total costs. The production cost of the traditional system in UP-A was R$ 19.38 per m³ and UP-B of R$ 23.85 per m³, for the alternative system has obtained in the UP-A a cost of R$ 14.62 per m³ and for the UP-B R$ 19.99 per m³. It is concluded that for both situations of forests studied, the alternative harvest system was more competitive compared to the traditional system in terms of R$.m-3.