Orthostatic intolerance (OI), i.e., the inability to maintain stable arterial pressure during upright posture, is a major problem for astronauts after spaceflight. Therefore, one important goal of spaceflight-related research is the development of countermeasures to prevent post flight OI. Given the rarity and expense of spaceflight, countermeasure development requires ground-based simulations of partial gravity to induce appropriate orthostatic effects on the human body, and to test the efficacy of potential countermeasures. To test the efficacy of upright lower body positive pressure (LBPP) as a model for simulating cardiovascular responses to lunar and Martian gravities on Earth, cardiovascular responses to upright LBPP were compared with those of head-up tilt (HUT), a well-accepted simulation of partial gravity, in both ambulatory and cardiovascularly deconditioned subjects. Results indicate that upright LBPP and HUT induced similar changes in cardiovascular regulation, supporting the use of upright LBPP as a potential model for simulating cardiovascular responses to standing and moving in lunar and Martian gravities. To test the efficacy of a short exposure to artificial gravity (AG) as a countermeasure to spaceflight-induced OI, orthostatic tolerance limits (OTL) and cardiovascular responses to orthostatic stress were tested in cardiovascularly deconditioned subjects, using combined 70º head-up tilt and progressively increased lower body negative pressure, once following 90 minutes AG exposure and once following 90 minutes of -6º head-down bed rest (HDBR). Results indicate that a short AG exposure increased OTL of cardiovascularly deconditioned subjects, with increased baroreflex and sympathetic responsiveness, compared to those measured after HDBR exposure. To gain more insight into mechanisms of causal connectivity in cardiovascular and cardiorespiratory oscillations during orthostatic challenge in both ambulatory and cardiovascularly deconditioned subjects, couplings among R-R intervals (RRI), systolic blood pressure (SBP) and respiratory oscillations in response to graded HUT and dehydration were studied using a phase synchronization approach. Results indicate that increasing orthostatic stress disassociated interactions among RRI, SBP and respiration, and that dehydration exacerbated the disconnection. The loss of causality from SBP to RRI following dehydration suggests that dehydration also reduced involvement of baroreflex regulation, which may contribute to the increased occurrence of OI.

Dissertation (Ph.D.)--University of Toledo, 2009. / Typescript. "Submitted to the Graduate Faculty as partial fulfillment of the requirements for The Doctor of Philosophy Degree in Higher Education." Bibliography: leaves 274-302.

Amputation is the oldest surgical procedure recorded. In small animals, mainly dogs and cats, the goal of these procedures maintain the patient's life, when it is affected by lesions that progress to necrosis, malignancies, distal irreparable injury, and another one. The force platforms used to measure ground reaction forces involved inhuman and animal movement, allowing the interpretation of movement through mechanical variables. This study aims to analyse the distribution of weighting every limb and compare them with data from animals considered normal (with four limbs). It was studied 20 canines, divided into four groups: Group 1 (without the left forelimb), Group 2 (without the right forelimb), Group 3 (without the left hind limb) and Group4 (without the right hind limb). The animals evaluated within groups were not normal standard and they were above or below the upper and lower limits, because they had not one of the four members, adapting and transferring your weight to one of the other three members. It can be concluded that canines without the left forelimb band right forelimb transfer the weight to theirs contra lateral sides. Dogs that have not left forelimb transfer 76.99% of weight to the contra lateral side, as well as dog without right forelimb transferring 71.73% of weight to the contra lateral side. The canines that have not the left or right hind limbs, transfer weight to the forelimbs. / A amputação é o procedimento cirúrgico mais antigo registrado. Em animais de pequeno porte, principalmente cães e gatos, o objetivo desta cirurgia é manter a vida do paciente, quando acometido por lesões que evoluem para necrose, neoplasias malignas, lesões distais irreparáveis, dentre outras causas. A plataforma de força é utilizada para medir as forças de reação do solo envolvidas no movimento humano e animal, possibilitando a interpretação do movimento através de variáveis mecânicas. O presente estudo tem como objetivo analisar a distribuição de força em cada membro e comparar com os dados de animais, considerados normais, por possuírem quatro membros. Para isso, foram utilizados 20 animais, caninos divididos em quatro grupos: o Grupo 1 (sem o membro anterior esquerdo), o Grupo 2 (sem o membro anterior direito), Grupo 3 (sem o membro posterior esquerdo) e o Grupo 4 (sem o membro posterior direito). Todos os animais avaliados não estavam dentro dos padrões considerados normais, ou estavam acima ou abaixo dos limites superiores e inferiores, pois não tinham um dos quatros membros, adaptando-se e transferindo seu peso para os outros três membros. Dessa forma, pode-se concluir que os animais sem o membro anterior esquerdo e o membro anterior direito transferem seu peso para seu lado contralateral. Os cães que não possuem membro anterior esquerdo transferem 76,99% do seu peso para o lado contralateral, e os sem membro anterior direito transferem 71,73% do seu peso para o lado contralateral. O grupo de animais que não possui o membro posterior esquerdo ou direito, transfere seu peso para os membros anteriores.

Abstract available in the Faseb Journal

Cardiovascular responses and tolerance to an orthostatic stress were examined in eight men before and after eight months of endurance exercise training. Following training, maximal oxygen consumption and blood volume were increased, and resting heart rate reduced. Orthostatic tolerance was reduced following training in all eight subjects. It was concluded that prolonged endurance training decreased orthostatic tolerance and this decrease in tolerance appeared associated with attenuated baroreflex sensitivity and alterations in autonomic balance secondary to an increased parasympathetic tone noted with training.

Introduction Ehlers-Danlos syndrome (EDS), specifically the hypermobility type (hEDS), is associated with a variety of gastrointestinal (GI) conditions. This study aims to evaluate the prevalence of and factors associated with gut dysmotility in patients with hEDS. Methods This is a retrospective study of hEDS patients conducted at the Cleveland Clinic's Center for Personalized Genetic Healthcare between January 2007 and December 2017. Demographics, GI motility testing, endoscopic, and imaging data were extracted from the patients' charts. Results A total of 218 patients with hEDS were identified. Among them, 136 (62.3%) patients had at least one GI symptom at the time of EDS diagnosis. Motility testing was performed and reported in 42 (19.2%) patients. Out of them, five (11.9%) had esophageal dysmotility, 18 (42.8%) had gastroparesis, five (11.9%) had small bowel/colon altered transit time, and four (9.5%) had global dysmotility. In univariable analysis, patients with postural orthostatic tachycardia syndrome (POTS) [odds ratio (OR): 8.88, 95% CI: 3.69-24.9, p<0.0001], fibromyalgia (OR: 4.43, 95% CI: 2.04-10.1, p=0.0002), history of irritable bowel syndrome (OR: 5.01, 95% CI: 2.31-11.2, p<0.0001), and gastroesophageal reflux disease (OR: 3.33, 95% CI: 1.55-7.44, p=0.002) were more likely to be diagnosed with GI dysmotility. On multivariable analysis, only POTS (OR: 5.74, 95% CI: 2.25-16.7, p=0.0005) was significantly associated with an increased likelihood of GI dysmotility. Conclusions This study suggests that GI symptoms are relatively common among patients with hEDS. Of the patients tested for dysmotility, 76.2% were found to have some form of dysmotility. POTS was found to be an independent predictive factor for GI dysmotility.

Introduction - Pure autonomic failure is a rare disorder characterized by orthostatic hypotension, absence of a compensatory rise in heart rate, and abnormal autonomic functions. In most cases, supine hypertension is seen coupled with orthostatic hypotension, making the management of these patients a big challenge. We present the case of a 74-year-old gentleman, who presented to the ED with altered mental status for a day; weakness, and falls for 3 weeks. The patient had a past medical history of Hypertension, alcoholism, and REM sleep disorder. He was being treated for erectile dysfunction for the last 10 years and had a family history of Parkinson's disease in his mother and sister. The patient was compliant with Lisinopril 40 mg, Amlodipine, and Rosuvastatin, Tamsulosin 0.4 mg. His blood pressure(BP) on presentation was ranging between 109/74-194/76 mm of Hg. Systolic BP dropped by 30mmHg after tilting the angle of the bed to 45 degrees for 1 minute with no change in HR and the patient became symptomatic in this position. Orthostatic vitals showed a dramatic drop in Systolic BP of >80mmHg with no change in heart rate. MRA and MRI showed chronic microvascular changes. The Echocardiogram, Cortisol, and TSH levels were all normal. All anti-hypertensives were discontinued and supportive treatment was started with Midodrine, Droxidopa, and Pyridostigmine, thigh-high TED hose and abdominal binders at bedtime, and Nitroglycerin patch at night for hypertension. The patient was started on fludrocortisone as he continued to drop his BP by 80 mmHg on standing. The use of TED stockings and bed tilting improved the issue of uncontrolled supine hypertension at night. Conclusion- Treatment of autonomic dysfunction continues to be challenging. There are no definitive guidelines and management is largely individualized. Both pharmacological and non-pharmacological measures are used.

No description available.

Prolonged exposure to microgravity is known to invoke physiological changes which predispose individuals to orthostatic intolerance upon readaptation to the earth's gravitational field. Attenuated baroreflex responsiveness has been implicated in contributing to this inability to withstand orthostatic stress. To test this hypothesis, eight individuals were exposed to 15 days of simulated microgravity exposure using the 6° head-down bed rest model. Prior to, and after the simulated microgravity exposure, the following were assessed: a) aortic baroreflex function; b) carotid baroreflex function; c) cardiopulmonary baroreflex function; and d) the degree of interaction between the cardiopulmonary and carotid baroreflexes.

A lesão medular espinhal está entre as lesões mais graves que uma pessoa pode ter como experiência. Os efeitos pessoais e sociais são profundamente significantes, pois conferem uma incapacidade permanente sobre as pessoas acometidas. Quando acontece uma agressão à medula espinhal, ocorre um déficit na inervação abaixo da lesão, por perda do controle supraespinhal. Muitas são as conseqüências advindas das mudanças ocorridas na mecânica respiratória, conseqüente da lesão medular acima do sexto segmento torácico, como a superficialidade da respiração, ineficiência da tosse e do espirro, alterações do clearence mucociliar e aumento da complacência abdominal. Tais fatores promovem alterações nos volumes, capacidades e pressões respiratórias, dificultando aos indivíduos tetraplégicos e paraplégicos, com lesão torácica alta, serem colocados em pé, com auxílio de dispositivos, como a mesa ortostática. Com o intuito de verificar o efeito do uso da cinta abdominal elástica na função respiratória, em indivíduos lesados medulares, na posição ortostática em angulações de 60° e 60°/90°, foram mensurados, a capacidade vital, volume corrente, pressão inspiratória e expiratória máxima e saturação de oxigênio. Participaram 56 indivíduos, com predomínio do gênero masculino, apresentando média de idade de 35,4 anos e maior freqüência motora de lesão em T4. Estes foram divididos em quatro grupos distintos em relação ao uso ou não da cinta e angulações da mesa ortostática. Os resultados encontrados para os parâmetros avaliados, não demonstraram significância estatística em relação ao uso ou não da cinta abdominal elástica entre os grupos. No entanto, as médias dos grupos com o uso da cinta, apresentaram-se mais altas em todas as avaliações. Podemos considerar que a cinta não interferiu na melhora significativa dos parâmetros respiratórios. Porém, muitos indivíduos referem utilizá-la como um suporte abdominal, proporcionando estabilização na postura do tronco quando em pé. Estudos com ensaios clínicos aleatórios devem ser propostos para mensurar o efeito que a cinta abdominal elástica proporciona aos indivíduos lesados medulares que a utilizam freqüentemente durante o posicionamento ortostático. / Spinal cord injury is one of the most severe injuries that someone can experience. The personal and social impacts are deeply significant as they cause a permanent disability to the injured person. When the spinal cord injury takes place it results in anervous deficit below the injury site by loss of upper spinal control. There are many consequences of the changes to the respiratory biomechanics, due to the injury above the sixth thoracic segment, such as the superficial respiratory capacity, cough and sneeze inefficiency, mucociliary clearance changes and abdominal complacence increase. These complications cause volume, capacity and pressure disturbances that make it difficult to put tetraplegic and paraplegic individuals with high thoracic injury into a standing up position, even with the assistance of devices like the orthostatic table. The vital capacity, the tidal volume, the maximum inspiratory and expiratory pressures and the oxygen saturation were measured to ascertain the effect of the elastic abdominal binder to the respiratory function of individuals with spinal cord injury at the orthostatic position on 60º and 60º/90º angulations. 56 individuals were chosen, mostly men, at the average age of 35.4 and higher motor frequency injury at the T4. They were divided into four different groups according to the binder use and the orthostatic table angulation’s. Results did not show statistic significance to using or not using the binder between the groups. However, the averages of the groups that used the binder were the highest in all the measurements. It can be said that the binder did not interfere to the significant improvement of the respiratory patterns. In spite of that, many people say they prefer to use the binder as an abdominal support that provides stability to the body when they are standing up. Randomized clinic studies should be done to measure the elastic abdominal binder effects provided to the individuals with spinal cord injuries that often use it into the orthostatic position.