Acta Physiol Hung
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Biography Historical Article
Poetry, physiology, and puerperal fever: understanding the young Oliver Wendell Holmes.
The 19th-century American physician Oliver Wendell Holmes (1809-1894) is known, internationally, more for his literary output than for his contributions to medical science. Yet a single paper he wrote in 1843--"The Contagiousness of Puerperal Fever"--has made him a hero in the eyes of many (especially in the United States) of the struggle against that scourge. ⋯ He was even as a young man a poet and a physiologist/anatomist as well as the author of this important essay. Whether and how those three features of Holmes's many-sides public persona are connected is discussed as a prelude to considering whether his work on puerperal fever legitimates his status as a medical hero.
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1. Although the increased heart rate variability in healthy subjects in association with slow patterned breathing and continuous positive airway pressure is well documented, there is no general agreement regarding the underlying mechanism. The arterial baroreceptor stimulation due to greater blood pressure variability, the stimulation of pulmonary stretch and low pressure baroreceptors can play important role in this phenomenon. 2. ⋯ The baroreflex sensitivity as calculated from spontaneous HR and BP sequences was 11.66 +/- 2.9 at baseline and increased to 17.66 +/- 6.1 and changed to 15.22 +/- 3.2 with the addition of patterned breathing and CPAP, respectively. 4. Our findings indicate that the heart rate and blood pressure responses to slow patterned breathing may be interpreted as consequences of an altered baroreflex sensitivity. In contrast the active breathing with CPAP exerts mechanical effects which in turn present an augmented systemic baroreflex trigger, however, the baroreflex sensitivity remains unchanged.
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Studies were carried out in anaesthetized dogs, to determine the effects of volume expansion induced by Ringer's solution, plasma taken from non-hydrated or previously volume expanded animals on the natriuretic response of the kidney. When the animals were infused with Ringer's solution (0.25 ml/kg/min iv.) water and sodium excretion increased gradually reaching a peak value at about 70 min. after starting the infusion (3.01 +/- 0.21 ml/min and 329 +/- 23.9 mmol/min, respectively). ⋯ We concluded, that besides the physical forces playing certainly a role mainly in the Ringer's solution hydrated dogs, some humoral natriuretic factor liberated in the volume expanded animals plays also a role in the diuretic-natriuretic response. This humoral factor can be released from the atria or other organs, but its production is not primarily regulated by intravasal volume/or pressure changes.
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Pulmonary arterial hypertension develops in acute respiratory failure and mostly an enhanced PADd-PCWP gradient has an important effect on the outcome of that complication. Considering that this critical state of septic burned patients may last for weeks, the long-term direct monitoring of pulmonary arterial blood pressure with indwelling Swan-Ganz catheter is impossible because of the high risk of endocarditis. Therefore, the aim of this study was to elaborate a noninvasive method to estimate the pulmonary arterial hypertension. ⋯ Close correlations have been found between PAPm and PO2/FiO2 (r = 0.75), as well as between PAP values and some noninvasively measured hemodynamic data. Using these interrelations: 1) regression equations for PAPs., PAPm, PAPd, PCWP, PVRI were elaborated (r values: 0.855, 0.869, 0.681, 0.644, 0.817 respectively); 2) discriminant analysis with noninvasive parameters correctly classified the cases at critical PAPd-PCWP gradient (greater than 4 mm/Hg) in 84%. These results suggest that a continuous noninvasive hemodynamic and blood gas monitoring completed with a periodic bedside computer analysis of the PC-processed data for calculation of the pulmonary arterial pressure may be enough for the therapy during the long-term critical periods.
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Comparative Study
Cough reflex in rabbits 24-h and 48-h after sulphur dioxide breathing.
The cough reflex elicitability (CRE), cough reflex strength (CRS) and Hering-Breuer inflation reflex (HBIR) were studied in 51 anaesthetized (Pentobarbital Spofa, 30 mg/kg, i.v.) female rabbits 24-h and 48-h after SO2 breathing. To provoke cough, the interior of the trachea and carina were stroked with a polyethylene catheter. To elicit the HBIR, the lungs were inflated to 1.0 kPa intratracheal pressure. ⋯ The CRE, CRS and HBIR obtained 24-h and 48-h after SO2 breathing were compared with correspondent values of control animals. It was found, that CRE and HBIR were fully recovered 24-h after SO2 breathing, but the CRS was still decreased, however, there were no significant differences in CRE, CRS and HBIR between animals 48-h after SO2 breathing and control animals. It can be concluded, that decrease of the CRS 24-h after SO2 breathing is not due to slowly adapting stretch receptors block of airways.