Cardiovascular responses to hypoxemia and acidemia in fetal lambs

Cohn, Herbert E.; Sacks, Edmond J.; Heymann, Michaël; Rudolph, Abraham M.

doi:10.1016/0002-9378(74)90587-0

Cited by 760 publications

(344 citation statements)

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“…These are important adjustments to the fetus in terms of maintaining sufficient blood flow to the site of oxygenation and supplying adequate oxygen to vital organs. The distribution of combined ventricular output during fetal hypoxemia differs somewhat from the distribution during vasopressin infusion (Cohn et al, 1974). The proportion of combined ventricular output distributed to the placenta, coronary, and cerebral circulations increases in both instances.…”

Section: Discussionmentioning

confidence: 84%

“…The proportion of combined ventricular output distributed to the placenta, coronary, and cerebral circulations increases in both instances. Vasopressin infusion causes a great reduction in blood flow to the peripheral circulation and gut, whereas hypoxemia has no effect, although combined hypoxemia and acidemia result in a decrease in flow to these circulations (Cohn et al, 1974). Blood flow to the adrenals, kidneys, and lungs was not changed during vasopressin infusion, whereas hypoxemia significantly alters flow to these areas.…”

Section: Discussionmentioning

confidence: 91%

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Hemodynamic responses of the sheep fetus to vasopressin infusion.

Iwamoto¹,

Rudolph²,

Keil³

et al. 1979

Circulation Research

142

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SUMMARYThe effects of intravenous infusion of vasopressin on the circulation of the fetus were studied in lambs in utero with chronically maintained intravascular catheters. Vasopressin infused in doses of 0.91-2.26 mU/min per kg fetal weight resulted in plasma levels of arginine vasopressin of 6.8-36.4 /iU/ml; these levels are similar to those achieved during fetal hypoxia. Petal mean arterial blood pressure increased from control levels of 47 ± 1.7 to 56 ± 1.9 nun Hg, and heart rate fell from 174 ± 4.1 to 144 ± 4.4 beats/min. Fetal cardiac output and its distribution and actual organ blood flows were measured before and during vasopressin infusion by the radionuclide-labeled microsphere technique. Combined ventricular output did not change significantly, but there was a redistribution of flow, with a marked reduction of the proportion of cardiac output to the gastrointestinal and peripheral circulations and an increase in the percent of cardiac output to the umbilical-placental, myocardial, and cerebral circulations. This redistribution was associated with a significant increase in fetal arterial Po» from 22 to 24 torr. Changes in heart rate, cardiac output, and distribution of cardiac output to various fetal organs are similar to those seen during fetal hypoxia and suggest that vasopressin release may play an important role in the fetal cardiovascular response to stress. ORE Res 44: 430-436, 1979 ARGININE VASOPRESSIN has been detected in the neurohypophysis (Alexander et al., 1974a;Skowsky and Fisher, 1977; Vizsolyi and Perks, 1976a, b) and plasma (Rurak, 1975;Skowsky et al., 1974) of fetal sheep by midgestation. It is not known, however, whether arginine vasopressin has a role in normal fetal physiology or in the fetal response to stressful stimuli. Plasma concentrations of arginine vasopressin in the sheep fetus have been shown to be elevated in response to various stimuli such as fetal hemorrhage, hypoxia, increased plasma sodium, and surgical manipulation (Alexander et al., 1974a, b;Rurak, 1975;Skowsky et al., 1973;Alexander et al., 1972).The cardiovascular system of the fetus responds to neurohypophysial hormones; intravenous infusion of arginine vasopressin into the sheep fetus has been shown to cause an increase in blood pressure and a decrease in heart rate (Rurak, 1975;Alexander et al., 1976). At present there is no information regarding the specific actions of arginine vasopressin on the cardiovascular system of the fetus. It is known that, in the adult, arginine vasopressin causes bradycardia and vasoconstriction of certain vascular beds, resulting in an increase in blood pressure (Vizsolyi and Perks, 1976a;Altura and Altura, 1977;Schmid et al., 1974). Our studies were undertaken to determine whether these responses are present in the fetus, and to characterize further the action of vasopressin on the hemodynamics of the sheep fetus. The nuclide-labeled microsphere method (Rudolph and Heymann, 1967;Heymann et al., 1977) was used to determine the distribution of combined ventricular output to v...

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 91%

Hemodynamic responses of the sheep fetus to vasopressin infusion.

Iwamoto¹,

Rudolph²,

Keil³

et al. 1979

Circulation Research

142

View full text Add to dashboard Cite

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“…The method used to promote asphyxia in this study was based on a previous study using a plastic bag to obtain this experimental condition 28 and it seemed reliable because it reproduces bradycardia as reported in literature 29 which induces an initial increase in waking 30 . The recovery of neonatal rats after 60 minutes of asphyxia cannot be attributed to methodological inadequacy because their high resistance is well documented 31 .…”

Section: Discussionmentioning

confidence: 99%

Compensatory rebound of body movements during sleep, after asphyxia in neonatal rats

Suarez

Hoshino

2008

Acta Cir. Bras.

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Purpose:The usefulness of body movements that occur during sleep when assessing perinatal asphyxia and predicting its longterm consequences is contradictory. This study investigated whether neonatal rats manifest these movements in compensatory rebound after asphyxia, and if these alterations play an important role in its pathogenesis. Methods: Eight neonatal rats (aged 6-48h) were implanted with small EMG and EKG electrodes and sleep movements were recorded over a 30-minute control period. Recordings were continued during asphyxia caused by the enclosure of the animal in a polyvinyl sheet for 60 minutes, followed by a 30-minute recovery period. Results: Heart rate was lowered to bradycardic level during asphyxia causing behavioral agitation and increased waking time during the initial phase (30 minutes). Sleep-related movements were also significantly reduced from 12.5 ± 0.5 (median ± SE/2min) to 9.0 ± 0.44 in the final half of the period (Anova, p<0.05). Movement frequency increased in the recovery period to 15.0 ± 0.49 (Anova, p<0.05). Conclusion: These data show that newborn rats present compensatory rebound of body movements during sleep which may help in the diagnosis of asphyxia and other problems related to sleep parameters. Key words: Sleep. Infant, Newborn. Asphyxia. Motor Activity. Rats. RESUMO Objetivo:A utilidade dos movimentos corporais (MC) que ocorrem durante o sono para diagnosticar e predizer as conseqüências, em longo prazo, da asfixia perinatal é contraditório. Este estudo investigou se ratos recém-nascidos (RN) manifestam MC em resposta compensatória à asfixia, e se estas alterações podem ter alguma importância na sua patogênese. Métodos: Oito ratos RN (6-48h de vida) foram submetidos à implantação de pequenos eletrodos para registros da eletromiografia e eletrocardiografia. Os MC e a freqüência cardíaca (FC) foram registrados durante períodos de 30 min: fase controle (F 1 ), fases de asfixia (F 2 ; F 3 ) e fase de recuperação pós-asfixia (F 4 ). A asfixia foi promovida pelo envolvimento completo do animal com uma lâmina de polivinil. Resultados: A FC diminuiu progressivamente durante F 2 e F 3 até a bradicardia. Em F 2 houve grande agitação dos animais e aumento dos períodos de vigília. Em F 3 houve redução significante dos MC de 12,5 ± 0,5 (Md ± SE/2min) para 9,0 ± 0,44 (P<0,05). A freqüência dos MC aumentou em F 4 para 15,0 ± 0,49. Conclusão: Estes dados mostram que ratos RN com asfixia apresentam MC compensatórios durante o sono que podem ajudar no diagnóstico desta afecção e de outros problemas relacionados aos parâmetros do sono. Descritores: Sono. Recém-Nascido. Asfixia. Atividade Motora. Ratos.

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“…This difference in CBF may be attributable to the high arterial CO 2 levels observed in the untreated control group, which might further contribute to the development of brain injury (25). In addition, a higher CBF in the control group might also be explained by a physiological mechanism of blood redistribution toward the cerebral circulation to protect the brain from severe hypoxia (26,27). In the animals in the untreated control group, MABP …”

Section: Discussionmentioning

confidence: 99%

Aerosolized perfluorocarbon improves gas exchange and pulmonary mechanics in preterm lambs with severe respiratory distress syndrome

et al. 2012

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Background: aerosolized perfluorocarbon (PFc) has been proposed as an alternative method of PFc administration; however, the efficacy of aerosolized PFc in a preterm animal model has not yet been demonstrated. Methods: Twelve preterm lambs were randomized to two groups: a perfluorodecalin (PFD) aerosol group (n = 6) receiving 10 ml/kg/h of PFD delivered by an intratracheal inhalation catheter followed by 4 h of mechanical ventilation (MV) or the control group, in which animals (n = 6) were managed for 6 h with MV. Gas exchange, pulmonary mechanics, cardiovascular parameters, and cerebral blood flow (cBF) were measured. results: Both groups developed hypoxia, hypercarbia, and acidosis at baseline. aerosolized PFD improved oxygenation (P < 0.0001) and pulmonary mechanics (P < 0.0001) and changed carbon dioxide values to normal physiological levels, unlike the treatment given to the controls (P < 0.0003). The time course of mean arterial blood pressure and cBF were significantly affected by PFD aerosolization, especially during the first hour of life. cBF gradually decreased during the first hour in the PFD aerosol group and remained stable until the end of the follow-up, whereas cBF remained higher in the control group (P < 0.0028). conclusion: aerosolized PFD improves pulmonary function in preterm lambs and should be further investigated as an alternative mode of PFc administration.

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Cardiovascular responses to hypoxemia and acidemia in fetal lambs

Cited by 760 publications

References 14 publications

Hemodynamic responses of the sheep fetus to vasopressin infusion.

Hemodynamic responses of the sheep fetus to vasopressin infusion.

Compensatory rebound of body movements during sleep, after asphyxia in neonatal rats

Aerosolized perfluorocarbon improves gas exchange and pulmonary mechanics in preterm lambs with severe respiratory distress syndrome

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