Littérature scientifique sur le sujet « Ventilated preterm newborn »
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Articles de revues sur le sujet "Ventilated preterm newborn"
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Smith, Lynne M., Machiko Ikegami, Glenda C. Calvario, James Surdilla et M. Gore Ervin. « Renal responses to angiotensin II receptor blockade in ventilated preterm newborn lambs ». Reproduction, Fertility and Development 11, no 8 (1999) : 419. http://dx.doi.org/10.1071/rd00009.
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Renal and cardiovascular immaturity has been linked with poor outcomes in the premature human newborn. Despite extensive study in the fetus, the contribution of the renin–angiotensin system to renal and cardiovascular function in the premature newborn has not been well characterized. To evaluate the angiotensin II contribution to preterm newborn renal and cardiovascular functions, preterm (120-day) and near-term (136-day) lambs were Caesarean delivered and ventilated. One hour following delivery, animals were randomized to receive angiotensin II receptor-blockade (saralasin; 20 g kg–1 min–1) or saline (CON). Prior to blockade, mean SEM values for urine flow (UFlow), urinary sodium excretion (UNaV), and fractional excretion of sodium (FENa) were similar in all groups. Angiotensin II receptor-blockade decreased Uflow, UNaV and FENa in the 120-day group with no changes in the 136-day animals. No changes in mean arterial pressure, or plasma angiotensin II, aldosterone, and renin activity levels were noted at either gestational age. Conclusions: (1) angiotensin II contributes to the regulation of renal function in 120-day preterm lambs without changing blood pressure and (2) angiotensin II-mediated feedback inhibition of renin release is uncoupled in preterm newborns.
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Berry, LM, M. Ikegami, E. Woods et MG Ervin. « Postnatal renal adaptation in preterm and term lambs ». Reproduction, Fertility and Development 7, no 3 (1995) : 491. http://dx.doi.org/10.1071/rd9950491.
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The present experiments determined if increases in renal reabsorptive capacity during the transition from fetal to neonatal life are gestation dependent. Renal function was studied in chronically-catheterized fetal lambs (133 +/- 1 days; term, 145-150 days). Additionally, renal function was studied in anaesthetized, ventilated, caesarean-delivered preterm lambs (109-139 days gestation) and term lambs (148 days gestation), and in 2-day-old spontaneously-delivered term lambs. Newborns < or = 120 days old received surfactant to facilitate ventilation and maintenance of physiologic blood gases. Two hours after caesarian delivery, urine osmolality, urine flow, glomerular filtration rate (GFR), and fractional sodium excretion (FENa) values were similar for all gestations. Relative to fetal values, caesarean-delivered newborn renal values included lower urine flow rates (0.20 +/- 0.03 v. 0.05 +/- 0.01 mL min-1 kg-1), higher urine osmolalities (118 +/- 15 v. 422 +/- 16 mOsmol kg-1 H2O), and no differences in GFR or FENa. Relative to caesarean-delivered newborns, 2-day newborn renal function included higher values for GFR (0.7 +/- 0.1 v. 3.0 +/- 0.1 mL min-1 kg-1) and urine osmolality (724 +/- 32 mosmol kg-1 H2O), and lower FENa (7.0 +/- 1.5 v. 0.2 +/- 0.02%), and urine flow (0.005 +/- 0.003 mL min-1 kg-1). The 132- and 139-day animals were ventilated for 5 h and 10 h respectively; the only functional change at 10 h was a decrease in FENa (7.0 +/- 1.5 v. 2.8 +/- 0.1%). It is concluded that: (1) relative to fetal animals, renal adaptive responses in anaesthetized, ventilated newborns begin within 2 h following caesarian delivery; (2) initial adaptive responses are not gestation dependent after 109 days; and (3) the combined effects of ventilation and/or anaesthesia delay postnatal renal adaptations for at least 10 h after birth.
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Pryor, Emily J., Marcus J. Kitchen, Michelle K. Croughan, Kelly J. Crossley, Megan J. Wallace, Katie Lee, Arjan B. te Pas, Erin V. McGillick et Stuart B. Hooper. « Improving lung aeration in ventilated newborn preterm rabbits with a partially aerated lung ». Journal of Applied Physiology 129, no 4 (1 octobre 2020) : 891–900. http://dx.doi.org/10.1152/japplphysiol.00426.2020.
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Preterm newborns commonly receive intermittent positive pressure ventilation (iPPV) at birth, but the optimal approach that facilitates uniform lung aeration is unknown, particularly in a partially aerated lung. Using phase contrast X-ray imaging, we showed that combining a long inflation time (1.0 s) with surfactant improved lung mechanics and aeration in the immediate newborn period. The current clinical practice of using short inflation times during iPPV might be suboptimal, and a different approach is needed.
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Allison, Beth J., Domenic A. LaRosa, Samantha K. Barton, Stuart Hooper, Valerie Zahra, Mary Tolcos, Kyra Y. Y. Chan et al. « Dose-dependent exacerbation of ventilation-induced lung injury by erythropoietin in preterm newborn lambs ». Journal of Applied Physiology 126, no 1 (1 janvier 2019) : 44–50. http://dx.doi.org/10.1152/japplphysiol.00800.2018.
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Erythropoietin (EPO) is being trialled in preterm infants to reduce brain injury, but high doses increase lung injury in ventilated preterm lambs. We aimed to determine whether early administration of lower doses of EPO could reduce ventilation-induced lung injury and systemic inflammation in preterm lambs. Ventilation was initiated in anaesthetized preterm lambs [125 ± 1 (SD) days gestation] using an injurious strategy for the first 15 min. Lambs were subsequently ventilated with a protective strategy for a total of 2 h. Lambs were randomized to receive either intravenous saline (Vent; n = 7) or intravenous 300 ( n = 5), 1,000 (EPO1000; n = 5), or 3,000 (EPO3000; n = 5) IU/kg of human recombinant EPO via an umbilical vein. Lung tissue was collected for molecular and histological assessment of inflammation and injury and compared with unventilated control lambs (UVC; n = 8). All ventilated groups had similar blood gas and ventilation parameters, but EPO1000 lambs had a lower fraction of inspired oxygen requirement and lower alveolar–arterial difference in oxygen. Vent and EPO lambs had increased lung interleukin (IL)-1β, IL-6, and IL-8 mRNA, early lung injury genes connective tissue growth factor, early growth response protein 1, and cysteine-rich 61, and liver serum amyloid A3 mRNA compared with UVCs; no difference was observed between Vent and EPO groups. Histological lung injury was increased in Vent and EPO groups compared with UVCs, but EPO3000 lambs had increased lung injury scores compared with VENT only. Early low-doses of EPO do not exacerbate ventilation-induced lung inflammation and injury and do not provide any short-term respiratory benefit. High doses (≥3,000 IU/kg) likely exacerbate lung inflammation and injury in ventilated preterm lambs. NEW & NOTEWORTHY Trials are ongoing to assess the efficacy of erythropoietin (EPO) to provide neuroprotection for preterm infants. However, high doses of EPO increase ventilation-induced lung injury (VILI) in preterm lambs. We investigated whether early lower doses of EPO may reduce VILI. We found that lower doses did not reduce, but did not increase, VILI, while high doses (≥3,000 IU/kg) increase VILI. Therefore, lower doses of EPO should be used in preterm infants, particularly those receiving respiratory support.
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Ueda, T., M. Ikegami et A. H. Jobe. « Developmental changes of sheep surfactant : in vivo function and in vitro subtype conversion ». Journal of Applied Physiology 76, no 6 (1 juin 1994) : 2701–6. http://dx.doi.org/10.1152/jappl.1994.76.6.2701.
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Developmental differences in the intrinsic characteristics of surfactant have not been evaluated. Therefore, heavy-subtype surfactant was recovered from alveolar washes of 132-, 139-, and 148-day preterm lambs, 2- to 3-day-old newborn ventilated lambs, and adult sheep. The density of heavy-subtype surfactant and surfactant protein-A-to-saturated phosphatidylcholine ratios increased significantly with developmental age. In contrast, percent conversion from heavy to light surfactant forms was more rapid for surfactant from preterm animals than for surfactant from mature or adult animals. The function of the heavy-subtype surfactant was tested by treating ventilated 27-day gestational age preterm rabbits. The surfactant from the most immature animals was less effective at improving compliance or maintaining lung volumes on deflation than was surfactant from newborn or adult animals. These results demonstrate intrinsic and functional differences in surfactant from developing compared with mature sheep that correlated with the surfactant protein-A-content. The pattern of changes indicates that the preterm animal is at a disadvantage, because the surfactant is intrinsically abnormal relative to that of the adult.
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Ervin, M. Gore, Steven R. Seidner, M. Michelle Leland, Machiko Ikegami et Alan H. Jobe. « Direct fetal glucocorticoid treatment alters postnatal adaptation in premature newborn baboons ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 274, no 4 (1 avril 1998) : R1169—R1176. http://dx.doi.org/10.1152/ajpregu.1998.274.4.r1169.
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Abnormalities of premature newborn adaptation after preterm birth result in significant perinatal mortality and morbidity. We assessed the effects of short-term (24 h) fetal betamethasone exposure on preterm newborn baboon pulmonary and cardiovascular regulation and renal sodium handling during the first 24 h after birth. Male fetal baboons ( Papio) (124-day gestation, term 185 days) received ultrasound-guided intramuscular injections of saline ( n = 5) or betamethasone (0.5 mg/kg; n = 5). Fetuses were cesarean delivered 24 h later, treated with 100 mg/kg surfactant, and ventilated by adjusting peak inspiratory pressures to maintain[Formula: see text] values of 35–50 mmHg for 24 h. Betamethasone- vs. saline-treated mean ± SE newborn body weights (0.45 ± 0.02 vs. 0.41 ± 0.01 kg) were similar. Although prenatal betamethasone did not affect postnatal lung function ([Formula: see text], arterial/alveolar O2 gradient, or dynamic compliance), plasma hormone (cortisol or thyroxine), or catecholamine levels, mean arterial pressure (25 ± 1 vs. 32 ± 1 mmHg), plasma sodium concentration (132 ± 2 vs. 138 ± 1 meq/l), glomerular filtration rate (0.07 ± 0.02 vs. 0.16 ± 0.02 ml ⋅ min−1 ⋅ kg−1), and renal total sodium reabsorption (1.5 ± 0.5 vs. 16.0 ± 3.0 μeq ⋅ min−1 ⋅ kg−1) values were significantly lower in saline-treated than in betamethasone-treated newborns at 24 h. We conclude that despite the fact that there are no pulmonary and endocrine effects, antenatal glucocorticoid exposure alters premature newborn baboon vascular and renal glomerular function and improves sodium reabsorption after preterm delivery.
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Lakshminrusimha, Satyan, Sylvia F. Gugino, Krishnamurthy Sekar, Stephen Wedgwood, Carmon Koenigsknecht, Jayasree Nair et Bobby Mathew. « Inhaled Nitric Oxide at Birth Reduces Pulmonary Vascular Resistance and Improves Oxygenation in Preterm Lambs ». Children 8, no 5 (11 mai 2021) : 378. http://dx.doi.org/10.3390/children8050378.
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Resuscitation with 21% O2 may not achieve target oxygenation in preterm infants and in neonates with persistent pulmonary hypertension of the newborn (PPHN). Inhaled nitric oxide (iNO) at birth can reduce pulmonary vascular resistance (PVR) and improve PaO2. We studied the effect of iNO on oxygenation and changes in PVR in preterm lambs with and without PPHN during resuscitation and stabilization at birth. Preterm lambs with and without PPHN (induced by antenatal ductal ligation) were delivered at 134 d gestation (term is 147–150 d). Lambs without PPHN were ventilated with 21% O2, titrated O2 to maintain target oxygenation or 21% O2 + iNO (20 ppm) at birth for 30 min. Preterm lambs with PPHN were ventilated with 50% O2, titrated O2 or 50% O2 + iNO. Resuscitation with 21% O2 in preterm lambs and 50%O2 in PPHN lambs did not achieve target oxygenation. Inhaled NO significantly decreased PVR in all lambs and increased PaO2 in preterm lambs ventilated with 21% O2 similar to that achieved by titrated O2 (41 ± 9% at 30 min). Inhaled NO increased PaO2 to 45 ± 13, 45 ± 20 and 76 ± 11 mmHg with 50% O2, titrated O2 up to 100% and 50% O2 + iNO, respectively, in PPHN lambs. We concluded that iNO at birth reduces PVR and FiO2 required to achieve target PaO2.
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Wada, Norihisa, M. Gore Ervin et Machiko Ikegami. « Effect of ventilation style on cardiovascular and renal adaptation in preterm newborn lambs ». American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 275, no 3 (1 septembre 1998) : R836—R843. http://dx.doi.org/10.1152/ajpregu.1998.275.3.r836.
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Renal adaptive responses during the 24 h after delivery in term newborn lambs include marked increases in both glomerular filtration rate (GFR) and sodium reabsorption. This study investigated the effects of ventilation style on cardiovascular, renal, and endocrine adaptations in preterm newborn lambs. Lambs ( n = 62) were delivered by cesarean section at 131 days gestation (term = 150 days), treated with surfactant, and randomized to one of three ventilation strategies: high-frequency oscillation (12 Hz), high rate (50 breaths/min; tidal volume = 8 ml/kg), or low rate (15 breaths/min; tidal volume = 15 ml/kg). Lambs (5 or 6/group) were ventilated for 2, 5, 10, and 24 h to maintain arterial[Formula: see text] between 45 and 50 mmHg. Plasma vasopressin levels decreased to <25 pg/ml by 10 h, and fractional sodium excretion decreased to <1% by 16 h in all groups. However, cardiac output, renal plasma flow, and GFR values did not change over time for any of the groups. The style of ventilation employed had no measurable effects on overall cardiovascular, renal, or endocrine function. We conclude in ventilated preterm lambs that 1) the ventilation style does not affect the time course for postnatal adaptation, 2) adaptive changes in renal tubular sodium reabsorption are evident by 16 h after birth, and 3) changes in preterm newborn renal sodium reabsorption occur in the absence of postnatal changes in renal plasma flow or GFR.
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Sharma, Ravi, et Swapnil Baheti. « Outcome of neonatal ventilation : a prospective and cross-sectional study in tertiary care centre ». International Journal of Contemporary Pediatrics 4, no 5 (23 août 2017) : 1820. http://dx.doi.org/10.18203/2349-3291.ijcp20173793.
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Background: Neonatal mortality accounts for nearly two thirds of infant mortality and half of under 5 mortalities in India. It is possible to increase neonatal survival and improve the quality of life only through prompt and adequate management of critically ill newborn. Mechanical ventilation has become a must to enhance neonatal survival and is an essential component of neonatal intensive care.Methods: Hospital based prospective, cross-sectional study from 1st July 2012 to 30th June 2013. All NICU admitted neonate requiring mechanical ventilation were included. It was a descriptive, cross-sectional study of a prospective data.Results: Indication of mechanical ventilation: Out of 72 neonates studied, majority of preterm were ventilated for RDS - 34 (89.5%) and majority of Full term were ventilated for MAS - 16 (100%) followed by HIE - 8 (88.89%). Out of 38 RDS cases, 30 (79%) were ventilated till 4-7 days duration and 3 (7.9%) required ventilation for >10 days. Out of 16 MAS cases, 10 (62.5%) were ventilated for 4-7 days duration and none required prolonged ventilation. Duration of ventilation is not statistically associated with indication of mechanical ventilation with p=0.301.Conclusions: Mechanical and Pulmonary complications of mechanical ventilation are not statistically significant for outcome of mechanical ventilation but it increases length of NICU stay. Hypotension on ventilator, requirement of more than 3 ionotropes were associated with high mortality.
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Berry, D., A. Jobe et M. Ikegami. « Leakage of macromolecules in ventilated and unventilated segments of preterm lamb lungs ». Journal of Applied Physiology 70, no 1 (1 janvier 1991) : 423–29. http://dx.doi.org/10.1152/jappl.1991.70.1.423.
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The movement of macromolecules into and out of unventilated lung segments was evaluated in prematurely delivered and ventilated lambs. Seven lambs at 130 days gestational age had a bronchial balloon placed at birth before the first breath to obstruct the left lower lobe. Surfactant and 131I-albumin were instilled into the left lower lobe while surfactant and 125I-albumin were instilled into the remaining lung, and 70,000 molecular weight [3H]dextran was given into the vascular space at birth. Twenty-five percent of the lung by weight was not ventilated, and 24% of the total leak of dextran from the vascular space was recovered in the unventilated lungs at 3 h. An epithelial leak of protein from the two lung regions was documented by the loss of 11.4 and 18.4% of the labeled albumins in the nonventilated and ventilated lung regions, the appearance of 4.9 and 7.5% of the airway-instilled albumin in the vascular space from the nonventilated and ventilated lung regions, and the recovery of the labeled albumins in the carcasses of the lambs. The bidirectional flux of macromolecules was larger in the ventilated than in the nonventilated lung regions, indicating that ventilation can increase the leak of protein in the preterm lung. The lung areas that were never exposed to ventilation or oxygen also demonstrated a large bidirectional flux of macromolecules, a finding not present in the fetus, fullterm newborn, or adult. These findings indicate that ventilation is not solely responsible for the increased protein leak found in preterm lungs.(ABSTRACT TRUNCATED AT 250 WORDS)