scholarly journals Effectiveness of individualized lung recruitment strategies at birth: an experimental study in preterm lambs

2017 ◽  
Vol 312 (1) ◽  
pp. L32-L41 ◽  
Author(s):  
David G. Tingay ◽  
Anushi Rajapaksa ◽  
Emanuela Zannin ◽  
Prue M. Pereira-Fantini ◽  
Raffaele L. Dellaca ◽  
...  
Keyword(s):  
Lung Injury ◽  
Fetal Lung ◽  
Lung Mechanics ◽  
Impedance Tomography ◽  
Antenatal Steroids ◽  
Sustained Inflation ◽  
Volume Response ◽  
Distal Lung ◽  
Study Completion ◽  
Lung Liquid

Respiratory transition at birth involves rapidly clearing fetal lung liquid and preventing efflux back into the lung while aeration is established. We have developed a sustained inflation (SIOPT) individualized to volume response and a dynamic tidal positive end-expiratory pressure (PEEP) (open lung volume, OLV) strategy that both enhance this process. We aimed to compare the effect of each with a group managed with PEEP of 8 cmH2O and no recruitment maneuver (No-RM), on gas exchange, lung mechanics, spatiotemporal aeration, and lung injury in 127 ± 1 day preterm lambs. Forty-eight fetal-instrumented lambs exposed to antenatal steroids were ventilated for 60 min after application of the allocated strategy. Spatiotemporal aeration and lung mechanics were measured with electrical impedance tomography and forced-oscillation, respectively. At study completion, molecular and histological markers of lung injury were analyzed. Mean (SD) aeration at the end of the SIOPT and OLV groups was 32 (22) and 38 (15) ml/kg, compared with 17 (10) ml/kg (180 s) in the No-RM ( P = 0.024, 1-way ANOVA). This translated into better oxygenation at 60 min ( P = 0.047; 2-way ANOVA) resulting from better distal lung tissue aeration in SIOPT and OLV. There was no difference in lung injury. Neither SIOPT nor OLV achieved homogeneous aeration. Histological injury and mRNA biomarker upregulation were more likely in the regions with better initial aeration, suggesting volutrauma. Tidal ventilation or an SI achieves similar aeration if optimized, suggesting that preventing fluid efflux after lung liquid clearance is at least as important as fluid clearance during the initial inflation at birth.

scholarly journals An individualized approach to sustained inflation duration at birth improves outcomes in newborn preterm lambs

2015 ◽  
Vol 309 (10) ◽  
pp. L1138-L1149 ◽  
Author(s):  
David G. Tingay ◽  
Anna Lavizzari ◽  
Cornelis E. E. Zonneveld ◽  
Anushi Rajapaksa ◽  
Emanuela Zannin ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Lung Injury ◽  
Positive Pressure Ventilation ◽  
Lung Mechanics ◽  
Positive Pressure ◽  
Impedance Tomography ◽  
Tidal Ventilation ◽  
Sustained Inflation ◽  
Volume Response ◽  
The Impact

A sustained first inflation (SI) at birth may aid lung liquid clearance and aeration, but the impact of SI duration relative to the volume-response of the lung is poorly understood. We compared three SI strategies: 1) variable duration defined by attaining volume equilibrium using real-time electrical impedance tomography (EIT; SIplat); 2) 30 s beyond equilibrium (SIlong); 3) short 30-s SI (SI30); and 4) positive pressure ventilation without SI (no-SI) on spatiotemporal aeration and ventilation (EIT), gas exchange, lung mechanics, and regional early markers of injury in preterm lambs. Fifty-nine fetal-instrumented lambs were ventilated for 60 min after applying the allocated first inflation strategy. At study completion molecular and histological markers of lung injury were analyzed. The time to SI volume equilibrium, and resultant volume, were highly variable; mean (SD) 55 (34) s, coefficient of variability 59%. SIplat and SIlong resulted in better lung mechanics, gas exchange and lower ventilator settings than both no-SI and SI30. At 60 min, alveolar-arterial difference in oxygen was a mean (95% confidence interval) 130 (13, 249) higher in SI30 vs. SIlong group (two-way ANOVA). These differences were due to better spatiotemporal aeration and tidal ventilation, although all groups showed redistribution of aeration towards the nondependent lung by 60 min. Histological lung injury scores mirrored spatiotemporal change in aeration and were greatest in SI30 group ( P < 0.01, Kruskal-Wallis test). An individualized volume-response approach to SI was effective in optimizing aeration, homogeneous tidal ventilation, and respiratory outcomes, while an inadequate SI duration had no benefit over positive pressure ventilation alone.

scholarly journals Pressure-limited sustained inflation vs. gradual tidal inflations for resuscitation in preterm lambs

2015 ◽  
Vol 118 (7) ◽  
pp. 890-897 ◽  
Author(s):  
David G. Tingay ◽  
Graeme R. Polglase ◽  
Risha Bhatia ◽  
Clare A. Berry ◽  
Robert J. Kopotic ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Lung Injury ◽  
Gradual Increase ◽  
Lung Mechanics ◽  
Arterial Oxygen ◽  
Volume Distribution ◽  
Dependent Lung ◽  
Impedance Tomography ◽  
Sustained Inflation ◽  
Mrna Markers

Support of the mechanically complex preterm lung needs to facilitate aeration while avoiding ventilation heterogeneities: whether to achieve this gradually or quickly remains unclear. We compared the effect of gradual vs. constant tidal inflations and a pressure-limited sustained inflation (SI) at birth on gas exchange, lung mechanics, gravity-dependent lung volume distribution, and lung injury in 131-day gestation preterm lambs. Lambs were resuscitated with either 1) a 20-s, 40-cmH2O pressure-limited SI (PressSI), 2) a gradual increase in tidal volume (Vt) over 5-min from 3 ml/kg to 7 ml/kg (IncrVt), or 3) 7 ml/kg Vt from birth. All lambs were subsequently ventilated for 15 min with 7 ml/kg Vt with the same end-expiratory pressure. Lung mechanics, gas exchange and spatial distribution of end-expiratory volume (EEV), and tidal ventilation (electrical impedance tomography) were recorded regularly. At 15 min, early mRNA tissue markers of lung injury were assessed. The IncrVt group resulted in greater tissue hysteresivity at 5 min ( P = 0.017; two-way ANOVA), higher alveolar-arterial oxygen difference from 10 min ( P < 0.01), and least uniform gravity-dependent distribution of EEV. There were no other differences in lung mechanics between groups, and the PressSI and 7 ml/kg Vt groups behaved similarly throughout. EEV was more uniformly distributed, but Vt least so, in the PressSI group. There were no differences in mRNA markers of lung injury. A gradual increase in Vt from birth resulted in less recruitment of the gravity-dependent lung with worse oxygenation. There was no benefit of a SI at birth over mechanical ventilation with 7 ml/kg Vt.

scholarly journals Sustained inflation at birth did not protect preterm fetal sheep from lung injury

2013 ◽  
Vol 305 (6) ◽  
pp. L446-L453 ◽  
Author(s):  
Noah H. Hillman ◽  
Matthew W. Kemp ◽  
Peter B. Noble ◽  
Suhas G. Kallapur ◽  
Alan H. Jobe
Keyword(s):  
Mechanical Ventilation ◽  
Lung Injury ◽  
Acute Phase ◽  
Acute Phase Proteins ◽  
Fetal Lung ◽  
Fetal Sheep ◽  
Lung Fluid ◽  
Sustained Inflation ◽  
Proinflammatory Responses ◽  
Residual Capacity

Sustained lung inflations (SI) at birth may recruit functional residual capacity (FRC). Clinically, SI increase oxygenation and decrease need for intubation in preterm infants. We tested whether a SI to recruit FRC would decrease lung injury from subsequent ventilation of fetal, preterm lambs. The preterm fetus (128 ± 1 day gestation) was exteriorized from the uterus, a tracheostomy was performed, and fetal lung fluid was removed. While maintaining placental circulation, fetuses were randomized to one of four 15-min interventions: 1) positive end-expiratory pressure (PEEP) 8 cmH2O ( n = 4), 2) 20 s SI to 50 cmH2O then PEEP 8 cmH2O ( n = 10), 3) mechanical ventilation at tidal volume (VT) 7 ml/kg ( n = 13), or 4) 20 s SI then ventilation at VT 7 ml/kg ( n = 13). Lambs were ventilated with 95% N2/5% CO2 and PEEP 8 cmH2O. Volume recruitment was measured during SI, and fetal tissues were collected after an additional 30 min on placental support. SI achieved a mean FRC recruitment of 15 ml/kg (range 8–27). Fifty percent of final FRC was achieved by 2 s, 65% by 5 s, and 90% by 15 s, demonstrating prolonged SI times are needed to recruit FRC. SI alone released acute-phase proteins into the fetal lung fluid and increased mRNA expression of proinflammatory cytokines and acute-phase response genes in the lung. Mechanical ventilation further increased all markers of lung injury. SI before ventilation, regardless of the volume of FRC recruited, did not alter the acute-phase and proinflammatory responses to mechanical ventilation at birth.

scholarly journals Respiratory mechanics during initial lung aeration at birth in the preterm lamb

2020 ◽  
Vol 318 (3) ◽  
pp. L525-L532 ◽  
Author(s):  
Chiara Veneroni ◽  
David G. Tingay ◽  
Karen E. McCall ◽  
Prue M. Pereira-Fantini ◽  
Elizabeth J. Perkins ◽  
...  
Keyword(s):  
Lung Volume ◽  
Lung Mechanics ◽  
Forced Oscillation Technique ◽  
Volume Changes ◽  
Impedance Tomography ◽  
Lung Aeration ◽  
Sustained Inflation ◽  
Airway Opening ◽  
Respiratory System Resistance ◽  
Direct Reflection

Despite recent insights into the dynamic processes during lung aeration at birth, several aspects remain poorly understood. We aimed to characterize changes in lung mechanics during the first inflation at birth and their relationship to changes in lung volume. Intubated preterm lambs (gestational age, 124–127 days; n = 17) were studied at birth. Lung volume changes were measured by electrical impedance tomography (VL EIT). Respiratory system resistance (R5) and oscillatory compliance (Cx5) were monitored with the forced oscillation technique at 5 Hz. Lambs received 3–7 s of 8 cmH2O of continuous distending pressure (CDP) before delivery of a sustained inflation (SI) of 40 cmH2O. The SI was then applied until either Cx5 or the VL EIT or the airway opening volume was stable. CDP was resumed for 3–7 s before commencement of mechanical ventilation. The exponential increases with time of Cx5 and VL EIT from commencement of the SI were characterized by estimating their time constants (τCx5 and τVL EIT, respectively). During SI, a fast decrease in R5 and an exponential increase in Cx5 and VL EIT were observed. Cx5 and VL EIT provided comparable information on the dynamics of lung aeration in all lambs, with τCx5 and τVL EIT being highly linearly correlated ( r2 = 0.87, P < 0.001). Cx5 and VL EIT decreased immediately after SI. Despite the standardization of the animal model, changes in Cx5 and R5 both during and after SI were highly variable. Lung aeration at birth is characterized by a fast reduction in resistance and a slower increase in oscillatory compliance, the latter being a direct reflection of the amount of lung aeration.

Surfactant before the first inflation at birth improves spatial distribution of ventilation and reduces lung injury in preterm lambs

2014 ◽  
Vol 116 (3) ◽  
pp. 251-258 ◽  
Author(s):  
David G. Tingay ◽  
Megan J. Wallace ◽  
Risha Bhatia ◽  
Georg M. Schmölzer ◽  
Valerie A. Zahra ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Spatial Distribution ◽  
Lung Injury ◽  
Carbon Dioxide Removal ◽  
Lung Mechanics ◽  
Positive Pressure ◽  
Mrna Levels ◽  
Left Hemithorax ◽  
Respiratory Inductive Plethysmography ◽  
Sustained Inflation

The interrelationship between the role of surfactant and a sustained inflation (SI) to aid ex utero transition of the preterm lung is unknown. We compared the effect of surfactant administered before and after an initial SI on gas exchange, lung mechanics, spatial distribution of ventilation, and lung injury in preterm lambs. Gestational-age lambs (127 days; 9 per group) received 100 mg/kg of a surfactant (Curosurf) either prior (Surf+SI) or 10 min after birth (SI+Surf). At birth, a 20-s, 35 cmH2O SI was applied, followed by 70 min of positive pressure ventilation. Oxygenation, carbon dioxide removal, respiratory system compliance, end-expiratory thoracic volume (via respiratory inductive plethysmography), and distribution of end-expiratory volume and ventilation (via electrical impedance tomography) were measured throughout. Early markers of lung injury were analyzed using quantitative RT-PCR. During the first 15 min, oxygenation, carbon dioxide removal, and compliance were better in the Surf+SI group (all P < 0.05). End-expiratory volume on completion of the sustained inflation was higher in the Surf+SI group than the SI+Surf group; 11 ± 1 ml/kg vs. 7 ± 1 ml/kg (mean ± SE) ( P = 0.043; t-test), but was not different at later time points. Although neither achieved homogenous aeration, spatial ventilation was more uniform in the Surf+SI group throughout; 50.1 ± 10.9% of total ventilation in the left hemithorax at 70 min vs. 42.6 ± 11.1% in the SI+Surf group. Surf+SI resulted in lower mRNA levels of CYR61 and EGR1 compared with SI+Surf ( P < 0.001, one-way ANOVA). Surfactant status of the fetal preterm lung at birth influences the mechanical and injury response to a sustained inflation and ventilation by changing surface tension of the air/fluid interface.

scholarly journals Effect of pressure-controlled ventilation-volume guaranteed mode combined with individualized positive end-expiratory pressure on respiratory mechanics, oxygenation and lung injury in patients undergoing laparoscopic surgery in Trendelenburg position

2021 ◽  
Author(s):  
Jianli Li ◽  
Saixian Ma ◽  
Xiujie Chang ◽  
Songxu Ju ◽  
Meng Zhang ◽  
...  
Keyword(s):  
Laparoscopic Surgery ◽  
Lung Injury ◽  
Respiratory Mechanics ◽  
Lung Mechanics ◽  
Trial Registry ◽  
Positive End Expiratory Pressure ◽  
Clinical Trial Registry ◽  
Trendelenburg Position ◽  
Pressure Controlled Ventilation ◽  
Pressure Controlled

AbstractThe study aimed to investigate the efficacy of PCV-VG combined with individual PEEP during laparoscopic surgery in the Trendelenburg position. 120 patients were randomly divided into four groups: VF group (VCV plus 5cmH2O PEEP), PF group (PCV-VG plus 5cmH2O PEEP), VI group (VCV plus individual PEEP), and PI group (PCV-VG plus individual PEEP). Pmean, Ppeak, Cdyn, PaO2/FiO2, VD/VT, A-aDO2 and Qs/Qt were recorded at T1 (15 min after the induction of anesthesia), T2 (60 min after pneumoperitoneum), and T3 (5 min at the end of anesthesia). The CC16 and IL-6 were measured at T1 and T3. Our results showed that the Pmean was increased in VI and PI group, and the Ppeak was lower in PI group at T2. At T2 and T3, the Cdyn of PI group was higher than that in other groups, and PaO2/FiO2 was increased in PI group compared with VF and VI group. At T2 and T3, A-aDO2 of PI and PF group was reduced than that in other groups. The Qs/Qt was decreased in PI group compared with VF and VI group at T2 and T3. At T2, VD/VT in PI group was decreased than other groups. At T3, the concentration of CC16 in PI group was lower compared with other groups, and IL-6 level of PI group was decreased than that in VF and VI group. In conclusion, the patients who underwent laparoscopic surgery, PCV-VG combined with individual PEEP produced favorable lung mechanics and oxygenation, and thus reducing inflammatory response and lung injury.Clinical Trial registry: chictr.org. identifier: ChiCTR-2100044928

The critical concentration of surfactant in fetal lung liquid at birth

1990 ◽  
Vol 80 (2-3) ◽  
pp. 181-192 ◽  
Author(s):  
Tsutomu Kobayashi ◽  
Akemi Shido ◽  
Keiko Nitta ◽  
Sachiko Inui ◽  
Masaya Ganzuka ◽  
...  
Keyword(s):  
Critical Concentration ◽  
Fetal Lung ◽  
Lung Liquid

Lung mechanics are both dose and tidal volume dependant in LPS-induced lung injury

2009 ◽  
Vol 167 (3) ◽  
pp. 333-340 ◽  
Author(s):  
Dani-Louise Dixon ◽  
Hilde R. De Smet ◽  
Andrew D. Bersten
Keyword(s):  
Lung Injury ◽  
Tidal Volume ◽  
Lung Mechanics

Amiloride blocks the inhibition of fetal lung liquid secretion caused by AVP but not by asphyxia

1993 ◽  
Vol 74 (1) ◽  
pp. 111-115 ◽  
Author(s):  
S. B. Hooper ◽  
M. J. Wallace ◽  
R. Harding
Keyword(s):  
Control Period ◽  
Fetal Lung ◽  
Inhibitory Effect ◽  
Luminal Surface ◽  
Na Channels ◽  
Inhibitory Effects ◽  
Fetal Sheep ◽  
Pulmonary Epithelial Cells ◽  
Lung Liquid ◽  
Secretion Rates

We have examined whether the activation of Na+ channels, located on the luminal surface of pulmonary epithelial cells, mediates the inhibitory effects of both arginine vasopressin (AVP) and moderate asphyxia on fetal lung liquid secretion. Lung liquid secretion rates were measured in chronically catheterized fetal sheep during AVP infusions and during periods of asphyxia with and without an Na+ transport blocker (amiloride; 10(-4) M) present in lung liquid. Lung liquid secretion rates were also measured during epinephrine infusions with amiloride present in lung liquid. These secretion rates were compared with measurements made during a preceding control period. Both asphyxia and an infusion of AVP significantly reduced the rate of secretion of fetal lung liquid from 8.4 +/- 1.5 and 18.0 +/- 3.7 to 3.6 +/- 1.0 (P < 0.01) and 5.5 +/- 2.1 ml/h (P < 0.01), respectively. The addition of amiloride to lung liquid did not reverse the inhibitory effects of asphyxia on lung liquid secretion (8.6 +/- 0.8 vs. 0.7 +/- 0.4 ml/h) but did block the inhibitory effects of both epinephrine (14.8 +/- 4.4 vs. 13.8 +/- 3.1 ml/h) and AVP (18.0 +/- 3.7 vs. 19.5 +/- 5.0 ml/h). The addition of amiloride to lung liquid during fetal normoxia did not significantly affect fetal lung liquid secretion rates (8.2 +/- 1.1 vs. 7.4 +/- 0.7 ml/h). We conclude that the inhibitory effect of AVP on fetal lung liquid secretion, like that of epinephrine, involves the activation of luminal surface Na+ channels, whereas the inhibitory effect of asphyxia does not.

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