Lung recruitment at birth does not improve lung function in immature lambs receiving surfactant

Björklund, Lars; Ingimarsson, Jónas; Curstedt, Tore; Larsson, Anders; Robertson, Bengt; Werner, Olof

doi:10.1034/j.1399-6576.2001.450811.x

Cited by 56 publications

(37 citation statements)

References 20 publications

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“…Another possible explanation is that more immature infants have a higher risk of air leaks when exposed to sustained inflations. Five sustained inflations with a duration of 5 s using a tidal volume of 8, 16 and 32 ml/kg affected lung compliance and impaired response to surfactant in preterm lambs, suggesting lung damage secondary to overdistension [29]. The use of sustained inflations with a tidal volume of 16 ml/kg resulted in impaired lung mechanics when applied immediately after birth [30].…”

Section: Discussionmentioning

confidence: 99%

Risk Indicators for Air Leaks in Preterm Infants Exposed to Restrictive Use of Endotracheal Intubation

et al. 2015

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Objectives: To identify perinatal risk indicators for air leaks in preterm infants treated with a policy of restrictive use of endotracheal intubation based on sustained inflations followed by noninvasive ventilation in the delivery room. Methods: Perinatal variables and variables of respiratory support in the delivery room were analyzed retrospectively in a cohort of 297 inborn preterm infants with a gestational age <29 weeks born in 2005-2009 in a tertiary care center with respect to their associations with air leaks. Multivariate logistic regression analysis was performed to analyze independent risk indicators. Results: Gestational age was 26 weeks + 0 days (22+3 to 28+6), birth weight was 790 g (265-1,660) and 270/297 survived (91.0%). A total of 63 (21.2%) developed air leaks, 32 (10.8%) pneumothorax, 44 (14.8%) pulmonary interstitial emphysema, and 1 (0.3%) pneumopericardium. The infants with air leaks had a higher risk of death (p < 0.01) and of intraventricular hemorrhage grade 3/4 (p < 0.05). Air leaks were associated with less use of prenatal steroids (p < 0.01), more frequent use of cardiac compressions (p < 0.01), use of a pressure of 30 cm H₂O for sustained inflations (p < 0.05), and intubation in the delivery room (p < 0.01). After multivariate logistic regression only prenatal steroids (OR 0.41, 0.20-0.85), epinephrine (OR 3.56, 1.55-8.15) and surfactant use (OR 12.03, 3.39-42.72) remained significant. Conclusions: Our approach resulted in a high survival rate but was associated with a substantial rate of air leaks, which were associated with death and severe intraventricular hemorrhage. Prenatal steroids were protective, and epinephrine and surfactant use were significant risk indicators, whereas the use of sustained inflations was not a risk factor.

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Section: Discussionmentioning

confidence: 99%

Risk Indicators for Air Leaks in Preterm Infants Exposed to Restrictive Use of Endotracheal Intubation

et al. 2015

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“…Whether recruitment maneuvers for mechanically ventilated neonates are of clinical benefit is debatable (33). In healthy neonates, recruitment seems to improve lung compliance (17), yet, lung recruitment at birth does not improve the response to surfactant in immature lambs, and may have an adverse effect on lung function and morphology (34).…”

Section: Discussionmentioning

confidence: 99%

Mechanical Ventilation Effect on Surfactant Content, Function, and Lung Compliance in the Newborn Rat

et al. 2004

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Studies of ventilator-associated lung injury in adult experimental animal models have documented that high tidal volume (TV) results in lung injury characterized by impaired compliance and dysfunctional surfactant. Yet, there is evidence that, in neonates, ventilation with a higher than physiologic TV leads to improved lung compliance. The purpose of our study was to evaluate how lung compliance and surfactant was altered by high TV ventilation in the neonate. We utilized a new model (mechanically air-ventilated newborn rats, 4 -8 d old), and used 40 or 10 mL/kg TV strategies. Age-matched nonventilated animals served as controls. In all animals, dynamic compliance progressively increased after initiation of mechanical ventilation and was significantly greater than basal values after 60 min (p Ͻ 0.01). Lung lavage total surfactant with both TV strategies (p Ͻ 0.05) and the large aggregate fraction (only in TV ϭ 40 mL/kg; p Ͻ 0.01) were significantly increased by 60 min of mechanical ventilation, compared with control animals. Ventilation with 40 mL/kg TV for 60 min adversely affected the lung surfactant surface-tension lowering properties (p Ͻ 0.01). After 180 min of ventilation with 40 mL/kg TV, the lung total surfactant content and dynamic compliance values were no longer distinct from the nonventilated animals' values. We conclude that, in the newborn rat, mechanical ventilation with a higher than physiologic TV increases alveolar surfactant content and, over time, alters its biophysical properties, thus promoting an initial but transient improvement in lung compliance. A single stretch of alveolar type II cells causes an increase in cytosolic calcium resulting in stimulation of surfactant secretion for up to 30 min post stretch (1). In adult animals, this mechanism is operative after an increase in spontaneous breathing tidal volume (2, 3), but never demonstrated after short-term mechanical ventilation with a higher than physiologic tidal volume.Isolated adult rat lungs mechanically ventilated with a tidal volume four times higher than physiologic (25 mL/kg) for 1 h showed a decrease in lung compliance (4), which was associated with an increased conversion from LA to SA within the alveolar space (5). These latter changes likely accounted for the reduction in compliance, inasmuch as adequate biophysical activity of surfactant is dependent on a functional LA fraction.The concept that high tidal volumes may have adverse effects has been consistently demonstrated in multiple animal models of adult ventilator-associated lung injury (6 -8). This concept has driven a variety of strategies aimed at reducing tidal stretch, including permissive hypercapnia (9 -11), as well as studies designed to limit pressure and volume ventilatory parameters associated with tidal stretch (12-14). Indeed, in

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“…The method to obtain the PV-loops has been reported previously. 8 In short, the lungs were slowly (65 ml/sec) inflated to an airway pressure of 40 cmH 2 O. The pressure was kept constant for 5 sec, and the lungs were then passively deflated against a resistance.…”

Section: Methodsmentioning

confidence: 99%

Inflation lung mechanics deteriorates markedly after saline instillation and open endotracheal suctioning in mechanically ventilated healthy piglets

Cunha-Goncalves

Perez-de-Sa

Ingimarsson

et al. 2006

Pediatric Pulmonology

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Summary. Introduction Non-bronchoscopic bronchoalveolar lavage is an alternative to diagnostic bronchoscopy in pediatric patients, as fiberoptic bronchoscopes with aspiration channels are too large for small infants. There are many variations of the method in clinical practice, and saline instillation followed by open endotracheal suctioning is still commonly used. Lung function can deteriorate with these procedures, and we have investigated the effects on lung mechanics and oxygenation in healthy piglets. Methods The lungs of anesthetized and mechanically ventilated piglets were recruited with CPAP 35 cmH 2 O. Thereafter we instilled 5 ml of saline into the endotracheal tube, followed by three breaths from the ventilator. Saline was retrieved through a suction catheter wedged far distally in the airway. The procedure was followed by a new recruitment maneuver. Complete inspiratory/expiratory pressure-volume loops (PV-loops) were obtained just before and 5 min after saline instillation. Arterial blood gases were collected at equivalent times in 14 similar piglets submitted to exactly the same procedure. Results The inspiratory limb of the PV-loops changed markedly, as the lower inflection point was displaced towards higher pressures (P ¼ 0.004), and hysteresis measured at 15 and 30 cmH 2 O increased (P ¼ 0.004 and P ¼ 0.012, respectively). Although PaO 2 decreased significantly (P ¼ 0.001), values after saline instillation/ suctioning were still in the high normal range, that is, 22.2 AE 2.6 kPa. Conclusions Opening pressures of the lungs increase markedly after saline instillation/suctioning in healthy piglets. In this situation, adequate recruitment maneuvers and PEEP might prevent lung collapse and deteriorations in arterial oxygenation.

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Lung recruitment at birth does not improve lung function in immature lambs receiving surfactant

Abstract: Lung recruitment at birth does not improve the response to surfactant in immature lambs, but may instead have an adverse effect on lung function and morphology.

Cited by 56 publications

References 20 publications

Risk Indicators for Air Leaks in Preterm Infants Exposed to Restrictive Use of Endotracheal Intubation

Risk Indicators for Air Leaks in Preterm Infants Exposed to Restrictive Use of Endotracheal Intubation

Mechanical Ventilation Effect on Surfactant Content, Function, and Lung Compliance in the Newborn Rat

Inflation lung mechanics deteriorates markedly after saline instillation and open endotracheal suctioning in mechanically ventilated healthy piglets

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