Predictors of outcome of prematurely born infants with pulmonary interstitial emphysema

Temporal effects of caffeine on intrapulmonary shunt in preterm ventilated infants

OBJECTIVES

We hypothesized that caffeine would be associated with a transient reduction in the right-to-left shunt and VA/Q. We aimed to explore the temporal effects of caffeine on right-to-left shunt, ventilation perfusion ratio (VA/Q) and shift of the oxyhaemoglobin dissociation curve (ODC) in premature ventilated infants.

METHODS

Retrospective cohort study at a tertiary neonatal unit of infants born at less than 31 weeks of gestation that were mechanically ventilated on day three of life. The non-invasive method of the ODC was used to determine the right-to-left shunt, VA/Q and shift before and at 1, 4 and 20 h after a maintenance dose of caffeine citrate.

RESULTS

A total of 21 infants were included with a median (range) gestational age of 27 (23.7-30.7) weeks. The median shunt percentage was significantly reduced, compared to baseline at 1 h (8 (range: 7-9) % vs. 4 (range: 0-6) %, p=0.042) and 4 h post caffeine administration (8 (range: 7-9) % vs. 0 (range: 0-3) %, p=0.042), but the VA/Q and the right shift of the ODC did not differ significantly between these time points. At 20 h, there were no significant differences between these indices compared to baseline values.

CONCLUSIONS

Caffeine led to a transient decrease in intrapulmonary shunt from one to 4 h after administration and this may be due to its diuretic action.

Management of Air Leaks in the Newborn

BACKGROUND

Air leaks, especially pulmonary interstitial emphysema (PIE), are increasingly uncommon respiratory complications of the newborn. Despite PIE having a decreasing incidence, it continues to have a high morbidity and mortality rate. This makes PIE one of the most severe respiratory complications to affect a newborn. Air leaks occur when there is overdistension of the terminal airways or alveoli, which results in air dissecting into extra-alveolar spaces. Recognizing the signs of air leaks is paramount to allow for appropriate diagnosis and treatment of the newborn to improve morbidity and mortality. Treatment modalities range from positioning the newborn in the decubitus position to surgical intervention.

PURPOSE

To summarize current evidence on the pathophysiology, risk factors, diagnosis, treatment, and management of PIE and pneumothorax.

DATA SOURCES

Two databases were systematically reviewed with key words later. Articles in English with date restrictions from 2016 to current were included.

STUDY SELECTION

Inclusion criteria of randomized controlled trials, case studies/reports, and review articles were utilized. Twenty articles, primarily case reports and studies, were reviewed.

DATA EXTRACTION

Guidelines for data abstraction were followed via independent extraction by a single observer.

RESULTS

Qualitative results were utilized to formulate current treatment of air leaks.

IMPLICATIONS FOR PRACTICE

This article provides guidance for frontline neonatal providers on current treatment and management of air leaks in the newborn population.

MSC-EXO and tempol ameliorate bronchopulmonary dysplasia in newborn rats by activating HIF-1α

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a major complication of premature infants and an important cause of morbidity and mortality. This study investigates the effect of the combination of mesenchymal stem cells-derived exosomes (MSC-EXO) and tempol on BPD and analyzes its mechanism.

METHODS

MSC-EXO was extracted by centrifugation and identified by transmission electron microscopy (TEM), nanoparticle tracking analysis, and western blot analysis (WB). Tidal volume (TV), minute ventilation (MV), peak inspiratory flow (PIF), and dynamic pulmonary compliance (Cdyn) of rats were measured by BuxCo pulmonary function experimental platform. Hematoxylin-eosin staining was performed to observe the lung morphology and radical alveolar count (RAC) and mean linear intercept (MLI) were assessed. Immunofluorescence (IF) was conducted to detect the expression of CD31 and α-SMA in pulmonary blood vessels. The kits were used to calculate malondialdehyde (MDA), superoxide dismutase (SOD), and total antioxidant capacity (TAOC) concentration in lung tissue. Enzyme linked immunosorbent assay was applied to detect the levels of IL-1β, IL-17, IL-6, and IFN-γ in bronchoalveolar lavage fluid. In addition, the expressions of HIF-1α, vascular endothelial growth factor (VEGF), p-PI3K, and p-AKT were analyzed by WB and IF.

RESULTS

We successfully extracted and identified MSC-EXO. In BPD rats, TV, MV, PIF, and Cdyn decreased, alveoli were simplified, and the number of interalveoli small vessels, blood vessel density decreased. Moreover, RAC, CD31, TAOC, and SOD decreased, and MLI, α-SMA, MDA, IL-1β, IL-17, IL-6, and IFN-γ increased, which was reversed by the combination of MSC-EXO and tempol treatment after combined treatment. In addition, the expression levels of HIF-1α, VEGF, p-PI3K, and p-AKT were increased after combined treatment.

CONCLUSIONS

Combined treatment could improve lung tissue injury, promote pulmonary vascular remodeling, restore lung function, and inhibit oxidative stress in BPD rats. These effects were achieved through activation of HIF-1α.

Pathophysiology of gas exchange impairment in extreme prematurity: Insights from combining volumetric capnography and measurements of ventilation/perfusion ratio

Background

Infants born extremely preterm often suffer from respiratory disease and are invasively ventilated. We aimed to test the hypothesis that gas exchange in ventilated extremely preterm infants occurs both at the level of the alveoli and via mixing of fresh deadspace gas in the airways.

Methods

We measured the normalised slopes of phase II and phase III of volumetric capnography and related them with non-invasive measurements of ventilation to perfusion ratio (V_A/Q) and right-to-left shunt in ventilated extremely preterm infants studied at one week of life. Cardiac right-to-left shunt was excluded by concurrent echocardiography.

Results

We studied 25 infants (15 male) with a median (range) gestational age of 26.0 (22.9-27.9) weeks and birth weight of 795 (515-1,165) grams. The median (IQR) V_A/Q was 0.52 (0.46-0.56) and shunt was 8 (2-13) %. The median (IQR) normalised slope of phase II was 99.6 (82.7-116.1) mmHg and of phase III was 24.6 (16.9-35.0) mmHg. The V_A/Q was significantly related to the normalised slope of phase III (ρ = -0.573, p = 0.016) but not to the slope of phase II (ρ = 0.045, p = 0.770). The right-to-left shunt was not independently associated with either the slope of phase II or the slope of phase III after adjusting for confounding parameters.

Conclusions

Abnormal gas exchange in ventilated extremely preterm infants was associated with lung disease at the alveolar level. Abnormal gas exchange at the level of the airways was not associated with quantified indices of gas exchange impairment.

Ventilation-to-perfusion relationships and right-to-left shunt during neonatal intensive care in infants with congenital diaphragmatic hernia

BACKGROUND

We aimed to explore the postnatal evolution of ventilation/perfusion ratio (VA/Q) and right-to-left shunt in infants with congenital diaphragmatic hernia (CDH) and whether these indices predicted survival to discharge.

METHODS

Retrospective cohort study at King's College Hospital, London, UK of infants admitted with CDH in 10 years (2011-2021). The non-invasive method of the oxyhaemoglobin dissociation curve was used to determine the VA/Q and shunt in the first 24 h of life, pre-operation, pre-extubation and in the deceased infants, before death.

RESULTS

Eighty-two infants with CDH (71 left-sided) were included with a median (IQR) gestation of 38.1(34.8-39.0) weeks. Fifty-three (65%) survived to discharge from neonatal care. The median (IQR) VA/Q in the first 24 h was lower in the deceased infants [0.09(0.07-0.12)] compared to the ones who survived [0.28(0.19-0.38), p < 0.001]. In the infants who survived, the VA/Q was lower in the first 24 h [0.28 (0.19-0.38)] compared to pre-operation [0.41 (0.3-0.49), p < 0.001] and lower pre-operation compared to pre-extubation [0.48 (0.39-0.55), p = 0.027]. The shunt was not different in infants who survived compared to the infants who did not.

CONCLUSIONS

Ventilation-to-perfusion ratio was lower in infants who died in the neonatal period compared to the ones that survived and improved in surviving infants over the immediate postnatal period.

IMPACT

The non-invasive method of the oxyhaemoglobin dissociation curve was used to determine the ventilation/perfusion ratio VA/Q in infants with congenital diaphragmatic hernia (CDH) in the first 24 h of life, pre-operation, pre-extubation and in the deceased infants, before death. The VA/Q in the first 24 h of life was lower in the infants who did not survive to discharge from neonatal care compared to the ones who survived. In the infants who survived, the VA/Q improved over the immediate postnatal period. The non-invasive calculation of VA/Q can provide valuable information relating to survival to discharge.

Non-invasive assessment of intrapulmonary shunt and ventilation to perfusion ratio in children with hepatopulmonary syndrome before and after liver transplantation

OBJECTIVES

To use the oxyhaemoglobin dissociation curve (ODC) to non-invasively measure the ventilation perfusion ratio (V_A/Q) and right-to-left intrapulmonary vascular shunt before and after liver transplantation (LT) in children with hepatopulmonary syndrome (HPS). To investigate whether the right-to-left shunt derived by ODC correlated with the shunt derived by technetium-99 labelled macroaggregated albumin lung perfusion scan (MAA).

METHODS

A retrospective cohort study at King's College Hospital NHS Foundation Trust, London, UK was performed between 1998 and 2016. The V_A/Q and right-to-left shunt were non-invasively measured pre and post LT. The pre-LT right-to-left intrapulmonary shunt was also measured by MAA. The non-invasively derived pre-LT shunt was correlated with the shunt derived by MAA.

RESULTS

Fifteen children with HPS were studied with a median (IQR) age at LT of 8.8 (6.6-12.9) years. The median (IQR) pre-LT V_A/Q [0.49 (0.42-0.65)] was lower compared to the post-LT V_A/Q [0.61 (IQR 0.54-0.72), p = 0.012]. The median (IQR) pre-LT shunt was 19 (3-24) % which decreased to zero in all but one children post-LT, (p = 0.001). The MAA-derived shunt was significantly positively correlated with the ODC-derived shunt (r = 0.783, p = 0.001). The mean (SD) difference between shunt derived by ODC and shunt derived by MAA was 0.5 (7.2) %.

CONCLUSIONS

Ventilation/perfusion impairment reverses but not completely resolves after liver transplantation in children with hepatopulmonary syndrome. The non-invasive method for estimating intrapulmonary shunting could be used as an alternative to the macroaggregated albumin scan in this population.

Preeclampsia was a risk factor for pulmonary interstitial emphysema in preterm infants born ≤32 weeks of gestational age

AIM

This study determined the prenatal and postnatal risk factors for pulmonary interstitial emphysema (PIE) in preterm infants born at up to 32 weeks of gestational age (GA) and their contribution to severe complications.

METHODS

We studied 179 preterm infants, who had undergone chest X-rays during the first five days of life at Justus Liebig University Giessen, Germany, between 2016 and 2017. Of these, 33 were retrospectively classified as PIE and 146 as non-PIE. The PIE cases were also matched with 33 non-PIE cases by GA and gender. Risk factors were identified by univariate analyses and multivariable logistic regression.

RESULTS

Previously known risk factors for pulmonary interstitial emphysema were confirmed, including GA and birthweight and the associations with adverse outcomes like intraventricular haemorrhage and mortality. We identified preeclampsia and haemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome as additional risk factors for PIE (P = .027), and lung impairment was associated with respiratory distress syndrome (P = .001), higher maximum inspired oxygen (P = .014) and needing surfactant (P = .006).

CONCLUSION

Preeclampsia and HELLP syndrome were identified as possible additional risk factors for PIE in preterm infants. These conditions should be included in future studies, to identify preterm infants at risk of PIE straight after birth.

Unilateral neonatal pulmonary interstitial emphysema managed conservatively: A case report

BACKGROUND

Pulmonary interstitial emphysema (PIE) is a pathological state when air escapes from ruptured alveoli and is trapped along the sheaths surrounding the bronchovascular bundle. PIE is not uncommon in infants who require mechanical ventilation and even less common in infants on noninvasive ventilatory support; however, it is extremely unusual in infants in room air.

CASE PRESENTATION

A 2-week-old male infant developed worsening tachypnea in the special-care nursery. The patient was born at 33 weeks' gestation by induced vaginal delivery due to pre-eclampsia. He required positive pressure ventilation at birth and was admitted to the neonatal intensive care unit on nasal continuous positive airway pressure. On the second day of life, exogenous surfactant was administered via endotracheal tube due to increased oxygen requirement, and, soon after, he was weaned off all respiratory support. After 10 days of stability, he developed tachypnea with diminished air entry on the left side of the chest. Chest radiograph and chest computerized tomography confirmed left-sided unilateral PIE. The patient was treated conservatively with positional therapy alone. Significant clinical and radiographic improvement was noticed within 4 days; almost complete resolution by 10 days and the infant was discharged 23 days later. At follow-up at 7 months, the infant was found to be symptom-free with a normal chest radiograph.

CONCLUSIONS

Traditional management of unilateral PIE generally involves a combination of invasive ventilatory support and positional therapy to break the vicious cycle pathophysiology of PIE. This report focuses on the insidious progression of PIE in nonventilated neonates and describes a nontraditional conservative management strategy for the management of unilateral PIE.

Chronology and Determinants of Respiratory Function Changes Following Administration of Systemic Postnatal Corticosteroids in Extremely Preterm Infants

OBJECTIVE

To describe the effect of systemic corticosteroids administered to treat evolving bronchopulmonary dysplasia on oxygen diffusion and ventilation efficiency.

STUDY DESIGN

This was a retrospective cohort study of ventilated infants who received a 9-day course of dexamethasone in a tertiary neonatal unit. We calculated the transcutaneous oxygen saturation-to-fraction of inspired oxygen (F_iO₂) ratio (SFR), the ventilation perfusion ratio (V_A/Q), and the ventilation efficiency index (VEI) before, during, and after the course of corticosteroids. The response to corticosteroids was calculated as the difference between the F_iO₂ percentage before starting steroids and the lowest F_iO₂ value during the course of steroid treatment.

RESULTS

Seventy infants (38 males) with a median gestational age (GA) of 25.0 weeks (IQR, 24.3-26.0 weeks) and a median birth weight of 0.70 kg (IQR, 0.63-0.82 kg) were studied at a median postnatal age of 39 days (IQR, 29-48 days). The median SFR before treatment was 1.42 (IQR, 1.19-1.72), and the highest SFR was 2.35 (IQR, 1.87-2.83) after 9 days of treatment. The median V_A/Q before treatment was 0.14 (IQR, 0.11-0.18) and was significantly higher at 72 hours after the start of treatment (0.22; IQR, 0.15-0.29; P < .001). The median VEI was 0.06 (IQR, 0.04-0.08) before treatment and was highest, 0.10 (IQR, 0.07-0.13) at 48 hours after starting treatment. The median rate of response to corticosteroids was 28% (IQR, 20%-37%). GA was significantly related to the response to corticosteroids (ρ = 0.283; P = .019).

CONCLUSIONS

Oxygen diffusion continues to improve throughout the entire duration of a 9-day course of systemically administered corticosteroids in ventilated extremely preterm infants. More immature infants are less responsive to corticosteroids.