Effect of different ventilation methods combined with pulmonary surfactant on neonatal acute respiratory distress syndrome

BACKGROUND Acute respiratory distress syndrome precipitates is widespread pulmonary injury in impacted individuals,the neonatal respiratory distress syndrome(NRDS),primarily observed in preterm infants,represents a prevalent critical condition in neonatal clinical settings.AIM To investigate the clinical efficacy of various ventilation strategies combined with pulmonary surfactant(PS)therapy in the treatment of NRDS.METHODS A total of 20 neonates diagnosed with respiratory distress syndrome,admitted between May 2021 and June 2022,were randomly assigned to either a research group or a control group.Neonates in the research group received treatment involving high-frequency oscillatory ventilation(HFOV)in conjunction with PS.In contrast,neonates in the control group were administered either controlled mechanical ventilation or synchronous intermittent mandatory ventilation,combined with PS.Arterial blood samples from the neonates in both groups were collected before treatment,as well as 6 h,12 h,24 h,and 48 h post-treatment.These samples underwent blood gas analysis,with measurements taken for pH value,partial pressures of oxygen(O_(2))and carbon dioxide.Concurrently,data was collected on the duration of ventilator use,length of hospitalization time,O_(2) treatment time,treatment outcomes,and complications of the ventilator.RESULTS From 6-48 h post-treatment,both groups demonstrated significant improvements in arterial blood pH and oxygen partial pressure,along with a significant decrease in carbon dioxide partial pressure compared to pre-treatment values(P<0.05).Although these changes progressed over time,there were no significant differences between the two groups(P>0.05).However,the research group had significantly lower X-ray scores,shorter hospitalization time,and less time on O_(2) therapy compared to the control group(P<0.05).Mortality rates were similar between the two groups(P>0.05),but the research group had a significantly lower incidence of complications(P<0.05).CONCLUSION The integration of HFOV combine with PS has proven to effectively expedite the treatment duration,decrease the occurrence of complications,and secure the therapeutic efficacy in managing NRDS.

Expression of Peroxiredoxins and Pulmonary Surfactant Protein A Induced by Silica in Rat Lung Tissue

Silicosis is one of the most serious occupational diseases in China and dates back to centuries ago. In this study, we successfully established a rat model of silicosis by intratracheal silica injection for 28 days and determined hydroxyproline levels to evaluate collagen metabolism in lung homogenates. Oxidative stress status was evaluated by detecting catalase and glutathione peroxidase activities.

Morphofunctional Characteristics of Pulmonary Surfactant System and Its Effect on Immune Cells in Influenza A (H1N1) Pathogenesis

There is an annual increase of influenza-related SARI cases in winter months. Despite the high relevance of this problem, influenza pathogenesis and the role of surfactant system and its SP-A (surfactant protein A) enzyme in antiviral defense remain poorly understood. SP-A activates macrophage M1 polarization and triggers an antiviral response due to the activation of T-cells and dendritic cells. Therefore, surfactant system is an important element of infection protection and a promising therapeutic target.

Study on Pulmonary Surfactant of Sudden Death of Infant

Objective To find the pathogenesis of sudden infant death syndrome (SIDS) from changes of pulmonary surfactant. Methods By means of thin layer chromatography technique, surfactant in whole lung specimens of 10 infants with SIDS and 10 control infants without SIDS (dead of nonrespiratory diseases) were examined qualitatively and quantitatively. Results Eleven components in pulmonary surfactant were examined qualitatively, including lysophosphatidylcholine, sphingomyelin, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidic acid, cholesterol and neutral lipids. Quantitative examination showed that the amount of surfactant of whole lung specimens in sudden death group [(8.9±1.0) mg/g wet lung weight] was significantly less than that in control group [(12.6±1.4) mg/g wet lung weight, P<0.01]. Qualitative variance showed that the percentages of phosphatidylcholine (49.4%±2.0%) and phosphatidylglycerol (2.6%±0.7%) decreased markedly in sudden death group compared with those in control group (61.5%±3.0% and 4.3%±1.5%, P<0.01). Conclusion Before death there is serious defect on metabolism of pulmonary surfactant in sudden death infants, with the amount decreasing and the ratio of its components being disturbed, which is one of the important pathogenies of SIDS.

Effects of continuous tracheal gas insufflation during pressure limited ventilation on pulmonary surfactant in rabbits with acute lung injury

Background Pulmonary surfactant dysfunction may contribute to the development of ventilator induced lung injury （VILI）. Tracheal gas insuffiation （TGI） is a technique in which fresh gas is introduced into the trachea and augment ventilation by reducing the dead space of ventilatory system, reducing ventilatory pressures and tidal volume （VT） while maintaining constant partial arterial CO2 pressure （PaCO2）. We hypothesised that TGI limited peak inspiratory pressure （PIP） and VT and would minimize conventional mechanical ventilation （CMV） induced pulmonary surfactant dysfunction and thereby attenuate VILI in rabbits with acute lung injury （ALI）. Methods ALI was induced by intratracheal administration of lipopolysaccharide in anaesthetized, ventilated healthy adult rabbits randomly assigned to continuous TGI at 0.5 L/min （TGI group） or CMV group （n=8 for each group）, and subsequently ventilated with limited PIP and VT to maintain PaCO2 within 35 to 45 mmHg for 4 hours. Physiological dead space to VT ratio （VD/VT）, dynamic respiratory compliance （Cdyn） and partial arterial O2 pressure （PaO2） were monitored. After ventilation, lungs were analysed for total phospholipids （TPL）, total proteins （TP）, pulmonary surfactant small to large aggregates ratio （SA/LA） in bronchoalveolar lavage fluid （BALF） and for determination of alveolar volume density （Vv）, myeloperoxidase and interleukin （IL）-8. Results TGI resulted in significant （P〈0.05 or P〈0.01） decrease in PIP [（22.4±1.8） cmH20 vs （29.5±1.1） cmH2O], VT [（6.9±1.3） ml/kg vs （9.8±1.11） ml/kg], VD/VT [（32±5）% vs （46±2）%], TP [（109±22） mg/kg vs （187±25） mg/kg], SA/LA （2.5±0.4 vs 5.4±0.7）, myeloperoxidase [（6.2±0.5） U/g tissue vs （12.3±0.8） U/g tissue] and IL-8 [（987±106） ng/g tissue vs （24±3） mN/m] of BALF, and significant （P〈0.05） increase in Cdyn [（0.47±0.02） ml·cmH2O^-1·kg^-1 vs （0.31±0.02） ml·cmH2O^-1·kg^-1], PaO2 [（175±24） mmHg vs （135±26） mmHg], TPL/TP （52±8 vs 33±11） and Vv （0.65±0.05 vs 0.44±0.07） as compared with CMV. Conclusions In this animal model of ALI, TGI decreased ventilatory requirements （PIP, VT and VD/VT）, resulted in more favourable alveolar pulmonary surfactant composition and function and less severity of lung injury than CMV. TGI in combination with pressure limited ventilation may be a lung protective strategy for ALI.

Prophylaxis of neonatal respiratory distress syndrome by intra-amniotic administration of pulmonary surfactant

Background Neonatal respiratory distress syndrome (NRDS) is caused by a deficiency in pulmonary surfactant (PS) and is one of the main reasons of neonatal mortality. This study was conducted to evaluate the efficacy and safety of intra-amniotic administration of pulmonary surfactant for prophylaxis of NRDS. Methods Forty-five pregnant women who were due for preterm delivery and whose fetuses’ lungs proved immature were divided into two groups. Fifteen women (study group) were administered one dose of pulmonary surfactant injected into the amniotic cavity and delivered within several hours. Nothing was injected into the amniotic cavity of 30 women of the control group. The proportion of neonatal asphyxia,NRDS,mortality and the time in hospital were analyzed to determine if there was any difference between the two groups. Results There was no significant difference between the two groups for neonatal asphyxia. Foam tests showed that higher proportion of neonates in the study group than in the control group (56.3% vs 13.3%, P <0.05) had lung maturity. A greater number of control neonates (11/30,32.3%) had NRDS,compared with the neonates given PS via the amniotic cavity before delivery (1/16,6.3%, P <0.05). The neonates in the study group spent nearly 10 days less in hospital than the control group [(32.4±7.6) days vs (42.0±15.7) days,P <0.05],but the difference in mortality between the two groups was not statistically significant. Conclusions Intra-amniotic administration of pulmonary surfactant can significantly reduce the proportion of NRDS and the time in hospital of preterm neonates. Whether this method can reduce the mortality of preterm neonates needs to be evaluated further. Intra-amniotic administration of pulmonary surfactant provides an additional effectual means for NRDS prophylaxis.

Mesoporous carbon nanomaterials induced pulmonary surfactant inhibition,cytotoxicity,inflammation and lung fibrosis

Environmental exposure and health risk upon engineered nanomaterials are increasingly concerned. The family of mesoporous carbon nanomaterials（MCNs） is a rising star in nanotechnology for multidisciplinary research with versatile applications in electronics,energy and gas storage, and biomedicine. Meanwhile, there is mounting concern on their environmental health risks due to the growing production and usage of MCNs. The lung is the primary site for particle invasion under environmental exposure to nanomaterials. Here, we studied the comprehensive toxicological profile of MCNs in the lung under the scenario of moderate environmental exposure. It was found that at a low concentration of 10 μg/mL MCNs induced biophysical inhibition of natural pulmonary surfactant. Moreover, MCNs at similar concentrations reduced viability of J774 A.1 macrophages and lung epithelial A549 cells.Incubating with nature pulmonary surfactant effectively reduced the cytotoxicity of MCNs.Regarding the pro-inflammatory responses, MCNs activated macrophages in vitro, and stimulated lung inflammation in mice after inhalation exposure, associated with lung fibrosis.Moreover, we found that the size of MCNs played a significant role in regulating cytotoxicity and pro-inflammatory potential of this nanomaterial. In general, larger MCNs induced more pronounced cytotoxic and pro-inflammatory effects than their smaller counterparts. Our results provided valuable information on the toxicological profile and environmental health risks of MCNs, and suggested that fine-tuning the size of MCNs could be a practical precautionary design strategy to increase safety and biocompatibility of this nanomaterial.

Effects of Different Surfactant Administrations on Cerebral Autoregulation in Preterm Infants with Respiratory Distress Syndrome

To treat respiratory distress syndrome,surfactant is currently delivered via less invasive surfactant administration（LISA） or INtubation SURfactant Extubation（INSURE）.The aim of this study was to compare the effect of the two delivery methods of surfactant on cerebral autoregulation.Near infrared spectroscopy monitoring was carried out to detect cerebral oxygen saturation（Sc O2）,and the mean arterial blood pressure（MABP） was simultaneously recorded.Of 44 preterm infants included,the surfactant was administrated to 22 via LISA and 22 via INSURE.The clinical characteristics,treatments and outcomes of the infants showed no significant differences between the two groups.The correlation coefficient of Sc O2 and MABP（rSc O2-MABP） 5 min before administration was similar in the two groups.During surfactant administration,rSc O2-MABP increased in both groups（0.44±0.10 to 0.54±0.12 in LISA,0.45±0.11 to 0.69±0.09 in INSURE）.In the first and second 5 min after instillation,rSc O2-MABP was not significantly different from baseline in the LISA group,but increased in the first 5 min after instillation（0.59±0.13,P=0.000 compared with the baseline in the same group） and recovered in the second 5 min after instillation（0.48±0.10,P=0.321） in the INSURE group.There were significant differences in the change rates of rSc O2-MABP between the two groups during and after surfactant administration.Our results suggest that cerebral autoregulation may be affected transiently by surfactant administration.The effect duration of LISA is shorter than that of INSURE（〈5 min in LISA vs.5–10 min in INSURE）.

Population-based frequency of surfactant dysfunction mutations in a native Chinese cohort

Background: Rare mutations in surfactant-associatedgenes contribute to neonatal respiratory distress syndrome.The frequency of mutations in these genes in the Chinesepopulation is unknown.Methods: We obtained blood spots from the GuangxiNeonatal Screening Center in Nanning, China thatincluded Han (n=443) and Zhuang (n=313) ethnic groups.We resequenced all exons of the surfactant proteins-B(SFTPB), -C (SFTPC), and the ATP-binding cassettemember A3 (ABCA3) genes and compared the frequenciesof 5 common and all rare variants.Results: We found minor differences in thefrequencies of the common variants in the Han andZhuang cohorts. We did not find any rare mutations inSFTPB or SFTPC, but we found three ABCA3 mutationsin the Han [minor allele frequency (MAF)=0.003] and 7 inthe Zhuang (MAF=0.011) cohorts (P=0.10). The ABCA3mutations were unique to each cohort;five were novel.The collapsed carrier rate of rare ABCA3 mutations inthe Han and Zhuang populations combined was 1.3%,which is signifi cantly lower than that in the United States(P<0.001).Conclusions: The population-based frequency ofmutations in ABCA3 in south China newborns is signifi cantlylower than that in United States. The contribution of theserare ABCA3 mutations to disease burden in the south Chinapopulation is still unknown.