Usefulness of stable microbubble test of tracheal aspirate for the diagnosis of neonatal respiratory distress syndrome

Objectives: To compare the overall accuracy of the stable microbubble test (SM test) with measurement of level of surfactant protein A (SP-A) of tracheal aspirate for the diagnosis of respiratory distress syndrome (RDS).
Methodology: Tracheal aspirates were obtained from neonates on ventilatory support. The SM test was carried out on specimens of tracheal aspirate immediately after collection. Levels of SP-A in tracheal aspirates were determined by enzyme-linked immunosorbent assay (ELISA) method. The results of the SM test and SP-A level of the tracheal aspirates were compared against the clinical diagnosis of RDS based on clinical, radiological and bacteriological findings.
Results: Both the median microbubble counts (6 microbubbles/mm,² range = 0–90) and median SP-A levels (100μg/L, range = 0–67 447) of infants with RDS were significantly lower than those of infants with no obvious lung pathology ( P <0.0001), and pneumonia ( P <0.0001). The SM test of tracheal aspirates had higher overall accuracy for the diagnosis of RDS than measurement of SP-A levels (94.6% vs 82.4%). When the receiver operating characteristic (ROC) curves of both tests for RDS were compared, the area under the ROC curve of the SM test was larger (0.9689) than that of the SP-A method (0.8965).
Conclusions: This study showed that the SM test of tracheal aspirate was a useful bedside diagnostic test for RDS. It could be carried out at any time after birth on infants requiring ventilatory support.     

Disturbed surface properties in preterm infants with pneumonia

Congenital pneumonia in preterm infants is often associated with respiratory insufficiency requiring mechanical ventilation. This study was performed to show whether pneumonia in these infants is associated with an inhibition or deficiency of surfactant. The ratio of lecithin and sphingomyelin (L/S ratio) and minimal surface tension were determined in pharyngeal aspirates from 90 term born infants (healthy) and in tracheal aspirates from preterm infants with wet lung (n = 13), congenital pneumonia (n = 21) and respiratory distress syndrome (RDS) (n = 90). The L/S ratio was lower (p < 0.0001) in the RDS group (8.6) when compared with healthy (48.6), wet lung (42.9) and pneumonia (28.9). Surface tension was higher (p < 0.001) in RDS (37 mN/m) and pneumonia (33.7) when compared with healthy (22.9) or wet lung (21.2). For infants with RDS, L/S ratio <16.5 detects surfactant deficiency with 96% specificity and 70% sensitivity, surface tension >29 mN/m represents surfactant inhibition (specificity 97%, sensitivity 92%). Using these cut-off values in infants with pneumonia, 81% had a sufficient amount of surfactant but only 21% of infants with pneumonia had appropriate surface tension. Our study shows that lung effluent of respiratory insufficient infants with pneumonia, who need mechanical ventilation, has disturbed surface properties despite a sufficient amount of surfactant. In these infants, surfactant substitution could be beneficial.     

Evaluation of surfactant function at birth determined by the stable microbubble test in term and near term infants with respiratory distress

Surfactant function using the stable microbubble test (SMT) was investigated in term or near term infants with respiratory distress. Newborn infants 34 weeks gestation with an initial clinical hypothesis of transient tachypnoea of the newborn (TTN) needing supplemental oxygen and controls were included. Gastric aspirates were collected immediately after birth for SMT. The first chest X-ray films were examined by three independent radiologists and according to their interpretation the babies were divided into a TTN, a respiratory distress syndrome of the newborn (RDS), or a poorly-defined X-ray group. A total of 32 infants with respiratory distress and 32 controls with similar gestational age and birth weight were studied. The median and interquartile range (IQR) of the stable microbubble (SMB) count was significantly lower (P<0.001) for the respiratory distress group than for the control group (17; range 6–33 versus 120; range 79–275). The proportion of babies with less than 35 stable microbubbles/mm² (SMB/mm²) was significantly different for the whole respiratory distress group (24/32–75%) and for the TTN (9/13–69%), the RDS (5/5–100%), and the poorly-defined (10/12–83%) groups as compared with the controls (2/32–6%; P<0.05). A total of 24/26 babies (92%) who needed oxygen for 24 h but only 1/6 (17%) of them who needed <24 h had a bubble count of less than 35 SMB/mm² (P<0.05). Conclusion: the results suggest that deficiency or dysfunction of the surfactant system is involved in the majority of cases of respiratory distress in near term and possibly term babies. The stable microbubble test can enable clinicians to take an earlier decision to give surfactant to term or near term infants with more severe and progressive respiratory distress.Abbreviations RDS respiratory distress syndrome of the newborn - SMB stable microbubbles - SMT stable microbubble test - TTN transient tachypnoea of the newborn     

Endogenous surfactant metabolism in newborn infants with and without respiratory failure

Studies using stable isotopically labeled glucose and palmitate as precursors of pulmonary surfactant synthesis have demonstrated slow surfactant turnover in premature infants with respiratory distress syndrome (RDS). However, only limited data about surfactant turnover are available for term infants. Because acetate is a direct precursor of de novo synthesized surfactant fatty acid, we measured [1-13C1]acetate incorporation into surfactant of term infants without respiratory dysfunction (control group), preterm infants with RDS, and term infants with primary respiratory failure to determine whether stable isotopically labeled acetate would yield similar results to previous studies of preterm infants with RDS and, furthermore, would distinguish normal from abnormal surfactant turnover. Despite similar amounts of phospholipids and acetate precursor enrichment, the control group had higher fractional synthetic rate and shorter half-life of clearance than preterm infants with RDS, (fractional synthetic rate, 15.4 +/- 2.4 versus 2.2 +/- 0.4%/d, p < 0.001; half-life of clearance, 27 +/- 3 versus 105 +/- 11 h, p < 0.001). Term infants with severe respiratory failure had a lower fractional synthetic rate than those with mild disease (2.9 +/- 0.6 versus 13.8 +/- 3.5%/d, p = 0.014) and a reduced amount of phospholipids recovered from tracheal aspirates (54 +/- 17 versus 300 +/- 28 nmol, severe versus mild disease, respectively, p < 0.001). The amount of phospholipids in tracheal aspirates correlated inversely with disease severity, (r = -0.75, p = 0.01). We conclude that normal surfactant turnover in term infants is faster than in preterm infants with RDS. Surfactant turnover in term infants with severe respiratory failure is similar to that of preterm infants with RDS, suggesting either delayed maturity of the surfactant system or disruption from the underlying disease process.     

胃液稳定微泡实验早期诊断早产儿呼吸窘迫综合征

目的：早产儿呼吸窘迫综合征(RDS)需要做出早期诊断才能指导呼吸机和肺表面活性物质的及时使用。该研究的目的是明确胃液稳定微泡实验(stab le m icrobubb le test,SMT)早期诊断早产儿RDS的价值,为预防性使用肺表面活性物质提供指导。方法：对101例收治于日本岩手医科大学新生儿重症监护室的早产儿,胎龄31±3.5周,(24~35周,)生后30 m in内取胃液做SMT,低倍镜下数出每mm2中直径<15μm的稳定微泡数;1 h内拍胸片,以临床表现及X线结果作为诊断早产儿RDS的金标准。计算SMT早期诊断早产儿RDS的敏感度、特异度及阳性、阴性预测值,观察以SMT结果指导肺表面活性物质使用的临床价值。结果：101例早产儿中诊断为RDS者31例,其中微泡数<10个/mm2者22例,10~20个/mm2者7例,>20个mm2者2例;非RDS者共70例,其中<10个/mm2者仅1例,10~20个/mm2者2例,>20个mm2者67例。以胃液微泡数<10个/mm2作为界值,SMT预测并早期诊断RDS的敏感度及特异度分别为70.97%和98.57%,阳性预测值及阴性预测值分别为95.65%和88.46%;以胃液微泡数<20个/mm2作为界值,SMT预测并早期诊断RDS的敏感度及特异度分别为93.55%和95.71%,阳性预测值及阴性预测值分别为90.63%和97.10%。微泡数<10个/mm2者均接受肺表面活性物质替代治疗,临床效果显著。结论：SMT法简便、快速、经济,敏感度高,特异性好,能预测并早期诊断早产儿RDS,有助于指导肺表面活性物质的预防性使用,有极高的临床应用价值,值得在国内推广。     

Ureaplasma urealyticum respiratory infection in newborn infants]

The neonatal respiratory infection by Ureaplasma urealyticum is rare, but it could represent a major risk for the newborn infants. CASE REPORTS: A term newborn infant presented an early respiratory distress with persistent pulmonary hypertension, requiring artificial ventilation and inhaled nitric oxide therapy. Tracheal aspirates were positive for Ureaplasma urealyticum, although his mother was not contamined. A preterm newborn infant (gestational age: 33 weeks) presented a severe respiratory distress, requiring mechanical ventilation. The tracheal aspirates we positive for Ureaplasma urealyticum, as well as his mother's cervico-vaginal swab. Both recovered thanks to antibiotics (intravenous macrolid during ten days). The outcome was favorable for both babies. CONCLUSION: Neonatal infection due to Ureaplasma is serious. The clinical diagnosis is difficult, recalling group B streptococcal infection. Clinical aggravation, despite antibiotics associated with negative bacteriological standard detection, leads one to evoke this diagnosis and perform specific bacteriological cultures.     

Thrombomodulin serum levels in ventilated preterm babies with respiratory distress syndrome

A soluble form of thrombomodulin (TM), an anticoagulant proteoglycan of the endothelial cell membrane, considered a marker of vascular endothelial damage, was measured in plasma of preterm infants with respiratory distress syndrome (RDS). In these patients, lung immaturity leads to endothelial leak of plasma proteins and to surfactant inhibition. In 18 babies with RDS, plasma TM concentration was significantly elevated compared with values of a matched group of babies without pulmonary disease (276.1 ng/ml vs 141.3 ng/ml) (P<0.05). Furthermore, TM levels of mechanical ventilated babies (IPPV) with severe RDS were higher than those of babies with moderate RDS and treated with nasal CPAP (340.9 ng/ml vs 174.2 ng/ml) (P<0.05). Conclusion These data show that TM can be used as marker of pulmonary endothelial damage in preterm babies treated with mechanical ventilation for RDS and suggest early intervention with exogenous surfactant to limit alveolar protein leakage and surfactant inactivation. Received: 20 February 1997 and in revised form: 7 July 1997 / Accepted: 8 July 1997     

Early surfactant for neonates with mild to moderate respiratory distress syndrome: a multicenter, randomized trial

OBJECTIVE: We studied the efficacy and safety of electively providing surfactant to preterm infants with mild to moderate respiratory distress syndrome (RDS) not requiring mechanical ventilation. STUDY DESIGN: A 5-center, randomized clinical trial was performed on 132 infants with RDS, birth weight >or=1250 grams, gestational age or=40% for >or=1 hour, and no immediate need for intubation. Infants were randomly assigned to intubation, surfactant (Survanta, Ross Laboratories, Columbus, Ohio) administration, and expedited extubation (n=65) or expectant management (n=67) with subsequent intubation and surfactant treatment as clinically indicated. The primary outcome was duration of mechanical ventilation. RESULTS: Infants in the surfactant group had a median duration of mechanical ventilation of 2.2 hours compared with 0.0 hours for control infants, since only 29 of 67 control infants required mechanical ventilation (P=.001). Surfactant-treated infants were less likely to require subsequent mechanical ventilation for worsening respiratory disease (26% vs 43%, relative risk=0.60; 95% CI, 0.37, 0.99). There were no differences in secondary outcomes (duration of nasal continuous positive airway pressure, oxygen therapy, hospital stay, or adverse outcomes). CONCLUSIONS: Routine elective intubation for administration of surfactant to preterm infants >or=1250 grams with mild to moderate RDS is not recommended.     

Surfactant Apoprotein A (SP-A) in Tracheal Aspirates of Newborn Infants with RDS

Human pulmonary surfactant contains four groups of apoproteins, SP-A, B, C and D. We determined the concentration of SP-A in the tracheal aspirate of newborn infants by a two-site simultaneous immunoassay with monoclonal antibodies, and used this assay to assess changes in surfactant in various clinical situations. SP-A concentrations were standardized per milligram of albumin in the aspirate. The ratio of SP-A/albumin (µg/mg) in tracheal aspirates of 18 preterm infants with respiratory distress syndrome (RDS), in which samples were obtained within 12 hours of birth, was significantly lower (0.2 ± 0.1/µg/mg, mean ± S.D.) compared to a group of 20 non-RDS preterm infants of similar gestational age (15.8±7.4µg/mg) (p<0.05). None of the RDS infants had a SP-A/albumin ratio above l/µg/mg within 12 hours of birth, but the ratio exceeded 5µg/mg in all samples from non-RDS infants. The SP-A/albumin ratio significantly increased, however, at 48 to 72 hours after birth in infants with RDS (15.7 ± 9.5µg/mg). During the recovery phase of RDS, no difference was evident in the SP-A/albumin ratio in babies treated with artificial surfactant compared to those not treated .     

Endogenous pulmonary surfactant metabolism is not affected by mode of ventilation in premature infants with respiratory distress syndrome

OBJECTIVE: To determine if high frequency oscillatory ventilation (HFOV) decreases surfactant production in premature infants with respiratory distress syndrome (RDS). STUDY DESIGN: We randomized 19 infants <28 weeks of gestation to either HFOV (n = 8) or conventional ventilation (CV, n = 11) at 24 hours of life. After a 24-hour continuous infusion of uniformly labeled carbon 13 glucose (U-(13)C(6)) glucose, we measured (13)C enrichment in surfactant phosphatidylcholine (PC) in tracheal aspirate samples using gas chromatography/mass spectrometry. We calculated the fractional synthetic rate (FSR) of surfactant PC from labeled glucose and its half-life of clearance (T(1/2)). RESULTS: FSR did not differ between groups (4.7% +/- 2.7%/day CV vs 4.2% +/- 3.1%/day HFOV, P =.7). T(1/2) was 79 +/- 18 hours in the CV group and 76 +/- 23 hours in the HFOV group (P =.7). Neither degree of ventilatory support nor supplemental oxygen exposure correlated with surfactant metabolic indices. Three of 4 infants who died from RDS within the first month of life had a shorter T(1/2) than 14 of 15 infants who survived. CONCLUSION: Surfactant metabolism is similar in preterm infants ventilated with HFOV and CV. Shortened surfactant half-life may characterize a subset of preterm infants with lethal RDS.     

Surfactant Replacement Therapy for the Prevention of the Neonatal Respiratory Distress Syndrome in Preterm Infants

Objective To study the efficacy of pulmonary surfactant (Exosurf) in the prevention of the neonatal respiratory distress syndrome (RDS) in preterm infants. Methods A prospective clinical trial was conducted. To prevent RDS, a single dose of pulmonary surfactant (Exosurf) was administered intratracheally in 25 preterm infants at a high risk of developing RDS as the prophylaxis group, and another 25 preterm babies who received no surfactant administration formed the control group. Results The preterm infants in the prophylaxis group received a prophylactic dose of surfactant ( 67.5 mg/kg) within 0.25 to 6 hours ( 3.4± 1.9 hours) after delivery. Oxygenation in these babies was markedly improved and their clinical symptoms were relieved after the administration of surfactant. The durations of supplemental oxygen administration, assisted ventilation and hospitalization in the prophylaxis group, were ( 9.5± 6.9) days, ( 2.6± 3.8) days and ( 40.8± 17.8) days respectively, which were significantly shortened compared with those of the control group (P< 0.05). Although the incidence of RDS and mortality in the prophylaxis group (20% and 8%) seemed to be lower than those of the control group (32% and 12%),there was no statistical differenc (P> 0.05). Conclusions Prophylactic administration of surfactant can improve oxygenation, relieve symptoms, and shorten the duration of supplemental oxygen administration, assisted ventilation and hospitalization. It has a relief effect on RDS in preterm infants.     

Early nasal intermittent positive pressure ventilation versus continuous positive airway pressure for respiratory distress syndrome

Aim:  To determine whether early nasal intermittent positive pressure ventilation (NIPPV), in comparison to early continuous positive airway pressure (CPAP), can reduce the need for intubation and mechanical ventilation in preterm neonates with suspected respiratory distress syndrome (RDS).
Methods:  In this stratified open-label randomized controlled trial, neonates (28–34 weeks gestation) with respiratory distress within 6 h of birth and Downe's score ≥ 4 were eligible. Subjects were randomly allocated to 'early-NIPPV' or 'early-CPAP' after stratifying for gestation (28–30 weeks, 31–34 weeks) and surfactant use. Primary outcome was failure of the allocated mode within 48 h.
Results:  Seventy-six neonates were enrolled (37 in 'early-NIPPV' and 39 in 'early-CPAP' groups). Failure rate was less with 'early-NIPPV' versus 'early-CPAP'[13.5% vs. 35.9%, respectively, RR 0.38 (95% CI 0.15–0.89), p = 0.024]. Similarly, need for intubation and mechanical ventilation by 7 days (18.9% vs. 41%, p = 0.036) was less with NIPPV. Failure rate with NIPPV was less in the subgroups of subjects born at 28–30 weeks (p = 0.023) and who did not receive surfactant (p = 0.018).
Conclusion:  Among preterm infants with suspected RDS, early use of NIPPV reduces the need for intubation and mechanical ventilation compared to CPAP.     

New developments in neonatal respiratory management

Respiratory distress syndrome (RDS) is the major cause of respiratory failure in preterm infants due to immature lung development and surfactant deficiency. Although the concepts and methods of managing respiratory problems in neonates have changed continuously, determining appropriate respiratory treatment with minimal ventilation-induced lung injury and complications is crucially important. This review summarizes neonatal respiratory therapy's advances and available strategies (i.e., exogenous surfactant therapy, noninvasive ventilation, and different ventilation modes), focusing on RDS management.     

Rapid diagnosis of respiratory distress syndrome by oral aspirate in premature newborns

ObjectiveThe stable microbubble test on gastric aspirate and on amniotic fluid has been used for the diagnosis of respiratory distress syndrome in the newborn. However, no study has performed this test on oral aspirates from premature infants. The objective of this study was to evaluate the performance of the stable microbubble test on oral aspirates from preterm newborns to predict respiratory distress syndrome.MethodThis study included infants with gestational age <34 weeks. Oral fluids were obtained immediately after birth and gastric fluids were collected within the first 30 minutes of life. The samples were frozen and tested within 72 hours.ResultsThe sample was composed of paired aspirates from 64 newborns, who were divided into two groups: respiratory distress syndrome group (n = 21) and control group (n = 43). The median (interquartile range) of the stable microbubble count in the oral samples of infants with respiratory distress syndrome was significantly lower than that of infants who did not develop respiratory symptoms: respiratory distress syndrome group = 12 (8–22) stable microbubbles/mm²; control group = 100 (48–230) microbubbles/mm² (p < 0.001). The correlation between microbubble count in gastric and oral aspirates was 0.90 (95% confidence interval = 0.85–0.95; p < 0.001). Considering a cut-off point of 25 microbubbles/mm², the sensitivity and the specificity of the stable microbubble test were 81.4% and 85.7%, respectively.ConclusionThe study suggests that the stable microbubble test performed on oral aspirate is a reliable alternative to that performed on gastric fluid for the prediction of respiratory distress syndrome in the newborn.     

Prediction of respiratory distress syndrome by the microbubble stability test on gastric aspirates in newborns of less than 32 weeks' gestation

AIM: There is a need for a rapid method to identify infants who will develop respiratory distress syndrome (RDS) soon after birth, to allow early treatment of affected infants with surfactant. The microbubble stability test (MST) may be one such method, but clinical experience is sparse. METHODS: The MST was performed on gastric aspirates from 188 infants with a mean gestational age of 29 (range 23-31) wk. RESULTS: 87 infants developed moderate to severe RDS, corresponding to a prevalence of 46%. The sensitivity, specificity and predictive values for identification of infants with moderate to severe RDS were determined for the average diameter of bubbles, the proportion of microbubbles with different diameters and the total number of microbubbles. The proportion of microbubbles with diameters <20 or 25 microm gave the best prediction, with a sensitivity of 78-79%, a specificity of 57-58%, a positive predictive value of 62% and a negative predictive value of 76%. Early treatment with nasal continuous positive airway pressure probably mitigated the development of RDS in some infants with a low-degree surfactant deficiency and this may explain the relatively low specificity. CONCLUSION: In infants of <32 wk gestation RDS can be predicted by computerized image analysis of the size distribution of microbubbles generated in gastric aspirates.     

Randomized study of nasal continuous positive airway pressure in the preterm infant with respiratory distress syndrome

Aim: To evaluate whether very preterm babies can be extubated successfully to nasal continuous positive airway pressure (nCPAP) within one hour of birth after receiving one dose of surfactant in the treatment of respiratory distress syndrome (RDS). Methods: Forty-two infants of 25 to 28[Formula: See Text] wk of gestation were intubated at birth and given one dose of surfactant. They were then randomized within one hour of birth to either continue with conventional ventilation or to be extubated to nCPAP. Results: Eight out of 21 (38%) babies randomized to nCPAP did not require subsequent reventilation. (Ventilation rates of 62% vs 100%, p = 0.0034). The smallest baby successfully extubated weighed 745 g. There were also significantly fewer infants intubated in the nCPAP group at 72 h of age (47% vs 81%, p = 0.025). There was no significant difference between the two groups in the number of babies that died, developed chronic lung disease or severe intraventricular haemorrhage.

Conclusion: A significant number of very preterm babies with RDS can be extubated to nCPAP after receiving one dose of surfactant. nCPAP is a potentially useful modality of respiratory support even in very premature infants.     

Continuous positive airway pressure - a gentler approach to ventilation

Continuous positive airway pressure (CPAP) has become a useful modality in management of respiratory distress, especially in preterm babies. Main indications for use of CPAP are respiratory distress syndrome (RDS) and apnea of prematurity. It decreases the need of invasive and costly mechanical ventilation. This review details the physiological effects of CPAP, its methods of delivery, and its need in a country like India. It also describes the guidelines for initiating and weaning CPAP. The review concludes that use of CPAP in respiratory distress syndrome is associated with lower rates of failed treatment, decreased incidence of chronic lung disease and lower overall mortality, specially in infants with birth weight above 1500 grams. Early use of CPAP is more beneficial, Surfactant and CPAP act in conjunction for babies with RDS. CPAP is a low-cost, simple and noninvasive option for a country like India, where most places lack facilities of mechanical ventilation. Systematic reviews, randomized and quasi-randomized trials by searching MEDLINE and the Cochrane Library formed the basis of this update.     

Surfactant proteins and stable microbubbles in tracheal aspirates of infants with respiratory distress syndrome: relation to the degree of respiratory failure and response to exogenous surfactant

 Surfactant proteins (SP-A and SP-BC), albumin (ALB), and stable microbubble (SM) count were measured in tracheal aspirates from infants with respiratory distress syndrome (RDS) receiving single-dose Surfactant-TA (surfactant group, n = 32) or no surfactant (control group, n = 12), and those without RDS (non-RDS group, n = 8) to determine biochemical and biophysical status of surfactant in the course of RDS after surfactant replacement. Surfactant therapy resulted in immediate and sustained elevations of SP-BC/ALB and SM count with a rapid fall in ventilatory index to levels measured in the non-RDS group, whereas these indices improved slowly in the control group. The SP-A/ALB was initially low in both RDS groups and increased to levels measured in the non-RDS group by age 48 h. Multiple regression analysis showed that SP-BC/ALB, postnatal age, SM count, SM count/SP-A plus SP-BC, and surfactant therapy were independently associated with the severity of RDS as assessed by ventilatory index (r = 0.75, P < 0.0001; number of samples = 256). Infants with a relapse response to surfactant (n = 9) had levels of SP-A/ALB and SP-BC/ALB similar to those measured in the sustained group (n = 23), but had significantly lower SM count and SM count/SP-A plus SP-BC between 24 and 96 h of age. Conclusion Surfactant therapy normalizes the sur factant and respiratory status of infants with RDS. Surfactant dysfunction rather than depletion may explain the relapse response seen in some surfactant recipients. Received: 23 October 1995 / Accepted: 20 May 1996     

肺表面活性物质对不同胎龄呼吸窘迫综合征新生儿的疗效

目的 探讨肺表面活性物质(PS)对不同胎龄儿呼吸窘迫综合征(RDS)的疗效差异.方法 选择胎龄28～39周,出生体质量760～3 240 g,经PS治疗的RDS患儿67例.早期组:胎龄28～30周的早期早产儿18例;中期组:胎龄31～33周的中期早产儿28例;晚期组:胎龄34周以上的晚期早产儿和足月儿21例.比较3组PS治疗时RDS的重症程度、PS开始使用时间、第1次使用剂量、总剂量、重复使用例数、氧疗时间、最高吸氧体积分数(FiO2)、机械通气时间等指标.结果 PS治疗时早期组和中期组轻度RDS例数明显多于晚期组(Pa＜0.05).中期组和晚期组重度RDS例数明显多于早期组(Pa＜0.05),PS开始使用时间晚期组明显晚于早、中期组(Pa＜0.05).第1次使用剂量早期组明显多于中、晚期组(Pa＜0.05).使用总剂量和重复使用例数各组间均无统计学差异(Pa＞0.05).机械通气时间早、晚期组明显多于中期组(P=0.040);最高FiO2以晚期组最高(P=0.006).结论 早期早产儿RDS病情轻、开始PS治疗时间早、剂量足,但需氧疗和机械通气时间长;晚期早产儿和足月儿RDS病情危重、开始PS治疗时间晚、剂量不足、需氧疗和机械通气时间长.对晚期早产儿和足月儿RDS治疗应尽早、足量使用PS.     

呼吸窘迫综合征极低出生体重儿解脲脲原体感染与支气管肺发育不良的关系

目的 探讨并发新生儿呼吸窘迫综合症（RDS）的极低出生体重儿下呼吸道分泌物解脲脲原体（UU）感染与支气管肺发育不良（BPD）的关系。方法 选取73例诊断为RDS、早期使用机械通气治疗且至少应用1剂肺表面活性物质的极低出生体重儿,采用荧光定量聚合酶链反应法检测气管内吸出物UU核酸,分为UU感染组（n=21）和非感染组（n=52）,比较两组临床特点及BPD的发生率。结果 UU感染组阴道产百分率及反复院内肺部感染、胎膜早破发生率均高于非感染组;胎膜早破持续时间长于非UU感染组;且吸氧时间及住院时间均长于非UU感染组。UU感染组生后3 h内血浆免疫球蛋白IgM、白细胞计数、中性粒细胞绝对值显著高于非UU感染组。73例患儿中,发生BPD 45例,其中UU感染组BPD发生率（90%,19/21）显著高于非UU感染组（50%,26/52）,差异有统计学意义（P结论 下呼吸道UU感染可增加RDS 极低出生体重儿BPD的发生率。