多普勒血流频谱法估测肺出血新生儿肺动脉压的研究

目的　研究肺出血新生儿心脏收缩功能和肺动脉压力变化及临床影响因素。方法　用M型二维超声多普勒和脉冲多普勒方法分别测定28例肺出血新生儿和28例非肺出血新生儿(含17例正常新生儿)心脏收缩功能及主肺动脉血流速度频谱,以肺动脉血流峰速时间/右室射血时间(TPV/RVET)比值反映肺动脉压力,分析肺出血新生儿心脏收缩功能和肺动脉压力变化及临床影响因素。结果　肺出血新生儿TPV/RVET比值(0.253±0.041)明显低于正常对照组(0.329±0.058)和非肺出血组(0.301±0.022)(P＜0.01);肺出血新生儿恢复期该比值(0.294±0.033)升高,肺出血死亡组TPV/RVET比值(0.219±0.022)和缩短分数［FS(31±5)%］明显低于存活新生儿(0.270±0.031,TPV/RVET39±7,FS)(P＜0.01);TPV(52±12)ms明显低于存活新生儿(44±8)(P＜0.05)。早产儿肺出血组TPV明显缩短(P＜0.01)。肺出血组TPV/RVET比值与动脉血pH值高度相关(r=0.84,P＜0.01)。结论　肺出血新生儿伴有肺动脉压力升高,严重者心脏收缩功能降低,导致心力衰竭,致新生儿死亡。     

新生儿呼吸窘迫综合征肺动脉压力动态变化及其与血清内皮素-1和一氧化氮关系的研究

目的研究新生儿呼吸窘迫综合征(RDS)肺动脉压力动态变化及其与血清内皮素-1(endothelin-1,ET-1)、一氧化氮(nitric oxide,NO )的关系.方法对13例确诊为新生儿RDS患儿(实验组)和20例正常新生儿(对照组)用脉冲超声多谱勒分别于生后2、12、24、48、72 h测定肺动脉血流加速时间(TPV)及右心室射血时间(RVET),以TPV/RVET比值反映肺动脉压力.用硝酸还原酶法和放射免疫法分别测定实验组和对照组新生儿生后24、72 h血清ET-1和NO的水平.结果实验组和对照组新生儿肺动脉压力在生后2、12及72 h差异无显著意义(t值分别为1.25、1.84、0.94,P均>0.05);实验组24、48 h TPV/RVET比值为0.277±0.076、0.278±0.027,对照组分别为0.321±0.051、0.329±0.062,两组相比差异有显著意义(t值分别为2.86、2.20,P＜0.01、 <0.05);实验组和对照组在生后24 h时ET-1[(62±23)ng/L、(47±8)ng/L]、NO[(11±10) μmol/L、(32±22) μmol/L]水平相比,差异有显著意义(t值分别为2.33、2.37,P均<0.05);而72 h时差异无显著意义(t值分别为0.87、1.93,P均＞0.05),与肺动脉压力变化相一致.死亡组肺动脉压力(0.25±0.02)明显高于存活组(0.28±0.03, t=2.35, P＜0.05);死亡组患儿ET-1水平[(91±27)ng/L]明显高于存活组[(39±9)ng/L],差异有显著意义(t=4.97,P＜0.01);死亡组患儿NO水平为(5±4) μmol/L,明显低于存活组的(32±28) μmol/L, 差异有显著意义(t=2.38,P＜0.05);实验组RDS患儿生后24 h其血清ET-1水平与肺动脉压力呈正相关y=302.3x-861.2,NO水平与肺动脉压力呈负相关y=-98.3x+400.8.结论新生儿RDS患儿肺动脉压力较正常儿高,持续时间较长,且易合并持续肺动脉高压.血清ET-1水平与肺动脉压力呈正相关,NO水平与肺动脉压力呈负相关.     

Cardiovascular effects of dexamethasone in the preterm infant.

Twenty preterm infants were studied serially with Doppler echocardiography to document changes in pulmonary artery pressure, myocardial thickness, and patent ductus arteriosus associated with dexamethasone treatment for chronic lung disease. Pulmonary artery pressure was assessed with Doppler, by its inverse correlation with the ratio of the pulmonary artery time to peak velocity (TPV) and right ventricular ejection time (RVET). Eleven of the 20 infants showed an increase in TPV/RVET after commencing steroids, suggesting a fall in pulmonary artery pressure. This change was not sustained in most cases and had no correlation with the improvement in respiratory status. Ventricular septal and left ventricular posterior wall thickness increased in all 11 infants in whom it was measured. The median increase was respectively 0.9 and 0.8 mm. In most infants this increase was small, less than 1 mm, however two infants developed marked septal hypertrophy with Doppler evidence of left ventricular outflow tract obstruction. Dexamethasone had no consistent closing effect on a patent ductus arteriosus in four infants. Myocardial hypertrophy occurs in most infants, in some it is severe. It would seem prudent to monitor echocardiographically for this side effect.     

Subclinical persisting pulmonary hypertension in chronic neonatal lung disease.

The development of pulmonary hypertension is one of the adverse factors in the outcome of infants with chronic neonatal lung disese (CNLD). The purpose of this cross sectional study was to evaluate the prevalence and degree of pulmonary hypertension in a cohort of survivors of CNLD stable in air. Pulmonary artery pressure was assessed using its inverse correlation with the ratio of time to peak velocity and right ventricular ejection time (TPV:RVET) as measured from Doppler velocity time signals in the main pulmonary artery. A normal ratio is > or = 0.35, a possibly low ratio lies between 0.31 and 0.35, and a definitely low ratio is < 0.31. The subjects were divided into three groups. Group A comprised 58 infants with oxygen dependence and an abnormal chest radiograph at 28 days of age; group B comprised 18 infants with oxygen dependence and a normal chest radiograph at 28 days of age; and group C (controls) comprised 21 siblings without oxygen dependence by 10 days and a normal chest radiograph. There were significant differences in mean (SD) TPV:RVET ratio between group A 0.346 (0.045), group B 0.335 (0.057), and groups A + B 0.344 (0.048) when compared with group C controls 0.385 (0.034). The prevalence of a definitely low TPV:RVET ratio suggesting a raised pulmonary artery pressure was 19% in group A, 39% in group B, 24% in groups A + B, and none in group C. There were no clinical signs of pulmonary hypertension in any patient studied. Stepwise multiple linear regression failed to find significant associations with antenatal or neonatal putative risk factors. Additionally, there were no associations with childhood respiratory morbidity. These data suggest a high prevalence of subclinical pulmonary hypertension in CNLD patients. It is speculated that occult hypoxaemia may be occurring in this group of infants.     

Coagulation and fibrinolytic systems in the ill preterm newborn

Aim: The activation pattern of the clotting and fibrinolytic systems in 63 preterm infants (GA 31, 6 ± 2.3 weeks) was studied. Methods: The infants were divided into four groups: (i) IRDS, (ii) asphyxia at birth, (iii) sepsis, and (iv) mild infection. A control group was composed of preterm infants without any apparent disease (GA 32 ± 1.8 weeks). Results: During IRDS we found a systemic activation of both coagulation and fibrinolysis at birth which was represented by lower levels of ATIII (27.7 ± 8.8%) and significantly greater levels of TAT (37.9 ± 31.9 ng/ml), D-dimers (1242.7 ± 206.9 ng/ml), tPA Ag (10.9 ± 5.3 ng/ml) and PAI Ag (59.9 ± 16.7 ng/ml) than in the control group. In the asphyxiated newborns there were no significant differences from the controls. During their seventh day of life, a significant reduction of all the analysed parameters (TAT, D-dimers, tPA, PAI) and a significant increase in ATIII were seen in the newborns with IRDS, while no significant modification was observed in the newborns with asphyxia at birth. When the newborns with sepsis were compared with those with mild infection, their TAT and PAI values proved to be significantly higher for the first tests (21.7 ± 18.8 vs 9.2 ± 6.9 μgA and 53.6 ± 14.4 vs 37.7 ± 10.2 ng/ml respectively). During the second tests, 7 days later, only TAT (16.7 ± 14.7 vs 6.3 ± 4 jtg/1) levels remained high while D-dimers (1094.2 ± 400.6 vs 646 ± 200 ng/ml) and tPA (11.3 ± 8 vs 4.9 ± 2 ng/ml) were significantly higher in the septic group of newborns than those with mild infection. Conclusions: These data indicate that there is an activation of the clotting and fibrinolytic systems both in the initial phase of IRDS as well as during sepsis.     

Doppler assessment of pulmonary artery pressure in neonates at risk of chronic lung disease

AIM—To evaluate the pulmonary artery pressure (PAP) change in very low birthweight (VLBW) infants at risk of chronic lung disease (CLD).
METHODS—The time to peak velocity:right ventricular ejection time (TPV:RVET) ratio calculated from the pulmonary artery Doppler waveform, which is inversely related to PAP, was used. The TPV:RVET ratio was corrected for different heart rate (TPV:RVET(c)). Seventy three VLBW infants studied on days 1, 2, 3, 7, 14, 21 and 28 were enrolled for the analysis.
RESULTS—Twenty two infants developed CLD with a characteristic chest radiograph at day 28. Fifty one did not, of whom 17 were oxygen dependent on account of apnoea rather than respiratory disease, and 34 were non-oxygen dependent. The TPV:RVET(c) ratio rose progressively in all three groups over the first three days of life, suggesting a fall in PAP. In the oxygen and non-oxygen dependent groups, the mean (SD) ratio rose to 0.53 (0.09) and 0.57 (0.09), respectively, on day 7, then remained relatively constant thereafter. The CLD group rose more slowly after day 3 and had a significantly lower mean ratio from day 7 onwards compared with the other two groups (day 7: P<0.001, days 14-28: P<0.0001), and fell significantly from 0.47 (0.11) on day 7 to 0.41 (0.07) on day 28 (P=0.01), suggesting a progressive rise in PAP. The mean (SD) ratios at day 28 of all infants were: CLD group 0.41 (0.07); oxygen dependent group 0.66 (0.15); and the non-oxygen group 0.67 (0.11). The CLD group had a significantly lower ratio than the oxygen dependent group and the non-oxygen group (P<0.0001). Using the TPV:RVET(c) ratio of <0.46, infants at risk of developing CLD could be predicted on day 7 (predictive value 82.8%, sensitivity 54.5%, specificity 94.1%).
CONCLUSION—The non-invasive assessment of PAP using the TPV:RVET(c) ratio may be useful in the longitudinal monitoring of PAP change in VLBW infants, and for prediction of chronic lung disease.

     

Changes in pulmonary arterial pressure in preterm infants with chronic lung disease

BACKGROUND: Pulmonary arterial pressure (PAP) is raised in preterm infants with respiratory distress syndrome who subsequently develop chronic lung disease. The natural history of pulmonary hypertension in infants with chronic lung disease is unknown. OBJECTIVES: To investigate changes in PAP, assessed non-invasively using Doppler echocardiography, in infants with chronic lung disease during the 1st year of life. METHODS: Serial examinations were performed in infants with chronic lung disease and healthy preterm infants. The Doppler derived acceleration time to right ventricular ejection time ratio (AT/RVET) was calculated from measurements made from the pulmonary artery velocity waveform. RESULTS: A total of 248 examinations were performed in 54 infants with chronic lung disease and 44 healthy preterm infants. The median AT/RVET was significantly lower in infants with chronic lung disease than in healthy preterm infants (0.31 v 0.37). AT/RVET significantly correlated with age corrected for prematurity in both infants with chronic lung disease (r = 0.67) and healthy infants (r = 0.55). There was no significant difference between the rate of change in AT/RVET between the two groups. In infants with chronic lung disease, multivariate analysis showed that AT/RVET was significantly independently associated with age and inversely with duration of supplemental oxygen treatment. Median AT/RVET was significantly lower in infants with chronic lung disease until 40-52 weeks of age corrected for prematurity. CONCLUSIONS: Although PAP falls with increasing age in both infants with chronic lung disease and healthy preterm infants, it remains persistently raised in infants with chronic lung disease until the end of the 1st year of life.     

Raised pulmonary artery pressure in very low birthweight infants requiring supplemental oxygen at 36 weeks after conception.

This study aimed to investigate the changes in pulmonary artery pressure in infants with chronic lung disease who then developed prolonged oxygen dependency. The time to peak velocity: right ventricular ejection time (TPV:RVET) ratio calculated from the Doppler waveform, which correlates negatively with pulmonary artery pressure, was used. Thirty four infants with chronic lung disease were studied. At 36 weeks after conception 19 infants still required supplemental oxygen (POD group) and 16 infants were in air (controls). Over the first three weeks, there was a significant rise in the ratio in both groups, indicating a fall in pulmonary arterial pressure. From the third week onwards the ratio was significantly lower in the POD group. There was a significant rise in the ratio from four to 36 weeks after conception in the control group; the POD group showed a tendency towards a fall over the same time period. The requirement for supplemental oxygen almost mirrored the changes in the ratio in both groups but was not significantly different until the fifth week after birth. These data suggest that pulmonary arterial pressure has a significant role in the pathophysiology of prolonged oxygen dependency and may be important in the subsequent morbidity associated with this group of very low birthweight infants.     

CHESTWALL COMPLIANCE IN FULL-TERM AND PREMATURE INFANTS

Abstract. Gerhardt, T. and Bancalari, E. (Department of Pediatrics, University of Miami, Florida, U.S.A.) Chestwall compliance in full-term and premature infants. Acta Pediatr Scand, 69: 359, 1980.—Chestwall compliance was determined in 26 premature infants (BW 1 320±410 g, gest. age 32 weeks) and in 10 full-term infants (BW 3 155±810 g) who were ventilated mechanically. Chestwall compliance in premature infants was 6.4 ml/ (cmH₂O×kg), decreasing with advancing gestational age to 4.2 ml/(cmH₂O×kg) in full-term infants. There was a linear correlation ( r = 0.95 and 0.79 respectively) between tidal volume and the pressure transmitted to the esophagus throughout the tidal volume range. The portion of airway pressure transmitted to the esophagus depended on the infant's lung compliance. Only 5% was transmitted in infants with hyaline membrane disease, 12% in newborns with a patent ductus arteriosus, 17 % in normal prematures and 25% in normal full-term infants. The findings suggest that during mechanical ventilation the high chestwall compliance and low lung compliance of premature infants prevent a significant rise in intrapleural pressure which could interfere with central venous return and cardiac output. However, using high inspiratory pressures and continuous distending airway pressure in the absence of lung pathology may result in a decreased cardiac output. The highly compliant chestwall of the premature infant may exert insufficient outward recoil and might be one of the causes of a low functional residual capacity and chronic pulmonary failure in the premature infant.     

仰俯卧位对新生儿肺炎患儿肺功能的影响(英文)

目的　探讨仰、俯卧位对足月新生儿肺炎患儿肺功能的影响 ,寻求足月新生儿肺炎患儿的合理体位。方法　应用美国BicoreCP 10 0新生儿肺功能仪分别检测 30例新生儿肺炎患儿仰、俯卧位时的呼吸频率、潮气量、每分通气量、气道阻力、动态肺顺应性和呼吸功。结果　俯卧位呼吸频率和气道阻力明显低于仰卧位 [(4 4 .3±9.2bpm min)vs (4 8.0± 10 .6bpm min) ;(15 3.1± 5 0 .4 )cmH2 O (L .sec)vs (2 11.9± 6 3.1)cmH2 O (L .sec) ,差异有极显著性意义 ,P <0 .0 1];俯卧位潮气量、每分通气量、动态肺顺应性和呼吸功明显高于仰卧位 [(2 .2 9±0 .4 6ml kg)vs (1.6 5± 0 .5 0ml kg) ;(0 .0 95± 0 .0 2 4 )L (min .kg)vs (0 .0 75± 0 .0 2 2 )L (min .kg) ;(0 .6 2 1±0 .2 14 )ml (cmH2 O .kg)vs (0 .389± 0 .115 )ml (cmH2 O .kg) ;(8.9± 3.5 )gm (cm .kg)vs (5 .9± 2 .7)gm (cm .kg) ,差异有极显著性意义 ,P <0 .0 1]。结论　俯卧位可改善新生儿肺炎患儿潮气量、每分通气量和动态肺顺应性 ,降低呼吸频率和气道阻力 ,提示俯卧位是改善新生儿肺炎患儿肺功能的适宜体位。     

Echocardiographic assessment of early circulatory status in preterm infants with suspected intrauterine infection

OBJECTIVE: To assess early circulatory status in very low birthweight (VLBW) infants with suspected intrauterine infections. PATIENTS: Thirteen VLBW infants who were diagnosed with prenatal infections because of raised serum IgM at birth (infectious group), and 39 infants matched for gestational age and birth weight (control group). METHODS: Echocardiographic assessments were performed consecutively from birth to day 28 in all VLBW infants. Left ventricular output (LVO) and left ventricular stroke volume (LVSV) were measured using Doppler echocardiography. Pulsed Doppler assessment of pulmonary artery pressure (PAP) was performed using the corrected ratio of the pulmonary artery acceleration time to the right ventricular ejection time (AT/RVET(c)). Blood flow in the superior mesenteric artery (SMA) was also evaluated by Doppler ultrasound. RESULTS: Mean LVO and LVSV were both significantly higher in the infectious group than in the control group at 12 hours (LVO; 188 v 154 ml/kg/min) and 72 hours (LVO; 216 v 173 ml/kg/min) of life. Pulsed Doppler assessment of PAP showed that mean AT/RVET(c) values were significantly lower in the infectious group than in the control group at 48 hours, 96 hours, day 14, and day 28. In the analysis of SMA flow velocities, both peak systolic velocities and time averaged velocities had decreased significantly in the infectious group compared with the control group at 24 hours, 36 hours, 96 hours, and day 28. CONCLUSIONS: VLBW infants with suspected prenatal infection showed a unique circulation status, namely high cardiac output, latency of high PAP, and low organ flow.     

红霉素对哮喘豚鼠气道炎症的影响

目的：探讨红霉素对哮喘豚鼠气道炎症的影响。方法：以卵蛋白(OVA)致敏的过敏性哮喘豚鼠为模型,诱喘后24 h取支气管肺泡灌洗液(BALF)进行细胞分类及右肺中叶HE染色,镜下观察支气管肺组织形态学改变并对BALF及气道壁嗜酸粒细胞、中性粒细胞、单核细胞进行计数。结果：哮喘组BALF及支气管管壁嗜酸粒细胞、中性粒细胞、单核细胞数分别为:[B3ALF(10.9±1.2)×108/L,(3.9±0.7)×108/L,(4.2±1.0)×108/L:支气管管壁(73.6±8.8)个/HP,(7.1±1.9)个/HP,(3.5±0.7)个/HP],分别与正常对照组比较[BALF(0.5±0.1)×108/L,(0.4±0.1)×108/L,(2.0±0.4)×108/L;支气管管壁(5.5±1.6)个/HP,(1.2±0.9)个/HP,(0.7±0.5)个/HP],均显著增高(P<0.01或0.05),红霉素组BALF及支气管管壁嗜酸粒细胞、中性粒细胞、单核细胞数分别为[BALF(3.3±0.5)×108/L,(1.7±0.2)×108/L,(3.1±0.7)×108/L;支气管管壁(38.7±5.6)个/HP,(3.7±0.8)个/HP,(2.2±1.0)个/HP],较哮喘组明显下降(P<0.01或0.05),但较正常对照组仍显著增加(P<0.01或0.05)。结论：红霉素能减轻哮喘豚鼠气道炎症反应,具有抗炎作用,但红霉素不能完全阻断这种气道炎症反应。     

新生儿血清瘦素水平与生长发育关系研究

目的：探讨新生儿血清瘦素与生长发育的关系。方法：采用放射免疫法检测80例新生儿静脉血和脐血瘦素水平,其中66例足月儿分为大于胎龄儿(LGA)组18例,适于胎龄儿(AGA)组32例,小于胎龄儿(SGA)组16例。采用Rohrer’s指数=出生体重(g)×100/身长(cm)~3估测新生儿营养状态。结果：早产儿血清瘦素水平明显低于足月儿[(0.66±1.03)ng/ml vs(3.59±2.16)ng/ml],P<0.01;足月儿中AGA血清瘦素水平[(3.06±0.96)ng/ml]明显低于LGA[(4.03±2.22)ng/ml],而高于SGA[(1.13±1.98)ng/ml];足月新生儿血清瘦素水平与Rohrer’s指数、新生儿体重、胎龄呈显著正相关(r=0.61,0.68,0.62,P均<0.01)。结论：新生儿体内瘦素是反映新生儿的发育和营养状态的有用指标。[中国当代儿科杂志,2003,5(1):29-30]     

Serial Pulsed Doppler Assessment of Pulmonary Artery Pressure in Very Low Birth-Weight Infants

We assessed pulmonary artery pressure (PAP) during the early neonatal period in very low birth-weight (VLBW) infants using serial echocardiographic measurements of the ratio of the pulmonary artery acceleration time to the right ventricular ejection time corrected by heart rate [AT:RVET(c)]. Eighty-four VLBW infants weighing less than 1500 g were examined using serial color Doppler echocardiography from 3 hours to day 7 after birth. The AT:RVET(c) of infants born after 30 weeks of gestation showed a rapid, significant increase during the early neonatal period, whereas those of the groups born at less than 30 weeks showed no significant increase before day 14. At 24 hours after birth, the AT:RVET(c) values of VLBW infants did not correlate well with either the ratio of the right preejection period to the right ventricular ejection time on M-mode echocardiography or the pressure gradient between the right ventricle and the right atrium, as estimated by tricuspid regurgitation on pulsed Doppler echocardiography. The AT:RVET(c) value for the chronic lung disease (CLD) group did not differ significantly from that for the oxygen-dependent group at any assessment point. During the early neonatal period, the AT:RVET(c) of VLBW infants, as calculated by pulsed Doppler echocardiography, differed with their gestational age and did not appear to correlate well with PAP. Our data also suggest that AT:RVET(c) values may not be a good predictor of the subsequent occurrence of CLD in VLBW infants.     

肌钙蛋白Ⅰ在新生儿胎粪吸入综合征并心肌损伤诊断中的意义

目的 探讨心肌肌钙蛋白Ⅰ(CTn-Ⅰ)在新生儿胎粪吸入综合征(MAS)并心肌损伤诊断中的意义。方法：用化学发光免疫法及酶法分别测定35例合并心肌损伤的MAS患儿、30例无心肌损伤的MAS患儿及15例正常对照组血清CTn-Ⅰ及CK-MB的水平。结果：心肌损伤组生后2～3 d CTn-Ⅰ浓度为(0.67±0.13) ng/ml,较MAS对照组［(0.07±0.05) ng/ml］和正常对照组［(0.07±0.03) ng/ml］明显升高,差异有显著性意义(P<0.05)。结论：CTn-Ⅰ是诊断新生儿MAS并心肌损伤的特异性指标之一。     

Estimation of Pulmonary Arterial Pressure in the Newborn: Study of the Repeatability of Four Doppler Echocardiographic Techniques

Despite the increasing use of Doppler echocardiographic (DE) techniques to determine pulmonary arterial pressure in the neonate undergoing intensive care, there have been no studies comparing their repeatability in this population. Our objective was to compare the repeatability of four such techniques in neonates. The study was conducted in two regional neonatal units serving the North East of England. Group A (repeatability between observers): Two experienced observers performed detailed DE examinations, one directly after the other. Group B (within observer repeatability/temporal variability): One observer performed two examinations 1 hour apart. Group A comprised 15 preterm babies (26–36 weeks' gestation, 975–2915 g), most with mild respiratory failure; 4 healthy term babies; and 7 with congenital heart disease, in whom tricuspid regurgitation (TR) only was measured. Their ages were 18 hours to 12 days. Group B comprised 11 babies aged 12–64 hours with moderate to severe respiratory failure; 10 were preterm (26–36 weeks, 785–2800 g). We recorded four measurements: (1) Peak velocity of TR in m/s; (2) peak left-to-right ductal flow velocity (PDAmax in m/s); (3) TPV/RVET ratio; and (4) PEP/RVET ratio, where TPV = time to peak velocity at the pulmonary valve, PEP = right ventricular preejection period, and RVET = right ventricular ejection time. The Bland-Altman analysis was used to produce the coefficient of repeatability (CR: 95% confidence limits of repeatability), also expressed as a repeatability index (CR/mean value) and as a number of ``confidence steps'—a measure of sensitivity of the technique to hemodynamic change (range of values within the population/CR). Between-observer and within-observer repeatabilities were similar. Within-observer CR and index (%) results were for TR ± 0.26 m/s (9%); for PDAmax, ± 0.48 m/s (39%); TPV/RVET 0.1:1.0 (34%), PEP/RVET 0.12:1.00 (36%). TR and PDAmax had the largest number of confidence steps in the expected range of values (TR 8.5; PDA max 6.5; TPV/RVET 3.2; PEP/RVET 3.2). The most repeatable technique was TR, but PDAmax would also be useful for a serial study owing to the potential for large change. Systolic time interval ratios were less repeatable and likely to be less sensitive indicators of hemodynamic change.     

窒息新生儿血浆非蛋白结合铁的测定及意义

目的：探讨非蛋白结合铁在新生儿窒息后再灌注损伤中的作用。方法：用克服基体效应的Bleomycin方法，分别测定20例窒息新生儿生后6h内、6～12h和12～72h的血浆非蛋白结合铁(NPBI)，并取20例正常新生儿于出生6h内测定其血浆非蛋白结合铁作为对照。结果：窒息组NPBI阳性率明显高于 对照组(80% vs 20%)，P<0.01。窒息组血浆非蛋白结合铁水平在生后6h内为［(4.14±2.41) μmol/L］、6～12 h为(2.26±2.21) μmol/L，均比对照组［(0.28±0.79)μmol/L］显著升高(P＜0.05＝，尤以生后6 h内为最高。结论：非蛋白结合铁可能在新生儿窒息后再灌注损伤中起着重要的作用。     

Randomised controlled trial of postnatal sodium supplementation in infants of 25-30 weeks gestational age: effects on cardiopulmonary adaptation.

BACKGROUND: It has previously been shown that, in preterm babies, routine sodium supplementation from 24 hours after birth is associated with increased risk of oxygen dependency and persistent expansion of the extracellular compartment. OBJECTIVE: To explore whether this is mediated by a delayed fall in pulmonary artery pressure (PAP). Postnatal changes in PAP, estimated as the ratio of time to peak velocity to right ventricular ejection time, corrected for heart rate (TPV:RVET(c)), were compared in preterm infants who received routine sodium supplements that were either early or delayed. METHODS: Infants were randomised, stratified according to sex and gestation, to receive a sodium intake of 4 mmol/kg/day starting either from 24 hours after birth or when a weight loss of 6% of birth weight was achieved. Echocardiographic assessment was made on the day of delivery (day 0), and on days 1, 2, 7, and 14. Babies with congenital heart disease were excluded. RESULTS: There was no difference between the two groups in TPV:RVET(c) measured sequentially after birth. On within group testing, when compared with values at birth, the ratio was higher by day 3 in the early supplemented group, suggesting a more rapid fall in PAP compared with the late supplemented group, in whom a significant fall did not occur until day 14. CONCLUSIONS: The timing of sodium supplementation after preterm birth does not appear to affect the rate of fall in PAP as measured by the TPV:RVET(c) ratio. The previous observation linking routine sodium supplementation from 24 hours after birth with increased risk of continuing oxygen requirement therefore does not appear to be mediated by a delayed fall in PAP. Instead, the increased risk of continuing oxygen requirement is likely to be a direct consequence of persistent expansion of the extracellular compartment and increased pulmonary interstitial fluid, resulting from a sodium intake that exceeded sodium excretory capacity. This adds further weight to the view that clinical management, in this case the timing of routine sodium supplementation, should be individually tailored and delayed until the onset of postnatal extracellular volume contraction, marked clinically by weight loss.     

Pulmonary artery pressure: early predictor of chronic lung disease in preterm infants

AIM—To determine if pulmonary artery pressure (PAP) in ventilated preterm infants is independently associated with the development of chronic lung disease (CLD) and whether early assessment has any prognostic value.METHODS—Two cohorts (development n = 55; and validation n = 28) of preterm infants were studied at 24 hours of age. PAP was assessed non-invasively using its inverse correlation with the corrected acceleration time to right ventricular ejection time ratio (AT:RVET(c)), calculated from the pulmonary artery Doppler waveform. Clinical and respiratory variables were also collected. Using logistic regression analysis to identify factors independently associated with CLD, a prognostic score was developed to predict CLD. The ability of the score to predict CLD was described using receiver operating characteristic (ROC) curves.RESULTS—Birthweight, inspired oxygen concentration, and AT:RVET(c) were independently predictive of CLD. The area under the ROC curve was 0.96 for the development and 0.89 for the validation cohort. Exclusion of AT:RVET(c) resulted in a reduction to 0.88 and 0.73,respectively.CONCLUSION—PAP is independently associated with CLD. An early assessment of PAP using AT:RVET(c) may permit the early prediction of CLD as part of a multifactorial scoring system.     

Trials of High Frequency Jet Ventilation in Preterm Infants with Severe Respiratory Disease

ABSTRACT. Nine preterm newborn infants who were maintained on conventional mechanical ventilation for respiratory diseases were given high frequency jet ventilation in the same inspired FiO₂ for short periods (10-120 min). Lower mean airway pressures were used in high frequency jet ventilation (0.70±0.2 kPa versus 0.96±0.2 kPa in intermittent positive pressure ventilation), and peak inspiratory pressures were reduced from 2.06±0.4 to 1.38±0.24 kPa. Respiratory and haemodynamic data were compared with those obtained in intermittent positive pressure ventilation, Pa₀₂ and P_c02 were similar, while an increase in pH and reduction of central venous pressure were observed during high frequency jet ventilation. This preliminary study indicates that high frequency jet ventilation provides good ventilatory support, at least for short periods, with reduced airway pressures, and could be a promising technique for prevention of acute and chronic pulmonary barotrauma.