极早产儿俯卧位机械通气对呼吸功能的影响

目的 探讨极早产儿俯卧位机械通气对呼吸功能的影响。方法 83例经口气管插管机械通气极早产儿随机分为仰卧位组和俯卧位组,4例退出研究,79例完成治疗和观察（仰卧位组37例,俯卧位组42例）,以容量辅助/控制模式机械通气。俯卧位组患儿每仰卧位通气4 h行俯卧位通气2 h。分组干预之前以及分组干预后仰卧位组每6 h、俯卧位组每于转换为俯卧位后的1 h,分别记录呼吸机参数、动脉血气分析和生命体征。结果 俯卧位组FiO₂、气道峰压,平均气道压、机械通气时间低于仰卧位组,差异有统计学意义（P < 0.05）;两组潮气量、呼气末正压的差异无统计学意义（P > 0.05）;俯卧位组的PO₂/FiO₂比值高于仰卧位组,而氧合指数、呼吸频率较低,差异均有统计学意义（P < 0.05）。两组PaO₂、pH、BE、心率和有创动脉血压平均压的差异无统计学意义（P > 0.05）。结论 俯卧位与仰卧位交替通气能改善机械通气极早产儿的氧合功能,降低吸入氧体积分数,缩短机械通气时间。     

Disease-related response to inhaled nitric oxide in newborns with severe hypoxaemic respiratory failure

Inhaled nitric oxide (iNO) has been shown to improve oxygenation in severe persistent pulmonary hypertension of the newborn (PPHN). However, PPHN is often associated with various lung diseases. Thus, response to iNO may depend upon the aetiology of neonatal acute respiratory failure. A total of 150 (29 preterm and 121 term) newborns with PPHN were prospectively enrolled on the basis of oxygenation index (OI) higher than 30 and 40, respectively. NO dosage was stepwise increased (10–80 ppm) during conventional mechanical or high-frequency oscillatory ventilation while monitoring the oxygenation. Effective dosages ranged from 5 to 20 ppm in the responders, whereas iNO levels were unsuccessfully increased up to 80 ppm in the nonresponders. Within 30 min of iNO therapy, OI was significantly reduced in either preterm neonates (51 ± 21 vs 23 ± 17, P < .0001) or term infants with idiopathic or acute respiratory distress syndrome (45 ± 20 vs 20 ± 17, P < .0001), `idiopathic' PPHN (39 ± 14 vs 14 ± 9, P < .0001), and sepsis (55 ± 25 vs 26 ± 20, P < .0001) provided there was no associated refractory shock. Improvement in oxygenation was less significant and sustained (OI = 41 ± 16 vs 28 ± 18, P < .001) in term neonates with meconium aspiration syndrome and much less (OI = 58 ± 25 vs 46 ± 32, P < .01) in those with congenital diaphragmatic hernia. Only 21 of the 129 term newborns (16%) required extracorporeal membrane oxygenation (57% survival). Survival was significantly associated with the magnitude in the reduction in OI at 30 min of iNO therapy, a gestational age ≥34 weeks, and associated diagnosis other than congenital diaphragmatic hernia. Conclusion, iNO improves the oxygenation in most newborns with severe hypoxaemic respiratory failure including preterm neonates. However, response to iNO is disease-specific. Furthermore, iNO when combined with adequate alveolar recruitment and limited barotrauma using exogenous surfactant and HFOV may obviate the need for extracorporeal membrane oxygenation in many term infants. Received: 24 April 1997 / Accepted in revised form 3 January 1998     

Airway Pressure Release Ventilation: An Alternative Ventilation Mode for Pediatric Acute Hypoxemic Respiratory Failure

Airway pressure release ventilation (APRV) is a relatively new mode of mechanical ventilation. The use of this model of ventilation in pediatrics has been limited. The authors describe their experience with this mode of ventilation in a series of pediatric hypoxemic respiratory failure patients. Three patients with acute hypoxemic respiratory failure (AHRF) were treated with APRV, when oxygenation did not improve with pressure control ventilation (PCV). The mean age of the patients was 5.8 ± 1.3 months. Fractional oxygen concentration decreased from 0.97 ± 0.02 for PCV to 0.68 ± 0.12 for APRV, peak airway pressure fell from 36.6 ± 11.5 cm H₂O for PCV to 33.3 ± 5.7 cm H₂O for APRV, mean airway pressure increased from 17.9 ± 5.9 cmH₂O for PCV to 27 ± 2.6 cmH₂O for APRV and release tidal volume increased from 8.3 ± 1.5 mL/kg for PCV to 13.2 ± 1.1 mL/kg for APRV after 1 h. APRV may improve oxygenation in pediatric AHRF when conventional mechanical ventilation fails. The APRV modality may provide better oxygenation with lower peak airway pressure.     

Survey of sleeping position recommendations for prematurely born infants on neonatal intensive care unit discharge

Introduction Prematurely born infants are at an increased risk of sudden infant death syndrome (SIDS), particularly when sleeping prone. Parents are strongly influenced in their choice of sleeping position for their infant by practitioners. The aim of this study was to determine the neonatal units’ recommendations regarding the sleeping position for premature infants prior to and after discharge and ascertain whether there had been changes from those recorded in a survey performed in 2001–2002. Materials and methods A questionnaire survey was sent to all 229 neonatal units in the United Kingdom; 80% responded. Results and discussion The majority (83%) of units utilized the supine sleep position for infants at least 1–2 weeks prior to discharge, but after discharge, only 38% of the units actively discouraged prone sleeping and 17% additionally recommended side sleeping. Compared to the previous survey, significantly more units started infants with supine sleeping 1–2 weeks prior to discharge (p < 0.0001) and fewer recommended side sleeping after discharge (p = 0.0015). However, disappointingly, less actively discouraged prone sleeping after discharge (p = 0.0001). Conclusion Recommendations regarding sleeping position for prematurely born infants after neonatal discharge by some practitioners remain inappropriate. Evidence-based guidelines are required as these would hopefully inform all neonatal units’ recommendations.     

Effect of body position on tidal volume and minute ventilation in very low birthweight infants

Background: To progress the clinical treatment of neonates, especially in the management of respiration, we have to be able to measure their pulmonary function appropriately. Various methods have been developed, but little is known about the pulmonary function of very low birthweight infants (VLBWI) because of the difficulty in taking their measurements with existing equipment. We have developed a very low dead space pneumotachograph to measure lung function in VLBWI. Methods and results: We used our pneumotachograph on 30 infants each weighing less than 1500 g at birth. The infants were intubated with endotracheal tubes of 2.5 or 2.0 mm diameter to measure tidal volume and minute ventilation in the prone and supine position. The tidal volume in the supine position was 6.99 ± 0.42 mL/kg and 7.58 ± 0.38 mL/kg in the prone position (mean ± SE). The tidal volume was significantly larger in the prone than the supine position (P < 0.05). However, no significant difference was observed in minute ventilation and respiratory rates. Conclusion: The tidal volume significantly increased in the prone position in VBLWI, confirming the previous observation of larger healthy infants is also applicable to the very low birthweight infants.     

Ureaplasma urealyticum colonization and bronchopulmonary dysplasia: a comparative prospective multicentre study

To determine the role of tracheal colonization at birth with Ureaplasma urealyticum and other pathogenic bacteria with regard to the development of bronchopulmonary dysplasia (BPD), 97 premature infants with very low birth weight (<1500 g) were followed prospectively over 30 days in a multicentre study. Of those infants, 35 were colonized with Ureaplasma urealyticum (group Ia), 22 with other pathogenic bacteria (group Ib) and 40 infants with sterile tracheal aspirates served as controls (group II). Colonization with Ureaplasma urealyticum or with pathogenic bacteria independently increased the risk of developing BPD as compared to the controls (OR 2.55; 95% CI [1.11, 5.87]). Among Ureaplasma urealyticum and bacterial colonized infants, duration of mechanical ventilation and oxygen requirement were significantly longer than among controls (P < 0.05); during the interval of 11 to 35 days of life, every additional day of ventilation significantly increased the risk of BPD (OR 1.22; CI [1.12, 1.32]). The rate of oxygen supplementation, which was similar in both groups during the first 2 weeks of life, was significantly higher among the colonized infants at day 21 (0.38 ± 0.18 and 0.39 ± 0.16 vs 0.31 ± 0.13, P < 0.05) and at day 28 (0.38 ± 0.21 and 0.34 ± 0.15 vs 0.28 ± 0.12, P < 0.05). For infants still ventilated at age of 28 days, Ureaplasma urealyticum and bacterial colonization were associated with a significant higher risk for BPD than for uncolonized controls (OR 5.53; [1.27, 24.02]. Association of Ureaplasma urealyticum and of bacterial colonization and BPD was not weakened after adjustments were made in a multivariate analysis for other significant risk factors. Conclusion Ureaplasma urealyticum colonization is as an important risk factor in the development of bronchopulmonary dysplasia as bacterial colonization even after treatment with surfactant. Received: 23 January 1997 and in revised form: 30 December 1997 / Accepted: 5 January 1998     

Impact of new treatments for respiratory failure on outcome of infants with congenital diaphragmatic hernia

Term and near-term newborn infants with congenital diaphragmatic hernia (CDH), symptomatic in the first 24 h of life or diagnosed antenatally, without other significant malformations were treated at our hospital with high-frequency oscillatory ventilation (HFOV) as a primary modality of ventilation and elective delay in surgical repair after a period of stabilisation. When unresponsive to HFOV, infants were treated with surfactant, inhaled nitric oxide (iNO) and extracorporeal membrane oxygenation (ECMO) to achieve pre-operative stabilisation. From October 1994 to August 1998, 28 newborn infants with CDH were managed with such treatment; mean birth weight was 3184 ± 535 g and gestational age 38.5 ± 1.85 weeks. Age at operation was 68 ± 35 h. In 9 cases, large diaphragmatic defects required the use of a prosthetic patch (Gore-tex). HFOV was used for primary ventilation in inborn patients (n = 16); outborn infants (n = 12) were placed on HFOV at admittance. A total of 15 patients (53%) were stabilised using only HFOV. Bovine surfactant was administered in 12 infants and 4 responded. iNO was used in eight infants and five responded. ECMO was used in three outborn patients and one survived. Overall, out of 28 infants, 25 survived (89%). Neurological examination (Amiel-Tison and Grenier) of 15 infants showed transient anomalies at 6 months in 40% of infants, while a normal neurological examination was present in all patients at 1 year. The development quotient (Griffiths scales) was within normal values in ten and mildly abnormal in two infants tested at 1 year. Conclusion Management based on early HFOV, eventually associated with surfactant, iNO and ECMO to achieve preoperative stabilisation, resulted in a good survival rate (89%) and good neurodevelopmental outcome at 1 year of age in infants with CDH. Received: 10 November 1998 and in revised form: 3 March 1999 / Accepted: 16 March 1999     

Appropriate positive end expiratory pressure level in surfactant-treated preterm infants

Positive end expiratory pressure (PEEP) is routinely used when ventilating preterm infants, and high levels are recommended in those with severe respiratory distress syndrome (RDS). Elevation of PEEP increases lung volume, as does surfactant administration. We postulated that in surfactant-treated infants even modest PEEP levels could result in overdistension and (CO₂) retention. To test that hypothesis, lung volume, compliance and arterial blood gases were measured in eight preterm infants (median gestational age 28 weeks, range 26–35 weeks) at three PEEP levels. The infants, all with RDS, were studied at a median time of 18 h, (range 12–68 h) after their last dose of surfactant. Infants were routinely nursed at 3 cmH₂O of PEEP, the PEEP level was then raised to 6 cmH₂O or lowered to 0 cmH₂O in random order. The new setting was maintained for 20 min; the PEEP level was then changed to the third level (0 or 6 cmH₂O) again for 20 min. At the end of each 20-min period, lung volume, compliance and blood gases were measured. Lung volume was assessed by measuring functional residual capacity (FRC) using a helium dilution technique. Compliance was measured by relating the volume change from a positive pressure inflation maintained until no further volume change occurred to the pressure drop (peak inflating pressure PEEP). Increasing PEEP from 0 to 3 cmH₂O and particularly to 6 cmH₂O resulted in increases in FRC (P < 0.05), oxygenation (ns) and paCO₂ (P < 0.02). Specific compliance (compliance/FRC) (P < 0.05) and pH (P < 0.02) fell. Conclusion Following surfactant treatment, relatively low levels of positive end expiratory pressure (≤3 cmH₂O) may be appropriate. Received: 20 April 1999 / Accepted: 26 May 1999     

Cardiopulmonary interaction during partial liquid ventilation in surfactant-treated preterm lambs

Gas ventilation following instillation of perfluorochemical (PFC) liquid, partial liquid ventilation (PLV), improves gas exchange and pulmonary mechanics in neonatal animals and humans with severe respiratory distress. The effect of PLV on cardiac contractility, performance, pulmonary blood flow and ductal shunt has not been fully described. To this end, we evaluated these indices of cardiopulmonary function in eight conventionally gas ventilated, surfactant-treated premature lambs (125 days gestation) before and during PLV. Animals were instrumented with central venous and aortic lines. Serial evaluation of arterial blood chemistry/pressure, and pulmonary mechanics was performed; cardiac contractility, performance, pulmonary blood flow and ductal shunts were serially assessed by echocardiography. As compared to conventional gas ventilation, during PLV there was a significant decrease in left ventricular meridian (22.5 ± 6.6 SE vs 8.1 ± 1.4 SE g/cm², P < 0.02) and circumferential wall stress (54.1 ± 16.5 vs 24.4 ± 3.8 SE g/cm², P < 0.04) at end systole. The fall in wall stress at end systole was associated with a significant decrease in left ventricular internal diameter (1.2 ± 0.05 SE vs 1.04 ± 0.045 SE cm; P < 0.01). There were no significant changes in heart rate, systemic arterial and central venous pressures, systemic vascular resistance, left ventricular shortening and ejection fractions during PLV. The decrease in wall stress was associated with a significant decrease in mean airway pressures (15.9 ± 1.1 SE vs 9.9 ± 0.2 SE cmH₂O; P < 0.05) and ostensibly a change in intrathoracic pressures during PLV. There were no significant differences in blood flows (pre vs during PLV; ml/min/kg): pulmonary (226 ± 62 SE vs 293 ± 65 SE), aortic (237 ± 36 SE vs 204 ± 21 SE), and left to right ductal (119 ± 25 SE vs 105.5 ± 26 SE) measured before and during PLV. Conclusion Cardiac output and pulmonary blood flow do not change significantly during PLV and therefore do not appear to contribute to improved gas exchange. This stable cardiac performance occurs at lower wall stress and thereby more advantageous energetic conditions. Received: 18 July 1996 and in revised form: 28 May 1997 / Accepted: 31 May 1997     

Breathing pattern and ventilation during oral feeding in term newborn infants

The effect of oral feeding on breathing pattern and ventilation was studied in 19 healthy term neonates in the semiupright supine position. Ventilation was measured with a nasal flowmeter, and sucking pressure via a modified nipple that permitted milk delivery. The feeding pattern in these infants consisted of an initial period of continuous sucking followed by intermittent sucking for the remainder of the feed. A significant reduction in minute ventilation (P less than 0.01) was observed during continuous sucking, and resulted entirely from a reduction in breathing frequency (P less than 0.01). Tidal volume did not change (P greater than 0.05), but prolongation of expiration (P less than 0.01) and shortening of inspiration (P less than 0.05) were also observed. During intermittent sucking, the minute ventilation was similar to that of the control period. However, smaller but significant changes in breathing frequency and in duration of inspiration and expiration persisted during intermittent sucking. Our results document a significant reduction in ventilation during the initial part of oral feeding in term neonates, and subsequent recovery with continued feeding. Depending on the magnitude of this reduction in ventilation, cyanosis and bradycardia may develop in some infants during oral feeding.     

The western Canadian experience with congenital diaphragmatic hernia: perinatal factors predictive of extracorporeal membrane oxygenation and death

 This study documents how congenital diaphragmatic hernia (CDH) is managed in level III neonatal intensive care units (NICUs) in western Canada and examines perinatal factors predictive of the need for extracorporeal membrane oxygenation (ECMO). Information was obtained retrospectively from all level III NICUs in western Canada about the management of infants with CDH between 1992 and 1996; 91 infants with isolated CDH were identified. A prenatal diagnosis was made in 42 cases (46%). Surfactant was used in 53%, high-frequency oscillation (HFO) in 29%, and nitric oxide (NO) in 27%. Of the 69 infants born in referral centers, 29 (42%) were referred for possible ECMO; 17 (59%) of those required ECMO, with 65% survival. The overall requirement for ECMO was 30%. Death or ECMO occurred in 40% of cases overall. Overall survival was 82%. Survival in those needing ECMO was 74%, and in those not needing ECMO 86%. Significant predictors of death or ECMO were: prenatal diagnosis (P < 0.05), maximum postductal arterial partial pressure of oxygen (P_aO₂) <100 mmHg (P < 0.001), and an oxygenation index (OI) at 6 h >15 (P < 0.001). In cases where there is a prenatal diagnosis of CDH the mother should deliver at an ECMO center. Alternatively, an OI of >15 at 6 h and P_aO₂ < 100 mmHg should prompt referral to an ECMO center. Accepted: 19 November 1999     

Recovery of the Chronically Hypoxic Young Rabbit Heart Reperfused Following No-Flow Ischemia

The objective of this study was to test whether chronically hypoxic immature hearts exhibit greater tolerance to no-flow ischemia than normoxic hearts. Rabbits (N = 36) were raised from birth to 5 weeks of age in either hypoxic (10% O₂/90% N₂) or normoxic (room air) environment. Isolated, isovolumically beating hearts, with a fluid-filled balloon catheter in the left ventricular chamber, were perfused with a well-oxygenated buffer and studied during baseline [30 minutes; perfusion pressure, 60 mmHg; end diastolic pressure (EDP), 5 mmHg], no-flow ischemia (until onset of contracture or for 30 minutes), and Reperfusion (30 minutes; perfusion pressure, 60 mmHg). Time for onset of contracture (TOC) was defined by an increase in balloon pressure of 5 mmHg. The results were as follows: hypoxic vs normoxic: Hct, 56.4 ± 2.5* vs 36.3 ± 0.4%, (right ventricle/left ventricle) weight (dry) ratio, 0.50 ± 0.04* vs 0.28 ± 0.02. Baseline: developed pressure (ΔP), 96 ± 4 vs 93 ± 5 mmHg; coronary flow, 90 ± 10* vs 62 ± 4 ml/min/g_dry. No-flow ischemia: TOC, 12 ± 1* vs 24 ± 2 minutes. All hypoxic (no normoxic) hearts reached peak contracture. Reperfusion: Just after onset of contracture, ΔP, 80 ± 3* vs 67 ± 4 mmHg; EDP, 5 ± 1* vs 13 ± 2 mmHg; after 30 minutes of no-flow ischemia, ΔP, 58 ± 5 vs 46 ± 4 mmHg; EDP, 13 ± 1* vs 24 ± 3 mmHg; lactate release (LR), 0.15 ± 0.01 vs 0.17 ± 0.01 mmol/g_dry, creatine kinase release (CKR), 46 ± 8* vs 242 ± 28 U/g_dry. For hypoxic hearts reperfused after onset of contracture, LR was 0.11 ± 0.03 mmol/g_dry, comparable to that following 30 minutes of no-flow ischemia (*p < 0.05). Rabbit hearts subjected to hypoxia from birth developed ischemic contracture earlier and reached peak contracture, showed no significant increase in LR after onset of contracture, exhibited better recovery of EDP, and had markedly reduced CKR compared to normoxic controls.     

Survey of sleeping position recommendations for prematurely born infants

The risk of sudden infant death syndrome is increased in prematurely born infants compared to those born at term, particularly if they are either slept prone or on their side. The aim of this study was to determine whether a national campaign “Time to get back to sleep” had influenced the recommendations made by neonatal practitioners regarding the sleeping position for prematurely born babies prior to and after neonatal unit discharge. A questionnaire survey was sent to all UK neonatal units, of which 90% responded. The results were compared to those of a survey carried out prior to the national campaign. Analysis of the responses demonstrated that there was no significant difference in the proportion of units which recommended supine sleeping at least 1–2 weeks before discharge (78% versus 83%). Still, a minority of units provided written information for staff (26% versus 33%), but a greater proportion of units provided written information for parents (95% versus 90%, p = 0.047). All units recommended supine sleeping following discharge, and compared to the results of the previous survey, a smaller proportion of units additionally recommended side sleeping after discharge (8% versus 17%, p = 0.01) and a greater proportion actively discouraged prone sleeping (62% versus 38%, p < 0.0001). Conclusions: The majority but, importantly, not all neonatal units are giving appropriate recommendations regarding sleeping position following neonatal unit discharge. These results highlight that further education of neonatal staff regarding appropriate sleeping position for prematurely born babies remains imperative.     

Outcome predictors in nitric oxide treated preterm infants

Our aim was to identify factors predictive of death in preterm infants in whom inhaled nitric oxide was administered in response to poor oxygenation (oxygenation index ≥15). Of the 23 (median gestational age 28 weeks, range 24–36) infants consecutively so treated, 15 died. Non-survival was commoner in infants with air leaks (12 of 12, P < 0.002) and/or a change in their oxygenation index of less than 30% in response to inhaled nitric oxide administration (P < 0.05). Conclusion In preterm infants given inhaled nitric oxide because of poor oxygenation, a diagnosis of airleak and a lack of initial response are predictive of death. Received: 18 June 1998 / Accepted in revised form: 4 November 1998     

Total energy expenditure in infants with bronchopulmonary dysplasia is associated with respiratory status

Growth failure is a well-known problem in infants with bronchopulmonary dysplasia (BPD). We studied BPD infants' total daily energy expenditure (Ee), nutritional balance, and growth in relation to their past and current clinical status. Applying the doubly labelled water technique, Ee was measured in nine preterm infants with BPD receiving supplemental oxygen (postnatal age 61 ± 13 days) and nine matched controls (36 ± 21 days) during a 6-day period. Energy and protein balance, past and present respiratory status, and growth were assessed as well. The results show that Ee was higher in the BPD infants compared to controls (73 ± 9 vs 63 ± 8 kcal/kg/day, P < 0.05), but their faecal energy loss was lower (P < 0.01). Weight gain, energy intake, energy cost of growth, protein retention, and physical activity were not different. The respiratory frequency (RR) in the BPD infants was elevated in comparison with controls (P < 0.01). Within the BPD group, RR was positively correlated with energy expenditure (regression equation: Ee [kcal/kg/day] = 26.3 + 0.71*RR [min⁻¹]; r ² = 0.82, P < 0.001), and was the single most significant determinant of Ee. Conclusion Total energy expenditure in BPD infants is elevated and is strongly associated with their respiratory status. These findings could be of practical value for the nutritional management in infants with severe BPD. Received: 17 January 1996 / Accepted: 23 July 1996     

Respiratory hospitalizations and respiratory syncytial virus prophylaxis in special populations

Palivizumab utilization, compliance, and outcomes were examined in infants with preexisting medical diseases within the Canadian Registry Database (CARESS) to aid in developing guidelines for potential “at-risk” infants in the future. Infants who received ≥1 dose of palivizumab during the 2006–2010 respiratory syncytial virus (RSV) seasons at 29 sites were recruited and utilization, compliance, and outcomes related to respiratory infection/illness (RI) events were collected monthly. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated for premature infants ≤35 completed weeks gestational age (GA) who met standard approval criteria (group 1) compared to those with medical disorders (group 2) using Cox proportional hazards regression models with adjustment for potential confounding factors. Of 7,339 registry infants, 4,880 were in group 1 and 952 in group 2, which included those with Down syndrome (20.3%), upper airway anomalies (18.7%), pulmonary diseases (13.3%), and cystic fibrosis (12.3%). Group 2 were older at enrolment (10.2 ± 9.2 vs. 3.5 ± 3.1 months, p < 0.0005), had higher GA (35.9 ± 6.0 vs. 31.0 ± 5.4 weeks, p < 0.0005), and were less compliant with treatment intervals (69.4% vs. 72.6%, p = 0.048). A greater proportion of group 2 infants were hospitalized for RI (9.0% vs. 4.2%, p < 0.0005) and RSV (2.4% vs. 1.3%, p = 0.003) (unadjusted). Being in group 2 was associated with an increased risk of RI (HR = 2.0, 95%CI 1.5–2.5, p < 0.0005), but not RSV hospitalization (HR = 1.6, 95%CI 0.9–2.8, p = 0.106). In infants receiving palivizumab, those with underlying medical disorders, though not currently approved for prophylaxis, are at higher risk for RI events compared with preterm infants. However, risk of RSV hospitalizations is similar.     

Outcome of very low birthweight infants after introducing a new standard regime with the early use of nasal CPAP

In this paper, a retrospective study was performed to find out whether the introduction of early nasal continuous positive airway pressure (nCPAP) as a new standard regime of very low birthweight infants will lead to a decreasing tracheal intubation and ventilation rate, as well as to a lower incidence of bronchopulmonary dysplasia in a tertiary-level perinatal centre. Ninety-three infants (study group) with early nCPAP as the first respiratory support were compared to 63 infants (historical control group) born before the use of early nCPAP. No statistically significant differences were found in the baseline characteristics. The main results of the study include reduced intubation mainly in infants with a birthweight <1,000 g (study group): 58% vs. 81% (p < 0.05). The mean duration of ventilation was 248 h (control group) vs. 128 h (study group) (p < 0.001) and 437 h vs. 198 h in infants <1,000 g (p < 0.001). There was significantly reduced incidence of bronchopulmonary dysplasia from 55% to 18% for all surviving infants (p < 0.001), and for infants <1,000 g, it was 90% vs. 30% (p < 0.001). No significant differences for other outcome criteria were noted, but a significant reduction in the use of central i.v. lines, fluids, drugs, volume expansion, sedation, catecholamines, surfactant, steroids and buffer, as well as antibiotics, was observed (p < 0.05). Therefore, we can conclude that early nCPAP is an easy-to-use and safe procedure for very low birthweight infants to treat respiratory distress.     

Bone mineral density of the lumbar spine in very-low-birth-weight infants: a longitudinal study

To examine osteopenia in very low birth weight (VLBW) infants we used repeated dual-energy X-ray absorptiometry in a prospective study of lumbar spinal bone mineral density (BMD) in Japanese VLBW infants (birthweight 426–1498 g; n = 61, group 1) aged 40 weeks postconception to 3 years of age. Control subjects were Japanese infants with birthweight 1500–1999 g (group 2), 2000–2499 g (group 3), or more than 2500 g (group 4). BMD in group 1 during the early period after birth was very low, increased rapidly for 1 year, and then gradually increased until 3 years of age (r =  0.931, P < 0.0001). BMD at the age of 40 weeks postconception was 0.085 ± 0.026, 0.132 ± 0.039, 0.178 ± 0.042, and 0.196 ± 0.046 g/cm² in groups 1, 2, 3, and 4, respectively (P < 0.0001). However, at 1 and 2 years of age no differences were observed among the groups in BMD. Conclusion This study shows that lumbar spinal BMD in VLBW infants can normalize by the age of 2 years. Received: 12 May 1999 / Accepted: 11 October 1999     

Effect of inhaled nitric oxide on intrapulmonary right-to-left-shunting in two rabbit models of saline lavage induced surfactant deficiency and meconium instillation

Marked hypoxia secondary to intrapulmonary right-to-left shunting is a characteristic of respiratory failure in human neonates and can sometimes be complicated by additional extrapulmonary right-to-left shunting. To investigate the effect of inhaled nitric oxide (iNO) on intrapulmonary shunting, two typical pulmonary diseases of the newborn (respiratory distress syndrome and meconium aspiration) were reproduced in 32 mechanically ventilated rabbits weighing approximately 2 kg each. After tracheotomy, catheters were inserted into a jugular vein, a carotid artery and the right ventricle (to measure systolic right ventricular pressure [SRVP] and mixed venous oxygen content for calculation of shunt by Fick equation). Repeated airway lavages (LAV) with normal saline or repeated instillations of a suspension of human meconium (MEC) were continued until both the a/A-ratio was ≤0.14 and a peak inspiratory pressure ≥22 mbar was needed to keep the tidal volume constant at 10 ml/kg of body weight. Measurements of shunt, SRVP, systolic systemic pressure, physiological dead space, tidal volume and a ventilation index were performed before and after completion of lung damage and at 20 and 60 min after administering iNO at 80 ppm. Four groups of rabbits were studied (n = 8 in each group): LAV control and intervention, Mec control and intervention. 60 min after starting iNO, there was a decrease in shunt (LAV: 67.6% ± [SD] 11.3% vs 56.2 ± 16.4, P = 0.05; MEC: 52.6 ± 6.3 vs 44.3 ± 8.3, P < 0.05), in SRVP (LAV: 29.7 mmHg ± 10.1 mmHg vs 20.0 ± 8.2, P < 0.01; MEC: 25.1 ± 4.4 vs 22.3 ± 5.0, P = 0.46) and in dead space (% of tidal volume, LAV: 32.7% ± 10.5% vs 25.9 ± 10.1, P < 0.01; MEC: 26.1 ± 16.6 vs 18.9 ± 10.1, P = 0.05). These results demonstrate that iNO decreases intrapulmonary shunt (as well as SRVP and dead space). We suggest that iNO may be beneficial in human newborns with severe respiratory failure even if no extrapulmonary shunting via ductus or foramen ovale is apparent. Received: 18 March 1997 and revised form 6 September 1997 / Accepted: 7 September 1997     

Postnatal body weight curves for infants below 1000 g birth weight receiving early enteral and parenteral nutrition

No body weight curves are available for preterm infants <1000 g birth weight receiving early enteral and parenteral nutrition. Postnatal weight changes of 136 infants with a birth weight <1000 g were analysed retrospectively. Body weight curves for the first 30 days of life were generated for five separate birth weight groups (430–599 g, 600–699 g, 700–799 g, 800–899 g, 900–999 g). All infants had received intravenous glucose and amino acids from day 1 and intravenous lipids from day 2. Enteral feeding was started on day 1. Thus caloric intake (±SD) was advanced to 384 ± 46 kJ/kg per day (92 ± 11 kcal/kg/day) in the 1st week of life. In 136 preterm infants mean postnatal weight loss was 10.1% ± 4.6% of birth weight, birth weight was regained at a mean postnatal age of 11 ± 3.7 days, but significantly earlier (7.8 ± 3.5 days) in the lowest compared to the highest weight group. Mean subsequent weight gain was 15.7 ± 7.2 g/kg per day. This was accomplished by exclusive enteral nutrition from day 20 (median). Conclusion Our body weight curves are more adequate to evaluate growth of preterm infants than older published reference values because they are based on infants treated according to current nutritional standards. Received: 6 July 1997 and in revised form 5 October 1997 / Accepted: 15 October 1997