[No increase of incidence of retinopathy of prematurity and improvement of its outcome in a university perinatal centre level III - a prospective observational study from 1978 to 2007]. / Kein Anstieg von Inzidenz, Therapie- und Erblindungsrate der Retinopathia praematurorum in einem universitären Perinatalzentrum Level 1 - eine prospektive Beobachtungsstudie von 1978 - 2007.

BACKGROUND: There is a controversy over whether the improved survival rate of extremely low birth weight (ELBW; birth weight < 1000 g) and of extremely low gestational age (ELGA; gestational age < 28 weeks) infants has resulted in a higher incidence of severe retinopathy of prematurity (ROP) and induced blindness. We studied the incidence, treatment and the structural outcome of ROP in a Perinatal Centre Level III over a 30-year period in infants < 1500 g birth weight (VLBW = very low birth weight). PATIENTS AND METHODS: 1473 VLBW infants, who survived the first 28 days, had ocular examinations from 1978 to 2007. Neonatal and ROP data were collected prospectively. Proliferative ROP, threshold disease and high-risk prethreshold ROP indicated treatment for peripheral retinal ablation in respect to the CRYO-ROP and ETROP studies. Incidence, treatment and structural outcome of ROP were analysed for the periods 1978 - 1992 (P1) and 1993 - 2007 (P2) and for children with BW < 1000 g and > 1000 g. RESULTS: In P 1 43.1 % (n = 87) ELBW infants survived and 82.3 % (n = 372) in P 2, whereas the survival rates of the infants with a BW of 1000 - 1499 g were 74.6 % (n = 453) and 95.1 % (561), respectively. The ROP incidence was decreased from 27.6 % (n = 149) in P 1 to 15.1 % (n = 141) in P 2 significantly (p < 0.003) as well the mean BW 1136.6 ± 211.3 g to a mean BW 822.3 ± 215.3 g and the mean gestational age (GA) 29.3 ± 2.2 weeks and to a mean GA 26.4 ± 2 weeks, respectively (both differences p < 0.001). Also the coagulation rate was significantly decreased from 13 % (n = 70) in P 1 to 6.8 % (n = 63) in P 2 (p = 0.043). The blindness rates (structurally unfavourable outcome of both eyes) of 1.5 % in P 1 and 1.0 % in P 2 were not significantly reduced (p = 0.543). Among the ELBW the number of ROP infants was increased from 39 in P 1 to 117 in P 2 while the ROP incidence decreased from 44.8 % to 31.5 % (p = 0.053) and the ROP-OP rate from 19.5 % to 14.8 % (p = 0.029). Also among the ELGA the number ROP infants was increased from 66 in P 1 to 121 in P 2 but the ROP incidence was reduced from 70.2 % to 27.6 % and the ROP-OP rate from 30.9 % to 13.2 % (both p < 0.001). CONCLUSIONS: Inspite of an increase of the number of ELBW/ELGA infants and their survival rate in 1978 - 2007 there is no increase in the incidence of ROP, operations and blindness among the VLBW and VLGA infants.

The effect of surgery on lung volume and conventional monitoring parameters in ventilated newborn infants.

In newborn infants, thoraco-abdominal surgery is a serious intervention with respect to gas exchange and lung mechanics. This prospective clinical study compared surgery-induced changes in functional residual capacity (FRC) and ventilation inhomogeneity (VI) indices with changes in conventional monitoring parameters. Of 29 ventilated newborns (mean weight 2,770+/-864 g at surgery), 13, nine and seven underwent thoracic, abdominal or congenital diaphragmatic hernia (CDH) surgery, respectively. The multiple breath washout (MBWO) technique using heptafluoropropane as tracer gas (Babylog 8000; Dräger, Lübeck, Germany) was performed <6 h before surgery, 22-24 h after surgery and <6 h before extubation. Gas exchange, respiratory mechanics, FRC and VI index data were recorded. Thoraco-abdominal surgery resulted in changes to FRC and VI indices in a procedure-specific manner; however, these changes were not reflected in conventional mechanical or ventilatory monitoring parameters. FRC decreased in non-CDH infants, while FRC increased and VI indices decreased in CDH infants. Despite improvements, the differences in FRC and VI between CDH and non-CDH infants indicated persistent impaired lung function in CHD infants. MBWO can be advantageously used to measure the effect of surgery on the lung. While FRC and VI indices changed following surgery, conventional monitoring parameters did not.

Influence of bathing or washing on skin barrier function in newborns during the first four weeks of life.

BACKGROUND AND OBJECTIVES: After birth, skin barrier function is in state of flux and at risk of dysfunction. In a prospective clinical study, we compared the effects of 2 standard cleansing procedures on skin barrier function in newborns. METHODS: Fifty-seven healthy full-term neonates aged < or = 48 h were randomly assigned to either a bathing group (group B; n = 29), who were bathed with clear water twice weekly, or to a washing group (group W; n = 28), who were washed with a washcloth moistened with clear water twice weekly. Transepidermal water loss (TEWL), skin pH, stratum corneum hydration (SCH) and sebum production were measured at days 2, 7 and 28 of life on the forehead, abdomen, upper leg and buttock. RESULTS: Group B showed significantly lower TEWL on the buttock and higher SCH on the abdomen and forehead compared to group W at day 28. CONCLUSIONS: Both skin care regimens do not harm the adaptation of the skin barrier in healthy neonates within the first 4 weeks of life. Skin barrier function differentiates after birth in a regionally specific fashion.

Assessment of volume and leak measurements during CPAP using a neonatal lung model.

Although several commercial devices are available which allow tidal volume and air leak monitoring during continuous positive airway pressure (CPAP) in neonates, little is known about their measurement accuracy and about the influence of air leaks on volume measurement. The aim of this in vitro study was the validation of volume and leak measurement under CPAP using a commercial ventilatory device, taking into consideration the clinical conditions in neonatology. The measurement accuracy of the Leoni ventilator (Heinen & Löwenstein, Germany) was investigated both in a leak-free system and with leaks simulated using calibration syringes (2-10 ml, 20-100 ml) and a mechanical lung model. Open tubes of variable lengths were connected for leak simulation. Leak flow was measured with the flow-through technique. In a leak-free system the mean relative volume error +/-SD was 3.5 +/- 2.6% (2-10 ml) and 5.9 +/- 0.7% (20-60 ml), respectively. The influence of CPAP level, driving flow, respiratory rate and humidification of the breathing gas on the volume error was negligible. However, an increasing F(i)O(2) caused the measured tidal volume to increase by up to 25% (F(i)O(2) = 1.0). The relative error +/- SD of the leak measurements was -0.2 +/- 11.9%. For leaks > 19%, measured tidal volume was underestimated by more than 10%. In conclusion, the present in vitro study showed that the Leoni allowed accurate volume monitoring under CPAP conditions similar to neonates. Air leaks of up to 90% of patient flow were reliably detected. For an F(i)O(2) > 0.4 and for leaks > 19%, a numerical correction of the displayed volume should be performed.

Use of continuous positive airway pressure (CPAP) in neonatal units--a survey of current preferences and practice in Germany.

UNLABELLED: There is only limited evidence regarding the equipment or the settings (pressure and flow) at which CPAP should be applied in neonatal care. Aims of this nationwide survey of German neonatal units were to investigate (1) for which clinical indications CPAP was employed, (2) which CPAP equipment was used, (3) which CPAP settings were applied. A questionnaire on the use of CPAP was sent to all children's hospitals in Germany. Data were stratified and compared by level of medical care provided (non-academic children's hospital, academic teaching hospital and university children's hospital). 274 institutions were contacted by mailed questionnaire. The response rate was 86%, 90 non-academic children's hospitals, 119 academic teaching hospitals and 26 university children's hospitals replied. (1) There were no statistically significant difference in CPAP use between the institutions: 231 (98%) used CPAP for treating respiratory distress syndrome, 225 (96%) for treating apnoea-bradycardia-syndrome and 230 (98%) following extubation. (2) Commercial CPAP systems were employed by 71% of units, the others used a combination of different devices. Respirator generated CPAP was most commonly used. Exclusively mononasal CPAP was used by only 9%, and binasal CPAP by 55% of institutions. (3) Median CPAP was 4.5 cm H2O (range 3-7), median maximum CPAP was 7 cm H2O (range 4-10), with no statistically significant differences between the hospitals. CONCLUSION: Between units, CPAP was given via a broad range of CPAP systems and at varying pressure settings. The reported differences reflects personal experiences and preferences, rather than sound evidence from clinical trials.

The effect of changing ventilator settings on indices of ventilation inhomogeneity in small ventilated lungs.

BACKGROUND: In ventilated newborns the use of multiple breath washout (MBW) techniques for measuring both lung volume and ventilation inhomogeneity (VI) is hampered by the comparatively high dead space fraction. We studied how changes in ventilator settings affected VI indices in this particular population. METHODS: Using a computer simulation of a uniformly ventilated volume the interaction between VI indices (lung clearance index (LCI), moment ratios (M1/M0, M2/M0, AMDN1, AMDN2) of the washout curve) and tidal volume (VT), dead space (VD) and functional residual capacity (FRC) were calculated. The theoretical results were compared with measurements in 15 ventilated piglets (age <12 h, median weight 1135 g) by increasing the peak inspiratory pressure (PIP). FRC and VI indices were measured by MBW using 0.8% heptafluoropropane as tracer gas. RESULTS: The computer simulation showed that the sensitivity of most VI indices to changes in VD/VT and VT/FRC increase, in particular for VD/VT > 0.5. In piglets, the raised PIP caused a significant increase of VT from 15.4 +/- 9.5 to 21.9 +/- 14.7 (p = 0.003) and of the FRC from 31.6 +/- 14.7 mL to 35.0 +/- 15.9 mL (p = 0.006), whereas LCI (9.15 +/- 0.75 to 8.55 +/- 0.74, p = 0.019) and the moment ratios M1/M0, M2/M0 (p < 0.02) decreased significantly. No significant changes were seen in AMDN1 and AMDN2. The within-subject variability of the VI indices (coefficient of variation in brackets) was distinctly higher (LCI (9.8%), M1/M0 (6.6%), M2/M0 (14.6%), AMDN1 (9.1%), AMDN2 (16.3%)) compared to FRC measurements (5.6%). Computer simulations showed that significant changes in VI indices were exclusively caused by changes in VT and FRC and not by an improvement of the homogeneity of alveolar ventilation. CONCLUSION: In small ventilated lungs with a high dead space fraction, indices of VI may be misinterpreted if the changes in ventilator settings are not considered. Computer simulations can help to prevent this misinterpretation.

Differences in tidal breathing between infants with chronic lung diseases and healthy controls.

BACKGROUND: The diagnostic value of tidal breathing (TB) measurements in infants is controversially discussed. The aim of this study was to investigate to what extent the breathing pattern of sleeping infants with chronic lung diseases (CLD) differ from healthy controls with the same postconceptional age and to assess the predictive value of TB parameters. METHODS: In the age of 36-42 postconceptional weeks TB measurements were performed in 48 healthy newborns (median age and weight 7d, 3100 g) and 48 infants with CLD (80d, 2465 g)) using the deadspace-free flow-through technique. Once the infants had adapted to the mask and were sleeping quietly and breathing regularly, 20-60 breathing cycles were evaluated. Beside the shape of the tidal breathing flow-volume loop (TBFVL) 18 TB parameters were analyzed using ANOVA with Bonferroni correction. Receiver-operator characteristic (ROC) curves were calculated to investigate the discriminative ability of TB parameters. RESULTS: The incidence of concave expiratory limbs in CLD infants was 31% and significantly higher compared to controls (2%) (p < 0.001). Significant differences between CLD infants and controls were found in 11/18 TB parameters. The largest differences were seen in the mean (SD) inspiratory time 0.45(0.11)s vs. 0.65(0.14)s (p < 0.0001) and respiratory rate (RR) 55.4(14.2)/min vs. 39.2(8.6)/min (p < 0.0001) without statistically significant difference in the discriminative power between both time parameters. Most flow parameters were strongly correlated with RR so that there is no additional diagnostic value. No significant differences were found in the tidal volume and commonly used TB parameters describing the expiratory flow profile. CONCLUSION: The breathing pattern of CLD infants differs significantly from that of healthy controls. Concave TBFVL and an increased RR measured during quiet sleep and under standardized conditions may indicate diminished respiratory functions in CLD infants whereas most of the commonly used TB parameters are poorly predictive.

Comparison of different methods for dead space measurements in ventilated newborns using CO2-volume plot.

OBJECTIVE: The aim of the study was to test the applicability of Ventrak 1550/Capnogard 1265 (V-C) for respiratory dead space (VD) measurement and to determine anatomic (VDana), physiologic (VDphys), and alveolar dead spaces (VDalv) in ventilated neonates. DESIGN: Prospective study. SETTING: Neonatal intensive care unit. PATIENTS: 33 investigations in 22 ventilated neonates; median gestational age 34.5 weeks (range 27-41), median birthweight 2658 g (range 790-3940). METHOD: The single-breath CO2 test (SBT-CO2) and transcutaneous partial pressure of carbon dioxide (PCO2) were recorded simultaneously and VD was determined (1) automatically (V-C software), (2) by interactive analysis of the PCO2 volume plot, and (3) manually by Bohr/Enghoff equations using data obtained by V-C. RESULTS: VD measurements were possible in all cases by method 3 but not possible by methods 1 and 2 in 22 of 33 investigations (67%), especially in preterm neonates, because of disturbed signals. V.Dana/kg (1.6 +/- 0.6 ml/kg, mean +/- SD), VDana/tidal volume (VT) (0.36 +/- 0.09) were lower compared to published data in spontaneously breathing infants, whereas VDphys/kg (2.3 +/- 0.9 ml/kg) and VDphys/VT (0.50 +/- 0.12) are comparable to data obtained from the literature. Five minutes after insertion of the sensor (dead space 2.6 ml) into the ventilatory circuit, the transcutaneous PCO2 rose above baseline for 3.2% (patients > 2500 g) and 5.7% (patients < 2500 g). The time necessary for one analysis was 50-60 min. CONCLUSION: In ventilated newborns, dead space measurements were possible only in one-third by SBT-CO2, but in all cases by Bohr/Enghoff equations. Improved software could further reduce the time needed for one analysis.

Assessment of functional residual capacity using nitrogen washout and plethysmographic techniques in infants with and without bronchopulmonary dysplasia.

OBJECTIVE: In normal infants, functional residual capacity using plethysmography (FRCpleth) exceeds FRC(N2) (using nitrogen washout) and the within-subject difference FRC(pleth-N2) indicates the part of pulmonary gas volume not ventilated during tidal breathing. We postulated that infants with bronchopulmonary dysplasia (BPD) have an elevated FRC(pleth-N2). DESIGN: In a prospective study, FRC(pleth-N2) in healthy newborns (controls n = 17) was compared to that in neonates recovering from the respiratory distress syndrome without BPD (noBPD, studied at discharge, n = 13) and with BPD (BPD1 n = 14, studied at 36 post-conceptional weeks; BPD2 n = 16, at discharge). MEASUREMENTS AND RESULTS: Paired measurements, FRCpleth and FRC(N2), were performed using a plethysmograph (Jaeger, Germany) and an open-circuit nitrogen washout technique (SensorMedics 2600, USA). In comparison to the controls (5.2 ml/kg), FRC(pleth-N2)/kg in noBPD (12.7 ml/kg, p < 0.001), in BPD1 (24.9 ml/kg, p < 0.001) and in BPD2 (13.5 ml/kg, p < 0.001) was significantly higher. Compared with that of the controls FRCpleth was significantly increased in BPD1 (p < 0.001) and FRC(N2) was decreased in noBPD and both BPD groups. CONCLUSION: The FRC(pleth-N2) is a reliable indicator for pulmonary inhomogeneities in infants with respiratory diseases.

Leak measurements in spontaneously breathing premature newborns by using the flow-through technique.

A new method for measuring and correcting air leaks during lung-function testing in infants has been validated in vitro and in vivo by using a flow-through system that measured the inflow and outflow of a face mask. An adjustable leak was quantified by using suction flow to validate the accuracy of leak measurements. To validate the leak correction, the volume of a pump was measured with different air leaks (0-30%). The method developed was tested in 67 infants breathing spontaneously. There was good agreement between measured and simulated leaks (r = 0.998, P < 0.001; 95% limits of agreement were -0.3 and 0.1%, respectively). The volume was generally underestimated because of leaks, and the volume error was up to 94% compared with the maximum error of 5% after leak correction. With continuous leak measurements in vivo, there were <4% actual leaks (median 2.6%), and we did not observe any leaks in >7% of cases. The leak correction improved the accuracy of ventilatory measurements. The monitoring of leaks is helpful for airtight placement of the face mask and for prevention of serious measurement errors caused by leaks.

Changes in pulmonary function in preterm infants recovering from RDS following early treatment with ambroxol: results of a randomized trial.

Several studies have demonstrated that ambroxol stimulates surfactant synthesis and has antioxidative and antiinflammatory effects. We investigated the effect of ambroxol on lung function in newborns with respiratory distress syndrome (RDS) weighing <1,500 g. In all, 102 newborns were enrolled (52 received ambroxol and 50 placebo). After extubation, lung function tests were performed weekly using a face mask for ventilatory measurements and a catheter tip pressure transducer (diameter 1.7 mm) for esophageal pressure measurements (Pes) The flow-through technique was used to eliminate apparatus dead space and to allow long-term measurements during quiet sleep. Percentile curves of pulmonary function parameters from healthy newborns were used for comparison. During the first 28 days, 42 newborns were extubated in the ambroxol group and 36 in the placebo group. The ventilatory parameters of both treatment groups were in the normal range and there were no significant differences between the two groups at any time. After extubation, the ratio of tidal volume to maximal esophageal pressure changes (V(T)/P(es,max)) was below the 10th percentile in the ambroxol and placebo-treated groups. In the ambroxol group the 10th percentile was reached on day 10, whereas in the placebo group the 10th percentile was reached significantly later (P < 0.05) on day 23. Modeling of power expenditures was used to identify the optimal breathing pattern so that small differences in ventilatory parameters between the two groups could be analyzed. We conclude that early ambroxol treatment has only a modest effect on lung function in newborns with established RDS. The sensitivity of tidal breathing parameters is not sufficient to detect these small changes in lung mechanics, but small improvements could be demonstrated in lung mechanics 10 days after extubation in the ambroxol-treated group.

Right-sided pulmonary aplasia: longitudinal lung function studies in two cases and comparison to results from term healthy neonates.

Agenesis of the right lung was diagnosed prenatally in two neonates born at 36 and 37 weeks, respectively. Computed tomographic scans and magnetic resonance imaging indicated that both cases had a Type 2 pulmonary agenesis, which was confirmed later by bronchoscopy. Both patients were clinically stable during the neonatal period. Serial pulmonary function tests revealed a decrease in specific respiratory system compliance (sCrs) in both neonates and a marked discrepancy between functional residual capacity measured by the nitrogen washout technique (FRCN2) and by plethysmography (FRCpleth) on follow-up. Early decrease of respiratory system compliance (Crs) and increase of respiratory system resistance (Rrs) in one infant preceded the onset of tracheal stenosis, which remained asymptomatic until the age of 8 weeks, when the infant developed acute respiratory failure requiring intubation and mechanical ventilation with high airway pressures. Aortopexy, implantation of a tissue expander into the right hemithorax, and laser ablation of fibrotic tissue at the site of tracheal stenosis were performed to achieve successful extubation. The second infant remained asymptomatic. Values for lung mechanics and volumes for both infants with pulmonary aplasia were as follows: Crs, 3.43 and 10.60 mL x kP(-1) x kg(-1); sCrs, 0.23 and 1.28 kpa(-1); Rrs, 11.1 and 7.4 kpa x s x L(-1); FRCN2, 14.9 and 10.2 mL x kg(-1); FRCpleth, 28.2 and 25.8 mL x kg(-1); FRCN2: FRCpleth ratio, 0.56 and 0.54 for patients 1 and 2, respectively. These values differed considerably from results of a control group of nine term healthy neonates (Crs, 10.0+/-1.8 mL x kPa(-1) x kg(-1); sCrs, 0.43+/-0.08 kpa(-1); Rrs, 5.10+/-0.55 kpa x s x L(-1); FRCN2, 24.0+/-2.5 mL x kg(-1); FRCpleth, 31.1+/-6.0 mL x kg(-1); FRCN2:FRCpleth ratio, 0.78+/-0.10). In conclusion, serial assessment of lung mechanics and pulmonary gas volumes detects airway obstruction early in neonates with unilateral lung agenesis. Bronchoscopy is recommended. Along with conventional surgical procedures, an expandable implant may improve management or prevent respiratory failure in selected cases.

Effect of early ambroxol treatment on lung functions in mechanically ventilated preterm newborns who subsequently developed a bronchopulmonary dysplasia (BPD).

In a randomized trial in 102 preterm newborns with respiratory distress syndrome (RDS) it has been shown that early Ambroxol treatment (30 mg kg(-1) over the first 5 days) significantly reduces the incidence of RDS-associated complications [bronchopulmonary dysplasia (BPD), intraventricular haemorrhage, post-natal acquired pneumonia]. The aim of the present analysis was to investigate the effect of Ambroxol treatment on lung function in newborns who developed BPD. Respiratory function testing (RFT) was performed immediately after extubation and at day 28. Tidal volume (VT) and respiratory frequency (f) were measured during tidal breathing using the deadspace free flow-through technique. The lung mechanic parameter VT/maxPes was determined by measuring the maximal oesophageal pressure changes, maxPes, with a catheter tip pressure transducer. In the placebo group 36/50 infants were extubated within the first 28 days of life and 13/36 (36%) developed BPD. In the Ambroxol group 44/52 were extubated and 9/44 (20%) developed BPD. After extubation, RFT showed (i) no statistically significant difference in the ventilatory parameters of either treatment group, (ii) improved (P<0.05) lung mechanics (VT/maxPes) in Ambroxol group compared to controls (94+/-27 ml kPa(-1) vs. 8.1+/-2.6 ml kPa(-1)) and (iii) no statistically significant difference in lung function between infants with and without BPD. At day 28 we found (i) no effect of early Ambroxol treatment on lung functions, (ii) significantly (P < 0.05) higher f (58.5+/-11.7 min(-1) vs. 49.7+/-10.1 min(-1)) and significantly (P<0.01) lower V(T) (9.6+/-1.9 ml vs. 12.3+/-2.7 ml) and V(T)/maxPes (8.9+/-2.6 ml kPa(-1)] vs. 12.0+/-2.9 ml kPa(-1)) in infants with BPD compared to infants without and (iii) these differences are not influenced by early Ambroxol treatment. If the process of BPD development is induced, early Ambroxol treatment has no influence on impaired lung function at day 28.

2nd European symposium on liquid ventilation.

After the successful meeting in Berlin, advances and research results in the understanding of liquid ventilation has been performed. About 80 applied and basic scientists met in the 1st European Symposium, from clinicians (pediatricians, neonatologists, intensivists, etc.) to other basic scientists (physiologists, biologists, bioengineerings, etc.). Furthermore, we also invited representatives of pharmaceutic industry interested in this hot topic. Our main goal is to provide an opportunity for all liquid researchers in this field to meet together and with the top scientists of Liquid Ventilation Research. We planned to provide both a scientific and a friendly atmosphere to enhance the exchange of experiences and to facilitate future plans. We hope this 2nd European Symposium will be a continuation point for collaboration of groups in Europe, to study all research aspects of the technique to carry on future trials. There are still a lot of unanswered questions to be solved. Among the unsolved issues and practical questions we would like to point out the following items: 1. Perfluorocarbon: which product to use and how to deliver it. 2. Perfluorocarbon interactions in the lung. 3. Perfluorocarbon. Toxicity and cytoprotection. 4. Partial Liquid Ventilation: ventilatory strategies from delivering to weaning. 5. Impact of Partial Liquid Ventilation Experimental and clinical aspects. 6. General discussion and plan for the future. We know that none of these questions can be completely answered now, but hope collaboration and communication will bring us closer to achieve these goals. Moreover, concerted actions should be started to search for research grant founding. For all those reasons we would like to thank all active and passive participants, who came to Bilbao to present, discuss and foster future work in Liquid Ventilation.

Surfactant protein SP-B counteracts inhibition of pulmonary surfactant by serum proteins.

In addition to the primary surfactant deficiency in newborns with respiratory distress syndrome (RDS), in the later course of RDS substantial protein leakage into the alveolar spaces can occur by damage to the alveolocapillary membrane. Acute lung injury results in surfactant dysfunction due in part to inhibition by serum proteins. The aim of this study was to investigate the influence of SP-B on the inhibitory effects of albumin (alb) and fibrinogen (fib) on the surface activity of pulmonary surfactant, using a) surface tension measurement with the pulsating bubble surfactometer in suspensions and b) in surfactant films applying the hypophase exchanger. After hypophase exchange a preformed film of Survanta is very resistant to the inhibitory activity of alb or fib. The surface tensions of suspensions are significantly higher (p <0.001) than the surface tensions of preformed surfactant films if alb or fib were added, e.g., 42 (41 to 43) mN/m vs. 21 (19 to 22) mN/m for Survanta with 20 mg alb/ml. After additional supplementation of Survanta with SP-B the surface activity of Survanta/1% SP-B films did not show inhibition by fib (2 mg/ml), (surface tension 8 (4 to 13) mN/m). These results indicate that SP-B can play an important role to protect the pulmonary surfactant film from inactivation by serum proteins.

[Effect of background flow on the accuracy of respiratory flow and respiratory volume measurement in newborn infants]. / Einfluss eines Hintergrundflows auf die Genauigkeit der Atemflow- und Atemvolumenmessung bei Neugeborenen.

Measurement of ventilation, in particular in preterm infants, is greatly impaired by equipment dead space, with its significant effect on the ventilatory pattern and gas exchange. For patients of this age, therefore, dead-spacefree methods are needed for long-term measurements. Rebreathing can be avoided if the pneumotachograph (PNT) and face mask are flushed with a continuous background flow. The effect of this on the measurements has not yet been investigated in detail. A measuring system comprising two identical baby PNTs (Jaeger/Germany) permitting a background flow of between 0 and 7 l per min was used. Spontaneous breathing was simulated with a 100 ml calibration syringe employing volumes of 20, 40, 60 and 100 ml (Rudolph/USA) and a frequency of 30 min-1. The measurements were carried out with a T-piece from a respirator circuit, a hand mask (50 ml) and a face chamber having a volume of 850 ml (Siemens-Elema/Sweden). To investigate the dynamic properties of the equipment, we employed flow jumps generated with a magnetic valve (response time < 2 ms) and analysed the responses using Fourier analysis. We were unable to find any significant relationship between the accuracy of volume measurement and tidal volume for any of the measured volumes. An increase in background flow resulted in an underestimation of the volume with an error < 3%. We found no influence of the background flow or type of face mask on the frequency response.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effect of physical properties of respiratory gas on pneumotachographic measurement of ventilation in newborn infants]. / Einfluss der physikalischen Eigenschaften des Atemgases auf die pneumotachographische Ventilationsmessung bei Neugeborenen.

UNLABELLED: The measurement of ventilation in neonates has a number of specific characteristics; in contrast to lung function testing in adults, the inspiratory gas for neonates is often conditioned. In pneumotachographs (PNT) based on Hagen-Poiseuille's law, changes in physical characteristics of respiratory gas (temperature, humidity, pressure and oxygen fraction [FiO2]) produce a volume change as calculated with the ideal gas equation p*V/T = const; in addition, the viscosity of the gas is also changed, thus leading to measuring errors. In clinical practice, the effect of viscosity on volume measurement is often ignored. The accuracy of these empirical laws was investigated in a size 0 Fleisch-PNT using a flow-through technique and variously processed respiratory gas. Spontaneous breathing was simulated with the aid of a calibration syringe (20 ml) and a rate of 30 min-1. RESULTS: The largest change in viscosity (11.6% at 22 degrees C and dry gas) is found with an increase in FiO2 (21...100%). A rise in temperature from 24 to 35 degrees C (dry air) produced an increase in viscosity of 5.2%. An increase of humidity (0...90%, 35 degrees C) decreased the viscosity by 3%. A partial compensation of these viscosity errors is thus possible. Pressure change (0...50 mbar, under ambient conditions) caused no measurable viscosity error. With the exception of temperature, the measurements have shown good agreement between the measured volume measuring errors and those calculated from viscosity changes. CONCLUSIONS: If the respiratory gas differs from ambient air (e.g. elevated FiO2) or if the PNT is calibrated under BTPS conditions, changes in viscosity must not be neglected when performing accurate ventilation measurements. On the basis of the well-known physical laws of Dalton, Thiesen and Sutherland, a numerical correction of adequate accuracy is possible.

[Measuring equipment for bedside diagnosis of respiratory function in spontaneously breathing newborn infants]. / Messplatz zur bettseitigen Atemfunktionsdiagnostik bei spontanatmenden Neugeborenen.

Equipment was developed for bedside lung function testing in the newborn using the simultaneous measurement of air flow rate, tidal volume, and esophageal pressure changes as a measure of transpulmonary pressure. The equipment has a number of advantages for the investigation of very low birthweight infants. A flow-through technique was used to eliminate the dead space of the face mask and a very thin micro-tipped catheter permits ready measurement of esophageal pressure. With this equipment, long-term measurements are also possible in oxygen-dependent newborns and the air-tightness of the mask can be monitored continuously. Long-time measurements in neonates are a prerequisite for standardizing the measuring conditions and adapting the duration of the measurement to the variability of the signals, especially in newborn with an irregular pattern of breathing.

Positive effects of early continuous positive airway pressure on pulmonary function in extremely premature infants: results of a subgroup analysis of the COIN trial.

OBJECTIVE: Early continuous positive airway pressure (CPAP) may reduce lung injury in preterm infants. PATIENTS AND METHODS: Spontaneously breathing preterm infants were randomised immediately after birth to nasal CPAP or intubation, surfactant treatment and mechanical ventilation. Pulmonary function tests approximately 8 weeks post-term determined tidal breathing parameters, respiratory mechanics and functional residual capacity (FRC). RESULTS: Seventeen infants received CPAP and 22 mechanical ventilation. Infants with early CPAP had less mechanical ventilation (4 vs 7.5 days; p=0.004) and less total respiratory support (30 vs 47 days; p=0.017). Post-term the CPAP group had lower respiratory rate (41 vs 48/min; p=0.007), lower minute ventilation (223 vs 265 ml/min/kg; p=0.009), better respiratory compliance (0.99 vs 0.82 ml/cm H(2)O/kg; p=0.008) and improved elastic work of breathing (p=0.004). No differences in FRC were found. CONCLUSIONS: Early CPAP is feasible, shortens the duration of respiratory support and results in improved lung mechanics and decreased work of breathing.