Hans Proquitté

Manual ventilation devices in neonatal resuscitation: Tidal volume and positive pressure-provision

BACKGROUND Excessive peak inspiratory pressures (PIP) and high tidal volumes (Vt) during manual ventilation can be detrimental to the neonatal lung. We compared the influence of different manual ventilation devices and individual professional experience on the extent of applied Vt and PIP in simulated neonatal resuscitation. MATERIAL AND METHODS One hundred and twenty medical professionals were studied. An intubated mannequin (equivalent to 1.0 kg neonate) was ventilated using two different devices: a self-inflating bag and a T-piece resuscitator. Target value was a PIP of 20 cm H(2)O. Applied PIP and the resulting Vt were recorded continuously using a respiratory function monitor (CO(2)SMO(+), Novametrix, USA). RESULTS Vt and PIP provision was significantly higher in SI-bags, compared to T-piece devices: median (interquartile range) PIP 25.6 (18.2) cm H(2)O vs 19.7 (3.2) cm H(2)O (p<0.0005), and Vt 5.1(3.2) ml vs Vt 3.6 (0.8) ml (p<0.0005) respectively. The intersubject variability of Vt and PIP provision was distinctly higher in SI-bags, compared to T-piece devices. Professional experience had no significant impact on the level and the variability of Vt or PIP provided. CONCLUSION Use of T-piece devices guarantees reliable and constant Vt and PIP provision, irrespective of individual, operator dependent variables. Methods to measure and to avoid excessive tidal volumes in neonatal resuscitation need to be developed.

DELIVERY ROOM MANAGEMENT OF VERY LOW BIRTH WEIGHT INFANTS IN GERMANY, AUSTRIA AND SWITZERLAND ― A COMPARISON OF PROTOCOLS

BackgroundSurveys from the USA, Australia and Spain have shown significant inter-institutional variation in delivery room (DR) management of very low birth weight infants (VLBWI, < 1500 g) at birth, despite regularly updated international guidelines.ObjectiveTo investigate protocols for DR management of VLBWI in Germany, Austria and Switzerland and to compare these with the 2005 ILCOR guidelines.MethodsDR management protocols were surveyed in a prospective, questionnaire-based survey in 2008. Results were compared between countries and between academic and non-academic units. Protocols were compared to the 2005 ILCOR guidelines.ResultsIn total, 190/249 units (76%) replied. Protocols for DR management existed in 94% of units. Statistically significant differences between countries were found regarding provision of 24 hr in house neonatal service; presence of a designated resuscitation area; devices for respiratory support; use of pressure-controlled manual ventilation devices; volume control by respirator; and dosage of Surfactant. There were no statistically significant differences regarding application and monitoring of supplementary oxygen, or targeted saturation levels, or for the use of sustained inflations. Comparison of academic and non-academic hospitals showed no significant differences, apart from the targeted saturation levels (SpO2) at 10 min. of life. Comparison with ILCOR guidelines showed good adherence to the 2005 recommendations.SummaryDelivery room management in German, Austrian and Swiss neonatal units was commonly based on written protocols. Only minor differences were found regarding the DR setup, devices used and the targeted ranges for SpO2 and FiO2. DR management was in good accordance with 2005 ILCOR guidelines, some units already incorporated evidence beyond the ILCOR statement into their routine practice.

Three-Dimensional Multi-Slice View New Prospects for Evaluation of Congenital Anomalies in the Fetus

Objectives. The purpose of this study was to describe the use and potential of Multi‐Slice View 3‐dimensional (3D) ultrasonographic software (Medison Co, Ltd, Seoul, Korea) in showing fetal congenital anomalies. Methods. Fetuses with congenital anomalies diagnosed by means of 2‐dimensional ultrasonography were prospectively included in the study. Good‐quality 3D volumes of the region of interest were obtained in each case. Subsequently, these volumes were reviewed with use of 3D eXtended Imaging with Multi‐Slice View and SonoMR (Medison Co, Ltd). Image processing was performed through the use of off‐line software (Medison XI Viewer, version 1.0.0.218). Results. A total of 6 fetuses (median gestational age, 27 weeks; range, 16–35 weeks) with the following anomalies were examined: dacryocystocele, esophageal atresia, right‐sided aortic arch, hydrometrocolpos, horseshoe kidney, and hemivertebra. Images of diagnostic quality were obtained from all patients. According to the respective underlying anomalies and the positions of the fetuses, images were obtained from the initial axial plane in 2 cases (esophageal atresia and right‐sided aortic arch) and from reconstructed planes in the remaining 4 cases (dacryocystocele, hydrometrocolpos, horseshoe kidney, and hemivertebra). Conclusions. Three‐dimensional Multi‐Slice View can deliver informative images of the region of interest regardless of fetal position. It may be particularly helpful for evaluation of difficult anomalies in the fetus.

Current limitations of volumetric capnography in surfactant-depleted small lungs.

Objective To investigate the suitability of volumetric capnography for assessing alveolar gas exchange in very small, surfactant-depleted lungs. Design Prospective animal trial. Settings Animal laboratory in a university setting. Subjects Twenty-one ventilated newborn piglets (age <12 hrs; median weight, 890 g; range, 560–1435 g). Interventions Bronchoalveolar lavage with instillation of 30 mL/kg normal saline. Ventilatory, circulatory, and lung mechanic variables were measured before and 0, 30, and 60 mins after bronchoalveolar lavage. Measurements and Main Results The alveolar deadspace fraction calculated by the Bohr and the Bohr/Enghoff equations increased three-fold (p < .001) after bronchoalveolar lavage in capnograms with distinct alveolar plateau, whereas in capnograms without alveolar plateau no statistical significant difference was seen. The main problem of capnography in small and especially stiff lungs was the high number of discarded records exclusively caused by a missing alveolar plateau. Rates of discarded records of capnography were 9.5% before lavage and increased (p < .01) to 52.4%, 47.6%, and 42.8% after bronchoalveolar lavage (0, 30, and 60 mins). With decreasing exhalation time, the number of discarded records increased significantly. No plateau was seen in >75% of recorded files with exhalation times <200 msecs. The effect of bronchoalveolar lavage on all variables measured was quite different, with the highest impact on required ventilatory settings, calculated oxygenation variables, and compliance. The effect of bronchoalveolar lavage on arterio-alveolar CO2 difference, CO2 production, and alveolar deadspace was much lower and statistically significant only in capnograms with alveolar plateau. Conclusions Volumetric capnography is a useful tool to detect impaired alveolar gas exchange in surfactant-depleted small lungs. However, the method failed if there was no alveolar plateau in the volumetric capnogram especially in stiff lungs with short exhalation times.

Comparison of different techniques to measure air leaks during CPAP treatment in neonates

UNLABELLED Continuous positive airway pressure (CPAP) is routinely used for respiratory support in neonates. Air leaks are not uncommon and can hinder treatment. This study compared leak flow data obtained using different leak definitions through modeling and in vitro measurements. METHODS Using a computer simulation of an ideal CPAP system, the relationship between leak flow and three leak definitions was investigated. The leak flow was based on the measured inspiratory, expiratory and averaged breathing flow as commonly used in neonates. The theoretical results were compared with in vitro measurements using a commercial CPAP device for neonates (Leoni, Heinen & Löwenstein, Germany). Spontaneous breathing was simulated using a mechanical lung model, and defined air leaks were simulated using open silicone tubes of different lengths. RESULTS Computer simulations showed that leak calculations were affected by leak flow and breathing pattern, and that the relationships were mostly non-linear. There were large differences in the results between the three leak definitions. The in vitro measurements correlated strongly with the theoretical modeling results. The derived numerical volume correction reduced the leak-dependent volume error in the mean (S.D.) to -1.6 (4.6)%. CONCLUSION It is difficult to compare different measuring conditions and different CPAP devices due to the variation in results depending on the leak definition and the breathing pattern. Leak flow displays would provide superior air leak monitoring.

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

BackgroundIn 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.MethodsUsing 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.ResultsThe 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.ConclusionIn 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.

Tracheal tube airleak in clinical practice and impact on tidal volume measurement in ventilated neonates.

Objective: To determine the prevalence, size, and factors affecting tracheal tube (TT) leak in clinical practice and their influence on the displayed tidal volume (Vt) in ventilated newborn infants using uncuffed TTs. Monitoring of Vt is important for implementation of lung-protective ventilation strategies but becomes meaningless in the presence of large TT airleaks. Design: Retrospective clinical study. Setting: Neonatal intensive care unit. Patients: Patient records of 163 neonates ventilated with Babylog 8000 for ≥5 hrs with a median (range) gestation age of 31.1 wks (23.3–41.9 wks) and a median birth weight of 1470 g (410–4475 g) were evaluated. Interventions: Ventilatory settings, TT leak, and Vt were recorded every 3 hrs. The lowest, median, and highest TT leaks were noted on the day the first TT leak (>5%) occurred, the day on which TT leak peaked, and the day of extubation. Measurements and Main Results: A TT leak of >5% was seen in 122 (75%) infants. Neonates with TT leak, compared with those without TT leak, had a longer duration of mechanical ventilation (p < .001), a lower gestational age (p = .004), a reduced birth weight (p = .005), and a higher prevalence of reintubation (p = .003). The greatest TT leak was seen in infants ventilated with a TT of <3-mm diameter. During the entire duration of mechanical ventilation, 42.3% of all neonates experienced at least one TT leak of >40% commonly seen on the third day of mechanical ventilation. Regression analysis showed that a TT leak of 40% indicated that the displayed Vt was underestimated by 1.2 mL/kg (about 24% of target Vt). Conclusions: TT leak is highly variable, and TT leak of >40% with clinically relevant Vt errors occurred in nearly half of all ventilated neonates. Preterm infants of low birth weight and with small-diameter TTs ventilated for a long period were at greater risk of TT leak.

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 H2O/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.

Weaning of neonates from mechanical ventilation by use of nasopharyngeal high-frequency oscillatory ventilation: a preliminary study

Abstract Objective. To investigate the feasibility of nasopharyngeal high-frequency oscillatory ventilation (nHFOV) immediately after extubation in difficult-to-wean preterm infants. Study design. This was an observational study of 20 mechanically ventilated neonates [median (range) birth weight 635 (382–1020)g, median gestational age 25.3 (23.7–27.6) weeks] at high risk for extubation failure. Nine infants had failed at least one previous extubation. Fourteen infants were given hydrocortisone. All 20 infants were extubated into nHFOV, with a mean airway pressure of 8 cmH2O, an amplitude of 20 cmH2O, and a frequency of 10 Hz. Results. Infants remained on nHFOV for a median duration of 136.5 (7.0–456.0) h until further weaning to continuous positive airway pressure (n =14) or reintubation (n = 6). Reintubation was performed in 1 of 11 infants who had not experienced any previous extubation, and in five of nine infants who had experienced at least one previous extubation (P < 0.05). PaCO2 was virtually unchanged from preextubation levels 2 h after extubation, but declined significantly at 32 h from 59.8 (45.0–92.3) mmHg to 50.7 (39.8–74.4) mmHg (P < 0.01). PaCO2 returned to preextubation levels upon discontinuation of nHFOV. Conclusion.This small observational study demonstrates that nHFOV can be successfully applied to wean premature infants from ventilator support.

Three-dimensional ultrasonographic reslicing of the fetal brain to assist prenatal diagnosis of central nervous system anomalies

Objectives. The purpose of this study was to evaluate the potential of 3‐dimensional ultrasonographic planar and nonplanar reslicing techniques. Methods. Fetuses with severe brain anomalies diagnosed by means of 2‐dimensional ultrasonography were prospectively included in the study. Good‐quality 3‐dimensional volumes of the fetal head were obtained in each case. Subsequently, these volumes were reviewed with use of 3‐dimensional extended imaging with Oblique View and DynamicMR (Medison Co, Ltd, Seoul, Korea). Results. Eight fetuses (mean gestational age, 23 weeks; range, 20–30 weeks) with the following central nervous system anomalies were examined: semilobar holoprosencephaly, absent cavum septum pellucidum, porencephaly in twin‐to‐twin transfusion syndrome, partial agenesis of the corpus callosum, Dandy‐Walker variant, open‐lip schizencephaly, aneurysm of the vein of Galen, and dilated cavum vergae. Conclusions. Planar and nonplanar reslicing of the volumes delivered informative images in any reconstructed plane. One important prerequisite, however, was the absence of acoustic shadowing during data acquisition.