The effect of automated oxygen control on clinical outcomes in preterm infants: a pre- and post-implementation cohort study.

Several studies demonstrated an increase in time spent within target range when automated oxygen control (AOC) is used. However the effect on clinical outcome remains unclear. We compared clinical outcomes of preterm infants born before and after implementation of AOC as standard of care. In a retrospective pre-post implementation cohort study of outcomes for infants of 24-29 weeks gestational age receiving respiratory support before (2012-2015) and after (2015-2018) implementation of AOC as standard of care were compared. Outcomes of interest were mortality and complications of prematurity, number of ventilation days, and length of stay in the Neonatal Intensive Care Unit (NICU). A total of 588 infants were included (293 pre- vs 295 in the post-implementation cohort), with similar gestational age (27.8 weeks pre- vs 27.6 weeks post-implementation), birth weight (1033 grams vs 1035 grams) and other baseline characteristics. Mortality and rate of prematurity complications were not different between the groups. Length of stay in NICU was not different, but duration of invasive ventilation was shorter in infants who received AOC (6.4 ± 10.1 vs 4.7 ± 8.3, p = 0.029).Conclusion: In this pre-post comparison, the implementation of AOC did not lead to a change in mortality or morbidity during admission. What is Known: • Prolonged and intermittent oxygen saturation deviations are associated with mortality and prematurity-related morbidities. • Automated oxygen controllers can increase the time spent within oxygen saturation target range. What is New: • Implementation of automated oxygen control as standard of care did not lead to a change in mortality or morbidity during admission. • In the period after implementation of automated oxygen control, there was a shift toward more non-invasive ventilation.

Assessment of validity and predictability of the FiO2-SpO2 transfer-function in preterm infants.

In this paper an investigation of the gain, delay, and time-constant parameters of the transfer function describing the relation between fraction of inspired oxygen (FiO2) and oxygen saturation in the blood (SpO2) in preterm infants is presented. The parameters were estimated following FiO2 adjustments and goodness of fit was used to assess the validity of the model when using an assumed first-order transfer function. For responses identified to be first-order, the estimated parameters were then clustered to identify areas where they tended to be concentrated. Each group described an operating region of the transfer function; thus, predicting the right operating region could potentially assist a range-based robust inspired oxygen controller to provide more optimal control by adapting itself to different clusters. Accordingly, the samples were assigned labels based on their cluster associations and 14 features available at the time of each adjustment were used as inputs to an artificial neural network to classify the clustered samples. The validity study suggested that 37% of the adjustments were followed by first-order responses. Prediction studies on the first-order responses indicated that the clusters could be predicted with an average accuracy of 64% when the parameters were divided into two groups.

Regional respiratory inflation and deflation pressure-volume curves determined by electrical impedance tomography.

Measurement of regional lung volume changes during a quasi-static pressure-volume (PV) manoeuvre using electrical impedance tomography (EIT) could be used to assess regional respiratory system mechanics and to determine optimal ventilator settings in individual patients. Using this approach, we studied regional respiratory system mechanics in healthy and lung-injured animals, before and after surfactant administration during inflation and deflation PV manoeuvres. The comparison of the EIT-derived regional PV curves in ventral, middle and dorsal regions of the right and left lungs showed not only different amounts of hysteresis in these regions but also marked differences among different landmark pressures calculated on the inflation and deflation limbs of the curves. Regional pressures at maximum compliance as well as the lower and upper pressures of maximum compliance change differed between the inflation and deflation and increased from ventral to dorsal regions in all lung conditions. All these pressure values increased in the injured and decreased in the surfactant treated lungs. Examination of regional respiratory system mechanics using EIT enables the assessment of spatial and temporal heterogeneities in the ventilation distribution. Characteristic landmarks on the inflation and especially on the deflation limb of regional PV curves may become useful measures for guiding mechanical ventilation.

The effect of endotracheal suction on regional tidal ventilation and end-expiratory lung volume.

PURPOSE: To examine the impact of different endotracheal tube (ETT) suction techniques on regional end-expiratory lung volume (EELV) and tidal volume (V(T)) in an animal model of surfactant-deficient lung injury. METHODS: Six 2-week old piglets were intubated (4.0 mm ETT), muscle-relaxed and ventilated, and lung injury was induced with repeated saline lavage. In each animal, open suction (OS) and two methods of closed suction (CS) were performed in random order using both 5 and 8 French gauge (FG) catheters. The pre-suction volume state of the lung was standardised on the inflation limb of the pressure-volume relationship. Regional EELV and V(T) expressed as a proportion of the impedance change at vital capacity (%Z (VCroi)) within the anterior and posterior halves of the chest were measured during and for 60 s after suction using electrical impedance tomography. RESULTS: During suction, 5 FG CS resulted in preservation of EELV in the anterior (non-dependent) and posterior (dependent) lung compared to the other permutations, but these only reached significance in the anterior regions (p < 0.001 repeated-measures ANOVA). V(T) within the anterior, but not posterior lung was significantly greater during 5FG CS compared to 8 FG CS; the mean difference was 15.1 [95% CI 5.1, 25.1]%Z (VCroi). Neither catheter size nor suction technique influenced post-suction regional EELV or V(T) compared to pre-suction values (repeated-measures ANOVA). CONCLUSIONS: ETT suction causes transient loss of EELV and V(T) throughout the lung. Catheter size exerts a greater influence than suction method, with CS only protecting against derecruitment when a small catheter is used, especially in the non-dependent lung.

Lung volume and cardiorespiratory changes during open and closed endotracheal suction in ventilated newborn infants.

OBJECTIVES: To compare change in lung volume (DeltaV(L)), using respiratory inductive plethysmography, time to recover pre-suction lung volume (t(rec)) and the cardiorespiratory disturbances associated with open suction (OS) and closed suction (CS) in ventilated infants. DESIGN: Randomised blinded crossover trial. SETTING: Neonatal intensive care unit. PATIENTS: Thirty neonates, 20 receiving synchronised intermittent mandatory ventilation (SIMV) and 10 high-frequency oscillatory ventilation (HFOV, four receiving muscle relaxant). INTERVENTIONS: OS and CS were performed, in random order, on each infant using a 6FG catheter at -19 kPa for 6 seconds and repeated after 1 minute. OUTCOME MEASURES: DeltaV(L), oxygen saturation (Spo(2)) and heart rate were continuously recorded from 2 minutes before until 5 minutes after suction. Lowest values were identified during the 60 seconds after suction. RESULTS: Variations in all measures were seen during CS and OS. During SIMV no differences were found between OS and CS for maximum DeltaV(L) or t(rec); mean (95% CI) difference of 3.5 ml/kg (-2.8 to 9.7) and 4 seconds (-5 to 13), respectively. During HFOV t(rec) was longer during OS by 13 seconds (0 to 27) but there was no difference in the maximum DeltaV(L) of 0.1 mV (-0.02 to 0.22). A small reduction in SpO(2) with CS in the SIMV group mean difference 6% (2.1 to 9.8) was the only significant difference in physiological measurements. CONCLUSIONS: Both OS and CS produced transient variable reductions in heart rate and Spo(2). During SIMV there was no difference between OS and CS in DeltaV(L) or t(rec). During HFOV there was no difference in DeltaV(L) but a slightly longer t(rec) after OS.

Neonatal volume guarantee ventilation: effects of spontaneous breathing, triggered and untriggered inflations.

BACKGROUND: During volume guarantee (VG) ventilation the peak inflating pressure (PIP) for each ventilator inflation is adjusted to ensure the expired tidal volume (V(Te)) is close to the set V(Te). Differences in the PIP between inflations triggered by the infant's inspirations and untriggered inflations are seen. AIM: To investigate the effects of triggered and untriggered inflations on PIP and V(Te). METHODS: Neonates were ventilated with the Dräger Babylog 8000 using assist control (synchronous intermittent positive pressure ventilation) and VG modes. Continuous recordings of ventilator pressures and tidal volumes were made at 200 Hz for 10 minutes. RESULTS: In 10 infants, 6540 inflations were analysed, of which 4052 (62%) were triggered. Triggered inflations had a significantly lower mean (SD) PIP than untriggered inflations: 12.9 (4.9) vs 17.0 (3.3) cm H2O, (p<0.001). Despite this, there was no significant difference in the V(Te) of each type of inflation (103% and 101% of the set V(Te), respectively). When a triggered inflation was immediately preceded or followed by an untriggered inflation the PIP changed by about 5 cm H2O. Between adjacent inflations of the same type, the change in PIP was less than 3 cm H2O: for triggered inflations it was 0.11 (1.50) cm H2O and for untriggered inflations 0.06 (1.53) cm H2O. CONCLUSION: During VG ventilation with the Dräger Babylog 8000 the PIP was 4 cm H2O lower during triggered inflations than untriggered inflations, although the expired tidal volumes were similar.

Surfactant for meconium aspiration syndrome in full term/near term infants.

BACKGROUND: Surfactant replacement therapy has been proven beneficial in the prevention and treatment of neonatal respiratory distress syndrome (RDS). The deficiency of surfactant or surfactant dysfunction may contribute to respiratory failure in a broader group of disorders, including meconium aspiration syndrome (MAS). OBJECTIVES: To evaluate the effect of surfactant administration in the treatment of term/near-term infants with MAS. SEARCH STRATEGY: Searches were made using The Cochrane Library (Issue 4, 2006), MEDLINE and EMBASE (1985 to December 2006), previous reviews including cross-references, abstracts, conference and symposia proceedings, expert informants, and journal hand searching. No language restrictions were applied. Authors were directly contacted to provide additional data. SELECTION CRITERIA: Randomised controlled trials which evaluated the effect of surfactant administration in term infants with meconium aspiration syndrome are included in the analyses. DATA COLLECTION AND ANALYSIS: Data regarding clinical outcomes including mortality, treatment with extracorporeal membrane oxygenation (ECMO), pneumothorax, duration of assisted ventilation, duration of supplemental oxygen, intraventricular haemorrhage (any grade and severe IVH), and chronic lung disease, and were excerpted from the reports of the clinical trails by the review authors. Data analyses were done in accordance with the standards of the Cochrane Neonatal Review Group. MAIN RESULTS: Four randomised controlled trials met inclusion criteria. The meta-analysis of 4 trials enrolling 326 infants showed no statistically significant effect on mortality (typical relative risk 0.98 (95% CI 0.41, 2.39), typical risk difference 0.00 (95% CI -0.05, 0.05). The risk of requiring extracorporeal membrane oxygenation was significantly reduced in a meta-analysis of two trials (n = 208); (typical relative risk 0.64, 95% CI 0.46, 0.91; typical risk difference -0.17, 95% CI -0.30, -0.04); number needed to treat to benefit 6 (95% CI 3, 25). One trial (n = 40) reported a statistically significant reduction in the length of hospital stay [mean difference - 8 days (95% CI -14, -3 days)]. There were no statistically significant reductions in any other outcomes studied (duration of assisted ventilation, duration of supplemental oxygen, pneumothorax, pulmonary interstitial emphysema, air leaks, chronic lung disease, need for oxygen at discharge or intraventricular haemorrhage). AUTHORS' CONCLUSIONS: In infants with MAS, surfactant administration may reduce the severity of respiratory illness and decrease the number of infants with progressive respiratory failure requiring support with ECMO. The relative efficacy of surfactant therapy compared to, or in conjunction with, other approaches to treatment including inhaled nitric oxide, liquid ventilation, surfactant lavage and high frequency ventilation remains to be tested.

Effects of open endotracheal suction on lung volume in infants receiving HFOV.

OBJECTIVE: To describe the pattern and magnitude of lung volume change during open endotracheal tube (ETT) suction in infants receiving high-frequency oscillatory ventilation (HFOV). DESIGN: Prospective observational clinical study. SETTING: Tertiary neonatal intensive care unit. PATIENTS AND PARTICIPANTS: Seven intubated and muscle-relaxed newborn infants receiving HFOV. INTERVENTIONS: Open ETT suction was performed for 6 s at -100 mmHg using a 6-F catheter passed to the ETT tip after disconnection from HFOV. The HFOV was then recommenced at the same settings as prior to ETT suction. MEASUREMENTS AND RESULTS: Change in lung volume (DeltaV (L)) referenced to baseline lung volume before suction was measured with a calibrated respiratory inductive plethysmography recording from 30 s before until 60 s after ETT suction. In all infants ETT suction resulted in significant loss of lung volume. The mean DeltaV (L) during suctioning was -13 ml/kg (SD 4 ml/kg) (p<0.0001 vs. baseline, repeated-measures ANOVA), with a mean 76.5% (SD 14.1%) of this volume loss being related to circuit disconnection. After recommencing HFOV lung volume was rapidly regained with mean DeltaV (L) at 60 s being 1 ml/kg (SD 4 ml/kg) below baseline (p>0.05, Tukey post-test). CONCLUSIONS: Open ETT suction caused a significant but transient loss of lung volume in muscle-relaxed newborn infants receiving HFOV.

Death in the neonatal intensive care unit: changing patterns of end of life care over two decades.

BACKGROUND: Death remains a common event in the neonatal intensive care unit, and often involves limitation or withdrawal of life sustaining treatment. OBJECTIVE: To document changes in the causes of death and its management over the last two decades. METHODS: An audit of infants dying in the neonatal intensive care unit was performed during two epochs (1985-1987 and 1999-2001). The principal diagnoses of infants who died were recorded, as well as their apparent prognoses, and any decisions to limit or withdraw medical treatment. RESULTS: In epoch 1, 132 infants died out of 1362 admissions (9.7%), and in epoch 2 there were 111 deaths out of 1776 admissions (6.2%; p<0.001). Approximately three quarters of infants died after withdrawal of life sustaining treatment in both epochs. There was a significant reduction in the proportion of deaths from chromosomal abnormalities, and from neural tube defects in epoch 2. CONCLUSIONS: There have been substantial changes in the illnesses leading to death in the neonatal intensive care unit. These may reflect the combined effects of prenatal diagnosis and changing community and medical attitudes.

Hemodynamic disturbances associated with endovascular embolization in newborn infants with vein of Galen malformation.

OBJECTIVE: To examine hemodynamic changes following endovascular embolization in newborn infants with vein of Galen malformation and severe cardiac failure in the first week of life. STUDY DESIGN: Over a recent 5-year period, nine such infants were identified. In seven of these infants, changes in arterial blood pressure were analyzed in relation to the timing of embolization procedures. RESULTS: A significant increase in arterial blood pressure was noted after most embolizations. In two infants, this systemic hypertension was severe and treated using intravenous antihypertensive drugs. Both infants subsequently developed complete infarction of both cerebral hemispheres with sparing of the brainstem and cerebellum. Mortality in the nine infants was 33%, and 83% of the survivors were neurologically normal or near normal at follow-up. CONCLUSION: The systemic hypertension observed following endovascular embolizations may provide a protective mechanism to maintain cerebral blood flow after reperfusion injury. Lowering blood pressure in this situation may therefore be detrimental.

Volume guarantee ventilation, interrupted expiration, and expiratory braking.

BACKGROUND: In volume guarantee ventilation with the Dräger Babylog 8000 ventilator, inspiratory and expiratory flows are monitored and the expiratory tidal volume calculated following each inflation. The pressure for the next inflation is modified to ensure the expired tidal volume is close to the set value. AIM: To investigate interrupted expiration observed during volume guarantee ventilation of spontaneously breathing, ventilated infants. METHODS: Spontaneously breathing infants, ventilated with volume guarantee, had recordings of gas flow, ventilator pressures, tidal volume waveforms, oximetry, heart rate, and transcutaneous oxygen and carbon dioxide during 10 minute recordings. RESULTS: A total of 6540 inflations were analysed from 10 infants; 62% were triggered. Two different patterns were found: (1) Normal volume guarantee pattern with 97% of triggered and 91% untriggered inflations. It had a normal expiratory curve and a mean expired tidal volume within 3% of the set volume, but a large variation due to the babies' breathing. (2) A pattern of interrupted expiratory flow after approximately 3% of inflations due to a small inspiration (approximately 1.3 ml/kg) during expiration. This led the ventilator to calculate an inappropriate total expired tidal volume for that inflation and an increase in the pressure for the next inflation. CONCLUSIONS: After about 3% of inflations, with volume guarantee ventilation, interruption of the expiration causes an increased pressure for the next inflation of approximately 4.9 cm H2O, compared with normal volume guarantee inflation. The interrupted expiration is most likely to be due to diaphragmatic braking.

Neonatal resuscitation 3: manometer use in a model of face mask ventilation.

BACKGROUND: Adequate ventilation is the key to successful neonatal resuscitation. Positive pressure ventilation (PPV) is initiated with manual ventilation devices via face masks. These devices may be used with a manometer to measure airway pressures delivered. The expiratory tidal volume measured at the mask (V(TE(mask))) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. AIM: To assess the effect of viewing a manometer on the peak inspiratory pressures used, the volume delivered, and leakage from the face mask during PPV with two manual ventilation devices in a model of neonatal resuscitation. METHODS: Participants gave PPV to a modified resuscitation mannequin using a Laerdal infant resuscitator and a Neopuff infant resuscitator at specified pressures ensuring adequate chest wall excursion. Each participant gave PPV to the mannequin with each device twice, viewing the manometer on one occasion and unable to see the manometer on the other. Data from participants were averaged for each device used with the manometer and without the manometer separately. RESULTS: A total of 7767 inflations delivered by the 18 participants were recorded and analysed. Peak inspiratory pressures delivered were lower with the Laerdal device. There were no differences in leakage from the face mask or volumes delivered. Whether or not the manometer was visible made no difference to any measured variable. CONCLUSIONS: Viewing a manometer during PPV in this model of neonatal resuscitation does not affect the airway pressure or tidal volumes delivered or the degree of leakage from the face mask.

Neonatal resuscitation 2: an evaluation of manual ventilation devices and face masks.

BACKGROUND: The key to successful neonatal resuscitation is effective ventilation. Little evidence exists to guide clinicians in their choice of manual ventilation device or face mask. The expiratory tidal volume measured at the mask (V(TE(mask))) is a good estimate of the tidal volume delivered during simulated neonatal resuscitation. AIM: To compare the efficacy of (a) the Laerdal infant resuscitator and the Neopuff infant resuscitator, used with (b) round and anatomically shaped masks in a model of neonatal resuscitation. METHODS: Thirty four participants gave positive pressure ventilation to a mannequin at specified pressures with each of the four device-mask combinations. Flow, inspiratory tidal volume at the face mask (V(TI(mask))), V(TE(mask)), and airway pressure were recorded. Leakage from the mask was calculated from V(TI(mask)) and V(TE(mask)). RESULTS: A total of 10,780 inflations were recorded and analysed. Peak inspiratory pressure targets were achieved equally with the Laerdal and Neopuff resuscitators. Positive end expiratory pressure was delivered with the Neopuff but not the Laerdal device. Despite similar peak pressures, V(TE(mask)) varied widely. Mask leakage was large for each combination of device and mask. There were no differences between the masks. CONCLUSION: During face mask ventilation of a neonatal resuscitation mannequin, there are large leaks around the face mask. Airway pressure is a poor proxy for volume delivered during positive pressure ventilation through a mask.

Clostridium difficile associated severe enterocolitis: a feature of Hirschsprung's disease in a neonate presenting late.

We report a case of Hirschsprung's disease presenting late in the newborn period with severe enterocolitis and Clostridium difficile toxin detectable in the stool. Enterocolitis associated with Hirschsprung's disease is a potentially fatal complication that may occur at presentation or later in the life of an affected child. Its association with toxin-producing Clostridium difficile growth in the bowel may be under recognized, especially in newborns.

Clinical course and medical management of neonates with severe cardiac failure related to vein of Galen malformation.

BACKGROUND: Neonatal presentation of vein of Galen aneurysmal malformations (VGAMs) with intractable cardiac failure is considered a poor prognostic sign. Interventional neuroradiology with embolisation has been shown to control cardiac failure, but there is a perception that neurological outcome in survivors is poor. OBJECTIVE: To determine if aggressive intensive care and anaesthetic management of cardiac failure before urgent embolisation can influence morbidity and mortality. PATIENTS: Nine newborns (four boys, five girls) were diagnosed with symptomatic vein of Galen malformations in the neonatal period during the period 1996-2001. Eight developed intractable high output cardiac failure requiring initial endovascular treatment in the first week of life. RESULTS: The immediate outcome after a series of endovascular procedures was control of cardiac failure and normal neurological function in six (66%) patients, one death from intractable cardiac failure in the neonatal period, and two late deaths with severe hypoxic-ischaemic neurological injury (33% mortality). Clinical review at 6 months to 4 years of age showed five infants with no evidence of neurological abnormality or cardiac failure and one child with mild developmental delay (11%). CONCLUSIONS: Aggressive medical treatment of cardiac failure and early neurointervention combined with modern neuroanaesthetic care results in good survival rates with low morbidity even in cases of high risk VGAM presenting in the immediate perinatal period with cardiac failure. Systemic arterial vasodilators improve outcome in neonates with cardiac failure secondary to VGAM. Excessive beta adrenergic stimulation induced by conventional inotropic agents may exacerbate systemic hypoperfusion.

Endovascular management of vein of Galen aneurysmal malformations presenting in the neonatal period.

BACKGROUND AND PURPOSE: Neonates with vein of Galen aneurysmal malformations (VGAMs) presenting with cardiac failure have high morbidity and mortality, and outcomes are significantly better in those presenting in later childhood. Neurologic outcomes in survivors are perceived to be uniformly poor, which may lead to the neonate being denied treatment. We assessed outcomes of modern neonatal intensive care and endovascular embolization in a consecutive series of such neonates presenting with cardiac failure. METHODS: Between 1996 and 1998, five infants (three male, two female) were diagnosed with symptomatic VGAMs in the first week of life, four of whom had intractable, high-output cardiac failure and underwent initial endovascular treatment. There were 15 endovascular procedures and one neurosurgical clipping in these five patients. Transarterial and transvenous routes were required, using multiple embolic agents. We emphasized the use of sonographically guided, percutaneous transtorcular-venous-access, moveable-core guidewire as an embolic agent; routine MR imaging; and MR angiography. RESULTS: Immediate outcomes included control of cardiac failure with normal neurologic function in four (80%) patients and one (20%) death from intractable cardiac failure. On follow-up examination, three (60%) infants showed no evidence of neurologic abnormality or cardiac failure; one (20%) infant showed moderate developmental delay. Two have had no further shunting on angiography, one has minimal flow, and one is awaiting follow-up imaging. CONCLUSION: Endovascular therapy with modern neuroanesthetic and neurointensive care can provide good outcomes even in the highest-risk neonates with VGAMs and cardiac failure. If medical management of cardiac failure fails, and there is no evidence of gross cerebral parenchymal damage on imaging, urgent endovascular treatment is feasible and can reduce the almost-100% mortality otherwise expected, without invariably severe morbidity. Use of multiple embolization strategies in multiple stages usually is necessary in these patients, and novel approaches and embolic agents may be necessary.

Left-lung-collapse bronchial deformation in giant omphalocele.

Five infants with giant omphalocele had persistent collapse of the left lung and required prolonged respiratory support. Narrowing of the left main bronchus, reversible with positive end-expiratory pressure, was identified radiographically in 3 infants, and we postulate that this relates to distortion of the bronchus within the constraints of the elongated, narrow thoracic cavity characteristic of these patients. The lung collapse may be precipitated by manipulation (reduction or attempted reduction) of the omphalocele. J Pediatr Surg 36:846-850.

Upper cervical spinal cord injury in neonates: the use of magnetic resonance imaging.

Neonatal upper cervical spinal cord injury is associated with rotational forceps delivery and presents with quadriparesis and diaphragmatic paralysis. The underlying pathology determines neurologic outcome but is difficult to assess clinically or with simple radiographic techniques. We report 4 cases in which early magnetic resonance imaging demonstrated the extent and severity of the injury and guided management.