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Clinicians have little guidance on the time needed before assessing the effect of a mean airway pressure change during high-frequency oscillatory ventilation. We aimed to determine: 1) time to stable lung volume after a mean airway pressure change during high-frequency oscillatory ventilation and 2) the relationship between time to volume stability and the volume state of the lung., Design: Prospective observational study., Setting: Regional quaternary teaching hospital neonatal ICU., Patients: Thirteen term or near-term infants receiving high-frequency oscillatory ventilation and muscle relaxants., Interventions: One to two cm H 2 O mean airway pressure changes every 10 minutes as part of an open lung strategy based on oxygen response., Measurements and Main Results: Continuous lung volume measurements (respiratory inductive plethysmography) were made during the mean airway pressure changes. Volume signals were analyzed with a biexponential model to calculate the time to stable lung volume if the model R 2 was greater than 0.6. If volume stability did not occur within 10 minutes, the model was extrapolated to maximum 3,600 s. One-hundred ninety-six mean airway pressure changes were made, with no volume change in 33 occurrences (17%). One-hundred twenty-five volume signals met modeling criteria for inclusion; median (interquartile range) R 2 , 0.96 (0.91-0.98). The time to stable lung volume was 1,131 seconds (718-1,959 s) (mean airway pressure increases) and 647 seconds (439-1,309 s) (mean airway pressure decreases), with only 17 (14%) occurring within 10 minutes and time to stability being longer when the lung was atelectatic., Conclusions: During high-frequency oscillatory ventilation, the time to stable lung volume after a mean airway pressure change is variable, often requires more than 10 minutes, and is dependent on the preceding volume state., Competing Interests: Dr. Tingay was supported by a National Health and Medical Research Council Clinical Research Fellowship (Grant ID 491286 and 1053889). Drs. Tingay, Kiraly, and Mills are supported by the Victorian Government Operational Infrastructure Support Program. Dr. Dargaville has not disclosed any potential conflicts of interest., (Copyright © 2021 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.)

Background: An Australian study including 4433 children found that delayed Diphtheria-Tetanus-acellular Pertussis-containing vaccination was associated with reduced risk of developing atopic dermatitis (AD) before age 1 year., Objective: We assessed whether delayed vaccination against diphtheria, tetanus, acellular pertussis, polio, and Haemophilus influenzae type b (Diphtheria, Tetanus, acellular Pertussis - Inactivated Polio vaccine - Haemophilus influenzae type b [DTaP]) was associated with a reduced risk of new cases of AD before age 1 year in Denmark., Methods: We used nationwide registers to follow 883,160 children born in Denmark from 1997 to 2012. Binary regression models adjusting for potential confounding factors were applied to estimate relative risks (adjusted relative risks [aRRs]) of developing AD among children with delayed DTaP vaccination (defined as given 1 month or more after the recommended age) compared with timely vaccinated children., Results: Among 143,429 children with a delayed first dose of DTaP, 4,847 (3.4%) developed AD between age 4 months and 1 year, compared with 27,628 (3.7%) among 739,731 children not having delayed DTaP (aRR 0.94; 95% CI, 0.91-0.97). The aRR was 0.94 (95% CI, 0.90-0.99) for children with a delayed second dose, and the aRR was 0.88 (95% CI, 0.82-0.93) when comparing children with delayed first and second doses with all timely vaccinated children., Conclusions: The results support the hypothesis that delayed vaccination with DTaP is associated with reduced risk of developing new cases of AD after age 4 months. The dose-dependent relationship strengthens the evidence of a causal relationship. Some countries are introducing maternal pertussis vaccination and delaying the first dose of DTaP, providing a possibility for further testing the hypothesis., (Copyright © 2020 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: The World Health Organization recommends high-dose vitamin A supplementation (VAS) for children above six months of age in low-income countries. VAS has been associated with up-regulation of the Th2 response. We aimed to determine if VAS is associated with atopy in childhood., Methods: Infants in Guinea-Bissau were randomly allocated VAS or placebo, either at six and nine months of age, or only at nine months of age. At six months of age, children were furthermore randomized to measles vaccine or inactivated polio vaccine. At nine months of age all children received measles vaccine. Children were revisited seven years later and skin prick testing was performed. Atopy was defined as a skin prick reaction ≥ 3 mm., Results: 40 of 263 children (15%) were atopic. Overall VAS had no significant effect on the risk of atopy (Prevalence Ratio 1.23; 95% CI 0.69-2.18). The Prevalence Ratio was 1.60 (0.66-3.90) for males and 1.00 (0.46-2.15) for females., Conclusions: There was no significant effect of VAS in infancy on atopy later in childhood. The role of infant VAS in the development of atopy is still unclear.

Background: Closed endotracheal suction interferes with mechanical ventilation received by infants, but the change to ventilation may be different when ventilator modes that target expired tidal volume (VT(e)) are used., Objective: To measure airway pressure and tidal volume distal to the endotracheal tube (ETT) during and after closed suction in a volume-targeted ventilation mode with the Dräger Babylog 8000+, and to determine the time until VT(e) returns to the baseline level., Methods: In this benchtop study, closed suction was performed on 2.5- to 4.0-mm ETTs connected to a test lung. 5-8 French suction catheters were used at suction pressures of 80-200 mm Hg during tidal-volume-targeted ventilation., Results: During catheter insertion and suction, circuit inflating pressure increased and tidal volume was maintained, except when a large catheter relative to the ETT was used, in which case tidal volume decreased. End-expiratory pressure distal to the ETT was reduced during suction by up to 75 cm H(2)O while circuit end-expiratory pressure was unchanged. Reduction in end-expiratory pressure distal to the ETT was greatest with large catheters and high suction pressures. Following suction, circuit and tracheal inflating pressures increased and tidal volume increased before returning to baseline in 8-12 s., Conclusions: Closed endotracheal suction interferes with ventilator function in volume-targeted mode, with substantially negative intratracheal pressure during suction, and the potential for high airway pressures and tidal volumes following the procedure. These effects should be considered and pressure limits set appropriately whenever using volume-targeted ventilation., (Copyright © 2010 S. Karger AG, Basel.)

Objective: To determine energy dose and number of biphasic direct current shocks for pediatric ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT)., Design: Observation of preshock and postshock rhythms, energy doses, and number of shocks., Setting: Pediatric hospital., Patients: Shockable ventricular dysrhythmias., Interventions: None., Measurements and Main Results: Forty-eight patients with VF or pulseless VT received external shock at 1.7 ± 0.8 (mean ± SD) J/kg. Return of spontaneous circulation (ROSC) occurred in 23 (48%) patients with 2.0 ± 1.0 J/kg, but 25 (52%) patients remained in VF after 1.5 ± 0.7 J/kg (p = .05). In 24 non-responding patients, additional 1-8 shocks (final dose, 2.8 ± 1.2 J/kg) achieved ROSC in 14 (58%) with 2.6 ± 1.1 J/kg but not in 10 (42%) with 3.2 ± 1.2 J/kg (not significant). Overall, 37 (77%) patients achieved ROSC with 2.2 ± 1.1 J/kg (range, 0.5-5.0 J/kg). Eight patients without ROSC recovered with cardiopulmonary bypass and internal direct current shock. At 13 subsequent episodes of VF or VT among eight patients, five achieved ROSC and survived. In combined first and subsequent resuscitative episodes, doses in the range of 2.5 to < 3 J/kg achieved most cases of ROSC. Survival for > 1 yr was seen in 28 (78%) of 36 patients with VF and seven (58%) of 11 patients with VT, with 35 (73%) overall. Lack of ROSC was associated with multiple shocks (p = .003). Repeated shocks with adhesive pads had significantly less impedance (p < .001). Pads in an anteroposterior position achieved highest ROSC rate. Internal shock for another 48 patients with VF or VT achieved ROSC in 28 (58%) patients with 0.7 ± 0.4 J/kg but not in 20 patients with 0.4 ± 0.3 J/kg (p = .01). Nineteen of the nonresponders who received additional internal 1-9 shocks at 0.6 ± 0.5 J/kg and one patient given extracorporeal membrane oxygenation all recovered, yielding 100% ROSC, but 1-yr survival tallied 43 (90%) patients., Conclusions: The initial biphasic direct current external shock dose of 2 J/kg for VF or pulseless VT is inadequate. Appropriate doses for initial and subsequent shocks seem to be in the range of 3-5 J/kg. Multiple shocks do not favor ROSC. The dose for internal shock is 0.6-0.7 J/kg.

Objective: To determine cardioversion doses of biphasic DC shock for paediatric atrial dysrhythmias., Design: Prospective recording of energy, pre-shock and post-shock rhythms., Setting: Paediatric hospital., Patients: Shockable atrial dysrhythmias., Main Results: Forty episodes of atrial dysrhythmias among 25 children (mean age 6.8+/-7.1 years, mean weight 28.2+/-28.5 kg) were treated with external shock. The first shock converted the dysrhythmia to sinus rhythm in 25 episodes. Cardioversion occurred in 2 of 8 (25%) episodes with a dose of <0.5 J/kg, 14 of 16 (88%) with a dose of 0.5-1.0 J/kg and 9 of 16 (56%) with a dose of >1.0 J/kg (p=0.01, Fisher's exact test). Ten of 15 initially non-responsive episodes were cardioverted with additional shocks at 1.1+/-0.6 J/kg (range 0.5-2.1 J/kg). Of the remaining 5 unresponsive episodes, 2 of ventricular fibrillation (induced by unsynchronized shock) were successfully defibrillated, and 3 were managed with cardiopulmonary bypass. Among 11 additional children (mean age 4.3+/-6.8 years, mean weight 18.1+/-22.0 kg), 18 episodes of atrial dysrhythmias were treated with internal shock which successfully cardioverted all episodes with one or more shocks at 0.4+/-0.2 J/kg., Conclusions: In rounded doses, recommended initial external cardioversion doses are 0.5-1.0 J/kg and subsequently up to 2 J/kg, internal cardioversion doses are 0.5 J/kg., (Copyright 2010 Elsevier Ireland Ltd. All rights reserved.)

We aimed to identify the effect of suction pressure and catheter size on change in lung volume during open and closed endotracheal suction. Anesthetized piglets (n = 12) were intubated with a 4.0-mm endotracheal tube. Lung injury was induced with saline lavage. Three suction methods (open, closed in-line, and closed with a side-port adaptor) were performed in random order using 6, 7, and 8 French gauge (FG) catheters, at vacuum pressures of 80, 140, and 200 mm Hg. Lung volume change was measured with respiratory inductive plethysmography. Overall, open suction resulted in greater lung volume loss during and at 60-s postsuction than either closed method (p < 0.001). When open and closed methods were analyzed separately, volume change was independent of catheter size and suction pressure with open suction. With closed suction, volume loss increased with larger catheter sizes and higher suction pressures (p < 0.001). With an 8-FG catheter and suction pressure of 140 or 200 mm Hg, volume loss was equivalent with open and closed suction. Lung volume changes are influenced by catheter size and suction pressure, as well as suction method. With commonly used suction pressures and catheter sizes, closed suction has no advantage in preventing loss of volume in this animal model.

In newborn infants, closed endotracheal tube (ETT) suction may reduce associated adverse effects, but it is not clear whether ventilation is maintained during the procedure. We aimed to determine the effect of ETT size, catheter size, and suction pressure on ventilation parameters measured distal to the ETT. Suction was performed on a test lung, ventilated with conventional (CMV) and high-frequency oscillatory ventilation (HFOV) using ETT sizes 2.5-4.0 mm, catheter sizes 5-8 French gauge (Fr), and suction pressures 80-200 mm Hg. Tracheal and circuit peak inspiratory pressure, positive end-expiratory pressure, and tracheal tidal volume (VT) were recorded for each suction episode. During both CMV and HFOV, tracheal pressures and VT were considerably reduced by suctioning; this reduction was dependent on the combination of ETT, catheter, and suction pressure. Loss of VT, inflation pressure (CMV), and pressure amplitude (HFOV) occurred primarily with insertion of the catheter, and loss of end-expiratory pressure (CMV) and mean tracheal pressure (HFOV) occurred with the application of suction. Circuit pressures were reduced to lesser degree. We conclude that airway pressures and VT are not maintained during closed endotracheal suction with either CMV or HFOV, and choice of equipment and settings will affect the degree of interruption to ventilation.

Endotracheal tube (ETT) suction is the most frequently performed invasive procedure in ventilated newborn infants and is associated with adverse effects related to negative tracheal pressure. We aimed to measure suction catheter gas flow and intratracheal pressure during ETT suction of a test lung and develop a mathematical model to predict tracheal pressure from catheter and ETT dimensions and applied pressure. Tracheal pressure and catheter flow were recorded during suction of ETT sizes 2.5-4.0 mm connected to a test lung with catheters 5-8 French Gauge and applied pressures of 80-200 mm Hg. The fraction of applied pressure transmitted to the trachea was calculated for each combination, and data fitted to three nonlinear models for analysis. Tracheal pressure was directly proportional to applied pressure (r = 0.82-0.99), and catheter flow fitted a turbulent flow model (R = 0.85-0.96). With each ETT, increasing catheter size resulted in greater catheter flow (p < 0.0001) and thus lower intratracheal pressure (p < 0.0001). The fraction of applied pressure transmitted to the trachea was accurately modeled using ETT and catheter dimensions (R = 0.98-0.99). Negative tracheal pressure during in vitro ETT suction is directly proportional to applied pressure. This relationship is determined by ETT and catheter dimensions.

Objective: To compare the effectiveness of open and closed endotracheal suction in recovering thin and thick secretions in normal and injured lungs during conventional and high frequency ventilation., Design and Setting: Randomised study in a paediatric intensive care model in the animal research laboratory of a tertiary paediatric hospital., Subjects: 16 New Zealand White rabbits., Interventions: Anaesthetised animals were intubated with a 3.5-mm endotracheal tube. Simulated thin and thick secretions (iopamidol 2 ml, a watery radio-opaque fluid, and fluorescent mucin 1 ml) were instilled in turn 1 cm below the tube tip through a catheter placed via a tracheostomy. Open or closed suction, randomly assigned, was applied for 6s at -140 mmHg using a 6-F gauge catheter. Following lung injury with repeated saline lavage the procedure was repeated on conventional and high frequency ventilation., Measurements and Results: Iopamidol recovery was determined by digitally subtracting the post-contrast and post-suction radiographic images. Mucin recovery was determined by fluorescence assay of the aspirate. In the normal lung similar amounts were recovered by both suction methods. In the lavaged lung closed suction recovered less iopamidol during conventional (22 +/- 7.5%) and high frequency ventilation (11 +/- 2.4%) than open suction (36 +/- 2% and 22 +/- 8.1%, respectively). Mucin recovery was less with closed suction during conventional 32 +/- 28 microl) and high frequency ventilation (30 +/- 31 microl) than with open suction (382 +/- 235 microl and 24 +/- 153 microl)., Conclusions: In the injured lung closed suction was less effective than open suction at recovering thin and thick simulated secretions, irrespective of ventilation mode.