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Objective: Lung ultrasound (LUS) is an emerging tool that may be used in the diagnosis and follow-up of children with viral bronchiolitis. In this study, we describe LUS abnormalities in children receiving invasive mechanical ventilation (IMV) for severe bronchiolitis in the pediatric intensive care unit (PICU). Our aim was to semiquantify the loss of aeration and examine the association between serial LUS scores and oxygenation anomaly, as a marker of disease severity., Design: Prospective, observational study in a single-center PICU., Methods: LUS was performed by multiple observers using two different LUS scoring systems (counting B-lines and aeration score) in 17 patients in the PICU, generating 320 images. Oxygen saturation index (OSI) was the primary outcome marker to describe the severity of oxygenation anomaly., Results: Pulmonary aeration was moderately impaired with a homogeneous anterolateral pattern. LUS scores worsened after 24 hours, to improve in subsequent days. Both LUS scores were positively correlated with OSI on the first day of IMV (counting B-lines P = .034, r = .52 and LUS aeration score P = .017, r = .57), but not thereafter. There was considerable variability in the LUS scores despite moderate to high agreement between the observers., Conclusions: In children receiving IMV for severe bronchiolitis, pulmonary aeration is moderately impaired. LUS scores positively correlate with severity of oxygenation anomaly only in the acute phase of disease. We speculate that with the progression of disease other factors affect LUS patterns (eg, fluid overload, atelectasis), which may complicate the interpretation of LUS in follow-up of this specific cohort in the PICU., (© 2020 Wiley Periodicals LLC.)

Bronchiolitis is one of the most frequent reasons for Pediatric Intensive Care Unit (PICU) admission in children less than 1 year of age. It causes a wide spectrum of clinical scenarios from mild to severe respiratory failure and supportive therapy range from high flow nasal cannula (HFNC) to nonconventional ventilation and extra corporeal membrane oxygenation (ECMO) in the most severe forms. Aim of this article is to review the available ventilation mode in children with bronchiolitis and the scientific evidence. The main medical databases were explored to search for clinical trials that address management strategies for respiratory support of infants with respiratory syncytial virus (RSV) infection. HFNC use is increasing and it seems to be useful as first line therapy in the emergency room and in the pediatric ward to prevent PICU admission but it is not clear yet if it is equivalent to noninvasive ventilation (NIV). NIV use in bronchiolitis is well established, mainly in continuous positive airway pressure mode in moderate and severe bronchiolitis. A mild evidence towards use of NIV to prevent endotracheal intubation is raising from few studies. Finally, for patients who failed a NIV trial, endotracheal intubation should be considered as the best option to support ventilation with conventional, nonconventional mode and ECMO in the most severe acute respiratory distress syndromes. There is a lack of quality studies for the use of any of the proposed ventilatory support in infants with bronchiolitis, especially in the severe forms. Nevertheless, in the last two decades daily use of noninvasive positive pressure supports have reached a large consensus based on clinical judgement and weak published evidence. We need specific and clear guidelines on which is the optimal management of these patients, and more robust randomized clinical trials to best evaluate timing and efficacy of HFNC and NIV use.

Background: Infants have to actively maintain their end expiratory lung volume (EELV). In mechanically ventilated infants, the diaphragm stays activated until the end of expiration (tonic activity), contributing to EELV maintenance. It is unclear whether tonic activity compensates for the lack of laryngeal braking due to intubation or if it is normally present., Objective: To determine if tonic diaphragm activity remains after extubation in infants, and if it can be observed in older children., Methods: Prospective observational study of pediatric patients ventilated for >24 hr. Diaphragm electrical activity (EAdi) was recorded using a specific nasogastric catheter during four periods: (i) the acute phase, (ii) pre-extubation, (iii) post-extubation, and (iv) at PICU discharge. Tonic EAdi was defined as the EAdi in the last quartile of expiration., Results: Fifty-five patients, median age 10 months (Interquartile range: 1-48) were studied. In infants (<1 year, n = 28), tonic EAdi was always present, and represented 33% (22-43) of inspiratory EAdi at PICU discharge. No significant change was observed between pre- and post-extubation periods. In older patients (n = 27), tonic activity was negligible as a whole, but 10 patients exhibited significant tonic EAdi at one time-point during PICU stay. Bronchiolitis was the only independent factor associated with tonic EAdi., Conclusions: In infants, tonic EAdi remains involved in ventilatory control after extubation and restoration of laryngeal braking. Tonic EAdi may play a pathophysiological role in bronchiolitis and it can be reactivated in older patients. The interest of tonic EAdi as a tool to titrate mechanical ventilation warrants further evaluation., (© 2015 Wiley Periodicals, Inc.)

Objective: To assess the association of the introduction of a high-flow nasal cannula (HFNC) protocol with clinical outcomes and hospital charges of infants with bronchiolitis initially admitted to the PICU., Methods: We conducted a retrospective, nonrandomized, preintervention-postintervention study of infants with bronchiolitis initially admitted to the PICU for HFNC. We compared patients admitted in the 24 months before and after protocol initiation for HFNC use on the general wards. The primary outcome assessed was length of hospital stay (LOS), and the secondary outcomes included total hospital charges, intubation, and 30-day readmission. We conducted bivariate analysis using χ² test for categorical variables and Student's t test or Wilcoxon rank sum test for continuous variables., Results: Two hundred and ninety patients were admitted to the PICU on HFNC; 120 patients were admitted before and 170 admitted after the introduction of HFNC use on the general wards. Comparing the 2 groups, the median LOS was significantly reduced (4 days vs 3 days; P < .001), as was the median total hospital charges ($12 257 vs $9337; P < .001). After starting HFNC use on the wards, 30% of patients initially admitted to the PICU were ultimately transferred to the wards while still on HFNC. There was no difference in intubation rate or 30-day readmission between the 2 groups., Conclusions: For bronchiolitis patients initially admitted to the PICU, initiating a guideline for HFNC use on the general pediatric wards is associated with reduced total hospital LOS and total hospital charges, with no difference in intubation rates or 30-day readmission., (Copyright © 2015 by the American Academy of Pediatrics.)

Background and Aims: Bronchiolitis is a common cause of critical illness in infants. Inhaled β(2)-agonist bronchodilators are frequently used as part of treatment, despite unproven effectiveness. The purpose of this study was to describe the physiologic response to these medications in infants intubated and mechanically ventilated for bronchiolitis., Materials and Methods: We conducted a prospective trial of albuterol treatment in infants intubated and mechanically ventilated for bronchiolitis. Before and for 30 minutes following inhaled albuterol treatment, sequential assessments of pulmonary mechanics were determined using the interrupter technique on repeated consecutive breaths., Results: Fifty-four infants were enrolled. The median age was 44 days (25-75%; interquartile range (IQR) 29-74 days), mean hospital length of stay (LOS) was 18.3 ± 13.3 days, mean ICU LOS was 11.3 ± 6.4 days, and mean duration of mechanical ventilation was 8.5 ± 3.5 days. Fifty percent (n = 27) of the infants were male, 81% (n = 44) had public insurance, 80% (n = 41) were Caucasian, and 39% (n = 21) were Hispanic. Fourteen of the 54 (26%) had reduction in respiratory system resistance (Rrs) that was more than 30% below baseline, and were defined as responders to albuterol. Response to albuterol was not associated with demographic factors or hospitalization outcomes such as LOS or duration of mechanical ventilation. However, increased Rrs, prematurity, and non-Hispanic ethnicity were associated with increased LOS., Conclusions: In this population of mechanically ventilated infants with bronchiolitis, relatively few had a reduction in pulmonary resistance in response to inhaled albuterol therapy. This response was not associated with improvements in outcomes.

Objectives: To evaluate the association between deadspace/tidal volume ratio (Vd/Vt) and gas exchange variables: Pao2, Paco2, Pao2/Fio2, arterial/alveolar oxygen tension ratio (Pao2/PAo2), alveolar-arterial oxygen tension difference/arterial oxygen tension ratio (P(A-a)o2/Pao2), carbon dioxide production (Vco2), ventilation index ([Paco2 x peak inspiratory pressure x mechanical respiratory rate]/1000), and oxygenation index ([mean airway pressure x Fio2 x 100]/Pao2), all measured at an early stage in children with obstructive acute respiratory failure., Design: Prospective, cross-sectional, observational study., Setting: Pediatric intensive care unit, university hospital., Patients: Twenty-nine infants with acute bronchiolitis, defined according to clinical and radiologic criteria. Children with chronic pulmonary disease, neuromuscular disease, congenital cardiopathies, or hemodynamic instability were excluded., Interventions: Measurements were made between 24 and 72 hrs of mechanical ventilation using volumetric capnography and arterial blood gas analysis., Measurements and Main Results: The following variables significantly correlated with Vd/Vt, calculated using Spearman's correlation coefficient (rs): Pao2 (rs = -0.63, p < .001), Pao2/Fio2 (rs = -0.56, p = .002), Pao2/PAo2 (rs = -0.46, p = .012), P(A-a)o2/Pao2 (rs = -0.46, p = .012), Paco2 (rs = 0.51, p = .005), Vco2 (rs = -0,62, p < .01), oxygenation index (rs = 0.48, p = .009), and ventilation index (rs = -0.53, p = .003). A statistically significant association was found between an increase in Vd/Vt and severity of lung injury, defined as Pao2/Fio2 <200 (p = .03, Mann-Whitney)., Conclusions: In the study population, Vd/Vt not only reflected ventilatory disorders, as is well recognized, but also was associated with disturbances of oxygenation. These results warrant further evaluation of the usefulness of serial measurement of Vd/Vt as a marker of disease severity in severe acute bronchiolitis and other causes of respiratory failure.

Objective: To determine the effect of forced deflation maneuvers on respiratory mechanics and to assess the reproducibility of such measurements in intubated infants with lung disease., Design and Setting: Prospective study in the pediatric intensive care unit of a university children's hospital., Patients: Ten clinically stable infants requiring mechanically assisted ventilation for acute pulmonary disease, mean age 5.9 months (1-18), mean weight 5.8 kg (3.2-13)., Interventions: Two sets of measurements of compliance (Crs) and resistance (Rrs) were obtained at 20-min intervals both before and after +40/-40 cmH(2)O forced deflation maneuvers. Forced deflation measurements were repeated at the end of the study., Results: . Forced deflation caused a significant increase in Crs from 0.53+/-0.09 and 0.58+/-0.11 ml/cmH(2)O/kg to 0.71+/-0.11 and 0.68+/-0.11 ml/cmH(2)O/kg. Rrs measurements did not differ. The low coefficients of variation for repeated measures of the baseline measurements (Crs 4.2+/-0.5%, Rrs 7.1+/-0.8%, for forced vital capacity 8.6+/-2.5%, maximum expiratory flows at 25% vital capacity 16.0%+/-3.3%) confirmed the good reproducibility during stable conditions., Conclusions: Inflation and deflation maneuvers affect subsequent measurements of respiratory system compliance but not measurements of maximum expiratory flow-volume relationships in intubated infants, probably through recruitment of lung volume. Careful interpretation and planning of the sequence of infant pulmonary function testing is necessary to reassure that changes are not related to short-term alterations in volume history.

Unlabelled: We wished to retrospectively evaluate the effects of permissive hypercapnia (PHY) on barotrauma, mortality and length of stay when applied to ventilated infants with respiratory syncytial virus (RSV) bronchiolitis. Nineteen control infants with RSV induced respiratory failure were treated with conventional ventilation (April 1991-January 1994), after which time PHY was adopted as unit policy. A further 28 infants were then treated with PHY (January 1994 April 1996). Demographic and physiological data were collected from admission, and outcome variables including length of stay, barotrauma and mortality were recorded. The PHY group showed a significantly higher mean pCO2 (7.6 vs 5.2 kPa), a lower mean pH (7.34 vs 7.40), and a reduction in maximal peak inspiratory pressures (25 vs 30 cmH2O). Mortality, barotrauma, use of neuromuscular blockade and nosocomial infection did not differ between groups. There was a trend towards increased length of ventilation in the PHY group (median 7 vs 5 days)., Conclusion: Based on this retrospective data we can show no benefit for the use of permissive hypercapnia as a ventilatory strategy in this patient group. A prospective randomised controlled trial is warranted to accurately assess the outcome variables and cost implications of this strategy.

In the five years which have passed since the previous review, the literature has been concerned more with the ways in which ventilators may be applied to patients and the effects of differing patterns of ventilation than with the design philosophy of the ventilators themselves. This account should be read in conjunction with that of 1982 [1].