Barotrauma not related to type of positive pressure ventilation during severe asthma exacerbations in children

High-flow nasal cannula in children with asthma exacerbation: A review of current evidence

Asthma is the commonest obstructive airway disease and the leading cause of morbidity in children. In the pediatric population, acute exacerbations of asthma are a frequent cause of presentations and hospital admissions. An acute asthma exacerbation is potentially life-threatening; it is predominantly treated using conventional oxygen therapy with bronchodilators and systemic corticosteroids. The treatment of those who do not respond to conventional therapy is escalated to noninvasive positive pressure ventilation (NIPPV) before invasive ventilation. Although NIPPV has demonstrated benefits and safety, it still has limitations such as treatment intolerance caused mainly by discomfort and complications. High-flow oxygen therapy administered through a nasal cannula (HFNC) provides respiratory support with adequate airway humidity and has demonstrated safety and benefits in clinical practice. In the present review, we discuss HFNC and variations in HFNC use, focusing on its feasibility and current evidence of using it on children with asthma exacerbations.

Noninvasive Ventilation and Outcomes in Bronchiolitis

OBJECTIVES

Evaluation of potential benefits of noninvasive ventilation for bronchiolitis has been precluded in part by the absence of large, adequately powered studies. The objectives of this study were to characterize temporal trends in and associations between the use of noninvasive ventilation in bronchiolitis and two clinical outcomes, invasive ventilation, and cardiac arrest.

DESIGN

Multicenter retrospective cross-sectional study.

SETTING

Forty-nine U.S. children's hospitals participating in the Pediatric Health Information System database.

PATIENTS

Infants under 12 months old who were admitted from the emergency department with bronchiolitis between January 1, 2010, and December 31, 2018.

MEASUREMENTS AND MAIN RESULTS

Primary outcomes were rates of noninvasive ventilation, invasive ventilation, and cardiac arrest. Trends over time were assessed with univariate logistic regression. In the main analysis, hospital-level multivariable logistic regression evaluated rates of outcomes including invasive ventilation and cardiac arrest among hospitals with high and low utilization of noninvasive ventilation. The study included 147,288 hospitalizations of infants with bronchiolitis. Across the entire study population, noninvasive and invasive ventilation increased between 2010 and 2018 (2.9-8.7%, 2.1-4.0%, respectively; p < 0·001). After adjustment for markers of severity of illness, hospital-level noninvasive ventilation (high vs low utilization) was not associated with differences in invasive ventilation (5.0%, 1.8%, respectively, adjusted odds ratio, 1.8; 95% CI, 0·7-4·6) but was associated with increased cardiac arrest (0.36%, 0.02%, respectively, adjusted odds ratio, 25.4; 95% CI, 4.9-131.0).

CONCLUSIONS

In a large cohort of infants at children's hospitals, noninvasive and invasive ventilation increased significantly from 2010 to 2018. Hospital-level noninvasive ventilation utilization was not associated with a reduction in invasive ventilation but was associated with higher rates of cardiac arrest even after controlling for severity. Noninvasive ventilation in bronchiolitis may incur an unintended higher risk of cardiac arrest, and this requires further investigation.

Paediatric ED BiPAP continuous quality improvement programme with patient analysis: 2005-2013

OBJECTIVE

In paediatric moderate-to-severe asthmatics, there is significant bronchospasm, airway obstruction, air trapping causing severe hyperinflation with more positive intraplural pressure preventing passive air movement. These effects cause an increased respiratory rate (RR), less airflow and shortened inspiratory breath time. In certain asthmatics, aerosols are ineffective due to their inadequate ventilation. Bilevel positive airway pressure (BiPAP) in acute paediatric asthmatics can be an effective treatment. BiPAP works by unloading fatigued inspiratory muscles, a direct bronchodilation effect, offsetting intrinsic PEEP and recruiting collapsed alveoli that reduces the patient's work of breathing and achieves their total lung capacity quicker. Unfortunately, paediatric emergency department (PED) BiPAP is underused and quality analysis is non-existent. A PED BiPAP Continuous Quality Improvement Program (CQIP) from 2005 to 2013 was evaluated using descriptive analytics for the primary outcomes of usage, safety, BiPAP settings, therapeutics and patient disposition.

INTERVENTIONS

PED BiPAP CQIP descriptive analytics.

SETTING

Academic PED.

PARTICIPANTS

1157 patients.

INTERVENTIONS

A PED BiPAP CQIP from 2005 to 2013 for the usage, safety, BiPAP settings, therapeutic response parameters and patient disposition was evaluated using descriptive analytics.

PRIMARY AND SECONDARY OUTCOMES

Safety, usage, compliance, therapeutic response parameters, BiPAP settings and patient disposition.

RESULTS

1157 patients had excellent compliance without complications. Only 6 (0.5%) BiPAP patients were intubated. BiPAP median settings: IPAP 18 (16,20) cm H₂O range 12-28; EPAP 8 cmH₂O (8,8) range 6-10; inspiratory-to-expiratory time (I:E) ratio 1.75 (1.5,1.75). Pediatric Asthma Severity score and RR decreased (p<0.001) while tidal volume increased (p<0.001). Patient disposition: 325 paediatric intensive care units (PICU), 832 wards, with 52 of these PED ward patients were discharged home with only 2 hours of PED BiPAP with no returning to the PED within 72 hours.

CONCLUSIONS

BiPAP is a safe and effective therapeutic option for paediatric patients with asthma presenting to a PED or emergency department. This BiPAP CQIP showed significant patient compliance, no complications, improved therapeutics times, very low intubations and decreased PICU admissions. CQIP analysis demonstrated that using a higher IPAP, low EPAP with longer I:E optimises the patient's BiPAP settings and showed a significant improvement in PAS, RR and tidal volume. BiPAP should be considered as an early treatment in the PED severe or non-responsive moderate asthmatics.

Severe subcutaneous emphysema and pneumomediastinum secondary to noninvasive ventilation support in status asthmaticus

A 12-year-old male with status asthmaticus developed subcutaneous emphysema and pneumomediastinum. He was transferred to our unit, where he received noninvasive ventilation (NIV). This respiratory support technique is not an absolute contraindication in these cases. After 2 h on NIV, he worsened sharply and the subcutaneous emphysema got bigger suddenly. He needed invasive ventilation for 5 days. Final outcome was satisfactory. This case illustrates that it is mandatory to keep a high level of vigilance when using NIV in patients with air leaks.

Anesthesia and ventilation strategies in children with asthma: part II - intraoperative management

PURPOSE OF REVIEW

As asthma is a frequent disease especially in children, anesthetists are increasingly providing anesthesia for children requiring elective surgery with well controlled asthma but also for those requiring urgent surgery with poorly controlled or undiagnosed asthma. This second part of this two-part review details the medical and ventilatory management throughout the perioperative period in general but also includes the perioperative management of acute bronchospasm and asthma exacerbations in children with asthma.

RECENT FINDINGS

Multiple observational trials assessing perioperative respiratory adverse events in healthy and asthmatic children provide the basis for identifying risk reduction strategies. Mainly, animal experiments and to a small extent clinical data have advanced our understanding of how anesthetic agents effect bronchial smooth muscle tone and blunt reflex bronchoconstriction. Asthma treatment outside anesthesia is well founded on a large body of evidence.Perioperative prevention strategies have increasingly been studied. However, evidence on the perioperative management, including mechanical ventilation strategies of asthmatic children, is still only fair, and further research is required.

SUMMARY

To minimize the considerable risk of perioperative respiratory adverse events in asthmatic children, perioperative management should be based on two main pillars: the preoperative optimization of asthma treatment (please refer to the first part of this two-part review) and - the focus of this second part of this review - the optimization of anesthesia management in order to optimize lung function and minimize bronchial hyperreactivity in the perioperative period.

Non-invasive ventilation in pediatric status asthmaticus: a prospective observational study

OBJECTIVE

Non-invasive ventilation (NIV) has been shown to be effective in different causes of respiratory failure in both adult and pediatric patients. However, its role in status asthmaticus (SA) remains unclear. We designed a prospective study to assess the feasibility of NIV in children with SA.

STUDY DESIGN

Prospective observational study, over a 4.5-year period.

PATIENT SELECTION

Children with SA unresponsive to conventional therapy with a modified Wood's clinical asthma score (m-WCAS) ≥4 and marked increased work of breathing, were included.

METHODOLOGY

Patients were placed on pressure support NIV. During NIV therapy, salbutamol was nebulized continuously and ipratropium bromide every 2 hr; methyl-prednisolone was given at a dose of 1-2 mg/kg/6 hr. Clinical variables were measured at baseline and at 1, 6, 12, 24, and 48 hr.

RESULTS

During the study period, there were 122 PICU admissions due to SA; 72 episodes fulfilled inclusion criteria. Baseline mean values were as follows: m-WCAS of 5.7 points, heart rate (HR) of 166.7 beats/min, respiratory rate (RR) of 49.5 breaths/min and FiO(2) of 45.3%. In the first hour m-WCAS fell 2.3 ± 1.5 points, HR 13.5 ± 14 beats/min, and RR 9.8 ± 10 breaths/min (P < 0.01). After institution of NIV therapy, 5 children required intubation due to increasing respiratory distress. There was one case of massive subcutaneous emphysema, with no other serious adverse effects associated with NIV.

CONCLUSIONS

These results show that NIV is a feasible therapy in children with SA unresponsive to conventional treatment. Pediatr. Pulmonol. 2011; 46:949-955. © 2011 Wiley-Liss, Inc.

Acute severe asthma: new approaches to assessment and treatment

The precise definition of a severe asthmatic exacerbation is an issue that presents difficulties. The term 'status asthmaticus' relates severity to outcome and has been used to define a severe asthmatic exacerbation that does not respond to and/or perilously delays the repetitive or continuous administration of short-acting inhaled beta(2)-adrenergic receptor agonists (SABA) in the emergency setting. However, a number of limitations exist concerning the quantification of unresponsiveness. Therefore, the term 'acute severe asthma' is widely used, relating severity mostly to a combination of the presenting signs and symptoms and the severity of the cardiorespiratory abnormalities observed, although it is well known that presentation does not foretell outcome. In an acute severe asthma episode, close observation plus aggressive administration of bronchodilators (SABAs plus ipratropium bromide via a nebulizer driven by oxygen) and oral or intravenous corticosteroids are necessary to arrest the progression to severe hypercapnic respiratory failure leading to a decrease in consciousness that requires intensive care unit (ICU) admission and, eventually, ventilatory support. Adjunctive therapies (intravenous magnesium sulfate and/or others) should be considered in order to avoid intubation. Management after admission to the hospital ward because of an incomplete response is similar. The decision to intubate is essentially based on clinical judgement. Although cardiac or respiratory arrest represents an absolute indication for intubation, the usual picture is that of a conscious patient struggling to breathe. Factors associated with the increased likelihood of intubation include exhaustion and fatigue despite maximal therapy, deteriorating mental status, refractory hypoxaemia, increasing hypercapnia, haemodynamic instability and impending coma or apnoea. To intubate, sedation is indicated in order to improve comfort, safety and patient-ventilator synchrony, while at the same time decrease oxygen consumption and carbon dioxide production. Benzodiazepines can be safely used for sedation of the asthmatic patient, but time to awakening after discontinuation is prolonged and difficult to predict. The most common alternative is propofol, which is attractive in patients with sudden-onset (near-fatal) asthma who may be eligible for extubation within a few hours, because it can be titrated rapidly to a deep sedation level and has rapid reversal after discontinuation; in addition, it possesses bronchodilatory properties. The addition of an opioid (fentanyl or remifentanil) administered by continuous infusion to benzodiazepines or propofol is often desirable in order to provide amnesia, sedation, analgesia and respiratory drive suppression. Acute severe asthma is characterized by severe pulmonary hyperinflation due to marked limitation of the expiratory flow. Therefore, the main objective of the initial ventilator management is 2-fold: to ensure adequate gas exchange and to prevent further hyperinflation and ventilator-associated lung injury. This may require hypoventilation of the patient and higher arterial carbon dioxide (PaCO(2)) levels and a more acidic pH. This does not apply to asthmatic patients intubated for cardiac or respiratory arrest. In this setting the post-anoxic brain oedema might demand more careful management of PaCO(2) levels to prevent further elevation of intracranial pressure and subsequent complications. Monitoring lung mechanics is of paramount importance for the safe ventilation of patients with status asthmaticus. The first line of specific pharmacological therapy in ventilated asthmatic patients remains bronchodilation with a SABA, typically salbutamol (albuterol). Administration techniques include nebulizers or metered-dose inhalers with spacers. Systemic corticosteroids are critical components of therapy and should be administered to all ventilated patients, although the dose of systemic corticosteroids in mechanically ventilated asthmatic patients remains controversial. Anticholinergics, inhaled corticosteroids, leukotriene receptor antagonists and methylxanthines offer little benefit, and clinical data favouring their use are lacking. In conclusion, expertise, perseverance, judicious decisions and practice of evidence-based medicine are of paramount importance for successful outcomes for patients with acute severe asthma.