Low-dose beta-agonist continuous nebulization therapy for status asthmaticus in children

Fugitive aerosols in the intensive care unit: a narrative review

The risk of unintended inhalation of fugitive aerosols is becoming a topic of increasing interest in the healthcare arena. These fugitive aerosols may be bioaerosols, generated by the patient themselves through cough or sneeze, or they may be therapeutic medical aerosols, generated by therapeutic medical aerosol generators with the intent of delivery to a specific patient's respiratory tract. This review focus' on therapeutic aerosols in the intensive care unit (ICU) only, those typically generated by nebulisers. In the intensive care environment, patients are generally in receipt of ventilatory support, and the literature suggests that these different support interventions influence fugitive therapeutic medical aerosol emissions in a variety of ways. Predominant ventilatory support interventions include, but are not limited to, invasive mechanical ventilation (MV), non-invasive mechanical ventilation (NIV), high flow nasal therapy (HFNT), and supplemental oxygen delivery in spontaneously breathing patients. Further, factors such as nebuliser type, patient interface, patient breathing pattern, nebuliser position in the patient breathing circuit and medication formulation characteristics also have been shown to exert influence on aerosol concentrations and distance from the source. Here we present the state of the art knowledge in this, as yet, poorly described field of research, and identify the key risks, and subsequently, opportunities to mitigate the risks of unintended exposure of both patients and bystanders during and for periods following the administration of therapeutic aerosols.

Effect of high-dose continuous albuterol nebulization on clinical variables in children with status asthmaticus

OBJECTIVES

Continuous albuterol nebulization is generally administered at 2.5-20 mg/hr at most centers. We examined the effect of high-dose (75 or 150 mg/hr) albuterol on clinical variables in children with status asthmaticus.

DESIGN

Retrospective analysis of inpatient medical records and prospectively collected computerized PICU respiratory therapy database.

SETTING

Twenty-five-bed multidisciplinary PICU in a tertiary care children's hospital.

PATIENTS

Children admitted to the PICU between January 2006 and December 2007 with status asthmaticus receiving high-dose continuous albuterol nebulization. (Those with cerebral palsy, cardiac pathology, and ventilator dependence were excluded.)

INTERVENTIONS

: Chart review for PICU length of stay, albuterol dose, duration of nebulization, occurrence of chest pain, vomiting, tremors, hypokalemia (serum potassium < 3.0 mEq/L), and cardiac arrhythmia. Maximal heart rate, lowest diastolic blood pressure, and mean arterial pressure were compared to the variables at initiation of therapy and at hospital discharge.

MEASUREMENTS AND MAIN RESULTS

Forty-two patients (22 boys and 20 girls) received high-dose continuous albuterol nebulization. Twenty-three received 75 mg/hr and 19 received 150 mg/hr (3.7 mg/kg/hr [interquartile range, 2.4-5.8 mg/kg/hr]) for a duration of 22.3 hours (interquartile range, 6.6-31.7 hr). Heart rate increased and diastolic blood pressure and mean arterial pressure were significantly lower during nebulization compared to initiation of therapy or at hospital discharge (p < 0.05). No patient required fluid resuscitation or inotropic support, and one had self-limited premature ventricular contractions. Hypokalemia occurred in five of 33 patients who had serum electrolytes measured but did not require supplementation. One patient required endotracheal intubation after initiation of nebulization, and seven patients (16.7%) received noninvasive ventilation. PICU length of stay was 2.3 ± 1.7 days; there were no deaths.

CONCLUSIONS

High-dose continuous albuterol nebulization is associated with a low rate of subsequent mechanical ventilation and fairly short PICU length of stay without significant toxicity. Prospective studies comparing conventional and high-dose albuterol nebulization are needed to determine the optimum dose providing maximum efficacy with the least adverse effects.

Severe acute asthma exacerbation in children: a stepwise approach for escalating therapy in a pediatric intensive care unit

OBJECTIVES

An increasing prevalence of pediatric asthma has led to increasing burdens of critical illness in children with severe acute asthma exacerbations, often leading to respiratory distress, progressive hypoxia, and respiratory failure. We review the definitions, epidemiology, pathophysiology, and clinical manifestations of severe acute asthma, with a view to developing an evidence-based, stepwise approach for escalating therapy in these patients.

METHODS

Subject headings related to asthma, status asthmaticus, critical asthma, and drug therapy were used in a MEDLINE search (1980-2012), supplemented by a manual search of personal files, references cited in the reviewed articles, and treatment algorithms developed within Le Bonheur Children's Hospital.

RESULTS

Patients with asthma require continuous monitoring of their cardiorespiratory status via noninvasive or invasive devices, with serial clinical examinations, objective scoring of asthma severity (using an objective pediatric asthma score), and appropriate diagnostic tests. All patients are treated with β-agonists, ipratropium, and steroids (intravenous preferable over oral preparations). Patients with worsening clinical status should be progressively treated with continuous β-agonists, intravenous magnesium, helium-oxygen mixtures, intravenous terbutaline and/or aminophylline, coupled with high-flow oxygen and non-invasive ventilation to limit the work of breathing, hypoxemia, and possibly hypercarbia. Sedation with low-dose ketamine (with or without benzodiazepines) infusions may allow better toleration of non-invasive ventilation and may also prepare the patient for tracheal intubation and mechanical ventilation, if indicated by a worsening clinical status.

CONCLUSIONS

Severe asthma can be a devastating illness in children, but most patients can be managed by using serial objective assessments and the stepwise clinical approach outlined herein. Following multidisciplinary education and training, this approach was successfully implemented in a tertiary-care, metropolitan children's hospital.

Management of severe asthma exacerbation in children

BACKGROUND

Asthma is a common disease in children and acute severe asthma exacerbation can be life-threatening. This article aims to review recent advances in understanding of risk factors, pathophysiology, diagnosis and treatment of severe asthma exacerbation in children.

DATA SOURCES

Articles concerning severe asthma exacerbation in children were retrieved from PubMed. Literatures were searched with MeSH words "asthma", "children", "severe asthma exacerbation" and relevant cross references.

RESULTS

Severe asthma exacerbation in children requires aggressive treatments with β2-agonists, anticholinergics, and corticosteroids. Early initiation of inhaled β-agonists and systemic use of steroids are recommended. Other agents such as magnesium and aminophylline have some therapeutic benefits. When intubation and mechanical ventilation are needed, low tidal volume, controlled hypoventilation with lower-than-traditional respiratory rates and permissive hypercapnia can be applied.

CONCLUSIONS

Researchers should continue to detect the risk factors, pathophysiology, diagnosis and treatment of severe asthma exacerbation in children. More studies especially randomized controlled trials are required to evaluate the efficacy and safety of standard and new therapies.

Management of status asthmaticus in children

Asthma is a common chronic inflammatory disorder of the airways characterized by recurrent wheezing, breathlessness, and coughing. Acute exacerbations of asthma can be life-threatening; annual worldwide estimated mortality is 250,000 and most of these deaths are preventable. While most of the acute exacerbations can be managed successfully in the emergency room, few children have severe exacerbations requiring intensive care. Mainstay of treatment for status asthmaticus are inhaled β2 agonist and anticholinergic agents, oxygen along with corticosteroids. Children who do not respond well to initial treatment require parenteral β2 agonist and magnesium. Rarely, sick children need parenteral aminophylline infusion and mechanical ventilation. Guidelines for diagnosis, treatment, ventilator management and supportive care for status asthmaticus in children are discussed in the protocol.

Status asthmaticus in children

PURPOSE OF REVIEW

The prevalence of severe asthma in children has risen in the past few decades. The present review explores our current understanding of epidemiology, pathophysiology and treatment of status asthmaticus in children.

RECENT FINDINGS

The pathophysiology of inflammation and airway hyperactivity continues to be a source of research. Early initiation of inhaled beta-agonists and oral or parenteral steroids remain the standard of care in the treatment of status asthmaticus. Other treatment modalities such as magnesium and intravenous beta-agonists show some benefit. There is a resurgence of interest in the use of methylxanthines. Alternatives to endotracheal intubation show some promise in preventing respiratory failure.

SUMMARY

Asthma remains the third leading cause of hospitalization in children younger than 15 years old. Researchers continue to explore the efficacy of old and new treatment modalities. Future research efforts targeting at-risk populations could dramatically decrease asthma morbidity and mortality.

Beta2-agonists for asthma: the pediatric perspective

Inhaled beta-agonists are commonly prescribed for the treatment of wheezing disorders in infants and children. Despite this, there are concerns that these medications have potentially detrimental effects on lung health and symptoms. We will review the ontogeny of beta-agonist receptor and smooth muscle development from fetal life through infancy and childhood as well as the evidence supporting the clinical utility of beta-agonists in wheezing infants and asthmatic children. Finally, the potential detrimental effects of long- and short-acting beta-agonists in infants and children are discussed.

Respiratory distress

Preparation for pediatric pulmonary emergencies in the office setting includes adequate training for all medical staff, properly sized and working equipment, and medications to help alleviate respiratory distress when indicated. Status asthmaticus, viral bronchiolitis, and croup account for the vast majority of respiratory emergencies encountered in the pediatric office setting. Timely application of proven approaches to assessment and treatment of these illnesses can prevent hospitalization, decrease length of hospitalizations, and save lives.

Heliox administration in the pediatric intensive care unit: an evidence-based review

OBJECTIVE

To provide a comprehensive, evidence-based review of helium-oxygen gas mixtures (heliox) in the management of pediatric respiratory diseases.

DATA SOURCE

A thorough, computerized bibliographic search of the preclinical and clinical literature regarding the properties of helium and its application in pediatric respiratory disease states.

DATA SYNTHESIS

After an overview of the potential benefits and technical aspects of helium-oxygen gas mixtures, the role of heliox is addressed for asthma, aerosolized medication delivery, upper airway obstruction, postextubation stridor, croup, bronchiolitis, and high-frequency ventilation. The available data are objectively classified based on the value of the therapy or intervention as determined by the study design from which the data are obtained.

CONCLUSIONS

Heliox administration is most effective during conditions involving density-dependent increases in airway resistance, especially when used early in an acute disease process. Any beneficial effect of heliox should become evident in a relatively short period of time. The medical literature supports the use of heliox to relieve respiratory distress, decrease the work of breathing, and improve gas exchange. No adverse effects of heliox have been reported. However, heliox must be administered with vigilance and continuous monitoring to avoid technical complications.

Management of acute, severe asthma in children

OBJECTIVE

To briefly present the current options available for the treatment of acute, severe asthma in children, with a special focus on emergency department and inpatient treatment, and to describe newer therapies that may aid treatment in the future.

DATA SOURCES AND STUDY SELECTION

A MEDLINE search (1966-May 2001) of the English-language literature pertaining to drug therapy of acute asthma was performed. Key word searches included acute asthma, albuterol, ipratropium, corticosteroids, magnesium, and theophylline. Additional articles from these sources and published national guidelines were identified. Relevant studies pertaining to current therapy of acute asthma in pediatric patients were selected; if there were minimal pediatric data, adult data were included.

DATA SYNTHESIS

Asthma is a chronic, inflammatory disorder of the airways. Acute exacerbations can occur and are challenging to manage. Albuterol, ipratropium, and systemic corticosteroids have been shown to be effective in acute asthma exacerbations. Because some patients do not respond to maximal therapy, older therapies such as magnesium and theophylline are being reevaluated. Theophylline may have some therapeutic effect, but given its toxicity profile, it is unclear whether it offers any advantage over maximal beta(2)-agonist therapy. There are only minimal published data evaluating the use of magnesium in pediatrics, and most are small trials or case reports. Newer therapies such as ventilation strategies with heliox and intravenous leukotriene modifiers currently being evaluated may or may not prove to be beneficial in the future.

CONCLUSIONS

beta(2)-agonists, ipratropium, and corticosteroids remain the most useful therapeutic agents for acute asthma exacerbations in pediatric patients. However, these agents are not ideal in all patients and, given the existing questions regarding safety and/or efficacy of available alternatives, more effective options are needed.

Status asthmaticus in children: a review

About 10% of American children have asthma, and its prevalence, morbidity, and mortality have been increasing. Asthma is an inflammatory disease with edema, bronchial constriction, and mucous plugging. Status asthmaticus in children requires aggressive treatment with beta-agonists, anticholinergics, and corticosteroids. Intubation and mechanical ventilation should be avoided if at all possible, as the underlying dynamic hyperinflation will worsen with positive-pressure ventilation. If mechanical ventilation becomes necessary, controlled hypoventilation with low tidal volume and long expiratory time may lessen the risk of barotrauma and hypotension. Unusual and nonestablished therapies for severe asthma are discussed.

Acute asthma

OBJECTIVE: Asthma is the most common medical emergency in children. It is associated with significant morbidity and mortality rates and poses a tremendous societal burden worldwide. Management of the acute attack involves a stepwise approach that includes beta-agonist and steroid therapy, the mainstay of emergency treatment. Most patients will respond to this regime and can be discharged from the emergency department. Failure to respond to treatment necessitates hospital admission and sometimes admission to the intensive care unit (ICU). Management in the ICU involves intensification of pharmacologic therapy, including nonstandard therapies, in an attempt to avoid intubation and ventilation. When needed, mechanical ventilatory support can be rendered fairly safe with little morbidity if the likely cardiorespiratory physiologic derangements are appreciated and if appropriate ventilatory strategies are used. In the past two decades, the availability of newer potent medications and changes in approach to monitoring and ventilatory strategies have resulted in a decrease in ICU morbidity and mortality rates. Research endeavors are presently underway to further characterize the underlying mechanisms of the disease and are likely to lead to novel therapies. This article reviews the approach to management of acute severe asthma.

Continuously nebulized albuterol in severe exacerbations of asthma in adults: a case-controlled study

A retrospective, case-controlled analysis comparing patients admitted to a medical intensive care unit with severe exacerbations of asthma who received continuously nebulized albuterol (CNA) versus intermittent albuterol (INA) treatments is reported. Forty matched pairs of patients with asthma are compared. CNA was administered for a mean of 11 +/- 10 hr. The incidence of cardiac dysrhythmias was similar between groups. Symptomatic hypokalemia did not occur. CNA patients had higher heart rates during treatment, which may reflect severity of illness. The incidence of intubation was similar. We conclude that CNA and INA demonstrated similar profiles with regard to safety, morbidity, and mortality.

Alternatives to Standard Status Asthmaticus Therapy

Even with the currently available treatment, morbidity and mortality from asthma continues to rise. Patients with status asthmaticus who do not respond to standard therapy are at risk for respiratory failure and possible mechanical ventilation. Treatment options for refractory status asthmaticus remain limited and alternative and controversial therapies may need to be considered. Alternative therapies include continuous nebulized beta-agonists, ipratropium bromide, intravenous magnesium sulfate, ketamine, or heliox. Morbidity and mortality may be decreased by increased utilization of these alternative therapies. Pharmacists can play a key role in monitoring and recommending new and alternate therapies.

Continuous vs intermittent albuterol, at high and low doses, in the treatment of severe acute asthma in adults

Adult patients suffering from acute asthma presenting to the Emergency Department with an FEV1 of less than 40% of predicted were randomized into four treatment groups. They were treated with nebulized albuterol at a high (7.5 mg) or standard (2.5 mg) dose given either continuously through 1 h, or intermittently every hour, for 2 h. When the FEV1 improvements for the different groups at 2 h were compared, the groups treated with continuous nebulization had the greatest improvement. The improvements (1.07 L for the high-dose group, and 1.02 L for the standard-dose group) were significantly greater than the improvement seen with standard-dose intermittent treatment (0.72 L; p < 0.05). The improvement in FEV1 of the high-dose, hourly treated group was intermediate in magnitude between these (0.09 L). There was no difference in the improvement seen between the two groups treated with continuous nebulization. The potassium fall, present in all groups, was more pronounced in the groups treated with high doses of albuterol. Only one person (high dose, continuous treatment group) developed hypokalemia of less than 3.0 mmol/L. The high-dose hourly treated group had the highest incidence of side effects, and the standard-dose continuously treated group had the lowest. The standard-dose continuous-treatment regimen had the greatest improvement in FEV1 with the least number of side effects.