Efficacy, results, and complications of mechanical ventilation in children with status asthmaticus

Children with Near-Fatal Asthma: The Use of Inhaled Volatile Anesthetics and Extracorporeal Membrane Oxygenation

Background and Purpose: The use of extracorporeal membrane oxygenation (ECMO) has been described for near-fatal asthma that continues to be refractory despite maximal medical therapy. Methods: Patients admitted to the pediatric intensive care unit at Texas Children's Hospital from 2012 to 2020 with the diagnosis of asthma who were supported on ECMO or isoflurane were included in the study. Patient demographics, medication usage, and complications were compared between the case group (ECMO, n = 12) and the control group (isoflurane only, n = 8). Results: All patients survived to discharge. ECMO patients received shorter durations of albuterol (12 versus 104 h, P = 0.0002) and terbutaline (13.3 versus 31.5 h, P = 0.0250). There were no differences in complication rates between the 2 groups. Conclusion: ECMO is a reasonable and safe support method for patients with near-fatal asthma and may lead to less bronchodilator medication exposure when compared with inhaled volatile anesthetic use.

Anesthetic considerations in children with asthma

Due to the high prevalence of asthma and general airway reactivity, anesthesiologists frequently encounter children with asthma or asthma-like symptoms. This review focuses on the epidemiology, the underlying pathophysiology, and perioperative management of children with airway reactivity, including controlled and uncontrolled asthma. It spans from preoperative optimization to optimized intraoperative management, airway management, and ventilation strategies. There are three leading causes for bronchospasm (1) mechanical (eg, airway manipulation), (2) non-immunological anaphylaxis (anaphylactoid reaction), and (3) immunological anaphylaxis. Children with increased airway reactivity may benefit from a premedication with beta-2 agonists, non-invasive airway management, and deep removal of airway devices. While desflurane should be avoided in pediatric anesthesia due to an increased risk of bronchospasm, other volatile agents are potent bronchodilators. Propofol is superior in blunting airway reflexes and, therefore, well suited for anesthesia induction in children with increased airway reactivity.

Emergency department treatment of asthma in children: A review

Asthma is the most common chronic illness in children, with >700,000 emergency department (ED) visits each year. Asthma is a respiratory disease characterized by a combination of airway inflammation, bronchoconstriction, bronchial hyperresponsiveness, and variable outflow obstruction, with clinical presentations ranging from mild to life-threatening. Standardized ED treatment can improve patient outcomes, including fewer hospital admissions. Informed by the most recent guidelines, this review focuses on the optimal approach to diagnosis and treatment of children with acute asthma exacerbations who present to the ED.

Contemporary treatment of children with critical and near-fatal asthma

Asthma is the most common chronic illness in childhood. Although the vast majority of children with acute asthma exacerbations do not require critical care, some fail to respond to standard treatment and require escalation of support. Children with critical or near-fatal asthma require close monitoring for deterioration and may require aggressive treatment strategies. This review examines the available evidence supporting therapies for critical and near-fatal asthma and summarizes the contemporary clinical care of these children. Typical treatment includes parenteral corticosteroids and inhaled or intravenous beta-agonist drugs. For children with an inadequate response to standard therapy, inhaled ipratropium bromide, intravenous magnesium sulfate, methylxanthines, helium-oxygen mixtures, and non-invasive mechanical support can be used. Patients with progressive respiratory failure benefit from mechanical ventilation with a strategy that employs large tidal volumes and low ventilator rates to minimize dynamic hyperinflation, barotrauma, and hypotension. Sedatives, analgesics and a neuromuscular blocker are often necessary in the early phase of treatment to facilitate a state of controlled hypoventilation and permissive hypercapnia. Patients who fail to improve with mechanical ventilation may be considered for less common approaches, such as inhaled anesthetics, bronchoscopy, and extracorporeal life support. This contemporary approach has resulted in extremely low mortality rates, even in children requiring mechanical support.

Evaluation and treatment of critical asthma syndrome in children

The heterogeneity of asthma is illustrated by the significantly different features of pediatric asthma compared to adult asthma. One phenotype of severe asthma in pediatrics includes atopy, lack of reduction in lung function, and absence of gender bias as the main characteristics. Included in the NIH NAEPP EPR-3 are recommendations for the treatment and management of severe pediatric asthma and critical asthma syndrome, such as continuous nebulization treatments, intubation and mechanical ventilation, heliox, and magnesium sulfate. In addition, epinephrine, intravenous immunoglobulin, intravenous montelukast, extracorporeal membrane oxygenation, and many biological modulators currently under investigation are additional current and/or future treatment modalities for the severe pediatric asthmatic. But, perhaps the most important strategy for managing the severe asthmatic is preventative treatment, which can significantly decrease impairment and risk, particularly for severe acute exacerbations requiring emergency care and/or hospitalization. In order for preventative therapy to be successful, several challenges must be met, including selecting the correct therapy for each patient and then ensuring compliance or adherence to a treatment plan. The heterogeneity of asthma renders the former difficult in that not all patients will respond equally to the same treatment; the latter is only helpful if the correct treatment is employed. Strategies to ensure compliance include education of caregivers and patients and their families. As newer medications are introduced, options for individualized or customized medicine increase, and this may pave the way for significant decreases in morbidity and mortality in severe pediatric asthma.

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.

Anesthesia and ventilation strategies in children with asthma: part I - preoperative assessment

PURPOSE OF REVIEW

Asthma is a common disease in the pediatric population, and anesthetists are increasingly confronted with asthmatic children undergoing elective surgery. This first of this two-part review provides a brief overview of the current knowledge on the underlying physiology and pathophysiology of asthma and focuses on the preoperative assessment and management in children with asthma. This also includes preoperative strategies to optimize lung function of asthmatic children undergoing surgery. The second part of this review focuses on the immediate perioperative anesthetic management including ventilation strategies.

RECENT FINDINGS

Multiple observational trials assessing perioperative respiratory adverse events in healthy and asthmatic children provide the basis for identifying risk factors in the patient's (family) history that aid the preoperative identification of at-risk children. Asthma treatment outside anesthesia is well founded on a large body of evidence. Optimization and to some extent intensifying asthma treatment can optimize lung function, reduce bronchial hyperreactivity, and minimize the risk of perioperative respiratory adverse events.

SUMMARY

To minimize the considerable risk of perioperative respiratory adverse events in asthmatic children, a good understanding of the underlying physiology is vital. Furthermore, a thorough preoperative assessment to identify children who may benefit of an intensified medical treatment thereby minimizing airflow obstruction and bronchial hyperreactivity is the first pillar of a preventive perioperative management of asthmatic children. The second pillar, an individually adjusted anesthesia management aiming to reduce perioperative adverse events, is discussed in the second part of this review.

Outcomes of invasive mechanical ventilation in children and adolescents hospitalized due to status asthmaticus in United States: a population based study

OBJECTIVE

Current national estimates of and outcomes of Invasive Mechanical Ventilation (MV) in status asthmaticus (SA) are unclear. The objective of this study is to estimate the incidence and outcomes of MV in hospitalized SA children and adolescents.

METHODS

We used the Nationwide Inpatient Sample (NIS, 2009-2010), the largest all-payer hospital discharge database in United States. All hospitalizations (age ≤21 years) with a primary diagnosis of SA were selected. MV was identified using ICD-9-CM procedure codes. Multivariable regression analyses were used to examine the association between MV and outcomes (Length of Stay (LOS) and Hospital Charges (HC)).

RESULTS

Over the study period, of the 250 718 SA hospitalizations, MV was needed for <96 h in 0.37% hospitalizations and 0.18% had MV for ≥96 h. Complications occurred in 12.4% (30 991) of all hospitalizations with pneumonia (10.8%) being the most common. A total of 65 patients died in hospitals (the overall in-hospital mortality [IHM] rate was 0.03%). About 55 of these deaths occurred among those who had MV (4% IHM rate for those receiving MV). The mean LOS and hospital HC included without MV (2.1 d, $11 921) MV < 96 h (4.8 d, $52 201); MV > 96 h (15.6 d, $200 336). After adjustment for patient/hospital level factors, the need for MV was associated with significantly higher LOS and HC (p < 0.0001). Those who had MV<96 h (OR = 2.58, 95% CI = 1.77-3.77) or MV ≥ 96 h (OR = 6.23, 95% CI = 3.87-10.03) had higher risk of developing pneumonia.

CONCLUSIONS

Although MV is infrequently needed in children and adolescents hospitalized for SA (0.55% incidence rate), it is associated with higher IHM rate and significant hospital resource utilization.

Association of center volume with outcomes in critically ill children with acute asthma

BACKGROUND

Little is known about the relation between center volume and outcomes in children requiring intensive care unit (ICU) admission for acute asthma.

OBJECTIVE

To evaluate the association of center volume with the odds of receiving positive pressure ventilation and length of ICU stay.

METHODS

Patients 2 to 18 years of age with the primary diagnosis of asthma were included (2009-2012). Center volume was defined as the average number of mechanical ventilator cases per year for any diagnoses during the study period. In multivariable analysis, the odds of receiving positive pressure ventilation (invasive and noninvasive ventilation) and ICU length of stay were evaluated as a function of center volume.

RESULTS

Fifteen thousand eighty-three patients from 103 pediatric ICUs with the primary diagnosis of acute asthma met the inclusion criteria. Seven hundred fifty-two patients (5%) received conventional mechanical ventilation and 964 patients (6%) received noninvasive ventilation. In multivariable analysis, center volume was not associated with the odds of receiving any form of positive pressure ventilation in children with acute asthma, with the exception of high- to medium-volume centers. However, ICU length of stay varied with center volume and was noted to be longer in low-volume centers compared with medium- and high-volume centers.

CONCLUSION

In children with acute asthma, this study establishes a relation between center volume and ICU length of stay. However, this study fails to show any significant relation between center volume and the odds of receiving positive pressure ventilation; further analyses are needed to evaluate this relation in more detail.

Pediatric fiberoptic bronchoscopy as adjunctive therapy in acute asthma with respiratory failure

BACKGROUND

Status asthmaticus respiratory failure is associated with thickened mucus secretions necessitating aggressive pulmonary clearance. The role of bronchoscopy in pediatric mechanically ventilated asthmatic patients has not been published.

METHODS

A chart review was performed on all pediatric intensive care unit (PICU) asthmatics with respiratory failure over 13 years. Forty-four patients were identified. Patients were managed per standardized guidelines for status asthmaticus with mechanical ventilation. Ventilator management prioritized spontaneous breathing with pressure support. Extubation criteria included spontaneous tidal volumes of 5-7 cm(3) /kg on low-pressure support. Standard endotracheal tube pulmonary toilet were implemented. Twenty-nine patients underwent bronchoscopy as an adjunctive therapy. Indications for bronchoscopy included: Pathogen identification via bronchoalveolar ravage, atelectasis, mucus obstruction resulting in severe air trapping, suspected aspiration, and poor response to standard therapy. Clinical outcomes of this intervention were compared to the fifteen patient cohort who did not undergo bronchoscopy.

RESULTS

Bronchoscopies revealed thick mucus plugs, secretions, and bronchial casts. The large airways were lavaged for clearance of obstructive secretions with normal saline. All patients tolerated the procedure without any complications. Demonstrable improvement in pulmonary compliance was noted. The median time of intubation for the bronchoscopy group was 10 hr compared to 20.5 hr for the control group (P < 0.0005). The mean intensive care unit length of stay was 3.06 days for the bronchoscopy group versus 3.4 days for the non-bronchoscopy group (P < 0.05).

CONCLUSION

Flexible bronchoscopy with bronchial lavage is a safe adjunctive therapy in pediatric asthmatics with respiratory failure resulting in reduced mechanical ventilation and intensive care length of stay. Restoring lung volume in certain asthmatics during respiratory failure may be deemed beneficial. Further validated studies are necessary to recommend bronchoscopy to the present, accepted treatment regimen in pediatric asthmatic respiratory failure.

Fatal and near-fatal asthma in children: the critical care perspective

OBJECTIVE

To characterize the clinical course, therapies, and outcomes of children with fatal and near-fatal asthma admitted to pediatric intensive care units (PICUs).

STUDY DESIGN

This was a retrospective chart abstraction across the 8 tertiary care PICUs of the Collaborative Pediatric Critical Care Research Network (CPCCRN). Inclusion criteria were children (aged 1-18 years) admitted between 2005 and 2009 (inclusive) for asthma who received ventilation (near-fatal) or died (fatal). Data collected included medications, ventilator strategies, concomitant therapies, demographic information, and risk variables.

RESULTS

Of the 261 eligible children, 33 (13%) had no previous history of asthma, 218 (84%) survived with no known complications, and 32 (12%) had complications. Eleven (4%) died, 10 of whom had experienced cardiac arrest before admission. Patients intubated outside the PICU had a shorter duration of ventilation (median, 25 hours vs 84 hours; P < .001). African-Americans were disproportionately represented among the intubated children and had a shorter duration of intubation. Barotrauma occurred in 15 children (6%) before admission. Pharmacologic therapy was highly variable, with similar outcomes.

CONCLUSION

Of the children ventilated in the CPCCRN PICUs, 96% survived to hospital discharge. Most of the children who died experienced cardiac arrest before admission. Intubation outside the PICU was correlated with shorter duration of ventilation. Complications of barotrauma and neuromyopathy were uncommon. Practice patterns varied widely among the CPCCRN sites.

Common pediatric respiratory emergencies

Pediatric respiratory illnesses are a huge burden to emergency departments worldwide. This article reviews the latest evidence in the epidemiology, assessment, management, and disposition of children presenting to the emergency department with asthma, croup, bronchiolitis, and pneumonia.

The increased cost of complications in children with status asthmaticus

Status asthmaticus is one of the most common causes of admission to a pediatric intensive care unit (PICU). There is little published data, however, examining the complications associated with the treatment of status asthmaticus in children in the PICU. Our hypothesis was that children experiencing a complication would have an increased duration of hospitalization for status asthmaticus. We performed a retrospective review of the complication profile and hospital course of all children admitted to a PICU with status asthmaticus over a 9 years period. Twenty-two (8%) of the 293 children admitted to the ICU with status asthmaticus experienced one or more complications during their treatment. The most common complications were aspiration pneumonia, ventilator-associated pneumonia, pneumomediastinum, pneumothorax, and rhabdomyolysis. Intubated children were significantly more likely than non-intubated children to experience a complication (RR 15.3; 95% CI 6.7-35). Fifteen (42%) of the 36 intubated children experienced a complication. Intubated children experiencing a complication had significantly longer duration of mechanical ventilation (163 +/- 169 hr vs. 66 +/- 65 hr, P = 0.03), ICU length of stay (237 +/- 180 hr vs. 124 +/- 86 hr, P = 0.02) and hospital charges (US dollars 117,184 +/- 111,191 vs. US dollars 38,788 +/- 27,784; P = 0.001) than intubated children not experiencing a complication. In this review, complications were associated with increased morbidity and duration of hospitalization in children with status asthmaticus, particularly in those intubated as part of their therapy. This suggests that intubation and mechanical ventilation itself may increase the risk of developing a complication in this population.

Endotracheal intubation and pediatric status asthmaticus: site of original care affects treatment

OBJECTIVES

Status asthmaticus is a common cause of admission to a pediatric intensive care unit (PICU). Children unresponsive to medical therapies may require endotracheal intubation; however, this treatment carries significant risk, and thresholds for intubation vary. Our hypothesis was that children who sought care at community hospitals received less aggressive treatment and more frequent intubation than children who sought care at a children's hospital.

DESIGN

Retrospective cohort study.

SETTING

A university-affiliated children's hospital PICU.

PATIENTS

We retrospectively examined data from all children older than 2 yrs admitted to the PICU with status asthmaticus between April 1997 and July 2005.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Of the 251 children admitted to the PICU with status asthmaticus, 130 initially presented to the emergency department of a children's hospital and 116 presented to the emergency department of a community hospital. Despite similar illness severity, children presenting to a community hospital were significantly more likely to be intubated than those presenting to a children's hospital (17% vs. 5%; p = .004). In addition, those children intubated at community hospitals were intubated sooner after presentation (2.4 +/- 5.2 vs. 7.5 +/- 5.8 hrs; p = .009), had shorter durations of intubation (71 +/- 73 vs. 151 +/- 81 hrs; p = .02), and had shorter PICU length of stays (129 +/- 82 vs. 230 +/- 84 hrs; p = .01).

CONCLUSIONS

Children with status asthmaticus are more likely to be intubated, and intubated sooner, at a community hospital. The shorter duration of intubation suggests that some children may not have been intubated had they presented to a children's hospital or received more aggressive therapy at their community hospital.

Ketamine to avoid mechanical ventilation in severe pediatric asthma

Children experiencing severe asthma exacerbations may deteriorate to respiratory failure requiring endotracheal intubation and mechanical ventilation. Mechanical ventilation is often life saving in this setting, but also exposes the asthmatic child to substantial iatrogenic risk. We present two cases of severe asthma exacerbations in prepubertal children for whom the administration of a bolus of intravenous ketamine followed by a continuous infusion of a relatively large dose of ketamine led to prompt improvement, obviating the need for mechanical ventilation. These cases suggest that for children experiencing severe asthma exacerbations, intravenous ketamine may be an effective temporizing measure to avoid exposing these children to the risks associated with mechanical ventilation.

Duration of mechanical ventilation in life-threatening pediatric asthma: description of an acute asphyxial subgroup

OBJECTIVE

Acute asphyxial asthma (AAA) is well described in adult patients and is characterized by a sudden onset that may rapidly progress to a near-arrest state. Despite the initial severity of AAA, mechanical ventilation often restores gas exchange promptly, resulting in shorter durations of ventilation. We believe that AAA can occur in children and can lead to respiratory failure that requires mechanical ventilation. Furthermore, children with rapid-onset respiratory failure that requires intubation in the emergency department (ED) are more likely to have AAA and a shorter duration of mechanical ventilation than those intubated in the pediatric intensive care unit (PICU).

METHODS

An 11-year retrospective chart review (1991-2002) was conducted of all children who were aged 2 through 18 years and had the primary diagnosis of status asthmaticus and required mechanical ventilation.

RESULTS

During the study period, 33 (11.4%) of 290 PICU admissions for status asthmaticus required mechanical ventilation. Thirteen children presented with rapid respiratory failure en route, on arrival, or within 30 minutes of arrival to the ED versus 20 children who progressed to respiratory failure later in their ED course or in the PICU. Mean duration of mechanical ventilation was significantly shorter in the children who presented with rapid respiratory failure versus those with progressive respiratory failure (29 +/- 43 hours vs 88 +/- 72 hours). Children with rapid respiratory failure had greater improvements in ventilation and oxygenation than those with progressive respiratory failure as measured by pre- and postintubation changes in arterial carbon dioxide pressure, arterial oxygen pressure/fraction of inspired oxygen ratio, and alveolar-arterial gradient. According to site of intubation, 23 children required intubation in the ED, whereas 10 were intubated later in the PICU. Mean duration of mechanical ventilation was significantly shorter in the ED group versus the PICU group (42 +/- 63 hours vs 118 +/- 46 hours). There were significantly greater improvements in ventilation and oxygenation in the ED group versus the PICU group as measured by pre- and postintubation changes in arterial carbon dioxide pressure and arterial oxygen pressure/fraction of inspired oxygen ratio.

CONCLUSIONS

AAA occurs in children and shares characteristics seen in adult counterparts. Need for early intubation is a marker for AAA and may not represent a failure to maximize preintubation therapies. AAA represents a distinct form of life-threatening asthma and requires additional study in children.

Pressure-controlled ventilation in children with severe status asthmaticus

OBJECTIVE

The optimum strategy for mechanical ventilation in a child with status asthmaticus is not established. Volume-controlled ventilation continues to be the traditional approach in such children. Pressure-controlled ventilation may be theoretically more advantageous in allowing for more uniform ventilation. We describe our experience with pressure-controlled ventilation in children with severe respiratory failure from status asthmaticus.

DESIGN

Retrospective review.

SETTING

Pediatric intensive care unit in a university-affiliated children's hospital.

PATIENTS

All patients who received mechanical ventilation for status asthmaticus.

INTERVENTIONS

Pressure-controlled ventilation was used as the initial ventilatory strategy. The optimum pressure control, rate, and inspiratory and expiratory time were determined based on blood gas values, flow waveform, and exhaled tidal volume.

MEASUREMENT AND MAIN RESULTS

Forty patients were admitted for 51 episodes of severe status asthmaticus requiring mechanical ventilation. Before the institution of pressure-controlled ventilation, median pH and Pco(2) were 7.21 (range, 6.65-7.39) and 65 torr (29-264 torr), respectively. Four hours after pressure-controlled ventilation, median pH increased to 7.31 (6.98-7.45, p <.005), and Pco(2) decreased to 41 torr (21-118 torr, p <.005). For patients with respiratory acidosis (Pco(2) >45 torr) within 1 hr of starting pressure-controlled ventilation, the median length of time until Pco(2) decreased to <45 torr was 5 hrs (1-51 hrs). Oxygen saturation was maintained >95% in all patients. Two patients had pneumomediastinum before pressure-controlled ventilation. One patient each developed pneumothorax and subcutaneous emphysema after initiation of pressure-controlled ventilation. All patients survived without any neurologic morbidity. Median duration of mechanical ventilation was 29 hrs (4-107 hrs), intensive care stay was 56 hrs (17-183 hrs), and hospitalization was 5 days (2-20 days).

CONCLUSIONS

Based on this retrospective study, we suggest that pressure-controlled ventilation is an effective ventilatory strategy in severe status asthmaticus in children. Pressure-controlled ventilation represents a therapeutic option in the management of such children.

Helium-oxygen therapy for pediatric acute severe asthma requiring mechanical ventilation

OBJECTIVE

To illustrate the use of helium-oxygen gas mixtures as therapy for pediatric patients with acute severe asthma requiring conventional mechanical ventilation.

DESIGN

Retrospective review.

SETTING

Tertiary care children's teaching hospital.

PATIENTS

All mechanically ventilated patients with severe asthma admitted to the pediatric intensive care unit from August 1994 to October 2000.

INTERVENTIONS

Within 24 hrs of intubation or admission, patients were stabilized on volume ventilation, bronchodilator therapy, corticosteroids, and antibiotics when indicated. Hypercapnia was permitted while maintaining arterial blood gas pH > or =7.25. A helium-oxygen gas mixture then was begun with helium flow set at 5-7 L/min, and oxygen flow was titrated to maintain desired oxygen saturation. Only sedated, chemically paralyzed patients with adequate pre-helium-oxygen and post-helium-oxygen measurements were statistically analyzed.

MEASUREMENTS AND MAIN RESULTS

Twenty-eight mechanically ventilated patients with severe asthma placed on helium-oxygen gas mixtures were identified who met study entry criteria. Mean patient age was 8.8 yrs (range, 1.1-14.6). Before helium-oxygen therapy began, mean peak inspiratory pressure was 40.5 +/- 4.2 cm H(2)O, mean arterial blood gas pH was 7.26 +/- 0.05, and mean CO(2) partial pressure was 58.2 +/- 8.5 torr. After patients were placed on helium-oxygen therapy, there was a significant decrease in mean peak inspiratory pressure to 35.3 +/- 3.0 cm H(2)O. Mean pH increased significantly to 7.32 +/- 0.06, and mean partial pressure CO(2) decreased significantly to 50.5 +/- 7.4 torr. Initial mean inspired helium was 57 +/- 4% (range, 32-74). Mechanical ventilation days ranged from 1 to 23 days (mean, 5.0). Hospital stay ranged from 4 to 29 days (mean, 10.1), with an average pediatric intensive care unit stay of 6.9 days (range, 2-24). There were two incidences of pneumothorax.

CONCLUSIONS

In the pediatric patient with severe asthma requiring conventional mechanical ventilation, helium-oxygen administration appears to be a safe therapy and may assist in lowering peak inspiratory pressure and improving blood gas pH and partial pressure CO(2).

Acute severe asthma: differences in therapies and outcomes among pediatric intensive care units

OBJECTIVE

To determine differences in therapies and outcomes among pediatric intensive care units for patients with acute severe asthma.

DESIGN

Retrospective cohort study.

SETTING

Eleven pediatric intensive care units participating in the Pediatric Intensive Care Evaluations.

PATIENTS

Patients were 1528 children with a primary diagnosis of asthma.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We studied severity of illness, length of stay, and use of invasive interventions. The patients at the centers had similar median physiologic measures of illness and Pediatric Risk of Mortality III scores. The patients received a wide range of invasive interventions depending on institution, including mechanical ventilation (3% to 47%), arterial catheter placement (4% to 46%), central venous catheter (2% to 51%), and determination of a blood gas (24% to 70%). At institutions where mechanical ventilation was used more commonly (>20%, high use), intensive care and hospital stays were longer for asthmatic patients regardless of mechanical ventilation requirement compared with centers with lower use of mechanical ventilation. The status of "high-use center" was an independent predictor for intensive care stay (p = .005) and hospital length of stay (p = .017) as well as duration of mechanical ventilation (p = .014) after adjustment for age, degree of hypercarbia, maximal respiratory rate, use of an arterial catheter, and Pediatric Risk of Mortality III scores among ventilated children.

CONCLUSIONS

We found that use of invasive interventions including mechanical ventilation and vascular monitoring varied greatly by institution. Centers with higher use of mechanical ventilation had longer median intensive care stay and hospital stays. Pediatric asthma management for acute severe asthma may be improved by clear elucidation of the institutional practices where fewer invasive interventions were used to achieve better outcomes.

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.

Randomised controlled trial of aminophylline for severe acute asthma

OBJECTIVES

To determine whether children with severe acute asthma treated with large doses of inhaled salbutamol, inhaled ipratropium, and intravenous steroids are conferred any further benefits by the addition of aminophylline given intravenously.

STUDY DESIGN

Randomised, double blind, placebo controlled trial of 163 children admitted to hospital with asthma who were unresponsive to nebulised salbutamol.

RESULTS

The placebo and treatment groups of children were similar at baseline. The 48 children in the aminophylline group had a greater improvement in spirometry at six hours and a higher oxygen saturation in the first 30 hours. Five subjects in the placebo group were intubated and ventilated after enrollment compared with none in the aminophylline group.

CONCLUSIONS

Aminophylline continues to have a place in the management of severe acute asthma in children unresponsive to initial treatment.

Treatment of critical status asthmaticus in children

Status asthmaticus is complex in its etiology and pathophysiology and may be associated with significant morbidity and mortality. Although there are many therapeutic options, specific inhaled beta 2-agonists, corticosteroids, and oxygen remain the mainstay of therapy. Several new drugs and some older drugs are being used in management; their exact role in treatment at present, however, relies largely on personal preferences. Innovative methods of providing ventilatory support are also emerging. What is quite clear is the fact that involvement of specialists (pulmonologists and intensivists) early in the course of severe status asthmaticus is needed to ensure optimal management and possibly favorable outcomes.