Aminophylline in the treatment of fluid overload

Effects of aminophylline therapy on urine output and kidney function in children with acute kidney injury

BACKGROUND

Acute kidney injury (AKI) is a frequent complication of children admitted to the paediatric intensive care unit. One key management modality of AKI is the use of diuretics to reduce fluid overload. Aminophylline, a drug that is well known for its use in the treatment of bronchial asthma, is also purported to have diuretic effects on the kidneys. This retrospective cohort study assesses the effect of aminophylline in critically ill children with AKI.

METHODS

A retrospective chart review of children admitted to the paediatric intensive care unit of the Red Cross War Memorial Children's Hospital (RCWMCH) with AKI who received aminophylline (from 2012 to June 2018) was carried out. Data captured and analyzed included demographics, underlying disease conditions, medications, urine output, fluid balance, and kidney function.

RESULTS

Data from thirty-four children were analyzed. Urine output increased from a median of 0.4 mls/kg/hr [IQR: 0.1, 1.1] at six hours prior to aminophylline administration to 0.6 mls/kg/hr [IQR: 0.2, 1.9] at six hours and 1.6 mls/kg/hr [IQR:0.2, 4.2] at twenty-four hours post aminophylline therapy. The median urine output significantly varied across the age groups over the 24-h time period post-aminophylline, with the most response in the neonates. There was no significant change in serum creatinine levels six hours post-aminophylline administration [109(IQR: 77, 227)-125.5(IQR: 82, 200) micromole/l] P-value = 0.135. However, there were significant age-related changes in creatinine levels at six hours post-aminophylline therapy.

CONCLUSIONS

Aminophylline increases urine output in critically ill children with AKI. A higher resolution version of the Graphical abstract is available as Supplementary information.

The diuretic effect of adding aminophylline or theophylline to furosemide in pediatric populations: a systematic review

The diuretic effect of the combined furosemide and aminophylline/theophylline among pediatric patients remains unclear. The primary aim of this systematic review was to examine the clinical diuretic effects (urine output and fluid balance) of co-administration of furosemide and aminophylline/theophylline as compared to furosemide alone in pediatric population. Ovid MEDLINE, CENTRAL, and EMBASE were searched from its inception until March 2022 for observational studies and randomized controlled trials (RCTs) comparing the administration of furosemide versus furosemide and aminophylline/theophylline in pediatric population. Case reports, case series, commentaries, letters to editors, systematic reviews, and meta-analyses were excluded. Five articles with a total sample population of 187 patients were included in this systematic review. As compared to the furosemide alone, our pooled data demonstrated that co-administration of furosemide and aminophylline/theophylline was associated with higher urine output (mean difference: 2.91 [90% CI 1.54 to 4.27], p < 0.0001, I² = 90%) and a more negative fluid balance (mean difference - 28.27 [95% CI: - 46.21 to - 10.33], p = 0.002, I² = 56%) than those who received furosemide alone.

CONCLUSION

This is the first paper summarizing the evidence of combined use of furosemide with aminophylline/theophylline in pediatric population. Our systematic review demonstrated that the co-administration of furosemide and aminophylline/theophylline could potentially yield better diuretic effects of urine output and negative fluid balance than furosemide alone in pediatric patients with fluid overload. Given the substantial degree of heterogeneity and low level of evidence, future adequately powered trials are warranted to provide evidence regarding the combined use of aminophylline/theophylline and furosemide as diuretic in the pediatric population.

WHAT IS KNOWN

• Fluid overload is associated with poor prognosis for children in the intensive care unit. • The ineffective result of furosemide alone, even at high dose, as diuretic agent for children with diuretic resistant fluid overload in the intensive care unit.

WHAT IS NEW

• This is the first systematic review that compares furosemide alone and co-administration of furosemide and aminophylline/theophylline. • This paper showed potential benefit of co-administration of furosemide and aminophylline/theophylline promoting urine output and negative fluid balance compared to furosemide alone.

The Effect of Aminophylline on Urine Output and Fluid Balance after a Single Dose in Children Admitted to the Pediatric Cardiac Intensive Care Unit

The purpose of this retrospective study was to investigate the effects of a single dose of aminophylline on urine output and fluid balance in children admitted to the cardiac intensive care unit. A retrospective study was performed to compare variables of interest before and 24 hours after aminophylline administration in children under the age of 18 years who were admitted to the cardiac intensive care unit at our institution from January 2011 onwards. Variables of interest included age, weight, aminophylline dose, concurrently administered diuretics, specific hemodynamic parameters, and blood urea nitrogen and creatinine levels. Variables such as urine output and fluid balance were measured through a binary endpoint. Data were compared in a paired fashion and continuous variables were compared through paired t-tests. Analyses were conducted using SPSS Version 23.0. A total of 14 patients were included in the study. There was no significant change in hemodynamic parameters or creatinine levels before and after intravenous aminophylline administration of 5 mg/kg. There was a significant difference in urine output, fluid balance, and blood urea nitrogen levels from the baseline value. Concurrent usage of diuretics did not show significant association with a difference in urine output or fluid balance from baseline. No significant adverse reactions were noted 24 hours after administration of aminophylline. Use of aminophylline dosed at 5 mg/kg is safe and leads to improvement in urine output and fluid balance without negatively impacting systemic oxygen delivery or renal filtration function.

Effect of Aminophylline in Preventing Renal Dysfunction among Neonates with Prenatal Asphyxia: A Clinical Trial

BACKGROUND

As there are different views on the effects of aminophylline on neonatal renal function, we intended to observe the effects of aminophylline on renal dysfunction in neonates with prenatal asphyxia.

METHODS

This randomized trial was conducted in the Obstetrics and Gynecology Hospital, Tehran, Iran, from June 2016 to May 2017, in neonates with moderate to severe asphyxia during birth. Fifty-six neonates were divided randomly into two groups. The intervention group received one dose of 5mg/kg slow intravenous aminophylline injection and the placebo group received 2 mL/kg of intravenous 10% solution of dextrose saline during the first hour of life. They were monitored and compared for renal functional indices, electrolytes, and complications of asphyxia during the three days of life.

RESULTS

The mean of Cr (37.9 ± 8.8 vs 38.5 ± 9.4 and 20.8 ± 4.8 vs 30.1 ± 5.2 μmol/L), GFR (21.55 ± 4.7 vs 20.25 ± 4.4 and 30.8 ± 7.1 vs 20.1 ± 6.5 mL/minute/1.73 m²), Na (135.1 ± 12.4 vs134.5 ± 11.2 and 128.9 ± 11.5 vs 134.2 ± 10.9 mEq/L), and urine output (98.2 ± 25 vs 96.8 ± 23 and 148.7 ± 35 vs 108.8 ± 20 cc) were in the aminophylline treated and placebo group on the 1st and 3rd days, respectively. The mean difference of Cr (-9.3 (-8.9; -9.7) μmol/L); (P = 0.02), GFR (10.7 (10.1; 11.3) mL/minute/1.73 m²) (P = 0.009), Na (-5.3 (-5.9; -4.7) mEq/L) (P = 0.002), and urine volume (39.9 (24.9; 54.9) cc) (P = 0.001) presented statistically significant differences on the third day between the intervention and placebo group.

CONCLUSION

Aminophylline was effective in preventing renal dysfunction in neonates with asphyxia. Neonates who received aminophylline indicated a significant improvement in GFR and urine output on the first day of life.

Xanthine Derivatives for Kidney Protection in the Critically Ill Pediatric Population: A Systematic Review

Different types of diuretics have been used to minimize fluid overload after resuscitation. This meta-analysis determined the effects of xanthine derivatives on creatinine, creatinine clearance, and urine output. Studies included data from pediatric patients, whoused theophylline or aminophylline, and included pre- and postxanthine data for at least one of the outcomes of interest. A total of 13 studies with 198 patients were included in the pooled analyses. The study recorded data prior, and a mean of 36 hours after xanthine administration. This meta-analysis demonstrates that xanthine derivatives in critically ill children, using a dose of approximately5 mg/kg, lead to a statistically significant increase in creatinine clearance and urine output without significantly altering serum creatinine. Xanthine derivatives may be beneficial for fluid management in critically ill children. Further studies are warranted assessing the association with additional clinical outcomes.

No Requirement for Targeted Theophylline Levels for Diuretic Effect of Aminophylline in Critically Ill Children

OBJECTIVES

To determine the relationship between theophylline trough levels and urine output in critically ill children administered aminophylline as adjunctive diuretic therapy.

DESIGN

Retrospective cohort study.

SETTING

The PICU of a tertiary care children's hospital.

PATIENTS

A mixed population of medical/surgical including postoperative cardiothoracic surgery patients less than 18 years old.

INTERVENTIONS

Electronic medical records of all PICU patients admitted from July 2010 to June 2015 were reviewed, and patients who received aminophylline as diuretic therapy were identified.

MEASUREMENTS AND MAIN RESULTS

Patient cohort data including demographics, daily aminophylline, furosemide and chlorothiazide dosing, theophylline trough levels, fluid intake, urine output and total fluid balance, blood urea nitrogen, and creatinine levels were abstracted. Multivariate analysis based on a generalized estimating equations approach demonstrated that aminophylline administration, when analyzed as a categorical variable, was associated with an increase in urine output and decreased fluid balance. However, aminophylline dosing, when analyzed as a continuous variable, was associated with neither an increase in urine output nor decreased fluid balance. Theophylline trough levels were not correlated with urine output at 24 hours (p = 0.78) and were negatively correlated with urine output at 48 hours (r = 0.078; p < 0.005).

CONCLUSIONS

Aminophylline administration provided a measure of increased diuresis, regardless of dosage, and theophylline trough levels. Therefore, achieving a prescribed therapeutic trough level may not be necessary for full diuretic effect. Because, as opposed to the diuretic effect, the side effect profile of aminophylline is dose-dependent, low maintenance dosing may optimize the balance between providing adjunctive diuretic effect while minimizing the risk of toxicity.

Management of Fluid Overload in the Pediatric ICU

The implications and management of fluid overload in pediatric critical care remain areas of ongoing controversy. Consensus definitions and methods of quantitating fluid overload continue to evolve, paralleling our growing understanding of fluid dynamics in critically ill patients. Fluid overload has been associated with adverse outcomes in some patient populations; guidelines for fluid management therapies are sparse and have little supporting data. Conflicting data for efficacy of therapies such as diuretic medications and renal replacement therapy are likely reflective of an incomplete understanding of the dynamic relationship between critical illness and fluid overload. Although some guidance regarding diuresis, continuous renal replacement therapy, and fluid balance goals is elucidated in the following chapters, it is important to recognize that further research into these management strategies is required before standardized approaches to management can be established.

A Double-Blinded, Randomized, Placebo-Controlled Clinical Trial of Aminophylline to Prevent Acute Kidney Injury in Children Following Congenital Heart Surgery With Cardiopulmonary Bypass

OBJECTIVES

Acute kidney injury occurs commonly in children following congenital cardiac surgery with cardiopulmonary bypass and has been associated with increased morbidity and mortality. Aminophylline, a methylxanthine nonselective adenosine receptor antagonist, has been effective in the management of acute kidney injury in certain populations. This study sought to determine whether postoperative administration of aminophylline attenuates acute kidney injury in children undergoing congenital cardiac surgery with cardiopulmonary bypass.

DESIGN

Single-center, double-blinded, placebo-controlled, randomized clinical trial.

SETTING

Tertiary center, pediatric cardiovascular ICU.

PATIENTS

A total of 144 children after congenital heart surgery with cardiopulmonary bypass.

INTERVENTIONS

Seventy-two patients were randomized to receive aminophylline and 72 patients received placebo. Study drug was administered every 6 hours for 72 hours.

MEASUREMENTS AND MAIN RESULTS

The primary outcome variable was the development of any acute kidney injury, defined by the serum creatinine criteria of the Kidney Diseases: Improving Global Outcomes. Secondary outcomes included the development of severe acute kidney injury, time between cardiovascular ICU admission and first successful extubation, percent fluid overload, total fluid balance, urine output, bioelectrical impedance, and serum neutrophil gelatinase-associated lipocalin. The unadjusted rate and severity of acute kidney injury were not different between groups; 43 of 72 (60%) of the treatment group and 36 of 72 (50%) of the placebo group developed acute kidney injury (p = 0.32). Stage 2/3 acute kidney injury occurred in 23 of 72 (32%) of the treatment group and 15 of 72 (21%) of the placebo group (p = 0.18). Secondary outcome measures also demonstrated no significant difference between treatment and placebo groups. Aminophylline administration was safe; no deaths occurred in either group, and rates of adverse events were similar (14% in the treatment group vs 18% in the placebo group; p = 0.30).

CONCLUSIONS

In this placebo-controlled randomized clinical trial, we found no effect of aminophylline to prevent acute kidney injury in children recovering from cardiac surgery performed with cardiopulmonary bypass. Future study of preoperative aminophylline administration to prevent acute kidney injury may be warranted.

Initial experience using aminophylline to improve renal dysfunction in the pediatric cardiovascular ICU

OBJECTIVE

To determine if aminophylline administration is associated with improved creatinine clearance and greater urine output in children with acute kidney injury in the cardiovascular ICU.

DESIGN

Single-center retrospective cohort study.

SETTING

Pediatric cardiovascular ICU, university-affiliated children's hospital.

PATIENTS

Children with congenital or acquired heart disease in the cardiovascular ICU who received aminophylline to treat oliguric acute kidney injury and fluid overload.

INTERVENTIONS

Patients received aminophylline after consultation with a pediatric nephrologist. Data were collected retrospectively over 7 days to assess if aminophylline was associated with improvement in creatinine clearance, urine output, and fluid overload.

MEASUREMENTS AND MAIN RESULTS

Thirty-one patients received 52 aminophylline courses. Over the 7-day study period, serum creatinine decreased from a mean of 1.13 ± 0.91 to 0.87 ± 0.83 mg/dL (-0.05 mg/dL/d, p < 0.001). A concomitant increase was seen in estimated glomerular filtration rate from a mean of 50.0 ± 30.0 to 70.6 ± 58.1 mL/min/1.73 m (+3.66 mL/min/1.73 m/d, p < 0.001). Average daily urine output increased by 0.22 mL/kg/hr (p < 0.001), and fluid overload decreased on average by 0.42% per day in the 7-day study period (p = 0.005). Although mean furosemide dose increased slightly (0.12 mg/kg/d, p = 0.01), hydrochlorothiazide dosing did not significantly change over the study period. There were no complications related to aminophylline administration.

CONCLUSIONS

Our study suggests that aminophylline therapy may be associated with significantly improved renal excretory function and may augment urine output in children who experience oliguric acute kidney injury in the cardiovascular ICU. Additionally, we did not identify any aminophylline-related side effects in this high-risk cardiac population. Future prospective studies are necessary to confirm the safety profile and to ensure that the beneficial effects are independent of other clinical interventions.

Additive diuretic response of concurrent aminophylline and furosemide in children: a case series and a brief literature review

Aminophylline exerts a renovascular effect, acting by adenosine receptor blockade or type IV phosphodiesterase inhibition. Clinically, these drugs have been used with furosemide to induce diuresis in adults and neonates. However, reports on use of aminophylline in diuretic-dependent children are limited to a few studies. We report a case series of four critically ill children unresponsive to furosemide continuous infusion who were subsequently given aminophylline as an adjunct diuretic in the treatment of fluid overload. No side effects were evident. Administration of aminophylline at low doses (3 mg/kg) successfully promoted increased urine output over the 6-h study period in all four children.

Mobilising Oedema in the Oedematous Critically Ill Patient with ARDS: Do We Seek Natriuresis Not Diuresis?

In the treatment of the acute respiratory distress syndrome in the intensive care unit, one of the aims is to achieve a negative fluid balance. Traditional use of sole-agent loop diuretics such as furosemide often results in the loss of free water, dehydration, hypernatraemia and metabolic alkalosis, with therapeutic failure once water is replaced. A more rational approach is to induce natriuresis with loss of sodium in the urine to reduce extracellular and interstitial fluid volume, not total body water. Polypharmacy with a loop diuretic combined with other weak diuretics to prevent tubules modifying glomerular filtrate, promotes natriuresis with large volume urinary losses and minimal electrolyte disturbance, and the excretion of urine with a composition comparable to plasma.

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.

Diurétiques et prématuré

Diuretics are frequently used in preterm infants in various situations such as patent ductus arteriosus, respiratory distress syndrome, bronchopulmonary dysplasia or neonatal renal insufficiency. However, the beneficial effects reported in the literature are usually transient, without any obvious effect on important parameters such as duration of oxygen dependency, ventilator dependency, length of hospital stay, long-term outcome, or mortality. Moreover, these drugs may induce water-electrolyte disorders especially when used for a long-term period. Thus, we recommend a systematic analysis of the beneficial/risk ratio before any use of these drugs.

Aminophylline: exploring cardiovascular benefits versus medical malcontent

Although aminophylline/theophylline has been relegated to third- and fourth-line status in the cardiopulmonary armamentarium, its use in specific pathophysiologic states, especially those of cardiac etiology, can be of significant benefit. The consulting clinician should maintain an awareness of its potential as adjunctive therapy in cases of atrioventricular block, cardiac arrest, heart failure, and bradyarrhythmias in particular. It should not yet be shelved as an archaic agent.

Aminophylline as an adjunct diuretic for neonates--a case series

Aminophylline is an adenosine receptor antagonist. Adult and paediatric studies have demonstrated a diuretic effect of aminophylline due to increased renal blood flow and the inhibition of solute reabsorption in various segments of the nephron. We report a case series of five infants with volume overload despite frusemide treatment. Aminophylline was successfully used as an adjunct diuretic with increased urine output and effective weight loss occurring in all five neonates following its introduction.

Relationship between Natriuretic Peptides and Residual Diuresis during Continuous Hemodiafiltration

BACKGROUND

The reasons for the decrease or increase of urine output following the start of continuous venovenous hemodiafiltration (CVVHDF) have not yet been explained sufficiently. The renoprotective properties of natriuretic peptides were described.

METHODS

The levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were measured in 23 mechanically ventilated patients before and during the first 48 h of CVVHDF. Samples were drawn both from the ports proximal and distal to the filter. The results were compared between the group where daily diuresis (Vu) remained low or decreased and the group where diuresis increased to the level of 1.5 ml x kg(-1) x h(-1) or higher after 48 h of treatment. Left ventricular dysfunction (LVD) was defined as LV ejection fraction below 40%. A control group consisted of 10 patients exposed to abdominal surgery.

RESULTS

The average AVdiff (%) of ANP and BNP on filter were insignificant. Patients with increasing diuresis (n = 12) had significantly lower levels of both ANP (p < 0.001) and BNP (p < 0.005) than the patients with decreasing diuresis (n = 11). Significant correlations were revealed for ANP and Vu (p < 0.01) and for BNP and Vu (p < 0.05). The levels of both peptides were grossly elevated in comparison to controls and were predictive of survival. The differences between cardiac and non-cardiac patients were significant both for ANP and for BNP.

CONCLUSIONS

The elimination of ANP and BNP by the CVVHDF is negligible. The levels of natriuretic peptides are inversely related to Vu and predict survival. ANP and BNP levels correlate with left ventricular function even during acute renal failure and CVVHDF.

Population pharmacokinetics of theophylline during paediatric extracorporeal membrane oxygenation

AIMS

To determine the population pharmacokinetics of theophylline during extracorporeal membrane oxygenation (ECMO) from routine monitoring data.

METHODS

Retrospective data were collected from 75 term neonates and children (age range 2 days to 17 years) receiving continuous infusions of aminophylline (mean rate 9.2 +/- 2.6 micro g kg-1 min-1) during ECMO. A total of 160 plasma concentrations (range 1-8 per patient), sampled at time intervals ranging from 10 h to 432 h, were included. Population PK analysis and model building were carried out using WinNonMix Professional (Version 2.0.1). Cross-validation was used to evaluate the validity and predictive accuracy of the model.

RESULTS

A one-compartment model with first order elimination combined with an additive error model was found to best describe the data. Of the covariables tested, bodyweight significantly influenced clearance and volume of distribution, whereas age was an important determinant of clearance, as adjudged by the differences in the -2 x log likelihood (P < 0.005) and the residual error value. The final model parameters were estimated as: clearance (l h-1) = 0.023 x bodyweight (kg) + 0.000057 x age (days) and volume of distribution (l) = 0.57 x bodyweight (kg). The interindividual variability in clearance and volume of distribution was 38% and 40%, respectively. The residual error corresponded to a standard deviation of 3.6 mg l-1. Cross-validation revealed a median (95% confidence interval) model bias of 9.4% (2.9, 16.5%) and precision of 29.5% (24.8, 36.0%).

CONCLUSIONS

The estimated clearance is significantly lower, and volume of distribution higher, than previously reported in non-ECMO patients of similar age. These differences are probably a result of the expanded circulating volume during ECMO and altered renal and hepatic physiology in this critically ill group. Large interindividual variability reflects the heterogeneous nature of patients treated on ECMO.

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.