Heliox for Pediatric Critical Asthma: A Multicenter, Retrospective, Registry-Based Descriptive Study

Invasive Respiratory Support in Critical Pediatric Asthma

In the United States and Canada, severe asthma requiring mechanical ventilation has declined over the past decade reflecting a rise in noninvasive therapies. When aggressive noninvasive therapies fail, endotracheal intubation and mechanical ventilation are lifesaving and should be planned for in advance. As speed is important, the most experienced practitioner should intubate and rapid correction of hypercarbia and respiratory acidosis should be avoided. An elevated minute ventilation may cause pulmonary hyperinflation leading to air-leak syndrome and/or hemodynamic instability. Patients with severe air flow obstruction in asthma typically have near-normal respiratory system compliance. Therefore, an increase in plateau pressure (Pplat) usually reflects dynamic hyperinflation. A suggested upper limit for Pplat is 25-30 cm H2O. Intrinsic PEEP (PEEPi) is measured with an expiratory hold and is valuable in that PEEP set on the ventilator can be lower than PEEPi. A reasonable ventilation strategy involving low ventilator rates and PEEP without quick correction of blood gases should be adopted. Alternative modalities to conventional mechanical ventilation are limited and unless very experienced with high-frequency oscillatory ventilation, the risk likely outweighs benefit. Heliox may be beneficial but cannot be delivered by every ventilator and this varies by manufacturer. Inhaled anesthetics are direct bronchodilators and likely beneficial but as no conventional ICU ventilator can deliver them, close cooperation with Anesthesiology is needed. Extracorporeal membrane oxygenation (ECMO) is a rescue therapy that is particularly useful in cases of severe air-leak syndrome. As with mechanical ventilation, ECMO does not reverse the asthma disease process but allows support of the patient until there is improvement with other therapies. Most children who die experience cardiac arrest prior to hospitalization. Otherwise, most mechanically ventilated children survive to hospital discharge but there is a suggestion of additional mortality from asthma in the following decade.

Noninvasive Respiratory Support for Pediatric Critical Asthma

Pediatric asthma is a common cause of emergency department visits and hospital admissions. Whereas most patients respond well to standard pharmacologic treatments, those with more severe disease frequently require noninvasive respiratory support (NRS) and adjunct therapies or admission to an ICU-a condition termed critical asthma. NRS modalities include high-flow nasal cannula, CPAP, and noninvasive ventilation to deliver standard air-oxygen mixtures or helium-oxygen (heliox). Each NRS modality offers distinct physiological benefits, primarily aimed at reducing work of breathing, enhancing gas exchange, and optimizing aerosol delivery. Despite the growing use of NRS, robust evidence supporting its efficacy in pediatric critical asthma is limited, with few published clinical trials and a heavy reliance on observational studies to inform clinical practice. This narrative review explores the current evidence, physiological rationale, practical considerations, and future research directions for the use of NRS in pediatric critical asthma. The goal is to provide clinicians with a comprehensive overview of the benefits and limitations of NRS modalities to better inform therapeutic decisions and improve patient outcomes.

Heliox ventilation in elderly, hypertensive ICU patients improves microcirculation: A randomized controlled study

BACKGROUND

Conventional mechanical ventilation has adverse impacts on the hemodynamics of elderly, hypertensive ICU patients. Limited studies have addressed ways to ameliorate these negative effects. This study aimed to determine whether heliox ventilation could improve the hemodynamics, especially microcirculation, of elderly, hypertensive patients undergoing mechanical ventilation.

METHODS

Thirty-eight patients, over the age of 65 with essential hypertension who underwent invasive mechanical ventilation treatment, were divided into two groups: a control group of nitrogen‑oxygen ventilation (n = 19) and an experimental group of heliox ventilation (n = 19). The control group received conventional room air ventilation and the experimental group adopted the innovative, closed heliox ventilation technique. Changes in blood pressure, heart rate (HR), peripheral oxygen saturation (SpO2), central venous oxygen saturation (ScvO2), regional cerebral oxygen saturation (rSO2), lactic acid (Lac) and airway pressure were measured at 0,1,2,3 h under volume-controlled ventilation (VCV) mode throughout the study. Sublingual microcirculation parameters were additionally measured at 0 h and 3 h of ventilation treatment.

RESULTS

SpO2 in both groups increased after 1 h of ventilation compared with 0 h (p < 0.001), subsequently remaining stable. Compared with the control group, the experimental group showed a decrease in airway pressure and Lac, while blood pressure, ScvO2, and rSO2 increased (p < 0.05). Moreover, the sublingual microcirculation indexes in the experimental group improved compared with the control group (p < 0.05).

CONCLUSIONS

Heliox ventilation improves blood pressure and microcirculation in elderly hypertensive patients and may resolve the limitations of traditional nitrogen‑oxygen ventilation.

TRIAL REGISTRATION

This trial was registered. The Chinese trial registration number is ChiCTR2100043945. The date of registration is 6-3-2021.

Status Asthmaticus in the Pediatric ICU: A Comprehensive Review of Management and Challenges

This narrative review addresses the significant burden of pediatric status asthmaticus, which comprises almost 20% of admissions to pediatric intensive care units (PICUs). It highlights the diverse modalities employed in the PICU for managing this life-threatening condition, and thoroughly discusses the literature in support of or against these treatment modalities.

Wide Institutional Variability in the Treatment of Pediatric Critical Asthma: A Multicenter Retrospective Study

OBJECTIVES

Children with status asthmaticus refractory to first-line therapies of systemic corticosteroids and inhaled beta-agonists often receive additional treatments. Because there are no national guidelines on the use of asthma therapies in the PICU, we sought to evaluate institutional variability in the use of adjunctive asthma treatments and associations with length of stay (LOS) and PICU use.

DESIGN

Multicenter retrospective cohort study.

SETTING

Administrative data from the Pediatric Health Information Systems (PHIS) database.

PATIENTS

All inpatients 2-18 years old were admitted to a PHIS hospital between 2013 and 2021 with a diagnostic code for asthma.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

This study included 213,506 inpatient encounters for asthma, of which 29,026 patient encounters included care in a PICU from 39 institutions. Among these PICU encounters, large variability was seen across institutions in both the number of adjunctive asthma therapies used per encounter (min: 0.6, median: 1.7, max: 2.5, p < 0.01) and types of adjunctive asthma therapies (aminophylline, ipratropium, magnesium, epinephrine, and terbutaline) used. The center-level median hospital LOS ranged from 1 (interquartile range [IQR]: 1, 3) to 4 (3, 6) days. Among all the 213,506 inpatient encounters for asthma, the range of asthma admissions that resulted in PICU admission varied between centers from 5.2% to 47.3%. The average number of adjunctive therapies used per institution was not significantly associated with hospital LOS ( p = 0.81) nor the percentage of encounters with PICU admission ( p = 0.47).

CONCLUSIONS

Use of adjunctive therapies for status asthmaticus varies widely among large children's hospitals and was not associated with hospital LOS or the percentage of encounters with PICU admission. Wide variance presents an opportunity for standardizing care with evidence-based guidelines to optimize outcomes and decrease adverse treatment effects and hospital costs.

Efficacy and Safety of Prolonged Magnesium Sulfate Infusions in Children With Refractory Status Asthmaticus

OBJECTIVES

There is a paucity of data on the use of intravenous magnesium sulfate infusion in children with refractory status asthmaticus. The purpose of this study was to evaluate the efficacy and safety of prolonged magnesium sulfate infusion as an advanced therapy.

METHODS

This is a single center retrospective study of children admitted to our pediatric intensive care unit (PICU) with status asthmaticus requiring continuous albuterol. Treatment group included patients receiving magnesium for ≥4 h and control group included those on other therapies only. Patients were matched 1:4 based on age, sex, obesity, pediatric index of mortality III and pediatric risk of mortality III scores. Primary outcomes included PICU length of stay (LOS) and mechanical ventilation (MV) requirement. Secondary outcomes included mortality, extracorporeal membrane oxygenation (ECMO) requirement, analyses of factors associated with PICU LOS and MV requirement and safety of magnesium infusion. Logistic and linear regressions were employed to determine factors associated with MV requirement and PICU LOS, respectively.

RESULTS

Treatment and control groups included 27 and 108 patients, respectively. Median initial infusion rate was 15 mg/kg/hour, with median duration of 28 h. There was no difference in the MV requirement between the treatment and control groups [7 (25.9%) vs. 20 patients (18.5%), p = 0.39]. Median PICU LOS and ECMO use were significantly higher in treatment vs. control group [(3.63 vs. 1.09 days, p < 0.01) and (11.1 vs. 0%, p < 0.01), respectively]. No mortality difference was noted. On regression analysis, patients receiving ketamine and higher prednisone equivalent dosing had higher odds of MV requirement [OR 19.29 (95% CI 5.40-68.88), p < 0.01 and 1.099 (95% CI 1.03-1.17), p < 0.01, respectively]. Each mg/kg increase in prednisone equivalent dosing corresponded to an increase in PICU LOS by 0.13 days (95% CI 0.096-0.160, p < 0.01). Magnesium infusions were not associated with lower MV requirement or lower PICU LOS after controlling for covariates. Fourteen (51.9%) patients in the treatment group had an adverse event, hypotension being the most common.

CONCLUSION

Magnesium sulfate infusions were not associated with MV requirement, PICU LOS or mortality.