Inhaled and intravenous treatment in acute severe and life-threatening asthma

Pulmonary drug delivery and retention: A computational study to identify plausible parameters based on a coupled airway-mucus flow model

Pulmonary drug delivery systems rely on inhalation of drug-laden aerosols produced from aerosol generators such as inhalers, nebulizers etc. On deposition, the drug molecules diffuse in the mucus layer and are also subjected to mucociliary advection which transports the drugs away from the initial deposition site. The availability of the drug at a particular region of the lung is, thus, determined by a balance between these two phenomena. A mathematical analysis of drug deposition and retention in the lungs is developed through a coupled mathematical model of aerosol transport in air as well as drug molecule transport in the mucus layer. The mathematical model is solved computationally to identify suitable conditions for the transport of drug-laden aerosols to the deep lungs. This study identifies the conditions conducive for delivering drugs to the deep lungs which is crucial for achieving systemic drug delivery. The effect of different parameters on drug retention is also characterized for various regions of the lungs, which is important in determining the availability of the inhaled drugs at a target location. Our analysis confirms that drug delivery efficacy remains highest for aerosols in the size range of 1-5 μm. Moreover, it is observed that amount of drugs deposited in the deep lung increases by a factor of 2 when the breathing time period is doubled, with respect to normal breathing, suggesting breath control as a means to increase the efficacy of drug delivery to the deep lung. A higher efficacy also reduces the drug load required to be inhaled to produce the same health effects and hence, can help in minimizing the side effects of a drug.

Pulmonary drug delivery systems utilize the respiratory mechanism to directly deliver drugs to a target region of the lungs. The drug molecules deposit in the mucus lining, on reaching the target region, and are simultaneously transported away from the target region due to mucociliary transport and molecular diffusion. The availability of drugs at a target lung region and hence, efficacy of the drugs, therefore, determined by the delivery and retention of the drugs at the target region. The present study computationally solves the coupled transport equations to identify the conditions conducive for drug delivery and retention in the deep lungs. Drug delivery efficacy to the deep lung is observed to be highest for 1–5 μm aerosols. Breathing time period is also observed to influence efficacy. The amount of drugs deposited in the deep lung is observed to increase by a factor of 2 when the breathing time period is doubled with respect to normal breathing period. Such insights gained from this analysis will potentially help in devising mechanisms for increasing drug availability in the deep lung which is essential in achieving systemic drug delivery.

Oral enoximone allows the reduction and discontinuation of inhaled steroids and beta2 agonists in asthmatic children

In the last two decades, improvement on asthma treatment has been merely marginal for both adults and children; inhaled corticosteroids (ICS) combined with β-2-mimetics remain the main therapy [3,4]. "New" therapies are just variations on ICS or, for children, on various other drugs that were allowed for adult asthma patients (clinicaltrials.gov). Although currently monoclonal antibodies have been introduced to the field, there is still a large therapeutic burden, given the mortality rate and widespread prevalence of uncontrolled asthma [2]. A simple and adequate way to reduce distress and costs would have great merit. PDE3 inhibitor enoximone was used earlier in successful treatment of life-threatening bronchial asthma (status asthmaticus) as well as in preoperative settings to prevent patients with severe asthma from suffering major surgery-related exacerbations; also, translational mice models showed the anti-inflammatory effects when PDE3 was targeted. Both outcomes suggested a beneficial effect of enoximone in severe chronic asthma. We hypothesized that enoximone might also be helpful in patients with severe chronic asthma; hence, we treated (and followed) > 70 patients (age 0-77, all volunteers) with personalized low doses of enoximone (orally), among them 11 minors, who are described here. Both children and adults reported improvement and/or alleviation of their asthma symptoms. All patients reported a better quality of life and greater drug compliance. The drug was well tolerated and showed no/negligible side effects. Notable bonus: asthma-related comorbidities (allergies, eczema, and rhinitis) were reported also to be less severe or even to disappear. The evaluation shows that PDE3 inhibitor enoximone is an adequate alternative for or addition to current asthma therapeutics, as add-on as well as stand-alone, considerably reducing the use of β-2-mimetics/ICS, with no or negligible side effects. Additional studies are advisable.

The Utility of Various Pre-anesthetic Medications Based on Type of General Anesthesia

Background:

Premedication is used prior to surgery to reduce the adverse effects that might result from general anesthesia.

Objective:

This study was performed to examine the types and utility of various pre-anesthetic agents in 100 patients aged between 3 and 60 years who were admitted to Baladrooz General Hospital for different surgical operations during February (winter) and April (spring) 2021.

Methods:

A total of 62 patients received isoflurane, and 7 patients received sevoflurane, both by inhalational administration. The other 31 subjects were administered Marcaine (bupivacaine) by spinal anesthesia.

Results:

In this study, eight types of pre-anesthetic medication were administered prior to anesthesia, as follows: hydrocortisone (35 patients), metoclopramide (25 patients), atropine (13 patients), dexamethasone (12 patients), midazolam (7 patients), morphine (3 patients), ephedrine (3 patients), and fentanyl (2 patients). The most commonly used pre-anesthetic agent administered with isoflurane was hydrocortisone (37 patients), while the least used were fentanyl and morphine, which were administered to 3 patients each. Hydrocortisone was the premedication most often used (6 patients) with isoflurane, followed by dexamethasone, midazolam, and metoclopramide (5, 2, and 2 patients, respectively). The preanesthetic agent used most often with sevoflurane was hydrocortisone (6 patients), followed by dexamethasone (5 patients) and metoclopramide and midazolam (2 patients each). The premedication most commonly used with bupivacaine was metoclopramide (25 patients), while the least used was midazolam (2 patients).

Conclusion:

The study showed that several different pre-anesthetic drugs were used prior to anesthetic agents, which suggests that the selection of a pre-anesthetic drug depends on the risks that might be incurred when using a specific anesthetic drug.

Magnesium sulphate intravenously reduces tachycardia side-effects of β2-agonists

The review by Erumbalaet al. [1] correctly proposing magnesium sulphate (MgSO₄) as the first intravenous bronchodilator missed vital points of its pharmacological actions. The i.v. drug reduces or eliminates tachycardia and palpitation side-effects of β₂-agonists [2–5]. As well as relaxing smooth muscle of the bronchi, vasculature, gut and uterus, MgSO₄ slows cardiac atrial conduction [6, 7], and was used in the past to revert supraventricular tachycardia and fast atrial fibrillation [8, 9]. There is no evidence to be found for the 20–30 min infusion rate for i.v. MgSO₄ of 40–75 mg.kg⁻¹, and this infusion time will not create a sufficiently high serum level to relax bronchial smooth muscle. In acute-severe and life-threatening asthma i.v. MgSO₄ followed by i.v. β₂-agonist is safe [10]; an infusion time of 5 min for MgSO₄ has evidence for the safety of this speed of injection in obstetric [11] and cardiac literature, albeit in adults.

Intravenous magnesium sulphate allows safer intravenous β₂-agonist delivery in acute-severe and life-threatening asthma attackshttps://bit.ly/3veUpfC

Epinephrine (adrenaline) compared to selective beta-2-agonist in adults or children with acute asthma: a systematic review and meta-analysis

BACKGROUND

International asthma guidelines recommend against epinephrine (adrenaline) administration in acute asthma unless associated with anaphylaxis or angio-oedema. However, administration of intramuscular epinephrine in addition to nebulised selective β₂-agonist is recommended for acute severe or life-threatening asthma in many prehospital guidelines. We conducted a systematic review to determine the efficacy of epinephrine in comparison to selective β₂-agonist in acute asthma.

METHODS

We included peer-reviewed publications of randomised controlled trials (RCTs) that enrolled children or adults in any healthcare setting and compared epinephrine by any route to selective β₂-agonist by any route for an acute asthma exacerbation. The primary outcome was treatment failure, including hospitalisation, need for intubation or death.

RESULTS

Thirty-eight of 1140 studies were included. Overall quality of evidence was low. Seventeen studies contributed data on 1299 participants to the meta-analysis. There was significant statistical heterogeneity, I²=56%. The pooled Peto's OR for treatment failure with epinephrine versus selective β₂-agonist was 0.99 (0.75 to 1.32), p=0.95. There was strong evidence that recruitment age group was associated with different estimates of the odds of treatment failure; with studies recruiting adults-only having lower odds of treatment failure with epinephrine. It was not possible to determine whether epinephrine in addition to selective β₂-agonist improved outcomes.

CONCLUSION

The low-quality evidence available suggests that epinephrine and selective β₂-agonists have similar efficacy in acute asthma. There is a need for high-quality double-blind RCTs to determine whether addition of intramuscular epinephrine to inhaled or nebulised selective β₂-agonist improves outcome.

PROSPERO REGISTRATION NUMBER

CRD42017079472.

Biomaterials-Based Opportunities to Engineer the Pulmonary Host Immune Response in COVID-19

The COVID-19 pandemic caused by the global spread of the SARS-CoV-2 virus has led to a staggering number of deaths worldwide and significantly increased burden on healthcare as nations scramble to find mitigation strategies. While significant progress has been made in COVID-19 diagnostics and therapeutics, effective prevention and treatment options remain scarce. Because of the potential for the SARS-CoV-2 infections to cause systemic inflammation and multiple organ failure, it is imperative for the scientific community to evaluate therapeutic options aimed at modulating the causative host immune responses to prevent subsequent systemic complications. Harnessing decades of expertise in the use of natural and synthetic materials for biomedical applications, the biomaterials community has the potential to play an especially instrumental role in developing new strategies or repurposing existing tools to prevent or treat complications resulting from the COVID-19 pathology. Leveraging microparticle- and nanoparticle-based technology, especially in pulmonary delivery, biomaterials have demonstrated the ability to effectively modulate inflammation and may be well-suited for resolving SARS-CoV-2-induced effects. Here, we provide an overview of the SARS-CoV-2 virus infection and highlight current understanding of the host's pulmonary immune response and its contributions to disease severity and systemic inflammation. Comparing to frontline COVID-19 therapeutic options, we highlight the most significant untapped opportunities in immune engineering of the host response using biomaterials and particle technology, which have the potential to improve outcomes for COVID-19 patients, and identify areas needed for future investigations. We hope that this work will prompt preclinical and clinical investigations of promising biomaterials-based treatments to introduce new options for COVID-19 patients.

Intravenous and intramuscular therapy in near fatal asthma. A response to Al-Shamrani

The invited review by Al-Shamrani et al. (2020) [1] failed to address the management of a patient having an asthma attack who arrives in the Emergency Department with respiratory failure or in a moribund condition. The only route available for drug therapy in these patients is intravenously (IV) or intramuscularly in a final attempt to reduce bronchoconstriction. This could avoid tracheal intubation and lung ventilation, or make these procedures safer (Sellers, 2013; Williams et al., 1992) [2,3] for the patient if some bronchodilation occurs. Intubation and ventilation prevent coughing but tenacious mucus remains which blocks the bronchi. There are no randomised controlled trials or national asthma guidelines to inform practice at this stage of the disease, especially in under 18 year olds, so case report evidence, experience, common sense, and pharmacological principles must be engaged to save the patient’s life.

Evaluation and management of the critically ill adult asthmatic in the emergency department setting

INTRODUCTION

Asthma is a common reason for presentation to the Emergency Department and is associated with significant morbidity and mortality. While patients may have a relatively benign course, there is a subset of patients who present in a critical state and require emergent management.

OBJECTIVE

This narrative review provides evidence-based recommendations for the assessment and management of patients with severe asthma.

DISCUSSION

It is important to consider a broad differential diagnosis for the cause and potential mimics of asthma exacerbation. Once the diagnosis is determined, the majority of the assessment is based upon the clinical examination. First line therapies for severe exacerbations include inhaled short-acting beta agonists, inhaled anticholinergics, intravenous steroids, and magnesium. Additional therapies for refractory cases include parenteral epinephrine or terbutaline, helium‑oxygen mixture, and consideration of ketamine. Intravenous fluids should be administered, as many of these patients are dehydrated and at risk for hypotension if they receive positive pressure ventilatory support. Noninvasive positive pressure ventilation may prevent the need for endotracheal intubation. If mechanical ventilation is required, it is important to avoid breath stacking by setting a low respiratory rate and allowing permissive hypercapnia. Patients with severe asthma exacerbations will require intensive care unit admission.

CONCLUSIONS

This review provides evidence-based recommendations for the assessment and management of severe asthma with a focus on the emergency clinician.

An Efficient, Lung-Targeted, Drug-Delivery System To Treat Asthma Via Microparticles

BACKGROUND

Chronic diseases such as diabetes, asthma, and heart disease are the leading causes of death in developing countries. Public health plays an important role in preventing such diseases to improve individuals' quality of life. Conventional dosage schemes used in public health to cure various diseases generally lead to undesirable side effects and renders the overall treatment ineffective. For example, a required concentration of drug cannot reach the lungs using conventional methods to cure asthma. Microspheres have emerged as a confirmed drug-delivery system to cure asthma.

METHOD

In this paper, a salbutamol-loaded poly lactic acid-co-glycolic acid-polyethylene glycol (PLGA-PEG) microsphere (SPP)-based formulation was prepared using a Buchi B-90 nanospray drier. Face-centered central composite design (CCD) was applied to optimize the spray-drying process.

RESULTS

The drug content and product yield were found to be 72%±0.8% and 86%±0.4%, respectively; drug release (91.1%) peaked for up to 12 hrs in vitro. Microspheres obtained from the spray dryer were found to be shriveled. The experiments were carried out and verified using various groups of rabbits. In our study, the particle size (8.24 µm) was observed to be an essential parameter for drug delivery. The in vivo results indicated that the targeting efficacy and drug concentration in the lung was higher with the salbutamol-loaded PLGA-PEG SPP formulation (1,410.1±10.11 µg/g, 15 mins), as compared to the conventional formulation (92±0.56 µg/g, 10 min). The final product was stable under 5°C±2°C, 25°C±2°C, and 40°C±2°C/75%±5% relative humidity. In addition, these co-polymers have a good safety profile, as determined by testing on human alveolar basal epithelium A549 cell lines.

CONCLUSION

Our results prove that microspheres are an alternative drug-delivery system for lung-targeted asthma treatments used in public health.

Outcomes of paediatric critical care asthma patients

AIM

The aim of this study was to characterise patients with asthma admitted to an Australian paediatric intensive care unit (PICU).

METHODS

This was a retrospective review of patients with asthma admitted to a university-affiliated, 23-bed, tertiary PICU between January 2000 and December 2011, with a subset of pharmacotherapy and biochemical data from patients admitted between July 2007 and December 2011.

RESULTS

A total of 589 admissions (501 patients) with asthma over 12 years constituted 4.4% of all PICU admissions. Three patients died (0.6%). Non-invasive ventilation (NIV) was used in 104 (17.7%) admissions, and 41 (7%) were invasively ventilated. On 12 (2%) occasions, patients received both NIV and invasive ventilation. Over 12 years, there was a significant trend to increased use of NIV, 11-39% (P < 0.0001), and invasive ventilation, 6-14% (P < 0.001). All received steroids and nebulised β2-agonists. A total of 92% received intravenous (IV) β2-agonists, 65% of these for less than 12 h. PICU and hospital stay were proportional to the duration of IV β2-agonist infusion (P < 0.0001). A total of 47.1% received IV magnesium sulphate, increasing from 19 to 75% (P < 0.001). The majority (48%) were transferred directly to PICU from other hospitals. Median PICU stay was 1.04 days (0.72-1.63); hospital stay was 3.16 days (2.29-4.71), and both were unchanged.

CONCLUSIONS

Intensive care length of stay (LOS) was unchanged over 12 years. Both invasive and NIV and IV magnesium sulphate use increased. LOS was directly related to the duration of IV β2-agonist. Asthma patients admitted to PICU typically have a brief stay and have a fairly predictable course. Prospective studies could explore the contribution of IV agents and the role of NIV.

Asthma pressurised metered dose inhaler performance: propellant effect studies in delivery systems

BACKGROUND

Current pressurised metered dose asthma inhaler (pMDI) propellants are not inert pharmacologically as were previous chlorofluorocarbons, have smooth muscle relaxant' partial pressure effects in the lungs and inhaled hydrofluoroalkane 134a (norflurane) has anaesthetic effects. Volumes of propellant gas per actuation have never been measured.

METHODS

In-vitro studies measured gas volumes produced by pMDIs on air oxygen (O2) levels in valved holding chambers (VHC) and the falls in O2% following actuation into lung ventilator delivery devices.

RESULTS

Volumes of propellant gas hydrofluoroalkane (HFA) 134a and 227ea and redundant chlorofluorocarbons (CFC) varied from 7 ml per actuation from a small salbutamol HFA inhaler to 16 ml from the larger. Similar-sized CFC pMDI volumes were 15.6 and 20.4 ml. Each HFA salbutamol inhaler has 220 full volume discharges; total volume of gas from a small 134a pMDI was 1640 ml, and large 3885 ml. Sensing the presence of liquid propellant by shaking was felt at the 220th discharge in both large and small inhalers. Because of a partial pressure effect, VHC O2% in air was reduced to 11% in the smallest 127 ml volume VHC following 10 actuations of a large 134a salbutamol inhaler. The four ventilator delivery devices studied lowered 100% oxygen levels to a range of 93 to 81% after five actuations, depending on the device and type of pMDI used.

CONCLUSION

Pressurised inhaler propellants require further study to assess smooth muscle relaxing properties.

Management of Acute Exacerbation of Asthma and Chronic Obstructive Pulmonary Disease in the Emergency Department

Acute asthma and chronic obstructive pulmonary disease (COPD) exacerbations are the most common respiratory diseases requiring emergent medical evaluation and treatment. Asthma and COPD are chronic, debilitating disease processes that have been differentiated traditionally by the presence or absence of reversible airflow obstruction. Asthma and COPD exacerbations impose an enormous economic burden on the US health care budget. In daily clinical practice, it is difficult to differentiate these 2 obstructive processes based on their symptoms, and on their nearly identical acute treatment strategies; major differences are important when discussing anatomic sites involved, long-term prognosis, and the nature of inflammatory markers.

Insulin therapy in hyperglycemic children with severe acute asthma

OBJECTIVES

The aim of this study was to assess the effect of intravenous (IV) insulin administration in children with severe acute asthma (SAA) and hyperglycemia on IV salbutamol consumption and length of stay (LOS) in a pediatric intensive care unit (PICU).

METHODS

Retrospective, descriptive study of the clinical course before and after implementation of an insulin protocol for the treatment of hyperglycemia (i.e. blood glucose >8 mmol/L or 144 mg/dL, respectively) in the PICU of a tertiary care university hospital. Admissions between 1994 and 2010 were reviewed. The insulin protocol was introduced in 2006.

RESULTS

A total of 131 pediatric patients with SAA complicated by hyperglycemia requiring IV salbutamol were included. Severity of illness before and after implementation of the insulin protocol did not significantly differ. The insulin-treated patient group had significantly higher maximum blood glucose levels and higher cumulative IV salbutamol dose than the non-treated group. There were no differences between these groups in the duration of IV salbutamol administration and LOS.

CONCLUSIONS

In view of the lack of difference in outcomes and considering that the insulin protocol is labor-intensive, the question is whether this protocol is efficacious for the treatment of pediatric SAA associated with hyperglycemia.

Critical Asthma Syndrome in the ICU

Critical asthma syndrome represents the most severe subset of asthma exacerbations, and the critical asthma syndrome is an umbrella term for life-threatening asthma, status asthmaticus, and near-fatal asthma. According to the 2007 National Asthma Education and Prevention Program guidelines, a life-threatening asthma exacerbation is marked by an inability to speak, a reduced peak expiratory flow rate of <25 % of a patient's personal best, and a failed response to frequent bronchodilator administration and intravenous steroids. Almost all critical asthma syndrome cases require emergency care, and most cases require hospitalization, often in an intensive care unit. Among asthmatics, those with the critical asthma syndrome are difficult to manage and there is little room for error. Patients with the critical asthma syndrome are prone to complications, they utilize immense resources, and they incite anxiety in many care providers. Managing this syndrome is anything but routine, and it requires attention, alacrity, and accuracy. The specific management strategies of adults with the critical asthma syndrome in the hospital with a focus on intensive care are discussed. Topics include the initial assessment for critical illness, initial ventilation management, hemodynamic issues, novel diagnostic tools and interventions, and common pitfalls. We highlight the use of critical care ultrasound, and we provide practical guidelines on how to manage deteriorating patients such as those with pneumothoraces. When standard asthma management fails, we provide experience-driven recommendations coupled with available evidence to guide the care team through advanced treatment. Though we do not discuss medications in detail, we highlight recent advances.