Nebulized Ketamine Plus Standard Care vs. Standard Care Alone in Moderate to Severe Asthma Exacerbations

• Nebulized ketamine (0.5 mg/kg in normal saline to a total volume of 5ml) plus standard asthma excaerbationcare (Drug): **Intervention Description:** Nebulized ketamine is administered as a single dose of 0.5 mg/kg of ketamine hydrochloride diluted in 0.9% normal saline to a total volume of 5ml. The solution is delivered via a standard jet nebulizer over approximately 15-20minutes. This intervention is given once at the time of enrollment in the emergency department, in addition to standard asthma care. The ketamine used is in injectable solution form (typically 50 mg/mL concentration), drawn and diluted immediately prior to nebulization. Participants are monitored continuously for 60 minutes after administration to assess changes in peak expiratory flow rate (PEFR), symptom relief, and adverse events. The goal is to evaluate the bronchodilatory effect and safety of nebulized ketamine in adults with moderate to severe asthma exacerbation who present to the emergency department.
• Placebo nebulization (5 mL normal saline) plus standard asthma care (Drug): **Intervention Description (Control Group):** Participants in the control group will receive a single nebulized dose of 5 mL of 0.9% normal saline, delivered using a standard jet nebulizer over approximately 10-15 minutes. This placebo intervention is administered once at the time of enrollment in the emergency department, after standard asthma care. Standard care includes repeated doses of nebulized salbutamol and ipratropium, systemic corticosteroids (oral or intravenous), and supplemental oxygen as needed. The placebo solution is identical in appearance and volume to the active ketamine solution used in the intervention group to maintain blinding. All participants will be monitored for 60 minutes after nebulization to assess changes in peak expiratory flow rate (PEFR), symptom relief using a visual analog scale (VAS), and the occurrence of any adverse events.

Primary outcomes

• Change in Peak Expiratory Flow Rate (PEFR) from baseline to 60 minutes post-intervention [Baseline (0 minutes) and 60 minutes post-intervention]: PEFR will be measured using a peak flow meter at baseline (0 minutes) and at 60 minutes after administration of the intervention. The change in PEFR will be calculated to assess the intervention effect.

Secondary outcomes

• Change in PEFR at 30 minutes [30 minutes]
• • Incidence of adverse effects [60 minutes]
• Incidence of intravenous magnesium sulfate administration [60 minutes]: The proportion of participants who receive intravenous magnesium sulfate as part of escalation of care after 60 minutes post-intervention.
• Incidence of ICU admission [60 minutes]: The proportion of participants who require transfer to an intensive care unit (ICU) after 60 minutes post-intervention.
• Incidence of endotracheal intubation [60 minutes]: The proportion of participants who undergo endotracheal intubation after 60 minutes post-intervention due to clinical deterioration.
• Incidence of non-invasive ventilation (BiPAP) initiation [60 minutes]: The proportion of participants who require initiation of bilevel positive airway pressure (BiPAP) after 60 minutes post-intervention as part of escalation of care.
• Disposition plan (discharged, admitted, or transferred) [60 minutes]
• Length of stay (if admitted) [60 minutes]
• Type of admission bed (e.g., ward vs. ICU) [60 minutes]
• Change in dyspnea severity as measured by the Visual Analogue Scale (VAS) [60 minutes]: Patient-reported breathlessness will be assessed using the Visual Analogue Scale (VAS), a 10-centimeter horizontal line ranging from 0 to 10. A score of 0 represents "no breathlessness," and a score of 10 represents "worst imaginable breathlessness." The change in VAS score from baseline to 60 minutes post-intervention will be recorded.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

1. Adults aged 18 years or older presenting to the Emergency Department with a clinical diagnosis of moderate to severe asthma exacerbation based on SIGN (Scottish Intercollegiate Guidelines Network) criteria.
2. PEFR between 33% and 75% of predicted value or personal best, as measured using a peak flow meter.
3. Stable vital signs as deemed by the treating physician
4. Alert and oriented, able to understand the study purpose and provide informed consent.
5. Not requiring immediate advanced airway intervention, including intubation or emergency non-invasive ventilation.

Exclusion Criteria:

1. Known hypersensitivity or allergy to ketamine or any component of the nebulized solution.
2. History of psychosis, schizophrenia, or other severe uncontrolled psychiatric disorders.
3. Uncontrolled hypertension, defined as systolic BP > 180 mmHg or diastolic BP > 110 mmHg on two consecutive readings at least 5 minutes apart, despite initial ED management.
4. Hemodynamic instability, including persistent hypotension (SBP < 90 mmHg) or tachyarrhythmias requiring urgent treatment.
5. Significant chronic lung disease, including:

   * COPD with frequent exacerbations or baseline FEV₁ < 50% predicted
   * Interstitial lung disease (ILD)
   * Clinically significant bronchiectasis with baseline productive cough or infection
6. Pregnancy or currently breastfeeding.
7. Home BiPAP use or requirement for non-invasive ventilation (e.g., BiPAP/CPAP) during the ED visit (Note: isolated home CPAP for sleep apnea without daytime symptoms is acceptable).
8. Current intubation or imminent need for mechanical ventilation based on clinical judgment.
9. Severe cardiac disease, including decompensated heart failure, recent myocardial infarction (<6 weeks), or known severe valvular disease.
10. Any other medical, surgical, or psychiatric condition that in the opinion of the investigator would place the patient at undue risk from study participation or interfere with the interpretation of study results.

• Study Protocol, Statistical Analysis Plan, and Informed Consent Form (PDF, 2025-10-15)