CHAPTER 57: Status Asthmaticus

KEY POINTS

• Critical asthma syndrome (CAS) represents the most severe subset of asthma exacerbations requiring hospital-based care. Status asthmaticus is subsumed under the term CAS and is defined as a sudden or prolonged exacerbation marked by continuous dyspnea to the point of exhaustion, not readily relieved with escalation of rescue treatments in the hospital. Near-fatal asthma is status asthmaticus that has progressed to acute respiratory failure, which can end in fatal asthma.

• The imminent danger during status asthmaticus is unrecognized or sustained cerebral hypoxia due to acute respiratory failure. Profound fatigue and exhaustion for days and even cardiopulmonary arrest before hospital admission contribute to the acute danger. Pre-exisiting conditions, eg, cardiovascular disease, COPD, bronchiectasis, obesity, diabetes mellitus, and Cushing’s syndrome may extend and complicate the hospital course. All aspects of recognition, treatment, and critical care management of status asthmaticus must be patient-centric, safe, and evidence-based.

• The death rate from asthma globally has not declined since 2006. The number of deaths in adults from status asthmaticus in the United States continues to exceed 4000 per year (approximately 10 deaths per million) despite critical care practices relying on evidence-based national and global asthma guidelines for the past three decades. Reasons may include clinical heterogeneity of asthma phenotypes and endotypes (phenotypes defined by disease mechanisms); variable response to pharmacotherapy; team inexperience in managing CAS, and failure by patients, physicians, and advanced practice providers to recognize status asthmaticus early and prior to hospitalization.

• Mortality in adults from asthma in the United States is highest among African Americans, Puerto Rican-Americans, women, and those 65 years and older. However, Asians are more likely to die during asthma-related hospitalizations.

• The average hospital length of stay (LOS) is 3.9 days for status asthmaticus, but 8.3 days for mechanically ventilated or intubated patients—multivariate predictors of high LOS included white race, increasing age, and winter hospitalizations. Between 5% and 10% of hospitalized will require ICU. Overall, in-hospital mortality is 1% and as high as 9.8% in patients requiring mechanical ventilation and/or intubation. Age, hospital admissions during winter months, and type of health care insurance are independent risk factors for in-hospital mortality.

• CAS always begins with an exacerbation. The terms severe exacerbation or serious exacerbation fail to describe how acutely life-threatening CAS can be to the patient. The pillars of CAS pathophysiology remain airway inflammation, smooth muscle bronchoconstriction, and mucus plugging to varying degrees, but an understanding of pathobiology may help clinicians better manage and treat patients who continue to deteriorate in hospital despite receiving oxygen, bronchodilators, and systemic, or oral corticosteroids (OCS).

• Viral infections are the most common trigger for exacerbations and CAS, in particular rhinovirus and influenza. Hospitalization rates for exacerbations by seasons correlate with viral upper respiratory infections. Noninfectious causes include environmental allergens or pollutants (eg, ozone, caustic chemicals, tobacco smoke, wildfire air pollution), drugs (aspirin, nonsteroidal anti-inflammatory drugs, recreational drugs) and nonadherence to asthma treatments. Adverse drug effects from inhaled corticosteroids (ICS) can compound the risk of ...