Steroid isolation , depending on context, is the isolation of chemical matter required for chemical structure elucidation, derivitzation or degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but often more  or the isolation of "analytical quantities" of the substance of interest (where the focus is on identifying and quantifying the substance (for example, in biological tissue or fluid). The amount isolated depends on the analytical method, but is generally less than one microgram.  [ page needed ] The methods of isolation to achieve the two scales of product are distinct, but include extraction , precipitation, adsorption , chromatography , and crystallization . In both cases, the isolated substance is purified to chemical homogeneity; combined separation and analytical methods, such as LC-MS , are chosen to be "orthogonal"—achieving their separations based on distinct modes of interaction between substance and isolating matrix—to detect a single species in the pure sample. Structure determination refers to the methods to determine the chemical structure of an isolated pure steroid, using an evolving array of chemical and physical methods which have included NMR and small-molecule crystallography .  : 10–19 Methods of analysis overlap both of the above areas, emphasizing analytical methods to determining if a steroid is present in a mixture and determining its quantity. 
Endotracheal intubation and ventilation for impending respiratory failure:
Intubation and mechanical ventilation can be life-saving interventions but their use in paediatric patients with asthma have been associated with significant adverse effects. Up to 26% of children intubated due to asthma have complications, such as pneumothorax or impaired venous return, and cardiovascular collapse because of increased intrathoracic pressure  . Mechanical ventilation during an asthma exacerbation is associated with increased risk of death and should be considered as a last resort and only in conjunction with the support of a paediatric ICU specialist.
Narrative: Chronic obstructive pulmonary disease (COPD), a term that encompasses both patients diagnosed with chronic bronchitis and emphysema, is an obstructive lung disease in many cases caused by years of tobacco smoking. It is thought that patients with COPD ‘exacerbation’ (increased shortness of breath or change in their chronic cough and sputum) may benefit from steroids, presumably by reducing the inflammatory response that accompanies the exacerbation.
Benefits: 10 studies contributed data for this Cochrane analysis, representing 1051 patients. There was no statistically significant difference in the mortality of subjects who received systemic steroids compared to placebo. In regards to treatment failure, the review found a NNT of 10 (% reduction). Interestingly, no benefit was found in analysis of studies with steroids for less than 72 hours. The reductions in treatment failure were recorded from studies including both admitted and outpatient/Emergency Department patients.
Harms: Corticosteroids can cause multiple side effects, and some studies evaluated harms, though this was inconsistent across studies. When harms were pooled, there was an absolute risk increase of % for patients receiving steroids (NNH = 7) though this includes some harms that are not patient-oriented (high blood sugars) as well as some that are patient-oriented (diarrhea).