Editing Asthma (section)

====Asthma exacerbation<span class="anchor" id="Asthma attack"></span>====
<!--"Asthma attack" redirects here.-->
{| class="wikitable" style="clear:right; float:right; margin-left:15px; text-align:center"
|+ Severity of an acute exacerbation<ref name="BTS58" />
|-
! style="border-top:3px solid darkgrey;"| Near-fatal
| colspan="2" style="border-top:3px solid darkgrey;"| High [[Arterial blood gas|PaCO<sub>2</sub>]], or requiring mechanical ventilation, or both
|-
! rowspan="9" style="border-top:3px solid darkgrey;"| Life-threatening<br>(any one of)
|-
! Clinical signs
! Measurements
|-
| Altered [[level of consciousness]]
| [[Peak flow]] < 33%
|-
| Exhaustion
| [[Oxygen saturation]] < 92%
|-
| [[Heart arrhythmia|Arrhythmia]]
| [[Arterial blood gas|PaO<sub>2</sub>]] < 8 kPa
|-
| Low [[blood pressure]]
| "Normal" PaCO<sub>2</sub>
|-
| [[Cyanosis]]
|
|-
| Silent chest
|
|-
| Poor respiratory effort
|
|-
! rowspan="5" style="border-top:3px solid darkgrey;"| Acute severe<br>(any one of)
|-
| colspan="2" | Peak flow 33–50%
|-
| colspan="2" | Respiratory rate ≥ 25 breaths per minute
|-
| colspan="2" | Heart rate ≥ 110 beats per minute
|-
| colspan="2" | Unable to complete sentences in one breath
|-
! rowspan="3" style="border-top:3px solid darkgrey; border-bottom:3 px solid darkgrey;"| Moderate
| colspan="2" style="border-top:3px solid darkgrey;"| Worsening symptoms
|-
| colspan="2" | Peak flow 50–80% best or predicted
|-
| colspan="2" style="border-bottom:3 px solid darkgrey;"| No features of acute severe asthma
|}

An acute asthma exacerbation is commonly referred to as an '''asthma attack'''. The classic symptoms are [[shortness of breath]], [[Wheeze|wheezing]], and [[chest tightness]].<ref name=M38/> The wheezing is most often when breathing out.<ref>{{cite book |title=Current Review of Asthma |date=2003 |publisher=Current Medicine Group |location=London |isbn=978-1-4613-1095-2 |page=42 |url=https://books.google.com/books?id=MCEBCAAAQBAJ&pg=PA42 |url-status=live |archive-url=https://web.archive.org/web/20170908184941/https://books.google.com/books?id=MCEBCAAAQBAJ&pg=PA42 |archive-date=September 8, 2017 }}</ref> While these are the primary symptoms of asthma,<ref name=Barnes2008>{{cite book | vauthors = Barnes PJ |chapter=Asthma |title=Harrison's Principles of Internal Medicine |url=https://archive.org/details/harrisonsprincip00asfa |url-access=limited | veditors = Fauci AS, Braunwald E, Kasper DL |location=New York |publisher=McGraw-Hill |date=2008 |edition=17th |isbn=978-0-07-146633-2 |pages=[https://archive.org/details/harrisonsprincip00asfa/page/n1634 1596]–1607 }}</ref> some people present primarily with [[cough]]ing, and in severe cases, air motion may be significantly impaired such that no wheezing is heard.<ref name="BTS58" /> In children, [[Pediatric chest pain|chest pain]] is often present.<ref name="Mac2011">{{cite book |vauthors=McMahon M |title=Pediatrics a competency-based companion |publisher=Saunders/Elsevier |location=Philadelphia |date=2011 |isbn=978-1-4160-5350-7 }}</ref>

Signs occurring during an asthma attack include the use of accessory [[muscle]]s of respiration ([[sternocleidomastoid]] and [[scalene muscles]] of the neck), there may be a [[pulsus paradoxus|paradoxical pulse]] (a pulse that is weaker during inhalation and stronger during exhalation), and over-inflation of the chest.<ref name=Maitre1995>{{cite journal | vauthors = Maitre B, Similowski T, Derenne JP | title = Physical examination of the adult patient with respiratory diseases: inspection and palpation | journal = The European Respiratory Journal | volume = 8 | issue = 9 | pages = 1584–93 | date = September 1995 | doi = 10.1183/09031936.95.08091584 | pmid = 8575588 | s2cid = 30677275 | url = http://erj.ersjournals.com/content/8/9/1584.long | url-status = live | archive-url = https://web.archive.org/web/20150429223309/http://erj.ersjournals.com/content/8/9/1584.long | archive-date = April 29, 2015 | doi-access = free }}</ref> A [[cyanosis|blue colour]] of the skin and nails may occur from lack of oxygen.<ref name=Werner2001>{{cite journal | vauthors = Werner HA | title = Status asthmaticus in children: a review | journal = Chest | volume = 119 | issue = 6 | pages = 1913–29 | date = June 2001 | pmid = 11399724 | doi = 10.1378/chest.119.6.1913 }}</ref>

In a mild exacerbation the [[peak expiratory flow rate]] (PEFR) is ≥200&nbsp;L/min, or ≥50% of the predicted best.<ref name="Shiber2006">{{cite journal | vauthors = Shiber JR, Santana J | title = Dyspnea | journal = The Medical Clinics of North America | volume = 90 | issue = 3 | pages = 453–79 | date = May 2006 | pmid = 16473100 | doi = 10.1016/j.mcna.2005.11.006 }}</ref> Moderate is defined as between 80 and 200&nbsp;L/min, or 25% and 50% of the predicted best, while severe is defined as ≤&nbsp;80 L/min, or ≤25% of the predicted best.<ref name="Shiber2006" />

[[Acute severe asthma]], previously known as status asthmaticus, is an acute exacerbation of asthma that does not respond to standard treatments of bronchodilators and corticosteroids.<ref name=Shah2012/> Half of cases are due to infections with others caused by allergen, air pollution, or insufficient or inappropriate medication use.<ref name="Shah2012">{{cite journal | vauthors = Shah R, Saltoun CA | title = Chapter 14: Acute severe asthma (status asthmaticus) | journal = Allergy and Asthma Proceedings | volume = 33 | issue = 3 | pages = 47–50 |year=2012 | pmid = 22794687 | doi = 10.2500/aap.2012.33.3547 }}</ref>

[[Brittle asthma]] is a kind of asthma distinguishable by recurrent, severe attacks.<ref name=BTS58>{{harvnb|British Guideline|2009|p=54}}</ref> Type 1 brittle asthma is a disease with wide peak flow variability, despite intense medication. Type 2 brittle asthma is background well-controlled asthma with sudden severe exacerbations.<ref name=BTS58/>