Clinical Presentation

Asthma presentations vary widely along a spectrum. The mildest attacks may present only as a persistent cough while the worst attacks result in cardiac arrest.

A common presentation is one with a sensation of chest tightness, dyspnea and wheezes.

Wheezing is indicative of airway obstruction but beware of the absence of wheezing too. Silence can indicate respiratory arrest.

As mild attacks transition to moderate or severe, signs like “tripod” positioning, accessory muscle use, retractions and nasal flaring begin to occur.

As the case worsens, wheezes initially become louder. However, the air exchange can be disrupted to the point that air no longer reaches the bases of the lungs. When air no longer reaches the bases, the wheezes are no longer heard. This loss of wheezes may progress cephalically until the lungs are completely silent

Breathing becomes very difficult and the use of accesory muscles only serves to increase oxygen demand and fatigue. The fatiguing patient is at risk of requiring intubation and postiive pressure ventilation to support their ventilatory effort.

“Breath stacking” (dynamic hyperinflation) occurs when air becomes trapped below the narrowed airways increasing the residual volume. 

This increases intrathoracic pressure and requires increasing effort to breathe! (this is when accesory muscles are recruited)

At this stage, anxiety is becoming a real threat by causing short and rapid breaths. This has the effect of shortening expiratory time and thereby reducing the amount of air that the patient can exhale!

The sloped ascending phase of the “sharkfin” capnograph is the result of the slowed emptying of the lungs.

If the “peak expiratory flow rate” (PEF) is sufficiently reduced (50%) this is actually part of the definition of a SEVERE asthma attack. 

A worsening condition may be recognized by tachypnea progressing to bradypnea or by

“See-saw” breathing

Pulsus paradoxus

Cyanosis, Lethargy

Confusion Anxiety!

Rising EtCO2

Falling SpO2

Hemodynamic Compromise!

An expired CO2 value of >45mmHg or

A respiratory rate >30 breaths per minute

Are indications of severe respiratory distress!

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