Asthma therapeutic Flashcards
What features are suggestive of a severe asthma attack ?
Severe breathlessness and wheeze.
- -Agitation
- -Tachypnoeic (respiratory rate 34 breaths/minute),
- -Only able to talk in words rather than sentences
- -Hunched over and use of respiratory accessory muscles.
- -Reduced skin turgor suggesting dehydration due to fluid loss with panting.
- -Tachycardia 130/minute.
- -Pulsus paradoxus - systolic BP varied with respiration
- -Silent chest indicates very poor air entry to the alveoli
what is the pulsus paradoxus?
–An abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration. The normal fall in pressure is less than 10 mmHg. When the drop is more than 10mmHg, it is referred to as pulsus paradoxus
what is the mechanism of pulsus paradoxus?
–An exaggeration of the normal variation of BP with respiration. Normally during inspiration, systolic blood pressure decreases ≤10 mmHg, and pulse rate goes up slightly. This is because the intra-thoracic pressure becomes more negative relative to atmospheric pressure. This increases systemic venous return, so more blood flows into the right side of the heart. However, the decrease in intra-thoracic pressure also expands the compliant pulmonary vasculature. This increase in pulmonary blood capacity pools the blood in the lungs, and decreases pulmonary venous return, so flow is reduced to the left side of the heart. Also the increased systemic venous return to the right side of the heart expands the right heart and directly compromises filling of the left side of the heart. Reduced left-heart filling leads to a reduced stroke volume which manifests as a decrease in systolic blood pressure.
What investigations should be performed in a severe asthma attack?
1) Oxygen saturation
2) Arterial blood gases
3) Peak expiratory flow rate (PEFR) or FEV1
4) Chest X-ray to out-rule pneumothorax, and to check for infection and or lobar/segmental collapse.
5) Urea, Electrolytes, Creatinine – potassium, in particular, can be affected by anti-asthma therapy.
6) Full Blood Count – to check for evidence of infection
what electrolyte is particularly susceptible to anti-asthma meds?
potassium
what are the accident and emergency management of an acute severe attack?
- -High concentration oxygen (>60% oxygen if possible via face mask (aim O2 saturation > 95%)
- -Nebulised b2 agonists (salbutamol via oxygen driven nebulizer)
- -Nebulised muscarinic antagonist (ipratropium via oxygen driven nebulizer)
- -IV hydrocortisone
- -Correct fluid and electrolytes
in a severe asthma attack, oxygen treatment aims to increase the SpO2…
aim O2 saturation > 95%
what IV medication is crucial in a severe asthma attack?
IV glucocorticoids
in life-threatening cases of severe asthma attacks what measures should be added
- -Magnesium sulfate 2gm IV over 20 mins
- -IV aminophylline or salbutamol (not usually if high dose –nebulized b2 agonists used)
- -Intubation and Ventilation (ICU)
does MgSO4 is always used in a severe asthma attack?
only in life-threatening cases
do empiric antibiotics are recommended in a severe asthma attack?
: in the absence of evidence of infection, empiric antibiotics not recommended
what are the criteria to instigate mechanical ventilation in a patient with a severe asthma attack?
1) Increased distress and agitation
2) Confusion / drowsiness / exhaustion
3) Numbers not improving after initial therapy
- -If O2 saturation remained below 90%
- -If PEFR or FEV1 remained <50% of expected
- -If PCO2 climbed to >42 mm Hg.
Normal PCO2 or pH in a patient with severe asthma attack warrants intubation. True/False
True
Normal PCO2 indicates upcoming respiratory failure
Inhibition of phosphodiesterase mediated breakdown of cyclic AMP. describes what medications?
aminophylline and theophylline
Bronchodilation through activation of adenylate cyclase describes MOA of what med?
beta-2 agonists salbutamol, salmeterol, formeterol
