A 36 year old female is brought into your Emergency Department with acute shortness of breath. She is unable to provide any history due to her tachypnoea. She is sitting upright in bed grasping the bed sides. She has a respiratory rate of 30 breaths per minute, has a GCS of 15, is afebrile and has a BP of 90/60mmHg. She is using accessory muscles. On auscultation, she has widespread expiratory wheeze spread throughout both lung fields.
a) In addition to acute severe asthma, what other differential diagnoses of her clinical presentation should be considered?
b) Assuming this patient has acute severe asthma, list your initial management steps at this stage.
c) Despite optimal medical management, the patient tires. Briefly outline the role of BiPAP in acute severe asthma.
d) BiPAP fails and the patient is successfully intubated. Following intubation, airway pressures rise and the chest becomes more silent. List other interventions may you consider.
a) In addition to acute severe asthma, what other differential diagnoses of her clinical presentation should be considered?
Differential diagnoses
• anaphylaxis ( large % don’t have rash etc – just bronchospasm)
• Acute exacerbation COPD
• central foreign body
• acute pulmonary oedema
• Pneumothorax
• Hysterical hyperventilation
• acute Pulmonary embolus
b) Assuming this patient has acute severe asthma, list your initial management steps at this stage.
• Resuscitation/ investigation and definitive management
• Initial salbutamol nebulisation – continuously. Consider IV infusion
• IV steroids - ? type and dose .
• Replace K/Mg
• Nebulised adrenalin if anaphylaxis still under consideration
• IV access, bloods including mast cell tryptase cultures/ +/- procalcitonin
• Portable CXR to exclude pnemothorax / localised consolidation and assess hyperinflation.
c) Despite optimal medical management, the patient tires. Briefly outline the role of BiPAP in acute severe asthma.
Intrinisic PEEP increases the negative intrathoracic pressure the patient must generate to trigger a breath and hence increases WOB. Application of extrinsic PEEP minimises this difference and reduces WOB. IPAP reduces the WOB associated with resistance.
d) BiPAP fails and the patient is successfully intubated. Following intubation, airway pressures rise and the chest becomes more silent. List other interventions may you consider.
• Another CXR to check no PTX post PPV
• Increasing salbutamol
• Deepen sedation
• Adding adrenalin/ aminophylline/ ketamine/ Mg ( no evidence) – doses required by candidate
• Volatile anaesthesia
• Paralysis- Train of four essential .
• ? bronchoscopy
• Measurement of iPEEP
a) In addition to acute severe asthma, what other differential diagnoses of her clinical presentation should be considered?
This is a question about the differential diagnosis of wheeze.
There can be a myriad answers.
UpToDate even has a page about this sort of thing.
b) Assuming this patient has acute severe asthma, list your initial management steps at this stage.
This answer lends itself well to a systematic approach
b) Assuming this patient has acute severe asthma, list your initial management steps at this stage.
The usefulness of positive pressure ventilation in people with intrinsic PEPE is discussed elsewhere.
In summary, positive pressure ventilation decreases effort of breating by applying a positive counter-pressure and thus decreasing the relative amount of intrathoracic pressure which must be generated by the patient's muscles. This decreases the work of breathing. Additionally, it splints the constricted airways, allowing improved CO2 clearance. IPAP increases the pressure gradient during inspiration, improving the flow of gas agains the resistance of the constricted airways. The tight-fitting mask ensures a consistent delivery of the prescribed FiO2.
d) BiPAP fails and the patient is successfully intubated. Following intubation, airway pressures rise and the chest becomes more silent. List other interventions may you consider.
UpToDate: Evaluation of wheezing illness other than asthma in adults
Oddo, Mauro, et al. "Management of mechanical ventilation in acute severe asthma: practical aspects." Intensive care medicine 32.4 (2006): 501-510.
Phipps, P., and C. S. Garrard. "The pulmonary physician in critical care• 12: Acute severe asthma in the intensive care unit." Thorax 58.1 (2003): 81-88.