Case Presentation: A man in his 20s with morbid obesity presented to an urgent care center with a sudden onset of fever, cough and shortness of breath (SOB). He was noted to have wheezing and received nebulized albuterol for presumed “new onset” bronchial asthma. He reported improvement in symptoms and was subsequently discharged. He visited a different emergency room two days later with worsening SOB and notable wheezing. His peak flow was significantly reduced at 100L/min. He was treated with nebulized albuterol and ipratropium, parenteral steroids and placed on non-invasive mechanical ventilation for asthma exacerbation. However, his course was complicated by respiratory failure and refractory shock. He was transferred to our intensive care unit (ICU) for extracorporeal membrane oxygenation (ECMO). In the ICU his management was directed at “refractory asthma”. In search for a trigger, a respiratory viral panel was sent and was positive for rhinovirus. A diagnosis of pneumonia (PNA) was entertained based on a radiologic opacification noted on day three of admission. A respiratory culture was sent that grew Moraxella catarrhalis and he was started on ceftriaxone for PNA. Serial x-rays showed resolution of opacification in two days. An echocardiogram was normal. After being on ECMO for 5 days his oxygenation improved and was transferred to the medical floor.
He was re-evaluated as a case of dyspnea with sudden onset wheezing and a CT pulmonary angiogram was done which showed bilateral segmental pulmonary embolism with high clot burden.

Discussion: Physicians use a wide cognitive toolset as part of the medical decision-making process. Heuristics are commonly employed cognitive methods which involve rapid associations of presenting cues to arrive at a diagnosis. These lead to efficient decision-making with less memory strain than the more analytical thought process. Although our patient had no known asthma, wheezing was reactively associated with asthma, leading to the working diagnosis of ‘asthma exacerbation’. A number of tests were then interpreted as supportive to the initial diagnosis including detection of rhinovirus and a fleeting opacity on x-ray. An important cause of acute wheezing is pulmonary embolism (PE). In the landmark studies done on symptomatology of PE it was shown that 16% of patients with PE had wheezing on presentation. The mechanism suggested is the release of serotonin from circulating platelets.
Another cognitive bias evident in this case is ‘anchoring’. It refers to our tendency as physicians to accept without question the initial diagnosis, often despite inconsistencies.

Conclusions: Heuristic medical decision-making and anchoring are cognitive biases that may lead to medical errors and adverse outcomes. Questioning our own rapid associations between symptoms and diagnoses, and revisiting our initial diagnosis, are paramount – as ‘all that wheezes is not asthma’.