For patients over the age of 50 years suspected of having VTE with a low pretest probability, increasing the D-dimer cut-off level to 5× the age increases the proportion of patients in whom VTE can safely be excluded without radiological imaging.

The PERC rule has a high negative predictive value for excluding PE in patients presenting with suspected PE to the ED. However, the PERC rule may still miss around 8% of confirmed PE in patients who are deemed 'PE unlikely' by a dichotomized Wells score. Caution is advised in using the PERC rule as a substitute for the standard D-dimer test in all these patients.

A shortcut review was carried out to establish whether a higher age related threshold can be used when using d-dimer as a rule out test for pulmonary embolism. 29 papers were found of which 13 presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these best papers are tabulated. The clinical bottom line is that in older patients suspected of having a Pulmonary Embolus (PE), with a low pretest possibility, an age-adjusted D-dimer increases specificity with minimal change in the sensitivity, thereby increasing the number of patients who can be safely discharged without further investigations.

A case report on a 36-year-old male patient presenting to the emergency department (ED) with chest tightness, nasal sounding voice and subcutaneous emphysema 72 hours after the nasal insufflation of approximately 0.5g of cocaine. A plain radiograph of the chest demonstrated an extensive pneumomediastinum with subcutaneous emphysema extending into his neck. A computerised tomography (CT) scan confirmed the above findings, along with a pneumorrhachis of the thoracic spine. He was admitted locally for further investigation and observation. Cocaine is the second most used illicit drug in the UK. The associated complications of cocaine can vary from acute coronary syndrome to acute psychosis. Pulmonological trauma secondary to cocaine misuse is commonly associated with inhalation of cocaine; we present this rare case of subcutaneous emphysema, pneumomediastinum and pneumorrhachis secondary to nasal insufflation. It is believed that deep nasal insufflation of cocaine is followed by forceful Valsalva manoeuvre, which allows for the rapid absorption of the drug and increases the euphoric effect. This forceful inhalation can lead to barotrauma and leakage of air into the posterior mediastinum.