An 82-year-old male has been cleared for discharge to the ward after spending three weeks in your ICU for a large subdural haemorrhage. A junior nurse gave him a trial of oral feeding and then removed his right subclavian vein catheter. Subsequently, he became cyanosed and suffered a bradycardic/asystolic cardiac arrest.
Following successful resuscitation and orotracheal intubation, his observations are as follows: Heart rate: 135 beats/min (sinus)
Blood pressure: 120/72 mmHg on noradrenaline 20 mcg/min Oxygen saturation of 90% on FiO2 0.8
a) List two likely differential diagnoses that best explain the events. (20% marks)
b) Outline your diagnostic approach to distinguish between them. (40% marks)
c) Briefly outline the specific management for each of your diagnoses. (40% marks)
- One mark each for the following diagnoses (only count first 2 listed by candidate)
- Air embolism
- Aspiration pneumonitis/pneumonia
- Pulmonary embolus
- For each diagnosis 2 marks for clear and concise diagnostic strategy:
- 1 mark for appropriate history and examination features
- 1 mark for specific investigations
History of unclamped line especially in upright position, sudden onset typically. Exam may reveal ‘Mill Wheel’ murmur
Investigation: Echocardiography to reveal air in cardiac chambers
History: May be witnessed, hypoxia after eating/drinking
Exam: Signs of consolidation/collapse (crackles, bronchial breathing etc.) Investigations: CXR usually sufficient, OK to mention US
History: risk factors, sudden onset, chest pain, SOB
Exam: usually nil specific, absence of alternative diagnostic signs e.g. normal auscultation Investigations: CTPA confirmatory if stable enough for transport, Echo highly suggestive in correct clinical setting and occasional visualise thrombus.
- Clear specific, safe, sensible management strategy = 2 marks for each condition. 1 = partial detail or lacking clinical perspective
Occlude CVC site
Head down / Trendelenberg position Catheter aspiration
Consider hyperbaric when haemodynamically stable especially if neurological symptoms and signs
Bronchoscopy if large volume or bronchial obstruction
Antibiotics for secondary infection
Consider embolectomy or catheter directed clot retrieval if available.
Thrombolysis may be considered even in cases of massive PE even with recent surgery if death otherwise imminent, balance risk of bleeding vs. death by PE on case-by-case basis.
Anticoagulation with Heparin/Clexane depending on perceived risk of bleeding
This is one of those things that might work better as a table:
Muth, Claus M., and Erik S. Shank. "Gas embolism." New England Journal of Medicine 342.7 (2000): 476-482.
Palmon, Sally C., et al. "Venous air embolism: a review." Journal of clinical anesthesia 9.3 (1997): 251-257.
Oh's Intensive Care manual: Chapter 34 (pp. 392) Pulmonary embolism by Andrew R Davies and David V Pilcher
Anderson, Frederick A., and Frederick A. Spencer. "Risk factors for venous thromboembolism." Circulation 107.23 suppl 1 (2003): I-9.
Konstantinides, Stavros V., et al. "2014 ESC Guidelines on the diagnosis and management of acute pulmonary embolism." European Heart Journal (2014): ehu283.