A free online resource for Intensive Care Medicine
Recently Updated Material
Transoesophageal echocardiography in the ICU
Sunday, October 31 (2021); Cardiology
The only question tagged as related to TOE in the cardiology revision section is Question 24 from the second paper of 2007, which asks the candidates to compare and contrast TTE and TOE in the evaluation of cardiac disease. In addition to this application, TOE has been compared to the PA catheter in the assessment of shock (Question 5 from the second paper of 2003) and to the aortogram in the evaluation of aortic dissection (Question 20 from the first paper of 2005, again in Question 13 from the second paper of 2010, and again in Question 24 from the first paper of 2015).
Staphylococcus aureus bacteraemia
Saturday, October 30 (2021); Infectious Disease Antibiotics and Sepsis
> S.aureus are gram-positive, catalase-positive, coagulase-positive cocci which produce severe infection with mortality ranging from 7-15% (CLAB, etc) to 60-70% mortality from infective endocarditis or lung abscess. S.aureus bacteraemia requires source control (eg. valve replacement or infected line removal) as well as antibiotic therapy for a minimum of 2 weeks for uncomplicated cases. Imaging, including contrast CT and echocardiography, is essential to rule out features of a "complicated" bacteraemia, eg. where there are septic emboli, CNS involvement or multiple sites of metastatic infection.
Distribution and regulation of magnesium in the body fluids
Wednesday, October 27 (2021); Body fluids and electrolytes
Magnesium is a divalent cation with mainly intracellular distribution, where its concentration is about 15-20 mmol/L. Most of the body store of magnesium remains in bone. The extracellular concentration is mainly regulated by a renal elimination mechanism which is sensitive to plasma levels.
Response to 1L of 5% dextrose
Saturday, October 23 (2021);
These are the physiological effects of infusing one litre of 5% dextrose into a patient.
Hyperphosphataemia
Friday, October 22 (2021); Electrolytes and Fluids
Phosphate disturbances are thankfully neglected in CICM SAQs. Fortunately for us all, up until Question 20.1 in the first paper of 2017 the college had never asked any questions about it. It appears in the Required Reading section purely for completeness (though the author is acute aware that the pursuit of completeness may lead one to contemplate disorders of molybdenum homeostasis, etc). Oh's Manual dwells briefly on phosphate and offers two Blue Boxes to describe its behaviour (Boxes 93.8 and 93.9, p. 957-958). Of the published literature, the best summary is offered by UpToDate. A highly detailed discussion is available behind another paywall, at Springer (Albaaj et al, 2003). Of free resources, the best turned out to be the eMedicine (Medscape) article by Eleanor Lederer and Vecihi Batuman (2015).
Mechanisms of ventilator breath triggering
Friday, October 22 (2021); Respiratory Medicine and Mechanical Ventilation
This has come up in Question 18 from the second paper of 2015. The college wanted a thorough discussion of the mechanisms of triggering and cycling. Overall, the question seemed like a refugee from the primary exam. The trainees answered it well (maximum mark was 8.5 and 77% passed), but the college still complained that "overall there was a lack of knowledge". Triggering of ventilation is subjected to a more thorough dissection in the Mechanical Ventilation section among the core topics. Here, only a brief summary is offered.
The expiratory and inspiratory process
Tuesday, October 19 (2021); Respiratory system
The normal mechanics of breathing can be described in terms of diaphragm, chest wall, pleural pressures and airflow. During inspiration, as the thoracic volume expands under the influence of respiratory muscle activity, the pleural pressure becomes more negative and generates a pressure gradient between the airway and the alveoli, which promotes inspiratory airflow. At the end of inspiration alveolar pressure equalises with atmospheric pressure, and there is no flow. During expiration, with relaxation of respiratory muscle, the thoracic volume decreases and the alveolar pressure exceeds atmospheric pressure, promoting expiratory air flow.
Interpreting the shape of the ventilator flow waveform
Saturday, October 16 (2021); Respiratory system
The flow waveform is the most interesting waveform. Much information can be derived from its shape. When flow is being used to generate a controlled level of pressure, the shape of the inspiratory flow waveform is informative regarding the necessary inspiratory time (if flow reaches zero, then the inspiratory time could be shorter without compromising volume). The expiratory flow pattern is also informative, as a slow return to baseline is an indication of the resistance to airflow.
Selective digestive tract decontamination (SDD)
Friday, October 15 (2021); Infectious Disease Antibiotics and Sepsis
Question 14 from the second paper of 2013 asks for a substantial amount of detail regarding SDD. A quick answer to "critically evaluate the role of SDD" can be found in the Discussion section there. Below is a long-form summary of recent evidence for SDD. Most of the information here has been summarised from a BMJ meta-analysis by the SuDDICU collaborators, as well as the excellent LITFL CCC archive entry for SDD.
Necrotising fasciitis
Friday, October 15 (2021); Infectious Disease Antibiotics and Sepsis
The college loves this condition, and it crops up rather regularly. Necrotising fasciitis in the human leg is explored in Question 24 from the first paper of 2011 (a diabetic leg) and Question 1 from the first paper of 2001 (a non-diabetic leg). Post-laparotomy necrotising fasciitis of the abdominal wall is seen in Question 25.1 from the first paper of 2009 and Question 3.2 from the first paper of 2014. Fournier's Gangrene is visited in Question 14.1 from the second paper of 2010.
Brain herniation
Friday, October 15 (2021); Neurology and Neurosurgery
Brain herniation can be subfalcine herniation, lateral ("midline shift"), uncal, tonsillar, upward or downward central transtentorial, or transcalvarial (i.e. out of a defect in the skull). Coma seems to be a common feature, and in most (unilateral) cases there is a ipsilateral third nerve palsy with the affected eye not doing very much in response to a doll's eye manoeuvre. There is, of course, more detail. The following point-form summary takes the salient features of Plum and Posner, adding various bits of wisdom from Radiopedia.org and whatever other web pundits had to say about this topic.
Decompressive craniectomy for traumatic brain injury
Friday, October 15 (2021); Neurology and Neurosurgery
Removing some of the skull is a neat way of cheating the Monro-Kellie doctrine. Pity it does you no favours. LITFL have an excellent page devoted to this practice. Additionally, an article directed at neurosurgeons is available and it highlights all the important features. Decompressive craniectomy (not specifically in TBI) was the subject of in Question 9 from the first paper of 2009, and its use in malignant MCA infarction appeared in Question 2 from the second paper of 2014.
Chylothorax- diagnosis and management
Friday, October 15 (2021); Cardiothoracic Intensive Care
Of all the body fluids which one might reasonably expect to drain from the chest cavity, chyle is among the most exotic, though it cannot share the pedestal with such oddities as urinothorax because chyle legitemately belongs in the chest cavity. It is the content of the thoracic duct which has the misfortune of being wrapped around structures of surgical interest. As such, it is frequently brutalised on the way to the oesophagus, pericardium, hiatus hernia or hilar lung tumour.
Pressure-volume and flow-volume loops
Friday, October 15 (2021); Respiratory Medicine and Mechanical Ventilation
This comes up a lot, but unlike ventilator waveforms the loops are not a part of the ICU routine. In fact the analysis of pressure-volume and flow-volume loops adds little to one's management. For instance, unreliablility of pressure-volume loops has been demonstrated in the context of determining the ideal PEEP in ARDS. Usually, the college expects the candidates to draw the pressure-volume curves of a patient with reduced compliance (compared to normal), and the flow-volume graphics tend to be the "scooped out" loops of bronschospasm.