Deranged Physiology

Questions about PE are frequent. Usually, they ask about the acute management of a haemodynamically unstable pulmonary embolism. The examiners seem to have a particular interest in thrombolysis. The best references for answering such SAQs are probably the 2014 ESC guidelines and 2012 ACCP Guidelines.

In the CICM part II exam, this does not come up nearly as often as it does in real life. Specifically, Question 2 from the first paper of 2017 had presented the candidates with an ECG of a patient suffering from complete heart block after being dosed with both sotalol and verapamil. It was given to her by well-meaning radiology technicians who just wanted to get some nice CT images of her coronaries. The more conventional scenario for this is a patient being treated for refractory rapid atrial fibrillation, who ends up on multiple agents and becomes haemodynamically unstable from complete heart block. The college have only ever explored this in the context of a CCB/β-B cocktail, and so the majority of this chapter will be dedicated to this specific problem, and its management. Other more exotic combinations make for an interesting digression, but do not form a part of core CICM exam preparation, and can be safely ignored forever.

Calcium channel blocker overdose has rarely appeared in the CICM Part II exam. For instance, Question 2 from the first paper of 2017 had presented the candidates with an ECG of a patient suffering from complete heart block after being dosed with both sotalol and verapamil, something best discussed in the chapter on toxic antiarrhythmic polypharmacy. In another example, Question 14 from the second paper of 2006 asked the candidates to compare beta blockers and calcium channel blockers in a "compare and contrast" table. An ideal resource for answering such a question can be found in DeWitt and Waksman's article from Toxicological reviews (2004) - they basically answer the college question for you. The cardinal differences in these two  toxicological syndromes are discussed at the very end of this chapter, which otherwise mainly deals with calcium channel blockers on their own. Additional resources should include the LITFL CCC entry, which is clear and concise.

Beta blocker overdose has rarely appeared in the CICM Part II exam. For instance, Question 2 from the first paper of 2017 had presented the candidates with an ECG of a patient suffering from complete heart block after being dosed with both sotalol and verapamil, something best discussed in the chapter on toxic antiarrhythmic polypharmacy. In another example, Question 14 from the second paper of 2006 asked the candidates to compare beta blockers and calcium channel blockers in a "compare and contrast" table. An ideal resource for answering such a question can be found in DeWitt and Waksman's article from Toxicological reviews (2004) - they basically answer the college question for you. The cardinal differences in these two  toxicological syndromes are discussed at the very end of this chapter, which otherwise mainly deals with beta-blockers on their own. Additional resources should include the LITFL CCC entry, which is clear and concise.

This chapter deals with the investigations and resuscitation of massive gastrointestinal bleeding.  For the purposes of having a firm definition, anything below the ligament of Treitz is taken as the "lower" tract. In terms of relevance for the CICM fellowship, massive GI bleeding is probably not a high-yield subject matter (even though it forms a major part of our daily workload). Historically, it has appeared in several SAQs. Question 1 from the first paper of 2017 was all about the causes and management of a massive variceal haemorrhage. The much older  Question 1a and Question 1b from the second paper of 2001 also offered us an exsanguinating alcoholic, but the real fun began when in the last part of the SAQ the wife asked whether he was going to survive (see Staging and prognosis of chronic liver disease in ICU).

These are the physiological effects of infusing 100ml of concentrated (20%) human albumin into a patient. 20% albumin is a sticky protein concentrate with a variable amount (48-100mmol/L) of sodium in it. Following the early pioneers, in 1976 post-op patients were infused with 50g of albumin in varying concentrations. The volume expansion for all these patients was about 500ml, working out to be 11ml of volume expansion per 1g of "retained" albumin (i.e. accounting for some "escaped" albumin). A similar study had later confirmed these findings in a group of bypass patients, arriving at a figure of 7.7ml volume expansion per 1g of albumin.

Acute status asthmaticus is a fragile thing which, most ICU specialists would agree, is a good reason to get out of bed and drive to the hospital. These people tend to die rather readily, typically of cardiac arrest due to dynamic hyperinflation and the resulting loss of preload. This is made worse by the fact that the excellent outpatient management of asthma has filtered out the mild and moderate patient groups, and left only the incredibly brittle severe asthmatics. Only these are the people who ever get admitted to ICU for mechanical ventilation. Thankfully, even the ICU management of these people is improving, and in spite of an overall worsening severity of their illness, their ICU mortality has been steadily improving.

These are the circuit of an externalised artificial cardiac conduction system. The difference between these systems is mainly impedance, and the amount of required current. A bipolar circuit has both the electrode inside the heart, with the heart muscle and intraventricular blood completing the circuit. A unipolar circuit on the other hand relies on a large amount of tissue and body fluid to complete the circuit, and therefore has a much higher impedance. In the majority of situations these days the bipolar circuit is favoured. There is much less electrical interference and substantially less current is required.

There are a few ways of estimating the energy requirements of a critically ill patient: crudely (25kcal/kg/day), using predictive equations, using the reverse Fick method, or using indirect calorimetry. The resting energy expenditure achieved by the use of a predictive equation may be multiplied by 1.2 to factor in a mildly increased level of stress, and by 1.9 to factor in a severe hypercatabolic state. The average critically ill patient requires 400-700g/day of glucose, 1.5-2.0g/kg/day of protein, and 0.7-1.5g/kg/day of lipid. The carbohydrate:fat ratio should be around 70:30, to maintain a respiratory quotient (RQ) in the range of 0.85-0.9 (though this recommendation lacks firm scientific foundation).

 This topic has never become a CICM SAQ but is sufficiently awesome to merit a whole long discussion.  This "storm" concept has no fixed scientific definition.  VT storm can be managed with drugs, of which the first line agents are amiodarone, lignocaine and beta-blockers. Second line drug therapy may include phenytoin and other class 1 agents like mexilitine. Cardioversion and overdrive pacing are valid options. Lastly, one may resort to stellate ganglion blockade, thoracic epidural, and radiofrequency ablation. Invasive surgical procedures like thoracic sympathectomy and endocardial resection are reserved for special cases which can benefit from neither drugs nor RFA.