The use of upper airway structures in a patient with a tracheostomy is a sort of delicate art, resembling the use of a brass or woodwind instrument, involving timing and the deliberate obstruction of various important fingerholes in order to produce speech. In the CICM Part II exam, this topic has come up as a whole 10-mark question (Question 17 from the first paper of 2017) as well as in the context of more equipment related discussions regarding Passy-Muir valves and suchlike.
Sympatholytic agents are those that inhibit the activation of the sympathetic nervous system. For many of them, the side effect profile has prevented widespread use. They consist of central agents such as clonidine and methyldopa, ganglionic blockers such as hexamethonium, catecholamine storage inhibitors such as reserpine, synthesis inhibitors such as methyltyrosine and direct receptor antagonists such as all the familiar beta blockers and alpha blockers.
Clonidine is a centrally acting α-2 agonist, an imidazoline derivative with antihypertensive analgesic and sedative effects. The antihypertensive effect is due to the presynaptic inhibition of noradrenaline release in the CNS.
Heart failure management is a massive daunting topic. In order to approach this in a systematic manner, I have separated the problems of heart failure into the variables which govern cardiac output, and the means of manipulating those variables. The approach resembles that of the similar chapter from the section on cardiothoracic intensive care. The definitive resource for this is probably this 2013 guideline statement by the AHA/ACC. Unless otherwise reported, it is my source for most of the information below. For the sane exam candidate who may be disinclined to read the entire fifty-page document, of particular interest may be Section 7.3.2, Pharmacological Treatment for Stage C HFrEF.
The question of glycaemic control in the critically ill- unlike many questions in ICU - can be answered with a single paper. However, the path we took to get to this answer is worth reviewing. LITFL has an excellent summary of the relevant literature, all together under one roof in their Glucose Control Literature Summaries. In short, any normal BSL below 10mmol/L seems to be fine, and trying to control things more finely than that will lead to an increased rate of complications. Past paper SAQs which asked about glycaeic control have included Question 23 from the first paper of 2005 and Question 7 from the first paper of 2002.
The modern concept of pH requires a primary method measurement in order to maintain validity as a definition. Specifically, some sort of method is required to calibrate standard buffer solutions, against which the pH of all substances can be measured. The experimental apparatus used by IUPAC to assign standard pH values to primary standard pH buffer solutions is based on the Harned cell.
Because the kidneys are responsible for the clearance of most drugs and their metabolites, renal clearance has the examiners' attention. The magnitude of renal drug clearance is the sum of glomerular filtration and active excretion, minus passive drug reabsorption by back-diffusion. The kidneys also metabolise some drugs (eg. imipenem) and they actively reabsorb others (eg. glucose and α-methyldopa). Dose adjustment for renal impairment concerns regular maintenance dosing; either the dose can be decreased, or the dosing interval can be increased, or potentially both.
Cyclic guanosine monophosphate is a cyclic nucleotide secondary messenger. It is produced when guanylyl cyclase is activated by nitric oxide, or by a natriuretic peptide. It is degraded by phosphodiesterases (some of which also degrade cAMP). Its main downstream target is Protein Kinase G (PKG) , which decreases IP3 activity, desensitises myofibrils to calcium, and decreases intracellular calcium availability by several other mechanisms. In summary, he net effect of cGMP secondary messenger activity is smooth muscle relaxation
The sympathetic nervous system is defined by the thoracic origin of its nerve fibres, which come out of T1-L1 nerve roots and form the sympathetic chain. Preganglionic neurotransmission is cholinergic, and postganglionic neurotransmission is noradrenergic, with the exception of muscarinic transmission of the fibres that innervate the eccrine sweat glands. The mostly proximal (paravertebral) positioning of the ganglia, forming two symmetrical chains, is a characteristic anatomical feature, distinct from the parasympathetic nervous system which has ganglia positioned closer to the target organ.
This is something of a summary of how catecholamines behave around adrenergic receptors. It describes catecholamine storage in vesicles, their exocytosis, presynaptic neurotransmission, and reuptake by NET ad DAT transporter proteins.
Immunosuppressant pharmacology is something of a niche topic which has been largely absent from the CICM exams. Its reappearance in the Fellowship exam clearly took a lot of people but surprise. This brief chapter is an answer to the CICM exam question on this topic, as well as a short review of immunosuppressants for the intyensivist.
This is an altered level of consciousness attributed to the consequences of acute or chronic liver failure. Ammonia is only one of the aetiological agents. But, it is certainly the one everyone always thinks of. Copious amounts of blood are being sent for ammonia levels every day. Surely, there must be some reason behind this. In order to derive some meaning from this seemingly mindless ammonia-lust, one must explore the mechanisms of metabolic derangement which arise within the liver failure patient.
Question 13.1 from the first paper of 2015 and Question 20 from the first paper of 2010 interrogated the candidate's understanding of propofol infusion syndrome. The pharmacology of propofol in a more general sense is explored in a chapter dedicated to that substance. Instead of going on at length about it, the focus of this brief summary is on the clinical features of propofol toxicity, as well as all the other minor stuff which was required to anwer the SAQs.