A free online resource for Intensive Care Medicine.
An unofficial Fellowship Exam (CICM Part 2) preparation resource.
Deranged Physiologyis a slowly growing archive of discussions and study notes relevant (or if not relevant, then at least interesting) to the practice of intensive care medicine. The content provides an introduction to the fundamental themes in intensive care: mechanical ventilation, vasopressors, electrolyte management, hemodynamic monitoring, dialysis, and so forth. Attention is directed at equipment in intensive care, and there are attempts to revisit interesting pharmacology and physiology. The aim of this resource is to supplement the bedside teaching of senior staff, and to consolidate resources for intensive care trainees in the initial stages of their training.
Management of ARDS is not all flashy physiology and pressure-volume circus tricks. There are numerous supportive strategies which help the ARDS patient, working quietly in the background. Minimization of dead space ventilation improves CO2 clearance, and low-carbohydrate high-fat nutrition decreases CO2 production. Neuromuscular blockade improves both survival and gas exchange (according to solid trial evidence). Good sedation decreases energy expenditure and improves ventilator synchrony, and neutral-to-negative fluid management improves gas exchange.
This issue has yet to appear in any great detal in the CICM Part II. Question 21 from the first paper of 2016 asked about its use as a supportive strategey for ARDS, but that's about it. However, its one of those things the ICU trainee is expected to know about.
The question of what to do with the patient who has presented within 4 hours of having a cerebral infarct is brought up inQuestion 22 from the first paper of 2013, "A 60-year-old male presents 2 hours after the onset of vertigo and loss of consciousness. CT brain is performed and shows right basilar and vertebral occlusion with no evidence of infarction. Discuss two possible definitive treatment strategies for this condition, including the indications and contra-indications of each."
However it is not as potent as adrenaline, because it is missing a hydroxyl group from its aromatic ring. The alpha selectivity is once again conferred by the methyl substitution hanging off the amine group.
Dobutamine is a synthetic catecholamine. As well as a well-defined catechol group, it possesses a humongous amine substituent group, which confer upon it a high level of beta-1 selectivity. This is the result of "intelligent drug design". The first paper to describe its properties (1975) is an amazing piece of work. The authors systematically produced a whole bucketfull of catecholamines with different side chains, amine substituents, hydroxyl group arrangements, etc etc - and then tested them for cardiovascular effect. Indeed, much of what we know about the structure and function relationship of catecholamines comes from such experiments.
This chapter is related to the aims of Section H3(i) from the 2017 CICM Primary Syllabus, which expects the exam candidate to "describe the principles of dialysis and renal replacement fluid". Extending this expectation ever so slightly, one could find the matter of circuit anticoagulation to be contain
There are numerous permutations of ventilator circuits, and of course ICU trainees are not expected to become familiar with all of them. The vast majority of the variants are relevant more to the anaesthetic environment, as their design is characterised by various attempts to conserve anaesthetic gas while discarding expired CO2. The breathing circuits used in Intensive Care are usually much more straightforward. This chapter has an ICUcentric focus, but the whole Mapleson family is still thoroughly explored.
Cardiac arrest following cardiac surgery is surprisingly uncommon, considering the fact that the heart was already quite diseased (hence it needed the surgery) and then it has been cut, grafted, manually handled and perfused with perverse fluids. Apparently in America the rate is about 0.7-0.8%, which means in a large hospital with a minimum turnover of 200-300 post-op cardiac surgical patients you'll end up doing this at least once or twice a year. This seems consistent with local experience. Given the frequency and importance of these events, it is surprising that the college has not thought to ask about it until Question 30.2 from the second paper of 2017.
Prognosis from accidental hypothermic cardiac arrest may be better than from "regular" cardiac arrest, perhaps by virtue of the fact that the hypothermia itself has some sort of intrinsic neuroprotective effect, or perhaps because the rescuers are always instructed not to give up until the patient is "warm and dead". Modifications to the BLS and ALS algorithm mainly concern the need to give drugs less frequently, and the need to rewarm as a priority.
In short,the pregnant patient in cardiac arrest requires several modifications to the cardiac arrest algorithm. These include performing cardiac compressions in a pelvic tilt position, using manual uterine displacement to relieve aortocaval compression, and proceeding quickly to a perimortem caesarian section. Question 9 from the first paper of 2016 explored these issues in detail. Specifically, the examiners were most interested in the esoteric topic of peri-mortem caesarian, and much less interested in the rather mundane practice of saving the pregnant cardiac arrest survivor.
Though the terms are often used interchangeably, dynamic hyperinflation and intrinsic PEEP are distinct entities. Dynamic hyperinflation is the increase in end-expiratory volume caused by incomplete end-expiratory emptying of the lungs, and intrinsic PEEP is the raised alveolar pressure during expiration which is caused by this progressive hyperinflation. This is usually caused by Increased airway resistance causing airflow limitation, but it can also happen due to an increased respiratory rate with insufficient time for alveolar emptying.
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.