Update quiz June 2014

The presence of cardiac contusion in haemodynamically stable patients is of almost no clinical significance due to the absence of delayed serious arrhythmias or other complications when present. Normal contractility on echocardiography reliably excludes a clinically significant cardiac contusion, irrespective of ECG or troponin changes. The ECG is used to exclude concomitant myocardial infarction or pre-existent cardiac arrhythmias, however most ST changes are usually non specific, especially if pulmonary injury present. Serum troponin is not routinely required but may be of limited value in the presence of haemodynamic instability if echocardiography is unavailable. Troponin levels ≥ 0.1 microg/L are approximately 25% sensitive, 95% specific for cardiac contusion in the haemodynamically stable patient with sternal fracture. (link)

Asymptomatic AVMs rupture at a rate of approximately 1%/year. Leakage is usually at the venous end of the AVM, so bleeding is usually less severe that for arterial SAH. Conservative management has been shown in a RCT to be superior to active management for asymptomatic AVMs. Parenchymal AVMs are more common than meningeal or dural AVMs although may have some dural involvement. 80% of them are found above the tentorium. (link)

Uterine blood flow at term is approximately 500 mL/min. Uterine contractions usually cause a decrease in oxygen saturation of the maternal blood then return to precontraction levels. Uterine contractions cause a 15% decrease in maternal heart rate and an increase in maternal stroke volume by 35% due to increased venous return. The net effect of this is that maternal cardiac output increases during a uterine contraction. (link)

The DIC scoring system is used to help determine if DIC is present. It is comprised of the following elements: platelet count –  50,000 – 100,000 per mm3 = 1 point, < 50,000 per mm3 = 2 points; D dimer or FDPs – normal = 0 points, moderate increase = 2 points, large increase = 3 points: prothrombin time – < 3 sec = 0 points, ≥3 < 6 sec = 1 point, ≥6 sec = 2 points; fibrinogen – ≥1 g/L = 0 points, <1 g/L = 1 point. A score of ≥5 points is compatible with overt DIC whilst a score of < 5 points suggests nonovert DIC. A D dimer level of 4 is considered a large increase, with levels > 2 usually present in DIC. (link)

The important things to determine about any pacemaker are: the device manufacturer and model; who controls the device; if your hospital has programmer for this make and model, the effect of using magnet mode and the native, non paced rhythm. In this case the native rhythm is the most important to know as if it is a haemodynamically very unstable rhythm (e.g. ventricular standstill), then you will need to have a suitable backup pacemaker in place before you turn off the pacemaker. (link)

Fluid restriction in this setting will be too slow to take effect and is not generally very effective. NSaline administration may increase the sodium slightly but the amounts of NSaline required to correct severe hyponatraemia may lead to oedema, and may also be too slow in effect. As a temporary measure it has the advantage of being able to be given immediately through a peripheral line. A fixed dose of hypertonic saline is the preferred management because using a calculated Na doses appears to correct the serum sodium excessively. (link)

Total osmolality is the concentration of all solutes in a given weight of water (mOsm/kg), regardless of whether or not the osmoles can move across biological membranes. Effective osmolality is the number of osmoles that contribute water movement between the intracellular and extracellular compartment. It is a function of the relative solute permeability properties of the membranes separating the intracellular and extracellular fluid compartments. Urea is an ineffective osmotic substance (as it crosses membranes freely) so does not contribute to effective osmolality. Effective osmolality is also known as tonicity. (link)

The Hunter criteria for the diagnosis of Serotonin syndrome are all clinical features. They are: the presence of clonus and agitation or sweating or hypertonia and T > 38C indicating serotonin toxicity (in patients with an apppropriate history); tremor and hyperreflexia.(link)

Following a surgical termination of pregnancy, intermittent vaginal bleeding may occur for 2-3 weeks, however it is usually of less volume than a normal period. Prolonged bleeding or ongoing pain may indicate incomplete evacuation of products or uterine perforation as only mild pain should be expected. Pregnancy symptoms usually subside within 3 days and the urine BHCG are still inconclusive or falsely positive 66% and 20% of the time at 2 and 4 weeks respectively. (link)

Lymphopenia is a common, incidental finding of no particular significance, particularly in the elderly and is present in 1-3% of FBE samples. It does not require further investigation if the patient is otherwise well and has a count > 0.5 X 10-9/L in the elderly or 1 X 10-9/L in younger patients. It is usually due to a reduction in T Cells (normally 60-80% of circulating lymphocytes). Sepsis is the most common cause of counts < 0.6 X 10-9/L in hospitalised patients. In HIV, a lymphocyte count < 1,200 is 45% sensitive, 95% specific for a CD4 count of < 350 and 50% of patients with newly diagnosed HIV have a lymphocyte count < 1.5 X 10-9/L. (link)

The approximate risk of DVT in patients with a Modified Wells score of 1 or less is estimated to be between 3-9%. (link)

The risk of DVT in patients with a Modified Wells score of 2 or more is approximately 20-35% overall. (link)

Bitumen burns should be soaked with cooled water for at least 20 min, but adherent clothing should not be removed as this may cause tissue damage. Tar should not be removed directly as it is usually adherent to underlying tissues. Initial management may include: dressing with tulle gras over the burn; soaking  in olive oil, liquid paraffin oil, petroleum based jelly or De-solv-it (a commercially available citrus based solvent) to remove the tar. Alcohol, acetone or harsh organic hydrocarbon solvents such as kerosene or gasoline should not be used as they worsen injury. Chemical debridement may take days to complete. Circumferential burns require transverse splitting of the bitumen as it will constrict on cooling. Extensive or full thickness burns require surgical debridement in the OT in combination with chemical debridement. (link)

A systematic review concluded there is insufficient evidence to conclude that spectrophotometry is superior to visual inspection. Sensitivity of both for SAH is approximately 85%, with spectrophotometry possibly marginally more sensitive than visual inspection, however time from event to LP in these studies not known. Specificity is approximately 85% for spectrophotometry and closer to 95% for visual inspection. (link)

Ramelteon is a melatonin 1 and 2 receptor agonist that is given as an 8mg dose at night and was found in one study to reduce the incidence of delirium from 30 to 10% in at risk, hospitalised elderly patients. (link)