Seasons Greetings! Some delicacies from this month’s literature to add to your Christmas fayre:
Some have theorised that giving thrombolytics during cardiac arrest might result in survivors in those with a thrombotic aetiology, such as MI or PE. An RCT from 10 European countries on 1050 patients may have put that idea to rest: tenecteplase and placebo had the same survival outcomes when given to out-of-hospital arrest patients prior to transport to hospital, although a seven times greater incidence (2.7% vs 0.4%) of intracranial haemorrhage in the tenecteplase group.
Speaking of pulmonary embolism, a review of the disease reminds us that a meta-analysis of 5 RCTs of thrombolysis in patients with PE and arterial hypotension or shock reduces death or recurrent PE from 19% to 9.4% compared with heparin alone (NNT = 10). The benefit is less clear in those with evidence of RV dysfunction but who are normotensive; the need for further therapeutic interventions is reduced but mortality rates are unaffected. The risk of intracranial or fatal haemorrhage from thrombolysis in PE is 1.8%.
A review of hyperkalaemia and its treatment contains some useful pearls: calcium gluconate is preferred to calcium chloride because of the latter’s tendency to cause tissue necrosis if extravasation occurs; hypertonic saline may reverse the ECG changes of hyperkalaemia, particularly in the presence of hyponatraemia; 10mg nebulised salbutamol lowers serum potassium by about 0.6 mmol/l, whereas 20mg lowers it by about 1.0 mmol/l – however up to 40% of patients are resistant to the hypokalaemic effects of salbutamol, for unknown reasons; the effects of insulin/dextrose are additive to those of salbutamol; sodium bicarbonate does not reduce potassium in dialysis-dependent kidney failure. Read the full article for more detailed discussion
Cardiologists have described a new ECG sign of acute proximal left anterior descending coronary artery occlusion: instead of the signature ST segment elevation, the ST segment showed a 1-3 mm upsloping ST segment depression at the J-point in V1-V6 that continued into tall, positive, symmetrical T waves. In most patients there was also a 1-2 mm St elevation in AVR. These changes were seen in 30 of 1532 (2.0%) of anterior AMI patients. A recognition of this pattern is essential for ensuring these patients receive early reperfusion therapy.