Evidence Based Medicine
1) Question: I have a patient with AMS and fever and have found a source. Do I need to do a lumbar puncture?
The short answer is that in elderly patients presenting with fever and altered mental status, finding a source of infection does not negate the need to do the LP. In fact, those with an obvious source (lung, urine, skin, etc) are more likely to have meningitis than those without an obvious source. Read the paper for more info.
What about younger patients? Well, it's not quite as clear but most data supports still doing the LP.
2) Question: I have a sick patient with pneumonia. He's gotten antibiotics, oxygen, basic labs, and is ready to be admitted. Oops! I forgot the blood cultures!??! Is this going to mess up his treatment?
Do Emergency Department Blood Cultures Change Practice in Patients with Pneumonia?
The short answer is that blood cultures rarely change treatment but can cost thousands of dollars. Read the paper for more info.
Another question: So why do we get them routinely on admitted pneumonia patients?