Thursday, January 31, 2013

Hypersensitivity pneumonitis review

From the blue journal.

HP can present in many forms. Think of it in any patient presenting with interstitial lung disease.

Wednesday, January 30, 2013

Cognitive changes after survival of critical illness

This is now a well known entity. It was recently reviewed here in CCJM. Strategies for prevention remain controversial. Much attention has been devoted to sedation during mechanical ventilation in terms of dose, duration and choice of agent. And while these factors may impact the development of delirium it is not clear whether they affect the development of impaired cognition weeks and months after recovery. Regarding the choice of ventilator sedation agent the authors opine:

In our practice, we use dexmedetomidine as our first-line sedation therapy. In patients with hemodynamic instability, we use benzodiazepines. We reserve propofol for very short periods of intubation or for hemodynamically stable patients who cannot be sedated with dexmedetomidine.

Tuesday, January 29, 2013

Althma: part of the pro-inflammatory syndrome of obesity?

From the blue journal:

Objectives: We hypothesized that leptin levels would be increased in the bronchoalveolar lavage fluid from overweight/obese subjects and, furthermore, that leptin would alter the response of alveolar macrophages to bacterial LPS...
Measurements and Main Results: Leptin levels were increased in overweight/obese subjects, regardless of asthma status (P = 0.013), but were significantly higher in overweight/obese subjects with asthma. Observed levels of tumor necrosis factor-α were highest in overweight/obese subjects with asthma. Ex vivo studies of primary alveolar macrophages indicated that the response to LPS was most robust in alveolar macrophages from overweight/obese subjects with asthma and that preexposure to high-dose leptin enhanced the proinflammatory response. Leptin alone was sufficient to induce production of proinflammatory cytokines from macrophages derived from overweight/obese subjects with asthma.
Conclusions: Ex vivo studies indicate that alveolar macrophages derived from overweight/obese subjects with asthma are uniquely sensitive to leptin. This macrophage phenotype, in the context of higher levels of soluble leptin, may contribute to the pathogenesis of airway disease associated with obesity.

Monday, January 28, 2013

When your patient on pradaxa bleeds

---or has to have an invasive procedure: here is an update from Circulation.

Key topics...

Coag tests:
The aPTT is not very quantitative but can determine the presence or absence of drug effect. A normal value indicates absence of effect; a value greater than 2.5 x control 8-12 hours post dose indicates excess. The TT is also discussed in the article but is not in everyday clinical use.

Procedures:
Pradaxa need not be stopped for dental work, skin biopsy or cataract extraction but such procedures should ideally take place greater than 10 hours post dose.

For more invasive procedures it's a little more complicated:

For procedures associated with a moderate risk of bleeding, dabigatran should be held for 2 to 3 half-lives, whereas it should be held for 4 to 5 half-lives before procedures associated with a high risk of bleeding. Examples of procedures with a moderate risk of bleeding include pacemaker or implantable cardioverter-defibrillator implantation and colonoscopic resection of polyps, particularly those that are sessile and have a broad base. Procedures associated with a high risk of bleeding include urologic procedures, such as transurethral prostate resection, major abdominal or pelvic surgery for cancer, joint replacement surgery, cardiac surgery, and neurosurgery.

Here is an algorithm.

Also this:

If urgent surgery or intervention is required, the risk of bleeding must be weighed against the clinical need for the procedure. Ideally, surgery should be delayed for at least 1 half-life after the last dose of dabigatran or until the aPTT is normal or near normal. If the procedure is performed 2 to 4 hours after the last dose of dabigatran, the risk of bleeding is increased and strategies to reduce bleeding may be required.

Post procedure it can be restarted as soon as hemostasis is secured and bleeding risk is believed to be low, keeping in mind that unlike the case with warfarin the resumption of anticoagulant effect will be almost immediate.

The bleeding patient:
There is NO antidote although a neutralizing antibody is being developed (analogous to digibind?).

So you stop the drug, calculate the patient's creatinine clearance and, knowing that it has first order elimination kinetics you can do the math. For more severe, life threatening bleeding (e.g. head bleeds) that is not enough. It is removed pretty well by hemodialysis. Although there is no specific antidote currently available there has been talk of using 4 factor PCC (not available in the US), 3 factor PCC supplemented with a little recombinant activated factor VII or factor VIII inhibitor bypassing activity. Those remedies are mentioned in the review. The evidence to support their use is slim but an algorithm is presented.

The full text of the review is available at the link above.

Sunday, January 27, 2013

Hereditary colon cancer syndromes

This review from CCJM covers clinical features including extracolonic tumors, classification, genetics, recognition and management.

Saturday, January 26, 2013

Update on hypertrophic cardiomyopathy

Scientific advances in HCM have added much needed clarity to our understanding of the disease and its treatment approach. Here's an update in Circulation. Free full text.

Wednesday, January 16, 2013

Should we artificially lower temperature in septic patients? It's complicated.

In general the lowering of body temperature in febrile patients via antipyretics or external methods is useless in terms of outcomes and may be harmful. Exceptions include heat stroke and other hyperthermia syndromes, stroke patients and post cardiac arrest patients.

The issue recently became more nuanced when publication of this paper from the blue journal added another possible exception: patients in septic shock treated with external cooling, in whom a decrease in pressor requirements and mortality was observed. On the other hand the use of antipyretics in septic patients across the board was associated with increased mortality in this study.

It is intuitive that external cooling would reduce pressor requirement because it induces vasoconstriction.

Tuesday, January 15, 2013

Thursday, January 10, 2013

Peripartum cardiomyopathy

This topic was nicely reviewed in the Texas Heart Institute Journal and the free full text can be accessed here.

Key points:

Its onset can be in late pregnancy or up to 5 months postpartum.

Diagnosis is by exclusion of other heart disease combined with, in order to avoid overdiagnosis, very specific echocardiographic criteria.

Treatment includes general heart failure therapy (a table in the article summarizes drug precautions during pregnancy and lactation) and disease specific therapies.

Recovery is frequent but not invariable.

Wednesday, January 09, 2013

Neurogenic pulmonary edema

Some lessons in neuropulmonology from the journal Critical Care:

A common thread among all case descriptions of NPE is the severity and acuity of the precipitating CNS event. Neurologic conditions that cause abrupt, rapid, and extreme elevation in intracranial pressure (ICP) appear to be at greatest risk of being associated with NPE..

The autonomic nervous system and catecholamines play a significant role.

Tuesday, January 08, 2013

Annoying habits in the medical record

Here are some of Dr. Herb Fred's pet peeves. A couple of my favorites:

Many consultants from various disciplines routinely end their reports with, “Thank you for allowing me to participate in the care of this most interesting patient.” What is the difference between an uninteresting patient, an interesting patient, and a most interesting patient?7 The answer, like beauty, lies in the eyes of the beholder. In my eyes, all patients are interesting, but not all doctors are interested.8 A simple “Thank you” or “Thank you for this consultation” would be sufficient and devoid of insincerity and cliché.

Finally, “The patient is ‘satting’ at 88%.” This expression of the patient's oxygen saturation level crops up frequently, not only in hospital records, but also in Morning Report, teaching rounds, and doctors' lounges. Patients can sit or be sitting, but they can't sat or be satting. To sat is not a verb form. It's a neologism—arguably the most popular neologism in medicine today. House officers are particularly fond of it, uniformly include it in case presentations, and consider it the 5th vital sign.9 Unless teaching faculties consistently prohibit its use by all trainees, “satting” will continue to saturate the medical environment.

I would add that those fond of the term “satting” are not only grammatically incorrect but also tend to be confused about the physiology of oxygen transport.

Dr. Fred opens:

This editorial focuses on selected examples of bad habits that I have found repeatedly in traditional (paper) hospital records.

Well, Dr. Fred, it only gets worse in the electronic medical record.

Monday, January 07, 2013

The EMR and diabetes care: no impact

This study is important because it looked not just at the phony surrogate of performance but also at outcomes. The EMR was no better than paper in either category. HT to Clinical Cases and Images.

Friday, January 04, 2013

Dr. Smith talks about his ECG blog

With the passage of the old generation of electrocardiography masters (Marriott, Hurst) a new generation of ECG masters is arising and it comes from the ranks of emergency medicine. The driving force behind this is the fact that early “STEMI” recognition, both in the ED and in “the field,” is a performance measure. No one wants to miss one and no one wants egg on their face for calling a STEMI false alarm. Emergency medicine types are motivated more than ever to get it right.

Dr. Smith teaches residents in emergency medicine. His blog is on my list of the best ECG resources on the web.

Thursday, January 03, 2013

Doctors on the receiving end of abuse

Sometimes it's patient against doctor, sometimes it's doctor against doctor. This paper is not quantitative but it has a ring of truth.

Wednesday, January 02, 2013

Cardiac device associated infections

Here's a nice little article in the Texas Heart Institute Journal.

Key points:

Presenting findings may be nonspecific and subtle. It may show up late after implantation. System explantation is generally recommended.