Wednesday October 15, 2008
Cross Sulfa allergy - just a myth?

The clinical significance of cross-reactivity of medications in a person with a "sulfa" allergy continues to perplex clinicians and complicates decisions regarding patient safety. Historically, the term "sulfa" refers to a derivative of the antimicrobial agent sulfanilamide. More recently, the term has been applied to a diverse group of drugs, all of which contain the sulfonamide chemical structure (-SO2NH2).

OBJECTIVE: To provide a critical and comprehensive review of the literature, specifically case reports and observational studies used to support the concept of cross-reactivity between sulfonylarylamines and non-sulfonylarylamines.

DATA SOURCES: A list of medications was formulated from several different review articles. A MEDLINE/PubMed search was conducted (1966-March 2004) using the individual medications and the MeSH terms of drug hypersensitivity/etiology, sulfonamides/adverse effects, and/or cross-reaction.

STUDY SELECTION AND DATA EXTRACTION: A critical review of the methodology and conclusions for each article found in the search was conducted. The manufacturer's package insert (MPI) for each drug was examined for a statement concerning possible cross-reactivity in patients with a sulfonamide allergy. If indicated, the manufacturers were contacted to obtain any clinical data supporting the statement.

DATA SYNTHESIS: A total of 33 medications were identified. Seventeen (51.5%) of the MPIs contained statements of varying degrees concerning use in patients with a "sulfonamide" allergy; 21 case series, case reports, and other articles were found.

CONCLUSIONS: After a thorough critique of the literature, it appears that the dogma of sulfonylarylamine cross-reactivity with non-sulfonylarylamines is not supported by the data. While many of the case reports on the surface support the concept of cross-reactivity, on closer examination the level of evidence in many of the cases does not conclusively support either a connection or an association between the observed cause and effect.


Reference: click to get article

Sulfonamide Cross-Reactivity: Fact or Fiction? - Published Online, 11 January 2005, The Annals of Pharmacotherapy: Vol. 39, No. 2, pp. 290-301.

Tuesday October 14, 2008

Q: Which type of infrarenal abdominal aortic aneurysm (AAA) is more dangerous? (choose one)

A) Fusiform or B) Saccular

Answer: Saccular

Most (90%) infrarenal aneurysms are fusiform in appearance. It bulges or balloons out on all sides of the aorta.

A saccular aneurysm is balloon-shaped with a narrow neck, bulges out from the main arterial segment (bulges or balloons out only on one side) and is the most likely to rupture.

A pseudoaneurysm, or false aneurysm, is an enlargement of only the outer layer of the blood vessel wall. Sometimes, a tear can occur on the inside layer of the vessel resulting in blood filling in between the layers of the blood vessel wall, creating a pseudoaneurysm.

Monday October 13, 2008
Respiratory Failure Classification


Type I: Hypoxemic Failure (PaO2 < 60 at sea level)

Type II: Hypercapnic Failure (PCO2 > 45 mm hg)

Type III: Perioperative respiratory failure (increase atelectasis due to low functional residual capacity)

Type IV: Respiratory failure due to Shock. Type IV describes patients who are intubated and ventilated in the process of resuscitation for shock.

Sunday October 12, 2008
Silver-Coated Endotracheal Tubes decreases incidence of Ventilator-Associated Pneumonia?

Interesting study recently published in JAMA 1

Design, Setting, and Participants: Prospective, randomized, single-blind, controlled study from 54 centers in North America. A total of 2003 patients expected to require mechanical ventilation for 24 hours or longer were randomized.

Primary outcome measure: VAP incidence based on quantitative bronchoalveolar lavage fluid culture with 104 colony-forming units/mL or greater in patients intubated for 24 hours or longer.

Other outcomes measures: VAP incidence in all intubated patients, time to VAP onset, length of intubation and duration of intensive care unit and hospital stay, mortality, and adverse event.

Results

• Among patients intubated for 24 hours or longer, rates of microbiologically confirmed VAP were 4.8% (37/766 patients) in the group receiving the silver-coated tube and 7.5% (56/743) in the group receiving the uncoated tube, with a relative risk reduction of 35.9%
• The silver-coated endotracheal tube was associated with delayed occurrence of VAP
• No statistically significant between-group differences were observed in durations of intubation, intensive care unit stay, and hospital stay; mortality; and frequency and severity of adverse events

Conclusion: Patients receiving a silver-coated endotracheal tube had a statistically significant reduction in the incidence of VAP and delayed time to VAP occurrence compared with those receiving a similar, uncoated tube.



Reference: click to get abstract

Silver-Coated Endotracheal Tubes and Incidence of Ventilator-Associated Pneumonia, The NASCENT Randomized Trial , JAMA. 2008;300(7):805-813.

Saturday October 11, 2008

What is your Diagnosis?

Answer: Right bronchus intermedius intubation causing Right upper lobe atelectasis along with all of left lung collapse.

About 10% of ETT are initially placed in the right main stem bronchus. If tip is in bronchus intermedius, RUL will become atelectatic along with all of left lung.

Friday October 10, 2008

Q; What is Hemodialysis induced Vancomycin rebound phenomenon?

A; There is a rebound in vancomycin plasma concentrations at the end of the session. The plasma profile of vancomycin concentrations versus time indicates that concentrations decrease dramatically during the session and then increase when the session is stopped. This rebound may result from drug recirculation from plasma protein binding sites.

Clinical Significance: This rebound may be clinically significant, and it must be taken into account when determining vancomycin trough levels. It is recommended that determination of vancomycin trough levels in patients undergoing chronic haemodialysis should be performed before the haemodialysis session.

Reference: click to get abstract

Clinical review: Use of vancomycin in haemodialysis patients Crit Care. 2002; 6(4): 313–316

Thursday October 9, 2008
The feasibility of using ultrasound - for assessment of tracheal intubation / ruling out esophageal intubation