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

Wednesday October 8, 2008
Risk of death in ARDS - dead space fraction

Severity of hypoxemia, imaging and none of the single variable is predictive of risk of death in acute respiratory distress syndrome (ARDS) when measured early in the course of the disease. However the quintile of dead space fraction correlated well with later mortality in a few observational studies and in at least prospective study. The dead space fraction was independent risk factor for death.

dead-space fraction = (PaCO2 – PeCO2) ÷ PaCO2

PeCO2 is a mean expired carbon dioxide fraction and is measured with a bedside metabolic monitor. Metabolic monitoring (metabolic cart) is noninvasive and is used widely for metabolic and nutritional assessment.

Study Details

The dead-space fraction was prospectively measured in 179 intubated patients, a mean (±SD) of 10.9±7.4 hours after the ARDS had developed. Additional clinical and physiological variables were analyzed with the use of multiple logistic regression. The study outcome was mortality before hospital discharge.


Results

• The mean dead-space fraction was markedly elevated (0.58±0.09) early in the course of the ARDS and was higher among patients who died than among those who survived (0.63±0.10 vs. 0.54±0.09)
• The dead-space fraction was an independent risk factor for death: for every 0.05 increase, the odds of death increased by 45 percent
• The only other independent predictors of an increased risk of death were the Simplified Acute Physiology Score II, an indicator of the severity of illness and quasistatic respiratory compliance

Conclusions: Increased dead-space fraction is a feature of the early phase of the acute respiratory distress syndrome. Elevated values are associated with an increased risk of death



Pulmonary Dead-Space Fraction as a Risk Factor for Death in the Acute Respiratory Distress Syndrome - NEJM,Volume 346:1281-1286, Number 17, April 25, 2002

Tuesday October 7, 2008
Predicted body weights

The mantra of "low tidal volume" in ARDS is based on predicted body weight. This is a calculation based on age, gender and height.

Predicted body weight for men:

50 + (2.3 x [height in inches - 60])
or
50 + (0.91 x [height in centimeters - 152.4])

.

Predicted body weight for women:

45 + (2.3 x [height in inches - 60])
or
45 + (0.91 x [height in centimeters-152.4])

Reference: http://www.ardsnet.org/node/77460

Monday October 6, 2008
Do we have standardization of Intensive Care Units across the Globe

Wunsch and his colleague did the retrospective review of existing national administrative data. They identified sources of data in each country to provide information on acute care hospitals and beds, intensive care units and beds, intensive care admissions, and definitions of intensive care beds. Data were all referenced and from as close to 2005 as possible.

Setting: USA, France, UK, Canada, Belgium, Germany, Netherlands, and Spain.

Results: No standard definition existed for acute care hospital and ICU across countries.

Hospital bed varied in #: USA = 221/100,000, Germany = 593/100,000
Adults ICU bed: UK = 3.3/100,000, Germany = 24/100,000
ICU admissions: UK = 216/100,000, Germany = 2353/100,000

• Ratio of intensive care unit beds to hospital beds was highly correlated across all countries except the United States (r = .90)
• There was minimal correlation between the number of intensive care unit beds per capita and health care spending per capita (r = .45), but high inverse correlation between intensive care unit beds and hospital mortality for intensive care unit patients across countries (r = -.82)

Conclusion: Services vary drastically between countries with significant differences in both numbers of beds and volume of admissions. The number of intensive care unit beds per capita is not strongly correlated with overall health expenditure, but does correlate strongly with mortality.

Editor Comments: Need for standardization among ICU criteria would be a way to compare morbidity and mortality.



Reference: click to get abstract

Wunsch, H, Angus D, Harrison D, Collang O et al. Variation in critical care services across North America and Western Europe. Critical Care Medicine. 36(10):2787-e8, October 2008

Sunday October 5, 2008
Early percutaneous coronary intervention after fibrinolysis for acute ST elevation MI: Is there any role?

Bauer and his colleague evaluated the outcome of early percutaneous coronary intervention (PCI) after fibrinolysis in patients presenting with ST elevation MI. 2230 consecutive patients with STEMI treated with fibrinolysis were divided into two groups:

• patients treated with fibrinolysis only (n = 1540) or
• with additional PCI (n = 690) within a median of 150 min

Results:

• In-hospital mortality (9.3% versus 5.9%) and death/myocardial re-infarction (13.9% versus 9.7%) occurred significantly less often in the PCI group but after adjustment for the confounding factors in the propensity score analysis PCI did not significantly affect hospital mortality and death/myocardial re-infarction in the overall patient collective.
• Major bleeding complications were observed more often in the PCI group (7.3% versus 4.2%).
• In patients with a higher risk profile (TIMI risk score more than/=5) (n = 494) PCI was associated with a significant reduction of hospital mortality and death/myocardial re-infarction
  

Conclusions: In the overall patients' collective early PCI after fibrinolysis is not associated with an improved clinical outcome. However, in patients with a higher risk profile an early invasive strategy is associated with a risk reduction for mortality and the combined endpoint of death/myocardial re-infarction.

Reference: click to get abstract

Brauer T, Koeth O et al. Early percutaneous coronary intervention after fibrinolysis for acute ST elevation myocardial infarction: results of two German multi-center registries (ACOS and GOAL). Acute cardiac Care 2007; 9 (2): 97-103

Saturday October 4, 2008
Ultrafiltration in decompensated CHF

Loop diuretics, have been the therapeutic icon for decades, however it may be associated with increased morbidity and mortality because of deleterious effects on neurohormonal activation, electrolyte balance, and cardiac and renal function. Ultrafiltration, an alternative method of sodium and water removal, safely improves hemodynamic in heart failure patients as reconfirmed again in a recently announced study 1.

Findings: Among 200 decompensated CHF patients randomized to ultrafiltration or intravenous diuretics,

• 48 hours weight (P = 0.001) and net fluid loss (P = 0.001) were greater in the ultrafiltration group. Dyspnea scores were similar.
• At 90 days, the ultrafiltration group had fewer heart failure rehospitalizations/patient (P = 0.022) and patients presenting for unscheduled visits (21 vs. 44%; P = 0.009).
• No serum creatinine differences occurred between the groups.

Conclusion: In decompensated CHF, ultrafiltration causes greater fluid and weight loss, as well as have a fewer rehospitalization rate and unscheduled visit.


Related previous pearl: The ‘UNLOAD’ Study



Reference: click to get abstract

Costanzo, MR. Ultrafiltration in the management of heart failure. Current Opinion in Critical Care. 14(5):524-530, October 2008.