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.

Friday October 3, 2008


Case: 58 year male brought to ER with high fever along with mental status change. In ER patient had a witnessed seizure. Urine output is marginal. You received following lab values

Hb 7 gm/dl, Platelets: 14 /μL, Cr.: 2.6 mg/dl

Your next line of action along with treating rescuing airway and treating seizure is: (choose one)

A) Initiate Sepsis protocol
B) Perform Lumbar punture (to rule out meningitis)
C) Transfue platelets
D) Call for plasmapheresis
E) Initiate Dialysis



Answer: D

This patient most probably has thrombotic thrombocytopenic purpura (TTP). It has 5 basic criteria

• thrombocytopenia,
• Microangiopathic hemolytic anemia,
• CNS dysfunction,
• fever, and
• renal failure

The therapeutic effects of plasmapheresis in the critically ill patient with TTP are often dramatic: Severe neurologic manifestations may disappear, and laboratory abnormalities may diminish in a few hours. Platelet transfusions should be avoided because they have been accompanied by marked deterioration in either renal or neurologic status. The treatment of seizures in TTP is the same as for seizures with other complicated hematologic disorders.

Splenectomy is a reasonable treatment option for TTP patients refractory to standard TPE or who have experienced multiple and/or complicated relapses 2.


Review at emedicine.com: Thrombotic thrombocytopenic purpura (TTP)



Reference: Click to get abstrat

1. Thrombotic thrombocytopenic purpura: Treatment with plasmapheresis - American Journal of Hematology, Vol. 24 issue 4, Pages 329 - 339, Published Online: 11 Jul 2006

2. Role of splenectomy in patients with refractory or relapsed thrombotic thrombocytopenic purpura. Aqui NA, Stein SH, Konkle B, Abrams CS, Strobl FJ. Journal of Clinical Apheresis 2003;18:51-54.

Thursday October 2, 2008


Case: You inserted central line. While you were on your way to check CXR to confirm line placement, nurse request you to check KUB also to confirm enteral feeding tube placement (DHT). Interestingly, KUB shot this morning had IVC filter which is no more present there?

Answer: Guide wire during central line procedure probably travelled into inferior vena cava and dislodged IVC filter !!

Related previous pearls:

Guide wire length
Peres Nomogram

References: click to get abstract / article

1. Guidewire Dislodgment of Inferior Vena Cava Filters During Insertion of Central Venous Catheters, Vascular and Endovascular Surgery, Vol. 31, No. 5, 587-593 (1997)

2. Direct measurement of the distance from subclavian and internal jugular vein access sites to the superior vena cava-atrial junction during central venous catheter placement. Crit Care Med 2000; 28: 138–42

3. Greenfield Inferior Vena Cava Filter Dislodged During Central Venous Catheter placement, Chest 1994;106;957-959