Thursday December 17, 2009


Q: Lab call you with result that patient's pleural fluid has cholesterol level more than 45 mg/dL (1.16 mmol/L). What does it mean?


A; Pleural fluid is probably an exudate.

Using a cutoff point of 45 mg/dL for pleural cholesterol and/or LDH over 200 IU/L identified exudates with a sensitivity of 99% and a specificity of 98%.


Measurement of Pleural Fluid Cholesterol and Lactate Dehydrogenase - A Simple and Accurate Set of Indicators for Separating Exudates From Transudates - CHEST November 1995 vol. 108, no. 5 1260-1263

Wednesday December 16, 2009

Q: What is the mechanism of action of Mannitol in control of Intracranial Hypertension (Increase ICP)?


A; Immediately after bolus administration Mannitol expands circulating volume by help of osmotic forces, decreases blood viscosity, resulting in reflex vasoconstriction and lowering of intracranial pressure. Its osmotic properties take effect in 15-30 minutes when it sets up an osmotic gradient and draws water out of neurons.

Tuesday December 15, 2009

Q: Does Phenytoin (Dilantin) get cleared by hemodialysis or hemoperfusion?


A; No (clinically insignificant removal)

Clinical significance:

• In Phenytoin toxicity/overdose, Hemodialysis or hemoperfusion are ineffective for enhancing elimination.
• Hemodialysis patients do not require extra dosing post dialysis though require frequent monitoring due to lower albumin level.

Monday December 14, 2009
Abnormal sleep and errors more common in ICU nurses

Intensive care unit (ICU) nurses are more likely than floor nurses to have abnormal sleep and to experience a drop in vigilance during their shift that could impair patient safety, according to study findings presented at the CHEST 2009 meeting in San Diego, California.

"Nurses working in the ICU tend to have abnormal sleep and tend to have a greater frequency of errors across the length of their shift," lead researcher Dr. Salim R. Surani said. "These findings could be explained on the basis of the ICU nurses having a more impaired sleep quality as seen by PSQI (Pittsburg Sleep Quality Index), and perhaps having a more demanding and intensive work schedule in the ICU as compared to the floor."

Dr. Surani and colleagues from Baylor College of Medicine, Houston assessed ICU and floor nurses using the psychomotor vigilance test (PVT)

• ICU nurses made more errors at both the beginning and end of their shift than did floor nurses.
• As their shifts progressed, the ICU nurses made more errors (p = 0.029), while floor nurses showed no change.
• ICU nurses had significantly worse PSQI scores than did floor nurses (p = 0.041).
• Scores on the Epworth and Stanford sleepiness scales, however, were similar in the two groups.

Dr. Salim Surani is co-editor of this website and extensively published on 'sleep'.

Sunday December 13, 2009


Q: Describe relationship between Hypoxemia and acute Decompensated Right Ventricular Failure?

Answer: Oxygen is the most potent pulmonary vasodilator and liberal oxygen administration will reduce pulmonary vascular resistence and improve cardiac output.

Saturday December 12, 2009
The influence of white noise on sleep in subjects exposed to ICU noise

Background and purpose: There is disagreement in the literature about the importance of sleep disruption from intensive care unit (ICU) environmental noise. Previous reports have assumed that sleep disruption is produced by high-peak noise. This study aimed to determine whether peak noise or the change in noise level from baseline is more important in inducing sleep disruption. We hypothesized that white noise added to the environment would reduce arousals by reducing the magnitude of changing noise levels.

Patients and methods: Four subjects underwent polysomnography under three conditions: (1) baseline, (2) exposure to recorded ICU noise and (3) exposure to ICU noise and mixed-frequency white noise, while one additional subject completed the first two conditions. Baseline and peak noise levels were recorded for each arousal from sleep.

Results: A total of 1178 arousals were recorded during these studies. Compared to the baseline night (13.3±1.8arousals/h) the arousal index increased during the noise (48.4±7.6) but not the white noise/ICU noise night (15.7±4.5). The change in sound from baseline to peak, rather than the peak sound level, determined whether an arousal occurred and was the same for the ICU noise and white noise/ICU noise condition (17.7±0.4 versus 17.5±0.3DB, P=0.65).

Conclusions: Peak noise was not the main determinant of sleep disruption from ICU noise. Mixed frequency white noise increases arousal thresholds in normal individuals exposed to recorded ICU noise by reducing the difference between background noise and peak noise.


The influence of white noise on sleep in subjects exposed to ICU noise - Sleep Medicine, Volume 6, Issue 5, Pages 423-428 (September 2005)

Friday December 11, 2009

Q: What is the easy (and quick) way of knowing ideal body weight at bedside?

Answer: Ideal weight can be calculated as follows:

• Men = 106 lb for 5 feet in height plus 6 lb for each additional inch.
• Women = 100 lb for 5 feet in height plus 5 lb for each additional inch.
  
  
  Nutrition Management in the ICU - CHEST May 1999 vol. 115 no. suppl 2 145S-148S