Miscellaneous Flashcards
transfusion related lung injury
Transfusion related lung injury is most common following the transfusion of plasma components such as platelets and FFP. The condition is due to leucocyte antibodies in the transfused plasma. This causes leucocyte sequestration and degranulation in the lung. This produces marked microvascular and tissue damage with the development of a non cardiogenic pulmonary oedema. Because the primary problem is one of tissue injury, diuretic therapy is largely unhelpful.
anaesthetic agentsis most likely to induce adrenal suppression
Etomidate is a recognised cause of adrenal suppression, this has been associated with increased mortality when used as a sedation agent in the critically ill.
power calculation
The components that are nearly always needed for power calculations are :
Size of effect
Significance level
Sample size used to detect the effect
Desired power value
Type 1 Error
A test rejects a true null hypothesis. Analogous to false positive. It usually equates to the significance level assigned to a test.
Related to the p value
Type 2 Error
A test fails to reject a false null hypothesis. It is related to the power of a test.
Statistical power
The power of a test is the probability that the test will reject the null hypothesis when it is false (thereby avoiding a type 2 error). Increasing the power of a test will reduce the probability of a type 2 error. Usually a value of 0.8 is selected.
ASA grading
1 No organic physiological, biochemical or psychiatric disturbance. The surgical pathology is localised and has not invoked systemic disturbance.
2 Mild or moderate systemic disruption caused either by the surgical disease process or though underlying pre-existing disease
3 Severe systemic disruption caused either by the surgical pathology or pre-existing disease
4 Patient has severe systemic disease that is a constant threat to life
5 A patient who is moribund and will not survive without surge
Anal SCC virus
Infection with human papilloma virus 16 is a risk factor for the development of intra epithelial dysplasia of the anal skin with subsequent increased risk of invasive malignancy.
Nominal
Numbers are assigned to data that has no underling numerical value (e.g. marital status)
Ordinal
Has numbers that can be assigned to a natural underlying order (e.g. tumour grades)
Discrete
Data has a discrete numerical value, that has to be a whole number (e.g. number of deaths)
Continuous
Data has a numerical value that may not be a whole number and often reflects a direct measurement (e.g. weight)
Normal distribution
if the mean, median and mode overlap numerically then the data will be normally distributed
Parametric vs Non parametric
Parametric methods of data analysis assume that the underlying data set has a normal distribution. Non parametric methods do not make assumptions about the nature of the underlying data.
Parametric tests
T test
Paired T test
Non parametric tests
Mann Whitney U
Chi squared
Spearman’s Rank Correlation
Wilcoxon Signed Rank test
T test
Direct comparison of data sets which are normally distributed
Mann Whitney U
Ranked method for non parametric data