MISCELLANEOUS Flashcards
Probability that a sick patient will have a positive test
Sensitivity
Probability that a healthy patient will have a negative test
Specificity
of true positives + false negatives divided by total number of tests done
Prevalence
True negatives divided by true negatives + false positives
specificity
Having a high false psoitive rate will lowera tests ability to be
specific
1 standard deviation =
68% of samples are around the mean
2 standard deviation =
95% of samples are around the mean
3 standard deviation =
99.7% of samples are around the mean
Positively skewed distribution (mean median mode order)
mean > median > mode
Negatively skewed distribution (mean median mode order)
mode > median > mean
TYpe 1 error
null hypothesis is rejected when it is actually true
Probability of a type 1 error
alpha. Often the p-value set to 0.05 (5% chance of a type 1 error)
Type 2 error
null is accepted when it is actually false. False negative
Beta
Probability of a type 2 error. 1-beta is the POWER often set to 80%
Compare numerical means of two different groups - use what test?
unaired t etest
example: average BMI in sleeve vs bypass pts
Compare two different numerical measurements taken from a single group of patients
paired t test
example: BMI in pts before vs after getting a sleeve
compare numerical means of three or more groups
ANOVA
average BMI in sleeve vs bypass versus gastric band pts
Compare categorical outcomes between two or more groups
Chi square test or Fischers exact test
example does VTE occur more often in pts who are obese?
Identify and adjust for multiple potential factors contributing a to a categorical outcome
multivariate logistic regression
example: in a large database, determine what variables contribute to incidence of infection
Identify and adjust for multiple potential factors contributing to a numerical outcome
multivariate linear regression
example in a large database, determine what variables contribute to total lengthj of stay
identify difference in survivorship over time betwen two or mrore groups
kaplan-meie analysis
example: cancer survival in pts who received neoadjuvamnt versus adjuvant chemotherapy
analyze a population at a particular moment in time to determine prevalence of factors and disease
cross sectional study
population of subjects are analyzed to associate certain factors with an outcome
cohort study
cohort study can determine what kind of risk
relative
case control study are always prospective or retrospective
retrospective
case-control study used to predict RR or OR
odds ratio!
absolute risk
overall probability of the outcome
relative risk
probability of outcome in exposed group compared to probability of outcome in non exposed group
odds ratio
odds of outcome in exposed group compared to odds of outcome in non exposed group
relative risk reduction
proportion of decreased risk due to not being exposed
1 - relative risk
Number needs to treat
1 / absolute risk reduction
What do predictive values take into account that sensitivtiy and specificity do not
prevalence
Sudden hypotension with pneumoperitoneum in other wise healthy person is due to
decreased CO
IVC is compressed which decreases venous return and therefore decreases CO
What happens to functional residual capacity with pneumoperitoneum
Decreases
What happens to ADH with pneumoperitoneum
Increases. An increase in IAP leads to catecholamine release and activation of RAAS with vasopressin release
What happens to SVR and CVP with pneumoperitoneum
Increased
What happens to pH due to pneumoperitoneum
decreased
What happens to MAP and PAP and mean airway pressure with pneumoperitoneum
Increase
What does CO2 sometimes do to myocardial contracility
Decrease
Bipolar can achieve sealant of vessels of what size
< or = 7 mm
Power of a study calculated as
1 - beta (beta represents chance of incorrectly accepting the null hypotehseis when it is not true)
difference between two unpaired treatments using ordinal variables
Mann Whitney U test
example: two groups of pts, one is receiving a new narcotic and the other is receiving normal narcotic. difference in pain levels
ordianl variable
ranking scales or visual analog scale, such as pain scale
nominal variable
named category such as a persons favorite color
Comparing two unpaired treatments using quantitaitive variables
unpaired t test
assumes normal distrubtion
compare >2 treatments using quantiative variables
ANOVA test
Gastric staple line for sleeve gastrectomy should start where
6 cm from the pylorusN
Non parametric vs parametric data
Expected distribution of population is normal (parametric) or skewed (non parametric)
Non parametric test assessing qualitative data
Chi squared
Non parametric test assessing unpaired ordinal ONLY
Mann-Whitney U
Non parametric test assessing paired nominal variables only
McNemar
Non parametric test assessing paired ordinal data
Wilcoxon signed-rank test
Mann-Whitney-U test is also called
Wilcoxon rank SUM test
Quantitative data can be ___ or ___
disecrete or continuous
What happens to GFR with pneumoperitoneum
Decreases
Persistent reflux following gastrectomy (but do not want to have roux en y conversion)
magnetic sphincter augmentation badm
Decreasing the mangnitude of difference between groups will do what to teh power of the study
Decrease
Decreasing the standard error the mean will do what to the power of a study
Increase it
Preload with pneumoperitoneum
Decreases
when the piecemea ltechnique is used to remove a polyp when should repeat cscope be
2-6 months to document complete removal and no regrowth of polyp
relationship of splenic artery to pancreas
superior
relationship of splenic vein to the pancreas
within or posterior
tx of acute PID
rocephin 250 mg IM x 1 + doxy 100 mg BID x 14 days
MC site of perforation during cscope
sigmoid colon
when is rigid proctoscopy useful
when asesssing exact location of low rectal tumors for preoperative planning
where is ureter in relation to broad ligament
medial leaf
what type of suture is used in hysterectomy
heavy absorbable suture such as chromic gut or polyglycolic acid
what are howell-jolly bodies
nuclear remnants of RBCs only present if entirety of spleen removed OR in sickle cell
what are pappenhemier bodies
iron granules seen in increased frequency after splenectomy
what are siderocytes
abnormal RBCs with cytoplasmic inclusions and iron granules not part of normal RBC. Seen in post splnectomy pt
what are Heinz bodies
aggregates of denatured hemoglobin seen when using special dye such as crystal violet
MC seen in pts with G6PD and thalassemias
what is basophilic stippling
blue granules dispersed throughout cytoplasm of RBC which represent ribosomal precipitates
ost often seen in thalassemies, alcohol abuse, lead and heavy metal poisoning
MC benign neoplasm of the spleen
hemangioma
prophylactic abx in kids after splenectomy
until 5 years old or 2 years after splenectomy
pen V potassium 125 mg BID
how often EGD for familial polyposis
every 1-2 years
how often for EGD with gastric ulcer
every 6 weeks until healed
how often EGD for low risk Barretts
every 2 years
how often EGD for high risk Barretts
every year
how often for high risk Barretts with low grade dysplasia
every 6 months
how often EGD for esoph varices following sclerotherapy and banding
every 6-8 weeks
grade Ib endometrial CA
> 50% myometrial involvement
ITP and platelets >30K and asymptomator or minor bleeding tx
observation
ITP with platelets <30K and asymptomatic or minor bleeding
corticosteroids
urgent management of pt with ITP and bleeding or prior to urgent procedure
IVIG
where is b12 absorbed
distal ileum
circulatory collapse - seen in spinal shock or neurogenic shock
neurogenic shock
bradycardia - seen in spinal shock or neurogenic shock
neurogenic shock
peripheral vasodilation - seen in spinal shock or neurogenic shock
neurogenic shock
is bulbocavernosus reflex present in spinal shock or neurogenic shock
spinal
neurogenic shock can occur after SC injuries down to what level
T6
elevated ICP can cause a palsy of whic hcranial nerve
6th
results in lateral rectus weakness and side by side diplopia
when is ICP monitoring required
GCS = or <8 who EITHER have any CT evidence of intracrnial pathology OR normal CT with 2-3 of the following: age > 40 any hx of hypotension abnormal motor posturing
Consider in pt with GCS of < or =12 who cannot be closely monitored or whose CT demonstrates evidence of intracrnial HTN
hydroceles occur more often on which side
right
Brown sequard syndrome
ipsilateral motor loss
contralateral pain/temp loss
central cord syndrome
UE»_space; severely than LE
anterior cord syndrome sx
Loss of motor, pain and temp below level of lesion but preserved proprioception ,vibration and pressure sensation
cause of hydrocele
patent processus vaginalis with peritoneal fluid
after orchiectomy reveals stage I seminoama the next step is to obtain
serum tumor markers. If elevated may need RP XRT and or chemo
disruption of upper ureter or UPJ is repaired by
debridement and primary n anastomosis
use interupted 5-0 or 6-0 absorbable sutures and place a double J ureteral stent or nephrostomy before completion of anastomosis
early symptoms of uncal herniation
compression of CN III –> anisocoria, ptosis, impaired EOM, sluggish pupillary light reflex on ipsilateral side of lesion
gerotas fascia anterior and posterior leaves remain open in what direction
inferiorly, allowing ureter and gonadal vessels to exit
course of right renal artery in relation to IVC
posterior