12. Illustration of Dogma
"The experiments of Harry Harlow and his associates at
the Primate Laboratory of the University ofWisconsin are
described in the textbook Principles of General
Psychology (1980 JohnWiley and Sons)”
18. The Reality
Monkeys trained to avoid manipulating an object .
Untrained animal placed in cage with a trained animal and
the object.
1 trained animal pulled untrained animal away from
object.
2 trained animals exhibited "threat facial expressions
while in a fear posture" when untrained animal
approached the object.
23. Dogma in Medicine
List of Dogma
Use of CVP to guide fluid resuscitation
Use of NGT aspirates to determine feed tolerance in ICU
Use of rapid sequence induction/cricoid pressure, esp in
children
Use of resonium in hyperkalemia acute management
Use of fluid boluses to treat oliguria
Use of IVC ultrasound to determine fluid status
Pulmonary edema management
Blah Blah Blah….
Long list if only you looked.
25. Scientometrics
The science of measuring and analyzing science.
Facts are not eternal.
In fact, Fact has a half-life.
26. So what is the half life of
facts in Medicine?
27. Half Life of Surgical Facts
260 abstracts
1935 to 1994
Estimated half-life of facts in surgical literature was 45
years.
28. Half Life of Medical Facts
Original articles and meta-analyses from 2 journals
(Lancet and Gastroenterology).
1945 to 1999
Cirrhosis or hepatitis in adults.
By 2000, 60% of 474 conclusions were still considered true,
19% obsolete, and 21% false.
29. Half Life of Medical Facts
Half-life of medical fact (in cirrhosis and hepatitis) was 45 years.
30. Half Life of Medical Facts
NEJM. 10 years (2001-2010). 2044 original articles: 1344
concerned a medical practice:
981 (73.0%) examined a new medical practice
363 (27.0%) tested an established practice.
146 (40.2%) reversed practice.
138 (38.0%) reaffirmed it.
79 (21.7%) inconclusive.
Half Life of Medical Facts may well be shortening.
36. GCS 8 and below
= no gag
= aspiration risk
= must intubate
True or False
37. AtThe Beginning
15 point scale.
E4V5M6
Original 14 point scale
revised in 1976 with the addition of a
sixth point in the motor response
Designed forTraumatic Head Injury
six hours after head trauma
38. Glasgow Coma Scale
American College of Surgeons Committee onTrauma
European Society of Intensive Care Medicine
Eastern Association for the Surgery ofTrauma
GCS <9 recommended threshold for intubation
39. Glasgow Coma Scale Problems
1 year, retrospective review. Blunt trauma patients with
presumed head injury with GCS less than or equal to 13
120 patients.
A significant number of patients with a GCS of less than or equal
to 9 required emergent intubation.
A significant minority of patients with a GCS score of 10-13
required emergent intubation (20%) or had intracranial
pathology on head CT scan (23%).
40. Glasgow Coma Scale Problems
Problem with the Score
120 mathematical combinations!
18 possible permutations exist for GCS 9
17 for scores 8 and 10
14 for scores 7 and 11
10 for scores 6 and 12
Therefore, not all GCS 9 are equal.
43. Glasgow Coma Scale Problems
Problem with the Score
E
Spontaneous (4) : indicative of activity of brainstem arousal
mechanisms but not necessarily of attentiveness
Vegetative States: Eyes may spontaneously open. “Lights on, but
nobody at home”.
Noxious stimulus: grimace and eye closure.Then how?
Eye injury.
Drugs: muscle relaxants, sedation.
44. Glasgow Coma Scale Problems
Problem with the Score
V
Facial injury.
Focal neurological injury:
Broca’s aphasia
Wernicke’s aphasia
Conductive aphasia
Language.
Intubation, tracheostomy.
Drugs: muscle relaxants, sedation.
45. Glasgow Coma Scale Problems
Problem with the Score
M
Motor skew
No correlation to severity:
M3: internal capsule or cerebral hemispheres injury
M2: midbrain to upper pontine damage
46. Glasgow Coma Scale Problems
> 90% publications use 14-item GCS.
Timing of the initial GCS assessment inconstant.
GCS components seldom utilized: loss of information.
Confounders often not reported and, if they are, not in a
standardized manner.
“current inconsistent and inappropriate use of GCS
diminishes its reliability in both a clinical and a scientific
context.”
47. Glasgow Coma Scale Problems
French. 60 subjects.
Observer bias.
Errors up to 2 points.
49. Glasgow Coma Scale Problems
Designed forTraumatic Head Injury
six hours after the occurrence of head trauma
Cannot be used for other pathological states.
73 patients.Drug or alcohol intoxication. GCS 3 to 14.
No patient with a GCS <9 aspirated or required intubation.
1 patient required intubation; this patient had a GCS of 12
on admission to the ward.
50. GCS is a reliable predictor
of outcomes.
False
Not precise.
Many limitations.
51. GCS is applicable in all ICU
patients.
False
Designed for trauma.
May not be applicable to poisoning, medical diseases.
52. GCS <9
= no gag
= aspiration risk
= must intubate
False
Not all need intubation.
53. Summary
Many limitations.
GCS for head injury. Be careful about extrapolating to
other conditions.
Not reliable prognostic factor.
Not all GCS < 9 require intubation.
56. Indications for CVC
Hemodynamic monitoring including central venous
pressure (CVP), central venous oxygen saturation (SCvO2)
or for insertion of a pulmonary arterial catheter.
For infusion of irritants (eg. vasopressors,TPN,
chemotherapy)
Transvenous cardiac pacing
Plasmapheresis, apheresis, hemodialysis or CRRT
Poor peripheral venous access
57. CVP can be used to
monitor hemodynamics
True or False
62. CVP
Review/case series of 14 different cases, including a
neonate.
Descriptive: benefit using CVP for additional information.
63. CVP Myth Buster
Simultaneous measurement of CVP and PCW in patients
with AMI, during volume expansion or diuresis.
CVP:
no consistent relation to PCW.
Did not predict changes in PCW during fluid therapy.
3 patients with pulmonary edema had normal CVP.
“CVP in AMI at best of limited value, and at worst seriously
misleading”.
64. CVP Myth Buster
500 ml of 5 % albumin. 1 hour. 22 patients with CVP
greater than 15 cm. H2O.
CVP decreased in 14 (64 percent).
CVP increased slightly but not significantly in 8 (36
percent).
“High initial CVP is not a reliable index of either
hypervolemia or cardiac failure in critically ill patients”.
71. CVP Myth Buster
24 studies. Pooled correlation coefficient between
CVP and measured blood volume
0.16 (95% CI, 0.03 to 0.28)
Baseline CVP and change in stroke index/cardiac index
0.18 (95% CI, 0.08 to 0.28).
Delta CVP and change in stroke index/cardiac index
0.11 (95% CI, 0.015 to 0.21).
Baseline CVP was 8.7+/-2.32 mm Hg in the responders
compared to 9.7+/-2.2 mm Hg in nonresponders.
72. Stats
What is a Receiver Operating Characteristic Curve (ROC)?
73. Receiver Operating Characteristic
Curve (ROC)
True positive rate (Sensitivity) plotted against false
positive rate (100-Specificity) for different cut-off points.
74. Receiver Operating Characteristic
Curve (ROC)
Test with perfect discrimination: ROC curve passes
through the upper left corner (100% sensitivity, 100%
specificity).
Therefore the closer the ROC curve is to the upper left
corner
The higher the AUC of ROC curve = higher overall accuracy
of test.
75. CVP Myth Buster
The pooled area under the ROC curve was 0.56 (95% CI,
0.51 to 0.61).
76. Tale of 7 Mares
7 Horses. Standing position in “standing dock”
Bled for 1 hours at 16 mL/kg/h.
Central venous pressure (CVP), central venous blood gas,
blood lactate concentration, and heart rate measured.
Only study to show reliable correlation.
77. Half Life of Medical Fact
49 years
46 years
Not too far off!
78. CVP Myth Buster
43 studies
AUC 0.56 (95% CI, 0.54-0.58) with no heterogenicity
between studies.
0.56 (95% CI, 0.52-0.60) for studies done in ICU.
0.56 (95% CI, 0.54-0.58) for studies in OT.
79. CVP can be used to
monitor hemodynamics
False
No, it cannot and should not.
90. Resonium
Approved by FDA in 1958.
4 years before drug manufacturers were required to prove
the effectiveness and safety.
Quoted studies of efficacy:
91. Resonium Myth Buster
8 patients: 5 given resonium, 3 given sorbitol (laxative)
0 K+ diet: High sugar syrup only.
K+ checked on Day 5.
Resonium 6.6 -> 5.2
Sorbitol 6.3 -> 4.6
92. Resonium Myth Buster
Uncontrolled study. 32 patients. Acute and chronic renal
failure.
23 of 30 cases: K+ fell by at least 0.4 mmol/L in the first 24
hours.
Low K+ diet.
20% Dextrose IV. Insulin. NaHCO3.
No statistical analysis.
95. Resonium – Does it work?
1 mmol K+ binds 1 g of resin.
In vivo, sodium only partially released: efficiency is 33%.
Bind any cation: Calcium, hydrogen, Magnesium
10 mmol of K+ bound and excreted per 30-g dose.
What doses have you seen prescribed in your hospital?
How much K+ would that clear?
96. Resonium – why it seems to
work?
Given with laxatives/sorbitol – poop works.
Sodium exchanged: possibly absorbed: plasma expansion
= dilution!
Other things you did worked.
Low K+ diet
Insulin-Detrose
Dialysis
Spurious in the first place?
97. Resonium Myth Buster
Increase insoluble K+ output but decrease soluble K+
output: no significant effect on total K+ output.
Did not decrease serum K+ at 4, 8 and 12 hr.
Single-dose resin-cathartic therapy produces no or only
trivial reductions in K+.
98. Resonium Myth Buster
FDA warning:
Severe constipation.
Colonic necrosis.
Wisdom of using Resonium challenged.
99. Resonium is a resin which
binds potassium and aids
excretion.
False
112. Left LateralTilt averts fetal harm?
20 term parturients
Neither the left or the right pelvic-tilt position associated
with a significant change in leg blood flow or maternal
heart rate compared to the supine position.
Fetal heart rate and umbilical Doppler resistance did not
change in any position.
113. Left LateralTilt averts fetal harm?
25 term parturients.
Supine and in both right and left 5 degrees and 10 degrees
lateral tilt positions.
No significant difference among fetal variables in the
various maternal position.
114. Left LateralTilt averts fetal harm?
25 term parturients.
4 positions (random order): supine with a 15-degree left
tilt, sitting, and left lateral and right lateral positions.
No significant differences in fetal heart rate, pulsatility
index, or resistivity index among positions.
116. Maternal Harm?
157 term parturients. Suprasternal doppler. NIBP of upper
and lower limbs
11 patients CO decreased >20%, without changes in SBP,
when tilted to <15°: attributable to IVC compression.
Only 1 patient in the supine had aortic compression with
the SBP in the upper limb 25 mm Hg higher than the lower
limb
117. Maternal Harm?
573 pregnant subjects undergoing antepartum Non-Stress
Test.
Only 2% had presyncopal symptoms when supine
(did not affect the NST, either in terms of reactivity or any
pathological findings)
119. Angle Matters
157 term parturients. Random position : 0°, 7.5°, 15°, and
full left lateral tilt.
CO 5% higher when patients were tilted at ≥15° compared
with <15°.
120. Angle Matters
16 anaesthetists. Almost all less than 15 degree tilit
Visually guess was grossly inaccurate in 42 of 43 patients.
Average tilt given was only 8.09 degrees
122. How to get the tilt matters
51 term parturients
Random left lateral, supine-to-tilt and left lateral-to-tilt
positions using a Crawford wedge.
Femoral vein area, femoral vein velocity, femoral artery area,
pulsatility index, resistance index and right arm MAP and HR.
Moving from the full left lateral to the lateral tilt position may
prevent aortocaval more than when from a supine to left lateral
tilt position.
123. The gravid uterus causes
IVC and aortic
compression.
True
But not all symptomatic.
124. IVC compression and the
fetus is harmed.
Maybe.
Current evidence suggest not.
125. Left lateral tilt is a
solution.
True
But correct angle needed.
Full left lateral is better if you need it.
126. Summary
~1-4% of term parturient affected.
Majority not symptomatic.
Fetal compromise might be over-emphasized.
Visual estimated (agar agar) token tilt is pointless.
Tilt often overestimated visually.
Want to do it, then do it properly: full lateral (then possibly
tilt back).
132. Loop Diuretic/Frusemide
54 critically ill surgical patients.
Frusemide increased urine output, COsm, and CNa.
Produced no change in GFR, RPF, RBF, and RBF
distribution.
133. Loop Diuretic/Frusemide
In-hospital mortality RR 1.11 (95% CI 0.92 to 1.33)
Renal replacement therapy RR 0.99 (95% CI 0.80 to 1.22),
Possibly increased risk of temporary deafness and tinnitus
with high doses RR 3.97 (95% CI 1.00 to 15.78).
139. Fluid Bolus
Reality:
No consistent renal histopathological changes in human or
experimental septic AKI.
Majority of studies reported normal histology or only mild,
nonspecific changes.
ATN was relatively uncommon.
143. Excessive Fluid
Less fluid, better oxygenation.
Although no difference in mortality.
Less fluid, but no increase risk in dialysis rates.
Infer: fluid does not affect dialysis rate.
144. Excessive Fluid
10 ICU. Italy.
601 patients: 132 had AKI. Mortality 50% in this group.
Non-survivors had higher mean fluid balance (1.31 ± 1.24
versus 0.17 ± 0.72 L/day; P <0.001) compared to survivors.
146. AKI/Oliguria can be
treated with fluid boluses.
False
And it might even be harmful.
Avoid “therapeutic drowning”
147. Summary
In the treatment of oliguria/AKI in ICU:
Diuretic: no acute role.
Fluid bolus: no role unless acute hypovolemia/hemorrhage.
Increase blood pressure: yes, if baseline BP is high.
Dialysis: trend to mortality benefit if started early.
Doing nothing is not unreasonable.