Book 1 Flashcards
And a little bit of book 2
What cells produced TNF alpha?
M1 macrophages
Anti-TNF monoclonal antibodies and recumbent, soluble receptors help with what diseases in humans
Crohn’s disease and rheumatoid arthritis
Where do white blood cells marginate?
Post capillary venules and pulmonary capillaries
What pro inflammatory cytokines do M1 macrophages produce?
IL-1B, IL-6, TNF-a
What are the neutrophil granules and what do they produce?
Primary/azurophils: myeloperoxidase, defensins, lysosome hydrolases, proteases
Secondary: MMPs
Tertiary/gelatinase: preformed receptors
IL-1a, IL-1b, IL-6, TNF-a
What is the precursor prostaglandin?
PGH-2
The intracellular fluid compartment is what fraction of total body water and what percent of weight?
2/3 total body water
40% of weight
The extracellular fluid compartment is what fraction of total body water, and what percent of weight? What are the two sub compartments and their percentages?
ECF is 1/3 total body water, 20% body weight
Plasma/IVF: 25%
Interstitial fluid: 75%
How long does it take for isotonic crystalloids to equilibrate, and how much is left in the intravascular space?
20-30 or 30-60 min
Only 25% remains in IV space
What is two times maintenance for IVF?
4-8 mL/kg/hr
What are side effects of hypertonic saline?
Phlebitis and hemolysis
Hypertonic saline is useful for what conditions
Head trauma or cardiovascular shock in patients more than 30 kg that need a large amount of IV fluids, but don’t have much time
How long does IV volume expansion last after hypertonic saline?
Less than 30 minutes
What are side effects of synthetic colloids?
They decrease factor 8 and vWF, impair platelet function, and decrease stability of fibrin clots by increasing fibrinolysis
What are risks of 25% human albumin?
Potentially fatal, acute or delayed hypersensitivity reactions, volume overload, coagulopathy
Patient will have an increase in IgG against human albumin, so no repeat dosing
What is the rate of treatment of chronic hypernatremia?
</= 0.5 mEq/kg/hr
What is the calculation for free water deficit?
0.6 x weight x ((Na patient / Na normal) -1)
What does a negative base excess mean?
Non-respiratory acidosis
What is the equation for anion gap?
(Na + K) - (Cl + HCO3)
Most blood gas analyzers report a value for base excess that…
Can only be used to assess the metabolic component of acid/base disturbances and is the difference between normal buffer base and the patient buffer base
How do you calculate the amount of bicarbonate needed?
0.3 x body weight x base deficit
What are the four types of shock?
Hypovolemic, cardiogenic, distributive, hypoxic
What is the equation for oxygen delivery?
DO2 = CO x CaO2
What is the equation for arterial oxygen content (CaO2)?
CaO2 = (1.34 x Hgb x SaO2) + (0.003 x PaO2)
What is the equation for oxygen uptake? VO2
VO2 = CO x (CaO2 - CvO2)
What is the oxygen extraction ratio equation?
O2ER = (VO2 / DO2) x 100
How can lactate increase even with normal perfusion
Type B lactic acidosis: impaired mitochondrial function due to sepsis, diabetes, neoplasia, drug/toxins
Type A is due to inadequate DO2
What is CVP and what is it a surrogate for? What is normal?
CVP is hydrostatic pressure, but is a surrogate for preload
Normal is 0-5 cmH2O
What is the lifespan of a platelet?
6 to 8 days
What is the method of action of antithrombin
Binds and inactivates thrombin (f2) and f10a
Neutralizes Kalinin, f7, f9, f11, and f12
Rate of neutralization increases when antithrombin binds heparin
What is a normal BMBT and what does it test?
Dogs < 3 min, cats 34 - 105 sec
Primary hemostasis
How does a vitamin K deficiency impact PT and aPTT
Prolongs PT because of short half-life of f7 (4 to 6 hrs)
Prolongation does not occur until a factor is less than 25 to 30% of normal
What is the best test for detecting hypercoagulability?
Thromboelastography (TEG)
Anemia: hypercoagulable
Polycythemia: hypocoagulable
How does desmopressin (DDAVP) work?
Binds V2 receptors and induces release of subendothelial vWF stores
For type I vWD
Works in 30 min, lasts 4 hrs
M1 vs M2 macrophages: which is pro-inflammatory and what does it secrete?
M1 are pro-inflammatory, secrete IL-1B, IL-6, and TNF-a
What are the primary functions of TNF-a?
Initiates production of pro-inflammatory cytokines, ROS, and chemotaxins
Has anti-tumor activity
What are the pro-inflammatory cytokines?
TNF-a, IL-1B, IL-6, IL-8
(alpha-beta-68)
What are the anti-inflammatory cytokines
IL-10, IL-1ra
What is the parent prostaglandin?
PGH2
Which COX enzyme is constitutively expressed?
COX-1
What induces expression of COX-2?
trauma, growth factors, pro-inflammatory cytokines
What are the functions of TXA-2 and what cells secrete it?
vasoconstriction and platelet aggregation
secreted by platelets and macrophages
What is the action of nitric oxide (NO) and how does it exert this effect? Is it pro- or anti-inflammatory?
Vasodilation - has direct effect by diffusion into smooth muscle
BOTH pro and anti-inflammatory
Acute phase proteins change by what % during inflammation? What is the major negative APP?
change by 25%
ALBUMIN is the major NAPP
What are the deoxyribonucleotide pairs in DNA?
Purines to pyrimidines:
Adenine to thymine
Cytosine to guanine
What are exons and introns in DNA?
Exon = coding DNA
Intron = non-coding DNA
What are the 4 types of stem cells?
embryonic
adult
fetal/perinatal
induced-pluripotent
What are the 3 types of stem cell potentcy?
Totipotent: cells from all layers, including fetal membranes
Pluripotent: cells from 1+ germ layer but not fetal membranes
Multipotent: limited to germ layer they originated from (hematopoietic, mesenchymal, neural)
What anti-inflammatory agents are produced by MSCs?
TSG6, IL-1ra, PGE2
(Study guide also says TNF-a?)
What is PRP?
Plasma that has a platelet concentration 3-5x > peripheral blood
IRAP (conditioned autologous sera) has a high concentration of what cytokine?
IL-1ra –> competitively inhibits IL-1B
How do you calculate an IVF rate that includes correcting dehydration?
BW x % dehydration = deficit in LITERS
+ estimated ongoing losses (urine 1-2 mL/kg/hr; insensible losses 20 mL/kg/day)
+ maintenance rate (rec: 70x(BW^0.75))
LRS, P-Lyte, and Norm-R use which buffers?
LRS = lactate
P-Lyte and Norm-R = acetate and gluconate
What can happen if HTS is administered at >1 mL/kg/min?
Vagally mediated hypotension, bradycardia, bronchoconstriction
What is the blood volume of a dog? Cat?
Dog: 90 mL/kg
Cat: 50 mL/kg
What are the actions of PTH?
Increase Ca levels:
- Mobilizes Ca from bone
- Increases resorption of Ca in renal tubules
- Activates Vit D/calcitriol to increase GI absorption
What is the action of calcitonin
Antagonizes PTH by inhibiting Ca resorption/release from bone to decrease Ca levels in blood
Distributive shock is characterized by what single major systemic change? What is its effect on afterload?
Massive vasodilation
Decreases afterload
Equation for MAP
MAP = DAP + (SAP - DAP)/3
also
MAP = CO x SVR
O2 toxicity occurs at an FiO2 of __% for __ hrs
> 60% for 24 hrs
What is the primary physiologic activator of the clotting cascade?
Tissue factor (f3)
What is the most important activator of platelets?
Thrombin (f2)
What are the 3 anticoagulant pathways?
- Antithrombin: inactivates circulating coag proteins, activated by HMW heparin
- Activated Protein C: created when thrombin binds thrombomodulin –> inactivates f5 and f8 –> enhances fibrinolysis
- Tissue Factor Pathway Inhibitor: inactivates f10 and f7/TF complex, increased by heparin
PT tests which clotting pathways?
Extrinsic (TF/f7), common
aPTT tests which clotting pathways?
Intrinsic, common
ACT tests which clotting pathways?
extrinsic, intrinsic, common
Less sensitive than aPTT
D-dimers are sensitive indicators for what conditions?
Thrombotic conditions (DIC/TE)
What are the 3 types of vWD?
- Type 1 = presence of all multimers in REDUCED concentration (most common); If severe ( < 20% vWF) –> spontaneous bleeding
- Type 2 = disproportionate loss of HMW multimers
- Type 3 = almost complete absence < 1% vWF –> severe hemorrhage before 1yr
What is a positive ELISA result for vWD?
<50%
What is Virchow’s triad?
endothelial injury + vascular stasis + hypercoagulability = thrombotic tendency
What is the target aPTT during unfractionated heparin therapy?
1.5-2.5x normal
How does heparin work?
Inactivates f2 (thrombin) and f10
What is the pathogenesis of DIC? What is the mortality rate in dogs and cats?
Systemic activation of coagulation –> microvascular thrombosis –> compromises organ perfusion –> organ failure
50-75% mortality in dogs (sepsis, malignancy); 93% in cats (neoplasia, pancreatitis, sepsis, infection)
RER formula
30(BW) + 70
or
70(BW^0.75)
What albumin level is associated with increased postoperative complications?
<2 g/dL
Neutrophil killing depends on a PO2 of
PO2 > 40 mmHg
Angiogenesis is stimulated by what?
Macrophages and platelets
FGF, PDGF, TGF-B, VEGF, adhesins
What cells secrete the most VEGF?
Keratinocytes
Fibroblasts become myofibroblasts via
TGF-B1
Unwounded dermis primarily has what collagens in what %? Healing wounds have primarily what type of collagen?
Normal dermis: 80% type I, 20% type III
Healing dermis: primarily type III
How strong is a final scar?
Only 70-80% of unwounded tissue strength
Only 10% type III collagen in final scar
Order the breaking strength of the following tissues from most to least:
Skin, stomach, colon, bladder
Bladder > stomach > colon > skin
The strength of a GI closure significantly decreases during the first ____ due to _______ activity
During the first 48 hrs due to COLLAGENASE activity
Bladder gains 100% strength in ____ days
21 days
What are the differences in healing between dogs and cats?
Breaking strength of cutaneous wounds at 7 days better in dogs than cats
Granulation tissue earlier and more in dogs than cats
Contraction/epithelialization faster in dogs than cats
What is the critical colonization level for bacteria in tissue to result in infection?
10^5 bacteria/g
What is the strength of skin at 10-14 days post wounding? At 3 weeks?
5-10% at 10-14 days
25% at 3-4 weeks
What are the 3 classifications of SSI?
Superficial - skin/SQ only
Deep - fascia/muscle
Organ/space - anything deeper
How does surgical time affect the risk of a SSI?
Risk of SSI doubles for each hour of surgery
What is the reported SSI rate for clean surgery?
2.5 - 4.8%
What is a nosocomial infection?
Infection that occurs 48 hrs after hospital admission
Expected bacteria and prophylactic abx for each surgery type:
- Skin/recon + elective ortho
- Head/neck
- Open Fx
- Upper GI
- Hepatobiliary
- Lower GI
- Urogenital
- Skin/recon + elective ortho: Staph = cefazolin
- Head/neck: Staph/Strep/anaerobes = clinda, cefaz
- Open Fx: Staph/Strep/anaerobes = clinda, cefaz +/- aminoglycosides/fluoroquinolones
- Upper GI: Gram + cocci, Gram - bacilli, anaerobes = cefoxitin
- Hepatobiliary: Clostridium, Gram - bacilli, anaerobes = cefoxitin
- Lower GI: Enterococcus, Gram - bacilli, anaerobes = cefoxitin
- Urogenital = Strep/Staph/E. coli/anaerobes = cefazolin, ampicillin
What are the classifications for surgical procedures in terms of contamination level?
Clean = non-traumatic, uninfected + no break in asepsis + no inflammation elective, primarily closed 2-5% infection rate
Clean-Contaminated = controlled entry to hollow viscus, minor break in asepsis
Contaminated = open/fresh wound, incision into site with nonpurulent inflammation, major break in asepsis
Dirty = pus encountered, perforation of viscus, traumatic wound with devitalized tissues
What are the challenges of treating abscesses with antibiotics?
Pus = acidic pH, hypertonic, protein binding of selected drugs (aminoglycosides will bind to sediment)
Not good for penicillins (inactivated at pH < 6), aminoglycosides, and enro (work better in alkaline environments)
How do bacteria evade B-lactam antibiotics?
Beta-lactamase production
loss/change in porins
In addition to perioperative abx, what other things (3) will decrease the risk of SSI in surgery?
Normothermia, euglycemia, oxygenation
What materials cannot be sterilized with H2O2 gas/plasma/vapor?
Linen and paper –> absorb the H2O2
What materials cannot be sterilized with EtO?
nylon, polyvinyl chloride, polyvinylidene chloride, or foil
How does steam sterilization work? How should bowls be positioned?
kills via coagulation/denaturation of proteins with moist heat (including spores)
Water is a catalyst and heat is transferred by condensation
Bowls should be placed UPSIDE DOWN to prevent air trapping
Guidelines for gravity-displacement steam sterilization
121C for 30 min + 15-30 min dry time
132C for 15 min + 15-30 min dry time
What materials is dry heat sterilization good for? What is the protocol?
Sharps, powders, glass
160C for 120 min
How does ethylene oxide (EtO) sterilization work? What materials is it good for? What materials should you be mindful of?
Alkylation of proteins/nucleic acids
Good for heat and water sensitive things
Glass RESISTS EtO and rubber/plastic ABSORBS (requires aeration step)
How does ozone sterilization work? What materials cannot be sterilized this way?
O3 molecule readily oxidizes other molecules to destroy microorganisms (30-35C for 4 hrs)
NOT for wood/paper
How does plasma sterilization work? What materials cannot be sterilized this way?
electromagnetic energy to create plasma from vapor of H2O2, O2, or peracetic acid/H2O2 mix –> free radicals deactivate cell processes
NOT for linens, liquids, wood
What are the broad classes of sterilization indicators?
Physical
Chemical
Biologic
What are the classes of chemical indicators?
Class 1 = sterilization tape –> pack processed but limited info on parameters met
Class 2 = test for air removal (Bowie-Dick)
Class 3 = react to specific indicator [temp or time]
Class 4 = react to > 1 parameter
Class 5 = react to all parameters
Class 6 = monitor more specific guidelines (parameter required to combat prion infection)
What bacteria are used for biologic indicators? What was the failure rate of chemical indicators caught by these?
STEAM + OZONE + PLASMA = Geobacillus stearothermophilus
EtO = Bacillus atrophaeus
12% failure rate detected on chemical indicators
What is the storage time for (sterilization and wrapping):
Double-wrapped autoclaved/steamed
EtO Cloth
EtO Paper
EtO Plastic/tape
EtO plastic/heat sealed
Double-wrapped autoclaved/steamed: 96 wks
EtO Cloth: 15-30 d
EtO Paper: 30-60 d
EtO Plastic/tape: 90-100 d
EtO plastic/heat sealed: 1 yr
What is the ideal tooth angle for a ratchet on an instrument?
39 deg angle (better than 45 deg) –> enhanced security/engagement of interlocking teeth
Different tenotomy scissors
Stevens - ring-handled
Wescott - spring-loaded
What is the difference between straight tipped and curved tipped scissors?
Straight = better mechanical advantage
Curved = greater versatility/visibility
What are the crushing and non-crushing tissue forceps?
CRUSHING [tissues intended for excision]: R angle (vessel isolation) + Babcock + Allis + Oshner-Kocher
NON-CRUSHING: Doyen (thin/bowed jaws, fine long grooves) + DeBakey (unique long ribs) + Satinsky (partial vessel occlusion]
What is the ventilation requirement for the OR?
Minimum 15 air exchanges per hour
30-60% humidity
temperature 20-30C (68-73F)
What are the 2 types of corrosion and what are they caused by?
PITTING [pinprick holes from Cl- – saline, blood, water]
FRETTING [discoloration on friction surface]
What combination of antiseptics for patient prep can have residual antimicrobial activity on the skin?
Chlorhexidine gluconate (4%) + isopropyl alcohol (70%)
Which hand is more likely to have glove perforations in surgery?
What were the perforation rates for single versus double gloves?
Non-dominant hand more likely to get a hole
Single glove perforation = 12-30%
Double glove perforation = 10-45% for outer; 4-13% for inner
What antiseptic agent kills MRSA?
Chlorhexidine
When should you clip patients?
Within 4 hrs of surgery to reduce incidence of SSI
Do you use cut or coag when combining monopolar electrosurgery with instruments?
Cut
What are the 3 tissue effects of COAG with monopolar electrosurgery?
- Fulgaration = holding electrode away from tissue in coagulation mode –> random dispersion –> carbonization + superficial coagulum instead of vaporization
o Controls bleeding when no discrete bleeder »_space; smoke/char/necrosis - Desiccation = direct contact with tissue in coag mode –> dehydration + protein denaturation –> coagulum
o Eschar from overheating; more efficient heat than fulgaration = deeper thermal necrosis/spread - Coaptive = desiccation coagulation when lumen of vessel is occluded by metal instrument –> collagen weld
What vessel sizes can be sealed with:
Monopolar electrosurgery
Ultrasonic/Harmonic scalpel
Bipolar vessel sealing
And what is the thermal spread of each technique?
Monopolar electrosurgery: <2 mm
Ultrasonic/Harmonic scalpel: < 3 mm; thermal spread 0-1 mm
Bipolar vessel sealing: < 7 mm; thermal spread 1-3 mm (EnSeal <2 mm)
What does laser stand for?
Light Amplification by Stimulated Emission of Radiation
How does wavelength impact tissue penetration and which lasers are associated with which categories?
Longer wavelength = shallow tissue penetration/absorbed by H2O –> high surface temp + good cutting + min collateral (CO2, Ho:YAG)
Short wavelength = deeper tissue penetration/not absorbed by H2O –> coagulative necrosis at unpredictable zones (Nd:YAG, Diode)
Ultrashort wavelength = vascular tissue/absorbed by Hb (Argon)
Rank the following lasers in terms of depth of penetration (least to most): Nd:YAG, Argon, Diode, Excimer, CO2
Excimer < CO2 < Argon< Diode < Nd:YAG
[excited cats are doing nothing]
How does the Argon laser work and what is it typically used for?
Blue/green light absorbed by Hb
good for vascular lesions and endoscopy
Define:
knot pull out strength
Knot strength
Knot Pull Out Strength = load required to break suture deformed by knot
Knot Strength = force to cause knot to slip
How does pH affect glycolide and PDS/nylon suture degradation?
Glycolide degrades faster in ALKALINE pH
PDS/nylon degrade faster in ACIDIC pH
What is special about CHROMIC catgut suture
curing with chromium salts –> increased collagen cross-links –> decreased absorption and decreased inflammatory reaction
Vicryl: generic name, how long until 50% tensile strength, and time for absorption
Polyglactin 910
50% TS at 2-3 weeks
absorbed 56-70 days