Formulas Flashcards
maximum allowable blood loss
(EBV x (Hct starting- Hct target))/ Hct starting
Law of Laplace
pressure= (2 x tension) / radius
PVR
((mPAP-PAOP)/CO) x 80
Norm= 150-200
SVR
((MAP-CVP)/CO) x 80
Norm= 800-1500
metabolic equivalent
metabolic rate of specific physical activity/metabolic rate at rest
trans pulmonary pressure
alveolar pressure-intraplural pressure
Alveolar ventilation
(TV- dead space) x RR or CO2 production/PaCO2
minute ventilation (VE)
TV x RR or Vt x RR
dead space to tidal volume ration (Vd/Vt)
0.33 in SV patient, 0.5 in mechanical ventilation
PaCO2-PeCO2)/PaCO2 (PeCo2=partial pressure of CO2 in exhaled gas, not the same as ETCO2
Law of Laplace cylinder
tension=pressure x radius
Law of Laplace sphere
tension = (pressure x radius)/2
Alveolar oxygen (PAO2)
FiO2 x (Pb - PH2O) - (PaCO2 / RQ) PH2O= humidity of inhaled gas, assumed to be 47 mmHg RQ= respiratory quotient, assumed to be 0.8 Normal 105.98 mmHg
Can estimate FiO2 x 6
Respiratory quotient
Co2 production/O2 consuption= 200 mL/min / 250 mL/min =0.8
>1= lipogenesis (overfeeding)
<1= lipolysis (Starvation)
Estimation of shunt %
Shunt increases 1% for every 20 mmHg A-a gradient
TV
FRC
VC
TV= 6-8 mL/kg
FRC= 35 mL/kg
VC= 65-75 mL/kg
calculated with ideal body weight
CaO2
O2 carrying capacity
(1.34 x SaO2 x Hgb) + (PaO2 x 0.003)
Normally 20 ml O2/dL
DO2
O2 delivery
CaO2 x CO x 10
Normally about 1000 mL O2/min
Normal H and H values
women 13 and 39
men 15 and 45
VO2
O2 consumption CO x (CaO2-CvO2) x 10
3.5 mL/kg/min
250 mL/min in 70 kg patient
Normal P50 O2
Where hgb 50% saturated by O2
26.5 mmHg
Lower= L
Higher= R
Bicarb reaction in blood
70%
H2O + CO2 H2CO3(carbonic acid) H+ + HCO3-
Need carbonic anhydrase for first reaction
H+ buffered by Hmg
HCO3 transported in plasma, Cl- goes into cell
Co2 bound to hemoglobin
23%
R-NH2 + CO2 RNH-CO2- + H+
Co2 dissolved in plasma
7%
solubility coefficient 0.067 mL/dL/mmHg
Vd/Vt
2ml/kg / 6mL/kg (normally 0.33)
increases to 0.5 in mechanical ventilation
FiO2
((Air flow rate x 21) + (O2 flow rate x 100)) / Total flow rate
Tidal volume with fresh gas coupling
Vt on ventilator - FGF during inspiration - vol lost to compliance
- Convert fresh gas flow from L/min to mL/min
- Multiple by FGF by the percentage of time in inspiration (1:2 IE= 33.33%)
- Divide 2 by RR.
- Add set Vt to 3.
Most new ventilators decouple so this does not apply
Reynold’s number
(Density x diameter x velocity)/viscosity
Re<2000= laminar flow (dependent on gas viscosity)
Re > 4000= turbulent flow (depending on gas density)
2000-4000= transitional flow
Volume lost to circuit
Circuit compliance x peak pressure
Some of Vt used to expand circuit
mL of liquid anesthetic agent used per hour
Vol% x FGF in L/min x 3
calculating vaporizer output at elevation
Required dial setting= (normal dial setting x 760)/ambient pressure (mmHg)
Higher altitude= higher setting
Lower altitude= lower setting
reaction of CO2 with sodalime
CO2 + H2O = H2CO3 (carbonic acid)
H2CO3 + 2 NaOH = Na2CO3 + 2 H2O + heat
Na2CO3 + Ca(OH)2 = CaCO3 (calcium carbonate) + 2 NaOH (sodium hydroxide)
Absorbent capacities
Soda lime 26L of CO2 per 100 g
Calcium hydroxide lime 10.6 L per 100g
reaction of CO2 with calcium hydroxide lime
CO2 + H2O= H2CO3
H2CO3 + Ca(OH)2 = CaCO3 + 2H2O + energy(heat)
No CO and very title compound A
Lower fire risk
Less absorbent capacity
Hydration of sodalime
13-20% by weight
Mapleson for SV and controlled ventilation
SV- A > DFE > CB
CV- DFE> BC> A
Plateau pressure
Pressure in smal airways and alveoli after tital volume is delivered
During inspiratory pause
Barotrauma risk increased with pressure > 35 cm/H2O
Static compliance= tidal volume/ (plateau pressure- PEEP)
Peak inspiratory pressure
Maximum pressure during inspiration
Dynamic compliance= tidal volume/ (PIP-PEEP)
Dysfunctional hemoglobin
Carboxyhemoglobin- absorbs 660 at same rate as oxyhemoglobin, Overestimates SpO2
Methemoglobin- absorbs 660 and 990 equally, Underestimates if > 85%
Overestimates if < 85%
SPO2
Oxygenated hgb/ (oxygenated hgb + deoxygenated hgb) X 100%
BP cuff sizing
length- long enough to wrap around 80% of arm
width- 40% circumference of patients arm
Arm position and NIBP reading
10 cm= 7.4 mmHg change
1 inch= 2 mmHg
Mixed venous O2 saturation
SvO2= SaO2- (VO2/(Q x 1.34 x Hgb x 10)) Normal= 65-75%
VO2= oxygen consumption SaO2= loading of hemoglobin in arterial blood
Need a PA cath to get blood from SVC, IVC, and coronary sinus together
Bipolar leads
I- lateral, CxA
II- inferior, RCA
III- inferior, RCA
Limb leads
AVR
AVL
Lateral
CxA
aVF
Inferior
RCA
Precordial
V1- septum, LAD V2- septum, LAD V3- anterior, LAD V4- anterior, LAD V5- lateral, CxA V6- lateral, CxA
Axis deviation
Use lead 1 and aVF
+ and += normal (between -30 and +90)
- and -= extreme R
Leads are Reaching towards each other(I down and aVF up)= R (greater than 90)
Leads are Leaving each other (I up and aVF down)= L (less than -30)
Class 1 antiarrhythmic
Na+ channel blockers
1A- quinidine, procainamide, disopyramide
Phase 0 dep, prolonged phase 3 repol
1B- lidocaine, phenytoin
Phase 0 dep, shortened phase 3 repol
1C- flea indie, propafenone
Strong phase 0 dep
Class 2 anti arrhythmic
Beta blockers
Slows phase 4 depol in SA node
Class 3 antiarrhythmic
K+ channel blockers
Amiodarone, bretylium
Prolongs phase 3 repolarization
Increased effective refractory period
Class 4 antiarrhythmic
Ca Channel blockers
Verapamil, dilt
Decreased conduction velocity through AV node
Torsades pneumonic
POINTES Phenothiazines Other meds- methadone, droperidol, haldol, zofran, halogenated agents, amiodarone, quinidine Intracranial bleed No known cause Type I antiarhythmics Electrolyte disturbances- low K, low Ca, low Mg Syndromes- Romano ward, Timothy
EEG waveforms
Beta- high frequency, low voltage, awake or light anesthesia
Alpha- medium frequency, awake but restful with eyes closed
Theta- general anesthesia and children sleeping
Delta- low frequency, GA, deep sleep, and brain injury
Definition of pulmonary hypertension
PAP > 25 mmHg
PVR
((mean PAP - PAOP) X 80) / CO
Norm= 150-250 dynes/sec/cm to the -5th power
Drugs you can give in ETT
NAVEL
Narcan, atropine, vasopressin, epi, lidocaine
Objective measures of respiratory distress
Vital capacity (mL/kg)- <15
Inspiratory force (cm/H2O)- <25
Oxygenation at 21%- PaO2 <55, A-a gradient >55
Oxygenation at 100%- PaO2 < 200, A-a gradient >450
PaCO2 >60
RR >40 or <6
Indicators of postoperative pulmonary complications in patients undergoing pulmonary surgery
Airflow: FEV1<40% of predicted
Gas exchange: DLCO < 40% of predicted
Cardiopulmonary reserve: VO2 max < 15 mL/kg/min (normal male=35-40, normal female=27-31) (if can’t climb 2 flights of stairs, this patient is at risk)
Double lumen tube placement
Male: size 39-41 fr, depth 29cm
Female: size 37-29 fr, depth 27cm
Children 8-9: 26 size
Childre >10 : 28 or 32 size
Lateral decubitus and V/Q
Nondependent- better ventilated
Dependent- better perfused
Mallampati pneumonic
PUSH
Pillars, uvula, soft palate, hard palate
Atlantoocciptal joint mobility
Normal flexion and extension: 90-165 degrees
Normal extension: 35 degrees (difficult DL if less than 23 degrees)
Risk factors for difficult mask
BONES Beard Obesity- BMI>26 No teeth Elderly- age>55 Snoring
NPO guidelines
2 hours- clear liquids
4hours- breast milk
6 hours- non human milk, solids, infant formula
8 hours- fatty food
Mendelson syndrome
risk factors- Gastric pH <2.5, gastric volume>25mL (0.4 mL/kg)
Risk reduced by clear liquids 2 hours before
Pressure for cricoid
Before LOC- 20 newtons or 2kg
After LOC- 40 newtons or 4kg
large tongue pneumonic
Big Tongue
Beckwith syndrome
Trisomy 21
small chin pneumonic
Please Get That Chin Pierre robin Goldenhar Treacher collins Cru di chat
cervical spine anomaly pneumonic
Kids TRY Gold
Klippel-feil
Trisomy 21
Goldenhar
ETT size in peds
ETT without cuff- (Age/4) +4
Depth- ID x 3
Total body water
42L in 70 kg adult male (60% of total body weight) ICV 40% of total body weight or 28 L ECV 20% of total body weight or 14 L 16% interstitial fluid 11L 4%plasma fluid (3L)
Plasma osmolarity
(Na x 2) + (glucose/18) + (BUN/2.8)
normal= 280-290 mOsm/L
Solutions
Hypotonic 255 mOsm/L
Ex: NaCl 0.45%, D5W
Isotonic 285 mOsm/L
Ex: NaCl 0.9%, 5% albumin, LR, plasmalyte A, Voluten 6%, Vespan 6%
Hypertonic 315 mOsm/L
Ex: NaCl 3%, D5 NaCl 0.45% and 0.9%, D5 LR, Dextran 10%
Coagulopathy with synthetic colloids
Dextran > hetastartch> hextend
don’t exceed 20mL/kg
not a problem with Voluten
PaCo2 impact on pH
Acute respiratory acidosis
PaCO2 increases 10mmHg= pH decrease 0.08
Chronic respiratory alkalosis
PaCO2 increases 10mmHg= pH decrease 0.03
anion ion gap
Major cations - major anions
Na - (Cl + HCO3)= 8-12 mEq/L
accumulation of acid= gap acidosis (Anion gap >14)
loss of bicarb or ECF dilution= non gap acidosis (anion gap <14)
anion gap acidosis pneumonic
MUDPILES Methanol Uremia Diabetic ketoacids Pareldehyde Isoniazid Lactate Ethanol, ethylene glycol Salicylates
non anion gap acidosis pneumonic
HARDUP Hypoaldosteronism Acetazolamide Renal tubular acidosis Diarrhea Ureterosigmoid fistula Pancreatic fistula
Net filtration pressure
(Capillary hydrostatic pressure- interstitial hydrostatic pressure) - (plasma oncotic pressure- interstitial oncotic pressure)
Na concentration in fluids
any solution with NaCl (including 5% albumin)= 154mEq/L
any solution with LR= 130 mEq/L
plasmalyte= 140 mEq/L
Clotting factors pneumonic
Foolish people try climbing long slopes after Christmas, some people have fallen 1- fibrinogen 2- prothrombin 3- tissue factor 4-calcium 5- labile factor 7- stable factor 8- anti hemophilic factor 9- Christmas factor 10- Stuart prower factor 11- plasma antithrombin antecedent 12- Hageman factor 13- fibrin stabilizing factor
Extrinsic pathway
For 37 cents, you can purchase the extrinsic pathway
very fast
Intrinsic pathway
If you can’t buy the intrinsic pathway for $12, you can buy it for $11.98
slower, can take up to 6 min
final common pathway
The final common pathway can be purchased at the 5 and dime(X) for 1 or 2 dollars on the 13th of the month
volume of distribution
amount of drug/desired plasma concentration
loading dose
vd x desired plasma concentration/bioavailability
bioavailabiity=1 with IV drug
extraction ratio
(arterial concentration- venous concentration)/arterial concentration
flow limited >0.7- increased blood flow increases clearance
capacity limited <0.3- changes in enzymes impact clearance, not impacted by blood flow
low hepatic ratio drugs
roc, diazepam, lorazepam, methadone, thiopental, theophylline, phenytoin
aPTT
norm 25-32 sec
measures intrinsic and common
Factors reduced by 30% for changes in #
response to unfractionized heparin, NOT LMWH
PT/INR
norm 12-14 sec
measures extrinsic and common
Factors reduced by 30% for changes in #
response to warfarin
norm 1
standardized form of PT
Bleeding time
norm 2-10min
prolonged by aspirin and NSAIDs
ACT
norm 90-120 sec
heparin dosing
>400 for bypass
Cranial nerve pneumonic
Oh Oh Oh To Touch And Feel Virgin Girls Vagina and Hymen
Some Say Marry Money But Brother Says Bad Business to Marry Money
CSF flow pneumonic
Love My 3 Silly 4 Lorn Magpies
Laternal Monroe 3rd ventricle Sylvius 4th ventricle Luschka Magendie
Cerebral blood flow
cerebral perfusion pressure/ cerebral vascular resistance
CMRO2
3-3.8 mL/O2/100g brain tissue/min
Decreases by 7% for every 1 degree celsius
CPP
MAP - ICP or CVP (whichever is higher)
autoregulation 50-150
PaCO2 in brain
At PaCO2 of 40mmHg, there is 50mL/100g brain tissue/min
every 1mmHg increase in PaCo2=1-2mL increase in good flow
Max vasodilation @ 80-100mmHg
Max vasoconstriction @ 25mmHg
metabolic acidosis does not impact CBF
PaO2 in brain
below 50-60mmHg=vasodilation and increases CBF
hyperventilation and brain
PaCo2 30-35 mmHg
less than 30 increases risk due to vasocontriction and left shift of curve
effect lasts 6-20 hours
therapy for vasospasm
hypervolemia hypertension hemodilution- hit 27-32% nimodine is only Ca channel blocker used daily transcranial doppler
Cerebral salt wasting syndrome
Occurs with SAH
from brain releasing natriuretic peptide
treated with isotonic crystalloids
Not SIADH
Artery of Adamkiewicz
perfuses anterior cord in thoracolumbar region
most commonly T11-12 (75% of population T8-12, L1-2 in other 10%)
Anterior spinal artery syndrome
also known as Beck syndrome
when aortic clamp is place above artery of adamkiewicz
symptoms- flaccid paralysis of lower extremities, bowel and bladder dysfunction, loss of temp and pain, preserved touch and proprioception
tracts perfused by anterior spinal arteries
corticospinal tract- causes flaccid paralysis
autonomic motor fibers- causes bladder and bowel dysfunction
spinothalmic tract- causes temp and pain loss
tracts perfused by posterior spinal arteries
dorsal column- touch and proprioception
dorsal column medial leminiscal
fine touch, proprioception, vibration, and pressure
large, myelinated fibers
rapidly conduction (faster than anterolateral)
1st order- periphery to medulla
2nd order- medulla to thalamus (crosses)
3rd order- thalamus to parietal lobe
Spinothalmic tract
anterolateral system
pain, temp, crude touch, tickle, sexual sensation
smaller, myelinated, slower conduction
1st order- periphery to spinal cord (ascends or descends 1-3 levels in Lissauer tract before synapse)
2nd order- dorsal horn of cord to RAS or thalamus (in anterior or lateral spinothalmic tract)
3rd order- to thalamus
Corticospinal tract
Pyramidal system
Most important motor pathway
Lateral- cross in medulla, to limb muscles
Ventral- remain on ipsilateral side and descend into cord (typically in cervical or thoracic), axial muscles
upper motor neuron injury- hyperreflexia and spastic paralysis, Tested by Babinski
Lower motor neuron- ventral horn to NMJ, injury: paralysis on same side, impaired reflexes and flaccid paralysis , no babinski
Dantrolene dosing
2.5 mg/kg IV, repeat 5-10min
1mg/kg for 6 hr infusion, or 0.1-0.3mcg/kg/hr for 48-72 hrs
if more than 20mg/kg reconsider diagnosis
20mg dantrolend and 3g mannitol per bottle
constituted with 60 mL preservative free water
Ryanodex
2.5mg/kg IV
container 250 mg dantrole with 5mL sterile water diluent
diseases linked to MH
king-denbourough syndrome
central core disease
multiminicore syndrome
adrenal medulla secretion
80% epi, 20% norepi
NE to epi conversion occurs in the adrenal mudella
metabolites of NE
preliminary- metanephrine, normetanephrine
final- vanillylmandelic acid (3 methoxy-4-hydroxymandellic acid)
elevated VMA in urine = pheochromocytoma
Autonomic efferent pathway
Preganglionic efferent- myelinated B fiber, releases acetylcholine onto nicotinic type N receptor in autonomic ganglion
Post ganglionic efferent- nonmyelinated C fiber, PNS releases AcH onto effector organ, SNS releases NE onto effector organ (a few exceptions)
SNS exceptions
postganglionic releases Ach onto N receptors of sweat glands, pilorector muscles, and some vessels
no postganglionic at adrenal medulla, chromafin cells release NE and epi into circulation
ANS post to preganglionic ratio
SNS- 30:1, causes postsynaptic amplification
PNS- 1-3:1, precise control
White rami
Preganglionic sympathetic fibers enter cord through ventral horn
get into sympathetic chain on white rami (myelinated)
Grey rami
after exiting chain, reenter spinal nerve on grey rami to real with it to target organs
sweat glands, pilorector muscles, and vasculature
Horner syndrome
blockade of stellate ganglion, happens on ipsilateral side Very Homely PAM Vasodilaiton Horner Ptosis Anhydrosis Miosis (also enopthalmus)
resting rate of NE and epi release from adrenal medulla
NE- 0.05 mcg/kg/min
epi- 0.2 mcg/kg/min
Baroreceptor sensors
Carotid sinus- in internal carotid right after bifurcation, carotid sinus nerves (nerves of Hering) converge with glossopharyngeal
Transverse aortic arch- sends info via vagus nerve
Beta 1 selective antagonists
MABE AB Metoprolol Atenolol-kideny is primary route of elimination Betaxolol Esmolol- RBC esterases Acebutolol Bisoprolol
Nonselective beta antagonists
Labetolol- mixed beta and alpha, 7:1, intrinsic sympathomimetic activity
Timolol
Propranolol
Pindolol- intrinsic sympathomimetic activity
Nadolol
Carvediolol- mixed beta and alpha, 10:1
Alpha blockers
Phentoalamine- short acting, nonselective, competitive alpha blocker
Phenoxybezamine- long acting, non selective, noncompetitive alpha blocker
Prazosin- selective alpha 1
Origin of efferent SNS pathways
T1-L3
axons exit via ventral roots
synapse in 22 sympathetic ganglia
Origin efferent PNS pathways
CN 3,7,9,10
Sacral 2-4
synapse on effector organ
Catecholamines by size
smallest to largest
dopamine, NE, epi, isoproterenol, dobutamine
Renal medulla structures
loops of henle, collecting ducts
Kidneys portion of CO
20-25%, 1000-1250 mL/min
Livers portion of CO
30%, 1500mL/min
Blood and O2 puppy to liver
Hepatic artery- 25% blood flow, 50% O2
Portal vein- 75% blood flow, 50% O2
Portal vein pressure values
7-10, >20-30=portal hypertension
hepatic arterial buffer response
hepatic artery perfusion pressure= MAP- hepatic vein pressure
mediated by adenosine
coag factors not produced by hepatocytes
Von Willebrand factor- vascular endothelial cells
Factor 4
Factor 3- vascular endothelial cells
Factor 8- liver sinusoidal cells and endothelial cells
end of subarachnoid space in adults and children
adults- S2
children- S3
Spine landmarks
L1- conus medullaris
L4-5 interspace= Tuffier’s line (correlates with iliac crests)
S2- dural sac ends (correlates with superior iliac spines) (S3 in neonates)
S5- sacral hiatus and sacrococcygeal ligament
Spinal differential blockade
- autonomic fibers
- sensory fibers
- motor fibers
autonomic block 2-6 dermatomes higher than sensory
sensory block 2 dermatomes higher than motor
Epidural differential blockade
no autonomic differential
sensory block 2 dermatomes higher than motor
order of block onset by nerve fibers
- B- preganglionic ANS
- C- postganglionic sympathetic, slow pain, temp, touch
- A gamma- skeletal muscle tone, A delta- fast pain, temp, touch
- A alpha- skeletal muscle motor and proprioception, A beta- touch, pressure
pre ganglionic sympathetic, temp, pin prick (fast pain), touch, motor
valve lesions to consider with neuraxial
severe aortic stenosis
severe mitral stenosis
hypertrophic cardiomyopathy
MS and neuraxial
epidural safe
spinal may exacerbate symptoms
CSF specific gravity
1.002-1.009
Baricity of LA
dextrose= hyperbaric
NS= isobaric
water= hypobaric
EXCEPTION- 10% procaine in water is hyperbaric
depth of epidural catheter
3-5cm into epidural space
caudal anesthesia kids dosing
sacral- 0.5 mL/kg
sacral to T10- 1mL/kg
sacral to mid thoracic- 1.25mL/kg
can add clonidine 1mcg/kg
no dose greater than 2.5-3mg/kg
caudal anesthesia adult dosing
sacral: 10-15 mL
sacral to T10: 20-30mL
sacral to mid thoracic- NA
side effects of neuraxial opiods
pruritis- most common
respiratory depression
urinary retention- most common in young males
N/V
conus medullaris
adult: L1-2
neonate: L3
end of SC
cauda equina syndrome
exposure of high concentration to LA’s
5% lido and micro spinal catheters
bowel/bladder dysfunction, paralysis, sensory deficits
supportive treatment
transient neurologic syndrome
unlikely it is caused by toxicity
lidocaine, lithotomy, knee scope, ambulatory surgery
severe back pain radiating to butt and legs
within 6-36 hours and resolves in 1-7 days
NSAIDs, opioids, and trigger point injections
most resistant nerve roots to LA
L5 and S1
Largest spinal nerves
