Laws, Principles and Equations in anesthesia with applications (valley) – Flashcards
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Explains the release into the atmosphere of a large amount of gas from a compressed cylinder
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Boyle
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Squeezing the ambu bag raises pressure and decreases volume
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boyle
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Allows you to calculate how long a cylinder of gas will last at a given flow rate
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Boyle
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PV=k
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Boyle
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The inflatable cuff of an ETT or LMA expands during sterilization in an autoclave
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Charles
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Spirometry:conversion of gas volumes from body temp pressure, saturated) to ambient temp pressure saturated)
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Charles
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heat loss convection: as the air around the body is heated by convection, the volume of the mass of gas increases and therefore rises away from the patient
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Charles
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V/T=k
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charles
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When the temp of a closed cylinder increases, cylinder pressure increases
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Gay-Lussac's
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When the temp of a closed cylinder decreases, cylinder pressure decreases
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Gay-Lussac's
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As a cylinder containing liquid N2O empties, temp decreases (JT effect): as temp decreases, the pressure of N2O within the tank decreases
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Gay-Lussac's
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Wood's metal blows when temp increases substantially
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Gay-Lussc's
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explains the filling ration of N2O cylinders
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Gay-Lussac's
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P/T=k
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Gay-Lussac's
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Equal volumes of gases at the same temp and pressure contain the same number of molecules regardless of their chemical nature and physical properties
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Avogadro's number
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One mole is 6.02x10 (23) particles
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Avogadro's equation
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One mole of any gas at STP occupies 22.4liters
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Avogadro's equation
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Explains why tipping of a vaporizer is so hazardous: 1mL of typical volatile agent yields 200 mL vapor
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Avogadro's equation
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V/n=k
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Avogadro's equation
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A combination of Avogadro's, Boyles and Charles Las
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Ideal gas law
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As a cylinder of compressed gas empties, the pressure in the cylinder falls (because the number of moles is in the tank is decreasing)
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Ideal Gas Law
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Calculate amount of oxygen remaining in a cylinder from gauge pressure
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Ideal Gas Law
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PV=nRT
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Ideal gas Law
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permits calculation of the % concentration of a gas by dividing the partial pressure of the gas by the total pressure
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Daltons Law
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Permits calculation of the partial pressure of a gas by multiplying % concentration by total pressure
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Daltons law
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Ptotal=Pgas1+Pgas2.....
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Daltons law
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permits calculation of the amount of O2 dissolved in blood
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Henry's law
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permits calculation of the amount of CO2 dissolved in blood
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Henry's law
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The partial pressure of an anesthetic agent in the blood is proportional to the partial pressure of the volatile agent in the alveoli
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Henry's law
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hyperbaric oxygen therapy
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Henry's law
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at a constant temp, the mass of a gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid
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Henry's law
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concentration effect
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Fick's law
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second gas effect
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Fick's law
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diffusional hypoxia
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Fick's law
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expansion of gas spaces, or increase in pressure of closed gas spaces, when N20 is turned on
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Fick's law
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diffusion rate is directly proportional to
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pressure gradient, area, solubility
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diffusion rate is indirectly proportional to
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membrane thickness, square root of molecular weight
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the larger the gas molecule, the slower it diffuses across a membrane
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Graham's law
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part of the second gas effect; rapid uptake of a smaller molecule concentrates the larger molecules left behine
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Graham's law
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diffusion hypoxia
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Grahams law
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anything that causes an object to undergo a change in either movement, direction or shape
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force
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_______ is approximately the pressure of a piece of paper resting on a table
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1 Pascal (Pa)
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equivalents to 760 mmHg in kPa, bar, atm, psi
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1kPa=1bar=1 atm=14.7psi=760mmHg
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a larger/smaller syringe requires greater force to generate the same pressure
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larger
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an example of a spring+diaphragm valve
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APL valve
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in a linear system, the net force is the sum of the individual forces
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superimposition principle
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pulse pressure increases as the blood pressure wave travels to the periphery
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superimposition principle
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IV fluid administration, flow is increased by what factors and what law is it
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increasing diameter, decreasing length of needle, raising the IV bag to a greater height hagen-poiseuille
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the larger the ETT, the less resistance there is to flow
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hagen-poiseuille law
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taperd flowmeters with ball or bobbin
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hagen-poiseuille law
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the polycythemic patient has decreased blood flow through tissues
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hagen-poiseuille law
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the anemic patient has increased blood flow through tissues
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hagen-poiseuille law
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density is much more important than viscosity when it comes to turbulent flow
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Reynolds number
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heliox mixture
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Reynold number
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bruits: turbulent past plaques is audible
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Reynold number
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tapered flowmeters: at higher flow rates the bobbin moves up: density affects flow, hence calibration is gas or agent specific
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Reynold's number
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a blood vesse with an aneurysm has greater wall tension
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Law of Laplace
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with greater ventricular filling during diastole, there is increased tension in the wall at end-diastole
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law of Laplace
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In ARDS, smaller alveoli empty in larger alveoli
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Law of Laplace
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Explains why baby's first breath requires a very large negative intrathoracic pressure
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Law of Laplace
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Examples of what effect and equations: nebulizer (pneumatic and jet), venture mask, jet ventilator, injector, anterior leaflet in IHSS
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Venturi mask and Bernoullis equation
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as cylinder of compressed gas empties, the cylinder cools; condensation and ice crystals may be seen
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JT effect
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the cryoprobe operates on the basis of this
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JT effect
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conversion to fluid terms: Q=changeP/R
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Ohm's law
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calculation of systemic vascular resistance
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Ohm's law SVR=80 x (MAP-CVP)/CO
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calculation of resistance of flow through a tube
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Ohm's law
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pulse oximetry:ETCO2:infrared absorption spectroscopy
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Beer's Law (Lambert-Beer Law)
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medical ultrasound; always a trade off between resolution and imaging depth
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wave equation
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the smaller the wavelength (higher frequency), the greater the resolution, but lesser penetration
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wave equation
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gravitational attraction between two bodies, electrostatic forces, intensity of light, sound pressure
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inverse square law
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distance from the source determines the amount of exposure of the anesthetist to x-rays: intensity of scattered radiation is inversely proportional to the square of the distance form the source:
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inverse square law
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cardiac output
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CO=HRxSV
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increased CO predominantly due to an increase in
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HR
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stroke volume
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SV= EDV-ESV mL
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stroke volume is dependent on
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HR, contractility, preload and afterload
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the energy of contraction of a cardiac muscle fiber is proportional to the initial fiber length at _____ and whose law
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rest, Starling's law
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Ejection fraction
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EF= SV/EDV %
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pressure gradient that drives coronary blood flow
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coronary perfusion pressure
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coronary blood flow is more pronounced during
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diastole
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prolonged QT can predispose to
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ventricular arrhythmias (such as torsades de pointes)
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calculation of cardiac output from a-vO2 or a-vCO2 difference
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Fick principle
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uterine blood flow is/ is not autoregulated
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is not
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uterine blood flow is dependent upon maintain an adequate _____________ and minimizing ________-
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maintaining an adequate pressure gradient and minimizing uterine vascular resistance
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oxygen content (formula)
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CaO2=(Hbx1.34xSaO2)+(0.003xPaO2) mLO2/dL
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_____explains the benefit of using hyperbaric oxygen for carbon monoxide poisoning
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dissolved oxygen content
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surfactant______ the normal attracting forces between liquid molecules in the lung; these forces are responsible for ____________
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opposes, surface tension
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pulmonary fibrosis, atelectasis, pulmonary edema do what to pulmonary compliance
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decrease
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emphysema does what to pulmonary compliance
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increases
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a noncompliant left ventricle leads to
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diastolic cardiac failure
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yields the physiologic dead space as a fraction (%) of each tidal volume, what equation
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Bohr
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how does aging affect physiologic deadspace: doing what to the ratio; what equation
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aging increases, thus increases the ratio: Bohr equation
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alveolar CO2 is directly propotional to CO2 production and inversely proportional to alveolar ventilation
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alveolar ventilation equation
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equation used to calculate the ideal (theoretical)partial pressure of oxygen in the alveoli
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alveolar gas equation
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norm for alveolar gas equation
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90-104 mmHg, room air
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required to calculate the A-aO2 gradient; explains administration of supplemental O2 in the postoperative period (increased CO2)
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alveolar gas equation
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formula for alveolar gas equation
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PAO2= PiO2 - (PACO2/RQ)
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used to distinguish between restrictive and obstructive pulmonary diseases
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Forced expiratory ratio
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formula and norm for forced expiratory ratio
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FEV1/FVC 0.70-0.80 units
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what happens to the FEV1/FVC ratio in obstructive disease
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substantially decreases
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what happens to the FEV1/FVC ratio in restrictive disease
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the ratio is normal to high
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Components and norm of total lung capacity
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RV+ERV+TV+IRV 4.9-6.4L
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components and norm of functional residual capacity
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RV+ERV 2.2-3.0 L
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FRC is altered with
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lung and or chest wall disease
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preoxygenation (denitrogenation) is associated with what lung capacity
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functional residual capacity
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components of vital capacity
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ERV+TV+IRV 4.5-4.8L
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components of inspiratory capacity
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TV+ IRV 3.0-3.8 L
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quantifies the extent that venous blood bypasses oxygenation in the pulmonary capillaries of the lungs
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shunt equation
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these veins contribute to normal shunt
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thesbian and bronchial veins (5%)
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hypoxia caused by shunted blood can or cannot be remedied by breathing 100% oxygen
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cannot
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formula and norm for pulmonary vascular resistance
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PVR = (PAP-PAWP/CO)x80 -dyn-s/cm or - mmHg-min/L
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hypoxic pulmonary vasoconstriction impacts PVR in what way
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increases PVR
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elevated left atrial pressure impacts PVR in what way
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increases PVR
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A PE will typically impact PVR in what way
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increases PVR
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creatinine clearance gives an approximation of what value and function
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GFR and renal function
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cockroft-gault formula for creatinine clearance
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eCcr=-age)xmass (kg) x k/creatinine (serum) k= 1.23 male, 1.04 female
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osmolality and osmolarity formula
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(2xNa) + glucose + urea Na, glucose and urea must be in 270-310mOsm/L (orkg)
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anion gap formula and norm
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([Na]+[K])-([Cl]+[HCO3]): 10-20mEq/L or 8-16mmol/L
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formula and norm for cerebral perfusion pressure
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CPP=MAP-ICP 70-80
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cushing reflex is a sign of
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critically increased ICP
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autoregulation of CPP lies with MAP range
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50-150mmHg
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the driving force for both backward and forward (chemical) reactions is equal when the mixture is at equilibrium
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law of mass action
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when a system at equilibrium is subjected to change in concentration, temp, volume or pressure, then the equilibrium readjusts itself to counteract the effect of the applied change and a new equilibrium is established
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LeChatelier's Principle
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the solubility of a salt such as sodium chloride in water increases with increasing temp
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LeChateliers principle
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the solubility of a gas such as iso, O2 or CO2 increases with decreasing temp
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LeChatelier's principle
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when the concentration of a reactant is increased (or the concentration of product decreased), reaction is driven toward the production of more product, and the converse being true as well
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LeChatelier's principle
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The apparent (theoretical) volume unto which a drug disperses in order to produce the observed plasma concentration
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Volume of distribution
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The volume of distribution is a reflection of what 3 characteristics
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solubility, charge and molecular weight of a drug
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Water soluble drugs have a small/large volume of distribution and typically are polar/nonpolar
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small, polar
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Lipid soluble drugs have a small/large volume of distribution and typically are polar/nonpolar
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large, nonpolar
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the apparent (theoretical) volume of plasma completely cleared of a substance per unit of time
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clearance
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what two factors govern clearance
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metabolism and excretion
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formula for therapeutic index
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T1= TD50/ED50
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warfarin, digoxin and gentamicin all have what in common in relation to therapeutic index
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narrow, 2:1
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remifenitanil and diazepam have what in common in relation to therapeutic index
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wide, 33000:1 and 100:1 respectively
