Fellowship of the Royal College of Anaesthetists (FRCA) Physics, Clinical Measurement and Statistics Syllabus

Physics, Clinical Measurement and Statistics syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for Physics, Clinical Measurement and Statistics in Fellowship of the Royal College of Anaesthetists (FRCA), not a summary of it.

1. 1

   Applied Physics for Anaesthesia

   5 topics

   • Gas laws and the behaviour of gases
     • Boyle's, Charles' and Gay-Lussac's laws
     • Critical temperature and the diving cylinder
   • Flow, fluid dynamics and resistance
     • Laminar versus turbulent flow and Reynolds number
     • Hagen-Poiseuille equation and the Bernoulli principle
   • Pressure, force and SI units
   • Heat, temperature and humidity
     • Latent heat and mechanisms of heat loss
   • Solubility, diffusion and osmosis
2. 2

   Electricity, Lasers and Safety

   5 topics

   • Principles of electrical current and circuits
   • Electrical safety in theatre
     • Microshock, macroshock and leakage current
     • Equipment classification and isolation
   • Diathermy and surgical electrosurgery
   • Lasers and fibreoptics
     • Laser hazards and airway fire safety
   • Defibrillators and pacemakers
3. 3

   Clinical Measurement and Monitoring

   6 topics

   • Pressure measurement and transducers
     • Invasive arterial monitoring and damping
   • Gas analysis
     • Capnography waveform interpretation
     • Infrared, paramagnetic and mass spectrometry
   • Pulse oximetry and co-oximetry
     • Beer-Lambert law and sources of error
   • Temperature measurement
   • Neuromuscular and depth-of-anaesthesia monitoring
     • Train-of-four and processed EEG
   • Cardiac output monitoring technologies
4. 4

   Anaesthetic Equipment

   6 topics

   • Medical gas supply and the pipeline system
     • Cylinders, manifolds and oxygen concentrators
   • The anaesthetic machine and safety features
     • Flowmeters, vaporisers and oxygen failure alarms
   • Breathing systems
     • Mapleson classification and the circle system
     • Soda lime and carbon dioxide absorption
   • Airway equipment and ventilators
   • Scavenging and theatre pollution
   • Cleaning, sterilisation and single-use devices
5. 5

   Statistics and Data Interpretation

   5 topics

   • Types of data and descriptive statistics
     • Measures of central tendency and dispersion
     • Normal distribution and standard error
   • Hypothesis testing and probability
     • Null hypothesis, p-values and confidence intervals
     • Type I and Type II errors and statistical power
   • Common statistical tests
     • Parametric and non-parametric tests
     • Correlation and regression
   • Diagnostic test evaluation
     • Sensitivity, specificity and predictive values
   • Trial design, evidence and clinical research

Physics, Clinical Measurement and Statistics flashcards for Fellowship of the Royal College of Anaesthetists (FRCA)

19 of 79 cards from the Physics, Clinical Measurement and Statistics deck — real questions with worked answers.

1. State the ideal (universal) gas law and define each term.

   $$PV = nRT$$ where $P$ = pressure (Pa), $V$ = volume ($\text{m}^{3}$), $n$ = number of moles, $R$ = universal gas constant ($8.314\ \text{J K}^{-1}\text{mol}^{-1}$) and $T$ = absolute temperature (K).

2. State Boyle's law, Charles's law and Gay-Lussac's (Third) law, noting what is held constant in each.

   Boyle's law: at constant $T$, $P \propto \frac{1}{V}$. Charles's law: at constant $P$, $V \propto T$. Gay-Lussac's (Third gas) law: at constant $V$, $P \propto T$.

3. What is the Universal Gas Constant $R$ and its value in SI units?

   $R = 8.314\ \text{J K}^{-1}\text{mol}^{-1}$. It links the energy of one mole of gas to temperature in the ideal gas law, and equals $N_{A} k_{B}$ (Avogadro's number times Boltzmann's constant).

4. State Dalton's law of partial pressures and Henry's law.

   Dalton's law: in a mixture of non-reacting gases, the total pressure equals the sum of the partial pressures, $P_{total} = \sum P_{i}$. Henry's law: at constant temperature, the amount of a gas dissolved in a liquid is directly proportional to its partial pressure above the liquid.

5. Define the critical temperature of a gas and give the critical temperatures of nitrous oxide and oxygen.

   Critical temperature is the temperature above which a substance cannot be liquefied by pressure alone. $\ce{N2O}$: $36.5\,^{\circ}\text{C}$; oxygen: $-118\,^{\circ}\text{C}$. Because $\ce{N2O}$'s critical temperature is above room temperature it exists as liquid + vapour in a cylinder.

6. Distinguish laminar from turbulent flow and give the equation governing each.

   Laminar flow: smooth, streamlined; governed by the Hagen-Poiseuille equation $Q = \frac{\pi r^{4} \Delta P}{8 \eta l}$ (flow $\propto r^{4}$). Turbulent flow: chaotic; flow $\propto \sqrt{\Delta P}$ and $\propto r^{2}$, and depends on density rather than viscosity.

7. State the Hagen-Poiseuille equation and identify the most influential variable.

   $$Q = \frac{\pi r^{4} \Delta P}{8 \eta l}$$ where $Q$ = flow, $r$ = radius, $\Delta P$ = pressure gradient, $\eta$ = viscosity, $l$ = length. Radius is most influential because flow is proportional to $r^{4}$ (doubling radius increases flow 16-fold).

8. What is the Reynolds number, its formula, and the threshold value for turbulence?

   Reynolds number $Re = \frac{\rho v d}{\eta}$ ($\rho$ = density, $v$ = velocity, $d$ = diameter, $\eta$ = viscosity). $Re < 2000$ predicts laminar flow; $Re > 4000$ predicts turbulent flow; in between is transitional.

9. Explain the Bernoulli principle and the Venturi effect and give a clinical example.

   Bernoulli: as a fluid's velocity increases at a constriction, its pressure falls (conservation of energy). The Venturi effect uses this drop in pressure to entrain a second gas/fluid. Clinical example: fixed-performance Venturi oxygen masks and nebulisers.

10. What is the SI definition of the pascal, and how does it relate to mmHg and cmH2O?

    $1\ \text{Pa} = 1\ \text{N m}^{-2}$. Approximate conversions: $1\ \text{kPa} \approx 7.5\ \text{mmHg}$; $1\ \text{cmH}_2\text{O} \approx 0.74\ \text{mmHg}$; $1\ \text{atm} = 101.3\ \text{kPa} = 760\ \text{mmHg}$.

11. List the seven SI base units and their quantities.

    Metre (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), mole (amount of substance), candela (luminous intensity).

12. Define force, pressure and work in terms of SI base/derived units.

    Force: $F = ma$, unit newton ($\text{kg m s}^{-2}$). Pressure: $P = \frac{F}{A}$, unit pascal ($\text{N m}^{-2}$). Work/energy: $W = F \times d$, unit joule ($\text{N m}$).

13. Explain the principle behind the difference between gauge pressure and absolute pressure.

    Gauge pressure is measured relative to atmospheric pressure (atmospheric = 0). Absolute pressure is measured relative to a perfect vacuum: $P_{absolute} = P_{gauge} + P_{atmospheric}$. A cylinder gauge reading zero still contains gas at atmospheric pressure.

14. Define the three temperature scales' fixed points and the absolute zero value.

    Absolute zero $= 0\ \text{K} = -273.15\,^{\circ}\text{C}$. Water freezes at $0\,^{\circ}\text{C}$ (273.15 K) and boils at $100\,^{\circ}\text{C}$ (373.15 K) at 1 atm. Conversion: $K = \,^{\circ}\text{C} + 273.15$.

15. Define specific heat capacity and latent heat of vaporisation.

    Specific heat capacity: energy required to raise the temperature of 1 kg of a substance by 1 K ($\text{J kg}^{-1}\text{K}^{-1}$). Latent heat of vaporisation: energy required to convert 1 kg of liquid to vapour at constant temperature ($\text{J kg}^{-1}$).

16. Define absolute humidity, relative humidity, and state values at full saturation at 37 °C and 20 °C.

    Absolute humidity: mass of water vapour per volume of gas ($\text{g m}^{-3}$ or mg/L). Relative humidity: ratio of actual to maximum water vapour at that temperature, as a percentage. Fully saturated at $37\,^{\circ}\text{C} = 44\ \text{g m}^{-3}$; at $20\,^{\circ}\text{C} = 17\ \text{g m}^{-3}$.

17. Name two methods of measuring humidity (hygrometry).

    Hair hygrometer (hair length changes with humidity); wet-and-dry bulb hygrometer (evaporative cooling difference); Regnault's hygrometer (dew point); and the transducer/electrical (capacitance or resistance) hygrometer.

18. State Fick's law of diffusion and the factors it contains.

    $$\dot{V}_{gas} \propto \frac{A \cdot D \cdot \Delta P}{T}$$ where $A$ = area, $D$ = diffusion coefficient, $\Delta P$ = partial pressure gradient, $T$ = membrane thickness. The diffusion coefficient is proportional to solubility and inversely proportional to $\sqrt{\text{molecular weight}}$ (Graham's law).

19. Define osmosis, osmotic pressure and oncotic pressure.

    Osmosis: net movement of solvent across a semipermeable membrane from low to high solute concentration. Osmotic pressure: pressure needed to oppose this movement. Oncotic (colloid osmotic) pressure: the osmotic pressure exerted specifically by plasma proteins, ~25-28 mmHg.

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