Physics = Measurment Flashcards
(105 cards)
emergency oxygen flush?
100% oxygen is supplied from the common gas outlet, which has bypassed both flowmeters and vaporisers.
flow of oxygen is usually 45 l/min at a pressure of 400 kPa.
blood gas analysis
Heparin is an acid and will lower the pH of the sample
A warmed ABG from a hypothermic patient will show a higher PaO2, higher PaCO2 and a lower pH than that actually present in the patient’s blood in vivo.
standard bicarbonate is measured in a sample titrated to a PCO2 of 5.3, which eliminates the respiratory component, and is a reflection of the metabolic component.
Cardiac Output monitoring modalities
Oesophageal Doppler Transthoracic impedance PiCCO NICO Thermodilution Lithium dilution. (LIDCO)
Osmolarity solutes?
sodium salts (chloride and bicarbonate), glucose, and urea nitrogen
Caudal anaesthesia dose
Sacral procedure 0.5 ml/kg
Inguinal procedure 0.75 ml/kg
Lower thoracic 1 ml/kg
Mid-thoracic 1.5 ml/kg
Wright respirometer
One way system, exhaled tidal volume and minute volume.
+/- 5 to 10%.
150 revolutions when one litre of gas
minimum flow of 2 litres per minute is required
Humidification
Alveoli 43g/m3, @ 37*C
1 micron - ideal
US nebuloser - 2 MHZ
Damping - sine wave
Critical damping provides the quickest approach to zero amplitude (damping factor = 1).
With an optimally damped system there is a rapid initial decline in the oscillation to zero amplitude but there is then a small overshoot of about 6-7% of the original amplitude. An optimal damping factor of 0.64 is applied to blood pressure monitoring systems.
Axis deviation
If the mean vector is shifted superiorly and leftward (axis of −30° to −90°) left axis deviation (LAD) is present.
I, II, aVF used
Spectrophotometric absorption spectra
The isobestic point occurs at a wavelength around 800 nm. The maximum difference in the absorption of the two forms of haemoglobin occurs at a wavelength of about 650 nm.
Bernoulli’s principle
an increase in the speed of a fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid’s potential energy
Venturi effect
reduction in fluid pressure that results when a fluid flows through a constriction in a tube.
Coanda effect
a flow of gas or liquid attaches itself to a nearby surface and remains attached even when the surface curves away from the initial direction of flow.
Charles’s law:
At constant pressure the volume of a given mass of gas varies directly with absolute temperature
Boyle’s law
At constant temperature the volume of a given mass of gas varies inversely with pressure.
Gay-Lussac’s law
for a given amount of gas held at constant volume, the pressure is proportional to the absolute temperature:
Dalton’s law of partial pressure
The pressure of a mixture of gases is equal to the sum of the pressures of all of the constituent gases alone.
Henry’s law
At a constant temperature, the amount of a given gas dissolved in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
joule (J)
amount of energy expended if a force of one newton (N) is applied through a distance of one metre (N·m)
Kinetic energy (KE) =
½ MV2
potential energy (PE)
mass × height attained × acceleration due to gravity
Work done (WD)
V (potential difference) × I (current) × t (time)
Soda lime granules
94% calcium hydroxide, Ca(OH)2
5% sodium hydroxide, NaOH
1% potassium hydroxide, KOH
Baralyme
20% barium octahydrate and 80% calcium hydroxide
